Q: Prognosis of Patellofemoral Pain: A Systematic Review With Evidence-and Gap-Map

Objective To systematically appraise current prognostic factor literature for patellofemoral pain (PFP). Design Systematic review with evidence- and gap-map. Literature Search PubMed, CINAHL complete, PEDro, Scopus, SPORTDiscus, Embase, Cochrane Database of Systematic Reviews, and Web of Science (from inception to April 2024). Study selection criteria Included participants were those with symptoms consistent with PFP and an average age ≤45 years. Eligible studies were longitudinal cohort studies and randomized controlled trials with a true “wait-and-see” group that measured at least 1 outcome variable at 2 time points and at least 1 potential prognostic factor at baseline. Data synthesis Prognostic factors were iteratively grouped relative to 7 categories and mapped by population and follow-up. Results Ten longitudinal cohort studies and 12 randomized controlled trials were included. The most frequently evaluated prognostic factors were sociodemographic (n = 21), anthropometric (n = 21), and symptoms and function (n = 19). Fewer studies evaluated biomechanics (n = 12), behavioral (n = 11), psychological (n = 6), and neurobiological (n = 4) factors. Most studies examined the general population (n = 13), with fewer studies in specific populations (adolescents, n = 4; military, n = 2; runners, n = 2; university athletes, n = 1). Most studies evaluated short-term (≤3 months; n = 9) or long-term (>1 year; n = 11) follow-up, with only 2 studies evaluating medium-term follow-up (3 months to 1 year). Conclusion Sociodemographic, anthropometric, and symptoms and function factors were the most studied prognostic factors for PFP. Neurobiological, psychological, biomechanical, and behavioral factors were understudied. Additional studies are needed to identify prognostic factors in specific populations with high incidence of PFP. A comprehensive understanding of prognostic factors may inform development and implementation of evidence-based interventions.

Question 1

Patellofemoral Pain After Knee Trauma: Exploring Clinical, Biomechanical, and Muscle Strength Variables

Accepted Answer

It remains unclear whether people with traumatic-onset patellofemoral pain (PFP_T) present with the same physical and non-physical changes as people with gradual-onset patellofemoral pain (PFP_A). In this cross-sectional study, we aimed to compare clinical, biomechanical and muscle strength outcomes between people with PFP_T, people with PFP_A, pain-free controls with a history of knee trauma (CTRL_T), and pain-free controls without a history of knee trauma (CTRL_A). Clinical variables included pain-related characteristics, time since knee trauma, kinesiophobia, and functional capacity (e.g., self-reported, objective). We captured kinematics and kinetics during a single-leg landing task, and maximal isometric torque of the knee extensors and flexors, and the hip abductors using an isokinetic dynamometer. We performed between-group comparisons using generalized linear models and independent t-tests. The PFP_T group reported higher pain, greater kinesiophobia, and lower self-reported function compared with the PFP_A group. The PFP_T group also demonstrated greater peak trunk flexion, greater peak hip flexion, and a lower knee contribution to the total support moment (TSM) compared with the PFP_A group. Both the PFP_T and PFP_A groups demonstrated reduced isometric peak torque of the knee extensors compared with the CTRL_T group. The CTRL_T group demonstrated higher peak hip flexion, lower knee contribution to TSM, and greater patellofemoral joint stress compared with CTRL_A. People with PFP_T demonstrated a worse clinical profile and a more hip-dominant landing strategy compared with those with PFP_A. Most impairments (e.g., landing biomechanics and muscle strength) were evident only in comparison with CTRL_T, who also differed clinically and mechanically from CTRL_A.

Question 2

Intracortical inhibition, corticospinal excitability and voluntary activation in people with and without patellofemoral pain

Accepted Answer

The aims of this study were to investigate the intra-rater reliability of peripheral nerve stimulation (PNS) and transcranial magnetic stimulation (TMS) in people with andwithout patellofemoral pain (PFP) and to compare nervous system function between these groups, using a case–control design. We sought people with and without PFPto participate in PNS and TMS testing to calculate maximal compound motor action potential, maximal force, voluntary activation (VA), active motor threshold (AMT), corticospinal excitability (CSE), silent period, and short-interval intracortical inhibition.People with PFP also rated their current pain and function. Single-measure intraclass correlation coefficients with 95% confidence intervals were used to determine intra-rater reliability, with standard error of measurement and minimum detectable change calculated. Between-group differences in PNS and TMS variables were determined using Student’s two-tailed, independent samples t-tests or Mann–Whitney U-tests. Twenty-seven people without and 23 people with PFP completed PNS and TMS testing. For intra-rater reliability, 18 people without and 17 people with PFP returned fora second testing session, and intraclass correlation coefficient values ranged from good to excellent (0.62–0.96). People with PFP demonstrated significantly lower VA(P < 0.0001), higher AMT (P = 0.014), and lower CSE (P = 0.018). In conclusion, both PNS and TMS demonstrate acceptable intra-rater reliability in people with and without PFP. Elevated AMT and reduced CSE indicate that people with PFP might have a hypoexcitable motor cortex–corticospinal pathway, and lower VA indicates reduced recruitment of high-threshold motor units. These findings indicate that a neurophysiological mechanism might underpin the poor prognosis of PFP.

Question 3

Prognosis of Patellofemoral Pain: A Systematic Review With Evidence-and Gap-Map

Accepted Answer

Objective To systematically appraise current prognostic factor literature for patellofemoral pain (PFP).
Design Systematic review with evidence- and gap-map.
Literature Search PubMed, CINAHL complete, PEDro, Scopus, SPORTDiscus, Embase, Cochrane Database of Systematic Reviews, and Web of Science (from inception to April 2024).
Study selection criteria Included participants were those with symptoms consistent with PFP and an average age ≤45 years. Eligible studies were longitudinal cohort studies and randomized controlled trials with a true “wait-and-see” group that measured at least 1 outcome variable at 2 time points and at least 1 potential prognostic factor at baseline.
Data synthesis Prognostic factors were iteratively grouped relative to 7 categories and mapped by population and follow-up.
Results Ten longitudinal cohort studies and 12 randomized controlled trials were included. The most frequently evaluated prognostic factors were sociodemographic (n = 21), anthropometric (n = 21), and symptoms and function (n = 19). Fewer studies evaluated biomechanics (n = 12), behavioral (n = 11), psychological (n = 6), and neurobiological (n = 4) factors. Most studies examined the general population (n = 13), with fewer studies in specific populations (adolescents, n = 4; military, n = 2; runners, n = 2; university athletes, n = 1). Most studies evaluated short-term (≤3 months; n = 9) or long-term (>1 year; n = 11) follow-up, with only 2 studies evaluating medium-term follow-up (3 months to 1 year).
Conclusion Sociodemographic, anthropometric, and symptoms and function factors were the most studied prognostic factors for PFP. Neurobiological, psychological, biomechanical, and behavioral factors were understudied. Additional studies are needed to identify prognostic factors in specific populations with high incidence of PFP. A comprehensive understanding of prognostic factors may inform development and implementation of evidence-based interventions.

Question 4

What Prognostic Indicators and Treatment Mechanisms Exist for Efficacious Treatments in People With Patellofemoral Pain? A Secondary Meta-regression With an Updated Search

Accepted Answer

Objective To investigate the prognostic and mechanistic variables associated with efficacious treatments in people with patellofemoral pain (PFP).
Design Updated intervention systematic review with de novo meta-regression.
Literature Search We searched MEDLINE, Web of Science, and Scopus from inception until October 2023 for randomized controlled trials (RCTs) involving people with PFP.
Study selection criteria High-quality RCTs (scoring ≥7 on the PEDro scale) involving participants with PFP and at least 1 treatment arm involving an efficacious intervention.
Data synthesis We extracted homogenous pain and function data to calculate effect sizes to regress with baseline prognostic (eg, symptom duration) and mechanistic (eg, strength change) data.
Results Thirty-four high-quality RCTs involving 1526 people with PFP were included. For knee-targeted exercise, we identified symptom duration (R2 = 0.68), older age (R2 = 0.31), and low baseline knee extensor strength (R2 = 1.0) as significant prognostic variables. For hip-and-knee–targeted exercise, we identified older age (R2= 0.37), greater mass (R2= 0.28), and greater baseline hip abduction torque (R2= 1.0) as significant prognostic variables. We also identified a significant mechanistic association between pain and increased knee extensor torque (R2= 0.99). For hip-targeted exercise, we identified lower height as a significant prognostic variable (R2= 0.96-0.99) and a significant mechanistic association between both pain and function and increased hip abduction (R2= 0.93-0.96) and hip external rotation (R2= 0.96-0.97) strength.
Conclusions Prolonged symptom duration, older age, and greater mass are prognostic variables for people with PFP. Increasing hip and knee muscle strength may be mechanisms underpinning positive responses to exercise therapy.

Question 5

Best practice guide for patellofemoral pain based on synthesis of a systematic review, the patient voice and expert clinical reasoning

Accepted Answer

Objective Define a best practice guide for managing people with patellofemoral pain (PFP).
Methods A mixed-methods convergent segregated synthesis of meta-analysed data with a thematic analysis of semistructured interviews and focus groups. Agreement between subproject results informed the strength of clinical recommendation for interventions eligible for best practice recommendation.
Data sources Medline, Web of Science, Scopus, reference lists and citation tracking; semistructured interviews of people with PFP; and semistructured interviews and focus groups with clinical experts.
Eligibility criteria High-quality (PEDro scale >7) randomised controlled trials (RCTs) were retained for efficacy estimation using meta-analysis. People with PFP were required to have experienced an episode of care in the past 6 months and clinical experts were required to have>5 years of clinical experience alongside direct involvement in research.
Results Data from 65 high-quality RCTs involving 3796 participants informed 11 meta-analyses of interventions. Interviews with 12 people with PFP led to 3 themes and interviews with 19 clinical experts led to 4 themes. These were further explored in three clinical expert focus groups. Best practice for PFP should first involve understanding a patient’s background risk factors, their reasons for seeking care, greatest symptoms, and physical impairments, to inform treatment selection. Synthesis led to six distinct interventions being recommended. Knee-targeted±hip-targeted exercise therapy underpinned by education should be delivered, with additional supporting interventions such as prefabricated foot orthoses, manual therapy, movement/running retraining, or taping decided on and tailored to a patient’s needs and preferences.
Conclusion A best practice guide based on a synthesis of three data streams recommends that exercise therapy and education be delivered as the primary intervention for people with PFP. Prescription of other supporting interventions should be aligned with the individual patient’s particular presentation following a thorough assessment.

Question 6

The effects of a two-week neuromuscular intervention on biopsychosocial variables in people with patellofemoral pain: an observational study

Accepted Answer

May 2023
 Introduction: Patellofemoral pain (PFP) is common and predominately affects active populations. Altered biomechanics and psychosocial variables have been reported in people with PFP, but the effects of neuromuscular exercise on these variables is unknown. We aimed to investigate changes in biopsychosocial measures following a two-week neuromuscular intervention in people with PFP.
Materials and Methods: We measured pain (visual analogue scale), function (Kujala), activity level (Tegner), psychological well-being (Orebro), lower-limb isometric strength (handheld dynamometry), three-dimensional (3D) lower limb kinematics, and surface electromyography (sEMG), in people with PFP. 3D lower-limb kinematics and sEMG were synchronously sampled during step-up, step-down, and overground running. All measures were repeated after participants had completed a two-week neuromuscular intervention consisting of three exercises completed once per day, five days per week.
Results: 18 participants completed pre/post testing (60% females, mean age 30.6 years ±7.0, height 173.4cm ±10.4, mass 70.2kg ±12.4, symptom duration 39.0 months ±58.8), with three of 21 participants lost to follow-up. Across all clinical measures (muscle onsets, muscle activation and kinematics), the 95% bootstrapped confidence intervals (CI) of the mean difference contained the null hypothesis following the two-week neuromuscular intervention, indicating no significant differences.
Conclusion: A two-week neuromuscular intervention did not change biomechanical or psychosocial measures in people with PFP. Interventions with a longer duration or greater load magnitude are required to fully evaluate the biopsychosocial mechanisms of effect for exercise in people with PFP.

Question 7

Kinematic and kinetic gait characteristics in people with Patellofemoral Pain: a systematic review and Meta-analysis

Accepted Answer

February 2023
Background: Patellofemoral pain (PFP) is a prevalent knee condition with many proposed biomechanically orientated etiological factors and treatments.
Objective: We aimed to systematically review and synthesize the evidence for biomechanical variables (spatiotemporal, kinematic, kinetic) during walking and running in people with PFP compared with pain-free controls, and determine if biomechanical variables contribute to the development of PFP.
Design: Systematic review and meta-analysis.
Data sources: We searched Medline, CINAHL, SPORTDiscus, Embase, and Web of Science from inception to October 2021.
Eligibility criteria for selecting studies: All study designs (prospective, case–control [± interventional component, provided pre-intervention data were reported for both groups], cross-sectional) comparing spatiotemporal, kinematic, and/or kinetic variables during walking and/or running between people with and without PFP.
Results: We identified 55 studies involving 1300 people with PFP and 1393 pain-free controls. Overall pooled analysis identified that people with PFP had slower gait velocity [moderate evidence, standardized mean difference (SMD) − 0.50, 95% confidence interval (CI) − 0.72, − 0.27], lower cadence (limited evidence, SMD − 0.43, 95% CI − 0.74, − 0.12), and shorter stride length (limited evidence, SMD − 0.46, 95% CI − 0.80, − 0.12). People with PFP also had greater peak contralateral pelvic drop (moderate evidence, SMD − 0.46, 95% CI − 0.90, − 0.03), smaller peak knee flexion angles (moderate evidence, SMD − 0.30, 95% CI − 0.52, − 0.08), and smaller peak knee extension moments (limited evidence, SMD − 0.41, 95% CI − 0.75, − 0.07) compared with controls. Females with PFP had greater peak hip flexion (moderate evidence, SMD 0.83, 95% CI 0.30, 1.36) and rearfoot eversion (limited evidence, SMD 0.59, 95% CI 0.03, 1.14) angles compared to pain-free females. No significant between-group differences were identified for all other biomechanical variables. Data pooling was not possible for prospective studies.
Conclusion: A limited number of biomechanical differences exist when comparing people with and without PFP, mostly characterized by small-to-moderate effect sizes. People with PFP ambulate slower, with lower cadence and a shortened stride length, greater contralateral pelvic drop, and lower knee flexion angles and knee extension moments. It is unclear whether these features are present prior to PFP onset or occur as pain-compensatory movement strategies given the lack of prospective data.

Question 8

Body fat and skeletal muscle mass, but not body mass index, are associated with pressure hyperalgesia in young adults with patellofemoral pain

Accepted Answer

August 2022
Background: Young adults with patellofemoral pain (PFP) have a high prevalence of being overweight or obese, which is associated with impaired lower limb function and muscle weakness. However, the impact of being overweight or obese on pain sensitivity has not been explored.
Objectives: We investigated the association between body fat, skeletal muscle mass, and body mass index (BMI) with pressure hyperalgesia and self-reported pain in young adults with PFP.
Methods: 114 adults with PFP (24 ± 5 years old, 62% women) were recruited. Demographics and self-reported pain (current and worst knee pain intensity in the previous month - 0–100 mm visual analog scale) were recorded. Body fat and skeletal muscle mass were measured using bioelectrical impedance. Pressure hyperalgesia was measured using a handheld algometer (pressure pain threshold) at three sites: center of patella of the painful knee, ipsilateral tibialis anterior, and contralateral upper limb. The association between body fat, skeletal muscle mass, and BMI with pressure hyperalgesia and self-reported pain were investigated using partial correlations and hierarchical regression models (adjusted for sex, bilateral pain, and symptoms duration).
Results: Higher body fat and lower skeletal muscle mass were associated with local, spread, and widespread pressure hyperalgesia (ΔR2=0.09 to 0.17, p ≤ 0.001; ΔR2=0.14 to 0.26, p<0.001, respectively), and higher current self-reported pain (ΔR2=0.10, p<0.001; ΔR2=0.06, p = 0.007, respectively). Higher BMI was associated with higher current self-reported pain (ΔR2=0.10, p = 0.001), but not with any measures of pressure hyperalgesia (p>0.05).
Conclusion: Higher body fat and lower skeletal muscle mass help to explain local, spread, and widespread pressure hyperalgesia, and self-reported pain in people with PFP. BMI only helps to explain self-reported pain. These factors should be considered when assessing people with PFP and developing their management plan, but caution should be taken as the strength of association was generally low.

Question 9

Six treatments have positive effects at three-months for people with patellofemoral pain: a systematic review with meta-analysis

Accepted Answer

September 2022 Objective: To determine the effects of non-surgical treatments on pain and function in people with patellofemoral pain (PFP). Design: Systematic review with meta-analysis. Literature Search: We searched Medline, Web of Science, and Scopus to May 2022 for interventional randomised controlled trials (RCTs) in people with PFP. Study Selection Criteria: We included RCTs that were scored >7 on the PEDro scale. Data Synthesis: We extracted homogenous pain and function data at short- (<3 months), medium- (>3 to <12 months) and long-term (>12 months) follow up. Interventions demonstrated primary efficacy if outcomes were superior to sham, placebo, or wait-and-see control. Interventions demonstrated secondary efficacy if outcomes were superior to an intervention with primary efficacy. Results: We included 65 RCTs. Four interventions demonstrated short-term primary efficacy: knee-targeted exercise therapy for pain (SMD 1.16, 95% CI 0.66, 1.66) and function (SMD 1.19, 95% CI 0.51, 1.88), combined interventions for pain (SMD 0.79, 95% CI 0.26, 1.29) and function (SMD 0.98, 95% CI 0.47, 1.49), foot orthoses for global rating of change (OR 4.31, 95% CI 1.48, 12.56), and lower-quadrant manual therapy for pain (SMD 2.30, 95% CI 1.60, 3.00). Two interventions demonstrated short-term secondary efficacy compared to knee-targeted exercise therapy: hip-and-knee-targeted exercise therapy for pain (SMD 1.02, 95% CI 0.58,1.46) and function (SMD 1.03, 95% CI 0.61, 1.45), and knee-targeted exercise therapy and perineural dextrose injection for pain (SMD 1.34, 95% CI 0.72, 1.95) and function (SMD 1.21, 95% CI 0.60, 1.82). Conclusion: Six interventions had positive effects at three-months for people with PFP, with no intervention adequately tested beyond this timepoint.

Question 10

Clinicians’ experience of the diagnosis and management of patellofemoral pain: A qualitative exploration

Accepted Answer

April 2022
Background: Patellofemoral pain (PFP) is common and has a poor long-term prognosis. There is a lack of clarity about the clinical reasoning of recognised inter-disciplinary experts in the published literature.
Objectives: To help identify best practice by exploring the clinical reasoning of a range of inter-disciplinary experts that regularly diagnose and treat PFP.
Design: Qualitative study with semi-structured interviews.
Method: Recruitment resulted in a convenience sample for semi-structured interview, which were recorded and transcribed verbatim. Data were analysed until theoretical saturation, as determined by multiple investigators.
Findings: Interviews with 19 clinical experts (15 men, 4 women; mean experience 18.6 years ± 8.6) from four broad professions yielded four themes. Firstly, the assessment and diagnosis process should include a thorough history and examination to rule in PFP. Secondly, information provision should aim to increase patients’ understanding, aid in controlling symptoms, and facilitate behaviour change. Thirdly, active rehabilitation, which was a salient theme and included advocacy of combined hip and knee exercise that is adapted to the individual. Finally, treatment adjuncts, which can be used selectively to modify symptoms, may include running retraining, taping, or foot orthoses.
Conclusions: PFP should be diagnosed clinically, and tailored treatment programmes should be prescribed for people with PFP. Exercise was considered the most effective treatment and underlying psychological factors should be addressed to improve prognosis.

Question 11

Patient experience of the diagnosis and management of patellofemoral pain: A qualitative exploration

Accepted Answer

February 2022
Background: Patellofemoral pain (PFP) is common and long-term treatment outcomes are unsatisfactory. Qualitative exploration of diagnosis and management from the perspective of people with PFP is lacking.
Objectives: To inform care and improve intervention delivery by exploring the experience of people with PFP regarding diagnosis and management.
Design: Qualitative study with semi-structured interviews.
Method: Online recruiting yielded a convenience sample of participants with PFP for semi-structured interview. Interviews were recorded, transcribed verbatim, and analysed using thematic analysis until theoretical saturation by multiple investigators to determine themes and sub-themes.
Results: 12 participants were interviewed, with three themes identified; the value of diagnosis, the need for tailored (individualised) care, and the role of education. Participants viewed receiving a diagnosis as essential to guide management, yet one was rarely provided, causing uncertainty about pain mechanisms; “it's nice to be told what it is that's wrong”. Interventions needed to be tailored to the individual as not all participants responded in the same way to treatment(s) or had the same needs; “everyone copes and reacts differently”. Finally, participants viewed education as essential to empower them to understand and manage the condition; “if I'd have been given more information, I think I'd know how to deal with it more”.
Conclusions: The overarching narrative from three themes was a desire for clearly communicated personalised care that meets individual needs. People with PFP desire a diagnosis to explain their pain, tailored interventions, and appropriate education to optimise their experience and outcomes.

Question 12

Local neuromuscular characteristics associated with patellofemoral pain: A systematic review and meta-analysis

Accepted Answer

December 2021
Background: Local neuromuscular deficits have been reported in people with patellofemoral pain. We synthesised the neuromuscular characteristics associated with patellofemoral pain to help identify interventional targets and potential mechanisms.
Methods: Five databases were searched for local neuromuscular characteristics in case-control studies. Electromyography, flexibility, muscle performance and cross-sectional area data were derived from functional or isolated task investigations and synthesised accordingly. An evidence gap map was constructed.
Findings: Sixty-seven studies were included. In functional tasks, electromyographic investigations showed moderate evidence of small effect for vastus medialis onset-delays relative to vastus lateralis (0.44 [0.03, 0.85]) during stepping/stair negotiation tasks, and higher biceps femoris mean excitation amplitudes (0.55 [0.06, 1.04]) in single-leg triple-hop test. In isolated tasks, we found moderate evidence of medium effect for lower Hoffman-reflex amplitude of vastus medialis (−1.12 [−1.56, −0.67]). Muscle performance investigations showed; strong evidence with medium and small effects for lower extensors concentric (−0.61 [−0.81, −0.40]) and eccentric (−0.56 [−0.79, −0.33]) strength, and moderate evidence of medium effect of lower isometric (−0.64 [−0.87, −0.41]) strength, moderate evidence with small effect for rate of force development to 30% (−0.55[−0.89, −0.21]), 60% (−0.57[−0.90, −0.25]) and medium effect to 90% (−0.76[−1.43, −0.10]) of maximum voluntary contraction, and small effect for lower flexors concentric strength (−0.46 [−0.74, −0.19]) and extensors total work (−0.48 [−0.90, −0.07]). Flexibility investigations showed tighter hamstrings (−0.57 [−0.99, −0.14]).
Interpretation: Differences within quadriceps and hamstrings motor-control, hamstrings tightness, and quadriceps and hamstrings weakness are associated with patellofemoral pain, and can be used to guide investigations of treatment effects.

Question 13

REPORT-PFP: a consensus from the International Patellofemoral Research Network to improve REPORTing of quantitative PatelloFemoral Pain studies

Accepted Answer

June 2021
Patellofemoral pain is a common and often debilitating musculoskeletal condition. Clinical translation and evidence synthesis of patellofemoral pain research are compromised by heterogenous and often inadequately reported study details. This consensus statement and associated checklist provides standards for REPORTing of quantitative PatelloFemoral Pain (REPORT-PFP) research to enhance clinical translation and evidence synthesis, and support clinician engagement with research and data collection. A three-stage Delphi process was initiated at the 2015 International Patellofemoral Research Network (iPFRN) retreat. An initial e-Delphi activity (n=24) generated topics and items, which were refined at the 2017 iPFRN retreat, and voted on prior to and following the 2019 iPFRN retreat (n=51 current and past retreat participants). Voting criteria included ‘strongly recommended’ (essential), ‘recommended’ (encouraged) and uncertain/unsure. An item was included in the checklist if ≥70% respondents voted ‘recommended’. Items receiving ≥70% votes for ‘strongly recommended’ were labelled as such. The final REPORT-PFP checklist includes 31 items (11 strongly recommended, 20 recommended), covering (i) demographics (n=2,4); (ii) baseline symptoms and previous treatments (n=3,7); (iii) outcome measures (2,4); (iv) outcomes measure description (n=1,2); (v) clinical trial methodology (0,3) and (vi) reporting study results (n=3,0). The REPORT-PFP checklist is ready to be used by researchers and clinicians. Strong stakeholder engagement from clinical academics during development means consistent application by the international patellofemoral pain research community is likely. Checklist adherence will improve research accessibility for clinicians and enhance future evidence synthesis.

Question 14

Is markerless, smart phone recorded two-dimensional video a clinically useful measure of relevant lower limb kinematics in runners with patellofemoral pain? A validity and reliability study

Accepted Answer

May 2020
Objectives: Investigate the validity and reliability of markerless, smart phone collected, two-dimensional (2D) video, analysed using the ‘Hudl technique’ application, compared to three-dimensional (3D) kinematics during running, in participants with patellofemoral pain (PFP).
Design: Validity/reliability study.
Setting: Biomechanics laboratory.
Participants: Males/females with PFP (n = 21, 10 males, 11 females, age 32.1 months [±12.9]).
Main outcome measures: Manually synchronised 2D and 3D measurement of peak hip adduction (HADD) and peak knee flexion (KFLEX) during running.
Results: 2D and 3D measures of peak KFLEX (p = 0.02, d = 1.13), but not peak HADD (p = 0.25, d = −0.27), differed significantly. Poor validity was identified for 2D measurement of peak HADD (ICC 0.06, 95% CI -0.35, 0.47) and peak KFLEX ICC 0.42, 95% CI (−0.10, 0.75). Moderate intra-rater reliability was identified for both variables (ICC 0.61–65), alongside moderate inter-rater reliability for peak KFLEX (ICC 0.71) and poor inter-rater reliability for peak HADD (ICC 0.31).
Conclusions: Measurement of peak HADD and KFLEX in runners with PFP using markerless, smart phone collected 2D video, analysed using the Hudl technique Application is invalid, with poor to moderate reliability. Investigation of alternate 2D video approaches to increase precision is warranted. At present, 2D video analysis of running using Hudl Technique cannot be advocated.

Question 15

Two Weeks of Wearing a Knee Brace Compared With Minimal Intervention on Kinesiophobia at 2 and 6 Weeks in People With Patellofemoral Pain: A Randomized Controlled Trial

Accepted Answer

April 2020
Objective: To investigate the effect of a knee brace compared with minimal intervention on self-reported kinesiophobia and function, objective function, and physical activity level in people with patellofemoral pain (PFP).
Design: Single-blind randomized controlled trial (1:1), parallel.
Participants: Individuals with PFP (N=50).
Main Outcome Measures: Primary - kinesiophobia (Tampa Scale for Kinesiophobia). Secondary - self-reported function (Anterior Knee Pain Scale), physical activity level (International Physical Activity Questionnaire), and objective function (forward step-down test). Outcomes were assessed at baseline (T0), at the end of the intervention (2wk) (T1), and at 6 weeks after baseline (T2).
Intervention: Participants were randomly assigned to 1 of 2 interventions groups: (1) use of knee brace for 2 weeks during daily living, sports, or painful tasks (brace group) and (2) educational leaflet with information about PFP (leaflet group).
Results: The knee brace reduced kinesiophobia in people with PFP compared with minimal intervention with moderate effect size at T1=mean difference (95% CI) −5.56 (−9.18 to −1.93) and T2=−5.24 (−8.58 to −1.89). There was no significant difference in self-reported and objective function and physical activity level.
Conclusions: The knee brace improved kinesiophobia immediately after intervention (at 2wk) and at 6-week follow-up in people with PFP compared with minimal intervention. A knee brace may be considered within clinically reasoned paradigms to facilitate exercise therapy interventions for people with PFP.

Question 16

Gait Retraining as an Intervention for Patellofemoral Pain

Accepted Answer

March 2020
Purpose of Review: Movement retraining in rehabilitation is the process by which a motor program is changed with the overall goal of reducing pain or injury risk. Movement retraining is an important component of interventions to address patellofemoral pain. The purpose of this paper is to review the methods and results of current retraining studies that are aimed at reducing symptoms of patellofemoral pain.
Recent Findings: The majority of studies reviewed demonstrated some improvement in patellofemoral pain symptoms and overall function. However, the degree of improvement as well as the persistence of improvement over time varied between studies. The greatest pain reduction and persistent changes were noted in those studies that incorporated a faded feedback design including between 8 and 18 sessions over 2–6 weeks, typically 3–4 sessions per week. Additionally, dosage in these studies increased to 30–45 min during later sessions, resulting in 177–196 total minutes of retraining. In contrast, pain reductions and persistence of changes were the least in studies where overall retraining volume was low and feedback was either absent or continual.
Summary: Faulty movement patterns have been associated with patellofemoral pain. Studies have shown that strengthening alone does not alter these patterns, and that addressing the motor program is needed to effect these changes. Based upon the studies reviewed here, retraining faulty patterns, when present, appears to play a significant role in addressing patellofemoral pain. Therefore, movement retraining, while adhering to basic motor control principles, should be part of a therapist’s intervention skillset when treating patients with PFP.

Question 17

Altered pain processing and sensitisation is evident in adults with patellofemoral pain: a systematic review including meta-analysis and meta-regression

Accepted Answer

September 2019
 Background: Previous systematic reviews have reported manifestations of pain sensitisation as a feature of painful knee disorders, in particular osteoarthritis, with moderate evidence for pain sensitisation in patellofemoral pain (PFP). However, despite past studies recruiting female mostly adolescent PFP patients, it is unclear if sex or age plays a role. Investigation is required to determine if altered pain processing is a key feature of PFP and if a subgroup of patients is at an increased risk to help provide targeted management. The primary aim of this systematic review was to examine evidence investigating pain processing in PFP. Secondary aims were to evaluate the relationship between pain processing and (1) sex, (2) age and (3) symptom duration.
Methods: The protocol was prospectively registered with PROSPERO (CRD42019129851). PubMed, CINAHL, Web of Science and EMBASE were systematically searched from inception to April 2019 for studies investigating pain processing in PFP patients compared to controls using quantitative sensory testing. Each included paper was assessed for methodological quality using a modified version of Downs and Black. Means and standard deviations were extracted to calculate standardised mean differences (SMD) and 95% confidence intervals (95% CI). Where possible meta-analysis and meta-regression were performed using a random effects model.
Results: Eleven studies were identified, two medium and nine high quality. Meta-analysis indicates moderate evidence for decreased pressure pain thresholds (SMD −0.68, 95% CI −0.93 to −0.43), increased tactile detection thresholds (SMD 1.35, 95% CI 0.49–2.22) and increased warmth detection thresholds (SMD 0.61, 95% CI 0.30–0.92) in PFP patients compared to controls. Secondary analysis indicates moderate evidence for decreased pressure pain thresholds in female compared to male patients (SMD −0.75, 95% CI −1.34 to −0.16). Meta-regression indicates a moderate correlation between decreasing local and distal pressure pain thresholds and decreasing patient age (local R2 = 0.556, p = 0.0211; distal R2 = 0.491, p = 0.0354) but no correlation with symptom duration (p > 0.05).
Conclusions: Evidence from this systematic review with meta-analysis and meta-regression appears to suggest the presence of altered pain processing and sensitisation in patients with PFP with increased sensitivity indicated in female patients and younger patients.Implications: With evidence of altered pain processing and sensitisation in PFP, it may be beneficial for clinicians to consider management approaches that aim specifically at addressing neuropathic pain, for example neuroscience education, to improve patients outcomes. With female patients and younger patients indicated as experiencing greater degree of sensitivity, this may be a good demographic to start screening for sensitisation, in order to better identify and treat those most affected.

Question 18

Pressure pain thresholds in adults with patellofemoral pain and patellofemoral joint osteoarthritis: a case-control study

Accepted Answer

June 2019
 Background: Patellofemoral pain (PFP) and patellofemoral joint osteoarthritis (PFJOA) are common non-self-limiting conditions causing significant pain and disability. The underlying pain pathologies lack consensus with evidence suggesting reduced pressure pain thresholds (PPTs) in adolescent females with PFP and individuals with knee osteoarthritis. A paucity of evidence exists for mixed-sex adults with PFP and PFJOA in isolation. Exploring if pain sensitisation is a dominant feature of PFP and PFJOA may have important implications for the delivery of a patient centred management approach. The primary aim was to measure local and remote PPTs in PFP and PFJOA patients compared to matched controls. Secondary aims were to evaluate the relationship between PPTs and (1) condition severity and (2) knee function.
Methods: 13 PFP patients plus 20 matched controls and 15 PFJOA patients plus 34 matched controls were recruited from a UK mixed-sex adult population. Controls were matched on age, sex and activity level. Demographic details, Tegner activity level score, symptom duration, condition severity (Kujala and KOOS-PF scores for PFP and PFJOA, respectively) and knee function (Modified Whatman score rating of five single leg squats) were recorded. PPTs were measured at six sites: five local around the knee, one remote on the contralateral leg. Between-group differences were tested using a two-way mixed model analysis of variance with repeated measures. Strength of association between PPTs and condition severity and knee function were tested using Spearman’s rank order correlation.
Results: No statistically significant difference in PPTs were observed between the PFP patients [F(1,31) = 0.687, p = 0.413, η2 = 0.022] or PFJOA patients [F(1,47) = 0.237, p = 0.629, η2 = 0.005] and controls. Furthermore, no correlation was found between PPTs and condition severity or knee function in PFP or PFJOA (p > 0.05).
Conclusions: Results suggest mechanical pain sensitisation is not a dominant feature of UK mixed-sex adults with PFP or PFJOA.Implications: PFP and PFJOA remain persistent pain complaints which may not be well explained by objective measures of sensitivity such as PPTs. The findings suggest that peripheral pain processing changes leading to pain sensitisation is not a key feature in PFP or PFJOA. Instead the underlying pain pathway is likely to remain primary nociceptive, possibly with a subgroup of patients who experience pain sensitisation and might benefit from a more targeted management approach.

Question 19

Increased hip adduction during running is associated with patellofemoral pain and differs between males and females: A case-control study

Accepted Answer

June 2019
Patellofemoral pain is common amongst recreational runners and associated with altered running kinematics. However, it is currently unclear how sex may influence kinematic differences previously reported in runners with patellofemoral pain. This case-control study aimed to evaluate lower limb kinematics in males and females with and without patellofemoral pain during running. Lower limb 3D kinematics were assessed in 20 runners with patellofemoral pain (11 females, 9 males) and 20 asymptomatic runners (11 females, 9 males) during a 3 km treadmill run. Variables of interest included peak hip adduction, internal rotation and flexion angles; and peak knee flexion angle, given their previously reported association with patellofemoral pain. Age, height, mass, weekly run distance and step rate were not significantly different between groups. Mixed-sex runners with patellofemoral pain were found to run with a significantly greater peak hip adduction angle (mean difference = 4.9°, d = 0.91, 95% CI 1.4–8.2, p = 0.01) when compared to matched controls, but analyses for all other kinematic variables were non-significant. Females with patellofemoral pain ran with a significantly greater peak hip adduction angle compared to female controls (mean difference = 6.6°, p = 0.02, F = 3.41, 95% CI 0.4–12.8). Analyses for all other kinematic variables between groups (males and females with/without PFP) were non-significant. Differences in peak hip adduction between those with and without patellofemoral pain during running appear to be driven by females. This potentially highlights different kinematic treatment targets between males and females. Future research is encouraged to report lower limb kinematic variables in runners with patellofemoral pain separately for males and females.

Question 20

Risk factors for patellofemoral pain: a systematic review & meta-analysis.

Accepted Answer

September 2018
Background: Patellofemoral pain (PFP) is a prevalent condition commencing at various points throughout life. We aimed to provide an evidence synthesis concerning predictive variables for PFP, to aid development of preventative interventions.
Methods: We searched Medline, Web of Science and SCOPUS until February 2017 for prospective studies investigating at least one potential risk factor for future PFP. Two independent reviewers appraised methodological quality using the Newcastle–Ottawa Scale. We conducted meta-analysis where appropriate, with standardised mean differences (SMD) and risk ratios calculated for continuous and nominal scaled data.
Results: This review included 18 studies involving 4818 participants, of whom 483 developed PFP (heterogeneous incidence 10%). Three distinct subgroups (military recruits, adolescents and recreational runners) were identified. Strong to moderate evidence indicated that age, height, weight, body mass index (BMI), body fat and Q angle were not risk factors for future PFP. Moderate evidence indicated that quadriceps weakness was a risk factor for future PFP in the military, especially when normalised by BMI (SMD −0.69, CI −1.02, –0.35). Moderate evidence indicated that hip weakness was not a risk factor for future PFP (multiple pooled SMDs, range −0.09 to −0.20), but in adolescents, moderate evidence indicated that increased hip abduction strength was a risk factor for future PFP (SMD 0.71, CI 0.39, 1.04).
Conclusions: This review identified multiple variables that did not predict future PFP, but quadriceps weakness in military recruits and higher hip strength in adolescents were risk factors for PFP. Identifying modifiable risk factors is an urgent priority to improve prevention and treatment outcomes.

Question 21

Medial and Lateral Patellofemoral Joint Retinaculum Thickness in People With Patellofemoral Pain: A Case‐Control Study

Accepted Answer

September 2018
Objectives: To measure the medial and lateral retinaculum thickness in individuals with and without patellofemoral pain using ultrasound and to assess associations with the symptom duration and function.
Methods: Medial and lateral patellofemoral joint retinaculum thicknesses of 32 knees (16 with patellofemoral pain and 16 asymptomatic) were measured with B‐mode ultrasound at 0.5, 1, and 1.5 cm from the patella border. Participants with patellofemoral pain completed a Kujala questionnaire, and both groups underwent a single‐leg squat performance assessment. Two‐way analyses of variance (site × group) determined the overall effect, and Cohen d values were calculated to describe the magnitude of the difference for each measurement.
Results: The groups were matched for age, height, and weight. Compared to controls, participants with patellofemoral pain had thicker lateral (overall effect, P  = .03) and medial (overall effect, P  < 0.01) retinacula. No correlations between retinaculum thickness and Kujala scores (lateral retinaculum, r  = 0.106 [0.5 cm], –0.093 [1 cm], and –0.207 [1.5 cm]; and medial retinaculum, r  = 0.059, 0.109, and –0.219), symptom duration (lateral retinaculum, r  = 0.001, –0.041, and 0.302; and medial retinaculum, r  = –0.027, –0.358, and –0.346), or single‐leg squat performance scores (lateral retinaculum, r  = 0.051, 0.114, and 0.046; and medial retinaculum, r  = –0.119, –0.292, and 0.011) were observed.
Conclusions: Increased lateral and medial retinaculum thickness in individuals with patellofemoral pain compared to controls identifies structural changes that may be associated with the pathogenesis of patellofemoral pain. The absence of a significant correlation between retinaculum thickness and the symptom duration or function further shows a lack of an association between structure and function in individuals with patellofemoral pain.

Question 22

How to manage patellofemoral pain – Understanding the multifactorial nature and treatment options

Accepted Answer

July 2018
Patellofemoral pain (PFP) is one of the most prevalent conditions within sports medicine, orthopaedic and general practice settings. Long-term treatment outcomes are poor, with estimates that more than 50% of people with the condition will report symptoms beyond 5 years following diagnosis. Additionally, emerging evidence indicates that PFP may be on a continuum with patellofemoral osteoarthritis. Consensus of world leading clinicians and academics highlights the potential benefit of delivering tailored interventions, specific to an individual's needs, to improve patient outcome. This clinical masterclass aims to develop the reader's understanding of PFP aetiology, inform clinical assessment and increase knowledge regarding individually tailored treatment approaches. It offers practical application guidance, and additional resources, that can positively impact clinical practice.

Question 23

The effects & mechanisms of increasing running step rate: A feasibility study in a mixed-sex group of runners with patellofemoral pain

Accepted Answer

July 2018
Objectives: To explore feasibility of recruitment and retention of runners with patellofemoral pain (PFP), before delivering a step rate intervention.
Design: Feasibility study.
Setting: Human performance laboratory.
Participants: A mixed-sex sample of runners with PFP (n = 11).
Main outcome measures: Average/worst pain and the Kujala Scale were recorded pre/post intervention, alongside lower limb kinematics and surface electromyography (sEMG), sampled during a 3 KM treadmill run.
Results: Recruitment and retention of a mixed-sex cohort was successful, losing one participant to public healthcare and with kinematic and sEMG data lost from single participants only. Clinically meaningful reductions in average (MD = 2.1, d = 1.7) and worst pain (MD = 3.9, d = 2.0) were observed. Reductions in both peak knee flexion (MD = 3.7°, d = 0.78) and peak hip internal rotation (MD = 5.1°, d = 0.96) were observed, which may provide some mechanistic explanation for the identified effects. An increase in both mean amplitude (d = 0.53) and integral (d = 0.58) were observed for the Vastus Medialis Obliqus (VMO) muscle only, of questionable clinical relevance.
Conclusions: Recruitment and retention of a mixed sex PFP cohort to a step rate intervention involving detailed biomechanical measures is feasible. There are indications of both likely efficacy and associated mechanisms. Future studies comparing the efficacy of different running retraining approaches are warranted.

Question 24

Runners with patellofemoral pain have altered biomechanics which targeted interventions can modify: A systematic review and meta-analysis

Accepted Answer

March 2016
Patellofemoral pain (PFP) is the most prevalent running pathology and associated with multi-level biomechanical factors. This systematic review aims to guide treatment and prevention of PFP by synthesising prospective, observational and intervention studies that measure clinical and biomechanical outcomes in symptomatic running populations. Medline, Web of Science and CINAHL were searched from inception to April 2015 for prospective, case-control or intervention studies in running-related PFP cohorts. Study methodological quality was scored by two independent raters using the modified Downs and Black or PEDro scales, with meta-analysis performed where appropriate. 28 studies were included. Very limited evidence indicates that increased peak hip adduction is a risk factor for PFP in female runners, supported by moderate evidence of a relationship between PFP and increased peak hip adduction, internal rotation and contralateral pelvic drop, as well as reduced peak hip flexion. Limited evidence was also identified that altered peak force and time to peak at foot level is a risk factor for PFP development. Limited evidence from intervention studies indicates that both running retraining and proximal strengthening exercise lead to favourable outcomes in both pain and function, but only running retraining significantly reduces peak hip adduction, suggesting a possible kinematic mechanism. Put together, these findings highlight limited but coherent evidence of altered biomechanics which interventions can alter with resultant symptom change in females with PFP. There is a clear need for high quality prospective studies of intervention efficacy with measurement of explanatory mechanisms.

Question 25

Running retraining to treat lower limb injuries: a mixed-methods study of current evidence synthesised with expert opinion

Accepted Answer

February 2016
Importance: Running-related injuries are highly prevalent.Objective: Synthesise published evidence with international expert opinion on the use of running retraining when treating lower limb injuries.
Design: Mixed methods.
Methods: A systematic review of clinical and biomechanical findings related to running retraining interventions were synthesised and combined with semistructured interviews with 16 international experts covering clinical reasoning related to the implementation of running retraining.
Results: Limited evidence supports the effectiveness of transition from rearfoot to forefoot or midfoot strike and increase step rate or altering proximal mechanics in individuals with anterior exertional lower leg pain; and visual and verbal feedback to reduce hip adduction in females with patellofemoral pain. Despite the paucity of clinical evidence, experts recommended running retraining for: iliotibial band syndrome; plantar fasciopathy (fasciitis); Achilles, patellar, proximal hamstring and gluteal tendinopathy; calf pain; and medial tibial stress syndrome. Tailoring approaches to each injury and individual was recommended to optimise outcomes. Substantial evidence exists for the immediate biomechanical effects of running retraining interventions (46 studies), including evaluation of step rate and strike pattern manipulation, strategies to alter proximal kinematics and cues to reduce impact loading variables.
Summary and relevance: Our synthesis of published evidence related to clinical outcomes and biomechanical effects with expert opinion indicates running retraining warrants consideration in the treatment of lower limb injuries in clinical practice.

Question 26

Proximal muscle rehabilitation is effective for patellofemoral pain: a systematic review with meta-analysis

Accepted Answer

November 2015
Background: Proximal muscle rehabilitation is commonly prescribed to address muscle strength and function deficits in individuals with patellofemoral pain (PFP). This review (1) evaluates the efficacy of proximal musculature rehabilitation for patients with PFP; (2) compares the efficacy of various rehabilitation protocols; and (3) identifies potential biomechanical mechanisms of effect in order to optimise outcomes from proximal rehabilitation in this problematic patient group.
Methods: Web of Knowledge, CINAHL, EMBASE and Medline databases were searched in December 2014 for randomised clinical trials and cohort studies evaluating proximal rehabilitation for PFP. Quality assessment was performed by two independent reviewers. Effect size calculations using standard mean differences and 95% CIs were calculated for each comparison.
Results: 14 studies were identified, seven of high quality. Strong evidence indicated proximal combined with quadriceps rehabilitation decreased pain and improved function in the short term, with moderate evidence for medium-term outcomes. Moderate evidence indicated that proximal when compared with quadriceps rehabilitation decreased pain in the short-term and medium-term, and improved function in the medium term. Limited evidence indicated proximal combined with quadriceps rehabilitation decreased pain more than quadriceps rehabilitation in the long term. Very limited short-term mechanistic evidence indicated proximal rehabilitation compared with no intervention decreased pain, improved function, increased isometric hip strength and decreased knee valgum variability while running.
Conclusions: A robust body of work shows proximal rehabilitation for PFP should be included in conservative management. Importantly, greater pain reduction and improved function at 1 year highlight the long-term value of proximal combined with quadriceps rehabilitation for PFP.

Question 27

The ‘Best Practice Guide to Conservative Management of Patellofemoral Pain’: incorporating level 1 evidence with expert clinical reasoning

Accepted Answer

February 2015
Importance: Patellofemoral pain (PFP) is both chronic and prevalent; it has complex aetiology and many conservative treatment options.Objective: Develop a comprehensive contemporary guide to conservative management of PFP outlining key considerations for clinicians to follow.Design: Mixed methods.Methods: We synthesised the findings from six high-quality systematic reviews to September 2013 with the opinions of 17 experts obtained via semistructured interviews. Experts had at least 5 years clinical experience with PFP as a specialist focus, were actively involved in PFP research and contributed to specialist international meetings. The interviews covered clinical reasoning, perception of current evidence and research priorities.Results: Multimodal intervention including exercise to strengthen the gluteal and quadriceps musculature, manual therapy and taping possessed the strongest evidence. Evidence also supports use of foot orthoses and acupuncture. Interview transcript analysis identified 23 themes and 58 subthemes. Four key over-arching principles to ensure effective management included—(1) PFP is a multifactorial condition requiring an individually tailored multimodal approach. (2) Immediate pain relief should be a priority to gain patient trust. (3) Patient empowerment by emphasising active over passive interventions is important. (4) Good patient education and activity modification is essential. Future research priorities include identifying risk factors, testing effective prevention, developing education strategies, evaluating the influence of psychosocial factors on treatment outcomes and how to address them, evaluating the efficacy of movement pattern retraining and improving clinicians’ assessment skills to facilitate optimal individual prescription.
 Conclusions and relevance: Effective management of PFP requires consideration of a number of proven conservative interventions. An individually tailored multimodal intervention programme including gluteal and quadriceps strengthening, patellar taping and an emphasis on education and activity modification should be prescribed for patients with PFP. We provide a ‘Best Practice Guide to Conservative Management of Patellofemoral Pain’ outlining key considerations.

Question 28

Dynamic foot function as a risk factor for lower limb overuse injury: a systematic review

Accepted Answer

December 2014
Background: Dynamic foot function is considered a risk factor for lower limb overuse injuries including Achilles tendinopathy, shin pain, patellofemoral pain and stress fractures. However, no single source has systematically appraised and summarised the literature to evaluate this proposed relationship. The aim of this systematic review was to investigate dynamic foot function as a risk factor for lower limb overuse injury.
Methods: A systematic search was performed using Medline, CINAHL, Embase and SportDiscus in April 2014 to identify prospective cohort studies that utilised dynamic methods of foot assessment. Included studies underwent methodological quality appraisal by two independent reviewers using an adapted version of the Epidemiological Appraisal Instrument (EAI). Effects were expressed as standardised mean differences (SMD) for continuous scaled data, and risk ratios (RR) for nominal scaled data.
Results: Twelve studies were included (total n = 3,773; EAI 0.44 to 1.20 out of 2.00, representing low to moderate quality). There was limited to very limited evidence for forefoot, midfoot and rearfoot plantar loading variables (SMD 0.47 to 0.85) and rearfoot kinematic variables (RR 2.67 to 3.43) as risk factors for patellofemoral pain; and plantar loading variables (forefoot, midfoot, rearfoot) as risk factors for Achilles tendinopathy (SMD 0.81 to 1.08). While there were significant findings from individual studies for plantar loading variables (SMD 0.3 to 0.84) and rearfoot kinematic variables (SMD 0.29 to 0.62) as risk factors for ‘non-specific lower limb overuse injuries’, these were often conflicting regarding different anatomical regions of the foot. Findings from three studies indicated no evidence that dynamic foot function is a risk factor for iliotibial band syndrome or lower limb stress fractures.
Conclusion: This systematic review identified very limited evidence that dynamic foot function during walking and running is a risk factor for patellofemoral pain, Achilles tendinopathy, and non-specific lower limb overuse injuries. It is unclear whether these risk factors can be identified clinically (without sophisticated equipment), or modified to prevent or manage these injuries. Future prospective cohort studies should address methodological limitations, avoid grouping different lower limb overuse injuries, and explore clinically meaningful representations of dynamic foot function.

Question 29

Foot posture as a risk factor for lower limb overuse injury: a systematic review and meta-analysis

Accepted Answer

December 2014
Background: Static measures of foot posture are regularly used as part of a clinical examination to determine the need for foot level interventions. This is based on the premise that pronated and supinated foot postures may be risk factors for or associated with lower limb injury. This systematic review and meta-analysis investigates foot posture (measured statically) as a potential risk factor for lower limb overuse injuries.

Methods: A systematic search was performed using Medline, CINAHL, Embase, SportDiscus in April 2014, to identify prospective cohort studies that investigated foot posture and function as a risk factor for lower limb overuse injury. Eligible studies were classified based on the method of foot assessment: (i) static foot posture assessment; and/or (ii) dynamic foot function assessment. This review presents studies evaluating static foot posture. The methodological quality of included studies was evaluated by two independent reviewers, using an adapted version of the Epidemiological Appraisal Instrument (EAI). Where possible, effects were expressed as standardised mean differences (SMD) for continuous scaled data, and risk ratios (RR) for nominal scaled data. Meta-analysis was performed where injuries and outcomes were considered homogenous.

Results: Twenty-one studies were included (total n = 6,228; EAI 0.8 to 1.7 out of 2.0). There was strong evidence that a pronated foot posture was a risk factor for medial tibial stress syndrome (MTSS) development and very limited evidence that a pronated foot posture was a risk factor for patellofemoral pain development, although associated effect sizes were small (0.28 to 0.33). No relationship was identified between a pronated foot posture and any other evaluated pathology (i.e. foot/ankle injury, bone stress reactions and non-specific lower limb overuse injury).

Conclusions: This systematic review identified strong and very limited evidence of small effect that a pronated foot posture is a risk factor for MTSS and patellofemoral pain respectively. Evaluation of static foot posture should be included in a multifactorial assessment for both MTSS and patellofemoral pain, although only as a part of the potential injury risk profile. Whilst the included measures are clinically applicable, further studies are required to determine their relationship with dynamic foot function.

Question 30

The immediate effects of foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in individuals with patellofemoral pain

Accepted Answer

November 2014
Background: Evidence shows that anti-pronating foot orthoses improve patellofemoral pain, but there is a paucity of evidence concerning mechanisms. We investigated the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; (ii) electromyography variables of vastus medialis oblique, vastus lateralis and gluteus medius during a functional step-up task, and (iii) associated clinical measures.
Methods: Hip muscle activity and kinematics were measured during a step-up task with and without an anti-pronating foot orthoses, in people (n = 20, 9 M, 11 F) with patellofemoral pain. Additionally, we measured knee function, foot posture index, isometric hip abductor and knee extensor strength and weight-bearing ankle dorsiflexion.
Findings: Reduced hip adduction (0.82°, P = 0.01), knee internal rotation (0.46°, P = 0.03), and decreased gluteus medius peak amplitude (0.9 mV, P = 0.043) were observed after ground contact in the ‘with orthoses’ condition. With the addition of orthoses, a more pronated foot posture correlated with earlier vastus medialis oblique onset (r = − 0.51, P = 0.02) whilst higher Kujala scores correlated with earlier gluteus medius onset (r = 0.52, P = 0.02).
Interpretation: Although small in magnitude, reductions in hip adduction, knee internal rotation and gluteus medius amplitude observed immediately following orthoses application during a task that commonly aggravates symptoms, offer a potential mechanism for their effectiveness in patellofemoral pain management. Given the potential for cumulative effects of weight bearing repetitions completed with a foot orthoses, for example during repeated stair ascent, the differences are likely to be clinically meaningful.

Question 31

Outcome Predictors for Conservative Patellofemoral Pain Management: A Systematic Review and Meta-Analysis

Accepted Answer

August 2014
Background: Patellofemoral pain (PFP) is highly prevalent within both sporting and recreationally active populations. Multiple treatment approaches have been advocated for the management of PFP, attempting to address both intrinsic and extrinsic factors thought to contribute to the development and persistence of pain. A number of predictors of treatment success have been proposed, and evaluated, for directing intervention choice.Objective: Our aim was to systematically review the literature that identifies outcome predictors of specific conservative interventions in the management of PFP, including quality of the current evidence, to guide clinical practice and future studies investigating outcome predictors within this population.
Data Sources: The AMED, CINAHL, EMBASE, MEDLINE and Web of Science databases were searched from inception to April 2013.
Study Selection: Randomized controlled trials (RCTs) and cohort studies.
Study Appraisal and Synthesis Methods: Following initial searching, all potential papers were assessed by two independent reviewers for inclusion using a checklist developed from the inclusion criteria. Cited, and citing, references were also searched in Google Scholar, but unpublished work was not sought. Methodological quality was assessed using a previously designed quality assessment scale. Definitions for levels of evidence were guided by recommendations made by van Tulder et al.
Results: Fifteen low-quality (LQ) cohort studies were included. No RCTs were found. This systematic review identified the evaluation of 205 conservative management outcome predictor variables. Of this large number of variables that have been assessed, 19 (9 %) were found to significantly predict a successful outcome. Where two or more outcome predictors and success determinants were consistent between studies, data were pooled. Within these studies, the low number of participants per output variable, and absence of controls, is likely to compromise the validity of the predictor’s accuracy. Very limited evidence identified higher functional index questionnaire scores (mean 0.82, 95 % confidence interval [CI] 0.18–1.46), greater forefoot valgus (mean 0.67, 95 % CI 0.05–1.28) and greater rearfoot eversion magnitude peak (mean −0.93, 95 % CI −1.84 to −0.01) to significantly predict improved outcomes with orthoses interventions. Shorter symptom duration (p = 0.019), lower frequency of pain (p = 0.012), younger age, faster vastus medialis oblique reflex response time (p = 0.026), negative patella apprehension, absence of chondromalacia patella, tibial tubercle deviation of <14.6 mm and greater total quadriceps cross-sectional area on magnetic resonance imaging (p = 0.01), and reduced eccentric average quadriceps peak torque (p = 0.015) significantly predicted exercise intervention success following multivariate statistical analysis. Limited evidence identified increased Q-angle (mean 0.38, 95 % CI 0.05–0.72) and very limited evidence identified greater usual pain (mean 0.43, 95 % CI 0.01–0.85) to predict taping intervention success.
Conclusions: This systematic review provides a comprehensive summary of current derivation level studies identifying indicators of prediction for conservative PFP management. The overall strength of evidence was low. With appropriate caution, clinicians should consider taping for those with greater usual pain, orthoses for older individuals and exercise for younger individuals, and orthoses intervention for patients with greater forefoot valgus and rearfoot eversion magnitude peak. RCTs with evaluation of outcome prediction as a primary aim are clearly warranted to provide clinicians with robust evidence and facilitate evidence-informed, tailored intervention to this heterogeneous patient population.

Question 32

Patellar taping for patellofemoral pain: a systematic review and meta-analysis to evaluate clinical outcomes and biomechanical mechanisms

Accepted Answer

December 2013
Objective: Patellar taping is frequently used to treat patellofemoral pain (PFP). This systematic review and meta-analysis (1) evaluates the efficacy of patellar taping for patients with PFP, (2) compares the efficacy of various taping techniques and (3) identifies potential biomechanical mechanisms of action.
Methods: The MEDLINE, CINAHL, SPORTSDiscus, Web of Science and Google Scholar databases were searched in January 2013 for studies evaluating the effects of patellar taping on pain and lower-limb biomechanics in individuals with PFP. Three independent reviewers assessed each paper for inclusion and two assessed for quality. Means and SDs were extracted from each included study to allow effect size calculations.
Results: Twenty studies were identified. There is moderate evidence that (1) tailored (customised to the patient to control lateral tilt, glide and spin) and untailored patellar taping provides immediate pain reduction of large and small effect, respectively and (2) tailored patellar taping promotes earlier onset of vastus medialis oblique (VMO) contraction (relative to vastus lateralis contraction). There is limited evidence that (1) tailored patellar taping combined with exercise provides superior pain reduction compared to exercise alone at 4 weeks, (2) untailored patellar taping added to exercise at 3–12 months has no benefit and (3) tailored patellar taping promotes increased internal knee extension moments.
Conclusions: Tailoring patellar taping application (ie, to control lateral tilt, glide and spin) to optimise pain reduction is important for efficacy. Evaluation of tailored patellar taping beyond the immediate term is limited and should be a research priority. Possible mechanisms behind patellar taping efficacy include earlier VMO onset and improved knee function capacity (ie, ability to tolerate greater internal knee extension moments).

Question 33

Gluteal muscle activity and patellofemoral pain syndrome: a systematic review

Accepted Answer

August 2012
Objective: There is growing evidence to support the association of gluteal muscle strength deficits in individuals with patellofemoral pain syndrome (PFPS) and the effectiveness of gluteal strengthening when treating PFPS. In additiona, an impressive body of work evaluating gluteal electromyography (EMG) has recently emerged, further supporting the importance of gluteal muscle function in PFPS. This systematic review synthesises these EMG findings in order to better understand the role of gluteal muscle activity in the aetiology, presentation and management of PFPS.
Methods: MEDLINE, EMBASE, CINAHL, Web of Knowledge and Google Scholar databases were searched in September 2011 for prospective and case–control studies evaluating the association of gluteal EMG with PFPS. Two independent reviewers assessed each paper for inclusion and quality. Means and SDs were extracted from each included study to allow effect size calculations and comparison of results.
Results: Ten case–control, but no prospective studies were identified. Moderate-to-strong evidence indicates gluteus medius (GMed) activity is delayed and of shorter duration during stair negotiation in PFPS sufferers. In addition, limited evidence indicates GMed activity is delayed and of shorter duration during running, and gluteus maximus (GMax) activity is increased during stair descent.
Conclusions: Delayed and shorter duration of GMed EMG may indicate impaired ability to control frontal and transverse plane hip motion. Further research evaluating the value of gluteal muscle activity screening in identifying individuals most likely to develop PFPS, and the effectiveness of interventions targeting changes to gluteal muscle activation patterns is needed.

Question 34

The effect of anti-pronation foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in healthy individuals: A laboratory study

Accepted Answer

February 2014
Background: Greater frontal and transverse plane hip and knee motion, and delayed gluteus medius and vastus medialis oblique activation have frequently been identified in patellofemoral pain syndrome populations, whilst prefabricated anti-pronation foot orthoses have been reported to reduce symptoms. The aim of the study was to evaluate the effects of such orthoses on hip and knee kinematics, gluteal and vasti muscle activity, kinematic and electromyographic interactions alongside correlations with specific clinical measures.
Methods: Eighteen asymptomatic individuals (11 male 7 female) had measures taken of static foot posture and ankle range of motion. Hip muscle activity and kinematics were measured using electromyography and an active motion capture system during a step-up task. Order of testing with or without orthoses was determined using a coin toss.
Findings: Between condition paired t-tests indicated significantly reduced peak hip adduction angles (1.56°, P < 0.05) and significantly reduced knee internal rotation (1.3°, P < 0.05) in the orthoses condition. Reduced ankle dorsiflexion range of motion correlated with a reduction in hip adduction following the orthoses intervention (r = 0.59, P = 0.013).
Interpretation: The effects of prefabricated orthoses may be partially explained by kinematic alterations that occur proximal to the foot in the kinetic chain. These clinically and biomechanically relevant effects appear more evident in those with reduced underlying ankle motion. Further research is indicated using a symptomatic population to explore the clinical relevance of these observations.

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