Altered vastii recruitment when people with patellofemoral pain syndrome complete a postural task

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.

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.

Tempo de início da atividade elétrica dos estabilizadores patelares na marcha em sujeitos com e sem síndrome de dor femoropatelar

INTRODUÇÃO: A síndrome de dor femoropatelar (SDFP) é um problema comum que afeta uma em cada quatro pessoas. A alteração no tempo de ativação e a intensidade de contração dos músculos vasto medial oblíquo (VMO) e vasto lateral (VL) são consideradas fatores importantes na etiologia da SDFP. No entanto, existem poucos estudos sobre a função da porção oblíqua do vasto lateral (VLO) e nenhum sobre o tempo de ativação (onset) do VLO em atividades funcionais em sujeitos normais e com SDFP. OBJETIVO: Assim, o objetivo do estudo foi investigar o tempo de início de atividade eletromiográfica nos músculos VMO, VLO e VL longo (VLL) durante a marcha. MATERIAIS E MÉTODOS: A amostra foi formada por 15 sujeitos sem e 12 com SDFP. Dados eletromiográficos foram obtidos dos músculos VMO, VLL e VLO durante caminhada na esteira sem inclinação. A diferença relativa no onset (DRO) entre VMO-VLL e VMO-VLO foi determinada a partir da média de três passadas. RESULTADOS: Houve diferença entre os sujeitos com e sem SDFP em relação à DRO entre VMO-VLL. Nos sujeitos com SDFP, a ordem de início da atividade elétrica foi VLL seguida por VLO e após VMO. Nos indivíduos sem a patologia, a ordem foi diferente: primeiro VMO após VLO e, por último, VLL. CONCLUSÃO: Os achados sugerem que a ativação do VMO após o VLL poderia auxiliar no desenvolvimento e na manutenção da SDFP, enquanto o tempo de ativação do VLO possui menor participação.

Women with patellofemoral pain syndrome have quadriceps femoris volume and strength deficiency

PURPOSE

the aim of this study was to assess muscle torque, total volume, and cross-sectional area, and lower limb function of the quadriceps muscle in women with unilateral patellofemoral pain syndrome (PFPS).

METHODS

twenty-four women with unilateral patellofemoral pain participated in the study, with each subject acting as their own internal control by using the unaffected limb. quadriceps muscle torque was measured with the Isomed 2000. The total volume and cross-sectional area (CSA) of the quadriceps muscle were measured by using magnetic resonance imaging. Lower limb function was assessed by hop and step-down tests.

RESULTS

there was a significant difference in the total volume (P < 0.05) and in the cross-sectional area (P < 0.05) of the quadriceps muscle between affected and unaffected sides. There was a significant difference in the peak torque of the quadriceps muscle at 60°/s between affected and unaffected sides (P < 0.05). There were significant correlations between quadriceps largest CSA and volume on the affected side (P < 0.05) and on the unaffected side (P < 0.05). There were significant negative correlations between the smallest CSA and the peak torque at 180°/s (P < 0.05) and at 60°/s (P < 0.05) on the affected side.

CONCLUSIONS

decreased torque, total volume, and CSA of the quadriceps muscle are presented in unilateral with PFPS although cause or effect cannot be established. Large prospective longitudinal studies are needed to detect the changes in the muscle structure and to establish whether these features are a cause of PFPS.

The female athlete

Over time, women have become more extensively involved in athletic programs. The female athlete presents a unique challenge to sports medicine in general. Although specific types of injuries are the same as in the male athlete, the female athlete is at higher risk for some of these injuries. Injuries may be sport specific, but gender-related injuries are also related to morphologic and physiologic differences between the male and female athlete. This article reviews some of the differences between the male and female athlete and focuses on a few prominent injuries or risks related specifically to the woman athlete.

Augmented low dye taping changes muscle activation patterns and plantar pressure during treadmill running

STUDY DESIGN

Randomized, crossover study.

OBJECTIVE

To examine changes in muscle activity and plantar pressure during running with the application of augmented low Dye (ALD) taping.

BACKGROUND

ALD taping is used clinically as part of management for lower limb injury. As of yet, no studies have examined the effect of this taping method on muscle activity and plantar pressure during running, simultaneously.

METHODS

Thirteen healthy recreational runners(mean ± SD age, 31.7 ± 4.9 years; height, 181.7 ± 4.6 cm; body mass, 81.6 ± 5.9 kg) completed a 6-minute run on a treadmill at a speed of 10 km·h⁻¹, with 3 different taping conditions (ALD, control tape, no tape), applied in randomized order. Peak and average EMG signal amplitude, onset time, and burst duration were calculated for the vastus medialis, vastus lateralis, and the gluteus medius. In-shoe plantar pressures were also recorded. All data were calculated based on an average of 20 steps collected after 5 minutes of treadmill running.

RESULTS

ALD taping significantly altered muscle activity and plantar pressure during treadmill running by (1) delaying the onset of the EMG signal of the gluteus medius, vastus medialis, and vastus lateralis, and (2) increasing lateral midfoot plantar pressure.

CONCLUSION

ALD taping significantly alters plantar pressure and muscle activation patterns during treadmill running. These findings give insight into the neuromuscular effect of a taping procedure that is used commonly in a clinical setting.

The efficacy of foot orthoses in the treatment of individuals with patellofemoral pain syndrome: a systematic review

Patellofemoral pain syndrome (PFPS) is a highly prevalent condition, often reducing functional performance and being linked to osteoarthritis development later in life. Prescribing foot orthoses is often advocated, although the link between foot mechanics and PFPS development remains unclear. This systematic review was conducted to summarize and critique the existing evidence for the efficacy of foot orthoses in individuals with PFPS and to provide guidance for future research evaluating foot orthoses in individuals with PFPS. A comprehensive search of MEDLINE, EMBASE, CINAHL and Current Contents revealed 138 citations for review. Two of the authors independently reviewed and assessed each citation for inclusion and quality using a modified version of the quality assessment scale for randomized controlled trials in PFPS designed by Bizzini and colleagues. A total of seven studies were included in the final review. The review found limited evidence that prefabricated foot orthoses may reduce the range of transverse plane knee rotation and provide greater short-term improvements in individuals with PFPS compared with flat inserts. Findings also indicated that combining physiotherapy with prefabricated foot orthoses may be superior to prefabricated foot orthoses alone. Further research is now needed to establish the mechanisms behind the efficacy of foot orthoses and to identify individuals with PFPS who are most likely to benefit from prescription of foot orthoses. A comparison of the efficacy between prefabricated and customized foot orthoses is also needed.

Neuromuscular adaptations to training, injury and passive interventions: implications for running economy

Performance in endurance sports such as running, cycling and triathlon has long been investigated from a physiological perspective. A strong relationship between running economy and distance running performance is well established in the literature. From this established base, improvements in running economy have traditionally been achieved through endurance training. More recently, research has demonstrated short-term resistance and plyometric training has resulted in enhanced running economy. This improvement in running economy has been hypothesized to be a result of enhanced neuromuscular characteristics such as improved muscle power development and more efficient use of stored elastic energy during running. Changes in indirect measures of neuromuscular control (i.e. stance phase contact times, maximal forward jumps) have been used to support this hypothesis. These results suggest that neuromuscular adaptations in response to training (i.e. neuromuscular learning effects) are an important contributor to enhancements in running economy. However, there is no direct evidence to suggest that these adaptations translate into more efficient muscle recruitment patterns during running. Optimization of training and run performance may be facilitated through direct investigation of muscle recruitment patterns before and after training interventions. There is emerging evidence that demonstrates neuromuscular adaptations during running and cycling vary with training status. Highly trained runners and cyclists display more refined patterns of muscle recruitment than their novice counterparts. In contrast, interference with motor learning and neuromuscular adaptation may occur as a result of ongoing multidiscipline training (e.g. triathlon). In the sport of triathlon, impairments in running economy are frequently observed after cycling. This impairment is related mainly to physiological stress, but an alteration in lower limb muscle coordination during running after cycling has also been observed. Muscle activity during running after cycling has yet to be fully investigated, and to date, the effect of alterations in muscle coordination on running economy is largely unknown. Stretching, which is another mode of training, may induce acute neuromuscular effects but does not appear to alter running economy. There are also factors other than training structure that may influence running economy and neuromuscular adaptations. For example, passive interventions such as shoes and in-shoe orthoses, as well as the presence of musculoskeletal injury, may be considered important modulators of neuromuscular control and run performance. Alterations in muscle activity and running economy have been reported with different shoes and in-shoe orthoses; however, these changes appear to be subject-specific and non-systematic. Musculoskeletal injury has been associated with modifications in lower limb neuromuscular control, which may persist well after an athlete has returned to activity. The influence of changes in neuromuscular control as a result of injury on running economy has yet to be examined thoroughly, and should be considered in future experimental design and training analysis.

A protocol for measuring the direct effect of cycling on neuromuscular control of running in triathletes

The direct effects of cycling on movement and muscle recruitment patterns (neuromuscular control) during running are unknown but critical to success in triathlon. We outline and test a new protocol for investigating the direct influence of cycling on neuromuscular control during running. Leg movement (three-dimensional kinematics) and muscle recruitment (surface electromyography, EMG) were compared between a control run (no prior exercise) and a 30-min transition run that was preceded by 20 min of cycling. We conducted three experiments investigating: (a) the repeatability (between-day reliability) of the protocol; (b) the ability of the protocol to investigate, in highly trained national or international triathletes, the direct influence of cycling on neuromuscular control during running independent of neuromuscular fatigue; and (c) the ability of the protocol to provide a control, or baseline, measure of neuromuscular control (determined using a measure of stability) without causing fatigue. Kinematic and EMG measures of neuromuscular control during running showed moderate to high repeatability: mean coefficients of multiple correlation for repeatability of EMG and kinematics were 0.816 +/- 0.014 and 0.911 +/- 0.031, respectively. The protocol provided a robust baseline measure of neuromuscular control during running without causing neuromuscular fatigue (coefficients of multiple correlation for stability of EMG and kinematics were 0.827 +/- 0.023 and 0.862 +/- 0.054), while EMG and force data provided no evidence of fatigue. The protocol outlined here is repeatable and can be used to measure any direct influence of cycling on neuromuscular control during running.

An open label pilot investigation of the efficacy of Botulinum toxin type A [Dysport] injection in the rehabilitation of chronic anterior knee pain

PURPOSE

To examine the effect of intramuscular injection of botulinum toxin type A [Dysport] to reduce relative overactivity of the vastus lateralis [VL] muscle, in conjunction with re-training of vastus medialis [VM] muscle as an adjunct to rehabilitation for chronic anterior knee pain.

METHOD

Eight females with chronic (>6 months) history of anterior knee pain, who had failed conservative management, were studied in this open label pilot study. Intramuscular Dysport injection [300 - 500 units] to the distal third of VL muscle was followed by a 12-week customized home exercise programme to improve recruitment of VM muscle and functional knee control. VL and VM muscle cross sectional area from a standardized spiral CT sequence, isometric quadriceps strength (dynamometry), timed stair task, self-reported pain and disability were assessed.

RESULTS

Subjects reported reduced knee pain and brace dependency and increased participation in sporting and daily living activities. Isometric quadriceps muscle strength was maintained or improved despite significant atrophy, evident on CT, of the distal component of VL in the treated limb. Time taken to ascend and descend a flight of stairs improved in all subjects. Subjective and objective improvements were maintained at 24-week follow-up.

CONCLUSIONS

These pilot data provide preliminary support for the role of Dysport as an adjunct to non-surgical management of individuals with chronic anterior knee pain. Larger double blind, randomized, placebo-injection controlled studies of this novel approach to improving patellofemoral mechanics are needed to establish the efficacy of this intervention.

Delayed vastus medialis obliquus to vastus lateralis onset timing contributes to the development of patellofemoral pain in previously healthy men: a prospective study

BACKGROUND

Delayed onset of vastus medialis obliquus activity has been described in patellofemoral pain patients. No prospective study investigating the development of patellofemoral pain has tested the onset timing of electromyographic activity of the vastus medialis obliquus and vastus lateralis muscles during a functional task.

HYPOTHESIS

Before the development of patellofemoral pain, subjects demonstrate an altered firing order of the vastus medialis obliquus and vastus lateralis muscles compared with healthy subjects during a functional task.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The onset of vastus medialis obliquus and vastus lateralis activity was measured with surface electromyography during a functional task (rocking back on the heels) in 79 healthy subjects subsequently submitted to a 6-week strenuous basic military training. Afterward, these subjects were reassessed.

RESULTS

Thirty-two percent of the recruits developed patellofemoral pain during training. Patellofemoral pain subjects demonstrated a significant delay of onset of vastus medialis obliquus electromyographic activity compared with the healthy controls (P = .023), even before basic military training. In healthy subjects, no significant differences in electromyographic activity onset of the vastus medialis obliquus compared with the vastus lateralis could be identified before and after basic military training. A significant (P < .001) delay could be demonstrated in the patellofemoral pain group after basic military training. A binary logistic regression could be constructed wherein the onset of the electromyographic activity of the vastus medialis obliquus and vastus lateralis was withheld in the model. The most optimal cutoff value, which is based on the receiver operating characteristic curve, is a timing difference of -0.67 milliseconds (vastus medialis obliquus - vastus lateralis). The area under the receiver operating characteristic curve is considered as fair (0.68).

CONCLUSION

Delayed onset of electromyographic activity of the vastus medialis obliquus-vastus lateralis is one of the contributing risk factors to the development of patellofemoral pain.

Patellar taping affects vastus medialis obliquus activation in subjects with patellofemoral pain before and after quadriceps muscle fatigue

Objective: To investigate the effects of patellar taping on the electromyographic onset of vastus medialis obliquus and vastus lateralis, and their magnitudes of reflex contraction before and after quadriceps muscle fatigue in subjects with patellofemoral pain.

Methods: Sixteen adults (5 males) diagnosed with patellofemoral pain were studied. The timing of surface electromyography onset and magnitude of vastus medialis obliquus and vastus lateralis contractions were measured during a postero-anterior knee perturbation test. The tests were conducted in random order under three conditions of real taping, placebo taping and no taping. Afterwards, the subjects performed knee extension exercises until fatigue and the above tests were repeated, so as to examine the effects of patellar taping in a muscle fatigued condition.

Results: There was no significant difference in electromyographic onset timing of vastus medialis obliquus and vastus lateralis or in the amplitude of vastus lateralis contraction among the different testing conditions. For vastus medialis obliquus amplitude, however, it was significantly higher in the no taping than the real taping condition regardless of the state of fatigue (P = 0.013).

Conclusions: The present study suggests that patellar taping might not enhance the temporal activation of vastus medialis obliquus in subjects with patellofemoral pain before and after muscle fatigue. Furthermore, vastus medialis obliquus contraction might be inhibited by patellar taping.

Does gender influence neuromotor control of the knee and hip?

Patellofemoral pain (PFP) is a common condition that occurs more frequently in females. Anatomical, hormonal and neuromuscular factors have been proposed to contribute to the increased incidence of PFP in females, with neuromuscular factors considered to be of particular importance. This cross-sectional study aimed to evaluate differences in the neuromotor control of the knee and hip muscles between genders and to investigate whether clinical measures of hip rotation range and strength were associated with EMG measures of hip and thigh motor control. Twenty-nine (16 female and 13 male) asymptomatic participants completed a visual choice reaction-time stair stepping task. EMG activity was recorded from vastus medialis oblique, vastus lateralis, anterior and posterior gluteus medius muscles. In addition hip rotation range of motion and hip external rotation, abduction and trunk strength were assessed. There were no differences in the timing or peak of EMG activation of the vasti or gluteus medius muscle between genders during the stepping task. There were however significant associations between EMG measures of motor control of the vasti and hip strength in both females and males. These findings are suggestive of a link between hip muscle control and vasti neuromotor control.

Pain induced by injection of hypertonic saline into the infrapatellar fat pad and effect on coordination of the quadriceps muscles

OBJECTIVE

Musculoskeletal conditions of the knee involve changes in sensorimotor function, but it is unclear whether these changes are a cause or result of pain. Induction of experimental pain may help solve this issue. Although this is commonly achieved by injection of hypertonic saline into muscle, muscle is commonly not the source of pain. This study investigated whether pain induced by injection of saline into the infrapatellar fat pad changes motor control of the quadriceps muscles of the knee.

METHODS

Ten participants performed a standardized task involving ascending and descending a series of steps. Electromyographic activity (EMG) of vastus medialis obliquus (VMO) and vastus lateralis (VL) was recorded with surface electrodes. Trials were conducted without pain, with anterior knee pain induced by injection (0.25 ml) of hypertonic saline (5%) into the infrapatellar fat pad, with anticipation of pain associated with unpredictable electrical shocks to the knee, and 20 minutes after pain cessation. EMG onset and amplitude were analyzed.

RESULTS

When participants ascended the steps with pain, the onset of VMO EMG was delayed relative to that of VL, in contrast to simultaneous or earlier activation of VMO EMG in the pre- and postpain trials. VL EMG amplitude was decreased significantly from the control condition.

CONCLUSION

These data show that alterations in coordination of knee muscle activity can be caused by pain, even when it is of nonmuscle origin. Treatment of pain is therefore important to facilitate performance of the quadriceps muscles, which are essential for locomotor and functional tasks as well as for knee stability.

Início da atividade elétrica dos músculos estabilizadores da patela em indivíduos com SDPF

OBJETIVO: Avaliar a porcentagem de disparo inicial (PDI) dos músculos estabilizadores da patela durante exercícios de contração isométrica voluntária máxima (CIVM) em indivíduos com e sem sinais da síndrome da dor patelofemural (SDPF) nos exercícios de cadeia cinética aberta (CCA) e fechada (CCF). MÉTODO: Foram avaliadas 10 mulheres sem queixa de dor anterior no joelho e 12 mulheres com sinais de SDPF durante a CIM em CCA e CCF com o joelho posicionado a 90º de flexão do joelho. O início da atividade eletromiográfica dos músculos vasto medial obliquo (VMO), vasto lateral obliquo (VLO) e vasto lateral longo (VLL) foi identificada por meio de um algoritmo no programa Myosystem Br 1. A análise estatística empregada foi o teste Qui-Quadrado e o teste t de student, ambos os teste com nível de significância de 5%. RESULTADOS: Os músculos VMO e VLO apresentaram uma maior PDI em relação ao músculo VLL durante os exercícios em CCA para ambos os grupo e para o grupo SDPF em CCF. Não foi observado diferença entre os grupos. CONCLUSÃO: Pode-se sugerir que tanto os exercícios em CCA quanto em CCF, parecem beneficiar o sincronismo na musculatura estabilizadora da patela, podendo ser indicado nos programas de tratamento fisioterapêutico.

Myoelectric manifestations of fatigue in vastus lateralis, medialis obliquus and medialis longus muscles

The purpose of this study was to determine whether surface electromyography (EMG) assessment of myoelectric manifestations of muscle fatigue is capable of detecting differences between the vastus lateralis and medialis muscles which are consistent with the results of previous biopsy studies. Surface EMG signals were recorded from the vastus medialis longus (VML), vastus medialis obliquus (VMO) and vastus lateralis (VL) muscles during isometric knee extension contractions at 60% and 80% of the maximum voluntary contraction (MVC) for 10s and 60s, respectively. Initial values and rate of change of mean frequency (MNF), average rectified value (ARV) and conduction velocity (CV) of the EMG signal were calculated. Comparisons between the two force levels revealed that the initial values of MNF for the VL muscle were greater at 80% MVC compared to 60% MVC (P<0.01). Comparisons between the vasti muscles demonstrated lower initial values of CV for VMO compared to VL at 60% MVC (P<0.01) and lower than VML and VL at 80% MVC (P<0.01). In addition, initial values of MNF were higher for VL with respect to both VML and VMO at 80% MVC (P<0.01) and initial estimates of ARV were higher for VMO compared to VML at both force levels (P<0.01 at 60% MVC and P<0.05 at 80% MVC). For the sustained contraction at 80% MVC, VL demonstrated a greater decrease in CV over time compared to VMO (P<0.05). These findings suggest that surface EMG signals and their time course during sustained isometric contractions may be useful to non-invasively describe functional differences between the vasti muscles.

Management of patients with patellofemoral pain syndrome using a multimodal approach: a case series

STUDY DESIGN

A case series of consecutive patients referred to physical therapy with patellofemoral pain syndrome (PFPS).

BACKGROUND

Physical therapists often treat patients with PFPS, yet there is currently no consensus as to the most effective management strategies. The purpose of this case series is to describe the outcomes of patients referred to physical therapy with PFPS who were treated with a multimodal approach.

CASE DESCRIPTION

Five patients were treated with a combination of thrust and nonthrust manipulation directed at the joints of the lower quarter, trunk and hip stabilization exercises, patellar taping, and foot orthotics. Outcome measures used to capture change in patient status included the Numeric Pain Rating Scale, the Kujala Anterior Knee Pain Scale, the Lower Extremity Functional Scale, and the Global Rating of Change.

OUTCOMES

Five patients (median age, 15 years; range, 14-50 years) with a median duration of knee pain for 8 months (range, 3-24 months) were included in this prospective case series. Four (80%) of the 5 patients demonstrated decreased pain and a clinically significant improvement in function. These gains in function were maintained at a 6-month follow-up.

DISCUSSION

Although a cause-and-effect relationship cannot be inferred from a case series, the outcomes achieved by the patients are consistent with studies incorporating manual physical therapy, exercise, patellar taping, and orthotic prescription to the management of conditions of the lower extremity. Further randomized controlled trials should be performed to determine the effectiveness of this multimodal approach for the management of individuals with PFPS.

Targeted physiotherapy for patellofemoral joint osteoarthritis: a protocol for a randomised, single-blind controlled trial

Background

The patellofemoral joint (PFJ) is one compartment of the knee that is frequently affected by osteoarthritis (OA) and is a potent source of OA symptoms. However, there is a dearth of evidence for compartment-specific treatments for PFJ OA. Therefore, this project aims to evaluate whether a physiotherapy treatment, targeted to the PFJ, results in greater improvements in pain and physical function than a physiotherapy education intervention in people with symptomatic and radiographic PFJ OA.

Methods

90 people with PFJ OA (PFJ-specific history, signs and symptoms and radiographic evidence of PFJ OA) will be recruited from the community and randomly allocated into one of two treatments. A randomised controlled trial adhering to CONSORT guidelines will evaluate the efficacy of physiotherapy (8 individual sessions over 12 weeks, as well as a home exercise program 4 times/week) compared to a physiotherapist-delivered OA education control treatment (8 individual sessions over 12 weeks). Physiotherapy treatment will consist of (i) quadriceps muscle retraining; (ii) quadriceps and hip muscle strengthening; (iii) patellar taping; (iv) manual PFJ and soft tissue mobilisation; and (v) OA education. Resistance and dosage of exercises will be tailored to the participant's functional level and clinical state. Primary outcomes will be evaluated by a blinded examiner at baseline, 12 weeks and 9 months using validated and reliable pain, physical function and perceived global effect scales. All analyses will be conducted on an intention-to-treat basis using linear mixed regression models, including respective baseline scores as a covariate, subjects as a random effect, treatment condition as a fixed factor and the covariate by treatment interaction.

Conclusion

This RCT is targeting PFJ OA, an important sub-group of knee OA patients, with a specifically designed conservative intervention. The project's outcome will influence PFJ OA rehabilitation, with the potential to reduce the personal and societal burden of this increasing public health problem.

Trial Registration

Australia New Zealand Clinical Trials Registry ACTRN12608000288325

Vastus medialis cross-sectional area is associated with patella cartilage defects and bone volume in healthy women

OBJECTIVES

Although vastus medialis and vastus lateralis are important muscular determinants of patellofemoral joint function, it is unclear how these muscles relate to the structure of the patellofemoral joint. The aim of this cross-sectional study was to determine the relationship between the vasti muscles and patella cartilage volume and defects and patella bone volume.

METHODS

One hundred and seventy-five women, aged 40-67 years, with no knee pain or clinical lower-limb disease had magnetic resonance imaging (MRI) of their dominant knee. The cross-sectional areas of the distal vastus medialis and lateralis were measured 37.5mm superior to the quadriceps tendon insertion at the proximal pole of the patella. Patella cartilage volume and defects and patella bone volume were measured from these images using validated methods.

RESULTS

There was no significant association between the distal vastus medialis cross-sectional area and patella cartilage volume. For every 1mm(2) increase in the distal vastus medialis cross-sectional area, there was an associated increased risk of patella cartilage defects [odds ratio (OR): 1.2; 95% confidence interval (CI) 1.004, 1.5; P=0.05], and an associated increase in patella bone volume (OR: 3.9; 95% CI 2.0, 5.8; P<0.001) after adjustment for potential confounders. There was no significant relationship between vastus lateralis cross-sectional area and measures of patella cartilage or bone.

CONCLUSION

An increased cross-sectional area of the distal portion of the vastus medialis muscle is associated with an increased risk of patella cartilage defects, and an increase in patella bone volume among healthy women. Although these results need to be confirmed in longitudinal studies, they suggest that an increase in the distal vastus medialis cross-sectional area is associated with structural change at the patellofemoral joint.

Patellofemoral pain syndrome (PFPS): a systematic review of anatomy and potential risk factors

Background

Patellofemoral Pain Syndrome (PFPS), a common cause of anterior knee pain, is successfully treated in over 2/3 of patients through rehabilitation protocols designed to reduce pain and return function to the individual. Applying preventive medicine strategies, the majority of cases of PFPS may be avoided if a pre-diagnosis can be made by clinician or certified athletic trainer testing the current researched potential risk factors during a Preparticipation Screening Evaluation (PPSE). We provide a detailed and comprehensive review of the soft tissue, arterial system, and innervation to the patellofemoral joint in order to supply the clinician with the knowledge required to assess the anatomy and make recommendations to patients identified as potentially at risk. The purpose of this article is to review knee anatomy and the literature regarding potential risk factors associated with patellofemoral pain syndrome and prehabilitation strategies. A comprehensive review of knee anatomy will present the relationships of arterial collateralization, innervations, and soft tissue alignment to the possible multifactoral mechanism involved in PFPS, while attempting to advocate future use of different treatments aimed at non-soft tissue causes of PFPS.

Methods

A systematic database search of English language PubMed, SportDiscus, Ovid MEDLINE, Web of Science, LexisNexis, and EBM reviews, plus hand searching the reference lists of these retrieved articles was performed to determine possible risk factors for patellofemoral pain syndrome.

Results

Positive potential risk factors identified included: weakness in functional testing; gastrocnemius, hamstring, quadriceps or iliotibial band tightness; generalized ligamentous laxity; deficient hamstring or quadriceps strength; hip musculature weakness; an excessive quadriceps (Q) angle; patellar compression or tilting; and an abnormal VMO/VL reflex timing. An evidence-based medicine model was utilized to report evaluation criteria to determine the at-risk individuals, then a defined prehabilitation program was proposed that begins with a dynamic warm-up followed by stretches, power and multi-joint exercises, and culminates with isolation exercises. The prehabilitation program is performed at lower intensity level ranges and can be conducted 3 days per week in conjunction with general strength training. Based on an objective one repetition maximum (1RM) test which determines the amount an individual can lift in good form through a full range of motion, prehabilitation exercises are performed at 50–60% intensity.

Conclusion

To reduce the likelihood of developing PFPS, any individual, especially those with positive potential risk factors, can perform the proposed prehabilitation program.

Frontal plane leg alignment and muscular activity during maximum eccentric contractions in individuals with and without patellofemoral pain syndrome

PURPOSE

The role of frontal plane tibiofemoral alignment in subjects with patellofemoral pain syndrome (PFPS) is controversial and rarely discussed in the literature. As well, little research has been done on the effects of the hamstrings muscles on PFPS. The aim of the current study was to determine whether, in individuals with PFPS, frontal plane tibiofemoral alignment or muscular activity of the index knee's crossing muscles is altered during maximum eccentric leg press exercise.

METHODS

This cross-sectional study involved 19 patients with PFPS and 19 control subjects who were matched according to gender, age, and physical activity. During eccentric leg press action, frontal plane tibiofemoral alignment was assessed with a motion analysis system based on skin markers. Simultaneously, surface-electromyography was used to assess the activity levels of the relevant knee crossing muscles. To assess the activity under functional conditions, a leg press with a footplate having variable stability was used for barefoot testing.

RESULTS

The PFPS subjects did not have significantly different frontal plane leg alignment compared to controls. On electromyography (EMG), PFPS patients had significantly lower levels of hamstring activity during eccentric leg exercise. The differences between the two groups (%; absolute differences normalized EMG) ranged from 20% (semitendinosus; stable footplate; p=0.017) to 21% (biceps femoris; unstable footplate; p=0.019) and 32% (semitendinosus; unstable footplate; p=0.002).

CONCLUSIONS

PFPS is not linked to altered frontal plane leg alignment during eccentric leg pressing. However, PFPS is associated with eccentric under-activation of the hamstrings, which may be a compensatory strategy that maintains patellofemoral joint pressure within bearable levels.

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

Background

Anterior knee pain (AKP) is a common musculoskeletal complaint. It has been suggested that one factor that may contribute to the presence of AKP is a delay in the recruitment of the vastus medialis oblique muscle (VMO) relative to the vastus lateralis muscle (VL). There is however little consensus within the literature regarding the existence or nature of any such delay in the recruitment of the VMO within the AKP population. The purpose of this systematic review and meta-analysis was to examine the relative timing of onset of the VMO and VL in those with AKP in comparison to the asymptomatic population.

Methods

The bibliographic databases AMED, British Nursing Index, CINAHL, EMBASE, Ovid Medline, PEDro, Pubmed and the Cochrane Library were searched for studies comparing the timing of EMG onset of the VMO and VL in those with AKP versus the asymptomatic population. Studies fulfilling the inclusion criteria were independently assessed. Heterogeneity across the studies was measured. A meta-analysis of results was completed for those studies where adequate data was supplied. Where comparable methodologies had been used, results were pooled and analysed.

Results

Fourteen studies met the inclusion criteria; one prospective and thirteen observational case control. Eleven compared VMO and VL EMG onset times during voluntary active tasks while four investigated reflex response times. All used convenience sampling and did not state blinding of the assessor. Study methodologies/testing and assessment procedures varied and there was considerable heterogeneity within individual samples. Whilst a trend was identified towards a delay in onset of VMO relative to the VL in the AKP population during both voluntary active tasks and reflex activity, a substantial degree of heterogeneity across the pooled studies was identified (I² = 69.9–93.4%, p < 0.01).

Conclusion

Findings are subject to substantial and unexplained heterogeneity. A trend was demonstrated towards a delayed onset of VMO relative to VL in those with AKP in comparison to those without. However not all AKP patients demonstrate a VMO-VL dysfunction, and this is compounded by normal physiological variability in the healthy population. The clinical and therapeutic significance is therefore difficult to assess.

Disability in patients with chronic patellofemoral pain syndrome: a randomised controlled trial of VMO selective training versus general quadriceps strengthening

This study was a prospective single blind randomised controlled trial to compare the effects of rehabilitation with emphasis on retraining the vastus medialis (VMO) component of the quadriceps femoris muscle and rehabilitation with emphasis on general strengthening of the quadriceps femoris muscles on pain, function and Quality of Life in patients with patellofemoral pain syndrome (PFPS). Patients with PFPS (n=69) were recruited from a hospital orthopaedic clinic and randomised into three groups: (1) physiotherapy with emphasis on selectively retraining the VMO (Selective); (2) physiotherapy with emphasis on general strengthening of the quadriceps femoris muscles (General); and (3) a no-treatment control group (Control). The three groups were then compared before and after an eight-week rehabilitation period. The Selective and General groups demonstrated statistically significant and 'moderate' to 'large' effect size reductions in pain when compared to the Control group. Both the Selective and General groups displayed statistically significant and 'moderate' and 'large' effect size improvements in subjective function and Quality of Life compared to the Control group. Knee flexion excursion during the stance phase of gait, demonstrated that there were no statistical significant differences and only 'trivial' to 'small' effect size differences between the Selective or General groups and the Control group. A large number of PFPS patients can experience significant improvements in pain, function and Quality of Life, at least in the short term, with quadriceps femoris rehabilitation, with or without emphasis on selective activation of the VMO component. Both approaches would seem acceptable for rehabilitating patients with PFPS. It may be appropriate to undertake exercises involving selective activation of the vastus medialis early in the rehabilitation process, however, clinicians should not overly focus on selective activation before progressing rehabilitation, especially in more chronic cases with significant participation restrictions.

Quadriceps activity and movement reactions in response to unpredictable sagittal support-surface translations in women with patellofemoral pain

Patellofemoral pain (PFP) may be related to unfavorable knee joint loading. Delayed and/or reduced activity of vastus medialis obliquus (VMO) and different movement patterns have been identified in individuals with PFP in some studies, whereas other studies have failed to show a difference compared to non-affected controls. The discrepancy between study results may depend on the different tasks that have been investigated. No previous study has investigated these variables in postural responses to unpredictable perturbations in PFP. Whole body three dimensional kinematics and surface EMG of quadriceps muscles activation was studied in postural responses to unpredictable support surface translations in 17 women with PFP who were pain free at the time of testing, and 17 matched healthy controls. The results of the present study showed earlier onset of VMO activity and associated changes in kinematics to anterior platform translation in the PFP subjects. We suggest that the relative timing between the portions quadriceps muscles may be task specific and part of an adapted response in attempt to reduce knee joint loading. This learned response appears to remain even when the pain is no longer present.

Biofeedback exercise improved the EMG activity ratio of the medial and lateral vasti muscles in subjects with patellofemoral pain syndrome

Patellofemoral pain syndrome (PFPS) is usually due to weakness of vastus medialis obliquus (VMO) resulting in abnormal patellar tracking. One of the objectives of rehabilitation is to strengthen the VMO so as to counterbalance the vastus lateralis (VL) action during normal activities. This study compared the effects of an 8-week exercise program with and without EMG biofeedback on the relative activations of VMO and VL. Twenty-six subjects with PFPS were randomly allocated into an "exercise" group (Group 1) and a "biofeedback+exercise" group (Group 2). Both groups performed the same exercise program but subjects in Group 2 received real time EMG biofeedback information on the relative activations of VMO and VL during the exercises. After 8 weeks of training, Group 1 had insignificant changes in their VMO/VL EMG ratio (p=0.355), whereas Group 2 had significantly greater VMO/VL EMG ratio (p=0.017) when performing normal activities throughout a 6-h assessment period. The present result reveals that the incorporation of an EMG biofeedback into a physiotherapy exercise program could facilitate the activation of VMO muscle such that the muscle could be preferentially recruited during daily activities.

Fisioterapia em pacientes com síndrome fêmoro-patelar: comparação de exercícios em cadeia cinética aberta e fechada

Este estudo teve como objetivo comparar a eficácia do fortalecimento muscular na recuperação funcional da síndrome fêmoro-patelar (SFP). Foram selecionadas 20 mulheres com SFP divididas em dois grupos: o Grupo 1 (G1) realizou fortalecimento do músculo quadríceps femoral em cadeia cinética aberta (CCA) e o Grupo 2 (G2) em cadeia cinética fechada (CCF), durante oito semanas com freqüência de duas vezes semanais. Foi avaliada a dor, capacidade funcional, flexibilidade, encurtamento dos músculos isquiotibiais, ângulo Q e eletromiografia (EMG) dos músculos vasto medial (VM) e vasto lateral (VL) durante extensão isométrica da perna. Antes e após o tratamento, as variáveis foram analisadas pelo teste de Wilcoxon, e entre os grupos pelo teste t para amostras independentes ou Anova de Friedman ou Manova (a<0,05). Após o tratamento, os resultados mostram que houve melhora da capacidade funcional, encurtamento dos músculos isquiotibiais e flexibilidade. Porém, somente o G1 apresentou diminuição da intensidade da dor e aumento da atividade EMG do músculo VL, enquanto ambos não modificaram o ângulo Q. Os dados sugerem que os tratamentos baseados no fortalecimento do músculo quadríceps femoral possibilitaram melhoras importantes nos principais sinais e sintomas apresentados pelas pacientes, não havendo diferenças evidentes entre os realizados em CCA e CCF.

The influence of body position on leg kinematics and muscle recruitment during cycling

The effects of upper body orientation on neuromuscular control of the leg during cycling are not well understood. Our aim was to investigate the effects of upper body orientation on control of movement of distal leg segments during cycling. We compared three-dimensional leg and foot kinematics and muscle recruitment patterns between upright and aerodynamic riding positions. Comparisons were made between 10 elite cyclists, 10 elite triathletes and 10 novice cyclists. We found that upper body orientation did not influence kinematics of the leg and foot or primary muscle activity (i.e., the main bursts of muscle activity). The aerodynamic riding position was, however, associated with less modulation of muscle activity (i.e., less relaxation of the muscle during secondary muscle activity) and greater coactivity in elite triathletes and novice cyclists. Our results suggest that orientation of the upper body influences neuromuscular control of the leg during cycling in elite triathletes and novice cyclists. The change in muscle recruitment (i.e., the change in how the goal movement was achieved) implies that the ability of the central nervous system to execute the cycling movement in the most skilled manner was adversely influenced by upper body orientation in elite triathletes and novice cyclists. Less modulation of muscle activity and greater coactivation in elite triathletes when cycling in the aerodynamic position, and the similarity of changes shown in elite triathletes and novice cyclists, may be interpreted as further evidence of less skilled control of movement in elite triathletes when compared to cyclists matched for cycling training history.

Patellofemoral Pain

Patellofemoral pain is an extremely common disorder, especially in female athletes. There is, however, no true consensus as to the cause and appropriate treatment for patellofemoral pain. This article reviews the epidemiology of patellofemoral pain as well as the proposed etiologies, including quadriceps dysfunction, static alignment disorders, and dynamic alignment disorders. The article also reviews both conservative and surgical treatment of patellofemoral pain.

Leg muscle recruitment during cycling is less developed in triathletes than cyclists despite matched cycling training loads

Studies of arm movements suggest that interference with motor learning occurs when multiple tasks are practiced in sequence or with short interim periods. However, interference with learning has only been studied during training periods of 1-7 days and it is not known if interference with learning continues during long-term multitask training. This study investigated muscle recruitment in highly trained triathletes, who swim, cycle and run sequentially during training and competition. Comparisons were made to highly trained and novice cyclists, i.e. between trained multidiscipline, trained single-discipline and novice single-discipline athletes, to investigate adaptations of muscle recruitment that occur in response to ongoing multitask, or multidiscipline, training. Electromyographic (EMG) activity of five leg muscles, tibialis anterior, tibialis posterior, peroneus longus, gastrocnemius lateralis and soleus muscles, was recorded during cycling using intramuscular fine-wire electrodes. Differences were found between trained triathletes and trained cyclists in recruitment of all muscles, and patterns of muscle recruitment in trained triathletes were similar to those recorded in novice cyclists. More specifically, triathletes and novice cyclists were characterised by greater sample variance (i.e. greater variation between athletes), greater variation in muscle recruitment patterns between pedal strokes for individual cyclists, more extensive and more variable muscle coactivation, and less modulation of muscle activity (i.e. greater EMG amplitude between primary EMG bursts). In addition, modulation of muscle activity decreased with increasing cadence (i.e. the amplitude and duration of muscle activity was greater at higher movement speeds) in both triathletes and novice cyclists but modulation of muscle activity was not influenced by cadence in trained cyclists. Our findings imply that control of muscle recruitment is less developed in triathletes than in cyclists matched for cycling training loads, which suggests that multidiscipline training may interfere with adaptation of the neuromuscular system to cycling training in triathletes.

Rehabilitation and Nonoperative Treatment of Patellar Instability

Patellofemoral instability can be a difficult condition for clinicians to manage. Differentiation needs to be made as to whether the problem is an acute injury where a traumatic incident has usually precipitated the dislocation or whether the problem is a recurrent instability where the patellofemoral joint is unstable during everyday activities. This review defines instability, discusses the factors affecting instability, and provides assessment procedures and nonoperative intervention strategies for the clinician.