Gender differences in the incidence and prevalence of patellofemoral pain syndrome

Patellofemoral Disorders in Soccer Players

Patellofemoral disorders are common in the world of soccer and impact players across all levels and ages of the sport. Patellofemoral disorders encompass a spectrum of conditions, from anterior knee pain to patellar instability, and are often influenced by complex biomechanical factors and anatomic variations that can predispose to these conditions. In recent years, there has been a growing emphasis on injury prevention strategies and data-driven approaches, championed by organizations like the Union of European Football Associations and individual professional clubs. Conservative management remains the initial approach for many players, including physical therapy and supportive devices. However, surgical intervention, particularly in cases of recurrent patellar dislocations, is often necessary. The understanding of patellofemoral biomechanics in soccer continues to evolve and offers opportunities for more effective injury prevention and tailored treatment strategies. Despite the challenges, a comprehensive approach to patellofemoral disorders in soccer is essential to preserve player health, enhance performance, and sustain the sport's vitality.

Effects of pain exacerbation on postural control in women with patellofemoral pain during single leg squat: a cross-sectional study

BACKGROUND

The center of pressure (COP) excursion parameters are recognized as risk factors for the etiology and development of patellofemoral pain (PFP). The purpose of the present study measures the effect of pain exacerbation on COP excursion, and the correlation between pain intensity and COP excursion in women with PFP during single leg squat (SLS).

METHODS

Sixty patients with PFP participated in this cross-sectional study. The outcome measures were included pain intensity and COP excursion which evaluated in pre and post pain exacerbation during SLS. The COP parameters were evaluated during single leg squat in 60° of knee flexion. A paired t-test and MANOVA was used to compare pain intensity and COP excursion between the two conditions, respectively. Furthermore, A Pearson's correlation matrix was used to examine the relationship between pain intensity with COP excursion.

RESULTS

Statistical analysis showed that pain intensity (t = - 16.655, p < 0.001) and COP excursion (Wilks' Lambda = 0.225, p < 0.001) with medium effect size increased after PFJ loading. In addition, an excellent positive correlation was observed between increased in pain intensity and COP excursion (P < 0.001, r > 0.80).

CONCLUSION

After PFJ loading, women with PFP presented increases in the pain intensity, COP excursions, and sway velocity. In addition, there was an association between the increase in pain intensity and COP excursions. Clinicians aiming to improve postural control of patients with PFP could use kinesio taping as a short-term intervention and balance training to improvements in postural control at medium and long-term. Furthermore, emphasizing psychological factors to reducing kinesiophobia can be useful to restoring proper movement pattern, reducing pain and improving symptoms.

Is there a relationship between knee crepitus with quadriceps muscle thickness and strength in individuals with patellofemoral pain? A cross-sectional study

OBJECTIVE

To explore the relationship between knee crepitus, quadriceps muscle thickness and isometric strength in individuals with patellofemoral pain (PFP).

DESIGN

Cross-sectional.

PARTICIPANTS

Individuals with PFP.

MAIN OUTCOME MEASURES

Participants with PFP underwent assessments for presence, frequency and severity of knee crepitus. Real-time ultrasound images of the quadriceps muscles (rectus femoris, vastus medialis and lateralis) at rest and during contraction were obtained, muscle thickness was measured in both conditions. Maximal voluntary isometric contraction tests were performed to measure knee extensor strength. The relationship between knee crepitus and quadriceps muscle thickness and knee extensor strength was explored using logistic and linear regressions.

RESULTS

Sixty individuals with PFP were included (age: 24; 60% women; 38% with crepitus). Knee crepitus severity was related to rectus femoris and vastus medialis thickness during rest (R2 = 0.19 and 0.09, respectively) and contraction (R2 = 0.16 and 0.07, respectively) and with vastus lateralis during contraction (R2 = 0.08). Isometric knee extensor strength was not related to knee crepitus presence, frequency, or severity.

CONCLUSION

Higher severity of knee crepitus is related to lower quadriceps muscle thickness in individuals with PFP. There is no relationship between the presence and frequency of knee crepitus with quadriceps muscle thickness or knee extensor strength.

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.

Effects of neuromuscular electrical stimulation on patellofemoral pain: A randomized controlled trial

INTRODUCTION

Patellofemoral Pain (PFP) is a common dysfunction that can compromise the performance of daily activities. Neuromuscular electrical stimulation (NMES) has been proposed as a complementary tool in the therapeutic approach.

OBJECTIVE

To analyze the effects of adding NMES to therapeutic exercises in women with PFP.

METHODS

Randomized controlled trial involving 34 women with PFP (mean age 23.8 ± 4.1), randomly assigned to two groups: exercises combined with NMES (ESG) and exercises only (ExG). The ExG followed an exercise protocol, while the ESG performed the same exercises combined with NMES. Interventions were performed twice a week for eight weeks. Primary outcome measures included pain and functional disability, while secondary outcomes encompassed electromyographic activity of the quadriceps and hip abductors, along with isokinetic performance. Assessments were performed before the intervention, after 4 and 8 weeks from the start of the protocol and 8 weeks after the conclusion of the treatment.

RESULTS

We did not observe difference between the groups in any of the analyzed variables. Both groups showed a reduction in pain and an improvement in functional disability during intragroup comparisons.

CONCLUSION

A reduction in pain and an improvement in functional disability were observed; however, there was no additional effect of NMES.

TRIAL REGISTRATION

NCT03918863.

Effect of Sex and Lateral Ankle Sprain History on Dorsiflexion Range Of Motion Asymmetry During the Weight Bearing Lunge Test

Background

Reduced dorsiflexion range of motion (DFROM) which is commonly seen following lateral ankle sprain (LAS) has the potential to influence lower extremity biomechanics which have been linked to increased injury risk in the female athlete. Current research on the effect of sex and LAS history on DFROM is limited.

Hypothesis/Purpose

This study had three aims 1) to determine the effect of sex, leg dominance and LAS history on DFROM, 2) to determine the effect of sex and LAS history on magnitude of DFROM symmetry and 3) to examine the association of sex on direction (whether dominant or non-dominant limb had the higher DFROM) of symmetry.

Study Design

Cross-Sectional Study.

Methods

DFROM was measured bilaterally in 105 recreational athletes all participating in multidirectional sports using the tape measurement method during the weight bearing lunge test (WBLT). A mean of three measurements was used for analysis. A 3-way mixed ANOVA was carried out to determine the interaction between sex, LAS history and leg dominance on DFROM and a 2-way ANOVA for the effect of sex and LAS history on asymmetry. A chi-square test was used to determine the association of sex and direction of asymmetry.

Results

The results indicate no significant effect of sex, LAS history, and leg dominance on DFROM (p=0.65). Main effects were significant for sex and LAS on DFROM. The mean asymmetry for all participants was reported as 12.25±14.76cm. No significant effect of sex and LAS history on magnitude of asymmetry was reported. There was a significant association of sex and direction of asymmetry (χ2(1) = 11.26, p = 0.00). Sixty-five-point two percent of males were shown to have higher DFROM of their non-dominant limb compared to 75% of females who were higher in their dominant limb.

Conclusion

Findings from this study suggest that DFROM is affected by sex and LAS history. While females have increased DFROM compared to males, those with LAS history are more likely to have a decreased DFROM on the involved side. The results also indicate that interlimb asymmetries in DFROM are present in athletes, therefore practitioners should exercise caution when using bilateral comparisons in injury and return to play assessments.

Level of Evidence

2b.

Efficacy of Osteopathic Manipulative Treatment for Pain Reduction in Patients With Patellofemoral Pain Syndrome: A Meta-Analysis of Randomized Controlled Trials

Patellofemoral pain syndrome (PFPS) is among the most common causes of musculoskeletal pain in the United States. It is defined as retropatellar or peripatellar pain that is reproduced with functional activities that load the patellofemoral joint in a flexed position, such as stair climbing or squatting. While it presents in both adolescents and adults, it is commonly found in physically active individuals, such as athletes and military recruits. Exploring the role of osteopathic manipulative treatment (OMT) in PFPS is of particular interest given the absence of a definitive treatment and the poor long-term prognosis associated with PFPS. This meta-analysis includes three studies exploring the use of OMT to reduce pain in patients suffering from PFPS and exploring the efficacy of OMT as a primary intervention. In these studies, pain assessments, pre-treatment, and post-treatment follow-up of at least 30 days were performed using a 10-cm visual analog scale (VAS). The mean difference in pain between OMT and no treatment (NT) groups using the random effects model was -3.95 (-6.39; -1.50) with a p<0.01, suggesting OMT resulted in significant knee pain reduction in those with PFPS. A measure of heterogeneity, known as I2, was found to be high at 97%, which suggests caution should be taken when interpreting the overall results. Given the lack of definitive treatment and the poor long-term prognosis for PFPS, the authors suggest OMT provides an effective option for pain relief in patients with PFPS. Further research is needed to provide results that may be more clinically applicable or valuably interpreted.

Effects of high frequency strengthening on pain sensitivity and function in female runners with chronic patellofemoral pain

OBJECTIVE

To investigate the effects of a high frequency strengthening program on function, pain, and pain sensitization in female runners with chronic patellofemoral pain (PFP).

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Thirty female runners (mean age 32 ± 8.1 years) with chronic PFP completed an 8-week home strengthening program.

MAIN OUTCOME MEASURES

Variables assessed at baseline, 8-weeks, and 12 weeks included single leg step down test (SLSD), pain, Anterior Knee Pain Scale (AKPS), University of Wisconsin Running Injury and Recovery Index (UWRI), and quantitative sensory testing.

RESULTS

There was large and statistically significant improvement at 8 and 12 weeks for average knee pain (ηp2 = 0.334, p < 0.001), worst knee pain (ηp2 = 0.351, p < 0.001), SLSD (ηp2 = 0.161, p = 0.001), AKPS (ηp2 = 0.463, p < 0.001), and UWRI (ηp2 = 0.366, p < 0.001). A medium to large effect and statistically significant improvement in pressure pain threshold testing was found for all local and remote structures (ηp2 range, 0.110 to 0.293, range p < 0.001 to p = 0.009) at 8 and 12 weeks.

CONCLUSIONS

There was a significant decrease in local and remote hyperalgesia via mechanical and thermal pain sensitivity testing in female runners with chronic PFP. There was a large effect and significant improvement in self-reported pain and function.

Reliability of Tibial Tubercle-Trochlear Groove Distance for Assessing Tibial Tubercle Lateralization: A Study Comparing Different Anatomic References

Background

The tibial tubercle-trochlear groove (TT-TG) distance is a measurement used to quantitatively assess tibial tubercle lateralization (TTL), and it has important reference value for the treatment of patellar dislocation (PD). However, TT-TG distance accuracy has been questioned, so many new parameters have been proposed.

Purpose

To compare which of the TT-TG, tibial tubercle-midepicondyle (TT-ME), tibial tubercle-Roman arch (TT-RA), tibial tubercle-tibial intercondylar midpoint (TT-TIM), and tibial tubercle-mid inter-epicondyle trochlea intersection (TT-MIELTI) distances better reflect TTL in patients with PD.

Study Design

Cohort study (diagnosis); Level of evidence, 3.

Methods

A total of 96 patients who had undergone surgery for PD and 96 patients without PD (controls) were included in the study. The patients had all undergone computed tomography examination. The TT-TG, TT-ME, TT-RA, TT-TIM, TT-MIELTI distances and the TTL distance were measured independently by 2 surgeons in a blinded and randomized fashion. The t test was used to detect whether the parameters were significantly different between the 2 groups. The TTL distance was used as a reference value for lateralization of tibial tubercle. Pearson correlation coefficients were calculated to determine correlations between the defined measurements.

Results

The intra- and interobserver reliability of the defined measurements was excellent. All parameters except for TT-TIM distance were significantly larger in the PD group than the control group (P < .01 for all). There was a moderate correlation (r = 0.601) between the TT-TG distance and TTL, and other parameters were less correlated with TTL.

Conclusion

Among 5 the parameters tested, the TT-TG distance still had the highest correlation with TTL and was able to reflect TTL better in patients with PD. The role of TT-TIM distance in the assessment of PD needs further study.

Global research trends and hotspots in patellofemoral pain syndrome from 2000 to 2023: a bibliometric and visualization study

Background

Patellofemoral pain syndrome (PFPS) is a prevalent condition in sports medicine, and as sports competitions become more popular, the incidence of sports injuries is on the rise. Despite the increasing research on PFPS, there remains a lack of bibliometric analyses on this topic. The aim of this study was to identify the research hotspots and trends in the field of PFPS by reviewing 23 years of literature in this field.

Methods

By analyzing the literature on PFPS research from 2000 to 2023 in the core dataset of the Web of Science database and utilizing bibliometric tools like CiteSpace 6.1, VOSviewer 1.6.18, R-bibliometrix 4.6.1, Pajek 5.16, and Scimago Graphica 1.0.26, our aim was to gain insights into the current status and key areas of PFPS research. The study examined various aspects including the number of publications, countries, institutions, journals, authors, collaborative networks, keywords, and more. Through the visualization of relevant data, we also attempted to forecast future trends in the field.

Results

There were 2,444 publications were included in this visualization study, published in 322 journals by 1,247 authors from 818 institutions in 67 countries. The Journal of Orthopaedic and Sports Physical Therapy had the highest number of publications, with the USA leading in article count. La Trobe University contributed the most articles, while Rathleff MS and Barton CJ emerged as the most prolific authors. Hip and knee strength and core strength, lower extremity kinematics and biomechanics, females (runners), muscle activation, risk factors, gait retraining, clinical practice guidelines, and rehabilitation were research hotspot keywords.

Conclusion

Current research suggests that there is still significant potential for the development of PFPS research. Key areas of focus include the clinical effectiveness of combined hip and knee strengthening to address PFPS, characterization of lower limb kinematics and biomechanics, gait retraining, risk factors, and clinical practice guidelines. Future research could explore the effectiveness of innovative exercise therapies such as blood flow restricting training, gait retraining, and neuromuscular control training for PFPS improvement. Further investigation into gait retraining for runners, particularly females, and clinical efficacy study of a novel PRP formulation for the treatment of PFPS.

Sex differences in lower extremity kinematics during overhead and single leg squat tests

The Overhead Squat (OHS) and Single-Leg Squat (SLS) are two clinical tests used by practitioners to identify high-risk biomechanical movement patterns. Several published studies have reported sex differences in SLS performance; however, few have investigated variations during the OHS and none has measured kinematics with a marker-less motion capture system. Therefore, this study aimed to compare biomechanical movement patterns between male and female collegiate athletes during OHS and SLS testing. Seventy-five females and 58 male athletes completed OHS and SLS . A Microsoft Kinect sensor using Athletic Movement Assessment software (PhysiMax®) was used to measure kinematics. For the OHS, males displayed greater peak knee frontal plane projection angles (FPPA) (M:26°±10°, F:20°±8°; P < 0.05), peak hip flexion (M:-94°±14°, F:-87°±15°; P < 0.05), and peak trunk flexion angles (M:11°±11°, F:6°±9°; P < 0.05). For the SLS (dominant-limb), males displayed greater peak trunk flexion (M:32°±6°, F:27°±7°; P < 0.05). For the non-dominant limb, females displayed greater peak knee FPPA (F:-12°±9°, M:-8°±9°; P < 0.05) whereas males displayed greater peak trunk flexion angles (M:32°±5°, F:27°±7°; P < 0.05). These findings suggest the need for practitioners to develop sex-specific corrective exercise programmes in effort to improve lower extremity kinematics in athletes.

The relationship of behavioral and psychological traits with pain sensitivity in females with patellofemoral pain: A cross-sectional study

OBJECTIVE

The purpose of this study was to describe the relationship between behavioral and psychological traits with indicators of central sensitization in female runners with patellofemoral pain (PFP), and to determine if behavioral and psychological traits improve with strength training.

DESIGN

Cross-sectional study.

SETTING

University laboratory.

PARTICIPANTS

Twenty-eight active females (mean age 32 ± 8.1 years) with PFP completed testing at baseline, 8 weeks (post intervention), and 12 weeks.

MAIN OUTCOME MEASURES

Behavioral and psychological questionnaires included the General Anxiety Disorder-7, Patient Health Questionairre-9, Pain Catastrophizing Scale, Tampa Scale of Kinesiophobia-11, and Central Sensitization Inventory. Quantitative sensory testing (QST) measures were also collected. After baseline testing, subjects were instructed in a hip and knee strengthening intervention to be completed twice daily over 8 weeks.

RESULTS

A statistically significant improvement was found at 12 weeks for anxiety (p = .015; ηp (Boling et al., 2010) = 0.099) and kinesiophobia (p = .041; ηp (Boling et al., 2010) = 0.076). There was no significant improvement for depression, catastrophizing, or subjective central sensitization. No significant correlations were found between any of the behavioral and psychological questionnaires with baseline QST variables.

CONCLUSIONS

No relationship was found for behavioral and psychological characteristics with QST measures in female runners with persistent PFP.

Automated personalization of biomechanical knee model

PURPOSE

Patient-specific biomechanical models of the knee joint can effectively aid in understanding the reasons for pathologies and improve diagnostic methods and treatment procedures. For deeper research of knee diseases, the development of biomechanical models with appropriate configurations is essential. In this study, we mainly focus on the development of a personalized biomechanical model for the investigation of knee joint pathologies related to patellar motion using automated methods.

METHODS

This study presents a biomechanical model created for patellar motion pathologies research and some techniques for automating the generation of the biomechanical model. To generate geometric models of bones, the U-Net neural network was adapted for 3D input datasets. The method uses the same neural network for segmentation of femur, tibia, patella and fibula. The total size of the train/validation (75/25%) dataset is 18,183 3D volumes of size [Formula: see text] voxels. The configuration of the biomechanical knee model proposed in the paper includes six degrees of freedom for the tibiofemoral and patellofemoral joints, lateral and medial contact surfaces for femur and tibia, and ligaments, representing, among other things, the medial and lateral stabilizers of the knee cap. The development of the personalized biomechanical model was carried out using the OpenSim software system. The automated model generation was implemented using OpenSim Python scripting commands.

RESULTS

The neural network for bones segmentation achieves mean DICE 0.9838. A biomechanical model for realistic simulation of patellar movement within the trochlear groove was proposed. Generation of personalized biomechanical models was automated.

CONCLUSIONS

In this paper, we have implemented a neural network for the segmentation of 3D CT scans of the knee joint to produce a biomechanical model for the study of knee cap motion pathologies. Most stages of the generation process have been automated and can be used to generate patient-specific models.

Morphologic Evaluation of the Patella: The Impact of Gender and Age

Introduction

The patellofemoral joint is a complex joint that plays a crucial role in knee joint function and stability. This study aims to describe the MRI characteristics of the patellofemoral joint in Vietnamese adults.

Subjects and Methodology

A cross-sectional study was conducted on 280 patients at Hue UMP Hospital from May 2020 to May 2021. All patients underwent knee MRI using Siemens Magnetom Amira 1.5 Tesla. The evaluation parameters included the morphology of the patella and the femoral trochlea.

Results

The study found that the morphological parameters of the patellar joint varied significantly between genders and age groups. The mean largest patellar transverse diameter was 4.26 ± 0.37 cm, the average length of the lateral joint facet was 2.5 ± 0.26 cm, and the medial joint facet was 2.0 ± 0.25 cm. The patellar height was 4.07 ± 0.35 cm. The indexes of patellar morphology were higher in men than in women, except for the lateral-medial facet ratio. The most common Wiberg classification was type B (63.9%), followed by type C (25.4%), and type A was the least common (10.7%). There was a statistically significant difference in the patellar measurements between different age groups. There was a weak negative linear correlation between the dimensions of the largest transverse diameter, the length of the articular surface, the patellar articular angle, and the age of the patient. Additionally, there was a moderate inverse linear relationship between patellar height and patient age.

Conclusion

This study highlights the significant variations in patellar morphology based on gender and age. The findings emphasize the importance of careful assessment and consideration of these variations in the imaging evaluation of the patellofemoral joint.

Acute Effect of Dynamic and Gluteal Resistance Exercise Warm-up Protocols on Jump Landing Mechanics in College-Aged Females

ABSTRACT

Rauseo, ML, Feairheller, DL, LaRoche, DP, and Cook, SB. Acute effect of dynamic and gluteal resistance exercise warm-up protocols on lower-extremity jump landing mechanics in college-aged females. J Strength Cond Res 38(2): 259-265, 2024-Inadequate neuromuscular control of the femur by the gluteal musculature is associated with noncontact and overuse injuries to the knee. Acute bouts of resistance exercises targeting the gluteal musculature can be prescribed as part of a warm-up protocol with the goal of improving subsequent neuromuscular control and performance. The purpose of this study was to determine the effect that a warm-up protocol including moderate-intensity gluteal resistance exercises (GRE) has on single leg jump landing biomechanics. Seventeen healthy, college-aged, recreationally active females (mean ± SD ; age = 21.4 ± 1.9 years; height = 166.9 ± 5.7 cm; body mass = 62.5 ± 7.4 kg) performed 3 single leg hop trials per leg after completing no warm-up (CON), a dynamic warm-up (DWU), and a dynamic warm-up with gluteal resistance exercises (DWU + GRE) across 3 laboratory visits. Lower extremity kinetic and kinematic variables were assessed during single leg hops from the point of initial foot contact to deepest knee flexion. Biomechanical differences between dominant and nondominant limb landings were also assessed. Dominant limb hip internal rotation angle after DWU + GRE (2.03 ± 9.92°) was significantly greater ( p ≤ 0.05) compared with CON (-3.36 ± 7.74°). Peak knee adduction moment (56.8%), peak knee flexion angle (5.7%), and peak knee external rotation angle (17.0%) were significantly greater ( p ≤ 0.017) in the dominant limb, compared with the nondominant limb, across warm-up protocols. The combined DWU + GRE warm-up protocol did not have a substantial impact on landing biomechanics. Clinicians prescribing GRE before activity should not expect significant changes in movement patterns after a single bout.

Effects of adding neuromuscular electrical stimulation to functional training on muscle recruitment, pain reduction, and knee joint function in patellofemoral pain syndrome patients

BACKGROUND

Impaired lower extremity motor function and knee pain are common concerns in patients with patellofemoral pain syndrome (PFPS). It is essential to plan therapeutic techniques to therapy PFPS. The objective of this study was to determine the effect of neuromuscular electrical stimulation (NMES) combined with functional training on pain, lower extremity function and muscle recruitment in patients with PFPS.

METHODS

Twenty-four PFPS patients (male-13, female-11) were selected to conduct this study finally. Two groups were formed: the control group (n = 12) which included functional training only and the experimental group (n = 12) which functional training along with NMES-in both groups interventions were performed for 45 minutes/session, 3 days/weeks for 6 weeks. The functional training consisted of warm-up activities, strength training, balance training, and relaxation activities. All patients were evaluated with surface electromyography testing system for the root mean square and integrated electromyography of vastus medial oblique (VMO), vastus lateralis (VL), and VMO/VL ratio, visual analog scores (VAS) for pain, and Kujala functional score for knee joint function before and after 6 weeks. Normality was tested for all outcome variables using Shapiro-Wilk test. Nonparametric (Mann-Whitney U test and Wilcoxon signed-rank test) tests were used to analyze data. A 2-way analysis of variance with repeated measures (group*time) was applied to analyze the data.

RESULTS

A significant increases (P < .001) root mean square and integrated electromyography of VMO, VMO/VL ratio, and Kujala score in both groups, For VAS scores, significant decreases was observed in both groups. When both groups were compared, greater improvement (P < .05) was observed in the experimental group in comparison the control group for both knee pain, lower extremity function and muscle recruitment. However, there was no difference in VL muscle recruitment between the 2 groups.

CONCLUSIONS

Functional training and NMES combined with functional training are helpful to improve pain, knee function and muscle recruitment of PFPS patients. NMES combined with functional training was more effective compared to the control group. This may help clinical trialists to use different NMES to synchronize other interventions in future studies to enhance rehabilitation efficacy in PFPS patients through passive training versus active stimulation.

Interaction of Biomechanical, Anthropometric, and Demographic Factors Associated with Patellofemoral Pain in Rearfoot Strike Runners: A Classification and Regression Tree Approach

BACKGROUND

Patellofemoral pain (PFP) is among the most common injuries in runners. While multiple risk factors for patellofemoral pain have been investigated, the interactions of variables contributing to this condition have not been explored. This study aimed to classify runners with patellofemoral pain using a combination of factors including biomechanical, anthropometric, and demographic factors through a Classification and Regression Tree analysis.

RESULTS

Thirty-eight runners with PFP and 38 healthy controls (CON) were selected with mean (standard deviation) age 33 (16) years old and body mass index 22.3 (2.6) kg/m2. Each ran at self-selected speed, but no between-group difference was identified (PFP = 2.54 (0.2) m/s x CON = 2.55 (0.1) m/s, P = .660). Runners with patellofemoral pain had different patterns of interactions involving braking ground reaction force impulse, contact time, vertical average loading rate, and age. The classification and regression tree model classified 84.2% of runners with patellofemoral pain, and 78.9% of healthy controls. The prevalence ratios ranged from 0.06 (95% confidence interval: 0.02-0.23) to 9.86 (95% confidence interval: 1.16-83.34). The strongest model identified runners with patellofemoral pain as having higher braking ground reaction force impulse, lower contact times, higher vertical average loading rate, and older age. The receiver operating characteristic curve demonstrated high accuracy at 0.83 (95% confidence interval: 0.74-0.93; standard error: 0.04; P < .001).

CONCLUSIONS

The classification and regression tree model identified an influence of multiple factors associated with patellofemoral pain in runners. Future studies may clarify whether addressing modifiable biomechanical factors may address this form of injury.

Comparison of tactile acuity between patients with chronic patellofemoral pain with central sensitization and healthy persons: A cross-sectional study

BACKGROUND

Patellofemoral pain (PFP) is a common multifactorial condition in young and physically active people.

OBJECTIVE

The occurrence of central sensitization may play an important role in sensory disturbance. This study was designed to investigate, in patients with chronic PFP, the presence of disturbances in tactile acuity with central sensitization.

METHODS

Thirty patients with chronic PFP and 30 matched healthy controls entered this cross-sectional study. Graphesthesia (numerical score), two-point discrimination (mm), and point-to-point sensation (mm) were assessed in all participants.

RESULTS

The results of between-group comparisons showed that there were significant differences between the involved knee in patients with chronic PFP and healthy participants in graphesthesia (median = 13 [case], 19 [control]; p < .001), two-point discrimination (median = 25.8 [case], 20.3 [control]; p < .001), and point-to-point sensation (median = 14.5 [case], 6.2 [control]; p < .001). There was also a significant difference in graphesthesia between the non-involved knee in patients with chronic PFP and healthy participants (median = 17 [case], 19 [control]; p = .003). The results of within-group comparisons revealed a significant difference in graphesthesia, two-point discrimination, and point-to-point sensation between the involved and non-involved knee in patients with chronic PFP (p < .001). Moreover, there was a positive correlation between two-point discrimination and pain in patients with chronic PFP (r = 0.446, p = .014).

CONCLUSION

The findings of this study reveal that there is a sensory deficit in patients with chronic PFP. Because sensory information is necessary for motor control and pain perception, we can assume that clinical symptoms in these patients are related to sensory deficits.

Persons with patellofemoral pain exhibit altered hip abductor muscle recruitment while performing hip abductor exercises

INTRODUCTION

Strengthening of the hip abductors has been advocated for persons with patellofemoral pain (PFP). It is not clear if these individuals activate the hip abductor muscles appropriately to achieve the desired therapeutic effects.

OBJECTIVE

To compare activation of the hip abductor muscles between persons with and without PFP during the performance of hip abductor exercises.

METHODS

Thirty-two individuals participated (12 with PFP and 20 without PFP). The average age (± standard deviation) was 29.7 ± 5.9 years for the PFP group and 28.1 ± 6.9 for the control group. Electromyographic (EMG) signals from the gluteus medius (GMED), superior gluteus maximus (SUP-GMAX), and tensor fascia lata (TFL) were obtained using fine-wire electrodes while participants performed 11 different exercises. Normalized EMG activity of each muscle was compared between groups across all exercises.

RESULTS

When averaged across all exercises, persons with PFP exhibited significantly greater EMG activity of TFL (mean = 25.3% MVIC; 95% CI = 19.2, 31.3) compared to those without PFP (mean = 17.6% MVIC; 95% CI = 12.8, 22.4) and significantly lower EMG activity of SUP-GMAX (mean = 16.4% MVIC; 95% CI = 11.0, 22.0) compared to those without PFP (mean = 25.4% MVIC; 95% CI = 21.0, 29.8). Persons with PFP exhibited lower EMG activity of GMED, but only for 3 out of the 11 exercises evaluated (hip abduction, hip hike, step-up).

CONCLUSION

Compared to persons without PFP, those with PFP exhibited activation differences during the performance of exercises used to target the hip abductors. Our results highlight the need for activation training prior to the initiation of strengthening exercises to achieve desired therapeutic effects.

Sex differences in pelvis, thigh, and shank coordination during walking

Differences in lower limb kinematics between males and females during functional activities may be attributed to sex differences in the incidence of patellofemoral pain, which is more common in females. To better comprehend the knee joint motion, it is necessary to understand both inter-segmental coordination patterns and angular amplitude. This exploratory study aimed to assess sex differences in pelvis-thigh and thigh-shank coordination patterns in the frontal and horizontal planes during walking. Data regarding the kinematic characteristics of the pelvis, thigh, and shank segments were collected from 26 males and 26 females performing walking at self-selected speeds using a 3D motion capture system. Furthermore, we compared the kinematics of the pelvis, thigh, and shank during walking as well as the pelvis-thigh and thigh-shank coordination patterns in the frontal and horizontal planes during the stance phase between males and females. Compared to males, females had greater thigh adduction (p < 0.001) and internal rotation (p < 0.001) throughout the stance phase; significantly greater frequency of the pelvis-thigh anti-phase pattern in the frontal plane in the early (p = 0.002) and mid-stance (p = 0.003); and significantly greater thigh-shank anti-phase pattern in the frontal plane in the early (p = 0.001) and mid-stance (p = 0.015). These results suggest the presence of sex differences in the inter-segmental coordination of the pelvis and lower limb during walking. However, as this study could not determine a causal relationship between female sex and knee joint injury, further longitudinal studies are needed to determine the effects of differences in coordination patterns on the pathophysiology of the injury and pain generation.

Sagittal trunk excursion and lumbar repositioning error between female and male patients with patellofemoral pain syndrome

Background

Patellofemoral pain syndrome (PFPS) is a challenging clinical problem affecting adults, adolescents, and physically active populations. PFPS impacts the patient's trunk kinematics in the frontal plane. Previous studies have found gender-based biomechanical differences in patients with PFPS; however, sagittal trunk kinematics during mini-squats and lumbar proprioception in PFPS have not been studied previously.

Objectives

To investigate sagittal trunk excursion (It is defined as the sagittal trunk flexion angle from the start to the end of the mini squat) during mini-squats as well as lumbar repositioning error between individuals with and without PFPS, and determine gender differences in the outcome variables.

Methods

A sample of 56 participants aged 18-25 years was enrolled; 30 with PFPS (13 males, 17 females) and 26 asymptomatic controls (11 males, 15 females). The sagittal trunk excursion during mini-squats was examined by two-dimensional (2D) photographic analysis using Surgimap software. Active lumbar flexion repositioning error was assessed using an isokinetic dynamometer.

Results

For sagittal trunk excursion, no significant main effect of group was observed (p = 0 . 136 ). On the other hand, the main effect was significant for gender (p = 0 . 005 ), as was the interaction effect. Compared to the control group, the PFPS group showed significantly (p = 0 . 01 ) lower sagittal trunk excursion in females than in males during mini-squats. For active lumbar flexion repositioning error, no evidence was found for significant main or interaction effects (p > 0 . 05 ).

Conclusion

Females with PFPS exhibit a more erect sagittal trunk posture than males during mini-squats. Trunk posture should be considered during weight-bearing activities in PFPS, and gender-specific assessment protocols should be developed.

Patellofemoral pain in general practice: the incidence and management

BACKGROUND

Patellofemoral pain (PFP) is a nontraumatic knee problem primarily observed in physically active adolescents. The objective of this study was to determine the incidence and management of PFP in children and adolescents in general practice.

METHODS

A retrospective cohort study was conducted using a regional primary care database containing full electronic health records of over 300,000 patients. Patients with a new PFP diagnosis between the years 2013 and 2019 were extracted using a search algorithm based on International Classification of Primary Health Care coding and search terms in free text. Data on the management of PFP were manually checked and analysed. In addition, a sub-analysis for chronic and nonchronic PFP patients was performed.

RESULTS

The mean incidence of PFP over the study period was 3.4 (95% CI 3.2-3.6) per 1,000 person years in the age group of 7-24 years. Girls had a higher incidence rate (4.6 [95% CI 4.3-5.0]) compared to boys (2.3 [95% CI 2.1-2.5]). Peak incidence was at age 13 years for both sexes. The most commonly applied management strategy was advice (55.1%), followed by referral to physiotherapy (28.2%), analgesics prescription (10.4%), and referral to the orthopaedic surgeon (8.9%). No differences were found in age, sex, and treatment between chronic and nonchronic PFP patients.

CONCLUSIONS

The average Dutch general practitioner sees approximately 1.4 new child or adolescent with PFP per year. Overall management strategies were in concordance with current Dutch general practice guideline on nontraumatic knee problems. More insight should be gained in the population with chronic complaints.

Sex Differences in Knee Extensor Neuromuscular Function in Individuals With and Without Patellofemoral Pain

BACKGROUND

Impaired knee extensor neuromuscular function has been frequently observed in individuals with patellofemoral pain (PFP); however, few researchers have aimed to understand the influence of sex on knee extensor neuromuscular function in this pathological population. The authors aimed to determine whether there are differences in knee extensor neuromuscular function between sexes in individuals with and without PFP.

HYPOTHESIS

Women with PFP would exhibit greater deficits in knee extensor neuromuscular function than men with PFP, compared with sex-matched individuals without PFP.

STUDY DESIGN

Cross-sectional, case-control study.

LEVEL OF EVIDENCE

Level 4.

METHODS

A total of 110 individuals were classified into 4 groups: women with PFP (n = 25); men with PFP (n = 30); women without PFP (n = 25); and men without PFP (n = 30). Knee extensor strength (isometric peak torque [PT]), activation (central activation ratio), early, late, and total phase rate of torque development (RTD0-100, RTD100-200, and RTD20-80%), and endurance (isokinetic average PT) were assessed using an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of variance (sex by PFP).

RESULTS

Both women and men with PFP exhibited lower knee extensor strength, activation, early, late, and total phase RTD, and endurance versus sex-matched individuals without PFP (P < 0.05 for all comparisons). Women with PFP exhibited lower early phase (7.91 ± 2.02 versus 9.78 ± 2.43 N·m/s/kg; P < 0.01; Cohen d = 0.83), late phase (5.34 ± 1.02 versus 7.28±2.28 N·m/s/kg; P < 0.01; Cohen d = 1.37), and total phase (7.40 ± 2.57 versus 8.72 ± 2.57 N·m/s/kg; P = 0.03; Cohen d = 0.51) RTD than men with PFP.

CONCLUSION

Compared with sex-matched pain-free individuals, women with PFP displayed lower RTD than men with PFP. Clinicians should note that among individuals with PFP, women are more likely to experience a greater impairment in their knee extensor torque-generating capacity than men.

CLINICAL RELEVANCE

Additional treatment strategies that effectively improve the ability to rapidly generate torque should be developed and implemented, especially when treating women with PFP.

Medial Knee Joint Space in Relation to Joint Function and Early Knee Pain in 20-45-Year Adults: A Cross Sectional Study

Background

Anterior knee pain is very common in the young and active age groups but there are no significant studies on the normal population. Therefore, the objective of the study was to understand the relation between medial knee joint space to the development of knee pain and functional disability with special reference to the 20-45-year age group.

Materials and methods

250 cases with mean age of 36.36 years presenting with knee pain for at least 1 month were included in this prospective study (July 2021 and June 2022) and were asked to self-complete questionnaires on knee pain which included KNEST, AKPQ, VAS and IPAQ. Patients underwent X-rays of bilateral knees in AP view with weight bearing and then medial and lateral knee joint spaces were calculated.

Results

There was a higher incidence of knee pain in women compared to men. The average medial and lateral joint space widths (MJSW and LJSW) of the right knee were 4.22 mm and 4.57 mm, respectively. For the left knee it was 4.19 mm and 4.42 mm, respectively. There is a decrease in MJSW with increasing age, level of pain and BMI. Also, with an increase in physical activity, there was a higher incidence of knee pain.

Conclusion

Overuse injuries are the main cause of knee pain in this age group. There is a significant association between medial joint space width and age, gender, level of pain, and BMI. Rising BMI patterns at a young age, leads to an increase in physical activity, which in turn leads to early knee pain and also predisposes to osteoarthritis.

Inequalities in the Evaluation of Male Versus Female Athletes in Sports Medicine Research: A Systematic Review

BACKGROUND

Female sports participation continues to rise; however, inequalities between male and female athletes still exist in many areas and may extend into medical research.

PURPOSE

The purpose of this study was to (1) compare the number of published studies evaluating male versus female athletes in various sports and (2) identify which co-ed sports currently underrepresent female athletes in the sports medicine literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

All nonreview research studies published from 2017 to 2021 in 6 top sports medicine journals were considered for inclusion. Sports medicine studies were included that isolated athletes, reported study outcomes specific to male and/or female patients, provided study outcomes for specific sports, and evaluated ≤3 different sports. The total number of studies reporting on male and/or female athletes were compared for all sports, and odds ratios (ORs) were calculated. Comparisons of study design, level of sports participation, outcomes assessed, and study quality were also made according to participant sex.

RESULTS

Overall, 669 studies were included the systematic review. Most studies isolated male athletes (70.7%), while 8.8% isolated female athletes and 20.5% included male and female athletes. Female athletes were more frequently studied in softball and volleyball, while male athletes were more commonly researched in baseball, soccer, American football, basketball, rugby, hockey, and Australian football. Notably, male athletes were largely favored in baseball/softball (91% vs 5%; OR = 18.2), rugby (72% vs 5%; OR = 14.4), soccer (65% vs 15%; OR = 4.3), and basketball (58% vs 18%; OR = 3.2).

CONCLUSION

Sports medicine research has favored the evaluation of male athletes in most sports, including the majority of co-ed sports. Potential reasons for this inequality of research evaluation include availability of public data and database data, financial and promotional incentives, a high percentage of male sports medicine clinicians and researchers, and sex biases in sport. While the causes of these differences are multifaceted, researchers should consider both sexes for study inclusion whenever possible, and journals should support a more balanced representation of research publications regarding male and female athletes.

Males and females have similar neuromuscular coordination strategies of the quadriceps during fatiguing repeated all-out cycling

Introduction

An imbalance of vastus medialis (VM) and vastus lateralis (VL) muscle activation and patterns of dyscoordination may contribute to the sex discrepancy in the incidence of patellofemoral pain syndrome (PFPS). While some studies have examined sex-specific VM/VL coordination strategies in some tasks, no previous studies have examined sex-specific VM/VL coordination strategies during repeated sprint exercise (RSE).

Methods

In this study, asymptomatic young adults (N = 39, 19 females) completed a RSE protocol consisting of 10 × 10 s all-out cycling interspersed by 30 s of passive rest. Electromyographic (EMG) signals from the VM and VL muscles were recorded throughout exercise.

Results

VM:VL ratio did not change with fatigue and was not different between the sexes. From sprint 1 to 10, VM-VL onset delay increased from 9.62 to 16.95 ms and from 19.28 to 45.09 ms in males and females, respectively (p < 0.001); however, no sex difference was found (p = 0.524). Muscle activation amplitude plateaued at different sprint repetitions in males and females while mechanical work plateaued at similar repetitions.

Discussion

These findings suggest that sex differences in the incidence of PFPS may not be influenced by VM/VL muscle coordination as assessed by EMG.

Dose-response effect of lower limb resistance training volume on pain and function of women with patellofemoral pain: A systematic review and meta-regression

OBJECTIVE

Analyze whether the effects of lower limb resistance training on pain and self-reported function were associated with the exercise volume prescribed for women with patellofemoral pain (PFP).

METHODS

A systematic search was undertaken in four databases from inception to May 2023. Eligible trials examined the effects of resistance training programs on pain (visual analogue scale or numerical pain scale) and function (Anterior Knee Pain Scale) in women with PFP. Meta-analysis was undertaken with a random-effects model. The association of resistance training volume-related variables with mean difference effects on pain and function were tested by exploratory univariable meta-regression models.

RESULTS

From 1,404 estudies retained for screening after duplicate removals, 16 studies (579 patients) were included. Changes in knee pain were inversely associated with weekly training frequency (β = 0.5 ± 0.2, P = 0.012). No associations were found between the amount of resistance exercise prescribed per session or per week and effects on pain. Changes in function were associated with the number of sets per week (β = 0.1 ± 0.1, P = 0.044) and number of sets per session (β = 0.6 ± 0.2, P < 0.001) over the intervention. Most favorable results were achieved with 17 to 27 sets per session and >45 sets per week.

CONCLUSIONS

The amount of prescribed resistance exercise does not seem to be critical for pain reduction in women with PFP. However, our findings support a dose-response effect in terms of improving function.

The Effect of Bicycle Saddle Widths on Saddle Pressure in Female Cyclists

Choosing an unsuitable bicycle saddle increases the saddle pressure and discomfort during cycling. Women contract sports injuries more easily than men during cycling owing to their anatomy. To investigate the effect of saddle widths on the saddle pressure in female cyclists. Ten healthy women with an average age of 20.7 ± 1.3 years, height of 162 ± and 5.9 cm, weight of 56.1 ± 7.5 kg, and a sciatic bone width of 15.5 ± 1.4 cm were recruited for this study. The distributions of saddle pressure for four different saddle widths (i.e., narrow, moderate, wide, and self-chosen) were recorded using a saddle pressure mat. Participants were instructed to pedal steadily with a frequency of 90 RPM and a load of 150 watts. Thirty seconds of riding data was randomly retrieved for analysis. The trials were conducted with a counter-balanced design to minimize random errors. One-way repeated measures ANOVA was used to compare the saddle pressure of different saddle widths, and the significance level was set at α = 0.05. When wide saddles were used, the maximum and average pressure on the right surface of the posterior ischium were lower than those with narrow (p = 0.001, p = 0.012) and moderate (p = 0.016, p = 0.019) saddles. The area of pressure on the pubic bone was smaller when using a wide saddle than when using narrow (p = 0.005) and moderate (p = 0.018) saddles, and the area of pressure on the right posterior sciatic bone was larger under the wide saddle than under the narrow (p = 0.017) and moderate (p = 0.036) saddles. The average force was greater with the moderate saddle than with the wide (p = 0.008) and self-chosen (p = 0.025) saddles. Using a saddle with a width that is longer than the width of the cyclist's ischium by 1 cm can effectively improve the distribution of saddle pressure during riding, while providing better comfort.

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.

Electromyostimulation With Blood Flow Restriction for Patellofemoral Pain Syndrome in Active Duty Military Personnel: A Randomized Controlled Trial

INTRODUCTION

The high prevalence of patellofemoral pain in military service members results in strength loss, pain, and functional limitations during required physical performance tasks. Knee pain is often the limiting factor during high-intensity exercise for strengthening and functional improvement, thus limiting certain therapies. Blood flow restriction (BFR) improves muscle strength when combined with resistance or aerobic exercise and may serve as a possible alternative to high-intensity training during recovery. In our previous work, we showed that Neuromuscular electrical stimulation (NMES) improves pain, strength, and function in patellofemoral pain syndrome (PFPS), which led us to ask whether the addition of BFR to NMES would result in further improvements. This randomized controlled trial compared knee and hip muscle strength, pain, and physical performance of service members with PFPS who received BFR-NMES (80% limb occlusion pressure [LOP]) or BFR-NMES set at 20 mmHg (active control/sham) over 9 weeks.

METHODS

This randomized controlled trial randomly assigned 84 service members with PFPS to one of the two intervention groups. In-clinic BFR-NMES was performed two times per week, while at-home NMES with exercise and at-home exercise alone were performed on alternating days and omitted on in-clinic days. The outcome measures included strength testing of knee extensor/flexor and hip posterolateral stabilizers, 30-second chair stand, forward step-down, timed stair climb, and 6-minute walk.

RESULTS

Improvement was observed in knee extensor (treated limb, P < .001) and hip strength (treated hip, P = .007) but not flexor over 9 weeks of treatment; however, there was no difference between high BFR (80% LOP) and BFR-sham. Physical performance and pain measures showed similar improvements over time with no differences between groups. In analyzing the relationship between the number of BFR-NMES sessions and the primary outcomes, we found significant relationships with improvements in treated knee extensor strength (0.87 kg/session, P < .0001), treated hip strength (0.23 kg/session, P = .04), and pain (-0.11/session, P < .0001). A similar set of relationships was observed for the time of NMES usage for treated knee extensor strength (0.02/min, P < .0001) and pain (-0.002/min, P = .002).

CONCLUSION

NMES strength training offers moderate improvements in strength, pain, and performance; however, BFR did not provide an additive effect to NMES plus exercise. Improvements were positively related to the number of BFR-NMES treatments and NMES usage.

Effects of a proprioceptive focal stimulation (Equistasi®) on reducing the biomechanical risk factors associated with ACL injury in female footballers

Introduction

Football presents a high rate of lower limb injuries and high incidence of Anterior Cruciate Ligament (ACL) rupture, especially in women. Due to this there is the need to optimize current prevention programs. This study aims to verify the possibility to reduce the biomechanical risk factors associated with ACL injury, through the application of proprioceptive stimulation by means of the Equistasi® device.

Methods

Ten elite female footballers were enrolled and received the device for 4 weeks (5 days/week, 1h/day). Athletes were assessed directly on-field at four time points: T0 and T1 (evaluation without and with the device), T2 (after 2 weeks), T4 (after 4 weeks) while performing two different tasks: Romberg Test, and four sidestep cutting maneuvers bilaterally. Seven video cameras synchronized with a plantar pressure system were used, thirty double colored tapes were applied on anatomical landmarks, and three dimensional coordinates reconstructed. Vertical ground reaction forces and center of pressure data were extracted from the plantar pressure insoles. Hip, knee, and ankle flexion-extension angles and moments were computed as well as abd-adduction joint torques. From the Romberg Test both center of pressure descriptive variables and frequency analysis parameters were extracted. Each variable was compared among the different time frames, T1, T2 and T4, through Friedman Test for non-parametric repeated measures (p<0.05); Wilcoxon Signed Rank Test was used for comparing variables between T0 and T1 (p<0.05) and across the different time frames as follows: T1-T2, T2-T4 and T1-T4.

Results

Statistically significant differences in both posturographic and biomechanical variables between the assessment at T0 and T1 were detected. Reduced hip and knee abduction torques were revealed in association with reduced both ground reaction forces and ankle dorsiflexion torque from T1 up to T4.

Discussion

The proprioceptive stimuli showed to have the potential to improve cutting biomechanics mainly with respect to the ligament and quadriceps dominance theories. Results of the present study, even if preliminary and on a small sample size, could be considered promising towards the inclusion of proprioceptive training in injury prevention programs.

Knee skin temperature response of patients with bilateral patellofemoral syndrome before and after heat and cold stress

Patellofemoral Pain Syndrome is characterized by the presence of pain in the front area of the knee, which occurs when performing common activities such as climbing stairs, and bending the knees, among others. The objective of this research was to evaluate the detection capability of infrared thermography in patients with Patellofemoral Pain Syndrome, in the baseline state, as well as after the application of thermal stress. The investigation was conducted in 48 patients, who were subdivided into four groups (n = 12). Two subgroups were healthy patients and two with Patellofemoral Pain Syndrome. For the diagnosis of the syndrome, a manual evaluation was performed using the Zohlen test and Q angle measurement. Subsequently, cold stress was applied for 10 min to a healthy subgroup and an experimental subgroup. The remaining two subgroups were subjected to heat stress for 15 min. Thermographic images of the lower extremities were acquired at seven time points, at baseline, immediately after application of thermal stress and then every 3 min until 15 min were completed. It was observed that patients presented Patellofemoral Pain Syndrome bilaterally. After statistical analysis, it was found that there were no significant differences in baseline temperature between the groups. However, for heat stress, a higher temperature was observed in the group with Patellofemoral Pain Syndrome (p < 0.05) in the recovery period, and in the case of cold stress, only a lower temperature in the left knee immediately after the application. In conclusion, it is not possible to detect patellofemoral syndrome bilaterally in the baseline state by thermography and neither is it evident in cold stress. However, after heat stress, thermal recovery is lower for the PFPS group, so it would be susceptible to detection.

Effects of an online program including mindfulness, exercise therapy and patient education compared to online exercise therapy and patient education for people with Patellofemoral Pain: protocol for a randomized clinical trial

BACKGROUND

Patellofemoral pain (PFP) is a common knee disorder that causes persistent pain, lower self-reported function and quality of life. People with PFP also present with altered psychological factors, which are associated with higher levels of pain and dysfunction. Mindfulness-based interventions (MBI) generally consist of meditative practices developed to provide a holistic approach to chronic conditions. However, the effects of MBI on clinical and psychological outcomes for people with PFP remains understudied.

METHODS

This assessor-blinded, parallel, two-arm randomized clinical trial aims to investigate the effects of adding an 8-week online MBI program to exercise therapy and patient education on clinical and psychological factors for people with PFP. We also aim to investigate whether psychological factors mediate changes in pain and function. Sixty-two participants with PFP will be recruited and randomized into one of two treatment groups (Mindfulness or Control group). Both groups will receive an 8-week intervention involving exercise therapy and education delivered through an online platform. The Mindfulness group will additionally receive a MBI component including formal and informal practices. Outcomes will be assessed online at baseline, intervention endpoint (follow-up 1) and 12 months after intervention completion (follow-up 2). Comparisons between groups will be performed at all time points with linear mixed models. A mediation analysis will be performed using a 3-variable framework.

DISCUSSION

Exercise therapy and patient education are considered the "best management" options for PFP. However, unsatisfactory long-term prognosis remains an issue. It is known that people with PFP present with altered psychological factors, which should be considered during the evaluation and treatment of people with PFP. Adding a MBI to the current best treatment for PFP may improve short and long-term effects by addressing the underlying psychological factors.

TRIAL REGISTRATION

Registro Brasileiro de Ensaios Clínicos (ReBEC) RBR-4yhbqwk, registered in April 6, 2021.

Physiotherapeutic interventions on quadriceps muscle architecture in patello-femoral pain syndrome

Quadriceps weakness and morphological alteration is a documented phenomenon that can have a major impact on strength and functional performance of PFPS patients. An effective and trustworthy non-invasive technique for measuring the quadriceps muscle's anatomy and architecture is B- Mode Ultrasonography. The aim of the study is to assess and compare the effectiveness of neuromuscular electrical stimulation application, quadriceps strengthening and in combination on the quadriceps muscle architecture and functional capacity in patients with Patello femoral pain syndrome. One hundred and twenty-four participants aged 18 - 40 years old with anterior knee pain were included. Participants were randomly allocated into four groups. Group A participants were given NMES, group B were given QS, group C were given combination therapy (NMES+QS) and group D was control group. Cross sectional area, Fascicle length and pennation angle were measured using B-Mode (2D) ultrasound for Quadriceps Femoris muscle. Knee function and pain were assessed using Kujala score and VAS. All parameters were evaluated before and after the intervention. The mean age, weight, height and BMI of control, NMES, QS and NMES+QS were not statistically significant (P = 0.881, 0.960, 0.951 and 0.953) which shows that the control and experimental groups were homogenous. Combination group showed significant improvement when compared to QS group followed by NMES group. Control group did not show any improvement. Neuromuscular Electrical Stimulation in combination with quadriceps strengthening showed a better outcome than in isolation on quadriceps muscle architecture after 10 weeks.

Rehabilitation of anterior knee pain in the pregnant athlete: Considerations and modifications by trimester

BACKGROUND

Anterior knee pain is a common symptom many females experience during pregnancy. There are several musculoskeletal changes that occur in anatomy and physiology throughout the course of pregnancy that impact the lower extremity kinetic chain. Pregnant athletes, recreational through competitive, who attempt to maintain a high activity level through each trimester may be at increased risk for anterior knee pain due to a greater demand for lumbopelvic and hip stabilization.

CLINICAL QUESTION

What are the evidence-driven rehabilitation guidelines and specific modifications needed to treat anterior knee pain in the female athlete during each trimester of pregnancy?

KEY RESULTS

We aim to provide an overview of rehabilitation treatment guidelines for pregnant females with anterior knee pain, presenting specific physiological changes and rationale for modifications, discussed by trimester. We recommend our program be conducted under the supervision of a physical therapist working closely with the athlete's obstetrics and sports medicine team.

CLINICAL APPLICATION

The number of women who are active during pregnancy is increasing. We provide an overview of the guidelines and considerations for treating women with anterior knee pain during a healthy and uneventful pregnancy.

Determination of Standard Values for Knee Version in a Healthy Population

BACKGROUND

Different measures are used to describe relevant anatomic variations that can result in patellofemoral instability and disorders. Knee version, the relative rotational alignment between the femur and tibia in the axial plane at the level of the knee, may have a decisive effect on the kinematics of the patellofemoral joint. However, data regarding the values of knee version are currently lacking.

PURPOSE

This study aimed to determine standard values for knee version in a healthy population.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 100 healthy volunteers (50 male and 50 female) without patellofemoral disorders or lower extremity malalignment were included in this study and underwent knee magnetic resonance imaging. The torsion values of the femur and tibia were independently measured using the Waidelich and Strecker method. Knee version, defined as static rotation of the tibia with respect to the femur in full extension, was determined by measuring the angle between the tangent lines to the dorsal femoral condyle (DFC) and the dorsal tibial head (DTH; defined by the posterior point of the proximal tibial plateau). Supplementary measurements were obtained as follows: (1) femoral epicondylar line (FEL), (2) tibial ellipse center line (TECL), (3) tibial tuberosity-trochlear groove (TT-TG) distance, and (4) tibial tuberosity-posterior cruciate ligament (TT-PCL) distance.

RESULTS

In 200 analyzed legs of 100 volunteers (mean age, 26.5 ± 5.8 years [range, 18 to 40 years]), we identified a mean internal femoral torsion of -23.8°± 9.7° (range, -46.2° to 1.6°), external tibial torsion of 33.2°± 7.4° (range, 16.4° to 50.3°), and external knee version (DFC to DTH) of 1.3°± 3.9° (range, -8.7° to 11.7°). Other measurements were as follows: FEL to TECL, -0.9°± 4.9° (range, -16.8° to 12.1°); FEL to DTH, -3.6°± 4.0° (range, -12.6° to 6.8°); and DFC to TECL, 4.0°± 4.9° (range, -12.7° to 14.7°). The mean TT-TG distance was 13.4 ± 3.7 mm (range, 5.3-23.5 mm), and the mean TT-PCL distance was 11.5 ± 3.5 mm (range, 6.0-20.9 mm). Female participants had significantly greater external knee version than male participants.

CONCLUSION

Coronal- and sagittal-plane alignments of the knee have a well-known effect on the biomechanics of this joint. Additional information about the axial plane may result in new decision-making algorithms for managing knee disorders. This study is the first to report standard values of knee version in a healthy population. As a subsequent step building on this work, we advocate for the measurement of knee version in patients with patellofemoral disorders, as this parameter may assist with new treatment guidelines in the future.

What is the Incidence of Subsequent Adjacent Joint Injury After Patellofemoral Pain?

OBJECTIVE

To investigate the incidence of subsequent lumbar spine, hip, and ankle-foot injuries after a diagnosis of patellofemoral pain.

DESIGN

Retrospective cohort study.

SETTING

Military Health System.

PARTICIPANTS

Individuals (n = 92,319) ages 17-60 diagnosed with patellofemoral pain between 2010-2011.

INTERVENTIONS

Therapeutic exercise.

MAIN OUTCOME MEASURES

Frequency of adjacent joint injuries in the 2-year period after initial patellofemoral pain injury, and hazard ratios (HR) with 95% confidence interval (CI) and Kaplan-Meier survival curves for risk of adjacent joint injury based on receiving therapeutic exercise for the initial injury.

RESULTS

After initial patellofemoral pain diagnosis, 42,983 (46.6%) individuals sought care for an adjacent joint injury. Of these, 19,587 (21.2%) were subsequently diagnosed with a lumbar injury, 2837 (3.1%) a hip injury, and 10,166 (11.0%) an ankle-foot injury. One in five (19.5%; n = 17,966) received therapeutic exercise which reduced the risk of having a subsequent lumbar (HR = 0.78, 95% CI 0.76-0.81), hip (HR = 0.93, 95% CI 0.87-0.98) or ankle-foot (HR = 0.86, 95% CI 0.83-0.90) injury.

CONCLUSION

The results suggest that a high number of individuals with patellofemoral pain will sustain an adjacent joint injury within 2 years although causal relationships cannot be determined. Receiving therapeutic exercise for the initial knee injury reduced the risk of sustaining an adjacent joint injury. This study helps provide normative data for subsequent injury rates in this population and guide development of future studies designed to understand causal factors.

The Effects of Increasing Trunk Flexion During Stair Ascent on the Rate and Magnitude of Achilles Tendon Force in Asymptomatic Females

Research indicates that increasing trunk flexion may optimize patellofemoral joint loading. However, this postural change could cause an excessive Achilles tendon force (ATF) and injury risk during movement. This study aimed to examine the effects of increasing trunk flexion during stair ascent on ATF, ankle biomechanics, and vertical ground reaction force in females. Twenty asymptomatic females (age: 23.4 [2.5] y; height: 1.6 [0.8] m; mass: 63.0 [12.2] kg) ascended stairs using their self-selected and flexed trunk postures. Compared with the self-selected trunk condition, decreases were observed for peak ATF (mean differences [MD] = 0.14 N/kg; 95% confidence interval [CI], 0.06 to 0.23; Cohen d = -1.2; P = .003), average rate of ATF development (MD = 0.25 N/kg/s; 95% CI, 0.07 to 0.43; Cohen d = -0.9; P = .010), ankle plantar flexion moment (MD = 0.08 N·m/kg; 95% CI, 0.03 to 0.13; Cohen d = -1.1; P = .005), and vertical ground reaction force (MD = 38.6 N/kg; 95% CI, 20.3 to 56.90; Cohen d = -1.8; P < .001). Increasing trunk flexion did not increase ATF. Instead, this postural change was associated with a decreased ATF rate and magnitude and may benefit individuals with painful Achilles tendinopathy.

Signs of Nervous System Sensitization in Female Runners with Chronic Patellofemoral Pain

Background

Patellofemoral pain (PFP) is a common overuse injury among runners, affecting females at a higher rate than males. PFP can often become chronic, with evidence suggesting it may be linked to both peripheral and central sensitization of the nervous system. Sensitization of the nervous system can be identified through quantitative sensory testing (QST).

Hypothesis/Purpose

The primary objective of this pilot study was to quantify and compare pain sensitivity as identified through QST measures, in active female runners with and without PFP.

Study Design

Cohort Study.

Methods

Twenty healthy female runners and 17 female runners with chronic PFP symptoms were enrolled. Subjects completed the Knee injury and Osteoarthritis Outcome Score for Patellofemoral Pain (KOOS-PF), University of Wisconsin Running Injury and Recovery Index (UWRI), and the Brief Pain Inventory (BPI). QST consisted of pressure pain threshold testing to three local and three distant sites to the knee, heat temporal summation, heat pain threshold, and conditioned pain modulation. Data was analyzed utilizing independent t-tests for comparison of between-group data, effect sizes for QST measures (Pearson's r), and Pearson's correlation coefficient between pressure pain threshold values at the knee and functional testing.

Results

The PFP group exhibited significantly lower scores on the KOOS-PF (p<0.001), BPI Pain Severity and Interference Scores (p<0.001), and UWRI (p<0.001). Primary hyperalgesia, identified through decreased pressure pain threshold at the knee, was detected in the PFP group at the central patella (p<0.001), lateral patellar retinaculum (p=0.003), and patellar tendon (p=0.006). Secondary hyperalgesia, a sign of central sensitization, was observed via differences in pressure pain threshold testing for the PFP group at the uninvolved knee (p=0.012 to p=0.042), involved extremity remote sites (p=0.001 to p=0.006), and uninvolved extremity remote sites (p=0.013 to p=0.021).

Conclusion

Compared to healthy controls, female runners with chronic PFP symptoms exhibit signs of both peripheral sensitization. Despite actively participating in running, nervous system sensitization may contribute to continued pain in these individuals. For female runners with chronic PFP, physical therapy management may need to include interventions which address signs of central and peripheral sensitization.

Level of Evidence

Level 3.

Effects of taping in patellofemoral pain syndrome: A systematic review

BACKGROUND

Patellofemoral pain syndrome (PPS) is defined as a condition in the patellofemoral joint that can present with pain, functional deficit, crepitus, and instability. Its etiology appears to lie in excessive loading of the patellofemoral joint due to mispositioning of the patella. The application of taping has recently increased, to manage PPS. However, the level of scientific evidence in this sense is unknown.

OBJECTIVE

To determine the effect of different types of taping in subjects with PPS.

METHODS

A bibliographic search was carried out in January and February 2021 in Scopus, Web of Science, PubMed, Medline, SPORTDiscus, PEDro and CINAHL.

RESULTS

A total of 13 studies were included for qualitative analysis. The mean score on the PEDro scale was 5.30 points. Most of the articles reflect a decrease in pain after the taping intervention, while variables such as functionality, muscle activity and biomechanical modification do not show positive effects.

CONCLUSION

Taping appears to have positive effects on pain in subjects with PPS. However, the evidence is contradictory with the rest of the variables studied.

Strength Training Rehabilitation Incorporating Power Exercises (STRIPE) for individuals with patellofemoral pain: a randomised controlled trial protocol

Patellofemoral pain (PFP) is a chronic condition that presents with patellar pain during various daily and recreational activities. Individuals with PFP have a wide range of impairments that result in long-term disability and reduced quality of life. Current interventions target hip muscle weakness with strength-based exercises, but recurrence rates are as high as 90%. A single feasibility study demonstrated success with power-based exercises; however, there is limited evidence evaluating pain or self-reported function in larger cohorts, and no study has assessed recurrence rates. This protocol details a study evaluating a strength-based rehabilitation programme compared with a strength-based programme incorporating power-based exercises in individuals with PFP. This single-blinded randomised controlled trial will evaluate 88 participants with PFP, aged 18-40 years old. Participants will be recruited from three universities, the surrounding community and sports medicine clinics. Participants will receive three telemedicine rehabilitation sessions a week for 6 weeks. The rehabilitation programme will consist of either strength-based exercises or a combination of power and strength-based exercises. Pain, subjective function and recurrence rates will be assessed at baseline, immediately after the intervention and at four follow-up time points: 6-month, 12-month, 18-month and 24-month postintervention. We will also assess neuromuscular function of the hips and global rating of change at each postintervention time point. Trial registration number NCT05403944.

Frontal plane projection angle predicts patellofemoral pain: Prospective study in male military cadets

BACKGROUND

Patellofemoral pain (PFP) is a major source of knee pain. Identifying who may develop PFP is of paramount importance.

PURPOSE

To assess whether Frontal plane projection angles (FPPA) and hand held dynamometry (HHD) strength measures can predict development of PFP.

STUDY DESIGN

Prospective evaluation of individuals undertaking a military training programme.

METHODS

Male military recruits were enrolled and prospectively followed up from enrolment to completion of 12-weeks training. Lower limb kinematics (FPPA, Q-angle, hip adduction angle, knee flexion, ankle dorsiflexion, and rearfoot eversion angle) measured during running, single leg squatting (SLS), and single leg landing (SLL) and isometric muscle strength of hip abductors and knee extensors.

RESULTS

Body mass, hip abductor muscle strength, Q-angle during SLS and SLL, FPPA during SLL all significantly different between the PFP and non-injured groups and predicted PFP, highest predictor variable was FPPA during SLL (Odds Ratio = 1.13, P = 0.01). A FPPA≥5.2° during SLL predicting PFP with a sensitivity of 70% and a specificity of 70%.

CONCLUSION

Participants who developed PFP had a number of physical factors significantly different than the non-injured group, most predictive was a larger FPPA during SLL, with angles greater than 5.2° associated with a 2.2x greater risk.

CLINICAL RELEVANCE

Assessing FPPA during SLL could be used to determine who was predisposed to PFP.

Are Physical Function and Fear of Movement Risk Factors for Patellofemoral Pain? A 2-Year Prospective Study

CONTEXT

To determine (1) whether physical function and fear of movement are prospectively associated with the risk of females developing patellofemoral pain (PFP) and (2) whether they change following development of PFP.

DESIGN

Prospective observational study.

METHODS

A total of 114 asymptomatic females (18-22 y old) completed assessment of physical function (forward step-down test and single-leg hop for distance) and fear of movement using the Tampa Scale for Kinesiophobia at baseline and 2-year follow-up. Presence of symptoms of PFP was monitored bimonthly.

RESULTS

Ninety participants (retention rate = 79%) completed the 2-year follow-up assessment, with 27 (24% of the cohort) developing PFP. Physical function, including forward step-down test (P = .659) and single-leg hop for distance (P = .825), and fear of movement (P = .479) were not associated with the risk of developing PFP. Females who developed PFP presented with reduced forward step-down repetitions (mean difference = 2.8; 95% confidence interval, 0.2 to 5.3) and single-leg hop for distance (10.2; 95% confidence interval, 2.7 to 17.7 cm) at 2-year follow-up. There was no statistically significant difference between those who did and did not develop PFP for fear of movement (-3.4; 95% confidence interval, -7.0 to 0.2).

CONCLUSIONS

Physical function and fear of movement were not associated with the risk of developing PFP in young females. However, the change over time in the step-down and single-leg hop for distance tests may suggest that, even in the early stages of PFP, young females present impaired physical function compared with females who did not develop symptoms. Fear of movement may develop due to persistent PFP, and does not appear to be a risk factor or key feature in females with PFP of short symptoms duration.

Improvement of Pain and Function by Using Botulinum Toxin Type A Injection in Patients with an Osteoarthritic Knee with Patellar Malalignment: An Electromyographic Study

Objective: To determine the pain and electromyographic (EMG) amplitude ratio of the vastus medialis oblique (VMO) to the vastus lateralis (VL) after botulinum toxin type A (BTA) was injected in the bilateral osteoarthritic knee of patients with patellar malalignment for analysis. Material and methods: A total of fifteen patients were recruited; the more symptomatic knee of each patient received a BTA injection (BTA side). The other set of patients were left untreated. In all, fifteen healthy participants comprised the control group. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and numeric rating scale (NRS) for pain were assessed. The EMG amplitude of VL and VMO activity was recorded using an isokinetic dynamometer and synchronized using the BIOPAC MP100. The data were collected before and at 4, 8, and 12 weeks post−BTA injection. Results: The EMG ratios of the patient group were lower than those of the control group at all testing velocities (p < 0.05). The VMO/VL ratio improved significantly on the BTA side only. The VMO/VL ratios on the BTA side were higher than those on the untreated side (p < 0.05). Knee pain decreased significantly after the BTA injection. The EMG ratios were negatively correlated with the NRS and WOMAC scores. Conclusion: BTA injection effectively reduces knee pain and restores the EMG ratio between the VMO and VL.

An Updated Model Does Not Reveal Sex Differences in Patellofemoral Joint Stress during Running

Background

Structure-specific loading may have implications in understanding the mechanisms of running related injury. As females demonstrate a prevalence of patellofemoral pain twice that of males, this may indicate differences in patellofemoral loads between males and females. Previous works investigating differences in patellofemoral joint stress have shown conflicting results, but the models employed have not used estimates of muscle forces or sex specific contact areas.

Hypothesis/Purpose

The aim of this study was to examine sex differences in patellofemoral joint stress using an updated model to include estimates of quadriceps muscle force and sex-specific patellofemoral contact area.

Study Design

Descriptive Laboratory Study.

Methods

Forty-five healthy recreational runners ran at a controlled speed down a 20-meter runway. Kinetic and kinematic data were utilized to estimate muscle forces using static optimization. Quadriceps muscle force was utilized with sex-specific patellofemoral joint contact area in a two-dimensional patellofemoral joint model to estimate patellofemoral joint stress. Multivariate tests were utilized to detect sex differences in patellofemoral loading and hip and knee kinematics.

Results

No differences were found between sexes in measures of patellofemoral loading or quadriceps force. Females displayed a reduced knee extension moment and greater hip adduction and internal rotation than males.

Conclusion

The inclusion of static optimization to estimate quadriceps muscle force and sex-specific contact area of the patellofemoral joint did not reveal sex differences in patellofemoral joint stress, but differences in non-sagittal plane hip motion were detected. Therefore, two-dimensional patellofemoral models may not fully characterize differences in patellofemoral joint stress between males and females. Three-dimensional patellofemoral models may be necessary to determine if sex differences in patellofemoral joint stress exist.

Level of Evidence

3b.

The influence of iliotibial tract thickness on clinical outcomes in women with patellofemoral pain

BACKGROUND

The assessment of iliotibial tract thickness by ultrasonography may help identify a key, previously unexplored factor that may contribute directly to the homeostasis imbalance of the femoropatellar joint in people with patellofemoral pain (PFP).

OBJECTIVES

To compare the iliotibial tract thickness of people with PFP and asymptomatic people; and to correlate the iliotibial tract thickness with self-reported pain and function of people with PFP.

METHODS

Eighty women, separated into two groups: PFP group (n = 40) and control group consisting of asymptomatic participants (CG; n = 40). The participants answered the Anterior Knee Pain Scale (AKPS) questionnaire, to identify the self-reported knee function; they evaluated the pain in millimeters by the Visual Analog Scale for pain (VAS). For the imaging evaluation, an ultrasound was used, with a linear transducer at the distal portion of the iliotibial tract (coronal plane), with the participants positioned in dorsal decubitus, with 20° of knee flexion. The iliotibial band was visualized in its long axis, and three sequential images were recorded between the lateral femoral condyle and the lateral tibial condyle. The measurements were normalized and correlated.

RESULTS

The groups had no differences (P > 0.001) between participants for: age/weight/height/IMC. Participants in the PFP group had moderate levels of pain (58 + 2.1 mm), considerable self-reported functional limitation (d = 3.05) and greater iliotibial tract thickness compared with the CG (d = 2.41).

CONCLUSION

The iliotibial tract of women diagnosed with PFP have greater thickness compared with asymptomatic women. There was no association between iliotibial tract thickness and subjective measures of pain and function.

Epidemiology of Musculoskeletal Injuries in the Navy: A Systematic Review

Objectives: This study aimed to critically review the results of recent studies that investigated the epidemiology of noncombat-related musculoskeletal injuries (MSIs) in the Navy. Methods: A systematic search was conducted of three major databases (Pubmed, Embase, and Cochrane) to identify epidemiological studies on MSIs in the Navy. Study selection and risk of bias assessment were conducted. Results: The overall prevalence of MSIs ranged from 12.69% to 48.81%. And the prevalence of head and face injuries, upper extremity injuries, spine injuries, chest injuries, and lower extremity injuries were 0.11%-0.66%, 0.53%-11.47%, 0.75%-12.09%, 0.43%-0.95%, and 0.4%-21.17%, respectively. For the specific MSIs, the incidence ranged from 0.03/1000 person-years to 32.3/1000 person-years in the Navy and Marines. The ankle-foot, lumbopelvic, knee and lower leg, and shoulder were identified as the most frequent location for MSIs. Conclusion: This systematic review summarized that the Navy population had a high prevalence of MSIs. And different risk factors for MSIs varied from different anatomic locations. This systematic review also provided valuable information on MSIs for sports medicine specialists.

The relationship between ankle dorsiflexion range of motion, frontal plane projection angle, and patellofemoral pain syndrome

BACKGROUND

Ankle range of motion abnormalities have been often linked with alteration in knee kinematics leading to the development of patellofemoral pain syndrome (PFPS). Literature exploring the relationship between ankle dorsiflexion range of motion (DF ROM) and knee kinematics during functional tasks is scanty. This study aims to assess the relation between ankle DF ROM and frontal plane projection angle (FPPA), one of the knee kinematic variables, in individuals with and without PFPS during a step-down test.

METHODS

This is a case-control study in which seventy PFPS patients and other 70 asymptomatic control subjects had their ankle DF ROM measured using an inclinometer with the knee flexed and extended. Their FPPA angles were measured using Kinovea software while doing the step-down test.

RESULTS

When the two groups were compared, ankle DF ROM measured with the knee flexed was higher in the control group (33.15 ± 4.96) than in the PFPS group (30.20 ± 6.93) (p = 0.03). In both the PFPS group and the control group, the correlation between FPPA and ankle DF ROM with the knee flexed was statistically insignificant (p = 0.075 and 0.323 respectively).

CONCLUSION

Decreased ankle DF ROM can be one of the contributing factors to the development of PFPS in the context of greater dynamic knee valgus.

Computational biomechanics of human knee joint in stair ascent: Muscle-ligament-contact forces and comparison with level walking

About a third of knee joint disorders originate from the patellofemoral (PF) site that makes stair ascent a difficult activity for patients. A detailed finite element model of the knee joint is coupled to a lower extremity musculoskeletal model to simulate the stance phase of stair ascent. It is driven by the mean of measurements on the hip-knee-ankle moments-angles as well as ground reaction forces reported in healthy individuals. Predicted muscle activities compare well to the recorded electromyography data. Peak forces in quadriceps (3.87 BW, body weight, at 20% instance in our 607 N subject), medial hamstrings (0.77 BW at 20%), and gastrocnemii (1.21 BW at 80%) are estimated. Due to much greater flexion angles-moments in the first half of stance, large PF contact forces (peak of 3.1 BW at 20% stance) and stresses (peak of 4.83 MPa at 20% stance) are estimated that exceed their peaks in level walking by fourfold and twofold, respectively. Compared with level walking, ACL forces diminish in the first half of stance but substantially increase later in the second half (peak of 0.76 BW at 75% stance). Under nearly similar contact forces at 20% of stance, the contact stress on the tibiofemoral (TF) medial plateau reaches a peak (9.68 MPa) twice that on the PF joint suggesting the vulnerability of both joints. Compared with walking, stair ascent increases peak ACL force and both peak TF and PF contact stresses. Reductions in the knee flexion moment and/or angle appear as a viable strategy to mitigate internal loads and pain.

Functional Outcomes, Survival Rate, and Complications of Patellofemoral Arthroplasty: Mid-Term Results From Independent Center

Background Patellofemoral arthroplasty (PFA) is indicated for isolated patellofemoral arthritis. PFA is a less invasive, bone-preserving procedure with faster recovery when compared to total knee replacement. We aim to present the functional outcome, survival rate, and complications of PFA from our center. Methods A total of 45 consecutive PFA performed (mean age 58.02 ± 9.2 years; 34 females and 11 males; Avon prosthesis) during the study period was included. Prosthesis survivorship was measured using revision as the endpoint, and functional outcome was assessed using Oxford knee scores (OKSs), EQ-5D, and satisfaction scores. Postoperative complications, the number of revisions, and the reasons causing them were collected. Results The mean follow-up was 48.7 (range 16-66) months. As compared to preoperative scores, OKS and Eq5d showed significant improvements (p<0.001). The satisfaction scores indicated that 28 patients (62%) were very satisfied, 10 (26.7%) were satisfied, and seven (15.5%) were dissatisfied. Four patients (8.9%) underwent revision surgery with a total knee replacement. Out of four patients requiring revision, two had progressive arthritis of the medial compartment, one had aseptic loosening of the implants, and one had trauma. Five patients showed persistent anteromedial knee pain (12.2%); one patient had maltracking requiring lateral release; one patient developed stiffness with knee flexion less than 60 degrees requiring manipulation under anesthesia. Conclusion Our results indicated that good or excellent functional outcomes can be expected in >80% of patients with survivorship of 91.1% at mid-term. Careful patient selection and counseling should be done informing of the risk of dissatisfaction/persistent pain and revision surgery in the mid and long term. Long-term outcomes and factors determining good outcomes need to be evaluated in future research.