Is hip strength a risk factor for patellofemoral pain? A systematic review and meta-analysis

Biomechanical and biological factors of sexual dimorphism in anterior knee pain: Current concepts

Female gender is one of the commonly mentioned risk factors for anterior knee pain (AKP), among a spectrum of other factors including anatomical, biomechanical, hormonal, behavioral and psychological elements contributing to its development. Despite the focus on individual risk factors, there's a notable gap in comprehending how gender influences and interacts with other risk factors. The objective of this review was to identify and emphasize the connections between these interactions, gender-related risk factors for AKP, and the potential mechanisms that explain their associations with other risk factors, aiming to aid in the creation of precise prevention and treatment approaches. Gender influences the majority of risk factors for AKP, including anatomical, biomechanical, hormonal, behavioral and psychological factors. Women have on average smaller patellae, higher patellofemoral cartilage stress and for AKP, disadvantageous trochlear morphology, ligament and muscle composition and unfavorable neuromuscular control pattern. In contrast, men show on average an increased ability to strengthen their hip external rotators, which are both protective against AKP. Particularly in kinetic and kinematic analysis, men have been shown to have a distinctly different risk factor profile than women. Sex hormones may also play a role in the risk of AKP, with estrogen potentially influencing ligamentous laxity, increasing midfoot loading and affecting neuromuscular control of the lower extremities and testosterone positively affecting muscle mass and strength. The higher incidence of AKP in women is likely due to a combination of slightly increased risk factors. Although all risk factors can be present in both men and women and the holistic evaluation of each individual's risk factor composition is imperative regardless of gender, knowing distinctive risk factors may help with focused evaluation, treatment and implementing preventive measures of AKP.

Analysis of lower limb muscle strength characteristics of amateur runners with patellofemoral pain: A cross-sectional study

To analyze the lower limb muscle strength characteristics of amateur runners with patellofemoral pain (PFP). Sixty amateur runners (30 in the knee pain group, 30 in the control group) underwent measurements of hip abduction strength, knee extension strength, and knee flexion strength. Additionally, the hamstring/quadriceps ratio and limb strength symmetry index were calculated for all participants. Statistical analyses were conducted using linear mixed models. The hip abduction and knee extensors strength of amateur runners with PFP was significantly lower than that of the control group. The hamstring/quadriceps ratio was significantly higher in the male knee pain group compared to the control group, while no significant difference was found between the female knee pain group and the control group. Furthermore, both the hip abduction strength symmetry index and knee extensors symmetry index were significantly lower in the knee pain group compared to the control group. Amateur runners with PFP exhibit distinct lower limb strength characteristics compared to non-knee pain runners. Additionally, differences in lower limb strength characteristics between male and female amateur runners with PFP were observed. These findings emphasize the importance of considering functional and gender differences in PFP rehabilitation training.

Concomitant Ipsilateral Knee Pain Is Associated With Worse Preoperative Functional Status and Short-Term Outcomes After Hip Arthroscopy in Patients With Femoroacetabular Impingement Syndrome

PURPOSE

(1) To determine the effect of concomitant ipsilateral knee pain (IKP) on short-term outcomes after hip arthroscopic treatment of femoroacetabular impingement syndrome (FAIS) and (2) to determine whether IKP would improve with surgery.

METHODS

Data between September 2021 and May 2022 were reviewed. Patients with a diagnosis of FAIS who underwent hip arthroscopy with a minimum of 1-year follow-up were included. The exclusion criteria were prior ipsilateral hip or knee surgery, hip Tönnis grade greater than 1, knee Kellgren-Lawrence grade greater than 2, hip conditions (avascular necrosis, Legg-Calvé-Perthes disease, pigmented villonodular synovitis, osteoid osteoma, synovial chondromatosis, and developmental dysplasia of the hip), and spine diseases. All patients underwent knee magnetic resonance imaging preoperatively. Preoperative and short-term (1-year) patient-reported outcomes were collected, consisting of the Hip Sports Activity Scale score, weekly sports participation, modified Harris Hip Score (mHHS), 12-component International Hip Outcome Tool (iHOT-12) score, and visual analog pain scale (VAS) scores for the hip and the ipsilateral knee. The percentages of patients achieving the minimal clinically important difference and patient acceptable symptom state (PASS) for the mHHS and iHOT-12 score were calculated. Multivariate regression analysis was performed to determine the effect of IKP severity on postoperative outcomes. Subgroup analysis was performed between patients with IKP alleviation and those without IKP alleviation.

RESULTS

Among the 107 patients included, 47 presented with preoperative IKP. Compared with patients without IKP, the IKP cohort had comparable knee structural abnormalities (all with P > .05). Still, the IKP cohort showed inferior preoperative values for the mHHS (P = .003), iHOT-12 score (P = .016), hip VAS score (P = .001), and weekly sports participation (P = .039). Postoperatively, the IKP cohort had a lower mHHS (P = .046), lower iHOT-12 score (P = .037), and lower hip VAS score (P = .003) and were less likely to achieve the PASS for the mHHS (P = .021) and iHOT-12 score (P = .049). Patients with higher knee VAS scores were less likely to achieve the PASS for the mHHS (odds ratio, 0.61; P = .023). Within the IKP group, the knee VAS score improved from 2.3 to 1.0 (P < .001). Patients with alleviated IKP showed superior postoperative iHOT-12 scores (P = .038) compared with patients with persistent IKP.

CONCLUSIONS

Concomitant IKP at baseline negatively affected preoperative status and short-term clinical outcomes after arthroscopic treatment of FAIS. Patients with IKP were less likely to meet clinical thresholds. Most patients achieved IKP alleviation postoperatively, which was associated with superior clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

No sign of weakness: a systematic review and meta-analysis of hip and calf muscle strength after anterior cruciate ligament injury

OBJECTIVE

We aimed to determine hip and lower-leg muscle strength in people after ACL injury compared with an uninjured control group (between people) and the uninjured contralateral limb (between limbs).

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

MEDLINE, EMBASE, CINAHL, Scopus, Cochrane CENTRAL and SportDiscus to 28 February 2023.

ELIGIBILITY CRITERIA

Primary ACL injury with mean age 18-40 years at time of injury. Studies had to measure hip and/or lower-leg muscle strength quantitatively (eg, dynamometer) and report muscle strength for the ACL-injured limb compared with: (i) an uninjured control group and/or (ii) the uninjured contralateral limb. Risk of bias was assessed according to Cochrane Collaboration domains.

RESULTS

Twenty-eight studies were included (n=23 measured strength ≤12 months post-ACL reconstruction). Most examined hip abduction (16 studies), hip extension (12 studies) and hip external rotation (7 studies) strength. We found no meaningful difference in muscle strength between people or between limbs for hip abduction, extension, internal rotation, flexion or ankle plantarflexion, dorsiflexion (estimates ranged from -9% to +9% of comparator). The only non-zero differences identified were in hip adduction (24% stronger on ACL limb (95% CI 8% to 42%)) and hip external rotation strength (12% deficit on ACL limb (95% CI 6% to 18%)) compared with uninjured controls at follow-ups >12 months, however both results stemmed from only two studies. Certainty of evidence was very low for all outcomes and comparisons, and drawn primarily from the first year post-ACL reconstruction.

CONCLUSION

Our results do not show widespread or substantial muscle weakness of the hip and lower-leg muscles after ACL injury, contrasting deficits of 10%-20% commonly reported for knee extensors and flexors. As it is unclear if deficits in hip and lower-leg muscle strength resolve with appropriate rehabilitation or no postinjury or postoperative weakness occurs, individualised assessment should guide training of hip and lower-leg strength following ACL injury.

PROSPERO REGISTRATION NUMBER

CRD42020216793.

Influence of running on femoroacetabular joint bone-to-bone distances

There is limited data quantifying the influence of running on hip cartilage mechanics. The goal of this investigation was to quantify changes in hip joint bone-to-bone distance in response to a 3-mile treadmill run. We acquired magnetic resonance (MR) images of the dominant hip of eight young, asymptomatic runners (five males, three females) before and immediately after they ran 3 miles at a self-selected pace on a level treadmill. The femoral heads and acetabula were semiautomatically segmented from the pre- and post-exercise MR images to generate three-dimensional models of each participant's hip that were used to compute changes in the bone-to-bone distances incurred by the running exercise. We observed a significant 3% decrease in bone-to-bone distance from 3.47 ± 0.20 to 3.36 ± 0.22 mm between the femoral head and acetabulum after a 3-mile treadmill run (mean ± 95% confidence interval; p = 0.03). These findings provide new baseline data describing how running impacts the hip joint in young, asymptomatic runners.

Effectiveness of Interventions Aimed at Changing Movement Patterns in People With Patellofemoral Pain: A Systematic Review With Network Meta-analysis

OBJECTIVE: To summarize the effectiveness of interventions for changing movement during weight-bearing functional tasks in people with patellofemoral pain (PFP). DESIGN: Systematic review with network meta-analysis (NMA). LITERATURE SEARCH: Medline, Embase, CINAHL, SPORTDiscus, and Cochrane Library were searched from inception up to May 2023. STUDY SELECTION CRITERIA: Randomized controlled trials involving people with PFP and nonsurgical, nonpharmacological interventions on task kinematics were included. DATA SYNTHESIS: NMA was conducted for frontal knee movement data, and pairwise meta-analysis was used to pool data when NMA was not possible. Reduced movements were those changes that indicated movements occurring with less amplitude. The GRADE approach was used to grade the certainty of the evidence. RESULTS: Thirty-seven trials were included (n = 1235 participants). Combining knee/hip exercises with internal feedback had the strongest effect on reducing frontal knee movements (standardized mean difference [SMD] from NMA = -2.66; GRADE: moderate evidence). On pairwise comparisons, the same combination of interventions reduced frontal hip movements (SMD = -0.47; GRADE: moderate evidence) and increased sagittal knee movements (SMD = 1.03; GRADE: moderate evidence), with no effects on sagittal hip movements (GRADE: very low evidence), compared to knee/hip exercises alone. There was no effect for single applications of braces on the frontal knee movement (GRADE: very low evidence) and taping on movements of the knee, hip, and ankle (GRADE: very low to low evidence) compared to no intervention. CONCLUSION: Knee/hip exercises combined with internal feedback techniques may change knee and hip movements in people with PFP. The combination of these interventions can reduce frontal knee and hip movements, and can increase sagittal knee movements. J Orthop Sports Phys Ther 2023;53(12):1-13. Epub 14 September 2023. doi:10.2519/jospt.2023.11956.

Adolescent and young adult hip and knee strength profiles relate to running gait biomechanics

OBJECTIVES

Compare and assess relationships between strength and running biomechanics among healthy adolescents and young adult males and females.

DESIGN

Retrospective cohort.

SETTING

Clinic.

PARTICIPANTS

802 healthy participants (570 F, 232 M; 16.6 ± 2.3 years).

MAIN OUTCOME MEASURES

Mass-normalized knee flexor and extensor strength, hip adductor and abductor strength, hamstrings-to-quadriceps (H:Q), and abductor-to-adductor (Abd:Add) ratios were obtained using hand-held dynamometry. Mass-normalized peak vertical ground reaction force (vGRF), %stance, cadence, and stride length were obtained using an instrumented treadmill. Multivariate analyses of variance were used to compare strength and biomechanics across ages and sexes. Linear regressions were used to assess the relationships between strength and biomechanics, accounting for speed, age, and sex. Independent t-tests were used to compare strength between strength ratio profiles.

RESULTS

Strength and running biomechanics significantly differed between sexes (p-range: <0.001-0.05) and age groups (p-range: <0.001-0.02). Strength and strength ratios were significantly associated with increased cadence (p-range:0.001-0.04) and stride lengths (p-range:0.004-0.03), and decreased vGRF (p < 0.001). Lower H:Q ratios had significantly lower strength measures (p < 0.001). Higher Abd:Add ratios had significantly increased abductor strength (p < 0.001).

CONCLUSIONS

Strength and running biomechanics differed by sexes and ages. Hip and knee strength and strength ratios were related to select spatiotemporal and kinetic biomechanical features.

Activation, strength, and resistance: Which variables predict the kinematics of women with and without patellofemoral pain?

INTRODUCTION

Investigating the possible relationship between neuromuscular changes and movement alterations could help to describe the mechanisms underlying patellofemoral pain (PFP).

OBJECTIVE

To investigate whether activation and muscle strength of the trunk and lower limb and muscle resistance of the trunk predict the knee frontal and trunk sagittal kinematics in women with and without PFP.

METHOD

Sixty women (PFP, n = 30; asymptomatic, n = 30) underwent the single-leg squat test to collect electromyographic and kinematic data. Activation of transversus abdominis/internal oblique, gluteus medius (GMed), and vastus medialis oblique (VMO); knee frontal and trunk sagittal angles were analyzed. Participants also underwent maximal isometric tests to determine lateral trunk, hip abductor, and knee extensor torques and performed a lateral trunk resistance test. Multiple regression was used to determine predictive models.

RESULTS

In the PFP group, knee frontal angle (R2 = 0.39, p = 0.001) was predicted by GMed activation (β = 0.23, p = 0.000) and hip abductor torque (β = 0.08, p = 0.022). No variable was able to predict trunk sagittal kinematics in this group. In the asymptomatics, knee frontal angle (R2 = 0.16, p = 0.029) was predicted by hip abductor torque (β = 0.07, p = 0.029), while trunk sagittal angle (R2 = 0.24, p = 0.024) was predicted by VMO activation (β = 0.12, p = 0.016).

CONCLUSION

Kinematics is predicted by the muscles acting in the respective planes, such that hip abductors capacities are related to the knee frontal alignment in both groups, and that of the VMO is related to the trunk sagittal alignment only in asymptomatic women.

Exploring overweight and obesity beyond body mass index: A body composition analysis in people with and without patellofemoral pain

BACKGROUND

We compared body mass index (BMI), body fat, and skeletal muscle mass between (1) a mixed-sex nonathletic cohort of people with patellofemoral pain (PFP) and pain-free people, and (2) a nonathletic cohort of people with PFP and pain-free people subgrouped by sex (i.e., men and women with PFP vs. pain-free men and women).

METHODS

This cross-sectional study included 114 people with PFP (71 women, 43 men) and 54 pain-free controls (32 women, 22 men). All participants attended a single testing session to assess body composition measures, which included BMI, percentage of body fat (%BFBioimpedance), and skeletal muscle mass (both assessed by bioelectrical impedance analysis), and percentage of body fat (%BFSkinfold) (assessed by skinfold caliper analysis). A one-way univariate analysis of covariance (age and physical activity levels as covariates) was used to compare body composition measures between groups (i.e., PFP vs. pain-free group; women with PFP vs. pain-free women; men with PFP vs. pain-free men).

RESULTS

Women with PFP presented significantly higher BMI, %BFBioimpedance, and %BFSkinfold, and lower skeletal muscle mass compared to pain-free women (p ≤ 0.04; effect size : ‒0.47 to 0.85). Men with PFP and men and women combined had no differences in BMI, %BFBioimpedance, %BFSkinfold, and skeletal muscle mass compared to their respective pain-free groups (p > 0.05).

CONCLUSION

Our findings indicate that BMI and body composition measures should be considered as part of the evaluation and management of people with PFP, especially in women, who have demonstrated higher BMI and body fat and lower skeletal muscle mass compared to pain-free controls. Future studies should not assess body composition measures in a mixed-sex population without distinguishing men participants from women participants.

Hip rotation muscle strength is implicated in the progression of early post-traumatic osteoarthritis: A longitudinal evaluation up to 5 years following ACL reconstruction

INTRODUCTION

Following ACL reconstruction (ACLR), deficits in hip muscle strength and relationships to future outcomes are unknown.

METHODS

111 participants one year after ACLR, completed hip external rotation (ER) and internal rotation (IR) strength assessment. At 1 (n = 111) and 5 (n = 74) years post-ACLR, participants completed a battery of functional, symptomatic (Knee Osteoarthritis Outcome Score (KOOS)) and structural assessments (radiography, magnetic resonance imaging (MRI)). Cartilage health of the patellofemoral and tibiofemoral compartments was assessed with the semiquantitative MRI Osteoarthritis Knee Score. Hip rotation strength was compared between-limbs, and relationships between hip strength at 1 year and functional, symptomatic and cartilage outcomes at 1 and 5 years were investigated with regression models.

RESULTS

The index (ACLR) limb had weaker hip ER (but not IR) strength compared to the contralateral side (standardised mean difference ER = -0.33 (95%CI -0.60, -0.07; IR = -0.11 (95%CI -0.37, 0.15). Greater hip ER and IR strength was associated with superior function at 1 and 5 years, and better KOOS-Patellofemoral symptoms at 5 years. Greater hip ER strength was associated with lower odds of worsening tibiofemoral cartilage lesions at 5 years (odds ratio 0.01, 95%CI 0.00, 0.41).

CONCLUSION

Hip rotation strength may play a role in worsening function, symptoms and cartilage health after ACLR.

Lower extremity muscle volume in females with patellofemoral pain and its relationships to hip and knee torque: A cross-sectional study

OBJECTIVES

Compare lower extremity muscle volume in females with patellofemoral pain (PFP) to a cohort of pain-free females and investigate the relationship between thigh and hip muscle volume and torque.

DESIGN

Cross-sectional.

PARTICIPANTS

Twenty-one females, 13 with PFP and 8 pain-free controls.

MAIN OUTCOME MEASURES

We quantified normalized lower extremity muscle volume (cm3/kg*m) via magnetic resonance imaging and isometric hip and thigh torque (Nm/kg) via a multimodal dynamometer.

RESULTS

Versus pain-free individuals, females with PFP had smaller muscle volume of the anterior hip (P < 0.019; d = 0.97-2.42), deep external rotators (P < 0.006; d = 1.0-3.93), hamstrings (P < 0.009; d = 1.09-2.12), rectus femoris (P < 0.001; d = 1.79), and vastus intermedius (P < 0.001; d = 1.88). There was no difference in muscle volume of the gluteus maximus (P = 0.311; d = 0.22), gluteus medius (P = 0.087; d = 0.87), vastus lateralis (P = 0.22; d = 0.39), and vastus medialis (P = 0.47; d = 0.04). Gluteus maximus volume was moderately correlated to hip abduction torque (r = 0.60; P = 0.03). Vasti muscles and semitendinosus volume were moderately correlated to knee extension (r = 0.57-0.69; P < 0.05) and flexion (r = 0.66; P = 0.01) torque, respectively.

CONCLUSION

Females with PFP present with lesser thigh and hip muscle volumes, with variability in volumetric profiles across participants. Lower extremity knee extension and hip abduction strength are moderately associated with the vasti and gluteus maximus muscle volume, respectively.

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

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.

Overweight and obesity in young adults with patellofemoral pain: Impact on functional capacity and strength

PURPOSE

This study aimed to (a) investigate the proportion of overweight/obesity in a cohort of young adults with patellofemoral pain (PFP) and (b) explore the association of body mass index (BMI), body fat, and lean mass with functional capacity and hip and knee strength in people with PFP.

METHODS

We included a mixed-sex sample of young adults (18-35 years old) with PFP (n = 100). Measurements for BMI, percentage of body fat, and lean mass (assessed by bioelectrical impedance) were obtained. Functional capacity was assessed by the Anterior Knee Pain Scale, plank test, and single-leg hop test. Strength of the knee extensors, knee flexors, and hip abductors was evaluated isometrically using an isokinetic dynamometer. The proportion of overweight/obesity was calculated based on BMI. The association between BMI, body fat, and lean mass and functional capacity and strength was investigated using partial correlations, followed by hierarchical regression analysis, adjusted for covariates (sex, bilateral pain, and current pain level).

RESULTS

A total of 38% of our cohort had their BMI categorized as overweight/obese. Higher BMI was associated with poor functional capacity (ΔR² = 0.06-0.12, p ≤ 0.001) and with knee flexion strength only (ΔR² = 0.04, p = 0.030). Higher body fat was associated with poor functional capacity (ΔR² = 0.05-0.15, p ≤ 0.015) and reduced strength (ΔR² = 0.15-0.23, p < 0.001). Lower lean mass was associated with poor functional capacity (ΔR² = 0.04-0.13, p ≤ 0.032) and reduced strength (ΔR² = 0.29- 0.31, p < 0.001).

CONCLUSION

BMI, body fat, and lean mass should be considered in the assessment and management of young people with PFP because it may be detrimental to function and strength.

Kinematic and Kinetic Gait Characteristics in People with Patellofemoral Pain: A Systematic Review and Meta-analysis

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.

TRIAL REGISTRATION

PROSPERO # CRD42019080241.

Comparison of Functional Outcomes between Supervised Rehabilitation and Telerehabilitation in Female Patients with Patellofemoral Pain Syndrome during the COVID-19 Pandemic

Patellofemoral pain syndrome (PFPS) is a common cause of anterior knee pain, and therapeutic exercises are recommended. During the COVID-19 pandemic, despite recommendations on the importance of telerehabilitation, insufficient studies have investigated functional outcomes between supervised rehabilitation and telerehabilitation in patients with PFPS. This study aimed to compare the muscle strength, muscle activation time, and patient-reported outcomes between supervised rehabilitation and telerehabilitation in female patients with PFPS. A total of 61 patients (supervised, n = 30; telerehabilitation, n = 31) participated. Muscle strength and activation time of the quadriceps and hamstrings were measured using an isokinetic device. Hip muscle strength was evaluated using a hand-held dynamometer. Patient-reported outcomes were measured using the visual analog scale (VAS) for pain, Kujala Anterior Knee Pain Scale (AKPS) for functional ability, and Tampa scale for kinesiophobia (TSK-11). No significant differences were found in muscle strength, muscle activation time, or patient-reported outcomes of the involved knees between the two groups (p > 0.05). In addition, the rate of change in all parameters did not significantly differ between the two groups (p > 0.05). Telerehabilitation, such as a home-exercise program supervised by physical therapists, may be as effective as supervised rehabilitation in improving functional outcomes in female patients with PFPS.

The effect of three types of exercises programs on the patella location in athletes with patellofemoral pain

BACKGROUND

The aim of this study was to compare the effect of exercises focusing on the proximal and distal joints to knee and knee local exercises on the Patellar location in athletes with patellofemoral pain (PFP).

METHODS

A randomized controlled, single-blinded trial was conducted. Thirty-five athletes with PFP were randomly divided into three groups; proximal (12), distal (11) and local (12). Q Angle was measured with goniometer, tilt and congruence angle were measured with digital radiology before and after the exercise programs. The exercises were performed three sessions of 70 min per week, for 8 weeks. Data were analyzed by mixed analysis of variance, post hoc test and dependent t-test.

RESULTS

In the pre-intervention, no significant difference was observed between the groups (P > 0.05). But in the post-intervention, Q angle, tilt angle, congruence angle and knee pain in the proximal group were significantly less than the distal and local groups (P < 0.01); while there were no significant differences between the distal and local groups (P > 0.05). Also, in the proximal group, there were significant differences between pre-intervention and post intervention in Q angle, tilt angle and congruence angle (P = 0.001), but no significant differences were observed in the distal and local groups (P > 0.05). Knee pain in all three groups showed significant differences between pre-intervention and post-intervention (P < 0.01).

CONCLUSIONS

The findings of the present study indicated further improvement in patellar location and knee pain in the proximal group. Accordingly, proximal group exercises can improve the pain and performance of athletes with PFP by patellar relocation to the normal position.

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).

Trunk Biomechanics in Individuals with Knee Disorders: A Systematic Review with Evidence Gap Map and Meta-analysis

BACKGROUND

The trunk is the foundation for transfer and dissipation of forces throughout the lower extremity kinetic chain. Individuals with knee disorders may employ trunk biomechanical adaptations to accommodate forces at the knee or compensate for muscle weakness. This systematic review aimed to synthesize the literature comparing trunk biomechanics between individuals with knee disorders and injury-free controls.

METHODS

Five databases were searched from inception to January 2022. Observational studies comparing trunk kinematics or kinetics during weight-bearing tasks (e.g., stair negotiation, walking, running, landings) between individuals with knee disorders and controls were included. Meta-analyses for each knee disorder were performed. Outcome-level certainty was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), and evidence gap maps were created.

RESULTS

A total of 81 studies investigating trunk biomechanics across six different knee disorders were included (i.e., knee osteoarthritis [OA], total knee arthroplasty [TKA], patellofemoral pain [PFP], patellar tendinopathy [PT], anterior cruciate ligament deficiency [ACLD], and anterior cruciate ligament reconstruction [ACLR]). Individuals with knee OA presented greater trunk flexion during squatting (SMD 0.88, 95% CI 0.58-1.18) and stepping tasks (SMD 0.56, 95% CI 0.13-.99); ipsilateral and contralateral trunk lean during walking (SMD 1.36; 95% CI 0.60-2.11) and sit-to-stand (SMD 1.49; 95% CI 0.90-2.08), respectively. Greater trunk flexion during landing tasks in individuals with PFP (SMD 0.56; 95% CI 0.01-1.12) or ACLR (SMD 0.48; 95% CI 0.21-.75) and greater ipsilateral trunk lean during single-leg squat in individuals with PFP (SMD 1.01; 95% CI 0.33-1.70) were also identified. No alterations in trunk kinematics of individuals with TKA were identified. Evidence gap maps outlined the lack of investigations for individuals with PT or ACLD, as well as for trunk kinetics across knee disorders.

CONCLUSION

Individuals with knee OA, PFP, or ACLR present with altered trunk kinematics in the sagittal and frontal planes. The findings of this review support the assessment of trunk biomechanics in these individuals in order to identify possible targets for rehabilitation and avoidance strategies.

TRIAL REGISTRATION

PROSPERO registration number: CRD42019129257.

Effect of Flat Running Shoes on Hip Kinematics in Male Recreational Runners

Patellofemoral joint pain and iliotibial band syndrome are very common running-related injuries. Excessive contralateral pelvic drop, hip adduction, and hip internal rotation have been suggested to be associated with the two injuries. The purpose of this repeated measures and the cross-sectional study was to investigate the effect of flat running shoes on these kinematic variables compared with that of conventional running shoes with a 10 mm drop. Eighteen male recreational runners were recruited to run in flat shoes and conventional shoes with a 10 mm drop, in random order. Impact force data and lower extremity kinematics were synchronously obtained using two Kistler force plates and eight motion infrared cameras, whereas differences in the impact force and hip kinematics were compared using statistical parametric mapping. Regarding hip kinematics, the hip flexion (p = 0.004) and adduction angles (p = 0.004) decreased significantly at 30-70% and 62-85% of the stance phase, respectively, while wearing flat running shoes; the contralateral pelvic drop angle (p = 0.001) decreased significantly at 31-75% of the stance phase while wearing flat running shoes. The knee internal rotation angle (p = 0.035) decreased significantly at 8-17% of the stance phase while wearing flat running shoes compared with conventional running shoes. Given that these kinematic variables are associated with patellofemoral joint pain and iliotibial band syndrome, flat running shoes may have potential benefits for the prevention or treatment of knee injuries.

The effect of hip abductor fatigue on knee kinematics and kinetics during normal gait

Objective

To investigate the effect of hip abductor fatigue on the kinematics and kinetics of the knee joint during walking in healthy people to provide a new approach for the prevention and treatment of knee-related injuries and diseases.

Methods

Twenty healthy participants, ten females, and ten males, with a mean age of 25.10 ± 1.2 years, were recruited. Isometric muscle strength testing equipment was used to measure the changes in muscle strength before and after fatigue, and the surface electromyography (SEMG) data during fatigue were recorded synchronously. The Vicon system and an AMTI© force platform were used to record the kinematic parameters and ground reaction force (GRF) of twenty participants walking at a self-selected speed before and after fatigue. Visual 3D software was used to calculate the angles and torques of the hip and knee joints.

Results

After fatigue, the muscle strength, median frequency (MF) and mean frequency (MNF) of participants decreased significantly (P < 0.001). The sagittal plane range of motion (ROM) of the knee (P < 0.0001) and hip joint (P < 0.01) on the fatigue side was significantly smaller than before fatigue. After fatigue, the first and second peaks of the external knee adduction moment (EKAM) in participants were greater than before fatigue (P < 0.0001), and the peak values of the knee abduction moment were also higher than those before fatigue (P < 0.05). On the horizontal plane, there is also a larger peak of internal moment during walking after fatigue (P < 0.01).

Conclusion

Hip abductor fatigue affects knee kinematics and kinetics during normal gait. Therefore, evaluating hip abductor strength and providing intensive training for patients with muscle weakness may be an important part of preventing knee-related injuries.

Biomechanical characteristics and muscle function in individuals with patellofemoral osteoarthritis: A systematic review of cross-sectional studies

BACKGROUND

Our objective was to investigate kinematic and kinetic characteristics and changes in muscle function in individuals with patellofemoral osteoarthritis compared to healthy individuals.

METHODS

Searches were performed of the Medline, Embase, Web of Science, The Cochrane Library, LILACS, and SciELO databases until May of 2022 for observational studies comparing individuals with patellofemoral osteoarthritis to a control group. The PRISMA guidelines and recommendations of the Cochrane Collaboration were followed. The GRADE approach was used to analyze and synthesize the level of evidence.

FINDINGS

Fourteen studies were included, involving a total of 594 participants (360 with patellofemoral osteoarthritis and 234 controls). The level of evidence for pelvis, hip adduction and knee abduction angles at 45° of knee flexion during the single-leg squat, and knee flexion angle during the task of walking was very low. Regarding muscle strength, the level of evidence for isometric strength of the hip abductors, extensors and external rotators, and concentric strength of the knee extensors and flexors was very low. It was not possible to synthesize any type of evidence for kinetic, electromyography, or muscle volume variables.

INTERPRETATION

The level of evidence was very low for all synthesized evidence for kinematic and muscle strength variables. However, individuals with patellofemoral osteoarthritis have lower isometric strength of the hip abductor muscles. Further studies with adequate adjustment for confounding factors, such as the non-inclusion of individuals with osteoarthritis in the tibiofemoral compartment concomitant to patellofemoral osteoarthritis, are needed to gain a better understanding of the clinical characteristics of patellofemoral osteoarthritis.

Is there a correlation between isometric muscle strength and the kinematics of the pelvis, hip and knee during functional tasks in women with patellofemoral pain?

OBJECTIVES

To evaluate the correlation between isometric muscle strength of the hip abductors (HABD) and lateral rotators (HLR) with the range of motion (ROM) of the pelvis/hip in the frontal/transverse planes, respectively, and between the strength of the knee extensors (KExt) with the ROM of the knee in the sagittal plane during seven tasks.

DESIGN

Cross-sectional study.

SETTING

Laboratory.

PARTICIPANTS

Thirty-five women with patellofemoral pain.

MAIN OUTCOME MEASURES

Maximum isometric muscle strength of the HABD, HLR, and KExt was measured using a manual dynamometer, and pelvis and lower limbs kinematics were evaluated using 3D optical system during gait, ascending and descending stairs, the forward and lateral step down tests, and the propulsion and landing phases of the single leg hop test (SLHT).

RESULTS

A weak correlation was found between KExt strength and knee ROM in the sagittal plane (p = 0.05; r = -0.33) during SLHT landing, and a moderate correlation between HABD strength and ROM of pelvic obliquity (p < 0.01; r = 0.50) during ascending stairs.

CONCLUSIONS

The lower strength of KExt has a weak correlation with higher knee flexion during the landing phase of the SLHT, and the lower strength of HABD has a moderate correlation with lower pelvis ROM in the frontal plane when ascending stairs.

Frontal plane biomechanics during single-leg squat and hip strength in patients with isolated patellofemoral osteoarthritis compared to matched controls: A cross-sectional study

The patellofemoral compartment of the knee is the most frequently affected by osteoarthritis. However, there is a lack of biomechanics studies on patellofemoral osteoarthritis (PFOA). This study’s purpose was to compare the frontal plane biomechanics of the trunk and lower limb during the single-leg squat and isometric hip abductor torque in individuals with isolated PFOA and controls. Frontal plane kinematics during the single-leg squat were evaluated using a three-dimensional (3-D) motion analysis system. Isometric hip abductor torque was determined using a handheld dynamometer. Twenty individuals participated in the study (10 with PFOA and 10 controls). No significant differences between groups were found regarding age (mean ± SD, PFOA group = 51.8 ± 6.9 versus control group = 47.8 ± 5.5; mean difference = 4, 95% confidence interval [CI] = -1.9 to 9.9, p = 0.20) or body mass index (PFOA group = 27.6 ± 2.2 versus control group = 25.5 ± 2.5; mean difference = 2.1, 95% confidence interval [CI] = -0.1 to 4.3, p = 0.06). Compared to control, the PFOA group presented greater hip adduction in the descending and ascending phases of the single-leg squat at 45° (mean difference [95% CI] = 6.44° [0.39–12.48°], p = 0.04; mean difference [95% CI] = 5.33° [0.24–10.42°], p = 0.045, respectively) and 60° (mean difference [95% CI] = 8.44° [2.15–14.73°], p = 0.01; mean difference [95% CI] = 7.58° [2.1–13.06°], p = 0.009, respectively) of knee flexion. No significant differences between groups were found for the frontal plane kinematics of the trunk, pelvis or knee (p > 0.05). The PFOA group exhibited lower isometric hip abductor torque (mean difference [95% CI] = -0.34 Nm/kg [-0.67 to -0.01 Nm/kg], p = 0.04). The individuals with PFOA presented greater hip adduction than the control group, which could increase lateral patellofemoral joint stress at 45° and 60° of knee flexion in the descending and ascending phases of the single-leg squat. These individuals also exhibited hip abductor weakness in comparison to healthy controls.

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

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.

Plank Times and Lower Extremity Overuse Injury in Collegiate Track-and-Field and Cross Country Athletes

Trunk muscle endurance has been theorized to play a role in running kinematics and lower extremity injury. However, the evidence examining the relationships between static trunk endurance tests, such as plank tests, and lower extremity injury in athletes is conflicting. The purpose of this study was to assess if collegiate cross country and track-and-field athletes with shorter pre-season prone and side plank hold times would have a higher incidence of lower extremity time-loss overuse injury during their competitive sport seasons. During the first week of their competitive season, 75 NCAA Division III uninjured collegiate cross country and track-and-field athletes (52% female; mean age 20.0 ± 1.3 years) performed three trunk endurance plank tests. Hold times for prone plank (PP), right-side plank (RSP) and left-side plank (LSP) were recorded in seconds. Athletes were followed prospectively during the season for lower extremity overuse injury that resulted in limited or missed practices or competitions. Among the athletes, 25 (33.3%) experienced a lower extremity overuse injury. There were no statistically significant mean differences or associations found between PP, RSP or LSP plank test hold times (seconds) and occurrence of lower extremity overuse injury. In isolation, plank hold times appear to have limited utility as a screening test in collegiate track-and-field and cross country athletes.

Confidence and Knowledge of Athletic Trainers in Managing Patellofemoral Pain

CONTEXT

Patellofemoral pain (PFP) is prevalent and challenging to manage. Most patients with PFP are unsatisfied with their knee function at 6 months after treatment and report ongoing pain up to 16 years after diagnosis. The confidence and knowledge of athletic trainers (ATs) in providing evidence-based care to people with PFP is unknown.

OBJECTIVE

To investigate the confidence and knowledge of ATs in the diagnosis, risk factors, prognosis, and treatment with current evidence for PFP.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENT OR OTHER PARTICIPANTS

A random sample of 3000 ATs were invited to participate; 261 completed the survey (10% participation rate, 88% completion rate).

MAIN OUTCOME MEASURES(S)

We surveyed AT demographics, confidence in PFP management, and knowledge related to diagnosis, risk factors, prognosis, and treatment. The confidence and knowledge of ATs in managing PFP was assessed. Their beliefs about evidence were compared with the available evidence (ie, consensus statements, position statements, systematic reviews).

RESULTS

Of the ATs surveyed, 91% were confident that their management of PFP aligned with the current evidence, but only 59% were confident in identifying risk factors for PFP development. In addition, 91% to 92% of ATs agreed that quadriceps and hip muscle weakness were risk factors for PFP, which aligns with the current evidence for the former but not the latter. Moreover, 93% to 97% of ATs' responses related to therapeutic exercise aligned with current evidence. However, 35% to 48% supported the use of passive treatments, such as electrophysical agents and ultrasound, which did not align with the current evidence.

CONCLUSIONS

Most ATs were aware of supporting evidence for therapeutic exercise in PFP management and were confident providing it, creating a strong foundation for evidence-based care. However, varying levels of awareness of the evidence related to risk factors and passive treatments for PFP highlight the need for professional development initiatives to better align ATs' knowledge with the current evidence.

Brain Activity During Experimental Knee Pain and Its Relationship With Kinesiophobia in Patients With Patellofemoral Pain: A Preliminary Functional Magnetic Resonance Imaging Investigation

Context: The etiology of patellofemoral pain has remained elusive, potentially due to an incomplete understanding of how pain, motor control, and kinesiophobia disrupt central nervous system functioning. Objective: To directly evaluate brain activity during experimental knee pain and its relationship to kinesiophobia in patients with patellofemoral pain. Design: Cross-sectional. Methods: Young females clinically diagnosed with patellofemoral pain (n = 14; 14.4 [3.3] y; body mass index = 22.4 [3.8]; height = 1.61 [0.1] m; body mass = 58.4 [12.7] kg). A modified Clarke test (experimental pain condition with noxious induction via patella pressure and quadriceps contraction) was administered to the nondominant knee (to minimize limb dominance confounds) of patients during brain functional magnetic resonance imaging (fMRI) acquisition. Patients also completed a quadriceps contraction without application of external pressure (control contraction). Kinesiophobia was measured using the Tampa Scale of Kinesiophobia. The fMRI analyses assessed brain activation during the modified Clarke test and control contraction and assessed relationships between task-induced brain activity and kinesiophobia. Standard processing for neuroimaging and appropriate cluster-wise statistical thresholds to determine significance were applied to the fMRI data (z > 3.1, P < .05). Results: The fMRI revealed widespread neural activation in the frontal, parietal, and occipital lobes, and cerebellum during the modified Clarke test (all zs > 4.4, all Ps < .04), whereas neural activation was localized primarily to frontal and cerebellar regions during the control contraction test (all zs > 4.4, all Ps < .01). Greater kinesiophobia was positively associated with greater activity in the cerebello-frontal network for the modified Clarke test (all zs > 5.0, all Ps < .01), but no relationships between kinesiophobia and brain activity were observed for the control contraction test (all zs < 3.1, all Ps > .05). Conclusions: Our novel experimental knee pain condition was associated with alterations in central nociceptive processing. These findings may provide novel complementary pathways for targeted restoration of patient function.

How Do Hip Exercises Improve Pain in Individuals With Patellofemoral Pain? Secondary Mediation Analysis of Strength and Psychological Factors as Mechanisms

OBJECTIVE

To determine whether the effect of hip exercise on patellofemoral pain is mediated through changes in hip muscle strength or psychological factors.

DESIGN

Secondary mediation analysis of a randomized clinical trial, in which 218 participants with patellofemoral pain were randomly assigned to receive foot orthoses or hip exercises.

METHODS

Pain (Knee injury and Osteoarthritis Outcome Score pain subscale) and number of pain-free squats at 12 weeks were the outcomes for this mediation analysis, as they are pathognomonic of patellofemoral pain. Hip strength dynamometry (abduction, adduction, and external rotation) and psychological characteristics (pain catastrophizing, kinesiophobia, and anxiety) measured at 6 weeks were considered as potential mediators. We used mediation analysis to decompose the total effect of treatment on the outcome into (1) the "indirect effect" (ie, the portion acting through the mediator) and (2) the "direct effect."

RESULTS

The effect of hip exercise on pain and squats was not mediated by any of the strength or psychological mediators analyzed. All indirect effects were small and showed wide 95% confidence intervals (CIs) that contained zero (eg, for pain-free squats: abduction strength, -0.13; 95% CI: -0.49, 0.23; Tampa Scale of Kinesiophobia, -0.17; 95% CI: -0.64, 0.30).

CONCLUSION

Hip strength improved after hip exercise, yet strength did not mediate improvements in pain and pain-free squats, and alternative psychological mediators were not implicated. J Orthop Sports Phys Ther 2021;51(12):602-610. doi:10.2519/jospt.2021.10674.

Adding muscle power exercises to a strength training program for people with patellofemoral pain: protocol of a randomized controlled trial

Background

Strong evidence supports the proximal combined with quadriceps strengthening for patellofemoral pain (PFP) rehabilitation. However, most reported rehabilitation programs do not follow specific exercise prescription recommendations or do not provide adequate details for replication in clinical practice. Furthermore, people with PFP have power deficits in hip and knee muscles and it remains unknown whether the addition of power exercises would result in superior or more consistent outcomes. Therefore, this study is designed to verify whether the benefits of a rehabilitation program addressing proximal and knee muscles comprising power and strength exercises are greater than those of a program consisting of strength exercises only.

Method

This study will be a randomized controlled trial that will be conducted at university facilities. A minimum of 74 people with PFP between the ages of 18 and 45 years will be included. The experimental group will engage in a 12-week resistance training program focusing on proximal and knee muscles using power and strength exercises. The control group will engage in a 12-week resistance training program focusing on proximal and knee muscles using strength exercises only. Primary outcomes will be pain intensity and physical function; and secondary outcomes will be kinesiophobia, self-reported improvement, quality of life, peak hip and knee torque, and hip and knee rate of force development. The primary outcomes will be evaluated at baseline, and after 6 weeks, 12 weeks, 3 months, 6 months, and 1 year. The secondary outcomes will be evaluated at baseline and immediately after the interventions. Therapists and participants will not be blinded to group allocation.

Discussion

This randomized clinical trial will investigate if adding power exercises to a progressive resistance training may lead to more consistent outcomes for PFP rehabilitation. The study will provide additional knowledge to support rehabilitation programs for people with PFP.

Trial registration

ClinicalTrials.gov NCT 03985254. Registered on 26 August 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05748-x.

Knee and Hip Isometric Force Steadiness Are Impaired in Women With Patellofemoral Pain

ABSTRACT

Ferreira, AS, de Oliveira Silva, D, Ferrari, D, Magalhães, FH, Pappas, E, Briani, RV, Pazzinatto, MF, and de Azevedo, FM. Knee and hip isometric force steadiness are impaired in women with patellofemoral pain. J Strength Cond Res 35(10): 2878-2885, 2021-The purposes were as follows: to compare knee extension and hip abduction force steadiness and maximal strength between women with patellofemoral pain (PFP) and pain-free women; and to investigate whether maximal strength, self-reported pain during force-matching tasks, self-reported knee function, symptoms duration, and physical activity level are associated with knee extension and hip abduction force steadiness. Thirty women with PFP and 30 pain-free women were recruited. Knee extension and hip abduction maximal voluntary isometric contractions and submaximal isometric force-matching tasks were evaluated using an isokinetic dynamometer. Subjects were asked to match a target force corresponding to 10% of their maximal isometric voluntary contraction while force steadiness was computed as the coefficient of variation (CV) of the exerted force. Women with PFP had significant 36% lower knee extension and 33% lower hip abduction peak strength. They also had significant 70% lower knee extension force steadiness and 60% lower hip abduction force steadiness (i.e., higher CV) than pain-free women. Self-reported pain and self-reported knee function were significantly associated (r = 0.61, p < 0.001; r = -0.35, p = 0.05) and able to predict 41% of the variance of knee extensor force steadiness. Hip abductor maximum strength was significantly associated (r = -0.57; p = 0.001) and able to predict 32% of the variance of hip abductor force steadiness. These findings indicate that muscle impairments in PFP go beyond only low knee and hip muscle strength because women with PFP also present deficits in knee extension and hip abduction force steadiness. Evidence-based treatments aiming at improving force steadiness may be a promising addition to PFP rehabilitation programs.

Impaired Isometric, Concentric, and Eccentric Rate of Torque Development at the Hip and Knee in Patellofemoral Pain

ABSTRACT

Ferreira, AS, de Oliveira Silva, D, Barton, CJ, Briani, RV, Taborda, B, Pazzinatto, MF, and de Azevedo, FM. Impaired isometric, concentric, and eccentric rate of torque development at the hip and knee in patellofemoral pain. J Strength Cond Res 35(9): 2492-2497, 2021-The aims of this study were to compare maximal muscle strength and rate of torque development (RTD) of knee extensor and hip abductor during isometric, concentric, and eccentric contractions between women with and without patellofemoral pain (PFP). Thirty-eight women with PFP (PFPG) and 38 pain-free women (CG) participated in this study. Isometric, concentric, and eccentric maximal torque and RTD of knee extensor and hip abductor were assessed using an isokinetic dynamometer. Rate of torque development was calculated as the change in torque over the change in time from torque onset to 30, 60, and 90% of the maximal torque (RTD30%, RTD60%, and RTD90%) during isometric, concentric, and eccentric contractions. PFPG had lower isometric, concentric, and eccentric knee extensor maximal torque (29.9, 28.3, and 26.7%) compared with the CG. For knee extensor RTD, PFPG had slower isometric RTD30% (17.8%), RTD60% (21.5%), and RTD90% (23.4%); slower concentric RTD30% (35.7%), RTD60% (29.3%), and RTD90% (28.2%); and slower eccentric RTD30% (20.5%), RTD60% (25.2%), and RTD90% (22.5%) compared with the CG. PFPG had lower isometric, concentric, and eccentric hip abductor maximal torque (28.3, 21.8, and 17%) compared with the CG. For hip abductor RTD, PFPG had slower isometric RTD30% (32.6%), RTD60% (31.1%), and RTD90% (25.4%); slower concentric RTD90% (11.5%); and slower eccentric RTD30% (19.8%), RTD60% (26.4%), and RTD90% (24%) compared with the CG. In conclusion, women with PFP presented deficits in both maximal strength and RTD of knee extensor and hip abductor during isometric, concentric, and eccentric contractions, which highlight the potential importance of addressing different aspects of muscle function through exercise therapy.

Autoregulation in Resistance Training for Lower Limb Tendinopathy: A Potential Method for Addressing Individual Factors, Intervention Issues, and Inadequate Outcomes

Musculoskeletal disorders, such as tendinopathy, are placing an increasing burden on society and health systems. Tendinopathy accounts for up to 30% of musculoskeletal disorders, with a high incidence in athletes and the general population. Although resistance training has shown short-term effectiveness in the treatment of lower limb tendinopathy, more comprehensive exercise protocols and progression methods are required due to poor long-term outcomes. The most common resistance training protocols are predetermined and standardized, which presents significant limitations. Current standardized protocols do not adhere to scientific resistance training principles, consider individual factors, or take the importance of individualized training into account. Resistance training programs in case of tendinopathy are currently not achieving the required intensity and dosage, leading to high recurrence rates. Therefore, better methods for individualizing and progressing resistance training are required to improve outcomes. One potential method is autoregulation, which allows individuals to progress training at their own rate, taking individual factors into account. Despite the finding of their effectiveness in increasing the strength of healthy athletes, autoregulation methods have not been investigated in case of tendinopathy. The purpose of this narrative review was 3-fold: firstly, to give an overview and a critical analysis of the individual factors involved in tendinopathy and current resistance training protocols and their limitations. Secondly, to give an overview of the history, methods, and application of autoregulation strategies both in sports performance and physiotherapy. Finally, a theoretical adaptation of a current tendinopathy resistance training protocol using autoregulation methods is presented, providing an example of how the method could be implemented in clinical practice or future research.

How effective is an evidence-based exercise intervention in individuals with patellofemoral pain?

OBJECTIVES

Guidelines for a comprehensive rehabilitation programme for patellofemoral pain (PFP) have been developed by international experts. The aim of this study was to analyse the effect of such a rehabilitative exercise programme on pain, function, kinesiophobia, running biomechanics, quadriceps strength and quadriceps muscle inhibition in individuals with PFP.

DESIGN

Observational study.

SETTING

Clinical environment.

PARTICIPANTS

Twenty-seven participants with PFP.

MAIN OUTCOME MEASURES

Symptoms [numeric pain rating scale (NPRS)and the pain subscale of the Knee Injury and Osteoarthritis Outcome Score (KOOS)], function measured by using the KUJALA scale and KOOS, kinesiophobia measured by using the Tampa scale, three-dimensional biomechanical running data, quadriceps isometric, concentric and eccentric strength and arthrogenic muscle inhibition (AMI) were acquired before and after the six-week exercise programme.

RESULTS

Although pain did not significantly improve all patients were pain-free after the six-week exercise programme (NPRS: p = 0.074). Function, kinesiophobia and quadriceps AMI improved significantly after the six-week exercise programme (KUJALA: p = 0.001, KOOS: p = 0.0001, Tampa: p = 0.017, AMI: p = 0.018). Running biomechanics during stance phase did not change after the exercise intervention. Quadriceps strength was not different after the six-week exercise programme (isometric: p = 0.992, concentric: p = 0.075, eccentric: p = 0.351).

CONCLUSION

The results of this study demonstrate that the current exercise recommendations can improve function and kinesiophobia and reduce pain and AMI in individuals with PFP. There is a need for reconsideration of the current exercise guidelines in stronger individuals with PFP.

Motor Control Exercises Compared to Strengthening Exercises for Upper- and Lower-Extremity Musculoskeletal Disorders: A Systematic Review With Meta-Analyses of Randomized Controlled Trials

OBJECTIVE

The purpose of this review was to compare the efficacy of motor control exercises (MCEs) to strengthening exercises for adults with upper- or lower-extremity musculoskeletal disorders (MSKDs).

METHODS

Electronic searches were conducted up to April 2020 in Medline, Embase, Cochrane CENTRAL, and CINAHL. Randomized controlled trials were identified on the efficacy of MCEs compared to strengthening exercises for adults with upper- or lower-extremity MSKDs. Data were extracted with a standardized form that documented the study characteristics and results. For pain and disability outcomes, pooled mean differences (MDs) and standardized mean differences (SMDs) were calculated using random-effects inverse variance models.

RESULTS

Twenty-one randomized controlled trials (n = 1244 participants) were included. Based on moderate-quality evidence, MCEs lead to greater pain (MD = -0.41 out of 10 points; 95% CI = -0.72 to -0.10; n = 626) and disability reductions (SMD = -0.28; 95% CI = -0.43 to -0.13; n = 713) when compared to strengthening exercises in the short term; these differences are not clinically important. When excluding trials on osteoarthritis (OA) participants and evaluating only the trials involving participants with rotator cuff-related shoulder pain, shoulder instability, hip-related groin pain, or patellofemoral pain syndrome, there is moderate quality evidence that MCEs lead to greater pain (MD = -0.74 out of 10 points; 95% CI = -1.22 to -0.26; n = 293) and disability reductions (SMD = -0.40; 95% CI = -0.61 to -0.19; n = 354) than strengthening exercises in the short term; these differences might be clinically important.

CONCLUSIONS

MCEs lead to statistically greater pain and disability reductions when compared to strengthening exercises among adults with MSKDs in the short term, but these effects might be clinically important only in conditions that do not involve OA. Inclusion of new trials might modify these conclusions.

IMPACT

These results suggest that MCEs could be prioritized over strengthening exercises for adults with the included non-OA MSKDs; however, results are unclear for OA disorders.

Impaired muscle capacity of the hip and knee in individuals with isolated patellofemoral osteoarthritis: a cross-sectional study

AIMS

The aims of this study were to compare the capacity of the knee and hip muscles between individuals with and without isolated patellofemoral osteoarthritis (PFOA) and to evaluate the impact of PFOA on pain, stiffness, and physical function.

METHODS

This cross-sectional study evaluated muscle capacity of the hip and knee using an isokinetic dynamometer. The isokinetic variables used in the statistical analysis were peak torque, total work, and average power. Pain, stiffness, and physical function were assessed using questionnaires.

RESULTS

A total of 26 individuals participated in the study (13 with PFOA and 13 controls). The PFOA group exhibited lower peak torque, total work, and average power for knee extension and flexion in the concentric mode (p ⩽ 0.01) as well as lower peak torque and total work for knee extension (p ⩽ 0.005) and lower total work for knee flexion (p = 0.05) in the eccentric mode. The PFOA group exhibited lower peak torque of the extensor, abductor, adductor, and internal rotator muscles of the hip (p ⩽ 0.05), less total work of the abductor and adductor muscles (p ⩽ 0.04), and lower average power of eccentric adduction of the hip (p = 0.01) compared with the healthy controls. Compared with the control group, the PFOA group had a higher level of pain, stiffness, and compromised physical functioning self-reported (p ⩽ 0.005).

CONCLUSION

Participants with PFOA exhibited impairments regarding muscle capacity of the hip and knee, higher level of pain and stiffness as well as compromised physical functioning in comparison with healthy controls.

Effect of static knee joint flexion on vastus medialis obliquus fiber angle in patellofemoral pain syndrome: An ultrasonographic study

INTRODUCTION

In patients with patellofemoral pain syndrome, the vastus medialis obliquus muscle fiber angle measured by ultrasound at knee extension was found to be different from that in healthy individuals. An important feature of patellofemoral pain syndrome is the increase in pain severity during activities that require knee flexion.

OBJECTIVE

To investigate whether there was an ultrasonographic change in the vastus medialis obliquus fiber angle by flexing the knee joint in patients with patellofemoral pain syndrome compared to healthy pain-free individuals.

DESIGN

A cross-sectional clinical study.

SETTING

An outpatient clinic of a tertiary care hospital.

PARTICIPANTS

Forty-seven patients with patellofemoral pain syndrome (median age of 40 years) and 43 healthy volunteers (median age of 39 years) were included in the study.

INTERVENTIONS

No intervention.

MAIN OUTCOME MEASURES

Vastus medialis obliquus fiber angle measured by ultrasonography at three different positions of knee joint including extension, 30° of flexion, and 45° of flexion.

RESULTS

There was no significant change in the vastus medialis obliquus fiber angle with knee flexion in both groups (p > .05 for each group). However, the median vastus medialis obliquus fiber angle values in the group with patellofemoral pain syndrome were significantly lower at all knee joint angles than those in the comparison group (p < .05 at all knee joint angles).

CONCLUSIONS

Although the vastus medialis obliquus fiber angle does not change with static knee flexion, the lower angle of the vastus medialis obliquus fiber in those with patellofemoral pain syndrome implicitly suggests that vastus medialis obliquus dysfunction may exist.

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

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.

Anteromedial versus posterolateral hip musculature strengthening with dose-controlled in women with patellofemoral pain: A randomized controlled trial

OBJECTIVE

To compare the effectiveness of adding anteromedial versus posterolateral hip musculature strengthening to knee strengthening in women with patellofemoral pain (PFP).

DESIGN

Randomized controlled trial.

SETTING

University physiotherapy clinic.

PARTICIPANTS

Fifty-two women with PFP were randomized to receive either anteromedial (AMHG) or posterolateral (PLHG) hip musculature strengthening.

MAIN OUTCOME MEASURES

The primary outcomes were pain intensity by the numeric pain rating scale and function by the Anterior Knee Pain Scale in six weeks. Secondary outcomes were pain and function at six months, global perceived effect at six weeks and six months, pain in step down, isometric torque of abductors, adductors and hip rotators measured with hand-held dynamometer, and dynamic knee valgus by step down in six weeks.

RESULTS

Both groups showed improvement in primary outcomes; however, no differences were found between groups in pain intensity and function in six weeks and the secondary outcomes. Group x time interaction found superior gains in abductor strength in the PLHG and increase in the strength of the adductors and internal rotators in AMHG.

CONCLUSION

There was no difference between the addition of anteromedial or posterolateral hip musculature strengthening to knee strengthening in improving pain and function in women with PFP.

Normative measures of hip strength and relation to previous injury in collegiate cross-country runners

CONTEXT

Running related injury occurs frequently in collegiate cross-country runners. Hip strength is one factor that may be important in the rehabilitation and training of cross-country runners. However, no normative values exist to inform these strategies.

OBJECTIVE

Establish normative values for hip abduction and external rotation isometric strength in collegiate cross-country runners and explore the association between strength and previous injury.

DESIGN

Mixed methods using descriptive epidemiology and retrospective cross-sectional designs.

SETTING

University Laboratory Patients or Other Participants: Eighty-two NCAA Division III cross-country runners (38 males, 44 females) participated in this study.

MAIN OUTCOME MEASURE(S)

Isometric hip strength and reported injury Results: Males demonstrated greater absolute hip strength than females. Measures of hip strength were not different between sexes when normalized to height and mass. Hip abduction asymmetry was associated with previous injury in males. A combination of at least one leg with hip abduction weakness and bilateral external rotation weakness was associated with previous injury in females.

CONCLUSIONS

Knowledge of normative values of hip strength may help inform rehabilitation strategies in collegiate cross-country runners. Males and females may demonstrate differing strength profiles following running related injury.

Influence of symptom frequency and severity on hip abductor strength and endurance in individuals with patellofemoral pain

OBJECTIVE

To compare clinical measures of hip abductor strength and endurance of individuals with patellofemoral pain with more severe symptoms to those with less severe symptoms.

DESIGN

Cross-sectional.

SETTINGS

Laboratory.

PARTICIPANTS

Sixty participants with patellofemoral pain were divided three times into 2 groups according to three symptomatology criteria: functional capacity, pain frequency and pain severity.

MAIN OUTCOME MEASURES

Isometric strength evaluated using a hand-held dynamometer, endurance using maximum number of repetitions and maximum holding time, functional capacity using the Anterior Knee Pain Scale, pain frequency using a 2-category scale ("Less frequent" = 1-2 times a week; "More frequent" = >3 times a week) and pain severity using Numeric Pain Rating Scales.

RESULTS

Participants with more frequent symptoms and with more severe pain were significantly weaker (10%, p = 0.04 and 16%, p = 0.001, respectively), and had less isometric (17%, p = 0.02 and 24%, p = 0.002, respectively) and dynamic (13%, p = 0.02 and 23%, p = 0.007, respectively) endurance compared to those with less pronounced symptoms.

CONCLUSION

Our study highlighted that hip abductor strength and endurance deficits are more pronounced in individuals with more severe and frequent pain.

Osteoarthritic knees have a highly variable patellofemoral alignment: a systematic review

PURPOSE

This systematic review aimed to evaluate the variability of patellofemoral (PF) alignment and trochlear morphology in osteoarthritic knees.

METHODS

PF alignment of the knee was defined by the following parameters: the sulcus angle (SA), femoral trochlear depth (FTD), patellar tilt angle (PTA), lateral patellofemoral angle (LPFA), lateral femoral trochlear inclination (LFTI) and tibial tubercle-trochlear groove distance (TT-TG). The electronic databases MEDLINE and EMBASE were searched from database inception to the search date (February 19, 2019) and were screened for relevant studies. The PRISMA guidelines were followed. Articles reporting PF alignment measurements of osteoarthritic knees in patients over 40 years old were included. Data were extracted and methodological quality was assessed using a 14-item checklist.

RESULTS

A total of 8 studies met the inclusion criteria. The studies reported mean values ± SD between 120° and 141.1° ± 7.7 for the SA; 5.8 mm ± 1.4 for the FTD; between - 0.1° ± 3.3 and 10.3° ± 5.7 for the PTA; between 5.8° ± 5.4 and 17° for the LPFA; between 23.2° ± 5.0 and 27.1° ± 4.4 for the LFTI; and 5.8 mm ± 5.4 for the TT-TG.

CONCLUSION

PF alignment in the osteoarthritic knee is more variable than expected. This finding should encourage surgeons to consider the individual preoperative PF alignment more precisely with the aim of reducing anterior knee pain (AKP) after TKA. 3D-CT imaging might be of great value to analyse the PF alignment in an appropriate way.

LEVEL OF EVIDENCE

Level III.

Fatigue-Induced Hip-Abductor Weakness and Changes in Biomechanical Risk Factors for Running-Related Injuries

CONTEXT

Despite overlap between hip-abductor (HABD) weakness and fatigue-induced changes in running, the interaction of these theorized contributors to running injuries has been underevaluated.

OBJECTIVE

To assess the effects of a fatiguing run on HABD torque and evaluate the correlation between HABD torque and previously identified running-related injury pathomechanics while participants were rested or fatigued.

DESIGN

Crossover study.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 38 healthy, physically active males (age = 21.61 ± 4.02 years, height = 1.78 ± 0.08 m, body mass = 76.00 ± 12.39 kg).

INTERVENTION(S)

Data collection consisted of rested-state collection, a fatiguing treadmill-run protocol, and fatigued-state collection. For the HABD measures, side-lying handheld-dynamometer isometric tests were performed and converted to torque using femur length. For the gait analysis, kinematic (240 Hz) and kinetic (960 Hz) running (4.0 m/s) data were collected for 3 trials. The fatigue protocol involved a graded exercise test and 80% o2max run to exhaustion. Immediately after the run, fatigued-state measures were obtained.

MAIN OUTCOME MEASURE(S)

Variables of interest were HABD torque and peak angles, velocities, and moments for hip and knee adduction and internal rotation. Differences between conditions were compared using paired t tests. Pearson correlation coefficients were calculated to evaluate relationships between HABD torque and biomechanical variables.

RESULTS

Fatigue decreased HABD torque and increased hip-adduction angle, knee-adduction velocity, and hip and knee internal-rotation velocities and moments (all P values < .05). In the rested state, HABD torque was correlated with hip-adduction velocity (r = -0.322, P = .049). In the fatigued state, HABD torque was correlated with hip-adduction velocity (r = -0.393, P = .015), hip internal-rotation velocity (r = -0.410, P = .01), and knee-adduction angle (r = 0.385, P = .017) and velocity (r = -0.378, P = .019).

CONCLUSIONS

Changes in joint velocities due to fatigue and correlations between HABD torque and hip- and knee-joint velocities highlight the need to consider not only the quantity of HABD strength but also the rate of eccentric control of HABDs.

The Influence of Sagittal Plane Hip Position on Lower-Extremity Muscle Activity and Torque Output

CONTEXT

Hip muscle strength has previously been evaluated in various sagittal plane testing positions. Altering the testing position appears to have an influence on hip muscle torque during hip extension, abduction, and external rotation. However, it is unknown how altering the testing position influences hip muscle activity during these commonly performed assessments.

OBJECTIVES

To evaluate how hip sagittal plane position influences hip muscle activation and torque output.

STUDY DESIGN

Cross-sectional.

SETTING

Laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 22 healthy females (age = 22.1 [1.4] y; mass = 63.4 [11.3] kg; height = 168.4 [6.2] cm) were recruited.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Participants completed isometric contractions with surface electromyography on the superior and inferior gluteus maximus; anterior, middle, and posterior gluteus medius; biceps femoris, semitendinosus, adductor longus, and tensor fascia latae. Extension and external rotation were tested in 0°, 45°, and 90° of hip flexion and abduction was tested in -5°, 0°, and 45° of hip flexion. Repeated-measures analysis of variances were used for statistical analysis (P ≤ .01).

RESULTS

Activation of gluteal (P < .007), semitendinosus (P = .002), and adductor longus (P = .001) muscles were lesser for extension at 90° versus less flexed positions. Adductor longus activity was greatest during 90° of hip flexion for external rotation torque testing (P < .001). Tensor fascia latae (P < .001) and gluteus maximus (P < .001) activities were greater in 45° of hip flexion. Significant differences in extension (P < .001) and abduction (P < .001) torque were found among positions.

CONCLUSIONS

Position when assessing hip extension and abduction torque has an influence on both muscle activity and torque output but only muscle activity for hip external rotation torque. Clinicians should be aware of the influence of position on hip extension, abduction, and external rotation muscle testing and select a position most in line with their clinical goals.

A Contemporary Approach to Patellofemoral Pain in Runners

Patellofemoral pain (PFP) is among the most common injuries in recreational runners. Current evidence does not identify alignment, muscle weakness, and patellar maltracking or a combination of these as causes of PFP. Rather than solely investigating biomechanics, we suggest a holistic approach to address the causes of PFP. Both external loads, such as changes in training parameters and biomechanics, and internal loads, such as sleep and psychological stress, should be considered. As for the management of runners with PFP, recent research suggested that various interventions can be considered to help symptoms, even if these interventions target biomechanical factors that may not have caused the injury in the first place. In this Current Concepts article, we describe how the latest evidence on education about training modifications, strengthening exercises, gait and footwear modifications, and psychosocial factors can be applied when treating runners with PFP. The importance of maintaining relative homeostasis between load and capacity will be emphasized. Recommendations for temporary or longer-term interventions will be discussed. A holistic, evidence-based approach should consist of a graded exposure to load, including movement, exercise, and running, while considering the capacity of the individual, including sleep and psychosocial factors. Cost, accessibility, and the personal preferences of patients should also be considered.

THE SUCCESS OF RETURN TO SPORT AFTER SUPERIOR LABRUM ANTERIOR TO POSTERIOR (SLAP) TEARS: A SYSTEMATIC REVIEW AND META-ANALYSIS

Background

Reviews on superior labral anterior to posterior (SLAP) injuries have been reported in the literature. However, current reviews have not focused on the success of athletes return to their previous level of sport or athletic performance.

Hypothesis/Purpose

Systematically review return to sport (RTS) and return to sport at previous level (RTSP) proportions after SLAP injury while reporting any additional performance metrics and outcome measures.

Study Design

Systematic Review & Meta-Analysis.

Methods

A computer assisted literature search of MEDLINE, CINAHL, Embase and SportDiscus databases utilizing keywords related to RTS post-surgery for SLAP tear was implemented. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were utilized for study methodology. Quality assessment utilized the MINORS scale.

Results

Twenty-two studies (617 athletes) qualified for analysis. Based on limited evidence from level 3b to 4 studies, athletes RTS post intervention for SLAP injury occurred at a rate of 93% (95% CI:87 to 98%) and overall RTSP rate was 72% (95% CI:60 to 83%). The mean time to RTS post intervention was reported in 59% of studies at 6.9 ± 2.9 months. Patient reported outcome measures (PROM's) were reported in 86% of studies. There was limited reporting of performance statistics, rehabilitation guidelines, return to sport criteria, and information regarding SLAP diagnosis in the available studies. None of the included studies reported post-surgical athletic performance or career longevity.

Conclusions

Limited evidence suggests that less than three in four athletes return to their previous level of sport participation after SLAP injury intervention. Treatment success for an athlete with SLAP injury remains relatively unknown as only 59% of included studies clearly delineate RTS from RTSP and neither athletic performance nor career longevity were reported in any included studies. Future studies of higher quality are required for this determination.

Level of Evidence

Level 1a.

Limited Support for Trunk and Hip Deficits as Risk Factors for Athletic Knee Injuries: A Systematic Review With Meta-analysis and Best-Evidence Synthesis

OBJECTIVE

To determine whether neuromuscular deficits in trunk and hip-related function are risk factors for athletic knee injuries.

DESIGN

Etiology systematic review with meta-analysis.

LITERATURE SEARCH

Six online databases (MEDLINE, Web of Science, Embase, CINAHL, Scopus, and SPORTDiscus) were searched up to April 2019.

STUDY SELECTION CRITERIA

Studies assessing trunk and hip neuromuscular function as risk factors for knee injuries in healthy athletic populations were included.

DATA SYNTHESIS

Outcomes were synthesized quantitatively using meta-analysis of odds ratios, and qualitatively using best-evidence synthesis.

RESULTS

Twenty-one studies met the inclusion criteria. There was very low-certainty evidence that greater hip external rotation strength protected against knee injuries (odds ratio = 0.78; 95% confidence interval: 0.70, 0.87; P<.05). There was limited evidence that deficits in trunk proprioception and neuromuscular control, and the combination of excessive knee valgus and ipsilateral trunk angle when landing unilaterally from a jump, may be risk factors for knee injuries.

CONCLUSION

Most variables of trunk and hip function were not risk factors for injuries. Further research is required to confirm whether hip external rotation strength, trunk proprioception and neuromuscular control, and the combination of knee valgus angle and ipsilateral trunk control are risk factors for future knee injuries. J Orthop Sports Phys Ther 2020;50(9):476-489. Epub 1 Aug 2020. doi:10.2519/jospt.2020.9705.

Validity and reliability of 2-dimensional trunk, hip, and knee frontal plane kinematics during single-leg squat, drop jump, and single-leg hop in females with patellofemoral pain

OBJECTIVES

To investigate validity and between-session reliability of frontal plane trunk, hip, and knee kinematics during three functional tasks in females with patellofemoral pain (PFP).

DESIGN

Observational.

SETTING

Research Laboratory.

PARTICIPANTS

20 females with PFP (22.7 ± 3.2 years, 69.9 ± 9.2 kg, 167.7 ± 9.6 cm).

MAIN OUTCOME MEASURES

Trunk, hip, and knee frontal plane peak angles during the single leg squat (SLS), drop vertical jump (DVJ), and single leg hop (SLH) kinematics were evaluated using 2-dimensional (2D) and 3-dimensional (3D) motion capture. Participants returned to the lab one week later and competed a second 2D analysis of the functional tasks. Concurrent validity was assessed by evaluating relationship between 2D and 3D frontal plane kinematics with Pearson correlations. Between-session reliability was assessed by evaluating 2D kinematics with intraclass correlation coefficients by a single assessor.

RESULTS

Moderate to strong correlations (r = 0.55-0.76, p < .05) were found for frontal plane hip kinematics during all three tasks and the trunk during the SLH. Frontal plane kinematics demonstrated good to excellent test-retest reliability for each of the three tasks, (ICC _(2,1) = 0.70-0.90).

CONCLUSION

2D hip joint angles during the three functional tasks were the only valid frontal plane angles. Trunk, hip, and knee 2D frontal plane kinematics ranged between good-excellent reliability.

Gait deviations and muscle strength deficits in subjects with patellar instability

BACKGROUND

Abnormal tracking of the patella is a hallmark sign of patellar instability (PI). Gait deviations and strength deficits may exacerbate abnormal tracking. The identification of modifiable gait deviations and strength deficits can aid in developing more effective management strategies for individuals with PI. The purpose of this study was to identify modifiable gait and strength deficits in subjects with PI.

METHODS

32 subjects (16 PI, 16 controls, 3 males/13 females in each group, 21.1 years old, 23.5 BMI), performed an instrumented gait analysis while walking at 1.5 m per second. Subjects' peak hip adduction angles, external rotation angles, hip abduction moments, knee flexion angles, knee adduction angles, and knee extensor moments were measured during walking. Hip abduction, hip external rotation, and knee extension strength were assessed with a handheld dynamometer.

RESULTS

Individuals with PI displayed significantly lower peak knee adduction angles (1.8 ± 2.8° PI, 5.5 ± 4.5° control, p < .01) and peak hip abduction moments (0.2 ± 0.1 Nm/kg*m PI, 0.4 ± 0.1 Nm/kg*m control, p < .01). Subjects with PI were weaker in knee extension strength (14.5 ± 4.1 kg/m PI, 23.8 ± 7.2 kg/m control, p < .01), hip abduction strength (12.1 ± 2.0 kg/m PI, 17.8 ± 4.0 kg/m control, p < .01), and hip external rotation strength (5.5 ± 1.9 kg/m PI, 7.1 ± 1.3 kg/m control, p = .01).

CONCLUSION

Subjects with patellar instability have smaller joint moments and a more valgus knee position while walking. Coupled with deficits in muscle strength, this likely contributes to subjective reports of chronic patellar instability.

LEVEL OF EVIDENCE

III.