Quadriceps atrophy: to what extent does it exist in patellofemoral pain syndrome?

The Influence of the Q-Angle and Muscle Strength on Idiopathic Anterior Knee Pain in Adolescents

Background and Objectives: Idiopathic anterior knee pain is a common condition in adolescents and is mostly of unknown cause. The aim of this study was to examine the influence of the Q-angle and muscle strength on idiopathic anterior knee pain. Materials and Methods: Seventy-one adolescents (41 females and 30 males) diagnosed with anterior knee pain were included in this prospective study. The extensor strength in the knee joint and the Q-angle were monitored. The healthy extremity was used as a control. The Student's paired sample t-test was applied for testing the difference. Statistical significance was set at 0.05. Results: There was no statistically significant difference in the Q-angle value between the idiopathic AKP and the healthy extremity (p > 0.05) within the entire sample. A statistically significant higher Q-angle of the idiopathic AKP knee (p < 0.05) was obtained in the female subgroup. No statistically significant difference (p > 0.05) was found in the male subgroup. Within the male subgroup, the strength of the extensors within the knee joint of the healthy extremity had statistically significant higher values than the strength of these muscles in the affected extremity (p < 0.05). Conclusion: A greater Q-angle is a risk factor linked to anterior knee pain within the female population. Decreased muscle strength of knee joint extensors is a risk factor linked to anterior knee pain in both sex subgroups.

Quantification of sarcopenia in patients with rheumatoid arthritis by measuring the cross-sectional area of the thigh muscles with magnetic resonance imaging

PURPOSE

To determine the utility of cross-sectional area (CSA) measurements on magnetic resonance imaging (MRI), at the level of the thigh muscles, to estimate muscle mass in discriminating rheumatoid arthritis (RA) patients with sarcopenia from those without.

MATERIALS AND METHODS

Consecutive female RA patients were enrolled for this cross-sectional study. Patients were assessed for disease activity, radiological damage, handgrip strength, physical performance and for the presence of sarcopenia, identified in accordance with the EWGSOP2 criteria. A 1.5 T MRI machine was used to scan the thigh muscles. A dimensional region growth algorithm (Horos™) was used to segment the muscles CSAs (in cm²) on MR images located 25 cm above the knee joint (MRI-CSA-25). The MRI-CSA-25 was obtained by summing the CSAs of the individual muscles. MRI-CSA-25 was correlated (Pearson's r) with the other variables, and its optimal cut-off point (Youden index) for sarcopenia diagnosis was identified in relation to the EWGSOP2 criteria.

RESULTS

32 RA female patients were studied, 34.4% diagnosed as sarcopenic. The mean MRI-CSA-25 was 151.00 cm² for patient with sarcopenia, 275.57 cm² for patient without sarcopenia (p < 0.001). MRI-CSA-25 correlated significantly with measures of physical performance, and disease activity, but not with radiological damage or age. The MRI-CSA-25 optimal cut-off point in discriminating sarcopenic patients was identified at 182.00 cm² (AUC-ROC = 0.894).

CONCLUSION

MRI-CSA-25 can differentiate sarcopenic versus non-sarcopenic RA patients, representing an imaging biomarker of this condition.

Correlations of strength, proprioception, and tactile sensation to return-to-sports readiness among patients with anterior cruciate ligament reconstruction

Objectives: Anterior cruciate ligament reconstruction (ACLR) is the most common surgery for anterior cruciate ligament (ACL) injuries, and the relationships between patients' return to sports (RTS) readiness and different physical functions are inconclusive among patients with ACLR. This study aimed to investigate the correlations of strength, proprioception, and tactile sensation to the RTS readiness among patients with ACLR. Methods: Forty-two participants who received ACLR for at least 6 months were enrolled in this study. Their strength, proprioception, and tactile sensation were tested, and their RTS readiness was measured with the Knee Santy Athletic Return to Sports (K-STARTS) test, which consists of a psychological scale [Anterior Cruciate Ligament Return to Sports after Injury scale (ACL-RSI)] and seven functional tests. Partial correlations were used to determine their correlations while controlling for covariates (age, height, weight, and postoperative duration), and factor analysis and multivariable linear regressions were used to determine the degrees of correlation. Results: Knee extension strength was moderately correlated with K-STARTS total, ACL-RSI, and functional scores. Knee flexion strength, knee flexion and extension proprioception, and tactile sensation at the fifth metatarsal were moderately correlated with K-STARTS total and functional scores. Strength has higher levels of correlation with functional scores than proprioception. Conclusion: Rehabilitation to promote muscle strength, proprioception and tactile sensation should be performed among patients with ACLR, muscle strength has the highest priority, followed by proprioception, with tactile sensation making the least contribution.

Prospective comparative study between knee alignment-oriented static and dynamic balance exercise in patellofemoral pain syndrome patients with dynamic knee valgus

Exercise therapy has been reported as an effective treatment method for patellofemoral pain syndrome (PFPS). However, there is a lack of studies regarding the effectiveness of balance exercise in the treatment of patients with PFPS. This study aimed to prospectively compare changes in proprioception, neuromuscular control, knee muscle strength, and patient-reported outcomes between patients with PFPS treated with knee alignment-oriented static balance exercise (SBE) and dynamic balance exercise (DBE). The participants were divided into 2 groups: 17 knee alignment-oriented SBE group and 19 knee alignment-oriented DBE group. Proprioception was assessed by dynamic postural stability using postural stabilometry. Neuromuscular control and knee muscle strength were measured for acceleration time and peak torque in quadriceps muscle using an isokinetic device. Patient-reported outcomes were evaluated using a visual analog scale for pain and the Kujala Anterior Knee Pain Scale. There was greater improvement in dynamic postural stability (0.9 ± 0.3 vs 1.2 ± 0.5; 95% confidence interval [CI]: 0, 0.6; Effect size: 0.72; P = .021) and quadriceps AT (40.5 ± 14.3 vs 54.1 ± 16.9; 95% CI: 2.9, 24.2; Effect size: 0.86; P = .014) in the DBE group compared to the SBE group. Knee alignment-oriented DBE can be more effective in improving dynamic postural stability and quadriceps muscle reaction time compared with the knee alignment-oriented SBE in PFPS patients with dynamic knee valgus.

Effects of High-Intensity Aquatic or Bicycling Training in Athletes with Unilateral Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) is one of the most common overuse injuries experienced by athletes. It is characterized by pain and functional deficits that lead to decreased performance, thereby limiting sports activity. Therefore, optimal training interventions are required to improve physical fitness and function while minimizing pain due to PFPS. This study aimed to compare and analyze the effects of high-intensity aquatic training (AT) and bicycling training (BT) in male athletes with PFPS. Fifty-four athletes with PFPS were divided into AT and BT intervention groups. Intervention training was conducted three times per week for 8 weeks. Cardiorespiratory fitness was evaluated using the graded exercise test (GXT) based on peak oxygen uptake (VO₂ peak), and anaerobic threshold. For the knee strength test, extension and flexion were performed and measured using isokinetic equipment. One-leg hop tests and the Y-balance test (YBT) were performed to evaluate dynamic balance, and the International Knee Documentation Committee (IKDC) scoring system was used for subjective knee evaluation. The GXT, YBT, and IKDC scores were reported according to the group and duration of the intervention. After training, VO₂ peak, YBT, knee extension strength, and IKDC score improved significantly in both the AT and BT groups compared with the pre-training values. Furthermore, the AT group exhibited significant improvement compared with the BT group. We demonstrated that AT and BT effectively improved the symptoms and muscle strength of athletes with PFPS who were only able to engage in limited high-intensity field training. AT produced a modestly better effect than BT.

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.

Physical Examination and Patellofemoral Pain Syndrome: an Updated Review

PURPOSE OF REVIEW

Patellofemoral pain syndrome (PFPS) accounts for 25 to 40% of all knee disorders. Diagnosis of PFPS is primarily based on history and physical examination, but the findings on physical examination are often subtle and do not consistently correlate with symptoms described. Yoon and Fredericson published a review article in 2006 detailing the physical examination maneuvers most frequently used to assist clinicians in the accurate diagnosis and treatment of PFPS, and our aim in this review is to provide an update on this previous article focusing on the literature published over the past 15 years regarding the topic.

RECENT FINDINGS

Since publication of Fredericson's original review article, there have been studies building on the literature specifically surrounding Q angle, patellar tilt, crepitus, strength and functional testing, and physical examination maneuver clustering. Additionally, multiple studies have been conducted on the use of musculoskeletal ultrasound (US) as a diagnostic tool for PFPS. Recent literature has further supported Q angle (when measured utilizing a standardized protocol), crepitus, weakness of hip abductors and extensors, and weakness detected in functional testing as predictors of PFPS while finding inconsistent evidence behind lateral patellar tilt as a predictor of PFPS. The reliability of most physical examination tests alone remain low, but clustering physical examination findings may provide better sensitivities and specificities in diagnosing PFPS. Musculoskeletal US is rapidly gaining popularity, and decreased vastus medialis obliquus (VMO) volume, asymmetry in gluteus medius thickness, intra-articular effusions, and quadriceps and patellar tendon thicknesses have shown value in diagnosing those with PFPS. Additionally, US has the advantage of providing dynamic examination as well as evaluation of the patellofemoral joint in newborns and infants as a predictor of future patellofemoral instability. Further studies are needed to establish the gold standard for diagnosing PFPS and what US findings are truly predictive of PFPS.

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

INTRODUCTION

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

OBJECTIVE

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

DESIGN

A cross-sectional clinical study.

SETTING

An outpatient clinic of a tertiary care hospital.

PARTICIPANTS

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

INTERVENTIONS

No intervention.

MAIN OUTCOME MEASURES

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

RESULTS

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

CONCLUSIONS

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

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.

Static and Dynamic Quadriceps Stretching Exercises in Patients With Patellofemoral Pain: A Randomized Controlled Trial

BACKGROUND

Limited data are available on the effect of stretching exercise in patients with patellofemoral pain (PFP) who have inflexible quadriceps, which is one of the various causes of PFP syndrome. This study compares quadriceps flexibility, strength, muscle activation time, and patient-reported outcomes after static and dynamic quadriceps stretching exercises in patients with PFP who had inflexible quadriceps.

HYPOTHESIS

Quadriceps flexibility and strength, muscle activation time, and patient-reported outcomes would improve with dynamic quadriceps stretching as compared with static quadriceps stretching exercises.

STUDY DESIGN

Randomized controlled trial.

LEVEL OF EVIDENCE

Level 2.

METHODS

Of the 44 patients included in the study, 20 performed static stretching and 24 performed dynamic stretching. Quadriceps flexibility was assessed by measuring the knee flexion angle during knee flexion in the prone position (the Ely test). Muscle strength and muscle activation time were measured using an isokinetic device. The patient-reported outcomes were evaluated using the visual analogue scale for pain and anterior knee pain scale.

RESULTS

No significant differences in quadriceps flexibility and strength, muscle activation time, and patient-reported outcomes in the involved knees were found between the 2 groups (P values > 0.05).

CONCLUSION

Quadriceps flexibility and strength, muscle activation time, and patient-reported outcomes in patients with PFP who had inflexible quadriceps showed no significant differences between the static and dynamic quadriceps stretching exercise groups.

CLINICAL RELEVANCE

Both static and dynamic stretching exercises may be effective for improving pain and function in patients with PFP who have inflexible quadriceps.

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.

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.

Effects of Static and Dynamic Stretching With Strengthening Exercises in Patients With Patellofemoral Pain Who Have Inflexible Hamstrings: A Randomized Controlled Trial

BACKGROUND

Patellofemoral pain (PFP) syndrome is closely associated with muscle tightness. However, studies regarding the effects of stretching exercises on PFP patients with inflexible hamstrings are scarce. The aim of the study was to compare the effects between static and dynamic hamstring stretching in patients with PFP who have inflexible hamstrings.

HYPOTHESIS

Compared with static hamstring stretching, dynamic hamstring stretching will improve the parameters of hamstring flexibility, knee muscle strength, muscle activation time, and clinical outcomes in this patient population.

STUDY DESIGN

Prospective randomized controlled trial.

LEVEL OF EVIDENCE

Level 2.

METHODS

A total of 46 patients (25, static stretching; 21, dynamic stretching) participated. Hamstring flexibility was assessed according to the popliteal angle during active knee extension. Muscle strength and muscle activation time were measured using an isokinetic device. Clinical outcomes were evaluated using the visual analog scale (VAS) for pain and the anterior knee pain scale (AKPS).

RESULTS

There were no differences in hamstring flexibility and knee muscle strength of the affected knees between the groups (P > 0.05). Significantly improved muscle activation time and clinical outcomes of the affected knees were observed in the dynamic stretching group compared with the static stretching group (all Ps < 0.01 for hamstring, quadriceps, VAS, and AKPS).

CONCLUSION

In patients with PFP who have inflexible hamstrings, dynamic hamstring stretching with strengthening exercises was superior for improving muscle activation time and clinical outcomes compared with static hamstring stretching with strengthening exercises.

CLINICAL RELEVANCE

Clinicians and therapists could implement dynamic hamstring stretching to improve function and reduce pain in patients with PFP who have inflexible hamstrings.

Acute Effects of Open Kinetic Chain Exercise Versus Those of Closed Kinetic Chain Exercise on Quadriceps Muscle Thickness in Healthy Adults

This study aimed to compare immediate changes in the thickness of the rectus femoris (RF), vastus intermedius (VI), vastus lateralis (VL), vastus medialis (VM), and vastus medialis oblique (VMO) muscles after open kinetic chain exercise (OKCE) and closed kinetic chain exercise (CKCE) and identify the effect of both exercise types on each quadricep muscle for early rehabilitation to prevent knee joint injury. Twenty-six healthy participants (13 males and 13 females) were randomly divided into the OKCE (n = 13) and CKCE (n = 13) groups. The thickness of their quadriceps muscles was measured using a portable ultrasonic imaging device before and after exercise in the sequence RF, VI, VL, VM, and VMO. A two-way repeated measures analysis of variance was used to compare the thickness of each component of the quadriceps muscles between the two groups. The thickness of the RF, VL, VM, and VMO muscles increased after OKCE, and the thickness of the VI muscle showed the greatest increase with a medium–large effect size (F = 8.52, p = 0.01, and d = 0.53). The thickness of the VI, VL, VM, and VMO muscles increased after CKCE, and the VMO muscle had the largest effect size (F = 11.71, p = 0.00, and d = 1.02). These results indicate that the thickness of the quadriceps muscles can be selectively improved depending on the type of exercise.

Impaired Knee Muscle Capacity Is Correlated With Impaired Sagittal Kinematics During Jump Landing in Women With Patellofemoral Pain

Nunes, GS, Barton, CJ, and Serrão, FV. Impaired knee muscle capacity is correlated with impaired sagittal kinematics during jump landing in women with patellofemoral pain. J Strength Cond Res XX(X): 000-000, 2020-Knee and hip muscle capacity is impaired in women with patellofemoral pain (PFP), but little is known about the rate of force development (RFD) at the knee. Impaired muscle capacity may contribute to reduced sagittal plane movement at the knee and hip during jump landing in women with PFP. This study aimed to (a) compare knee extensor muscle capacity (including RFD), and hip abductor and extensor muscle capacity between women with and without PFP; and (b) evaluate the relationship between hip/knee muscle capacity and sagittal kinematics during single-legged drop jump landing in women with PFP. Fifty-two physically active women (26 with PFP and 26 controls) participated. Rate of force development (in %/ms), isometric, concentric, and eccentric torque (in N·m·kg × 100) were evaluated using isokinetic dynamometry, and knee and hip kinematics were evaluated using three-dimensional motion capture. Compared with the control group (CG), the PFP group (PFPG) presented lower isometric (12%, PFPG = 217.2 ± 46.0; CG = 246.5 ± 38.8; p = 0.02), concentric (21%, PFPG = 133.0 ± 42.6; CG = 169.2 ± 28.8; p < 0.01), and eccentric (17%, PFPG = 172.9 ± 56.7; CG = 208.4 ± 59.4; p = 0.03) knee extension torque; lower RFD until 30% (30%, PFPG = 0.57 ± 0.27; CG = 0.83 ± 0.37; p < 0.01) and 60% (31%, PFPG = 0.47 ± 0.24; CG = 0.67 ± 0.33; p = 0.01) of maximal isometric torque; and lower concentric hip abduction (13%, PFPG = 94.7 ± 19.1; CG = 108.4 ± 17.5; p = 0.01) and extension (17%, PFPG = 134.4 ± 34.3; CG = 162.6 ± 38.0; p < 0.01) torque. Significant correlations between reduced RFD for knee extension and reduced sagittal plane knee/hip range of motion during landing were identified (r = 0.39-0.49). In conclusion, women with PFP have impaired knee extensor isometric and dynamic strength, and RFD. Impaired knee extensor RFD is associated with a stiffer landing strategy (reduced movement).

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.

Ultrasound evaluation of the quadriceps muscles in pronated foot posture

OBJECTIVE

The main goal of this study was to investigate the size of all portions of the quadriceps muscles in individuals with pronated foot posture compared to normal foot posture using ultrasound imaging.

DESIGN

Twenty nine females with pronated foot posture and 29 age-, body weight-, body height-matched females with normal foot posture were recruited from university communities. The muscle thicknesses of the rectus femoris (RF), vastus medialis (VM), vastus medialis oblique (VMO), vastus lateralis (VL) and vastus intermedius (VI) were measured using ultrasound imaging.

RESULTS

The thicknesses of the RF and VMO were significantly smaller in individuals with pronated foot posture compared to normal foot posture (p<0.05). No significant differences were observed in the VM, VL, and VI muscle thicknesses in both groups.

CONCLUSION

Based on the results of the present study, it seems that besides the foot and lower leg muscles, an integrated assessment of proximal knee muscles, especially quadriceps, is required in individuals with pronated foot posture.

Alterations in energy consumption and plantar pressure distribution during walking in young adults with patellofemoral pain syndrome

OBJECTIVE

The aim of this study was to determine the alterations of walking energy expenditure and plantar pressure distribution in young adults with patellofemoral pain syndrome (PFPS).

METHODS

Thirty five individuals (mean age: 21.31 ± 1.76) with PFPS constituted the patient group and forty healthy participants (mean age: 21.40 ± 2.11) the control group. Preferred walking speeds (PWS) were determined on the over ground. Individuals walked on a treadmill for 7 min at their PWS and 30% above PWS and oxygen consumption was recorded via a metabolic analyzer. Net oxygen consumption was calculated for each walking trial. Borg scale was applied to assess perceived exertion during walking trial. Plantar pressure distributions were measured by a pedobarography device. Plantar area was subdivided into six zones to evaluate the dynamic plantar pressure data.

RESULTS

The mean PWS of PFPS and control groups were 4.69 ± 0.51 and 4.52 ± 0.60 km/h, respectively (p > .09). No significant difference was observed in energy expenditure during walking at PWS between 2 groups while oxygen consumption during 30% above PWS was higher in patient group (18.72 ± 3.75 and 16.64 ± 3.27) (p = .007). Net oxygen consumption was also found to be higher in PFPS group (15.12 ± 3.62 and 13.04 ± 3.24) (p = .005). The mean Borg scores were significantly higher in PFPS group at each walking trials (p < .001). No statistically significant difference was found between weight distribution (%) of symptomatic and nonsymptomatic extremity (50.45 ± 3.92% and 49.56 ± 3.93%, respectively) (p = .509). Dynamic pedobarography parameters were not different between 2 groups, and also between symptomatic and nonsymptomatic extremities (p > .05).

CONCLUSION

Although, rate of perceived exertion and energy expenditure during walking at 30% above PWS are affected negatively in young adults with PFPS, we may speculate that energy consumption and plantar pressure distribution can be compensated by a physiologic adaptation mechanism during walking at PWS.

LEVEL OF EVIDENCE

Level III, Therapeutic Study.

Effects of kinesio taping on neuromuscular performance and pain of individuals affected by patellofemoral pain: A randomized controlled trial

Patellofemoral pain (PFP) is one of the most frequent musculoskeletal dysfunctions in the knee and its treatment is controversial. This study analyzed the effects of Kinesio Taping (KT) immediately and 72 hours after its application on the electromyographic (EMG) activity of the vastus medialis oblique (VMO) muscle, on the isokinetic performance of the quadriceps femoris and on the pain of subjects with PFP. Fifty-four participants were divided into three groups and performed one of the following protocols: (1) control group (CG)-remained at rest; (2) KT tension group (TG)-KT application with tension in the VMO region; and (3) KT without tension group (WTG)-KT application without tension in the same region. VMO and vastus lateralis (VL) EMG activity (RMS and onset), isokinetic performance and pain intensity were evaluated at three moments: before KT application, immediately after and 72 hours after. A mixed model ANOVA was used for statistical analysis with a significance level of 5% (p ≤ 0.05). No differences between the evaluated groups were found in relation to EMG variables and isokinetic performance. A reduction in pain intensity was found in the WTG in comparison to CG, after 72 hours. KT does not alter EMG parameters nor the isokinetic performance of subjects with PFP. However, we noticed reduced pain in the group submitted to the technique without tension 72 hours after its application.

Is There a Biomechanical Link Between Patellofemoral Pain and Osteoarthritis? A Narrative Review

The patellofemoral (PF) joint is the knee compartment most commonly affected by osteoarthritis (OA). Even mild PF OA is associated with considerable pain and functional limitations. Despite its prevalence and impact, little is understood of the etiology or structural and functional features of PF OA. The clinical symptoms of PF OA, such as anterior knee pain during stair ambulation and squatting, share many similarities with PF pain in adolescents and young adults. PF joint OA is most commonly diagnosed in people aged >40 years, many of whom report a history of PF pain. As such, there is growing evidence that PF pain and PF OA form a continuum of disease. This review explores the possible relationship between the presence of PF pain and the development of PF OA. We review the evidence for altered neuromotor control and biomechanical factors that may be associated with altered PF loading in people with PF pain and PF OA. In doing so, we highlight similarities and differences that may evolve along the continuum. By improving our understanding of the neuromotor and biomechanical links between PF pain and PF OA, we may highlight potential targets for new rehabilitation strategies.

Female PFP patients present alterations in eccentric muscle activity but not the temporal order of activation of the vastus lateralis muscle during the single leg triple hop test

This study aimed to compare the concentric and eccentric activity and the temporal order of peak activity of the hip and knee muscles between women with patellofemoral pain (PFP) and healthy women during the single leg triple hop test (SLTHT). Electromyographic (EMG) and Kinematic data were collected from 14 healthy women (CG) and 14 women diagnosed with PFP (PFG) during a single session of the single leg triple hop test. Integral surface electromyography (iEMG) data of the hip and knee muscles in eccentric and concentric phases and the length of time that each muscle needed to reach the maximal peak of muscle activity were calculated. The iEMG in the eccentric phase was significantly higher (p < 0.05) than the concentric phase, for the gluteus maximus and gluteus medius muscles (CG and PFG) and for the vastus lateralis muscle (PFG). The vastus lateralis muscle was the first muscle to reach the highest peak of activity in the PFG, and the third to reach this peak in the CG. In the present study, the activity of the vastus lateralis muscle during the eccentric phase of the jump was greater than concentric phase, as a temporal anticipation of its peak in activity among women with PFP.

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.

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.

Impairment based rehabilitation for patellofemoral pain patients

Patellofemoral pain is a common knee pathology that affects a wide range of active individuals. These individuals often seek medical care, with 25% of all patients seen in sports medicine clinics being treated for patellofemoral pain. While conservative treatment produce beneficial short-term results, individuals with patellofemoral pain often have long-term pain and decreased quality of life for many years following their diagnosis. One of the challenges for treating this chronic condition is the heterogeneous presentation of impairments across patients, ranging from soft tissue restriction, muscle weakness, altered movement patterns during functional tasks, and weak core stability. Clinicians need to identify these impairments and develop an individualized impairment-based model for treating patients with PFP. The aim of this review it to provide guidance and recommendations for clinicians who treat PFP in hopes to improve long-term outcomes for the conservative treatment of PFP.

The relationship between quadriceps strength and joint position sense, functional outcome and painful activities in patellofemoral pain syndrome

PURPOSE

The aim of this study was to investigate how strongly the concentric and eccentric quadriceps strengths were correlated with the joint position sense, functional outcomes and painful activities in patients with patellofemoral pain syndrome (PFPS).

METHODS

The study included forty-six women diagnosed with unilateral PFPS. Eccentric and concentric quadriceps strengths were recorded at 60 and 180°/s. Active knee joint position sense (JPS) was measured at 20° and 60° of flexion. Functional levels were determined by using Kujala patellofemoral scores. Pain levels during stair descending and ascending, squatting and prolonged sitting were measured using 0-10 cm visual analogue scale. The relationship of isokinetic quadriceps strength with JPS results, Kujala score and pain levels were evaluated using Spearman's correlation coefficient test.

RESULTS

Eccentric and concentric quadriceps strengths were significantly lower on involved side than uninvolved side. JPS results were poorer on the painful knee when compared to uninvolved side. While eccentric strength correlated with both JPS target angles, concentric strength was correlated only with 20°. Both eccentric and concentric strengths were significantly correlated with Kujala scores and pain levels.

CONCLUSION

Quadriceps eccentric strength was correlated more to joint position sense than concentric strength. Both eccentric and concentric quadriceps strength related to pain and functional level in PFPS patients.

Correlation between quadriceps to hamstring ratio and functional outcomes in patellofemoral pain

BACKGROUND

The aim of this study was to investigate the correlation between quadriceps to hamstring (Q:H) ratio and the functional outcomes in Patellofemoral Pain (PFP) patients.

METHODS

The study included forty-four women diagnosed with unilateral PFP. Eccentric and concentric quadriceps and hamstring strength were recorded. Conventional Q:H ratio was calculated as the concentric quadriceps to concentric hamstring peak torque (Ratio 1). Functional ratios were calculated as the eccentric quadriceps to concentric hamstring peak torque (Ratio 2) and as the concentric quadriceps to eccentric hamstring torque (Ratio 3). Functional levels of the patients were determined by using Kujala scores, hop test and step test. Pain levels during activities were recorded. The relationship among Ratio 1, Ratio 2 and Ratio 3 with functional outcomes and pain levels were evaluated using Spearman's correlation coefficient test.

RESULTS

Eccentric and concentric quadriceps and hamstring strength were lower on involved side than uninvolved side. Ratio 2 correlated stronger with Kujala score (r=0.69) than Ratio 1 (r=0.49) and Ratio 3 (r=0.30). Step test (r=0.35) and hop test (r=0.38) only correlated with Ratio 2. Pain levels correlated more with Ratio 2 (r values ranged between 0.38 and 0.48).

CONCLUSION

Eccentric quadriceps to concentric hamstring ratio was observed more related to the functional outcomes and painful activities in patients with PFP.

LEVEL OF EVIDENCE III

Cross-sectional study.

Intra- and Inter-session Reliability of Static and Dynamic Postural Control in Participants with and without Patellofemoral Pain Syndrome

PURPOSE

To determine the intra- and inter-session reliability of balance performance in people with patellofemoral pain syndrome (PFPS) and matched controls.

METHODS

In this methodological study, single-leg-stance performance of 15 participants with unilateral PFPS and 15 healthy matched controls was assessed using the Biodex Balance System (BBS) under 4 task difficulty levels (static and dynamic, with and without visual feedback). Intra-class correlation coefficients (ICCs), standard errors of measurement, and coefficients of variation were calculated for the overall stability index, anterior-posterior stability index, and medial-lateral stability index.

RESULTS

Static and dynamic postural performance during single-leg stance showed moderate to very high reliability in the PFPS group (ICCs=0.53-0.96) and in healthy control participants (ICCs=0.51-0.91). Both measures were more reliable with eyes closed than with eyes open.

CONCLUSION

BBS stability indices appear to have acceptable reliability in people with PFPS, particularly in more challenging conditions, and may be incorporated into the evaluation and rehabilitation of this patient group.

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.

Effects of feedback on activation of the quadriceps during weight-bearing tasks of the Wii

[Purpose] This investigation evaluated the effect of real-time feedback on electrical activation of the quadriceps during 3 weight-bearing tasks of the Wii Fit Plus^®. [Subjects] Thirty male healthy volunteers were recruited. [Methods] Activation of the vastus medialis, vastus lateralis, and rectus femoris muscles was recorded during virtual lunge, single leg extension, and single leg reach exercises. Each exercise was performed twice in 3 randomized experimental conditions (with visual feedback, with auditory feedback, and with no feedback). The normalized electromyographic data (using maximum voluntary isometric contraction) were analyzed using repeated measures analysis of variance and Tukey’s test. [Results] No significant difference was found in the muscles among the feedback conditions during the 3 exercises. However, the variation in the muscle activity of the vastus medialis and vastus lateralis (18.23–29.20% of maximum voluntary isometric contraction) was higher (47–62%) than that in the rectus femoris (7.35–12.98% of maximum voluntary isometric contraction). [Conclusion] Real-time feedback did not alter quadriceps activation during the Wii tasks. Additionally, these games showed electromyographic activation levels similar to those for the same tasks outside the virtual environment. The Wii weight-bearing tasks could therefore constitute a physical activity program but without the additional benefit of feedback.

ELECTROMYOGRAPHIC ANALYSIS OF LEG EXTENSION EXERCISE DURING DIFFERENT ANKLE AND KNEE POSITIONS

The imbalance between vastus medialis oblique (VMO) and vastus lateralis (VL) strength is one of the main factor for patellofemoral pain syndrome (PFPS) onset, related to improper alignment of the patella. The aim of this paper is to investigate the effects of knee flexion, knee rotation and ankle flexion attitudes on the activity of the VMO and VL muscles during unilateral maximal voluntary isometric contraction (MIVC) of the quadriceps femoris. Eighteen healthy subjects volunteered for the study. Five conditions for two different knee flexion angles (90°; 30°) were tested using leg extension machine: Neutral (N) condition, maximal knee medial rotation (MR), maximal knee lateral rotation (LR), maximal ankle plantarflexion (PF) and maximal ankle dorsiflexion (DF). Data were normalized in order to calculate the normalized VMO/VL ratio. The normalized VMO/VL ratio for all the conditions occurred at 90° of knee flexion was higher than the same conditions at 30° of knee flexion (p = 0.02). No statistical differences between conditions at the same knee angle and for angle x condition interaction were observed (p > 0.05). These findings suggest that knee flexion should be the first variable to be managed during isometric knee extension movement performed by leg extension machine, in order to increase VMO/VL ratio.

Muscle activation features of the osteoarthritic knee with patellar lateral subluxation

OBJECTIVE

The aim of the study was to compare the muscle activation feature of vastus medialis obliquus (VMO) and vastus lateralis (VL) between the osteoarthritic knee patients with patellar lateral subluxation (Group 1B) and without patellar lateral subluxation (Group 1A).

METHODS

Isokinetic muscle strength of the knee extensor was evaluated using a CYBEX NORM dynamometer with angular velocities of 80, 120 and 240 degrees/second (°/sec) respectively, contraction activities of VMO and VL muscle were recorded with synchronized surface electromyography (sEMG). Age-matched healthy subjects were recruited and served as control group (Group 2). The VMO/VL ratio of EMG between Group 1A, Group 1B and Group 2 were compared.

RESULTS

The peak torque in Group A was 40.7 ± 12.9, in Group B was 39.6 ± 12.9 and in Group C was 60.2 ± 9.5 respectively at 80°/sec angular velocity (p < 0.01). There were no significant difference between Group 1A and Group 1B in the three trial of tested velocities (p > 0.01). The sEMG ratios of VMO/VL of Group 1B calculated at angular velocities of 80/sec was 0.769 ± 0.15, 120°/sec was 0.818 ± 0.22 and 240°/ sec was 0.850 ± 0.22, all those were lower than Group 1A and Group 2 (p<0.01).

CONCLUSION

Musculature imbalance of VMO and VL may explain the different muscle activation pattern in osteoarthritic knee patients with and without patellar lateral subluxation.

Effects of isometric exercise using biofeedback on maximum voluntary isometric contraction, pain, and muscle thickness in patients with knee osteoarthritis

[Purpose] The purpose of our study was to investigate the effects of isometric exercises using electromyographic biofeedback (EMGBF) and ultrasound biofeedback (USBF) on maximum voluntary isometric contraction (MVIC), pain assessed by the Visual Analogue Scale (VAS), and vastus medialis oblique (VMO) thickness in patients with knee osteoarthritis (OA). [Subjects and Methods] Thirty females over 65 years of age who had been diagnosed with knee osteoarthritis were recruited and randomly assigned to three groups, each comprising of 10 subjects. The Subjects in the EMGBF training and USBF training groups were trained with the corresponding physical training exercise program targeting the vastus medialis oblique, whereas the subjects in the control group were treated with conventional physical therapies, such as a hot pack, ultrasound, and transcutaneous electrical nerve stimulation. Subjects in each group were trained or treated for 20 min, 3 times a week for 8 weeks. [Results] The MVIC in the EMGBF and USBF training groups was significantly increased compared with that in the control group, and the VAS score (for measurement of pain) in the EMGBF and USBF training groups was significantly decreased compared with that in the control group. Only the EMGBF training group showed a significantly increased VMO thickness compared with before training. [Conclusion] These results suggest that USBF training is similar to EMGBF training in terms of its effectiveness and is helpful for treating patients with knee OA.

Cross-sectional area measurements versus volumetric assessment of the quadriceps femoris muscle in patients with anterior cruciate ligament reconstructions

OBJECTIVE

Our aim was to validate the use of cross-sectional area (CSA) measurements at multiple quadriceps muscle levels for estimating the total muscle volume (TMV), and to define the best correlating measurement level.

METHODS

Prospective institutional review board (IRB)-approved study with written informed patient consent. Thighs of thirty-four consecutive patients with ACL-reconstructions (men, 22; women, 12) were imaged at 1.5-T using three-dimensional (3D) spoiled dual gradient-echo sequences. CSA was measured at three levels: 15, 20, and 25 cm above the knee joint line. TMV was determined using dedicated volumetry software with semiautomatic segmentation. Pearson's correlation and regression analysis (including standard error of the estimate, SEE) was used to compare CSA and TMV.

RESULTS

The mean ± standard deviation (SD) for the CSA was 60.6 ± 12.8 cm(2) (range, 35.6-93.4 cm(2)), 71.1 ± 15.1 cm(2) (range, 42.5-108.9 cm(2)) and 74.2 ± 17.1 cm(2) (range, 40.9-115.9 cm(2)) for CSA-15, CSA-20 and CSA-25, respectively. The mean ± SD quadriceps' TMV was 1949 ± 533.7 cm(3) (range, 964.0-3283.0 cm(3)). Pearson correlation coefficient was r = 0.835 (p < 0.01), r = 0.906 (p < 0.01), and r = 0.956 (p < 0.01) for CSA-15, CSA-20 and CSA-25, respectively. Corresponding SEE, expressed as percentage of the TMV, were 15.2%, 11.6% and 8.1%, respectively.

CONCLUSION

The best correlation coefficient between quadriceps CSA and TMV was found for CSA-25, but its clinical application to estimate the TMV is limited by a relatively large SEE.

KEY POINTS

• Cross-sectional area was used to estimate QFM size in patients with ACL-reconstruction • A high correlation coefficient exists between quadriceps CSA and volume • Best correlation was seen 25 cm above the knee joint line • A relatively large standard error of the estimate limits CSA application.

Vastus medialis obliquus muscle morphology in primary and recurrent lateral patellar instability

The morphology of the vastus medialis obliquus (VMO) muscle in the anatomical setting of an unstable patella has not been described. Therefore, the purpose of this study was to investigate the morphological parameters of the VMO muscle that delineate its importance in the maintenance of patellofemoral joint stability. Eighty-two consecutive subjects were prospectively enrolled in this study. The groups were composed of thirty patients with an acute primary patellar dislocation, thirty patients with recurrent patellar dislocation, and twenty-two controls. Groups were adjusted according to sex, age, body mass index, and physical activity. Magnetic resonance imaging was used to measure the VMO cross-sectional area, muscle-fiber angulation, and the craniocaudal extent of the muscle in relation to the patella. No significant difference was found with respect to all measured VMO parameters between primary dislocation, recurrent dislocation, and control subjects with a trend noted for only the VMO cross-sectional area and the VMO muscle-fiber angulation. This finding is notable in that atrophy of the VMO has often been suggested to play an important role in the pathophysiology of an unstable patellofemoral joint.

Clinical and Functional Outcomes following Primary Repair versus Reconstruction of the Medial Patellofemoral Ligament for Recurrent Patellar Instability

Background. The purpose of this study was to compare outcomes of medial patellofemoral ligament (MPFL) repair or reconstruction. Methods. Fourteen knees that underwent MPFL repair and nine (F5, M4) knees that underwent reconstruction at our institution were evaluated for objective and subjective outcomes. The mean age at operation was 20.1 years for repair and 19.8 years for reconstruction. All patients had a minimum of 2 years of follow-up (range: 24-75 months). Patient subjective outcomes were obtained using the International Knee Documentation Committee (IKDC) and Kujala patellofemoral subjective evaluations, as well as Visual Analog (VAS) and Tegner Activity Scales. Bilateral isometric quadriceps strength and vastus medialis obliquus (VMO) and vastus lateralis (VL) surface EMG were measured during maximal isometric quadriceps contractions at 30° and 60° of flexion. Results. There were no redislocations in either group. There was no difference in IKDC (P = 0.16), Kujala (P = 0.43), Tegner (P = 0.12), or VAS (P = 0.05) scores at follow-up. There were no differences between repair and reconstruction in torque generation of the involved side at 30° (P = 0.96) and 60° (P = 0.99). In addition, there was no side to side difference in torque generation or surface EMG activation of VL or VMO. Conclusions. There were minimal differences found between patients undergoing MPFL repair and MPFL reconstruction for the objective and subjective evaluations in this study.

Future directions in painful knee osteoarthritis: harnessing complexity in a heterogeneous population

This perspective article proposes a conceptual model for the pain experience for individuals diagnosed with knee osteoarthritis (OA). Pain in knee OA is likely a heterogeneous, multifactorial phenomenon that involves not only the OA disease process but also elements specific to patient psychology and pain neurophysiology. The relevant contributions to the pain experience for any individual patient remain difficult, if not impossible, to definitively determine, and the rationale for many clinical treatment decisions arises primarily from a mechanistic understanding of OA pathophysiology. The Osteoarthritis Research Society International (OARSI) recently identified "phenotyping" of OA pain as a research priority to "better target pain therapies to individual patients." This perspective article proposes that contributions from 3 domains--knee pathology, psychological distress, and pain neurophysiology--should be considered equally important in future efforts to understand pain phenotypes in knee OA. Ultimately, characterization of pain phenotypes may aid in the understanding of the pain experience and the development of interventions specific to pain for individual patients.

Activities of the Vastus Lateralis and Vastus Medialis Oblique Muscles during Squats on Different Surfaces

[Purpose] The purpose of the present study was to examine the effects of squat exercises performed on different surfaces on the activity of the quadriceps femoris muscle in order to provide information on support surfaces for effective squat exercises. [Subjects and Method] Fourteen healthy subjects performed squat exercises for five seconds each on three different support surfaces: hard plates, foam, and rubber air discs. Their performance was measured using electromyography. As the subjects performed the squat exercises on each surface, data on the activity of the vastus medialis oblique and the vastus lateralis, and the vastus medials oblique/vastus lateralis ratio, were collected. [Results] The activity of the vastus medialis oblique and the vastus medialis oblique/vastus lateralis ratio were found to be statistically significantly higher on rubber air discs than when the squats were performed on hard plates or foam. [Conclusion] To activate the vastus medialis obilique, and to enhance the vastus medialis oblique/vastus lateralis ratio, unstable surfaces that are highly unstable should be selected.

Is there a relationship between tracking ability, joint position sense, and functional level in patellofemoral pain syndrome?

PURPOSE

This prospective cohort study investigated proprioception and motor control changes in patients with patellofemoral pain syndrome (PFPS), and how these changes related to knee function, pain, muscle strength and muscle endurance.

METHODS

The study included 43 women diagnosed with unilateral patellofemoral pain syndrome. Thirty-one healthy women were recruited as control group. Peak quadriceps femoris and hamstring muscle isokinetic torques were recorded at 60 and 180°/s. Joint position sense was tested by active reproduction of joint position during horizontal squat performance. Muscle coordination and motor control ability were tested by a multi-joint lower limb tracking-trajectory test. Muscle endurance was tested using a computerized functional squat system. Severity of pain in during stair ascent/descent, squatting, and prolonged sitting with knees 90° flexed were measured using a 10 category modified visual analogue scale. Functional levels of patients were determined using Kujala patellofemoral scores.

RESULTS

Active reproduction of joint position did not differ between PFPS and control groups. However, tracking-trajectory error was significantly higher in PFPS group than control subjects. Hamstring and quadriceps peak isokinetic torque and muscle endurance scores were significantly lower in the PFPS group. Kujala patellofemoral score displayed significant relationships with peak isokinetic quadriceps torque, knee pain, and joint position sense scores. Pain during stair descent, sitting, and quadriceps torque at 180°/s explained 57.7 % of the variation in Kujala patellofemoral score.

CONCLUSION

Although lower extremity joint position sense did not differ between groups, the PFPS group displayed a target-trajectory muscular coordination deficit, decreased muscular endurance, and decreased muscular strength compared to control group subjects. Pain level directly related to motor control performance while joint position sense scores did not. Knee pain and impaired strength related more to functional performance impairment than joint position sense scores in patients with PFPS.

Does quadriceps atrophy exist in individuals with patellofemoral pain? A systematic literature review with meta-analysis

STUDY DESIGN

Systematic literature review.

OBJECTIVES

To investigate whether quadriceps atrophy is present in the affected limb of individuals with patellofemoral pain (PFP).

BACKGROUND

PFP is a common condition. Atrophy of the quadriceps femoris, in particular the vastus medialis obliquus, is often assumed to be present by clinicians, and its resolution may underpin the reported effectiveness of quadriceps strengthening intervention in PFP rehabilitation.

METHODS

A systematic search of the literature was conducted to identify studies that measured the size of the quadriceps in individuals with PFP. Meta-analyses were performed to determine whether quadriceps size in limbs with PFP differed from that in comparison limbs. Separate meta-analyses were performed for quadriceps size measured as girth and quadriceps size measured with imaging (thickness, cross-sectional area, and volume).

RESULTS

Ten studies were included in this review. The meta-analysis of girth measurements (3 studies) found no atrophy in limbs with PFP (P = .638). The meta-analyses for imaging techniques (thickness, cross-sectional area, or volume measurements) showed atrophy in the limb with PFP compared to both the asymptomatic limb (3 studies) (P = .036) and limbs from a comparison group (3 studies) (P = .001). The single study that compared the vastus medialis obliquus and vastus lateralis in individuals with PFP found atrophy of both the vastus medialis obliquus and vastus lateralis but no significant difference in the amount of atrophy between them (P = .179).

CONCLUSION

Quadriceps muscle atrophy was shown to be present in PFP when analyzed by imaging, but not by girth measures. Insufficient data were available to determine if there was greater atrophy of the vastus medialis obliquus than the vastus lateralis. These findings support the rationale for use of quadriceps strengthening as part of a rehabilitation program for PFP.

Avaliação isocinética, dor e funcionalidade de sujeitos com síndrome da dor patelofemoral

Este estudo visou determinar a influência da Síndrome da Dor Patelofemoral (SDPF) sobre o pico de torque e trabalho da musculatura flexora e extensora do joelho, além de avaliar a dor e funcionalidade de sujeitos com a disfunção. Participaram 52 sujeitos do gênero feminino, 23 com SDPF e 29 clinicamente saudáveis similares em idade, estatura e massa corporal. A avaliação isocinética foi realizada no modo concêntrico para os flexores e extensores do joelho nas velocidades de 60 e 180°/s. Também foi aplicada a Escala Visual Numérica antes e após cada velocidade do teste isocinético e o questionário de Kujala. Os dados foram analisados pela estatística descritiva e inferencial (testes U de Mann-Whitney, Wilcoxon e t independente) com nível de significância de α=0,05. O Grupo com Síndrome da Dor Patelofemoral (GSDPF) apresentou menor pontuação (p=0,01) no questionário de Kujala (75,7±12,3 pontos) em relação ao Grupo Controle (GC) (100±0,0 pontos), além de menor pico de torque, tanto em 60 como 180°/s, dos flexores (0,82±0,24 Nm/kg; 0,51±0,22 Nm/kg) e extensores (1,85±0,48 Nm/kg; 1,13±0,44 Nm/kg) do joelho, bem como menor trabalho total dos extensores do joelho a 180°/s (6,46±2,54 J/kg) e 60°/s (9,42±3,27 J/kg). Além disso, foi observado aumento da dor do GSDPF após a avaliação isocinética a 180°/s (0,9 cm) e 60°/s (2,3 cm). Os resultados evidenciaram que sujeitos com SDPF possuem menor capacidade funcional e menor pico de torque e trabalho dos flexores e extensores do joelho, sugerindo que o fortalecimento desta musculatura deve ser considerado na reabilitação destes sujeitos.

Evaluation of electromyographic biofeedback for the quadriceps femoris: a systematic review

OBJECTIVE

To critically review evidence for the effectiveness of electromyographic biofeedback (EMGB) of the quadriceps femoris muscle in treating various knee conditions.

DATA SOURCES

Databases used to locate randomized controlled trials included PubMed (1980-2010), Cumulative Index of Nursing and Allied Health Literature (CINAHL, 1995-2007), Web of Science (1986-2010), SPORTDiscus (1990-2007), and Physiotherapy Evidence Database (PEDro). Key words were knee and biofeedback.

STUDY SELECTION

The criteria for selection were clinical randomized controlled trials in which EMGB of the quadriceps femoris was used for various knee conditions of musculoskeletal origin. Trials were excluded because of research designs other than randomized controlled trials, articles published in a non-English language, inclusion of healthy research participants, inability to identify EMGB as the source of clinical improvement, and lack of pain, functional outcome, or quadriceps torque as outcome measures.

DATA EXTRACTION

Twenty specific data points were abstracted from each clinical trial under the broad categories of attributes of the patient and injury, treatment variables for the EMGB group, treatment variables for the control group, and attributes of the research design.

DATA SYNTHESIS

Eight trials yielded a total of 319 participants with patellofemoral pain syndrome (n = 86), anterior cruciate ligament reconstruction (n = 52), arthroscopic surgery (n = 91), or osteoarthritis (n = 90). The average methodologic score of the included studies was 4.6/10 based on PEDro criteria. Pooled analyses demonstrated heterogeneity of the included studies, rendering the interpretation of the pooled data inappropriate. The EMGB appeared to benefit short-term postsurgical pain or quadriceps strength in 3 of 4 postsurgical investigations but was ineffective for chronic knee conditions such as patellofemoral pain and osteoarthritis in all 4 studies. Because the findings are based on limited data, caution is warranted until more randomized controlled trials are conducted to support or refute the general trends observed in this report.

A physiotherapy perspective of musculoskeletal imaging in sport

This paper presents a physiotherapy perspective on the role that imaging is now playing in the diagnosis and management of musculoskeletal and sporting injuries. Although the Royal College of Radiologists and the UK Chartered Society of Physiotherapy were founded in the latter part of the nineteenth century, it is 100 years later that developments in the UK NHS have led to increased roles for non-medical healthcare professionals and allied health professionals, such as physiotherapists, in an extended clinical role. Physiotherapists, perhaps because of their knowledge of clinical and applied anatomy, have keenly taken up the opportunities offered to request and interpret imaging in its various forms; the most commonly available are plain radiography, musculoskeletal ultrasound and MRI. This has meant taking formal courses under the auspices of universities with mentorship and tutoring within the clinical setting, which are part of a continuing professional development. The ability to request several forms of imaging has enhanced physiotherapy practice and has increased the appreciation of the responsibilities which accompany this new role.

Static balance in patients with patellofemoral pain syndrome

Background:

The relationship between one-leg static standing balance (OLSSB) and patellofemoral pain syndrome (PFPS) is unknown.

Hypothesis:

OLSSB decreases in patients with PFPS.

Design:

Prospective case series.

Methods:

Fifty-two women with unilateral PFPS were enrolled in this study. OLSSB was evaluated with a stabilometer. Q angle was measured with a lengthened-arm universal goniometer. Lower extremity alignment was analyzed with full-length standing anteroposterior teleroentgenograms. Quadriceps and hamstring strength was measured on an isokinetic dynamometer.

Results:

There were significant differences in OLSSB, Q angle, and strength of quadriceps and hamstring between the symptomatic and asymptomatic sides. There was a correlation between the strength of the quadriceps and hamstring and OLSSB, while there was no correlation between OLSSB and the severity of pain, lower extremity alignment, and Q angle on the symptomatic side.

Conclusions:

OLSSB and quadriceps and hamstring strength decreased and Q angle increased on the symptomatic side in PFPS patients. A relationship between OLSSB and pain, Q angle, and lower extremity alignment was not detected, while there was a correlation between the strength of the quadriceps and hamstring and OLSSB.

Clinical Relevance:

A quadriceps and hamstring strengthening may be beneficial to improve OLSSB in patients with PFPS.

Effect of eccentric isotonic quadriceps muscle exercises on patellofemoral pain syndrome: an exploratory pilot study

Purpose

There is a decrease in quadriceps muscle strength in subjects with patellofemoral pain syndrome. Various types of strengthening exercises of the quadriceps are done as part of its management, but the effect of isotonic eccentric quadriceps muscle exercises on patellofemoral pain syndrome has not been studied. Hence the aim of this exploratory pilot study was to evaluate the effect of eccentric quadriceps training in patients with patellofemoral pain.

Methods

Twenty patients (12 female and 8 male, mean ages, 27.50 +/- 6.6 years) with patellofemoral pain syndrome were treated. The eccentric training of the quadriceps was given using a Baltimore Therapeutic Equipment (BTE) Primus machine. The main outcome measures used were percentage time on target as shown by the BTE primus machine, SF-36 Health questionnaire and patellofemoral pain severity scale. Statistical analysis was performed using SPSS 13.

Results

All the outcome measures showed significant improvements (P<0.05). Percentage time on target improved with a mean difference of 23.6, the SF-36 questionnaire showed an improvement in physical component score, mental component score and bodily pain with a mean difference of 10.9, 2.6 and 29.2 respectively and pain score when taken using patellofemoral severity scale also improved with a mean difference of 3.4.

Conclusion

Isotonic eccentric training of quadriceps muscles was found to be effective in reducing pain and improving the functional status of patients with patellofemoral pain syndrome and can be suggested as part of the treatment.

Patellofemoral pain: proximal, distal, and local factors, 2nd International Research Retreat

Patellofemoral pain (PFP) is one of the most common lower extremity conditions seen in orthopaedic practice. The mission of the second International Patellofemoral Pain Research Retreat was to bring together scientists and clinicians from around the world who are conducting research aimed at understanding the factors that contribute to the development and, consequently, the treatment of PFP. The format of the 2.5-day retreat included 2 keynote presentations, interspersed with 6 podium and 4 poster sessions. An important element of the retreat was the development of consensus statements that summarized the state of the research in each of the 4 presentation categories. In this supplement, you will find the consensus documents from the meeting, as well as the keynote addresses, schedule, and platform and poster presentation abstracts.

How can we strengthen the quadriceps femoris in patients with patellofemoral pain syndrome?

PURPOSE

the aim of this article was to review the clinical approach of quadriceps strengthening programmes.

METHODS

a literature search was carried out from 1980 up to September 2011. Eligible studies were those that: (1) evaluated the patients with patellofemoral pain syndrome (not healthy or asymptomatic subjects) (2) examined the effect of kinetic chain exercises (3) examined the effect of weight-bearing exercises (4) compared the effect of the combined exercises programme in the treatment of patients with patellofemoral pain syndrome.

RESULTS AND CONCLUSION

patients with patellofemoral pain syndrome may tolerate a closed kinetic chain exercises programme better than open kinetic chain. Weight-bearing and non-weight-bearing quadriceps exercises can significantly improve subjective and clinical outcomes in patients with patellofemoral pain syndrome. Combining treatments as an initial approach to treating patellofemoral pain but developing individualized more functional, global treatments are essential.