Methods to assess patellofemoral joint stress: A systematic review

Acute effects of negative heel shoes on perceived pain and knee biomechanical characteristics of runners with patellofemoral pain

BACKGROUND

To determine the effects of negative heel shoes on perceived pain and knee biomechanical characteristics of runners with patellofemoral pain (PFP) during running.

METHODS

Sixteen runners with PFP ran in negative (-11 mm drops) and positive (5 mm drops) heel shoes while visual analog scale (VAS) scores, retroreflective markers, and ground reaction force were acquired by applying a 10-cm VAS, infrared motion capture system, and a three-dimensional force plate. Knee moment, patellofemoral joint stress (PFJS), and other biomechanical parameters during the stance phase were calculated based on inverse dynamics and a biomechanical model of the patellofemoral joint.

RESULTS

The foot inclination angle, peak PFJS during the stance phase, patellofemoral joint reaction force, knee extension moment, and quadriceps force at the time of peak PFJS of runners with PFP in negative heel shoes were lower than that in positive heel shoes, no significant difference was found in VAS scores, knee flexion angle, patellofemoral contact area, and quadriceps moment arm at the time of peak PFJS.

CONCLUSIONS

Compared to positive heel shoes, running in negative heel shoes decreases peak PFJS in runners with PFP, which may decrease patellofemoral joint loading, thus reducing the possibility of further development of PFP.

TRAIL REGISTRATION

Sports Science Experiment Ethics Committee of Beijing Sport University. 2023095H, April 18, 2023 (prospectively registered).

The non-invasive evaluation technique of patellofemoral joint stress: a systematic literature review

Introduction: Patellofemoral joint stress (PFJS) is an important parameter for understanding the mechanism of patellofemoral joint pain, preventing patellofemoral joint injury, and evaluating the therapeutic efficacy of PFP rehabilitation programs. The purpose of this systematic review was to identify and categorize the non-invasive technique to evaluate the PFJS. Methods: Literature searches were conducted from January 2000 to October 2022 in electronic databases, namely, PubMed, Web of Science, and EBSCO (Medline, SPORTDiscus). This review includes studies that evaluated the patellofemoral joint reaction force (PJRF) or PFJS, with participants including both healthy individuals and those with patellofemoral joint pain, as well as cadavers with no organic changes. The study design includes cross-sectional studies, case-control studies, and randomized controlled trials. The JBI quality appraisal criteria tool was used to assess the risk of bias in the included studies. Results: In total, 5016 articles were identified in the database research and the citation network, and 69 studies were included in the review. Discussion: Researchers are still working to improve the accuracy of evaluation for PFJS by using a personalized model and optimizing quadriceps muscle strength calculations. In theory, the evaluation method of combining advanced computational and biplane fluoroscopy techniques has high accuracy in evaluating PFJS. The method should be further developed to establish the "gold standard" for PFJS evaluation. In practical applications, selecting appropriate methods and approaches based on theoretical considerations and ecological validity is essential.

Cumulative patellofemoral force and stress are lower during faster running compared to slower running in recreational runners

Management strategies for patellofemoral pain often involve modifying running distance or speed. However, the optimal modification strategy to manage patellofemoral joint (PFJ) force and stress accumulated during running warrants further investigation. This study investigated the effect of running speed on peak and cumulative PFJ force and stress in recreational runners. Twenty recreational runners ran on an instrumented treadmill at four speeds (2.5-4.2 m/s). A musculoskeletal model derived peak and cumulative (per 1 km of continuous running) PFJ force and stress for each speed. Cumulative PFJ force and stress decreased with faster speeds (9.3-33.6% reduction for 3.1-4.2 m/s vs. 2.5 m/s). Peak PFJ force and stress significantly increased with faster speeds (9.3-35.6% increase for 3.1-4.2 m/s vs. 2.5 m/s). The largest cumulative PFJ kinetics reductions occurred when speeds increased from 2.5 to 3.1 m/s (13.7-14.2%). Running at faster speeds increases the magnitude of peak PFJ kinetics but conversely results in less accumulated force over a set distance. Selecting moderate running speeds (~3.1 m/s) with reduced training duration or an interval-based approach may be more effective for managing cumulative PFJ kinetics compared to running at slow speeds.

Relationship between kinesiophobia, isometric hip and knee torques to pelvic, hip and knee motion during the single-leg drop jump in women with patellofemoral pain: A cross-sectional study

BACKGROUND

Individuals with patellofemoral pain (PFP) have kinesiophobia and hip and knee strength deficits. These factors may be related to kinematic alterations of pelvic, hip and knee during a more demanding functional activity, such as jumping landing. The aim was to investigate the relationships between kinesiophobia and hip/knee torque to pelvic/hip/knee kinematics during the single-leg drop vertical jump in women with PFP.

METHOD

Thirty women with PFP were assessed with Tampa Scale for Kinesiophobia; isokinetic dynamometry of the hip extensor, hip abductor, and knee extensor; and three-dimensional motion analysis system during the single-leg drop vertical jump. A Pearson correlation matrix was used to investigate relationship among variables.

RESULTS

Fair correlations were found between increased kinesiophobia and increased peak hip internal rotation angle (r = 0.43; p = 0.018) as well as between greater peak knee extensor torque and greater peak knee flexion (r = 0.41; p = 0.022). Moderate to good correlation was found between increased peak hip abductor torque and increased peak contralateral pelvic drop (r = 0.52; p = 0.003). No other significant correlations were found between variables.

CONCLUSIONS

Kinesiophobia is associated with hip kinematics, but not with knee kinematics, during the single-leg vertical drop jump in women with PFP. The greater hip abductor torque is associated with greater contralateral pelvic drop. The positive relationship between knee extensor torque and knee flexion indicates that rehabilitation programs involving quadriceps muscle strengthening may assist women with PFP in control knee flexion and improve load absorption during jumping landing.

Do biomechanical foot-based interventions reduce patellofemoral joint loads in adults with and without patellofemoral pain or osteoarthritis? A systematic review and meta-analysis

OBJECTIVE

To evaluate the effects of biomechanical foot-based interventions (eg, footwear, insoles, taping and bracing on the foot) on patellofemoral loads during walking, running or walking and running combined in adults with and without patellofemoral pain or osteoarthritis.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

MEDLINE, CINAHL, SPORTdiscus, Embase and CENTRAL.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

English-language studies that assessed effects of biomechanical foot-based interventions on peak patellofemoral joint loads, quantified by patellofemoral joint pressure, reaction force or knee flexion moment during gait, in people with or without patellofemoral pain or osteoarthritis.

RESULTS

We identified 22 footwear and 11 insole studies (participant n=578). Pooled analyses indicated low-certainty evidence that minimalist footwear leads to a small reduction in peak patellofemoral joint loads compared with conventional footwear during running only (standardised mean difference (SMD) (95% CI) = -0.40 (-0.68 to -0.11)). Low-certainty evidence indicated that medial support insoles do not alter patellofemoral joint loads during walking (SMD (95% CI) = -0.08 (-0.42 to 0.27)) or running (SMD (95% CI) = 0.11 (-0.17 to 0.39)). Very low-certainty evidence indicated rocker-soled shoes have no effect on patellofemoral joint loads during walking and running combined (SMD (95% CI) = 0.37) (-0.06 to 0.79)).

CONCLUSION

Minimalist footwear may reduce peak patellofemoral joint loads slightly compared with conventional footwear during running only. Medial support insoles may not alter patellofemoral joint loads during walking or running and the evidence is very uncertain about the effect of rocker-soled shoes during walking and running combined. Clinicians aiming to reduce patellofemoral joint loads during running in people with patellofemoral pain or osteoarthritis may consider minimalist footwear.

Keep posting and following social media profiles about physical therapy, but be aware! A cross-sectional study of social media posts on Instagram and Twitter

BACKGROUND

Social media is established as a communication channel that is useful to disseminate scientific information. While social media can disseminate high quality information, it can also facilitate the spread of false or misleading information. Furthermore, social media is considered a self-promotion environment that can have several aspects related to personal marketing.

OBJECTIVE

To systematically search and review social media posts verifying whether the posts about physical therapy interventions reported sources of information; the presence of aspects suggesting conflicts of interest (COI); whether information was presented to facilitate knowledge acquisition; the reach of information posted; and the use and quality of the cited scientific references.

METHODS

Searches were performed on Instagram and Twitter using #reabilitação for Portuguese posts, and #rehabilitation for English posts. The inclusion criteria were posts including terms related to physical therapy and presenting interventions along with their purposes. The searches and screening processes were performed by at least two independent researchers.

RESULTS

Of 1,145 pre-selected posts, 632 posts were included, of which 14% cited references as source of information, 57% presented potential COI, and 9% facilitated knowledge acquisition. The posts received the mean ± SD of 88 ± 593 likes and profiles had a mean of 5,162 ± 37,240 followers. Considering the posts that cited references, most posts presented consistent information (51%) and 6% presented only positives outcomes (selection bias). Many references were of poor methodological quality (39%).

CONCLUSION

The present study enlightens the fact that most posts on Instagram and Twitter regarding physical therapy interventions did not report or use sources to support the information disseminated. Also, most posts were not created to facilitate knowledge acquisition.

REGISTRATION NUMBER

PROSPERO register database (CRD42021276941).

The effect of biomechanical foot-based interventions on patellofemoral joint loads during gait in adults with and without patellofemoral pain or osteoarthritis: a systematic review protocol

BACKGROUND

Patellofemoral pain is highly prevalent across the lifespan, and a significant proportion of people report unfavourable outcomes years after diagnosis. Previous research has implicated patellofemoral joint loading during gait in patellofemoral pain and its sequelae, patellofemoral osteoarthritis. Biomechanical foot-based interventions (e.g., footwear, insoles, orthotics, taping or bracing) can alter patellofemoral joint loads by reducing motions at the foot that increase compression between the patella and underlying femur via coupling mechanisms, making them a promising treatment option. This systematic review will summarise the evidence about the effect of biomechanical foot-based interventions on patellofemoral joint loads during gait in adults with and without patellofemoral pain and osteoarthritis.

METHODS

MEDLINE (Ovid), the Cumulative Index to Nursing and Allied Health Literature CINAHL, The Cochrane Central Register of Controlled Trials (CENTRAL), SPORTdiscus (EBSCO) and Embase (Ovid) will be searched. Our search strategy will include terms related to 'patellofemoral joint', 'loads' and 'biomechanical foot-based interventions'. We will include studies published in the English language that assess the effect of biomechanical foot-based interventions on patellofemoral joint loads, quantified by patellofemoral joint pressure, patellofemoral joint reaction force and/or knee flexion moment. Two reviewers will independently screen titles and abstracts, complete full-text reviews, and extract data from included studies. Two reviewers will assess study quality using the Revised Cochrane Risk of Bias (RoB 2) tool or the Cochrane Risk Of Bias In Non-Randomized Studies - of Interventions (ROBINS-I) tool. We will provide a synthesis of the included studies' characteristics and results. If three or more studies are sufficiently similar in population and intervention, we will pool the data to conduct a meta-analysis and report findings as standardised mean differences with 95% confidence intervals. If a meta-analysis cannot be performed, we will conduct a narrative synthesis of the results and produce forest plots for individual studies.

DISCUSSION

This protocol outlines the methods of a systematic review that will determine the effect of biomechanical foot-based interventions on patellofemoral joint loads. Our findings will inform clinical practice by identifying biomechanical foot-based interventions that reduce or increase patellofemoral joint loads, which may aid the treatment of adults with patellofemoral pain and osteoarthritis.

TRIAL REGISTRATION

Registered with PROSPERO on the 4th of May 2022 (CRD42022315207).

Is Postural Control Affected in People with Patellofemoral Pain and Should it be Part of Rehabilitation? A Systematic Review with Meta-analysis

BACKGROUND

Growing evidence supports that exercise therapy is effective for patellofemoral pain (PFP) rehabilitation. Nevertheless, the improvements have been reported not to be sustained in the long term, suggesting that the current protocols may not comprehend all required functional factors to provide a consistent recovery. A potential neglected factor in treatment protocols for PFP is postural control. However, it is unclear whether this population presents balance impairments or the influence of postural control on pain and function during rehabilitation programmes.

OBJECTIVE

To investigate whether (Q1) balance is impaired in people with PFP compared to controls, (Q2) conservative interventions are effective to improve balance in people with PFP, and (Q3) balance exercises are effective to improve pain and function in people with PFP.

DATA SOURCES

Medline, Embase, CINAHL, SPORTDiscus, Web of Science and Cochrane Library, supplemented by hand searching of reference lists, citations and relevant systematic reviews in the field.

METHODS

A systematic review with meta-analysis was conducted according to the Cochrane recommendations and reported according to the PRISMA statement recommendations. We included cross-sectional studies comparing balance between people with and without PFP; and randomised controlled trials verifying the effect of conservative intervention on balance and the effect of balance intervention on pain and function in people with PFP. The risk of bias was assessed using the Epidemiological Appraisal Instrument for cross-sectional studies and the Physiotherapy Evidence Database scale for randomised controlled trials.

RESULTS

From 15,436 records, 57 studies (Q1 = 28, Q2 = 23, Q3 = 14) met the eligibility criteria. Meta-analyses indicated that people with PFP have worse anteroposterior (very low grade evidence, standardised mean difference [SMD] = 1.03, 95% CI 0.40-1.66) and mediolateral (moderate grade evidence, SMD = 0.87, 95% CI 0.31-1.42) balance compared to controls. Moderate grade evidence indicated that overall balance is not affected in people with PFP (SMD = 0.38, 95% CI - 0.05-0.82). Low to very low grade evidence indicates that interventions are ineffective for mediolateral (SMD = 0.01, 95% CI - 0.51-0.53) and overall (SMD = 0.49, 95% CI - 0.14-1.11) balance improvements, and low grade evidence indicates that interventions are effective to improve anteroposterior balance (SMD = 0.64, 95% CI 0.04-1.23). Moderate to low grade evidence indicated that balance interventions are effective to reduce pain (SMD = 0.82, 95% CI 0.26-1.38) and improve function (SMD = 0.44, 95% CI 0.09-0.80) when measured using questionnaires; and very low grade evidence indicated no efficacy for function measured via functional tests (SMD = 0.73, 95% CI - 0.16-1.61).

CONCLUSION

People with PFP likely present balance deficits compared to asymptomatic people. There was insufficient evidence to support the efficacy of interventions to improve or modify balance in people with PFP. Also, there was insufficient evidence to support the efficacy of balance exercises to improve pain and function in people with PFP. Trial Registration The present systematic review was registered in PROSPERO (CRD42018091717).

The effect of heel-to-toe drop of running shoes on patellofemoral joint stress during running

BACKGROUND

Traditional running shoes with heel-to-toe drops is thought to be a contributor to increased patellofemoral joint stress, which is proposed as a mechanism of patellofemoral pain.

RESEARCH QUESTION

Is there an increase in patellofemoral joint stress when running in shoes with drops compared to running in shoes without a drop?

METHODS

Lower limbs kinematics and ground reaction force were collected from eighteen healthy runners during over-ground running in shoes with 15 mm, 10 mm, 5 mm drops, and without a drop. Patellofemoral joint force and stress were calculated from the kinematic and kinetic data using a biomechanical model of the patellofemoral joint.

RESULTS

The peak patellofemoral joint stress was increased by more than 15% when running in shoes with 15 mm and 10 mm drops compared to running in shoes without a drop (p = 0.003, p = 0.001). The knee flexion angle was significantly increased when running in shoes with 15 mm, 10 mm and 5 mm drops (p = 0.014, p = 0.003, p = 0.002), the knee extension moment (p = 0.009, p = 0.002) and patellofemoral joint force (p = 0.003, p = 0.001) were increased when running in shoes with 15 mm and 10 mm drops, compared to running in shoes without a drop.

SIGNIFICANCE

Compared to running in shoes without a drop, running in shoes with drops > 5 mm increase the peak patellofemoral joint stress significantly, which is mainly due to the increased knee extension moment.

May the force be with you: understanding how patellofemoral joint reaction force compares across different activities and physical interventions-a systematic review and meta-analysis

OBJECTIVE

To systematically review and synthesise patellofemoral joint reaction force (PFJRF) in healthy individuals and those with patellofemoral pain and osteoarthritis (OA), during everyday activities, therapeutic exercises and with physical interventions (eg, foot orthotics, footwear, taping, bracing).

DESIGN

A systematic review with meta-analysis.

DATA SOURCES

Medline, Embase, Scopus, CINAHL, SportDiscus and Cochrane Library databases were searched.

ELIGIBILITY CRITERIA

Observational and interventional studies reporting PFJRF during everyday activities, therapeutic exercises, and physical interventions.

RESULTS

In healthy individuals, the weighted average of mean (±SD) peak PFJRF for everyday activities were: walking 0.9±0.4 body weight (BW), stair ascent 3.2±0.7 BW, stair descent 2.8±0.5 BW and running 5.2±1.2 BW. In those with patellofemoral pain, peak PFJRF were: walking 0.8±0.2 BW, stair ascent 2.5±0.5 BW, stair descent 2.6±0.5 BW, running 4.1±0.9 BW. Only single studies reported peak PFJRF during everyday activities in individuals with patellofemoral OA/articular cartilage defects (walking 1.3±0.5 BW, stair ascent 1.6±0.4 BW, stair descent 1.0±0.5 BW). The PFJRF was reported for many different exercises and physical interventions; however, considerable variability precluded any pooled estimates.

SUMMARY

Everyday activities and exercises involving larger knee flexion (eg, squatting) expose the patellofemoral joint to higher PFJRF than those involving smaller knee flexion (eg, walking). There were no discernable differences in peak PFJRF during everyday activities between healthy individuals and those with patellofemoral pain/OA. The information on PFJRF may be used to select appropriate variations of exercises and physical interventions.

The mechanical influence of bone spicules in the osteochondral junction: A finite element modelling study

While much has been done to study how cartilage responds to mechanical loading, as well as modelling such responses, arguably less has been accomplished around the mechanics of the cartilage-bone junction. Previously, it has been reported that the presence of bony spicules invading the zone of calcified cartilage, preceded the formation of new subchondral bone and the advancing of the cement line (Thambyah and Broom in Osteoarthr Cartil 17:456-463, 2009). In this study, the morphology and frequency of bone spicules in the cartilage-bone interface of osteochondral beams subjected to three-point bending were modelled, and the results are discussed within the context of biomechanical theories on bone formation. It was found that the stress and strain magnitudes, and their distribution were sensitive to the presence and number of spicules. Spicule numbers and shape were shown to affect the strain energy density (SED) distribution in the areas of the cement line adjacent to spicules. Stresses, strains and SED analyses thus provided evidence that the mechanical environment with the addition of spicules promotes bone formation in the cartilage-bone junction.

Acute Effects of Hip Mobilization With Movement Technique on Pain and Biomechanics in Females With Patellofemoral Pain: A Randomized, Placebo-Controlled Trial

CONTEXT

People with patellofemoral pain (PFP) present altered lower-limb movements during some activities. Perhaps, joint misalignment in the hip is one of the reasons for altered movement patterns in people with PFP. Some mobilization techniques have been designed to address joint misalignments.

OBJECTIVE

To investigate the acute effects of hip mobilization with movement (MWM) technique on pain and biomechanics during squats and jumps in females with and without PFP.

DESIGN

Randomized, placebo-controlled trial.

SETTING

Movement analysis laboratory.

PATIENTS

Fifty-six physically active females (28 with PFP and 28 asymptomatic) were divided into 4 groups: experimental group with PFP, sham group with PFP, experimental group without PFP, and sham group without PFP.

INTERVENTION(S)

The experimental groups received MWM for the hip, and the sham groups received sham mobilization.

MAIN OUTCOME MEASURES

Pain, trunk, and lower-limb kinematics, and hip and knee kinetics during single-leg squats and landings.

RESULTS

After the interventions, no difference between groups was found for pain. The PFP experimental group decreased hip internal rotation during squats compared with the PFP sham group (P = .03). There was no other significant difference between PFP groups for kinematic or kinetic outcomes during squats, as well as for any outcome during landings. There was no difference between asymptomatic groups for any of the outcomes in any of the tasks.

CONCLUSIONS

Hip mobilization was ineffective to reduce pain in people with PFP. Hip MWM may contribute to dynamic lower-limb realignment in females with PFP by decreasing hip internal rotation during squats. Therefore, hip MWM could be potentially useful as a complementary intervention for patients with PFP.

Verbal Instruction Reduces Patellofemoral Joint Loading During Bodyweight Squatting

Context: The bodyweight squat exercise is a common component for treatment and prevention of patellofemoral pain; however, it can also place a high load on the patellofemoral joint. Restricting anterior motion of the knees relative to the toes during squatting appears to reduce patellofemoral loading. However, exercise professionals typically rely on verbal instructions to alter squat technique. Objective: To evaluate the influence of verbal instructions regarding squat technique on patellofemoral joint loading. Design: Cross-sectional study. Setting: Motion analysis laboratory. Participants: Eleven uninjured females. Intervention: Participants performed bodyweight squats before (baseline) and after receiving verbal instructions to limit anterior knee motion. Two different types of verbal instruction were used, one intended to promote an internal focus of attention and the other intended to promote an external focus of attention. Three-dimensional kinematics and kinetics were recorded using a multicamera system and force plate. Main Outcome Measures: Sagittal plane patellofemoral joint forces and stress were estimated using a musculoskeletal model. Results: Participants demonstrated a reduction in patellofemoral joint forces (35.4 vs 31.3 N/kg; P = .01) and stress (10.7 vs 9.2 mPa; P = .002) after receiving instructions promoting an internal focus of attention, compared with their baseline trials. Participants also demonstrated a reduction in patellofemoral joint forces (35.4 vs 32.3 N/kg; P = .03) and stress (10.7 vs 9.6 mPa; P = .04) after receiving instructions promoting an external focus of attention (vs baseline). However, there were no significant differences in patellofemoral forces (P = .84) or stress (P = .41) for trials performed with an internal versus external attentional focus. Conclusion: It appears that verbal instruction regarding knee position influences patellofemoral joint loading during squatting.

Patellofemoral joint stress measured across three different running techniques

BACKGROUND

Patellofemoral pain (PFP) is the most common running-related injury. It has been shown in previous studies that gait retraining may have a beneficial effect on patellofemoral joint stress (PFJS).

RESEARCH QUESTION

Is there a reduction of PFJS across 4 running conditions: 1. runner's typical rearfoot strike pattern, 2. forefoot landing, 3. step rate increase by 10% and 4. forward trunk lean?

METHODS

Nineteen healthy runners (28.05 ± 5.03 years; 26.58 ± 8.85 km/week, 6.00 ± 4.51 years of running experience) completed one running trial for each condition, at the same subject-specific comfortable speed on a treadmill. Kinetic and kinematic data were collected and measures of hip, knee and ankle joint moments and PFJS were calculated.

RESULTS

Compared to rearfoot strike condition, peak PFJS and PFJS-time integral per step were significantly (P < 0.01) lower during forefoot landing and step rate increase conditions. PFJS per kilometer was significantly reduced for forefoot landing (17.01%; P < 0.01) and increased step rate (12.90%; P = 0.003). Forward trunk lean technique showed no significant differences in peak PFJS (P = 0.187), PFJS-time integral per step (P = 0.815) and PFJS per kilometer (P = 0.077) compared to rearfoot strike pattern.

INTERPRETATION

The comparison between techniques revealed greater reductions on PFJS by forefoot landing, followed by 10% step rate increase condition. These changes were the result of different lower limb movement strategies across the 2 running conditions. We conclude that compared to a rearfoot strike pattern, both a forefoot landing and step rate increase result in lower cumulative PFJS joint stress in healthy runners, with the forefoot landing being the most effective. These running technique modifications could be recommended to reduce PFJS loads and may have implications for PFP prevention.

Is there a correlation in frontal plane knee kinematics between running and performing a single leg squat in runners with patellofemoral pain syndrome and asymptomatic runners?

BACKGROUND

Knee kinematics when running, specifically knee valgus, have been linked to patellofemoral pain syndrome. Assessing running biomechanics requires skill, equipment and time. Clinically, the single leg squat is used to make inferences about knee kinematics during running. No evidence supports this practice.

METHODS

Sixteen asymptomatic runners and sixteen runners with patellofemoral pain syndrome were recruited. Asymptomatic runners were sub-divided by dominant and non-dominant leg and runners with patellofemoral pain syndrome by painful and non-painful leg. This gave four groups. Participants were videoed performing single leg squats and running on a treadmill. Frontal plane knee kinematics were calculated using the frontal plane projection angle. Correlation in frontal plane projection angle between running and single leg squat were calculated using Pearson's correlation coefficient. Differences in frontal plane projection angle between groups for running and single leg squat were calculated using multiple independent t-tests with Bonferroni correction.

FINDINGS

Correlation in frontal plane projection angle between running and the single leg squat was not statistically significant for the painful leg group (p = 0.19) but was for the remaining groups (p < 0.05). There was no statistically significant difference in frontal plane projection angle between the four groups when running. Single leg squat frontal plane projection angle was significantly larger for the painful leg group (10.3°) than the dominant leg (-0.2° (p = 0.003)) and non-dominant leg (-0.4° (p = 0.004)) in the asymptomatic runners group.

INTERPRETATION

The single leg squat cannot be used to make inferences about frontal plane knee kinematics in running gait in patellofemoral pain syndrome sufferers.