Vastus medialis obliquus atrophy: does it exist in patellofemoral pain syndrome?

Developing a Multi-Directional Lower-Limb Training System Toward Aging in Place Rehabilitation: A Preliminary Feasibility Study on Healthy Individuals

Not only improving muscle strength but also improving muscle power and neuromuscular control are important factors in improving lower limb function. In this study, a multi-directional lower-limb training system for aging -in-place rehabilitation was developed. The training system offers four distinct modes: muscle power training, pivoting neuromuscular training, muscle strength training using eccentric contractions, and proprioception training with evaluation. The feasibility of the training system was assessed through experiments conducted on healthy adults. Parameters such as mean of electromyography (EMG) peaks and pivoting instability during stepping tasks, and proprioceptive acuity in terms of pivoting angle error were tested using the system. By incorporating these diverse training modes, the training system can potentially be used to support clinicians in delivering tailored and effective subject-specific interventions for individuals with musculoskeletal and/or neuromuscular abnormalities toward aging-in-place rehabilitation.

Patellofemoral Pain Syndrome: Focused Vibrations Plus Kinesiotaping with Insights into Radiological Influences-An Observational Study

BACKGROUND

This observational study investigates the efficacy of combining local muscle vibration (LMV) therapy and kinesiotaping using the McConnell method (KMcCM) in patients with patellofemoral pain syndrome (PFPS). PFPS is a prevalent knee condition characterized by anterior or medial knee pain exacerbated by activities that overload the patellofemoral joint.

OBJECTIVE

The primary aim of this study was to evaluate the effectiveness of LMV combined with KMcCM in reducing pain and improving function in PFPS patients.

METHODS

A total of 52 participants, aged 25-85, with PFPS were included. Participants underwent LMV and KMcCM treatments three times weekly for three weeks. Pain and function were assessed using the Visual Analog Scale (VAS) and the Knee Injury and Osteoarthritis Outcome Score (KOOS) at baseline (T0) and six months post-treatment (T1). Radiological assessments of patellar alignment and biomechanics were also conducted through dynamic MRI.

RESULTS

Significant pain reduction and functional improvements were observed across all age groups. Notably, younger participants showed greater improvement compared to older participants. Among women, those in the younger age group experienced more substantial reductions in VAS scores compared to their older counterparts. KOOS scores improved significantly, indicating enhanced knee function overall. A significant decrease in VAS scores from T0 to T1 was observed across all patellar alignment groups, signifying a reduction in pain levels. However, Group 2 (Laxation and Subluxation) experienced the most substantial reduction in VAS scores at T1 compared to the other groups. These results suggest that the combination of LMV and KMcCM may be particularly effective in addressing biomechanical abnormalities associated with patellar maltracking and enhancing VMO muscle contraction, leading to more substantial improvements in these patients.

CONCLUSIONS

The combination of LMV and KMcCM demonstrates promising efficacy in reducing pain and improving knee function in PFPS patients, with age and gender influencing treatment outcomes. The most significant improvements were observed in younger individuals and those with specific patellar alignment issues, highlighting the potential of this combined approach for the targeted treatment of PFPS.

Assessment of Quadriceps Muscle in Advanced Knee Osteoarthritis and Correlation with Lower Limb Alignment

Background and Objectives: Despite extensive studies of the role of quadriceps and quadriceps/hamstring balance in knee osteoarthritis (OA), the roles of the vastus intermedius, medialis, and lateralis in OA remain unclear. The purpose of this study was to investigate the relationship of lower limb alignment and the ratio of the quadriceps femoris muscle to the knee extensor muscle. Materials and Methods: This study included 50 patients with advanced knee OA (Kellgren/Lawrence grade of 3 or 4) and 25 healthy control persons between June 2021 and May 2022. The osteoarthritis grade and anatomical tibiofemoral angle were measured based on plain radiography and scanography. All participants were divided into normal (0~5°), mild varus (5°~10°), and severe varus (>10°) groups. Using MRI, muscle size was determined by calculating the cross-sectional area (CSA) of the total quadriceps (rectus femoris, vastus intermedius, vastus medialis, and vastus lateralis) and its components. Results: The CSA ratio of the vastus lateralis was significantly smaller in the severe varus group than in the normal or mild varus groups. There was a significant positive correlation between the mechanical tibiofemoral angle and vastus lateralis CSA (ρ = 0.282, p = 0.014) and between the anatomical tibiofemoral angle and vastus lateralis CSA (ρ = 0.294, p = 0.011). There was a significant negative correlation between the mechanical tibiofemoral angle and vastus intermedius CSA (ρ = -0.263, p = 0.023) and between the anatomical tibiofemoral angle and vastus intermedius CSA (ρ = -0.243, p = 0.036). Conclusions: Patients with severe varus alignment exhibited vastus lateralis atrophy. This study highlights vastus lateralis atrophy in severe varus alignment, though causality between atrophy and varus knee OA remains uncertain. We think that patients with severe varus may require strengthening exercises focused on the vastus lateralis before and after surgery for alignment correction.

Contribution of Shockwave Therapy in the Functional Rehabilitation Program of Patients with Patellofemoral Pain Syndrome

Background: Patellofemoral pain syndrome is a condition with an increasing incidence in recent years, being known as the most common cause of knee pain in adults and adolescents. Undiagnosed and untreated, this condition can worsen over time. The aggravation leads to an increase in the intensity of the pain and the risk of injury, along with an increase in stress on the other joints of the lower limb. The objective of this study was to evaluate the contribution of shockwave therapy to a functional rehabilitation programme for patients with patellofemoral pain syndrome. Materials and Methods: The study was carried out on a group of 64 subjects (32 males and 32 females), aged between 20 and 39 years. The subjects were divided into two groups: 32 subjects who followed a program of functional rehabilitation based on low- and medium-frequency electrotherapy, ultrasound and laser therapy, along with a physical therapy program lasting approximately 3 weeks, and 32 subjects who followed a functional rehabilitation program based on shockwave therapy and specific physical therapy exercises lasting approximately 3 weeks. Results: Following the protocols applied to the two groups, the pain reported by the patients decreased, while the functional parameters of the knee improved, better results being obtained in the group that performed shock wave therapy together with specific physical therapy programs (Cohen Index 5916, p < 0.001). Conclusions: This study indicates that radial shockwave therapy combined with physiotherapy may provide additional benefits for patellofemoral syndrome, including greater pain reduction and improved joint mobility, compared to traditional treatments. However, further research is needed to confirm these findings and their broader clinical applicability.

The vastus medialis oblique compensates in current patellar dislocation patients with the increased femoral anteversion

PURPOSE

The purpose of this study was to investigate whether the vastus medialis oblique (VMO) muscle compensates in patellar dislocation (PD) patients with the increased femoral anteversion angle (FAA).

METHODS

Between 2021 and 2024, we included 60 patients with recurrent PD (RPD group). Inclusion criteria were at least two episodes of PD, as well as complete CT scans of the knee and hip. Exclusion criteria included traumatic or habitual dislocation, previous knee surgery, etc. Of these patients, 30 with excessive FAA (≥ 30°) were assigned to the A group, and 30 without excessive FAA (< 30°) to the B group. A control group of 120 patients without patellofemoral disorders was also included (C group). The cross-sectional areas of the VMO and vastus lateralis muscle (VLM) were measured 20 mm above the patella on CT scans, and the VMO/VLM area ratio was calculated. The correlation between FAA and the VMO/VLM ratio was analyzed.

RESULTS

The RPD group had a significantly larger FAA (15.0 ± 1.9° vs. 30.1 ± 9.6°, P = 0.040) and a smaller VMO/VLM ratio (4.2 ± 1.5 vs. 3.5 ± 1.0, P = 0.014) compared to the C group. Within the RPD group, the A group had a higher VMO/VLM ratio than the B group (4.0 ± 1.1 vs. 3.0 ± 0.7, P = 0.029). The B group's VMO/VLM ratio was lower than that of the C group (3.0 ± 0.7 vs. 4.2 ± 1.5, P = 0.004). However, there was no significant difference in the VMO/VLM ratio between the A group and the C group. The VMO/VLM ratio showed a moderate positive correlation with FAA in the RPD group, with a correlation coefficient of r = 0.4 (P = 0.012), indicating a statistically significant relationship between the two.

CONCLUSION

Patients with recurrent PD showed a smaller VMO/VLM ratio compared to controls. Increased FAA was correlated with compensatory thickening of the VMO and a higher VMO/VLM ratio in PD patients. This suggests that increased FAA may drive biomechanical adaptations in the quadriceps, stabilizing the patella. Clinicians should consider changes in FAA when assessing and treating PD.

LEVEL OF EVIDENCE

Level III.

Lower Extremity Muscle Volume in Unilateral and Bilateral Patellofemoral Pain: A Cross-Sectional Exploratory Study Including Superficial and Deep Muscles

CONTEXT

Existing patellofemoral pain (PFP) literature has primarily been focused on quadriceps muscle volume, with limited attention given to the deep and superficial muscle volume of the lower limbs in individuals with unilateral and bilateral PFP. In this paper, we aim to fill this gap.

OBJECTIVE

To explore superficial and deep lower extremity muscle volume in women with unilateral or bilateral PFP compared with a normative database of pain-free women.

DESIGN

Cross-sectional study.

SETTING

University imaging research center.

PATIENTS OR OTHER PARTICIPANTS

Twenty women with PFP (10 unilateral and 10 bilateral) and 8 pain-free women from a normative database.

MAIN OUTCOME MEASURE(S)

We quantified lower extremity muscle volume via 3.0-T magnetic resonance imaging. Two separate 1-way analyses of variance were performed: (1) unilateral PFP (painful versus nonpainful limb) versus pain-free control groups and (2) bilateral PFP (more painful versus less painful limb) versus pain-free control groups.

RESULTS

We observed no differences in age and body mass index across groups (P > .05). Compared with the pain-free group, the unilateral and bilateral PFP groups had bilaterally smaller volumes of the anterior (iliacus: P ≤ .0004; d range, 2.12-2.65), medial (adductor brevis, adductor longus, gracilis, and pectineus: P ≤ .02; d range, 1.25-2.48), posterior (obturator externus, obturator internus, and quadratus femoris: P < .05; d range, 1.17-4.82), and lateral (gluteus minimus: P ≤ .03; d range, 1.16-2.09) hip muscles and knee extensors (rectus femoris: P ≤ .003; d range, 1.67-2.16) and flexors (long and short head of the biceps femoris: P ≤ .01, d range, 1.56-1.93).

CONCLUSIONS

Women with unilateral and those with bilateral PFP displayed less volume of multiple superficial and deep muscles of the bilateral hips and knees than pain-free women. Interventions should bilaterally target lower limb muscles when treating PFP, and hypertrophy exercises for specific muscles should be explored to increase choices for intervention.

Evaluation of the results of closed kinetic chain exercises applied in the conservative treatment of patellofemoral pain syndrome by means of shear wave elastography: A randomized controlled trial

PURPOSE

Non-selective closed kinetic chain exercises (NSKCE) and or selective closed kinetic chain exercises (SCKCE) has been shown to increase Vastus medialis obliquus (VMO) muscle power in patellofemoral pain syndrome (PFPS). However, the superiority of the exercises to each other has not been shown. This study aimed to evaluating the effects of different exercises on the stiffness of the VMO and vastus lateralis (VL) muscles, pain management, functional scores, and thigh circumferences.

METHODS

One hundred 60 knees of 80 patients followed up in our outpatient clinic between December 2016 and February 2018 were included in the study. Patients were divided into two groups as 40 patients with single-sided PFPS (20 male and 20 female patients) and 40 healthy controls (20 male and 20 female patients). The patients in each group were divided into subgroups according to NSCKCE or SCKCE. VMO and VL muscles were measured by shear wave elastography (SWE) before and after a 6-weeks therapy.

RESULTS

There was a significant decrease in Visual Analog Scale (VAS) score while a significant increase was found in Lysholm Knee Scale (LKS), however, no statistically difference was found between the two exercise groups in PFPS patients. The effect of both exercises on pain and functional improvement was similar.

CONCLUSION

Decrease in VAS scores, increase in LKS scores, increase in thigh circumference measurements, and increase in the stiffness of VMO and VL muscles were observed in both groups who received SCKCE and NSCKCE on PFPS patients.

TRIAL REGISTRATION

Study registered at ClinicalTrials.gov (registration number: NCT05427357).

DESIGN

Randomized controlled trial.

Role of kinetic chain in sports performance and injury risk: a narrative review

The kinetic chain refers to the body's intricate coordination of various segments to perform a specific activity involving precise positioning, timing, and speed. This process is based on task-oriented and activity-specific pre-programmed muscle activation patterns enhanced by repeated practice. It demands muscular eccentric strength, joint flexibility, and musculotendinous elastic energy storage. The body core (lumbopelvic-hip complex) forms the kinetic chains' central point of activities in most sports because it facilitates load transfers to and from the limbs. The kinetic chain relationship with fascia, peripheral nerves, and tensegrity is fundamental to holistic human body movements. The kinetic chain function demands neuromuscular, sensorimotor, and neurocognitive control. Any blockage or defect in the kinetic chain can develop compensatory patterns, high demands on distal parts, and overuse and overload injuries. Taking a holistic approach and evaluating the integrity of the kinetic chain in athletes can significantly enhance efforts to improve sports performance and mitigate injury risk.

Does Restricted Ankle Joint Mobility Influence Hamstring Muscle Strength, Work and Power in Football Players after ACL Reconstruction and Non-Injured Players?

This study was aimed at observing how the limitation of ankle dorsiflexion ROM affects hamstring muscle Peak Torque/BW (%), Average Power (W), and Total Work (J), and whether this effect is similar in football players after ACL rupture and reconstruction and in those without injuries. The study included 47 professional football players who were divided into two groups: Group 1 (n = 24) after ACL reconstruction and Group 2 (n = 23) without injuries in the past 3 years. Based on the Weight-Bearing Lunge Test (WBLT), the following subgroups in Groups 1 and 2 were distinguished: N (normal ankle joint dorsiflexion) and R (restricted ankle joint dorsiflexion). The concentric isokinetic test (10 knee flexions and extensions at 60°/s) was performed on both limbs. Significantly lower values of Peak Torque/BW and Average Power were observed in Group 1 compared to Group 2, as well as in subjects with normal and restricted ankle dorsiflexion. However, no significant differences were noted for either group in any of the strength variables comparing subjects with normal and restricted ankle dorsiflexion. A poor and non-significant correlation was exhibited between the ankle joint range of dorsiflexion and all the strength variables. The area under the ROC curve (AUC) for all the evaluated variables in both groups was below 0.5, or very close to this value, indicating that ankle dorsiflexion ROM has no diagnostic accuracy for hamstring muscle strength. Based on the obtained results, it can be assumed that ankle dorsiflexion limitation, which is common in football players, is not a factor in weakening hamstring muscle strength, either in football players after ACL reconstruction or among those without injuries. However, some authors have reported that limited mobility of the ankle joint can have a destructive effect on the work of the lower limbs and may also be a factor in increasing the risk of football injuries in this area. Therefore, we have suggested that hamstring muscle weakness and increased risk of injury may occur due to factors other than limited ankle mobility. These observations may be of great importance in the selection of prevention methods by including a broad spectrum of physical techniques, not just exercises that focus on the improvement of mobility or stability of the lower limbs.

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.

Correlation of ankle dorsiflexion range of motion with lower-limb kinetic chain function and hop test performance in healthy male recreational athletes

Background

The study aims to identify the correlation of ankle dorsiflexion range-of-motion (ADROM) (with its related gastrocnemius and soleus extensibility) with lower-limb kinetic chain function and hop test performance in young healthy recreational athletes.

Methods

Twenty-one young male healthy recreational athletes were tested for ADROM, gastrocnemius and soleus extensibility, lower-limb kinetic chain function with the closed kinetic chain lower extremity stability test (CKCLEST) and hop test performance with the single-leg hop for distance test (SHDT) and side hop test (SHT).

Results

There was a positive significant (rho = 0.514, 95% CI [0.092-0.779], P < 0.01) correlation between the dominant lower-limb weight-bearing/closed-chain ADROM (that represented the soleus extensibility) and the CKCLEST. There were no significant correlations between the study performance-based tests and open-chain ADROM (P > 0.05).

Conclusion

The CKCLEST is positively and significantly correlated with SHT and weight-bearing ADROM with knee flexion (and its related soleus extensibility) which suggests comparability among them. Open-chain ADROM has a negligible and non-significant correlation with the readings of this study performance-based tests suggesting that it is probably not an essential construct of their execution. To the best of our knowledge, this study is the first to investigate these correlations.

Periarticular muscle status affects in vivo tibio-femoral joint loads after total knee arthroplasty

Background: Total knee arthroplasty (TKA) is a highly effective treatment for severe knee osteoarthritis that is increasingly performed in younger, more active patients. As postoperative muscular impairments may negatively affect surgical outcomes and implant longevity, functional muscle recovery gains increasing importance in meeting future patient demands. This study aimed to assess the status of periarticular muscles in the long-term follow-up after TKA and to evaluate its impact on in vivo tibio-femoral joint loads. Methods: A case series was created, with eight patients with knee osteoarthritis. All subjects received an instrumented knee implant in unilateral TKA. Native computed tomography scans, acquired pre and postoperatively, were used to evaluate distal muscle volumes and fatty infiltration. In vivo tibio-femoral joint loads were measured telemetrically during standing, walking, stair climbing and chair rising and were correlated to muscle status. Results: Postoperatively a reduction in fatty infiltration across all periarticular muscles was pronounced. High average peak loads acted in the tibio-femoral joint ranging from 264% during stand-to-sit activities up to 341% body weight (BW) during stair descent. Fatty infiltration of the m. quadriceps femoris and hamstrings were associated with increased tibio-femoral joint contact forces during walking (r = 0.542; 0.412 and 0.766). Conclusion: The findings suggest that a fatty infiltration of periarticular muscles may lead to increased tibio-femoral joint contact forces. However, we only observed weak correlations between these parameters. Improvements in functional mobility and the restoration of a pain-free joint likely explain the observed postoperative reductions in fatty infiltration. Perioperative rehabilitation approaches targeting residual impairments in muscle quality could, contribute to reduced tibio-femoral joint loads and improved long-term outcomes of TKA. However, it has to be pointed out that the study included a small number of patients, which may limit its validity.

Neuromuscular joint function in knee osteoarthritis: A systematic review and meta-analysis

BACKGROUND

Neuromuscular alterations are common in people with knee osteoarthritis (KOA). A comprehensive understanding of these alterations is important to enable targeted rehabilitation strategies.

OBJECTIVES

This systematic review and meta-analysis aimed to comprehensively understand the neuromuscular alterations around the knee joint in people with KOA.

METHODS

Moderate- and high-quality studies based on a modified version of the Downs and Black checklist, comparing neuromuscular function of peri‑articular muscles between people with KOA and controls were retrieved from five databases from inception to October 2020. Outcomes included normalized isokinetic strength, muscle size, voluntary activation, cortical and spinal-reflex excitability, and torque-related outcomes. Data were pooled according to structural KOA severity with sensitivity analysis based on sex. Evidence levels are presented in evidence gap maps.

RESULTS

A total of 7 high-quality and 22 moderate-quality studies were retained (1146 people with KOA and 1353 age- and sex-matched controls). Studies demonstrated quadriceps and hamstring strength deficits and increased hamstring-to-quadriceps strength ratios across KOA severities. Women presented lower quadriceps strength at early KOA (very limited evidence) and lower voluntary activation at end stage KOA (very limited evidence) as compared with controls, whereas men did not (moderate evidence). People with KOA also demonstrated lower quadriceps force control ability with no change in rapid force production (very limited evidence). Voluntary activation deficits for quadriceps were evident (moderate evidence), with no change in quadriceps cortical excitability (very limited evidence) or soleus spinal reflexes (very limited evidence). No muscle size change was demonstrated except for the vastus medialis (limited evidence). Evidence gaps were found for neural and torque-related measures and differences in hamstring, gastrocnemius, soleus, and popliteus.

CONCLUSIONS

Neuromuscular deficits are evident across different structural KOA severities and are seen in muscle strength, voluntary activation, muscle size, and force control ability. Women may exhibit these alterations to a greater extent than men.

PROSPERO REGISTRATION NUMBER

CRD42019160845.

Differences in Muscle Fatigability of Vastus Medialis between Sexes Using Surface Electromyographic Power Spectral Analysis in Healthy Adults

Objectives:

With a relatively high percentage of type I fibers in the vastus medialis (VM), its fatigability may be more sensitive to the effects of muscle activity in the quadriceps. However, sex-related differences in the muscle fatigability of the VM remain unknown. The purpose of the present study was to assess the differences in fatigability of the VM between healthy adult men and women.

Methods:

Surface electromyographic (EMG) activities of VM oblique (VMO) and VM long (VML) were recorded during sustained isometric contraction on a leg press machine. The results of EMG power spectral analysis were compared between healthy adult men and women. The decline in the median frequency (MF), defined as MF slope, was calculated using spectrum analysis after fast Fourier transform of the raw EMG signals of VMO and VML.

Results:

The endurance time and the MF slopes of the VMO and VML were significantly longer and lower, respectively, in women than in men. The present results demonstrated that both VMO and VML are more fatigue-resistant in women than in men.

Conclusions:

Understanding the sex differences in fatigability could help to design more effective exercise regimens for VMO and VML in healthy individuals. A similar approach should be considered when prescribing practical exercise regimens for patients with muscle atrophy.

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

BACKGROUND

Local neuromuscular deficits have been reported in people with patellofemoral pain. We synthesised the neuromuscular characteristics associated with patellofemoral pain to help identify interventional targets and potential mechanisms.

METHODS

Five databases were searched for local neuromuscular characteristics in case-control studies. Electromyography, flexibility, muscle performance and cross-sectional area data were derived from functional or isolated task investigations and synthesised accordingly. An evidence gap map was constructed.

FINDINGS

Sixty-seven studies were included. In functional tasks, electromyographic investigations showed moderate evidence of small effect for vastus medialis onset-delays relative to vastus lateralis (0.44 [0.03, 0.85]) during stepping/stair negotiation tasks, and higher biceps femoris mean excitation amplitudes (0.55 [0.06, 1.04]) in single-leg triple-hop test. In isolated tasks, we found moderate evidence of medium effect for lower Hoffman-reflex amplitude of vastus medialis (-1.12 [-1.56, -0.67]). Muscle performance investigations showed; strong evidence with medium and small effects for lower extensors concentric (-0.61 [-0.81, -0.40]) and eccentric (-0.56 [-0.79, -0.33]) strength, and moderate evidence of medium effect of lower isometric (-0.64 [-0.87, -0.41]) strength, moderate evidence with small effect for rate of force development to 30% (-0.55[-0.89, -0.21]), 60% (-0.57[-0.90, -0.25]) and medium effect to 90% (-0.76[-1.43, -0.10]) of maximum voluntary contraction, and small effect for lower flexors concentric strength (-0.46 [-0.74, -0.19]) and extensors total work (-0.48 [-0.90, -0.07]). Flexibility investigations showed tighter hamstrings (-0.57 [-0.99, -0.14]).

INTERPRETATION

Differences within quadriceps and hamstrings motor-control, hamstrings tightness, and quadriceps and hamstrings weakness are associated with patellofemoral pain, and can be used to guide investigations of treatment effects.

Botulinum toxin injections as salvage therapy is beneficial for management of patellofemoral pain syndrome

PURPOSE

Patellofemoral pain syndrome (PFPS) is a common pathology usually presenting with anterior or retropatellar pain. It is associated with a relative imbalance between the vastus medialis oblique (VMO) and the vastus lateralis (VL) muscles. This can lead to considerable morbidity and reduced quality of life (QOL). This study aims to assess the long-term functional outcome of PFPS treated with VL muscle botulinum toxin A (BoNT-A) injection.

MATERIALS AND METHODS

A retrospective review was performed on 26 consecutive patients (31 knees) with a mean age of 50.1 years (± 19.7 years) who were treated with BoNT-A injections to the VL muscle followed by physiotherapy between 2008 and 2015. Pre- and post-treatment pain levels (numerical rating scale, NRS), QOL (SF-6D), and functional scores (Kujala and Lysholm questionnaires) were measured. Demographics, physical therapy compliance, previous surgeries, perioperative complications, and patient satisfaction levels were collected.

RESULTS

The mean follow-up time was 58.8 ± 36.4 months. There were significant improvements in all the examined domains. The average pain score (NRS) decreased from 7.6 to 3.2 (P < 0.01), and the Kujala, Lysholm, and SF-6D scores improved from 58.9 to 82.7 (P < 0.001), 56.2 to 83.2 (P < 0.001), and 0.6 to 0.8 (P < 0.001), respectively. Similar delta improvement was achieved irrespective of gender, age, compliance to post-treatment physical therapy, or coexisting osteoarthritis. Patients who presented with a worse pre-treatment clinical status achieved greater improvement. Prior to BoNT-A intervention, 16 patients (18 knees) were scheduled for surgery, of whom 12 (75%, 13 knees) did not require further surgical intervention at the last follow-up.

CONCLUSIONS

A single intervention of BoNT-A injections to the VL muscle combined with physiotherapy is beneficial for the treatment of patients with persistent PFPS.

LEVEL III EVIDENCE

Retrospective cohort study.

Knee Pathology before and after SARS-CoV-2 Pandemic: An Analysis of 1139 Patients

BACKGROUND

The SARS-CoV-2 pandemic drastically changed daily life activities and medical practice, leading to a reorganization of healthcare activities. People spent two months in home-isolation, changing their daily habits and undertaking a more sedentary lifestyle. Change in lifestyle is related to important consequences in knee pathologies. The aim of this study was to evaluate the outpatient activity for knee pathologies before and after lockdown in terms of incidence, severity, diagnosis, and treatment.

METHODS

Medical records of patients with knee pathology in outpatient follow-up at IRCCS Istituto Ortopedico Galeazzi in Milan (Italy) were analyzed in the time frame 4 May-4 September 2020 and compared with patients examined between 4 May and 4 September 2019.

RESULTS

A significant increase of knee diagnoses associated to patellofemoral disorders in 2020 was found (p = 0.004). In addition, physiotherapy was significantly more prescribed in 2020 than in 2019 (p = 0.012).

CONCLUSIONS

The SARS-CoV-2 pandemic lockdown did not drastically change knee pathology, but it may have had an impact on it, highlighting a summary worsening of patellofemoral disorders associated with other knee diagnoses. Further studies are required to validate this result.

Patellofemoral Pain After Arthroscopy: Muscle Atrophy Is Not Everything

Background

It remains unclear as to why patellofemoral pain (PFP) appears in some patients after knee arthroscopy and what influence the quadriceps muscle has on its onset.

Purpose

To compare muscle thickness, neuromuscular contractility, and quadriceps femoris muscle strength between patients who develop PFP after arthroscopic partial meniscectomy and a control group and to compare functional outcomes between these entities.

Study Design

Cohort study; Level of evidence, 3.

Methods

A prospective longitudinal cohort study was carried out on patients scheduled for arthroscopic partial meniscectomy. Patients were excluded if they had preoperative PFP, previous knee surgery, or additional surgical procedures (eg, meniscal repair or microfracture). The following were performed preoperatively: magnetic resonance imaging to quantify muscle thickness, surface electromyography to analyze electrical contractility, and an isokinetic study to assess the strength of the quadriceps femoris muscle. Patients also completed a Lysholm functional questionnaire. Six weeks after the index procedure, patients were questioned about the presence of PFP, and the same tests were repeated. The PFP group included patients who developed anterior knee pain postoperatively, while the control group included those who did not develop pain.

Results

Of 90 initial study patients, 20 were included in the PFP group (23.8%) and 64 in the control group (76.2%); 6 patients were lost to follow-up. Both study groups were comparable on all of the analyzed preoperative variables. Patients in the PFP group had worse results in terms of muscle thickness (9.67 vs 16.55 cm²), electrical contractility (1226.30 vs 1946.11 µV), and quadriceps strength (12.27 vs 20.02 kg; all P < .001). They also presented worse functional results on the Lysholm score (63.05 vs 74.45; P < .001).

Conclusion

Patients who developed PFP after arthroscopic partial meniscectomy had more quadriceps femoris muscle atrophy as well as a greater decrease in electrical contractility and muscle strength at 6 weeks postsurgically as compared with a control group. The PFP group also had worse postoperative functional results.

Selective Atrophy of the Vastus Medialis: Does It Exist in Women With Nontraumatic Patellofemoral Pain?

BACKGROUND

A commonly cited theory related to the pathomechanics of patellofemoral pain (PFP) states that atrophy of the vastus medialis (VM) muscle leads to lateral tracking of the patella. However, isolated atrophy of the VM or atrophy of the quadriceps muscle group as a whole, has not been consistently reported in this population.

PURPOSE

To compare individual and total quadriceps muscle volumes between women with nontraumatic PFP and women without PFP as measured on magnetic resonance imaging scans.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A total of 52 women with nontraumatic PFP and 64 women without PFP between the ages of 18 and 45 years participated. Magnetic resonance imaging scans of the thigh were obtained from the anterior inferior iliac spine to the tibial plateau. Individual quadriceps muscle cross-sectional area measurements were obtained from each image, and muscle volumes for the VM, vastus lateralis, vastus intermedius, and rectus femoris were calculated. Muscle volume measurements were expressed in absolute values and normalized to body mass. Separate 2-way mixed-factorial analysis of variance (group × muscle) were used to compare absolute and normalized individual muscle volumes between groups. Independent t tests were used to compare absolute and normalized total quadriceps volumes between groups.

RESULTS

There was no difference in absolute and normalized individual muscle volumes between individuals with and those without PFP. Additionally, absolute and normalized total muscle volumes did not differ between groups.

CONCLUSION

Our findings do not support the concept of preferential atrophy of the VM or generalized quadriceps atrophy in women with nontraumatic PFP.

Dose atrophy of vastus medialis obliquus and vastus lateralis exist in patients with patellofemoral pain syndrome

Background

Whether vastus medialis obliquus atrophy exists in patients with patellofemoral pain syndrome and whether the amount of atrophy differs between the vastus medialis obliquus and vastus lateralis muscles remain unknown.

Materials

From June 2016 to March 2019, 61 patients with patellofemoral pain syndrome were retrospectively included in the study group, and an age-, sex-, and body mass index-matched cohort of 61 patients with normal knees was randomly selected as the control group. All enrolled subjects had undergone CT scans in the supine position. The cross-sectional areas of the vastus medialis obliquus and the vastus lateralis muscle in the sections 0, 5, 10, 15, and 20 mm above the upper pole of the patella were measured, and the vastus medialis obliquus/vastus lateralis muscle area ratio was evaluated.

Results

In the study group, the vastus medialis obliquus areas and the vastus lateralis muscle areas in the sections that were 0, 5, 10, 15, and 20 mm above the upper pole of the patella were significantly smaller than the respective areas in the control group (P < 0.05). The vastus medialis obliquus/vastus lateralis muscle area ratio was significantly smaller at the upper pole of the patella (the section 0 mm above the upper pole of the patella) than the corresponding ratio in the control group (P < 0.05). No significant difference was noted between the two groups in the sections 5, 10, 15, and 20 mm above the upper pole of the patella (P > 0.05).

Conclusion

In patients with patellofemoral pain syndrome, vastus medialis obliquus and vastus lateralis muscle atrophy existed in sections 0–20 mm above the upper pole of the patella, compared with normal controls, and atrophy of the vastus medialis obliquus was more evident than that of the vastus lateralis muscle at the upper pole of the patella. These findings support the rationale for the use of general quadriceps exercise combined with vastus medialis obliquus strengthening exercise as part of the rehabilitation programme for the patients with patellofemoral pain syndrome.

Proximal, Local, and Distal Muscle Morphology in Women With Patellofemoral Pain

Objective:

The objective of this study was to compare proximal, local, and distal muscle morphology in women with and without patellofemoral pain (PFP).

Materials and Methods:

Proximal, local, and distal muscle thicknesses (MTs) were obtained with B-mode sonography in healthy (control group [CG], n = 20) and PFP (PFP group, n = 20) women. In addition, muscle mass was measured by the sum of the synergistic MTs. Data were analyzed by independent t-test, Mann-Whitney U test, and effect size.

Results:

PFP women had smaller gluteus medius ( P = .02, d = 0.7), vastus medialis ( P < .01, d = 1.0), and flexor digitorum brevis ( P < .01, d = 1.0) MT and greater gastrocnemius medialis ( P = .04, d = 0.6) MT than CG. Quadriceps muscle mass ( P = .01, d = 0.8) and foot muscle mass ( P = .008, d = 0.9) were smaller, while plantar flexor muscle mass was greater in the PFP group than in CG ( P = .01, d = 0.8).

Conclusion:

PFP women have proximal, local, and distal MT alterations in comparison with CG, which may explain possible changes in muscle strength and functionality.

Morphological study of the vastus medialis oblique in recurrent patellar dislocation based on magnetic resonance images

Background

To investigate the morphological parameters of the vastus medialis obliquus (VMO) muscle and delineate its importance in the maintenance of patellofemoral joint stability.

Methods

The magnetic resonance imaging data of seventy-five knees (fifty-four patients) with recurrent lateral patella dislocation (LPD) and seventy-five knees (seventy patients) without recurrent LPD were retrospectively analysed. Five morphological parameters related to the VMO (elevation in the sagittal plane and coronal plane, craniocaudal extent, muscle-fibre angulation, cross-sectional area ratio) and two patella tilt parameters (patella tilt angle, bisect offset ratio) were measured in MR images. The independent-samples t test or chi-square test was used for statistical comparisons.

Results

The mean ages of the patients in the recurrent LPD group and control group were 22.1 ± 9.9 years and 24.0 ± 6.5 years, respectively. Eighteen out of seventy-five (24%) patients MRI showed VMO injuries. Compared with the control group, the patients with recurrent LPD showed significantly higher sagittal VMO elevation (10.4 ± 2.3 mm vs. 4.1 ± 1.9 mm), coronal VMO elevation (15.9 ± 5.7 mm vs. 3.9 ± 3.7 mm), muscle-fibre angulation (35.4 ± 8.0° vs. 27.9 ± 6.3°), patella tilt angle (25.9 ± 10.7° vs. 9.1 ± 5.2°), and bisect offset ratio values (0.9 ± 0.3 vs. 0.5 ± 0.1) and significantly lower craniocaudal extent (13.7 ± 5.3 mm vs. 16.7 ± 5.1 mm) and cross-sectional area ratio values (0.05 ± 0.02 vs. 0.07 ± 0.02).

Conclusions

The results showed that abnormalities in the VMO and patella tilt were clearly present in recurrent LPD patients compared with normal people.

Quadriceps architecture in individuals with patellofemoral pain: A systematic review

OBJECTIVES

To identify differences in architectural parameters (size, fiber/pennation angle, fiber length, and echogenicity) of the quadriceps muscle, as a whole or any individual part of it, using imaging techniques in individuals with patellofemoral pain (PFP) compared to contralateral, asymptomatic limb or separate control group.

BACKGROUND

Quadriceps muscles imbalance and weakness were proposed as risk factors for developing PFP. Although the muscle architecture (size, pennation/fiber angle and fiber length) is highly associated with skeletal muscle strength, it is not clear whether atrophy or any changes in architectural parameters of the quadriceps are presented in the PFP patients.

METHODS

Observational studies in which the total size of the quadriceps or individual parts of it were measured using imaging techniques in the PFP patients were included in this review. Electronic databases (PubMed, SCOPUS, PEDro, CINAHL, WOS, and EMBASE) were searched between January 1990 and December 2019 with no restriction of language. Study selection and data extraction and quality assessment were conducted by two independent reviewers.

RESULTS

Five cross-sectional studies were eligible to include in this review. Three out of five included studies that assessed the total size of the quadriceps and reported no significant differences between the PFP and healthy control group. Two out of five of the studies assessed the total size of the quadriceps between the symptomatic and asymptomatic limb of the PFP patients and reported the statistical difference between limbs. Only one study measured the fiber angle of the VMO muscle at the patella. Controversial results were found between studies that assessed the size of individual parts of the quadriceps.

CONCLUSION

Due to the controversial results of the included studies, this systematic review failed to draw a conclusion on the role of quadriceps atrophy in PFP pathology. The limitation in PFP literature considering pennation/fiber angle, echogenicity and fiber length of individual parts of the quadriceps muscle, rises the need for research that focuses on the biomechanical properties of the quadriceps in PFP patients.

The effects of a standard elliptical vs. a modified elliptical with a converging footpath on lower limb kinematics and muscle activity

Elliptical trainers that increase the inter-pedal distance may have potential benefits for knee osteoarthritis by decreasing the amount of knee varus. Modifying elliptical trainers with a converging footpath and reduced inter-pedal distance may be beneficial for reducing anterior knee pathology risk by decreasing knee valgus angles. Twenty-one college students participated in a single testing session. Participants exercised on two different elliptical trainers, one modified with a converging footpath and reduced inter-pedal width, and a standard elliptical trainer. Participants exercised for 2 min at three ramps incline at 120 strides per minute and constant work rate. Three-dimensional kinematics and electromyography of the dominant lower limb were recorded. Multiple 2 × 3 (Elliptical x Incline) ANOVAs with Bonferroni corrections were used to compare the two elliptical trainers at each incline for kinematics and muscle activity. The modified elliptical trainer displayed significantly decreased peak knee valgus (p = 0.031, η p 2 = 0.234 ), peak knee flexion (p = 0.006, η p 2 = 0.246 ), and interactions for peak knee flexion (p = 0.001, η p 2 = 0.250 ) and vastus lateralis (p < 0.01, η p 2 = 0.380 ) muscle activity compared to the standard elliptical trainer. The decreased peak knee valgus and flexion angles could be beneficial for reducing long-term injury risk for anterior knee pathologies.

Bottom-Up Kinetic Chain in Drop Landing among University Athletes with Normal Dynamic Knee Valgus

The study investigated the influence of ankle strength and its range of motion (ROM) on knee kinematics during drop landing. Fifteen male and fifteen female university athletes with a normal range of dynamic knee valgus (DKV) (knee frontal plane projection angle: men = 3° to 8°, females = 7° to 13°) were recruited. They performed drop landing at height 30 cm and 45 cm with three-dimensional motion capture and analysis. Knee angles were compared at specific landing phases. Isokinetic ankle strength was tested at 60°/s angular velocity while the weight-bearing lunge test was conducted to evaluate ankle ROM. For males, strength for both plantarflexors and dorsiflexors were associated with knee kinematics at both heights (30 cm: r = −0.50, p = 0.03; 45 cm: r = −0.45, p = 0.05) during maximum vertical ground reaction force (MVGRF) phase. For females, ankle invertor strength and knee kinematics were associated at both 30cm (r = 0.53; p = 0.02,) and 45 cm landing heights (r = 0.49, p = 0.03), while plantarflexor strength and knee kinematics showed a significant association during initial contact (r = 0.70, p < 0.01) and MVGRF (r = 0.55, p = 0.02) phases at height 30 cm only. Male and female athletes with normal range of DKV showed a significant relationship between ankle strength and knee kinematics at specific landing phases. These relationships varied with increased landing height.

Hip muscle atrophy in patients with acetabular labral joint pathology

Intra-articular hip joint pathology is a source of hip and groin pain in active individuals and is thought to be a precursor to hip osteoarthritis. Limited evidence exists to guide appropriate physiotherapy management for these patients. Identification of which hip muscles are affected may help clinicians to develop effective exercise programs. A cross-sectional observational study in a hospital setting was conducted to investigate the size of individual hip abductor, hip extensor, and hip external rotator muscles in patients with acetabular labral joint pathology compared with age and sex matched healthy subjects. Twelve participants (eight females, four males), aged 20-53 years, with a medical diagnosis of unilateral acetabular labral tear and 12 healthy participants were recruited. Magnetic resonance imaging was used to assess cross-sectional areas of the gluteus minimus, gluteus medius, upper gluteus maximus, lower gluteus maximus, piriformis, and quadratus femoris muscles bilaterally. Gluteus medius muscle cross-sectional area was significantly different between groups (P < 0.01, effect size = 0.92) with muscle size found to be smaller in the pathology group. No differences were found for the other hip muscles (P > 0.05). These findings suggest that hip muscles are not all affected equally by the presence of intra-articular hip joint pathology. Atrophy of specific hip muscles, which are important in hip joint and pelvic stability, may alter hip joint function during gait and functional tasks. Clinicians treating patients with intra-articular hip joint pathology may need to prescribe exercises targeting the specific muscles with demonstrated dysfunction. Clin. Anat. 33:538-544, 2020. © 2019 Wiley Periodicals, Inc.

Comparison of dry needling and ischaemic compression techniques on pain and function in patients with patellofemoral pain syndrome: a randomised clinical trial

BACKGROUND

To compare the effectiveness of ischaemic compression (IC) applied directly to the knee versus dry needling (DN) with respect to pain, functional status and sensitivity to mechanical stimulation of vastus medialis obliquus (VMO) myofascial trigger points (MTrPs) in patients with patellofemoral pain syndrome (PFPS).

METHODS

A total of 54 patients with unilateral PFPS aged 20-30 years were selected randomly from patients referred to physical therapy clinics of Babol University of Medical Sciences in Iran. Twenty-seven patients were allocated to either IC or DN groups. Three sessions of treatment were applied over 1 week with follow-up at 1 week, 1 month and 3 months. Primary outcome measures comprised the Kujala questionnaire score for functional status, numerical pain rating scale (NPRS) for pain intensity and pressure pain threshold (PPT) for sensitivity to mechanical stimulation; these were measured and recorded before treatment and 1 week, 1 month and 3 months after the last treatment session.

RESULTS

There were no statistically significant differences in the between-group comparisons of any variables at the various follow-up points. Both groups (n = 27 participants each) had significant improvements (p < 0.05) in pain, functional status and PPT values at follow-up.

CONCLUSIONS

There were no differences in markers of pain, function or pressure sensitivity over a 3-month follow-up period between patients with PFPS treated with DN and IC. Temporal improvements in both groups suggested that the two techniques may be similarly effective for the treatment of PFPS.

Unilateral and bilateral patellofemoral pain in young female dancers: Associated factors

Aiming to evaluate the prevalence of unilateral/bilateral patellofemoral pain (PFP) among young dancers, and to investigate whether different factors are associated with PFP in young dancers, 132 dancers aged 12-14 years were assessed for PFP. Anthropometric parameters, proprioception ability, dynamic postural balance (DPB), and muscle strength were measured. PFP was found in 64.1% of the dancers. No significant differences in the prevalence of dancers with no, unilateral, or bilateral PFP at different ages were found. Significant age effects were found for anthropometric and developmental measurements, and for intensity of training. PFP effect was found for DPB asymmetry, ankle proprioception, and leg-length %height. A higher hip abductor/adductor ratio was associated with PFP in 14-year-old dancers. Binomial logistic regression showed that increased number of hours per day (h/day) and decreased number of hours per week (h/week), low proprioception scores, greater leg length as %height, and more anterior DPB asymmetry were significant predictors of PFP. In conclusion: unilateral/bilateral PFP is common among young dancers. Body morphology, reduced ankle proprioception ability, DPB asymmetry, and increased h/day of practice are associated with PFP. Dance teachers should start monitoring the impact of training and implement injury modification/prevention strategies when their students are at a young age.

Adaptation of muscle activation after patellar loading demonstrates neural control of joint variables

We evaluated whether the central nervous system (CNS) chooses muscle activations not only to achieve behavioral goals but also to minimize stresses and strains within joints. We analyzed the coordination between quadriceps muscles during locomotion in rats before and after imposing a lateral force on the patella. Vastus lateralis (VL) and vastus medialis (VM) in the rat produce identical knee torques but opposing mediolateral patellar forces. If the CNS regulates internal joint stresses, we predicted that after imposing a lateral patellar load by attaching a spring between the patella and lateral femur, the CNS would reduce the ratio between VL and VM activation to minimize net mediolateral patellar forces. Our results confirmed this prediction, showing that VL activation was reduced after attaching the spring whereas VM and rectus femoris (RF) activations were not significantly changed. This adaptation was reversed after the spring was detached. These changes were not observed immediately after attaching the spring but only developed after 3–5 days, suggesting that they reflected gradual processes rather than immediate compensatory reflexes. Overall, these results support the hypothesis that the CNS chooses muscle activations to regulate internal joint variables.

Patellofemoral MRI Alterations Following Single Bundle ACL Reconstruction with Hamstring Autografts Are Associated with Quadriceps Femoris Atrophy

High incidence of patellofemoral pain and patellofemoral joint osteoarthritis was found following anterior cruciate ligament (ACL) reconstruction. The unstability of patellofemoral joint might be an important contribution factor. This study was designed to define the relationship between the unstability of patellofemoral joint and quadriceps femoris atrophy. Twenty patients underwent MRI scan before ACL reconstruction and every two weeks after surgery, until 12 weeks. The merchant's patellar congruence angle, lateral inclination angle, and quadriceps femoris muscle cross-sectional area were measured and the relationship between the changes of angles and the ratio of quadriceps femoris atrophy was studied by multiple regression analysis. Significant quadriceps femoris atrophy was observed after ACL reconstruction during the follow-up period of 12 weeks. The merchant's patellar congruence angle and lateral inclination angle significantly changed after surgery. The alterations of the merchant's patellar congruence angle were significantly correlated with the atrophy ratio of vastus medialis (coefficient=-15.76) and vastus lateralis (coefficient=8.35) during the follow-up period of 12 weeks. The alterations of lateral inclination angle were significantly correlated with the atrophy ratio of vastus medialis (coefficient=20.62), vastus lateralis (coefficient=-11.38) and rectus femoris (coefficient=-0.469) during the follow-up period 12 weeks. To sum up, ACL reconstruction can alleviate the dysfunction of patellofemoral joint to a certain extent. But, the unbalanced atrophy of quadriceps femoris once again destroyed the stability of patellofemoral joint following the operation, which might be one cause of patellofemoral joint pain and early onset of osteoarthritis after ACL reconstruction. So, rehabilitation training that focuses on quadriceps femoris especially the vastus medialis shortly following operation is suggested.

Update of Risk Factors, Diagnosis, and Management of Patellofemoral Pain

PURPOSE OF REVIEW

Patellofemoral pain is the most common cause of anterior knee pain. The purpose of this review is to examine the latest research on risk factors, physical examination, and treatment of patellofemoral pain to improve accuracy of diagnosis and increase use of efficacious treatment modalities.

RECENT FINDINGS

The latest research suggests patellofemoral pain pathophysiology is a combination of biomechanical, behavioral, and psychological factors. Research into targeted exercise therapy and other conservative therapy modalities have shown efficacy especially when used in combination. New techniques such as blood flow restriction therapy, gait retraining, and acupuncture show promise but require further well-designed studies. Patellofemoral pain is most commonly attributed to altered stress to the patellofemoral joint from intrinsic knee factors, alterations in the kinetic chain, or errors in training. Diagnosis can be made with a thorough assessment of clinical history and risk factors, and a comprehensive physical examination. The ideal treatment is a combination of conservative treatment modalities ideally individualized to the risk factors identified in each patient. Ongoing research should continue to identify biomechanical risk factors and new treatments as well as look for more efficient ways to identify patients who are amenable to treatments.

Quadriceps architecture in individuals with patellofemoral pain: a systematic review protocol

OBJECTIVE

The objective of this review is to identify differences in quadriceps architectural parameters between healthy individuals and those with patellofemoral pain (PFP).

INTRODUCTION

Patellofemoral pain is one of the most common causes of knee pain among physically active populations. Muscular imbalance may play an important role in patellar malalignment or patellar maltracking. A systematic review will clarify the possible architectural changes of quadriceps muscles in persons with PFP.

INCLUSION CRITERIA

Eligible observational studies will include individuals younger than 50 years who have been diagnosed with unilateral or bilateral PFP. The comparator will be the contralateral, asymptomatic limb of the individual with PFP or a healthy matched subject. Studies that include measurement of quadriceps muscle size as the primary outcome will be considered. Studies in which participants had coexisting pathology, a history of lower limb surgery or injury, or pain originating from other joints will be excluded.

METHODS

PubMed/MEDLINE (NLM), Scopus, Embase, Physiotherapy Evidence Database, Web of Science and CINAHL databases and multiple gray literature sources will be searched. Studies published since 1 January 1990 will be considered; there will be no language restriction. Retrieval of full-text studies, assessment of methodological quality and data extraction will be performed independently by two reviewers. If possible, meta-analyses will be performed, and a Grading of Recommendations, Assessment, Development and Evaluation (GRADE) Summary of Findings presented.

Ultrasonographic assessment of quadriceps and patellar tendon thicknesses in patients with patellofemoral pain syndrome

Objective

The aim of this study was to compare ultrasonographically measured quadriceps and patellar tendon thicknesses between Patellofemoral Pain Syndrome (PFPS) patients and age- and gender-matched healthy controls.

Methods

Among patients who presented to physical therapy and rehabilitation outpatient clinic in January–December 2016, 61 volunteers (28 men and 33 women; mean age: 30.79 ± 6.55 years) who were eligible considering the inclusion and exclusion criteria were enrolled. 30 were diagnosed with PFPS, and the remaining were age- and gender-matched healthy volunteers. Mean age was 30.03 ± 5.67 years in healthy subjects and 45.2% were of male gender. The patient group had mean age of 31.57 ± 7.37 years and 46.7% of the patients were male. Q angles were measured at standing, supine and sitting positions. Patellar and femoral tendon thicknesses and areas were measured ultrasonographically. Kujala questionnaire were used to evaluate the functional status of the participants.

Results

No significant difference was detected between groups regarding profession, educational background, and body mass indices (BMI) (p > 0.05). Q angle values were significantly higher in the patient group when compared to controls at standing (17.03 ± 3.84 vs. 13.87 ± 1.75°, p < 0.001), supine (16.20 ± 3.74 vs. 13.45 ± 1.79°, p = 0.001) and sitting (16.50 ± 3.28 vs. 13.71 ± 1.72°, p < 0.001) positions. Kujala score was significantly lower in the PFPS group when compared to controls (70.57 ± 8.37 vs. 98.58 ± 2.05, p < 0.001). Patellar (0.39 ± 0.08 vs. 0.32 ± 0.05 cm, p < 0.001) and quadriceps (0.64 ± 0.10 vs. 0.52 ± 0.09 cm, p < 0.001) tendon thicknesses were significantly higher in the PFPS group when compared to controls. There was no significant difference between groups regarding patellar tendon areas (p > 0.05). Patellar tendon thickness values of ≥0.35 cm were found to have 66.7% sensitivity and 67.7% specificity for PFPS diagnosis in the ROC curve analysis (area under curve: 0.771, 95% confidence interval: 0.655–0.887, p < 0.001). Quadriceps tendon thickness values of ≥0.54 cm were found to have 80% sensitivity and 71% specificity for PFPS diagnosis in the ROC curve analysis (area under curve: 0.824, 95% confidence interval: 0.710–0.939, p < 0.001). In PFPS patients, quadriceps tendon thickness had significant positive correlation with age (r = 0.405, p = 0.027) and BMI (r = 0.450, p = 0.013); and significant negative correlation with Kujala score (r = −0.441, p = 0.015). In the multivariate regression analysis, quadriceps tendon thickness was independently associated with the presence of PFPS (Exp (B): 3.089, 95% confidence interval: 1.344–7.100, p = 0.008).

Conclusion

Our study demonstrates that ultrasonographically measured patellar and quadriceps tendon thicknesses are significantly higher in subjects with PFPS and particularly, quadriceps tendon thickness may be used for the diagnosis.

Level of Evidence

Level III, Therapeutic Study.

Regional Vastus Medialis and Vastus Lateralis Activation in Females with Patellofemoral Pain

INTRODUCTION

This study aimed to investigate whether regional activation patterns in the vasti muscles differ between females with and without patellofemoral pain (PFP), and whether muscle activation patterns correlate with knee extension strength.

METHODS

Thirty-six females with PFP and 20 pain-free controls performed a standardized knee flexion-extension task. The activation of vastus medialis (VM) and vastus lateralis (VL) was collected using high-density surface EMG and analyzed using principal component (PC) analysis. Spatial locations and temporal coefficients of the PC, and the percent variance they explain, were compared between groups and between the concentric and the eccentric phases of the movement. Correlations were assessed between PC features and knee extension strength.

RESULTS

The spatial weights of PC1 (general vasti activation) and PC2 (reflecting vastus-specific activation) were similar between groups (R > 0.95). Activation patterns in PFP were less complex than controls. Fewer PC features were necessary to reconstruct 90% of the signal for PFP participants in the concentric phase (P < 0.05), and the difference in bias of activation to VM (concentric phase) or VL (eccentric phase) was less between phases for PFP participants (P < 0.05). Smaller difference in vastus-specific activation in concentric and eccentric phases (less task specificity of VM/VL coordination) was related to greater maximal knee extension strength (P < 0.05, R < -0.43).

CONCLUSION

These data suggest PFP involves a simpler control strategy of VM and VL. The inverse association between task specificity and maximal knee extension strength suggests different presentations of PFP: lower knee extension strength but VM/VL coordination task specificity comparable with controls, or knee extension strength comparable with controls but lower VM/VL coordination task specificity.

Vastus lateralis and vastus medialis produce distinct mediolateral forces on the patella but similar forces on the tibia in the rat

Improper activation of the quadriceps muscles vastus medialis (VM) and vastus lateralis (VL) has been implicated in the development of patellofemoral pain (PFP). This explanation of PFP assumes that VM and VL produce opposing mediolateral forces on the patella. Although studies have provided evidence for opposing actions of VM and VL on the patella, other studies have suggested that their actions might be similar. In this study, we took advantage of the experimental accessibility of the rat to directly measure the forces on the patella produced by VM and VL. We found that VM and VL produce opposing mediolateral forces on the patella when the patella was lifted away from the femur. These distinct mediolateral forces were not transmitted to the tibia, however: forces measured at the distal tibia were very similar for VM and VL. Further, when the patella was placed within the trochlear groove, the forces on the patella produced by VM and VL were very similar to one another. These results suggest that mediolateral forces produced by VM and VL are balanced by reaction forces from the trochlear groove and so are not transmitted to the tibia. These results provide a rich characterization of the mechanical actions of VM and VL and have implications about the potential role of these muscles in PFP and their neural control during behavior.

A cadaveric model to evaluate the effect of unloading the medial quadriceps on patellar tracking and patellofemoral joint pressure and stability

BACKGROUND

Vastus Medialis Muscles (VMM) damage has been widely identified following patellar dislocation. Rehabilitation programmes have been suggested to strengthen the VMM and reduce clinical symptoms of pain and instability. This controlled laboratory study investigated the hypothesis that reduced Vastus Medialis Obliquus (VMO) and Vastus Medialis Longus (VML) muscle tension would alter patellar tracking, stability and PFJ contact pressures.

METHODS

Nine fresh-frozen dissected cadaveric knees were mounted in a rig with the quadriceps and iliotibial band loaded to 205 N. An optical tracking system measured joint kinematics and pressure sensitive film between the patella and trochlea measured PFJ contact pressures. Measurements were repeated for three conditions: 1. With all quadriceps heads and iliotibial band (ITB) loaded; 2. as 1, but with the VMO muscle unloaded and 3. as 1, but with the VMO and VML unloaded. Measurements were also repeated for the three conditions with a 10 N lateral displacement force applied to the patella.

RESULTS

Reduction of VMM tension resulted in significant increases in lateral patellar tilt (2.8°) and translation (4 mm), with elevated lateral and reduced medial joint contact pressures from 0.48 to 0.14 MPa, and reduced patellar stability (all p < 0.05).

CONCLUSIONS

These findings provide basic scientific rationale to support the role of quadriceps strengthening to resist patellar lateral maltracking and rebalance the articular contact pressure away from the lateral facet in patients with normal patellofemoral joint anatomy.

Relationship Between Lower-Extremity Strength and Subjective Function in Individuals With Patellofemoral Pain

Objective: Evaluate the relationship between subjective knee function and lower-extremity strength in individuals with patellofemoral pain (PFP). Design: Cohort. Setting: Laboratory. Participants: Participants were 30 individuals with PFP (20 females and 10 males; 76.02 [17.88] kg, 173.04 [7.58] cm, and 24.9 [7] y). Main Outcome Measures: Subjects completed the Activities of Daily Living Scale (ADLS) and had lower-extremity hip and knee isometric strength assessed. Strength was compared between low and high subjective functioning ADLS groups. Correlations for strength and subjective function were assessed, with a linear regression utilized to determine if strength predicted subjective function. Results: Quadriceps strength was significantly greater in the high subjective function group (38.5 [13.9] percent body mass) than in the low subjective function group (27.88 [8.96] percent body mass, P = .02). Significant correlations were seen between the ADLS and all 5 lower-extremity strength measures (r = .376–.535). Quadriceps strength was a strong predictor of subjective function in those with PFP, explaining 28.6% of the total variance in the ADLS. Conclusions: Quadriceps strength was a strong predictor of subjective function when assessed by the ADLS in patients with PFP and significantly greater in those with higher subjective function. A strong relationship exists between self-reported function and lower-extremity strength, suggesting the need to evaluate and treat lower-extremity weakness.

Patellofemoral pain syndrome in female athletes: A review of diagnoses, etiology and treatment options

Patellofemoral pain syndrome (PFPS) is one of the most common causes of knee pain and is present in females disproportionately more relative to males. PFPS causes tend to be multifactorial in nature and are described in this review. From a review of the current literature, it is clear that there needs to be further research on PFPS in order to better understand the complex etiology of this disorder in both males and females. It is known that females with patellofemoral pain syndrome demonstrate a decrease in abduction, external rotation and extension strength of the affected side compared with healthy patients. Conservative management, including optimizing muscle balance between the vastus medialis and lateralis around the patella along with formal therapy should be the first line of treatment in patients presenting with PFPS. Surgery should be reserved for patients in which all conservative management options have failed. This review aims to guide physicians in accurate clinicaldecision making regarding conservative and surgical treatment options when specifically faced with PFPS in a female athlete. Furthermore, we will discuss the anatomic variants, incidence and prevalence, etiology, diagnosis and treatment of PFPS.

The Anatomy of the Articularis Genus Muscle and Its Relation to the Extensor Apparatus of the Knee

Background:

The anatomy of the articularis genus muscle has prompted speculation that it elevates the suprapatellar bursa during extension of the knee joint. However, its architectural parameters indicate that this muscle is not capable of generating enough force to fulfill this function. The purpose of the present study was to investigate the anatomy of the articularis genus, with special emphasis on its relationship with the adjacent vastus intermedius and vastus medialis muscles.

Methods:

The articularis genus muscle was investigated in 18 human cadaveric lower limbs with use of macrodissection techniques. All components of the quadriceps muscle group were traced from origin to insertion, and their affiliations were determined. Six limbs were cut transversely in the middle third of the thigh. The modes of origin and insertion of the articularis genus, its nerve supply, and its connections with the vastus intermedius and vastus medialis were studied.

Results:

The muscle bundles of the articularis genus were organized into 3 main layers: superficial, intermediate, and deep. The bundles of the superficial layer and, in 60% of the specimens, the bundles of the intermediate layer originated from both the vastus intermedius and the anterior and anterolateral surfaces of the femur. The bundles of the deep layer and, in 40% of the specimens, the bundles of the intermediate layer arose solely from the anterior surface of the femur. The distal insertion sites included different levels of the suprapatellar bursa and the joint capsule. A number of connections between the articularis genus and the vastus intermedius were found. While the vastus medialis inserted into the whole length of the vastus intermedius aponeurosis, it included muscle fibers of the articularis genus, building an intricate muscle system supplied by nerve branches of the same medial deep division of the femoral nerve.

Conclusions:

The articularis genus, vastus medialis, and vastus intermedius have a complex, interacting architecture, suggesting that the articularis genus most likely does not act as an independent muscle. With support of the vastus intermedius and vastus medialis, the articularis genus might be able to function as a retractor of the suprapatellar bursa. The finding of likely interplay between the articularis genus, vastus intermedius, and vastus medialis is supported by their concurrent innervation.

Clinical Relevance:

The association between the articularis genus, vastus medialis, and vastus intermedius may be more complex than previously believed, and this close anatomical connection could have functional implications for knee surgery. Dysfunction, scarring, or postoperative arthrofibrosis of the sophisticated interactive mechanism needs further investigation.

Effect of knee alignment on the quadriceps femoris muscularity: Cross-sectional comparison of trained versus untrained individuals in both sexes

Knee alignment is suggested to be a factor affecting each quadriceps femoris muscle size, and knee alignment such as Q-angle differs between men and women. Also, training can induce inhomogeneous hypertrophy among the quadriceps femoris, thereby leading to different component characteristics of the muscles. If Q-angle is a major determinant of the quadriceps femoris muscularity, it is hypothesized that the sex-related difference in the quadriceps femoris muscularity, if any, is further highlighted in trained individuals, being associated with Q-angle. We tested this hypothesis. Magnetic resonance images of the right thigh were obtained from 26 varsity rowers as trained subjects (13 for each sex) and 34 untrained individuals as controls (17 for each sex). From the images, muscle volume of each constituent of the quadriceps femoris (vastus lateralis, VL; medialis, VM; intermedius; rectus femoris) was determined. The Q-angle was measured during quiet bilateral standing with hand support as needed. Percent volume of VM to the total quadriceps femoris was greater in female rowers than male rowers and female controls, and that of VL was greater in male rowers than male controls. There were no correlations between Q-angle and percent muscle volume in any muscles regardless of rowing experience or sex. The current study revealed that well-trained rowers have sex-related quadriceps femoris muscularity but no significant correlations between percent muscle volume in any muscles and Q-angle. Our findings suggest that Q-angle is not a major determinant of the quadriceps femoris muscularity in either well-trained or untrained individuals.

Significance of Diffusion Tensor Imaging of Vastus Medialis Oblique in Recurrent Patellar Dislocation

Background:

Numerous studies have investigated the influence of osseous factors on patellofemoral joint instability, but research on the influence of dynamic muscle factors in vivo is still in the exploratory stage. This study aimed to use magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) to evaluate vastus medialis oblique (VMO) fiber bundles in patients with recurrent patellar dislocation to explore the changes in muscle morphology and function.

Methods:

This prospective study involved 30 patients (7 males and 23 females; average age, 21.4 ± 3.8 years) clinically diagnosed with recurrent patellar dislocation in Peking University Third Hospital and 30 healthy volunteers matched for age, sex, and body mass index in our medical school between January 2014 and October 2014. None of the patients had a recent history of traumatic patellar dislocation or transient patellar dislocation. All patients underwent conventional MRI and DTI of the knee. The cross-sectional area of the VMO on MRI and the fractional anisotropy (FA), apparent diffusion coefficient (ADC), and primary (λ1), secondary (λ2), and three-level characteristic (λ3) values on DTI were measured. The independent-samples t-test was used to compare these parameters between the two groups.

Results:

Compared with the control group, the patient group showed significantly higher FA values (0.39 ± 0.05 vs. 0.33 ± 0.03) and significantly lower ADC (1.51 ± 0.13 vs. 1.58 ± 0.07), λ2 (4.96 ± 0.13 vs. 5.04 ± 0.07), and λ3 values (4.44 ± 0.14 vs. 4.58 ± 0.07; t = 5.99, t = –2.58, t = –3.02, and t = –4.88, respectively; all P < 0.05). Cross-sectional VMO area and λ1 values did not differ between the two groups (t = –1.82 and t = 0.22, respectively; both P > 0.05).

Conclusions:

The functional status of the VMO is closely associated with recurrent patellar dislocation. MRI, especially DTI (FA, ADC, λ2, and λ3), can detect early changes in VMO function and might facilitate the noninvasive monitoring of the functional status of the VMO in patients with recurrent patellar dislocation.

Patellofemoral Pain

Patellofemoral pain is characterized by insidious onset anterior knee pain that is exaggerated under conditions of increased patellofemoral joint stress. A variety of risk factors may contribute to the development of patellofemoral pain. It is critical that the history and physical examination elucidate those risk factors specific to an individual in order to prescribe an appropriate and customized treatment plan. This article aims to review the epidemiology, risk factors, diagnosis, and management of patellofemoral pain.

Lower extremity rotational deformities and patellofemoral alignment parameters in patients with anterior knee pain

PURPOSE

Anterior knee pain is a common musculoskeletal condition amongst young adult population. Lower extremity structural factors, such as increased femoral anteversion and lateral tibial torsion, may contribute to patellofemoral malalignment and anterior knee pain. The aim of this study was to evaluate the lower extremity structural factors and related patellofemoral alignment parameters that play a role in the aetiology of anterior knee pain.

METHODS

This study involved three groups: patients with unilateral symptomatic knees (n = 35), asymptomatic contralateral knees in the same patients and a control group (n = 40). All subjects were physically examined, and Q-angles were measured. The lower extremities of all subjects were imaged by a very low-dose CT scan, and the symptomatic knees of patients were compared with their asymptomatic contralateral knees and with the healthy knees of controls regarding femoral anteversion, tibial torsion, sulcus angle, patellar tilt angle and lateral patellar displacement.

RESULTS

Regarding the Q-angle, femoral anteversion and lateral tibial torsion, no significant differences were found between the symptomatic and asymptomatic knees, whereas significant differences were found between the symptomatic knees and controls. The symptomatic group demonstrated significantly greater sulcus angle only in 30° of knee flexion than did the controls.

CONCLUSION

Patients with unilateral anterior knee pain may have similar morphology at their contralateral asymptomatic lower extremity, and different morphology compared with healthy controls. Lower extremity rotational deformities may increase the risk of anterior knee pain; however, these deformities alone are not sufficient to cause knee pain, and may be predisposing factor rather than a direct aetiology.

LEVEL OF EVIDENCE

Diagnostic study, Level III.

Sagittal patellar tilt and concomitant quadriceps hypotrophy after tibial nailing

PURPOSE

The aim of the study was to analyse the patellofemoral alignment in the sagittal plane following tibial fracture surgery with intramedullary nailing and its relationship to parapatellar muscle status.

METHODS

The patellofemoral MRI results of 27 patients (15 males and 12 females) treated with locked intramedullary nailing following tibia shaft fracture were reviewed. The mean age of the patients was 41.8 (±15) years. The patella-patellar tendon angle (P-PT) and the distance between the inferior patellar pole and the tibial tubercle (DP-TT) were evaluated for both the operated extremity and the contralateral normal side. MRI assessment of the infrapatellar fat pad, quadriceps, sartorius, gracilis, semi-membranosus muscles and biceps muscles was also carried out. The correlation between the changes in skeletal muscle mass, the volume of the infrapatellar fat pad and the alterations in the DP-TT distances and P-PT angles were analysed.

RESULTS

The quadriceps muscle cross-sectional diameter had a mean of 157.2 mm(2) (115.6/319.5) in the operated extremity, and it was 193 mm(2) (77.6/282.2) in the non-operated normal side (p = 0.001). For the Gracilis muscle, the mean was 84.4 mm(2) (19.7/171) at the operated extremity and 75.7 mm(2) (26.9/238.2) on the normal side (p = 0.05). The cross-sectional areas of the semi-membranosus, sartorius and biceps muscles in the operated and non-operated extremity were not noticeably different (n.s). The P-PT angle was 153° (129.7/156.4) in the operated extremity and 145.7° (137.6/163.4) in the non-operated normal extremity (p < 0.05). While DP-TT distance was 11.4 mm (9.4/20.4) in the operated extremity, it was 14.1 mm (7.3/17.1) in the non-operated extremity (p = 0.001). The correlation analyses revealed that the quadriceps hypotrophy negatively correlated (r = -0.4, p = 0.02) with the P-PT angle but positively correlated with the increase in gracilis muscle volume (r = 0.4, p = 0.03).

CONCLUSION

This study revealed that patellofemoral joint kinematics in the operated extremity was diminished in the sagittal plane correlating with the quadriceps muscle volume loss and gracilis muscle hypertrophy. The modalities focused on both preventing and treating the hypotrophy of the quadriceps muscle following the surgical treatment of tibial fracture, which may help to overcome this quite common pathology.

KINESIO TAPING NÃO ALTERA A RELAÇÃO EMG ENTRE VASTO LATERAL E VASTO MEDIAL DURANTE MEIO-AGACHAMENTO

RESUMO Introdução: Kinesio Taping é uma técnica realizada com aplicação de fitas elásticas sobre a pele, que se propõe a produzir determinados efeitos com fins de prevenção e tratamento das lesões musculoesqueléticas. No entanto, os meios pelos quais tais efeitos ocorrem continuam sendo investigados e discutidos, principalmente no que diz respeito à utilização no campo da reabilitação e do esporte. Objetivo: Analisar a relação da atividade eletromiográfica encontrada nos músculos vasto lateral (VL) e vasto medial (VM) em duas condições: sem aplicação de Kinesio Taping (GnKT) e com aplicação de Kinesio Taping (GKT) em uma população saudável, com experiência em treinamento de força. Métodos: Dezoito sujeitos do sexo masculino (idade: 28,1 ± 6,9 anos; massa corporal: 85,5 ± 8,3 kg; estatura: 179,5 ± 6,9 cm; comprimento de membro inferior: 97,0 ± 4,2 cm) realizaram o exercício de meio-agachamento livre, com velocidade controlada, sem e com aplicação de Kinesio Taping. A relação foi verificada pela proporção de magnitude de ativação (VM/VL), utilizando-se os valores de root mean square (RMS). A sequência para realização dos exercícios nas condições mencionadas foi randomizada e balanceada. Resultados: Os valores encontrados para a razão VM/VL na situação GnKT foram de 83,96 ± 5,79% para VM e 84,13 ± 7,16% para VL. Já na situação GKT, 84,55 ± 16,97% para VM e 80,53 ± 9,20% para VL. Não foram observadas diferenças significativas nos valores de RMS para a relação VM/VL submetidos a aplicação de Kinesio Taping. Conclusão: A aplicação de Kinesio Taping não demonstrou influenciar a relação da atividade eletromiográfica entre os músculos vasto lateral e vasto medial durante a execução do exercício de meio-agachamento.

Effect of blood flow restriction on tissue oxygenation during knee extension

PURPOSE

Time-resolved near-infrared spectroscopy was used to quantify tissue oxy- and deoxyhemoglobin concentrations ([HbO2] and [HbR]) and O2 saturation (stO2) in the oblique fibers of the vastus medialis muscle and brain prefrontal cortex during knee extension with and without blood flow restriction (BFR).

METHODS

Six young healthy males performed three sets of knee extensions on a dynamometer (50% one-repetition maximum) separated by 90-s rest periods in three conditions: 1) until fatigue without BFR (fatigue), 2) until fatigue with BFR (100 mm Hg cuff constriction around thigh (BFR)), 3) same number of repetitions from condition 2 without BFR (matched). Each condition was performed on a separate visit.

RESULTS

BFR was associated with higher [HbR] at the oblique fibers of the vastus medialis muscle (rest 1: 57.8 (BFR) vs 35.0 μM (matched); P < 0.0001) and a significantly lower stO2 during recovery periods between sets (7.5%-11.2 % lower than non-BFR conditions for rest 1 and 2, P < 0.0001). Using a piecewise linear spline method, a spike in [HbR] was observed before the onset of HbR clearance during recovery, causing HbR clearance to begin at a higher concentration (81 (BFR) vs 62 μM (matched), P = 0.029). [HbO2] kinetics during recovery were also affected by BFR, with longer duration (BFR, 51 s; matched, 31 s; P = 0.047) but lower rate of increase (BFR, 58 μM·min; matched, 89 μM·min; P = 0.004) during recovery. In the prefrontal cortex, BFR was associated with increased [HbR], diminished increase in [HbO2], and higher subjective exertion.

CONCLUSIONS

These findings yield insight into possible physiological mechanisms of BFR and suggest a role of time-resolved near-infrared spectroscopy in monitoring and optimization of BFR exercise on an individual basis.

Which patellofemoral joint imaging features are associated with patellofemoral pain? Systematic review and meta-analysis

OBJECTIVES

To review the association between patellofemoral joint (PFJ) imaging features and patellofemoral pain (PFP).

DESIGN

A systematic review of the literature from AMED, CiNAHL, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PEDro, EMBASE and SPORTDiscus was undertaken from their inception to September 2014. Studies were eligible if they used magnetic resonance imaging (MRI), computed tomography (CT), ultrasound (US) or X-ray (XR) to compare PFJ features between a PFP group and an asymptomatic control group in people <45 years of age. A pooled meta-analysis was conducted and data was interpreted using a best evidence synthesis.

RESULTS

Forty studies (all moderate to high quality) describing 1043 people with PFP and 839 controls were included. Two features were deemed to have a large standardised mean difference (SMD) based on meta-analysis: an increased MRI bisect offset at 0° knee flexion under load (0.99; 95% CI: 0.49, 1.49) and an increased CT congruence angle at 15° knee flexion, both under load (1.40 95% CI: 0.04, 2.76) and without load (1.24; 95% CI: 0.37, 2.12). A medium SMD was identified for MRI patella tilt and patellofemoral contact area. Limited evidence was found to support the association of other imaging features with PFP. A sensitivity analysis showed an increase in the SMD for patella bisect offset at 0° knee flexion (1.91; 95% CI: 1.31, 2.52) and patella tilt at 0° knee flexion (0.99; 95% CI: 0.47, 1.52) under full weight bearing.

CONCLUSION

Certain PFJ imaging features were associated with PFP. Future interventional strategies may be targeted at these features.

PROSPERO REGISTRATION NUMBER

CRD 42014009503.

Vastus medialis oblique and vastus lateralis activity during a double-leg semisquat with or without hip adduction in patients with patellofemoral pain syndrome

Background

The purpose was to investigate the effect of double-leg semisquat with hip adduction on the activation of vastus medialis oblique (VMO) and vastus lateralis (VL) in patients with patellofemoral pain syndrome (PFPS).

Methods

Thirty patients with PFPS were designated to the study group, while 30 healthy matched subjects were enrolled in the control group. The activation of VL and VMO was recorded with surface electromyography (EMG) during double-leg semisquat (DS) and double-leg semisquat with hip adduction (DS-HA). The time domain and frequency domain indexes of the electromyography data were collected for analysis.

Results

In the study group, the time domain indexes (RMS, IEMG) and frequency domain index (MPF) of VL were significant higher than VMO in the test of DS (P < 0.05); and the time domain of VMO was significantly higher in the test of DS-HA when compared to DS (P < 0.05) while there was no difference in the activation of VL.

Conclusions

In the study group, an increase in activity of the VMO was observed through the surface EMG signal in the double-leg semisquat exercise with hip adduction compared to the exercise without hip adduction. This finding indicates that VMO activation can be more selectively obtained through the exercise with hip adduction which can help balance the VL and VMO.