The relative timing of VMO and VL in the aetiology of anterior knee pain: a systematic review and meta-analysis

Lower extremity muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects

BACKGROUND

Previous studies mainly focused on muscles at the operated knee after anterior cruciate ligament reconstruction, less on muscles around other joints of the operated and non-operated leg. The aim of this study was to investigate muscle activation onset times during the transition from double-leg stance to single-leg stance in anterior cruciate ligament reconstructed subjects.

METHODS

Lower extremity muscle activation onset times of both legs of 20 fully returned to sport anterior cruciate ligament reconstructed subjects and 20 non-injured control subjects were measured during the transition from double-leg stance to single-leg stance in eyes open and eyes closed conditions. Analysis of covariance (ANCOVA) was used to evaluate differences between groups and differences between legs within both groups, while controlling for peak center of pressure velocity.

FINDINGS

Significantly delayed muscle activation onset times were found in the anterior cruciate ligament reconstructed group compared to the control group for gluteus maximus, gluteus medius, vastus medialis obliquus, medial hamstrings, lateral hamstrings and gastrocnemius in both eyes open and eyes closed conditions (P<.05). Within the anterior cruciate ligament reconstructed group, no significant different muscle activation onset times were found between the operated and non-operated leg (P>.05).

INTERPRETATION

Despite completion of rehabilitation and full return to sport, the anterior cruciate ligament reconstructed group showed neuromuscular control deficits that were not limited to the operated knee joint. Clinicians should focus on relearning multi-segmental anticipatory neuromuscular control strategies after anterior cruciate ligament reconstruction.

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.

The Use of Sonographically Guided Botulinum Toxin Type A (Dysport) Injections Into the Tensor Fasciae Latae for the Treatment of Lateral Patellofemoral Overload Syndrome

BACKGROUND

Pain in the anterior and lateral parts of the knee during exercise is a common clinical problem for which current management strategies are often unsuccessful.

PURPOSE

To investigate the effect of an ultrasound-guided botulinum toxin (BT) injection into the tensor fasciae latae (TFL), followed by physical therapy, in patients classified with lateral patellofemoral overload syndrome (LPOS) who failed to respond to conventional treatment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A total of 45 patients (mean ± SD age, 32.4 ± 8.6 years) who met the inclusion criteria of (1) activity-related anterolateral knee symptoms, (2) symptoms lasting longer than 3 months, (3) a pathological abnormality confirmed by magnetic resonance imaging, and (4) previous failed physical therapy received an ultrasound-guided injection of BT into the TFL followed by physical therapy. Patient-reported outcomes were collected at 5 intervals: before the injection; at 1, 4, and 12 weeks after the injection; and at a mean 5 years after the injection. In 42 patients, relative iliotibial band (ITB) length changes were assessed using the modified Ober test at the first 4 time points. A computational model was run to simulate the effect of TFL weakening on gluteus medius (GMed) activity. Statistical analysis was undertaken using 1-way analysis of variance and paired t tests with Bonferroni post hoc correction.

RESULTS

There was a significant improvement in Anterior Knee Pain Scale scores from before the injection (61 ± 15) to 1 (67 ± 15), 4 (70 ± 16), and 12 weeks (76 ± 16) after the injection and in 87% of patients (39/45 patients available for follow-up) at approximately 5 years (from 62.9 ± 15.4 to 87.0 ± 12.5) after the injection (all P < .010). A significant effect on the modified Ober test was identified as a result of the intervention, with an increase in leg drop found at 1 (3° ± 5°), 4 (4° ± 5°), and 12 (7° ± 6°) weeks after the injection compared with before the injection (all P < .010). Simulating a progressive reduction in TFL strength resulted in corresponding increases in GMed activity during gait.

CONCLUSION

An injection of BT into the TFL, combined with physical therapy, resulted in a significant improvement of symptoms in patients with LPOS, which was maintained at 5-year follow-up. This may result from reduced lateral TFL/ITB tension or to an increase in GMed activity in response to inhibition of the TFL.

The Effect of the Mulligan Knee Taping Technique on Patellofemoral Pain and Lower Limb Biomechanics

BACKGROUND

Patellofemoral pain (PFP) affects 25% of the general population, occurring 2 times more often in females compared with males. Taping is a valuable component of the management plan for altering lower limb biomechanics and providing pain relief; however, the effects of alternative taping techniques, such as Mulligan knee taping, appear yet to be researched.

PURPOSE

To determine whether the Mulligan knee taping technique altered levels of perceived knee pain and lower limb biomechanics during a single-legged squat (SLSq) in adult females with PFP.

STUDY DESIGN

Controlled laboratory study.

METHODS

A total of 20 female patients with PFP, aged 18 to 35 years, participated in this study. Participants performed 3 to 5 SLSq on their most symptomatic limb during a taped (Mulligan knee taping technique) and nontaped (control) condition. During the eccentric phase of the SLSq, the 3-dimensional kinematics (250 Hz) of the knee and hip and the ground-reaction forces (1000 Hz) and muscle activation patterns (1000 Hz) of the gluteus medius, vastus lateralis, and vastus medialis oblique were measured. Participants' perceived maximum knee pain was also recorded after the completion of each squat.

RESULTS

Between-condition differences were found for hip kinematics and gluteus medius activation but not for kinetics or vastus medialis oblique and vastus lateralis muscle activity (timing and activation). Compared with the nontaped condition, the Mulligan knee taping technique significantly (P = .001) reduced perceived pain during the SLSq (mean ± SD: 2.29 ± 1.79 and 1.29 ± 1.28, respectively). In the taped condition compared with the control, the onset timing of the gluteus medius occurred significantly earlier (120.6 ± 113.0 and 156.6 ± 91.6 ms, respectively; P = .023) and peak hip internal rotation was significantly reduced (6.38° ± 7.31° and 8.34° ± 7.92°, respectively; P = .002).

CONCLUSION

The Mulligan knee taping technique successfully reduced knee pain in participants with PFP. This is the first study to establish a link between Mulligan knee taping and the reduction of PFP in conjunction with decreased hip internal rotation and earlier activation of gluteus medius.

CLINICAL RELEVANCE

The Mulligan knee taping technique may benefit the clinical environment by providing an alternative evidence-based treatment plan for PFP.

Elmslie-Trillat, Maquet, Fulkerson, Roux Goldthwait, and Other Distal Realignment Procedures for the Management of Patellar Dislocation: Systematic Review and Quantitative Synthesis of the Literature

PURPOSE

To evaluate clinical outcomes, rate of recurrence, and complications following distal realignment procedures (Elmslie-Trillat, Maquet, Fulkerson, Roux Goldthwait, and other distal realignment procedures) performed alone or in combination with proximal procedures for the management of patellar dislocation.

METHODS

A systematic literature review was performed following the PRISMA guidelines (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). A search in PubMed, Medline, Cumulative Index to Nursing and Allied Health Literature (CINAHL), Cochrane, Embase, and Google Scholar databases using various combinations of the keywords "patellar," "dislocation," "tibial transfer," "Elmslie-Trillat," "Roux Goldthwait," "tibial tubercle osteotomy," "Fulkerson," "Maquet," "procedure," "clinical," and "outcome."

RESULTS

Thirty-eight articles were included in the systematic review. A total of 1,182 knees belonging to 1,023 patients were grouped according to the duration of the follow-up period. The overall rate of recurrence was 7% (83 of 1,182 knees). Approximately 5.3% (28 of 520 knees) of the redislocation occurred in the short-medium term, and 8.3% (55 of 662 knees) occurred in the long-term.

CONCLUSIONS

Distal realignment procedures performed alone or in combination with proximal procedures for the management of patellar dislocation have shown good clinical outcomes and a low rate of recurrence highlighting the efficacy of these procedures. To date no randomized controlled clinical trials are available on the topic.

LEVEL OF EVIDENCE

Level IV, systematic review of Level III and IV studies.

Immediate Effect of Patterned Electrical Neuromuscular Stimulation on Pain and Muscle Activation in Individuals With Patellofemoral Pain

CONTEXT

For individuals with patellofemoral pain (PFP), altered muscle activity and pain are common during functional tasks. Clinicians often seek interventions to improve muscle activity and reduce impairments. One intervention that has not been examined in great detail is electrical stimulation.

OBJECTIVE

To determine whether a single patterned electrical neuromuscular stimulation (PENS) treatment would alter muscle activity and pain in individuals with PFP during 2 functional tasks, a single-legged squat and a lateral step down.

DESIGN

Cohort study.

SETTING

Sports medicine research laboratory. PATIENTS OF OTHER PARTICIPANTS: A total of 22 individuals with PFP (15 women, 7 men; age = 26.0 ± 7.9 years, height = 173.8 ± 8.1 cm, mass = 75.1 ± 17.9 kg).

INTERVENTION(S)

Participants were randomized into 2 intervention groups: a 15-minute PENS treatment that produced a strong motor response or a 15-minute 1-mA subsensory (sham) treatment.

MAIN OUTCOME MEASURE(S)

Before and immediately after the intervention, we assessed normalized electromyography amplitude, percentage of activation time across functional tasks, and onset of activation for the vastus medialis oblique, vastus lateralis, gluteus medius, adductor longus, biceps femoris, and medial gastrocnemius muscles during a single-legged squat and a lateral step down. Scores on the visual analog scale for pain were recorded before and after the intervention.

RESULTS

After a single treatment of PENS, the percentage of gluteus medius activation increased (0.024) during the lateral step down. Visual analog scores decreased during both the single-legged squat (PENS: preintervention = 2.7 ± 1.9, postintervention = 0.9 ± 0.7; sham: preintervention = 3.2 ± 1.6, postintervention = 2.8 ± 1.9; group × time interaction: P = .041) and lateral step down (PENS: preintervention = 3.4 ± 2.4, postintervention = 1.1 ± 0.8; sham: preintervention = 3.9 ± 1.7, postintervention = 3.3 ± 2.0; group × time interaction: P = .023). No changes in electromyography or pain measures were noted in the sham group.

CONCLUSIONS

The PFP participants who received PENS had immediate improvement in gluteus medius activation and a reduction in pain during functional tasks.

Runners with patellofemoral pain have altered biomechanics which targeted interventions can modify: A systematic review and meta-analysis

Patellofemoral pain (PFP) is the most prevalent running pathology and associated with multi-level biomechanical factors. This systematic review aims to guide treatment and prevention of PFP by synthesising prospective, observational and intervention studies that measure clinical and biomechanical outcomes in symptomatic running populations. Medline, Web of Science and CINAHL were searched from inception to April 2015 for prospective, case-control or intervention studies in running-related PFP cohorts. Study methodological quality was scored by two independent raters using the modified Downs and Black or PEDro scales, with meta-analysis performed where appropriate. 28 studies were included. Very limited evidence indicates that increased peak hip adduction is a risk factor for PFP in female runners, supported by moderate evidence of a relationship between PFP and increased peak hip adduction, internal rotation and contralateral pelvic drop, as well as reduced peak hip flexion. Limited evidence was also identified that altered peak force and time to peak at foot level is a risk factor for PFP development. Limited evidence from intervention studies indicates that both running retraining and proximal strengthening exercise lead to favourable outcomes in both pain and function, but only running retraining significantly reduces peak hip adduction, suggesting a possible kinematic mechanism. Put together, these findings highlight limited but coherent evidence of altered biomechanics which interventions can alter with resultant symptom change in females with PFP. There is a clear need for high quality prospective studies of intervention efficacy with measurement of explanatory mechanisms.

Differentiating giant cell tumor of bone from patellofemoral syndrome: a case study

Balancing the assessment of musculoskeletal dysfunctions with a high level of suspicion for non-mechanical origins can be a challenge for the clinician examining a sports injury. Without timely diagnosis, non-mechanical complaints could result in surgery or loss of limb. This case describes the discovery of a Giant Cell Tumor of Bone (GCTB) following the re-evaluation of an athlete who had undergone five years of conservative management for patellofemoral pain syndrome (PFPS). Knee injuries account for 32.6% of sports injuries with PFPS being the most common and most likely diagnosis for anterior knee pain. GCTB is a benign aggressive bone tumor with a predilection for the juxta-articular region of the knee, comprising up to 23% of all benign bone tumors, and commonly occurs in the second to fourth decades. This case report illustrates the difficulty in accurately diagnosing healthy athletes, reviews common differentials for knee complaints and explores helpful diagnostic procedures.

The immediate effect of lumbopelvic manipulation on EMG of vasti and gluteus medius in athletes with patellofemoral pain syndrome: A randomized controlled trial

OBJECTIVE

To evaluate the immediate effect of lubmopelvic manipulation on EMG activity of vastus medialis, vastus lateralis and gluteus medius as well as pain and functional performance of athletes with patellofemoral pain syndrome.

DESIGN

Randomized placebo-controlled trial.

METHODS

Twenty eight athletes with patellofemoral pain syndrome were randomly assigned to two groups. One group received a lubmopelvic manipulation at the side of the involved knee while the other group received a sham manipulation. EMG activity of the vasti and gluteus medius were recorded before and after manipulation while performing a rocking on heel task. The functional abilities were evaluated using two tests: step-down and single-leg hop. Additionally, the pain intensity during the functional tests was assessed using a visual analog scale.

RESULTS

The onset and amplitude of EMG activity from vastus medialis and gluteus medius were, respectively, earlier and higher in the manipulation group compared to the sham group. There were no significant differences, however, between two groups in EMG onset of vastus lateralis. While the scores of one-leg hop test were similar for both groups, significant improvement was observed in step-down test and pain intensity in the manipulation group compared to the sham group.

CONCLUSIONS

Lubmopelvic manipulation might improve patellofemoral pain and functional level in athletes with patellofemoral pain syndrome. These effects could be due to the changes observed in EMG activity of gluteus medius and vasti muscles. Therefore, the lubmopelvic manipulation might be considered in the rehabilitation protocol of the athletes with patellofemoral pain syndrome.

Knee orthoses for treating patellofemoral pain syndrome

BACKGROUND

Patellofemoral pain syndrome (PFPS) is a painful musculoskeletal condition, which is characterised by knee pain located in the anterior aspect (front) and retropatellar region (behind) of the knee joint. Various non-operative interventions are suggested for the treatment of this condition. Knee orthoses (knee braces, sleeves, straps or bandages) are worn over the knee and are thought to help reduce knee pain. They can be used in isolation or in addition to other treatments such as exercise or non-steroidal anti-inflammatory medications.

OBJECTIVES

To assess the effects (benefits and harms) of knee orthoses (knee braces, sleeves, straps or bandages) for treating PFPS.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (11 May 2015), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015 Issue 5), MEDLINE (1946 to 8 May 2015), EMBASE (1980 to 2015 Week 18), SPORTDiscus (1985 to 11 May 2015), AMED (1985 to 8 May 2015), CINAHL (1937 to 11 May 2015), PEDro (1929 to June 2015), trial registries and conference proceedings.

SELECTION CRITERIA

Randomised and quasi-randomised controlled clinical trials evaluating knee orthoses for treating people with PFPS. Our primary outcomes were pain and function.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for eligibility, assessed study risk of bias and extracted data. We calculated mean differences (MD) or, where pooling data from different scales, standardised mean differences (SMD) with 95% confidence intervals (CI) for continuous outcomes and risk ratios (RR) with 95% CIs for binary outcomes. We pooled data using the fixed-effect model.

MAIN RESULTS

We included five trials (one of which was quasi-randomised) that reported results for 368 people who had PFPS. Participants were recruited from health clinics in three trials and were military recruits undergoing training in the other two trials. Although no trials recruited participants who were categorised as elite or professional athletes, military training does comprise intensive exercise regimens. All five trials were at high risk of bias, including performance bias reflecting the logistical problems in these trials of blinding of participants and care providers. As assessed using the GRADE approach, the available evidence for all reported outcomes is 'very low' quality. This means that we are very uncertain about the results.The trials covered three different types of comparison: knee orthosis and exercises versus exercises alone; one type of orthosis versus another; and knee orthosis versus exercises. No trials assessed the mode of knee orthosis use, such as whether the orthosis was worn all day or only during physical activity. Two trials had two groups; two trials had three groups; and one trial had four groups.All five trials compared a knee orthosis (knee sleeve, knee brace, or patellar strap) versus a 'no treatment' control group, with all participants receiving exercises, either through a military training programme or a home-based exercise programme. There is very low quality evidence of no clinically important differences between the two groups in short-term (2 to 12 weeks follow-up) knee pain based on the visual analogue scale (0 to 10 points; higher scores mean worse pain): MD -0.46 favouring knee orthoses, 95% CI -1.16 to 0.24; P = 0.19; 234 participants, 3 trials). A similar lack of clinically important difference was found for knee function (183 participants, 2 trials). None of the trials reported on quality of life measures, resource use or participant satisfaction. Although two trials reported on the impact on sporting or occupational participation, one trial (35 participants) did not provide data split by treatment group on the resumption of sport activity and the other reported only on abandonment of military training due to knee pain (both cases were allocated a knee orthosis). One trial (59 participants, 84 affected knees) recording only adverse events in the two knee orthoses (both were knee sleeves) groups, reported 16 knees (36% of 44 knees) had discomfort or skin abrasion.Three trials provided very low quality evidence on single comparisons of different types of knee orthoses: a knee brace versus a knee sleeve (63 participants), a patella strap with a knee sleeve (31 participants), and a knee sleeve with a patellar ring versus a knee sleeve only (44 knees). None of three trials found an important difference between the two types of knee orthosis in pain. One trial found no clinically important difference in function between a knee brace and a knee sleeve. None of the three trials reported on quality of life, resource use or participant satisfaction. One trial comparing a patella strap with a knee sleeve reported that both participants quitting military training due to knee pain were allocated a knee sleeve. One poorly reported trial found three times as many knees with adverse effects (discomfort or skin abrasion) in those given knee sleeves with a patella ring than those given knee sleeves only.One trial compared a knee orthosis (knee brace) with exercise (66 participants). It found very low quality evidence of no clinically important difference between the two intervention groups in pain or knee function. The trial did not report on quality of life, impact on sporting or occupational participation, resource use, participant satisfaction or complications.

AUTHORS' CONCLUSIONS

Overall, this review has found a lack of evidence to inform on the use of knee orthoses for treating PFPS. There is, however, very low quality evidence from clinically heterogeneous trials using different types of knee orthoses (knee brace, sleeve and strap) that using a knee orthosis did not reduce knee pain or improve knee function in the short term (under three months) in adults who were also undergoing an exercise programme for treating PFPS. This points to the need for good-quality clinically-relevant research to inform on the use of commonly-available knee orthoses for treating PFPS.

The Role of Botulinum Toxin Type A in the Clinical Management of Refractory Anterior Knee Pain

Anterior knee pain is a highly prevalent condition affecting largely young to middle aged adults. Symptoms can recur in more than two thirds of cases, often resulting in activity limitation and reduced participation in employment and recreational pursuits. Persistent anterior knee pain is difficult to treat and many individuals eventually consider a surgical intervention. Evidence for long term benefit of most conservative treatments or surgical approaches is currently lacking. Injection of Botulinum toxin type A to the distal region of vastus lateralis muscle causes a short term functional “denervation” which moderates the influence of vastus lateralis muscle on the knee extensor mechanism and increases the relative contribution of the vastus medialis muscle. Initial data suggest that, compared with other interventions for anterior knee pain, Botulinum toxin type A injection, in combination with an active exercise programme, can lead to sustained relief of symptoms, reduced health care utilisation and increased activity participation. The procedure is less invasive than surgical intervention, relatively easy to perform, and is time- and cost-effective. Further studies, including larger randomized placebo-controlled trials, are required to confirm the effectiveness of Botulinum toxin type A injection for anterior knee pain and to elaborate the possible mechanisms underpinning pain and symptom relief.

Atrophy of the Quadriceps Is Not Isolated to the Vastus Medialis Oblique in Individuals With Patellofemoral Pain

STUDY DESIGN

Cross-sectional. Objectives To determine if quadriceps atrophy was present in people with patellofemoral pain (PFP), and whether the vastus medialis oblique (VMO) was selectively involved.

BACKGROUND

Despite the lack of research investigating individual quadriceps muscle size in individuals with PFP, it has been suggested that selective atrophy of the VMO relative to the vastus lateralis could be associated with PFP.

METHODS

The quadriceps muscle sizes of 35 participants with PFP (22 with unilateral and 13 with bilateral symptoms) and 35 asymptomatic control participants matched for age and sex were measured using real-time ultrasound. The thicknesses of the VMO, vastus lateralis, vastus medialis, rectus femoris, and vastus intermedius were measured. Paired-samples t tests were used to compare muscle thickness between limbs in those with unilateral PFP, and independent t tests were used to compare muscle thickness between groups with and without PFP. Results In those with unilateral PFP, the thickness of all portions of the quadriceps muscle was statistically smaller in the symptomatic compared to the asymptomatic limb: VMO (P = .038), vastus medialis (P<.001), vastus lateralis (P = .005), vastus intermedius (P = .013), and rectus femoris (P = .045). No difference was found in thickness of any of the portions of the quadriceps on the affected side of people with PFP compared to asymptomatic controls: VMO (P = .148), vastus medialis (P = .474), vastus lateralis (P = .122), vastus intermedius (P = .466), and rectus femoris (P = .508).

CONCLUSION

Atrophy of all portions of the quadriceps muscles is present in the affected limb of people with unilateral PFP. There was no atrophy of the quadriceps in individuals with PFP compared to those without pathology. Selective atrophy of the VMO relative to the vastus lateralis was not identified in people with PFP.

Influence of step rate and quadriceps load distribution on patellofemoral cartilage contact pressures during running

Interventions used to treat patellofemoral pain in runners are often designed to alter patellofemoral mechanics. This study used a computational model to investigate the influence of two interventions, step rate manipulation and quadriceps strengthening, on patellofemoral contact pressures during running. Running mechanics were analyzed using a lower extremity musculoskeletal model that included a knee with six degree-of-freedom tibiofemoral and patellofemoral joints. An elastic foundation model was used to compute articular contact pressures. The lower extremity model was scaled to anthropometric dimensions of 22 healthy adults, who ran on an instrumented treadmill at 90%, 100% and 110% of their preferred step rate. Numerical optimization was then used to predict the muscle forces, secondary tibiofemoral kinematics and all patellofemoral kinematics that would generate the measured primary hip, knee and ankle joint accelerations. Mean and peak patella contact pressures reached 5.0 and 9.7MPa during the midstance phase of running. Increasing step rate by 10% significantly reduced mean contact pressures by 10.4% and contact area by 7.4%, but had small effects on lateral patellar translation and tilt. Enhancing vastus medialis strength did not substantially affect pressure magnitudes or lateral patellar translation, but did shift contact pressure medially toward the patellar median ridge. Thus, the model suggests that step rate tends to primarily modulate the magnitude of contact pressure and contact area, while vastus medialis strengthening has the potential to alter mediolateral pressure locations. These results are relevant to consider in the design of interventions used to prevent or treat patellofemoral pain in runners.

Muscle force cannot be directly inferred from muscle activation: illustrated by the proposed imbalance of force between the vastus medialis and vastus lateralis in people with patellofemoral pain

Muscle force cannot be directly inferred from neural drive assessed using electromyography (EMG). Although the limitations associated with inferring force from EMG are well known, this has received little attention in the clinical literature. This commentary discusses these limitations within the context of the imbalance of force production between the vastus medialis (VM) and vastus lateralis (VL) muscles, which has been speculated to contribute to the development and/or persistence of patellofemoral pain. The balance of neural drive between vasti muscles is most frequently measured with 2 approaches: (1) the onset of VM EMG relative to that of the VL, and (2) the ratio of the EMG signal amplitude of the VM and VL. Here, we demonstrate that this classical approach cannot determine whether an imbalance of force exists between the VM and VL. Considerations such as altered electromechanical delay (time between the onsets of muscle activation and patellar motion) in people with patellofemoral pain may lead to a reconsideration of the classical interpretation of the onset of VM EMG signal relative to that of the VL. Also, beyond the amplitude of the neural drive, muscle force depends on several biomechanical factors (eg, specific tension and physiological cross-sectional area). Therefore, the VL/VM activation ratio does not provide information about the VL/VM force ratio, which is ultimately the most important information from a clinical perspective. Although the literature includes defenses for both the existence and absence of this force imbalance in people with patellofemoral pain, a reconsideration of the methods used to assess this imbalance is needed.

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.

Comparison of frequency and time domain electromyography parameters in women with patellofemoral pain

BACKGROUND

Despite its high incidence, patellofemoral pain etiology remains unclear. No prior study has compared surface electromyography frequency domain parameters and surface electromyography time domain variables, which have been used as a classic analysis of patellofemoral pain.

METHODS

Thirty one women with patellofemoral pain and twenty eight pain-free women were recruited. Each participant was asked to descend a seven step staircase and data from five successful trials were collected. During the task, the vastus medialis and vastus lateralis muscle activities were monitored by surface electromyography. The data were processed and analyzed in four variables of the frequency domain (median frequency, low, medium and high frequency bands) and three time domain variables (Automatic, Cross-correlation and Visual Onset between the vastus medialis and vastus lateralis muscles). Reliability, Receiver Operating Characteristic curves and regression models were performed.

FINDINGS

The medium frequency band was the most reliable variable and different between the groups for both muscles, also demonstrated the best values of sensitivity and sensibility, 72% and 69% for the vastus medialis and 68% and 62% for the vastus lateralis, respectively. The frequency variables predicted the pain of individuals with patellofemoral pain, 26% for the vastus medialis and 20% for the vastus lateralis, being better than the time variables, which achieved only 7%.

INTERPRETATION

The frequency domain parameters presented greater reliability, diagnostic accuracy and capacity to predict pain than the time domain variables during stair descent and might be a useful tool to diagnose individuals with patellofemoral pain.

Strengthening of the hip and core versus knee muscles for the treatment of patellofemoral pain: a multicenter randomized controlled trial

CONTEXT

Patellofemoral pain (PFP) is the most common injury in running and jumping athletes. Randomized controlled trials suggest that incorporating hip and core strengthening (HIP) with knee-focused rehabilitation (KNEE) improves PFP outcomes. However, no randomized controlled trials have, to our knowledge, directly compared HIP and KNEE programs.

OBJECTIVE

To compare PFP pain, function, hip- and knee-muscle strength, and core endurance between KNEE and HIP protocols after 6 weeks of rehabilitation. We hypothesized greater improvements in (1) pain and function, (2) hip strength and core endurance for patients with PFP involved in the HIP protocol, and (3) knee strength for patients involved in the KNEE protocol.

DESIGN

Randomized controlled clinical trial.

SETTING

Four clinical research laboratories in Calgary, Alberta; Chicago, Illinois; Milwaukee, Wisconsin; and Augusta, Georgia.

PATIENTS OR OTHER PARTICIPANTS

Of 721 patients with PFP screened, 199 (27.6%) met the inclusion criteria (66 men [31.2%], 133 women [66.8%], age = 29.0 ± 7.1 years, height = 170.4 ± 9.4 cm, weight = 67.6 ± 13.5 kg).

INTERVENTION(S)

Patients with PFP were randomly assigned to a 6-week KNEE or HIP protocol.

MAIN OUTCOME MEASURE(S)

Primary variables were self-reported visual analog scale and Anterior Knee Pain Scale measures, which were conducted weekly. Secondary variables were muscle strength and core endurance measured at baseline and at 6 weeks.

RESULTS

Compared with baseline, both the visual analog scale and the Anterior Knee Pain Scale improved for patients with PFP in both the HIP and KNEE protocols (P < .001), but the visual analog scale scores for those in the HIP protocol were reduced 1 week earlier than in the KNEE group. Both groups increased in strength (P < .001), but those in the HIP protocol gained more in hip-abductor (P = .01) and -extensor (P = .01) strength and posterior core endurance (P = .05) compared with the KNEE group.

CONCLUSIONS

Both the HIP and KNEE rehabilitation protocols produced improvements in PFP, function, and strength over 6 weeks. Although outcomes were similar, the HIP protocol resulted in earlier resolution of pain and greater overall gains in strength compared with the KNEE protocol.

The immediate effects of foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in individuals with patellofemoral pain

BACKGROUND

Evidence shows that anti-pronating foot orthoses improve patellofemoral pain, but there is a paucity of evidence concerning mechanisms. We investigated the immediate effects of prefabricated foot orthoses on (i) hip and knee kinematics; (ii) electromyography variables of vastus medialis oblique, vastus lateralis and gluteus medius during a functional step-up task, and (iii) associated clinical measures.

METHODS

Hip muscle activity and kinematics were measured during a step-up task with and without an anti-pronating foot orthoses, in people (n=20, 9 M, 11 F) with patellofemoral pain. Additionally, we measured knee function, foot posture index, isometric hip abductor and knee extensor strength and weight-bearing ankle dorsiflexion.

FINDINGS

Reduced hip adduction (0.82°, P=0.01), knee internal rotation (0.46°, P=0.03), and decreased gluteus medius peak amplitude (0.9mV, P=0.043) were observed after ground contact in the 'with orthoses' condition. With the addition of orthoses, a more pronated foot posture correlated with earlier vastus medialis oblique onset (r=-0.51, P=0.02) whilst higher Kujala scores correlated with earlier gluteus medius onset (r=0.52, P=0.02).

INTERPRETATION

Although small in magnitude, reductions in hip adduction, knee internal rotation and gluteus medius amplitude observed immediately following orthoses application during a task that commonly aggravates symptoms, offer a potential mechanism for their effectiveness in patellofemoral pain management. Given the potential for cumulative effects of weight bearing repetitions completed with a foot orthoses, for example during repeated stair ascent, the differences are likely to be clinically meaningful.

Holistic approach to understanding anterior knee pain. Clinical implications

Anterior knee pain is one of the most frequent reasons for consultation within knee conditions. The aetiology is not well known, which explains the sometimes unpredictable results of its treatment. Normally, when we see a patient in the office with anterior knee pain, we only study and focus on the knee. If we do this, we are making a big mistake. We must not forget to evaluate the pelvis and proximal femur, as well as the psychological factors that modulate the course of the illness. Both the pelvifemoral dysfunction as well as the psychological factors (anxiety, depression, catastrophization and kinesiophobia) must be included in our therapeutic targets of the multidisciplinary treatment of anterior knee pain. We must not only focus on the knee, we must remember to "look up" to fully understand what is happening and be able to solve this difficult problem. The aetiology of anterior knee pain is multifactorial. Therefore, diagnosis and treatment of patellofemoral disorders must be individualized. Our findings stress the importance of tailoring physiotherapy, surgery and psycho-educational interventions to each patient.

Anterior knee pain after a total knee arthroplasty: What can cause this pain?

Total Knee Arthroplasty has been shown to be a successful procedure for treating patients with osteoarthritis, and yet approximately 5%-10% of patients experience residual pain, especially in the anterior part of the knee. Many theories have been proposed to explain the etiology of this anterior knee pain (AKP) but, despite improvements having been made, AKP remains a problem. AKP can be described as retropatellar or peripatellar pain, which limits patients in their everyday lives. Patients suffering from AKP experience difficulty in standing up from a chair, walking up and down stairs and riding a bicycle. The question asked was: “How can a ‘perfectly’ placed total knee arthroplasty (TKA) still be painful: what can cause this pain?”. To prevent AKP after TKA it is important to first identify the different anatomical structures that can cause this pain. Greater attention to and understanding of AKP should lead to significant pain relief and greater overall patient satisfaction after TKA. This article is a review of what pain is, how nerve signalling works and what is thought to cause Anterior Knee Pain after a Total Knee Arthroplasty.

The effect of anti-pronation foot orthoses on hip and knee kinematics and muscle activity during a functional step-up task in healthy individuals: a laboratory study

BACKGROUND

Greater frontal and transverse plane hip and knee motion, and delayed gluteus medius and vastus medialis oblique activation have frequently been identified in patellofemoral pain syndrome populations, whilst prefabricated anti-pronation foot orthoses have been reported to reduce symptoms. The aim of the study was to evaluate the effects of such orthoses on hip and knee kinematics, gluteal and vasti muscle activity, kinematic and electromyographic interactions alongside correlations with specific clinical measures.

METHODS

Eighteen asymptomatic individuals (11 male 7 female) had measures taken of static foot posture and ankle range of motion. Hip muscle activity and kinematics were measured using electromyography and an active motion capture system during a step-up task. Order of testing with or without orthoses was determined using a coin toss.

FINDINGS

Between condition paired t-tests indicated significantly reduced peak hip adduction angles (1.56°, P < 0.05) and significantly reduced knee internal rotation (1.3°, P < 0.05) in the orthoses condition. Reduced ankle dorsiflexion range of motion correlated with a reduction in hip adduction following the orthoses intervention (r = 0.59, P = 0.013).

INTERPRETATION

The effects of prefabricated orthoses may be partially explained by kinematic alterations that occur proximal to the foot in the kinetic chain. These clinically and biomechanically relevant effects appear more evident in those with reduced underlying ankle motion. Further research is indicated using a symptomatic population to explore the clinical relevance of these observations.

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.

Anterior knee pain after total knee arthroplasty: a narrative review

Anterior knee pain is one of the most common causes of persistent problems after implantation of a total knee replacement. It can occur in patients with or without patellar resurfacing. As a result of the surgical procedure itself many changes can occur which may affect the delicate interplay of the joint partners in the patello-femoral joint. Functional causes of anterior knee pain can be distinguished from mechanical causes. The functional causes concern disorders of inter- and intramuscular coordination, which can be attributed to preoperative osteoarthritis. Research about anterior knee pain has shown that not only the thigh muscles but also the hip and trunk stabilising muscles may be responsible for the development of a dynamic valgus malalignment. Dynamic valgus may be a causative factor for patellar maltracking. The mechanical causes of patello-femoral problems after knee replacement can be distinguished according to whether they increase instability in the joint, increase joint pressure or whether they affect the muscular lever arms. These causes include offset errors, oversizing, rotational errors of femoral or tibial component, instability, maltracking and chondrolysis, patella baja and aseptic loosening. In these cases, reoperation or revision is often necessary.

The contemporary management of anterior knee pain and patellofemoral instability

In this review the evidence for the management of patients with patellofemoral disorders is presented confined to anterior knee pain and patellar dislocation (excluding patellofemoral arthritis). Patients present along a spectrum of these two problems and are best managed with both problems considered. The key to managing these patients is by improving muscle function, the patient losing weight (if overweight), and judicious use of analgesics if pain is an important feature. Hypermobility syndrome should always be looked for since this is a prognostic indicator for a poor operative outcome. Operations should be reserved for those with correctable anatomical abnormalities that have failed conservative therapy. The current dominant operation is a medial patellofemoral ligament reconstruction.

Clinical and electromyographic results of proximal and distal realignment procedures in young patients with recurrent patellar dislocations

BACKGROUND

Until now, no study has been published about the electromyographic changes in the extensor apparatus after the Green procedure for proximal realignment in young patients with recurrent patellar dislocations. This electromyographic study was performed to analyze imbalances between the vastus medialis and vastus lateralis muscles after different patellar realignment procedures.

HYPOTHESIS

Surgical proximal realignment leads to electromyographic changes in the extensor apparatus of the knee and to imbalances between the vastus medialis and vastus lateralis muscles.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 28 knees of 25 patients, with a mean age of 15 years, were treated operatively for recurrent patellar dislocations. The mean follow-up was 6.3 years. Depending on the type of surgical intervention, the patients were assigned to 3 different groups: the patients of group 1 underwent only the Green vastus medialis obliquus (VMO) advancement, group 2 was treated with a combination of the Green proximal and the Roux-Goldthwait distal realignment, and group 3 was treated with a combination of the Green proximal realignment and an additional tubercle transfer. All patients underwent clinical, radiological, and electromyographic examinations. The muscle activities of a healthy control group without patellar dislocations were used for comparison.

RESULTS

A combination of the Green procedure and tubercle transfer led to significantly better clinical results and a lower number of redislocations (P < .05) compared with patients who underwent only the Green proximal realignment. While ascending or descending stairs, the ratio between the electromyographic activities of the vastus medialis and vastus lateralis muscles in groups 1 and 2 was significantly smaller compared with the control group (P < .02). Only the electromyograms of group 3 revealed a balanced extensor apparatus during loading with comparable activities of the vastus medialis and vastus lateralis muscles and no significant difference to the control group (P = .37).

CONCLUSION

Our electromyographic investigations showed the importance of the vastus medialis in the pathogenesis of malalignment of the extensor mechanism. The Green VMO advancement without tibial tubercle transfer is not able to balance the activities of the vastus medialis and vastus lateralis muscles and cannot be recommended for further use.

Shear wave elastography properties of vastus lateralis and vastus medialis obliquus muscles in normal subjects and female patients with patellofemoral pain syndrome

OBJECTIVE

The aim of our study was to define and compare the mechanical properties of the vastus lateralis (VL) and vastus medialis obliquus muscles (VMO) by the way of quantitative shear-wave elastography in male and female healthy control (HC) subjects, and in female patients with patellofemoral pain syndrome (PFPS).

MATERIALS AND METHODS

Twenty-two healthy volunteers (11 male and 11 female) and 11 female patients with anterior knee pain were included in the study. The SWE examinations for VL and VMO were performed while the subjects were performing open kinetic chain exercises in neutral and 30° hip abduction. The contraction capacity (CC) and contraction ratio (CR) values were determined in resting and contraction phases in both hip positions.

RESULTS

The mean elasticity values in the CC for VL and VMO muscles were significantly higher in male HC subjects when compared to female HC subjects (p < 0.05). The CR of the VL muscle in female patients with PFPS was not significantly different than the female HC group. The CR for the VMO muscle was significantly lower in female patients with PFPS when compared to female HC subjects (p < 0.05).

CONCLUSIONS

We found a significant VMO weakness, and this method may provide quantitative data that might influence the diagnosis of muscle weakness, in female patients with PFPS.

Expanding Panjabi's stability model to express movement: a theoretical model

Novel theoretical models of movement have historically inspired the creation of new methods for the application of human movement. The landmark theoretical model of spinal stability by Panjabi in 1992 led to the creation of an exercise approach to spinal stability. This approach however was later challenged, most significantly due to a lack of favourable clinical effect. The concepts explored in this paper address and consider the deficiencies of Panjabi's model then propose an evolution and expansion from a special model of stability to a general one of movement. It is proposed that two body-wide symbiotic elements are present within all movement systems, stability and mobility. The justification for this is derived from the observable clinical environment. It is clinically recognised that these two elements are present and identifiable throughout the body in different joints and muscles, and the neural conduction system. In order to generalise the Panjabi model of stability to include and illustrate movement, a matching parallel mobility system with the same subsystems was conceptually created. In this expanded theoretical model, the new mobility system is placed beside the existing stability system and subsystems. The ability of both stability and mobility systems to work in harmony will subsequently determine the quality of movement. Conversely, malfunction of either system, or their subsystems, will deleteriously affect all other subsystems and consequently overall movement quality. For this reason, in the rehabilitation exercise environment, focus should be placed on the simultaneous involvement of both the stability and mobility systems. It is suggested that the individual's relevant functional harmonious movements should be challenged at the highest possible level without pain or discomfort. It is anticipated that this conceptual expansion of the theoretical model of stability to one with the symbiotic inclusion of mobility, will provide new understandings on human movement. The use of this model may provide a universal system for body movement analysis and understanding musculoskeletal disorders. In turn, this may lead to a simple categorisation system alluding to the functional face-value of a wide range of commonly used passive, active or combined musculoskeletal interventions. Further research is required to investigate the mechanisms that enable or interfere with harmonious body movements. Such work may then potentially lead to new and evolved evidence based interventions.

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.

Influence of infrapatellar and suprapatellar straps on quadriceps muscle activity and onset timing during the body-weight squat

The use of knee braces for the treatment of patellofemoral pain syndrome (PFPS) is widely documented, yet the mechanism by which such braces alleviate knee pain remains unclear. This study attempted to clarify this issue by simplifying the brace to the level of only straps. The effectiveness of an infrapatellar strap for PFPS remains controversial, and the use of a suprapatellar strap has not yet been studied. Quadriceps muscle activity and onset timing parameters were measured with surface electromyography (EMG) during a body-weight squat in 19 healthy subjects during 4 different knee-strapping conditions (infra, supra, both, and none). No differences in normalized mean or peak EMG activity in any part of the quadriceps were found. The onset timing of the vastus lateralis (VL) was significantly delayed when using an infrapatellar strap (p < 0.05) or both straps (p < 0.05) and marginally delayed when using a suprapatellar strap (p < 0.10) in comparison with the no-strap (control) condition. No differences in the vastus medialis oblique (VMO) onset timing or VMO-VL onset timing difference were found among the strapping conditions, although an improvement in timing was noted with the suprapatellar condition. The results provide novel evidence that the application of an infrapatellar strap, suprapatellar strap, or both straps improves quadriceps muscle timing imbalances by delaying VL onset. Because the largest delay in VL onset occurred when wearing both straps, the combined application of an infrapatellar and suprapatellar strap may be the most beneficial in managing patellofemoral pain. Knee straps, unlike braces, are cost effective, nonrestrictive, and can be universally fitted to any knee and based on the results deserve further study in the patellofemoral pain population.

Electromechanical delay of the vastus medialis obliquus and vastus lateralis in individuals with patellofemoral pain syndrome

STUDY DESIGN

Case-control study.

OBJECTIVE

To examine electromechanical delay (EMD) of the vastus medialis obliquus (VMO) and the vastus lateralis (VL) in individuals with patellofemoral pain syndrome (PFPS).

BACKGROUND

EMD is a mechanical property of muscles related to protective reflex and sports performance. The time duration of the EMD can be shortened with strength training and, conversely, can be lengthened secondary to immobilization. However, it is unclear if EMD between various components of the quadriceps is affected in individuals with PFPS.

METHODS

Twenty-six individuals with PFPS and 26 healthy volunteers were studied. The VMO and VL were electrically stimulated to evoke muscle twitches. Ultrasound was used to assess patellar movement elicited by the muscle twitch. The time from the onset of electrical stimulation to the onset of patellar movement was measured as the EMD. The EMDs of the VMO and VL were compared between groups using a mixed-model analysis of variance.

RESULTS

Subsequent to a significant interaction (P<.001), post hoc analysis indicated that the EMD of the VMO was longer (PFPS, 37.3 ± 0.7 milliseconds; control, 25.9 ± 0.7 milliseconds; P<.001) and the EMD of the VL was shorter (PFPS, 18.4 ± 0.5 milliseconds; control, 25.1 ± 0.5 milliseconds; P<.001) in the PFPS group. Therefore, in the individuals with PFPS, the EMD of the VMO was significantly longer than that of the VL (P<.001), which was not the case for those in the control group (P = .20).

CONCLUSION

The mechanical properties of the VMO and VL may be altered in patients with PFPS.J Orthop Sports Phys Ther 2012;42(9):791-796, Epub 2 August 2012. doi:10.2519/jospt.2012.3973.

Quadriceps volumes are reduced in people with patellofemoral joint osteoarthritis

OBJECTIVES

This study aimed to (1) compare the volumes of vastus medialis (VM), vastus lateralis (VL), vastus intermedius and rectus femoris and the ratio of VM/VL volumes between asymptomatic controls and patellofemoral joint osteoarthritis (PFJ OA) participants; and (2) assess the relationships between cross-sectional area (CSA) and volumes of the VM and VL in individuals with and without PFJ OA.

METHODS

Twenty-two participants with PFJ OA and 11 controls aged ≥ 40 years were recruited from the community and practitioner referrals. Muscle volumes of individual quadriceps components were measured from thigh magnetic resonance (MR) images. The CSA of the VM and lateralis were measured at 10 equally distributed levels (femoral condyles to lesser femoral trochanter).

RESULTS

PFJ OA individuals had smaller normalized VM (mean difference 0.90 cm(3) · kg(-1), α = 0.011), VL (1.50 cm(3) · kg(-1), α = 0.012) and rectus femoris (0.71 cm(3) · kg(-1), α = 0.009) volumes than controls. No differences in the VM/VL ratio were observed. The CSA at the third level (controls) and fourth level (PFJ OA) above the femoral condyles best predicted VM volume, whereas the VL volume was best predicted by the CSA at the seventh level (controls) and sixth level (PFJ OA) above the femoral condyles.

CONCLUSION

Reduced quadriceps muscle volume was a feature of PFJ OA. Muscle volume could be predicted from CSA measurements at specific levels in PFJ OA patients and controls.

The non-operative treatment of anterior knee pain

Anterior knee pain is a common presenting complaint, and in many cases no identifiable cause can be found. In these circumstances it is commonly known as anterior knee pain syndrome or patellofemoral pain syndrome. The management for this condition is most commonly non-operative. Treatment strategies include physiotherapy, pharmacotherapy, orthoses and combinations of the above. There are many described methods in the literature with a wide spectrum of outcomes, which in itself is testimony to the lack of any generally accepted gold standard of care for these patients. It is thus unclear to the health care professional treating these patients which is the best treatment to offer. In this review we aim to summarise historical and most up to date literature on the subject and in so doing allow the health care professional pick whichever treatment strategy they feel most beneficial and also provide a guide for appropriate patient education.

Risk factors for patellofemoral pain syndrome: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVES

To systematically outline the risk factors for patellofemoral pain syndrome (PFPS).

BACKGROUND

PFPS is the most commonly diagnosed condition in young individuals with knee complaints. High incidence among athletes suggests a possibility of prevention. The first step toward prevention is identification of possible risk factors.

METHODS

Prospective studies that included 20 or more patients with PFPS and examined at least 1 possible risk factor for PFPS were included. An assessment list was applied to evaluate the quality of the studies. A meta-analysis was conducted using a random-effects model. Significant differences were based on calculated mean differences, with matching 95% confidence intervals (CIs). For dichotomous data, odds ratios or relative risks were calculated.

RESULTS

Of the 3845 potentially relevant articles, 7 were included in this review. These studies examined a total of 135 variables, and pooling was possible for 13 potential risk factors. The pooled data showed that knee extension peak torques were significantly lower in the PFPS group than in controls. Mean differences in torque, with negative differences reflecting lower means in the PFPS group, were as follows: (a) standardized relative to body weight at 60°/s, -0.24 Nm (95% CI: -0.39, -0.09); (b) standardized relative to body weight at 240°/s, -0.11 Nm (95% CI: -0.17, -0.05); (c) standardized relative to body mass index at 60°/s, -0.84 Nm (95% CI: -1.23, -0.44); (d) standardized relative to body mass index at 240°/s, -0.32 Nm (95% CI: -0.52, -0.12); (e) nonstandardized in a concentric mode at 60°/s, -17.54 Nm (95% CI: -25.53, -9.54); (f) nonstandardized in a concentric mode at 240°/s, -7.72 Nm (95% CI: -12.67, -2.77).

CONCLUSION

Weaker knee extension strength, expressed by peak torque, appears to be a risk factor for PFPS, based on meta-analyses of pooled results from multiple studies. Because several other risk factors for PFPS were described only in single studies, these additional risk factors, as well as those with conflicting evidence, need to be confirmed in future studies.

LEVEL OF EVIDENCE

Prognosis, level 1a-.

Neuromuscular function during stair descent in meniscectomized patients and controls

PURPOSE

The aim of this study was to identify differences in knee range of motion (ROM), movement speed, ground reaction forces (GRF) profile, neuromuscular activity, and muscle coactivation during the transition between stair descent and level walking in meniscectomized patients at high risk of knee osteoarthritis (OA) compared with the nonoperated leg and with healthy controls.

METHODS

A total of 22 meniscectomized patients (15 men and 7 women (mean±SD), 45.4±5.1 yr, 174.3±7.1 cm, 77.3±15.4 kg) and 26 healthy controls (16 men and 10 women, 45.6±6.1 yr, 174.9±8.1 cm, 78.6±16.8 kg) were tested using synchronous force plate, goniometer, and EMG recording (vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), semitendinosus (ST)) during the transition step between stair descent and level walking. Pain was assessed using the Knee Injury and Osteoarthritis Outcome Score.

RESULTS

Patients reported more pain than controls (P≤0.001), but no differences were observed between patients and controls in any variables including knee ROM during stance (operated leg=42.9°, nonoperated leg=44.3°, controls=43.4°, respectively, P=0.42). A shorter stance phase (Tstance; 657 vs 679 ms) was observed for the meniscectomized leg versus the nonoperated leg in patients along with reduced overall medial versus lateral thigh muscle activity in the meniscectomized leg during the weight acceptance phase (P≤0.05) and at peak GRF (P≤0.01).

CONCLUSIONS

Patients and controls did not differ in any of the examined variables. However, kinematic differences were observed in the meniscectomized leg compared with the nonoperated leg along with attenuated medial leg muscle activity in the meniscectomized leg. The present findings support the hypothesis that meniscectomized individuals demonstrate early modulations in kinematics and neuromuscular activity that may represent an initial phase in the development of knee OA.

An electromyographic exploratory study comparing the difference in the onset of hamstring and quadriceps contraction in patients with anterior knee pain

Idiopathic anterior knee pain in teenagers and young adults is a common condition. Patellar maltracking has been considered as a causative factor. The aim of our study was to investigate whether there was a difference in the timing of electromyographic (EMG) activity in the medial and lateral hamstring and quadriceps muscles of patients with anterior knee pain compared to asymptomatic control participants. This was a cross sectional observational study measuring EMG activation patterns. Two groups of participants were tested, one patient (mean age 15 years, n = 20) and one asymptomatic control (mean age 16 years, n = 17). Surface EMG (sampling rate 1000 Hz) was recorded from vastus medialis obliqus, vastus lateralis, and the medial and lateral hamstrings during three repetitions of maximal voluntary isometric contractions. The relative timing of the medial and lateral quadriceps and hamstrings was evaluated. The mean (95% confidence interval) difference between the groups in the lateral-medial hamstring onset timing was 53.8(1.9 to 105.6)ms during the maximal contraction. An independent t test showed that this difference was statistically significant (p = 0.043). The differences between the groups in the relative VMO to VL onset did not reach statistical significance. The results of this study suggest that the lateral hamstrings contract significantly earlier in patients with AKP compared to healthy controls for this small cohort. This altered activation pattern could produce external rotation of the tibia on the femur and cause lateral patella tracking.

Enduring efficacy of Botulinum toxin type A injection for refractory anterior knee pain

PURPOSE

To examine long-term outcomes of Botulinum toxin type A (BoNT-A) injection to vastus lateralis (VL) for refractory anterior knee pain (AKP).

METHODS

Two cohorts (private clinic referrals and previous research participants) injected with BoNT-A for AKP by one neurologist were surveyed retrospectively. Primary outcomes were self-reported benefit, duration of symptom relief, and knee surgery post-injection. Secondary outcomes were changes in utilization of medication/physiotherapy treatment, AKP symptoms and activity limitation.

RESULTS

Overall, average symptom duration was 76 months (SD 98). Responses were available from 46 of 53 private patients. Thirty-eight reported benefit from injection, which was ongoing in 29. Average benefit was 25 months (SD 21). Nine individuals reported symptom recurrence after an average of 14 months (SD 21). Ten had knee surgery post-injection; six of whom had not benefitted from BoNT-A injection. Nineteen of 23 previous research participants were contactable. Initially, all responded favorably to injection. Symptomatic benefit, with an average duration of 44 months (SD 20), persisted in 15. Two subjects proceeded to surgical intervention.

CONCLUSIONS

A single BoNT-A treatment to VL led initially to improved function and relief of knee-related symptoms in 57 of 65 individuals. Improvements were sustained at follow-up, with an average benefit of 34 months (SD 25) post-injection, in 44 of 57 cases.

The effect of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral contact pressure during simulated partial weight-bearing knee flexion

PURPOSE

The purpose of this in vitro study was to investigate the influence of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral pressure.

METHODS

A dynamic muscle-loaded knee squat was simulated on eight knee specimens with an upright knee simulator while measuring tibiofemoral joint kinematics and patellofemoral pressure distribution. The quadriceps muscle was attached to three actuators simulating the three main extensor muscles, and five different quadriceps loading patterns were tested.

RESULTS

Tibial axial and varus-valgus-rotation are affected most while changing quadriceps loading patterns from lateral to medial. Higher internal tibial rotation is associated with higher medial muscle load compared to the symmetrical loading condition. Contact force, contact area and maximum peak pressure rise with increasing flexion angles. Accentuating the vastus lateralis muscle induces a significant reduction in patellofemoral contact force and a 30% diminished contact area at 90° of flexion.

CONCLUSION

Strengthening the vastus medialis muscle leads to increased internal tibial rotation, thus optimizing patella tracking by lowering the Q-angle. In contrast, weakness of the vastus medialis muscle causes decreased tibial internal rotation and is associated with lower patellofemoral contact pressure and contact area. Vastus medialis exercise is advisable to improve patella tracking but may not be recommended in patients with disorders due to increased patellofemoral contact pressure.

Patellar maltracking correlates with vastus medialis activation delay in patellofemoral pain patients

BACKGROUND

Delayed onset of vastus medialis (VM) activity compared with vastus lateralis activity is a reported cause for patellofemoral pain. The delayed onset of VM activity in patellofemoral pain patients likely causes an imbalance in muscle forces and lateral maltracking of the patella; however, evidence relating VM activation delay to patellar maltracking is sparse. The aim of this study was to investigate the relationship between VM activation delay and patellar maltracking measures in pain-free controls and patellofemoral pain patients.

HYPOTHESIS

Patellar tilt and bisect offset, measures of patellar tracking, correlate with VM activation delay in patellofemoral pain patients classified as maltrackers.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

Vasti muscle activations were recorded in pain-free (n = 15) and patellofemoral pain (n = 40) participants during walking and jogging. All participants were scanned in an open-configuration magnetic resonance scanner in an upright weightbearing position to acquire the position of the patella with respect to the femur. Patellar tilt and bisect offset were measured, and patellofemoral pain participants were classified into normal tracking and maltracking groups.

RESULTS

Correlations between VM activation delay and patellar maltracking measures were statistically significant in only the patellofemoral pain participants classified as maltrackers with both abnormal tilt and abnormal bisect offset (R(2) = .89, P < .001, with patellar tilt during walking; R(2) = .75, P = .012, with bisect offset during jogging). There were no differences between the means of activation delays in pain-free and all patellofemoral pain participants during walking (P = .516) or jogging (P = .731).

CONCLUSION

There was a relationship between VM activation delay and patellar maltracking in the subgroup of patellofemoral pain participants classified as maltrackers with both abnormal tilt and abnormal bisect offset.

CLINICAL RELEVANCE

A clinical intervention such as VM retraining may be effective in only a subset of patellofemoral pain participants-namely, those with excessive tilt and excessive bisect offset measures. The results highlight the importance of appropriate classification of patellofemoral pain patients before selection of a clinical intervention.

Immediate effect and predictors of effectiveness of taping for patellofemoral pain syndrome: a prospective cohort study

BACKGROUND

Taping has been used to treat patellofemoral pain syndrome for more than 20 years, but its effectiveness is still controversial.

PURPOSE

This study was undertaken to investigate the effect and predictors of effectiveness of taping in the treatment of patellofemoral pain syndrome.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A total of 118 consecutive patients with patellofemoral pain syndrome were recruited; 100 of them completed this study. Patient sex, age, body mass index, Q angle, lateral patellar displacement, and lateral patellofemoral angle were recorded/measured. One therapist applied adhesive tape to each patient by the McConnell method. Patients scored their pain level on a 100-mm visual analog scale during stepping down from an 8-in platform, before and after taping. The change of score was evaluated by paired t test. Patients with a visual analog scale score decrease of 20 mm or more after taping were considered responsive, and the others were considered nonresponsive. The influences of the aforementioned factors, plus pretaping visual analog scale score, on the effectiveness of taping were analyzed by multivariate logistic regression.

RESULTS

The overall mean visual analog scale score decreased significantly after taping (from 49.0 to 29.3 mm; P < .001). There were 66 patients in the responsive group and 34 in nonresponsive group. Among the factors, body mass index, lateral patellofemoral angle, and Q angle were significant predictors of effectiveness. The responsive group had significantly smaller mean lateral patellofemoral angle, larger mean Q angle, and larger mean pretaping visual analog scale score than the nonresponsive group.

CONCLUSION

Taping was an effective treatment for patellofemoral pain syndrome, but was less effective in patients with higher body mass index, larger lateral patellofemoral angle, and smaller Q angle.