A biomechanical and clinical evaluation of a patellofemoral knee brace

Immediate effects of an elastic patellar brace on pain, neuromuscular activity and knee kinematics in subjects with patellofemoral pain

INTRODUCTION

The aim of this randomized controlled trial was to investigate immediate effects of a patellar brace on pain, neuromuscular activity, and knee kinematics in subjects with patellofemoral pain syndrome.

MATERIALS AND METHODS

Fifty subjects with a diagnosis of patellofemoral pain syndrome completed 6 activities each with and without a patellar brace in a randomized order. The subjects were asked to rate their perceived pain on a Visual Analog Scale after each activity. During the activities, neuromuscular activity of vastus medialis and vastus lateralis, as well as knee angles were measured.

RESULTS

Subjects showed a statistically significant pain reduction of 33-56% on the Visual Analog Scale during all activities while wearing the brace. Two groups with different onset patterns for vastus medialis and vastus lateralis were identified: one group who activated vastus medialis prior to vastus lateralis, and one who activated vastus medialis after vastus lateralis. In the subgroup of subjects activating vastus lateralis prior to vastus medialis, bracing resulted in a significantly (p = 0.048) earlier onset of vastus medialis by 56 ms. In all but one activity, the vastus medialis/vastus lateralis ratio without the patellar brace was < 1.0 and inverted with the patellar brace > 1.0. Knee angles in the sagittal plane increased significantly with the patellar brace in two activities.

CONCLUSION

Patellofemoral bracing results in an immediate decrease of pain, an earlier onset of vastus medialis and inverted vastus medialis/vastus lateralis ratio and altered knee kinematics.

Prevalence of knee injuries among male college students in Riyadh, Kingdom of Saudi Arabia

BACKGROUND

The knee is considered the most common injured joint between young sport participants. However, there is lack of proper prevalence estimation in our population. The purpose of this study was to identify the prevalence of knee injuries among male college students and to observe the demographic data associated with it. Our secondary objective was to evaluate the awareness and knowledge about these injuries.

METHODS

This is a cross-sectional study. A survey was distributed to collect the data among male college students, King Saud University, Riyadh, Saudi Arabia. Out of 688 students who participated and completed the questionnaire, a total of 482 were considered valid and met the inclusion criteria. Data were analyzed using Statistical Package for Social Sciences (SPSS).

RESULTS

The overall prevalence of knee injury was 23.2% (n = 112). Most of them injured during sport activities especially soccer and 68.7% involved in a non-contact mechanism of injury. Among those who went to a hospital mostly were diagnosed as contusion (31.4%) then as meniscus tear, ACL, and collateral ligament injury, respectively. Majority was treated conservatively and only 10.7% needed surgery surprisingly. There was no statistically significant difference between those who are injured and whether they were warmed up and stretched or not (P = 0.619). Low level of knowledge about knee injuries was noticed among the participants 57.7%.

CONCLUSION

Our study has highlighted the high prevalence of knee injuries and the need to raise the level of awareness and knowledge about these injuries in our population. Soccer was the most common sport associated with knee injuries; most of these injuries were treated conservatively.

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 effect of patellofemoral bracing on walking in individuals with patellofemoral pain syndrome

BACKGROUND

Although knee braces are used by individuals with patellofemoral pain syndrome, the effect of patellofemoral bracing on knee flexion during walking has not been elucidated.

AIM

The purpose of this study was to evaluate the effect of patellofemoral bracing on sagittal plane knee joint kinematics and temporal spatial parameters during walking in individuals with patellofemoral pain syndrome.

STUDY DESIGN

Quasi-experimental.

METHODS

Ten subjects with a diagnosis of patellofemoral pain syndrome were fitted with a knee brace incorporating an infrapatellar strap. Testing was performed at baseline and after 6 weeks of use. Gait analysis and a visual analog scale were used to assess outcomes in this study.

RESULTS

A 59.6% decrease in pain was reported by using bracing. Bracing significantly improved speed of walking (p ≤ 0.001) and step length (p ≤ 0.001). The mean cadence was also increased following 6 weeks of patellofemoral brace use, but this was not significant (p = 0.077). Knee flexion angles improved during initial contact, loading response, and mid-swing (p ≤ 0.001) after 6 weeks of patellofemoral brace use.

CONCLUSION

Knee orthoses resulted in decreased pain, improved temporal spatial parameters (speed of walking and step length), and increased knee flexion angles during ambulation in patients with patellofemoral pain syndrome.

The effect of patellar taping on squat depth and the perception of pain in people with anterior knee pain

Patellar taping is a treatment adjunct commonly used in the management of anterior knee pain. The aim of this cross sectional study was to investigate the effects of medial glide patellar taping on sagittal plane lower-limb joint kinematics and knee pain during a unilateral squat in a symptomatic population complaining of anterior knee pain. Ten participants with a history of unilateral or bilateral anterior knee pain were included in the study. Subjects were required to squat on the symptomatic leg under three conditions: placebo tape, patellar tape and no tape. Kinematic data was recorded using the CODA mpx64 motion analysis system and subjects' pain was assessed using the Numerical Rating Scale. Patellar taping resulted in a significantly greater single-legged squat depth compared to placebo tape (p=0.008) and no tape (p=0.001) and a statistically significant reduction in pain during a squat compared to placebo tape (p=0.001) or no tape (p=0.001). Significant differences were not identified for maximum knee flexion in the patella taping compared to the no tape condition. This study may have significant clinical implications as participants reported less pain and alterations in sagittal plane movement following the application of patellar tape.

A clinical study of the biomechanics of step descent using different treatment modalities for patellofemoral pain

INTRODUCTION

In the previous study we have demonstrated that in healthy subjects significant changes in coronal and transverse plane mechanics can be produced by the application of a neutral patella taping technique and a patellar brace. Recently it has also been identified that patients with patellofemoral pain syndrome (PFPS) display alterations in gait in the coronal and transverse planes.

OBJECTIVE

This study investigated the effect of patellar bracing and taping on the three-dimensional mechanics of the knee of patellofemoral pain patients during a step descent task.

METHOD

Thirteen patients diagnosed with patellofemoral pain syndrome performed a slow step descent. This was conducted under three randomized conditions: (a) no intervention, (b) neutral patella taping, (c) patellofemoral bracing. A 20cm step was constructed to accommodate an AMTI force platform. Kinematic data were collected using a ten camera infra-red Oqus motion analysis system. Reflective markers were placed on the foot, shank and thigh using the Calibrated Anatomical System Technique (CAST).

RESULTS

The coronal plane knee range of motion was significantly reduced with taping (P=0.031) and bracing (P=0.005). The transverse plane showed a significant reduction in the knee range of motion with the brace compared to taping (P=0.032) and no treatment (P=0.046).

CONCLUSION

Patients suffering from patellofemoral pain syndrome demonstrated improved coronal plane and torsional control of the knee during slow step descent following the application of bracing and taping. This study further reinforces the view that coronal and transverse plane mechanics should not be overlooked when studying patellofemoral pain.

Using real-time MRI to quantify altered joint kinematics in subjects with patellofemoral pain and to evaluate the effects of a patellar brace or sleeve on joint motion

Abnormal patellofemoral joint motion is a possible cause of patellofemoral pain, and patellar braces are thought to alleviate pain by restoring normal joint kinematics. We evaluated whether females with patellofemoral pain exhibit abnormal patellofemoral joint kinematics during dynamic, weight-bearing knee extension and assessed the effects of knee braces on patellofemoral motion. Real-time magnetic resonance (MR) images of the patellofemoral joints of 36 female volunteers (13 pain-free controls, 23 patellofemoral pain) were acquired during weight-bearing knee extension. Pain subjects were also imaged while wearing a patellar-stabilizing brace and a patellar sleeve. We measured axial-plane kinematics from the images. Females with patellofemoral pain exhibited increased lateral translation of the patella for knee flexion angles between 0 degrees and 50 degrees (p = 0.03), and increased lateral tilt for knee flexion angles between 0 degrees and 20 degrees (p = 0.04). The brace and sleeve reduced the lateral translation of the patella; however, the brace reduced lateral displacement more than the sleeve (p = 0.006). The brace reduced patellar tilt near full extension (p = 0.001), while the sleeve had no effect on patellar tilt. Our results indicate that some subjects with patellofemoral pain exhibit abnormal weight-bearing joint kinematics and that braces may be effective in reducing patellar maltracking in these subjects.

Kinematic analyses during stair descent in young women with patellofemoral pain

BACKGROUND

Compensatory movement strategies may develop in response to pain to avoid stress on the affected area. Patellofemoral pain is characterised by intermittent periods of pain and the present study addresses whether long-term pain leads to compensatory movement strategies that remain even when the pain is absent.

METHOD

Lower extremity kinematics in three dimensions was studied in stair descent in 17 women with patellofemoral and in 17 matched controls. A two-dimensional geometric model was constructed to normalise kinematic data for subjects with varying anthropometrics when negotiating stairs of fixed proportions.

RESULTS

There were minor differences in movement patterns between groups. Knee joint angular velocity in the stance leg at foot contact was lower and the movement trajectory tended to be jerkier in the patellofemoral group. The two-dimensional model showed greater plantar flexion in the swing leg in preparation for foot placement in the patellofemoral group.

INTERPRETATION

The results indicate that an altered stair descent strategy in the patellofemoral group may remain also in the absence of pain. The biomechanical interpretation presumes that the strategy is aimed to reduce knee joint loading by less knee joint moment and lower impact force.

The biomechanics of step descent under different treatment modalities used in patellofemoral pain

BACKGROUND

Most previous work on the use of knee bracing and taping has focussed on sagittal plane movement. However, most bracing and taping techniques aim to modify patellar movement in the coronal and transverse planes.

OBJECTIVE

This study investigated the effect of patellar bracing and taping on the three-dimensional mechanics of the knee during a controlled eccentric step down task.

METHOD

Twelve healthy subjects were asked to conduct a slow step down exercise. The step down was conducted under three randomised conditions: (a) no intervention, (b) neutral patella taping and (c) patellofemoral bracing. A step was constructed to accommodate an AMTI force platform and to produce a step height of 20 cm. Kinematic data were collected using a six camera ProReflex motion analysis system. Reflective markers were placed on the foot, shank and thigh using the Calibrated Anatomical Systems Technique (CAST).

RESULTS

The patellofemoral brace and taping led to a significant reduction in the maximum coronal and range of torsional knee angles by 5 degrees and 2 degrees , respectively (p=0.030, 0.006). The range of coronal and transverse plane knee moments was also significantly reduced by 0.15 Nm/kg and 0.03 Nm/kg (p=0.020, 0.0019). The brace was shown to be more effective in the coronal and transverse planes in comparison to taping or no intervention.

CONCLUSION

Bracing and taping appear to offer coronal plane and torsional control of the knee during eccentric step descent. Coronal and transverse plane mechanics should not be overlooked when studying patellofemoral pain.

Surgical biomechanics of the patellofemoral joint

This review presents objective data, as far as possible, about the current understanding of the biomechanics of the patellofemoral joint as it pertains to the management of patellofemoral problems. When faced with a patellofemoral malfunction, it is important to check all the soft-tissue and articular geometry factors relating to the patella locally and not to neglect the overall lower limb alignment and function. It is important to remember that small alterations in alignment can result in significant alterations in patellofemoral joint stresses and that changes in the mechanics of the patellofemoral joint can also result in changes in the tibiofemoral compartments. Surgical intervention for patellofemoral problems needs to be planned carefully and take into account an individual's anatomy.

Effect of patellar taping on vasti onset timing, knee kinematics, and kinetics in asymptomatic individuals with a delayed onset of vastus medialis oblique

This randomized within-subject study investigated the effects of patellar tape on the onset of electromyographic (EMG) activity of vastus medialis obliquus (VMO) relative to vastus lateralis (VL), knee kinematics, and kinetics in 12 currently asymptomatic individuals with a VMO timing deficit and a history of patellofemoral pain. Participants were required to complete stair stepping and normal-pace and fast-pace walking tasks under three experimental conditions; no tape, control tape and therapeutic tape. EMG onsets of VMO and VL were measured by surface electrodes, stance phase knee flexion by the PEAK movement analysis system and vertical ground reaction force by a force plate. A two-way repeated measures analysis of variance showed that neither therapeutic tape nor control tape had any effect on the EMG VMO-VL onset timing difference. Therapeutic tape, but not control tape, led to significant increases in stance phase knee flexion. The first peak vertical ground reaction force was lowered by both control and therapeutic tape but only during fast walking. The results suggest that tape induced effects on neuromotor control of the vasti seen in other studies are related to reductions in pain rather than the presence of a baseline timing deficit. However, this cannot explain the improvements in stance phase knee flexion observed with tape.

Physical Therapy Improves Knee Flexion during Stair Ambulation in Patellofemoral Pain

PURPOSE

This study aimed to examine whether a physical therapy intervention, designed to reduce pain and improve the neuromotor control resulted in greater improvements in stance-phase knee flexion during stair ambulation in individuals with patellofemoral pain. The relationship between changes in stance-phase knee flexion and changes in pain, disability, and onset timing of individual vasti activity was also examined.

METHODS

Forty participants aged 40 yr or younger diagnosed with patellofemoral pain were randomly allocated to a physical therapy (N = 21) or placebo (N = 19) treatment group. Stance-phase knee flexion was measured in two dimensions using a PEAK movement analysis system during stair ambulation. Individuals were divided into those with improvements in onset of vastus medialis obliquus (VMO) activity relative to that of the vastus lateralis (VL) of more or less than 10 ms.

RESULTS

Groups were similar at baseline. After the 6-wk intervention, individuals in the physical therapy group had significantly greater changes in knee flexion at heel strike (mean difference 4 degrees, 95% CI = 2-7 degrees) and peak stance-phase knee flexion (mean difference 9 degrees, 95% CI = 5-12 degrees) than those in the placebo group. No differences were noted during stair ascent. Individuals with greater change in the onset timing of the vasti had greater improvements in stance-phase knee flexion. Changes in usual pain in the week before testing and change in the vasti onset timing were independent predictors of change in stance-phase knee flexion during stair descent, together accounting for 27-40% of the variability in knee motion.

CONCLUSIONS

Physical therapy intervention resulted in significantly greater changes in knee joint motion than a placebo treatment, and these changes in knee motion were partly related to changes in pain and changes in onset timing of the vasti.

The Effect of Bracing on Patella Alignment and Patellofemoral Joint Contact Area

PURPOSE

To examine the influence of two patellofemoral braces on pain response, patellar alignment, and patellofemoral joint contact area in persons with patellofemoral pain.

METHODS

Fifteen women between the ages of 18 and 45 yr with a diagnosis of patellofemoral pain participated. After the assessment of pain response using a visual analog scale, subjects underwent axial plane magnetic resonance imaging of patellofemoral joint at 0 degrees, 20 degrees, 40 degrees, and 60 degrees of knee flexion. Imaging was done with the knee extensors contracted (25% body weight) under three conditions: 1) no brace, 2) On-Track brace, and 3) Patellar Tracking Orthosis (PTO). Measures of mediolateral patellar displacement and tilt and medial and lateral facet contact area were obtained from the magnetic resonance images.

RESULTS

On average, the On-Track brace reduced symptoms by 50%, whereas the PTO reduced pain by 44%. When averaged across all knee flexion angles, the PTO and the On-Track brace significantly increased total patellofemoral joint contact area by 52.0 mm (21%) and 59.3 mm (24%), respectively, when compared with the no-brace condition. Bracing had no influence on lateral patellar tilt; however, small but significant changes in lateral patellar displacement were observed.

CONCLUSION

Large changes in pain and contact area occurred without sizable changes in patellar alignment. The results of this study suggest that changes in patellar alignment by itself may not be responsible for pain alleviation after patellar bracing.

Effect of bracing on patellofemoral joint stress while ascending and descending stairs

OBJECTIVE

To test the hypothesis that individuals who respond favorably to bracing will exhibit decreased patellofemoral joint stress during stair ambulation.

DESIGN

A repeated-measures, cross-sectional study.

BACKGROUND

Ascending and descending stairs is one of the most painful activities of daily living for persons with patellofemoral pain (PFP). Although patellar bracing has been shown to reduce symptoms during such tasks, the underlying mechanism has not been identified.

METHODS

Fifteen subjects with a diagnosis of PFP completed 2 phases of data collection: (1) magnetic resonance imaging to determine patellofemoral joint contact area, and (2) gait analysis during stair ascent and descent. Data were obtained under braced and non-braced conditions. Variables obtained from both data collection sessions were used as input variables into a biomechanical model to quantify patellofemoral joint stress.

RESULTS

Although subjects reported an average decrease in pain of 56%, bracing did not reduce peak stress during stair ascent and descent. This finding can be explained by the fact that despite improvements in contact area, bracing resulted in greater knee extensor muscle moments and joint reaction forces.

CONCLUSIONS

Our results do not support the hypothesis that individuals with PFP would demonstrate reduced patellofemoral stress during stair ambulation following the application of a patellar brace.

CLINICAL RELEVANCE

Although bracing did not decrease patellofemoral joint stress during stair ascent and descent, the decrease in pain, increase in quadriceps utilization, and tolerance of joint reaction forces would appear to be beneficial consequences of bracing.

Ergonomic Pain--Part 2: Differential Diagnosis and Management Considerations

Work-related musculoskeletal disorders (MSDs) can produce ergonomic pain in several different regions of the body, including the shoulder, elbow, wrist and hand, lumbar spine, knee, and ankle/foot. Each family of disorders is distinctive in presentation and requires diagnosis-specific interventions. Because of the complex nature of these disorders, management approaches may not always eliminate symptoms and or completely restore patient function to a level found prior to symptom onset. As a consequence, ergonomic measures should be implemented to reduce the overload on tissue and contribute to patient recovery. However, functional limits may persist and the clinician must make further decisions regarding a person's functional status in the chronic stages of the patient's care.

Knee flexion during stair ambulation is altered in individuals with patellofemoral pain

Reduced knee flexion is a logical gait adaptation for individuals with patellofemoral pain (PFP) to lessen the patellofemoral joint reaction force and minimise pain during stair ambulation. This gait adaptation may be related to the co-ordination of individual vasti components.

PURPOSE

This study investigated the amount of stance-phase knee flexion in individuals with (n=48) and without (n=18) PFP using a cross-sectional design. The relationship between stance-phase knee flexion and onset timing of individual vasti activity was also examined.

METHOD

Stance-phase knee flexion was measured in 2-dimensions using a PEAK movement analysis system during stair ascent and descent. Individuals with PFP were separated into those with synchronous onset of the EMG activity of vastus medialis obliquus (VMO) and vastus lateralis (VL), and those where the onset of VMO EMG activity was delayed relative to the VL.

RESULTS

The amount of knee flexion at heel-strike and peak was less in the individuals with PFP compared with the healthy controls. In addition, there were trends towards individuals with PFP who had a delayed EMG onset of VL having reduced knee flexion during stair descent compared with PFP individuals with simultaneous vasti onsets and the control participants.

CONCLUSION

These results indicate that the amount of stance-phase knee flexion is lower in individuals with PFP and that this may be related to onset timing of the vasti.

Electromyography of the quadriceps in patellofemoral pain with patellar subluxation

This study compared muscle activity and timing of gait phases during functional activities in 13 subjects with patellofemoral pain associated with lateral subluxation and in 11 subjects with healthy knees. Fine wire electromyography recorded activity in the vastus lateralis and vastus medialis oblique during walking and ascending and descending stairs. Subjects were filmed to divide the activities into phases and determine timing. The vastus medialis oblique and vastus lateralis had similar patterns during all activities. Subjects with patellofemoral pain had significantly increased activity in the vastus medialis oblique and vastus lateralis compared with the healthy subjects during the most demanding phases of the gait cycle, suggesting a generalized quadriceps weakness in the patients with patellofemoral pain. Timing differences were seen in walking and stair ascending with the subjects with patellofemoral pain spending significantly more time in stance compared with the healthy subjects. This may be an attempt to reduce the load on weak quadriceps. These data reflect a generalized quadriceps muscle weakness, rather than the prevailing theory of quadriceps muscle imbalance as an etiology of patellofemoral pain. Therefore, we support the practice of strengthening the entire quadriceps muscle group, rather than attempting to specifically target the vastus medialis oblique.

A comparison of eccentric isokinetic torque production and velocity of knee flexion angle during step down in patellofemoral pain syndrome patients and unaffected subjects

OBJECTIVE

To determine knee angular velocity changes during stair descent and slow velocity eccentric isokinetic quadriceps contraction, in normal controls and patellofemoral pain syndrome patients.

DESIGN

Isokinetic and kinematic analysis of the performance of patellofemoral pain syndrome patients and matched normal controls.

BACKGROUND

In the presence of increased patellofemoral joint stresses, patellofemoral pain syndrome patients have been shown to adopt compensatory strategies to minimise joint loading and therefore pain. One of the compensatory strategies reported, is that of the break phenomena, which results in a change quadriceps torque production.

METHODS

Twenty female patients with patellofemoral pain syndrome and 20 asymptomatic matched controls participated in the study. All subjects had their isokinetic eccentric and concentric quadriceps torque assessed at 30 degrees/second and 2-dimensional video data taken when descending from a step. Variations in knee angular velocity and torque curves were then identified.

RESULTS

None of the subjects demonstrated a break on isokinetic concentric quadriceps contraction. Of the patellofemoral pain syndrome patients, 50% (10 out of 20) had a break in eccentric torque curve on testing, compared with 15% (3 out of 20) of the controls. Abnormal curve perturbation was demonstrated to occur in none of the controls isokinetically, but 20% (4 out 20) of the patellofemoral pain syndrome patients had perturbations in their torque curves. On stair decent a break was seen in 60% (12 out of 20) of the patellofemoral pain syndrome patients and 15% (3 out of 20) of the control subjects on analysis of the knee angular velocity. Twenty percent (4 out of 20) of the patellofemoral pain syndrome patients and 10% (2 out of 20) of the controls had abnormal curve perturbation on analysis of their stair descent.

CONCLUSIONS

The implications are that there appears to be a relationship between patellofemoral pain syndrome and control of eccentric quadriceps contraction. This relationship is possibly related to joint and soft tissue loading not just the degree of pain, with the break being a saving reflex to prevent further stress.

RELEVANCE

Exercise to rehabilitate the quadriceps in patellofemoral pain syndrome should be chosen with regard to joint loading and range of movement as well as velocity of contraction, in order to facilitate quadriceps activation as opposed to inhibiting it.

The effect of release of the popliteus and quadriceps force on rotation of the knee

The current study was done to determine whether an isolated, partial, or complete injury to the popliteus at the femur increases rotational knee laxity. The other aim was to determine how quadriceps loading affects internal and external rotation. Ten cadaver knee specimens with an intact posterolateral complex were held in a biomechanical testing rig at 0 degrees, 30 degrees, 60 degrees, and 90 degrees flexion. Movement of the tibia relative to the femur was measured while internal and external moments of 3 N-m were applied about the long axis of the tibia. Laxity was assessed for an intact specimen, and with partial and complete detachment of the popliteus femoral insertion. In five of the 10 specimens laxity additionally was assessed with sufficient quadriceps loading to resist 100 N vertical force at the hip. The results showed that partial and total release of the popliteus increased external laxity of the knee by as much as 6.6 degrees (90 degrees flexion) and by as much as 3.5 degrees (90 degrees flexion). Quadriceps loading reduced internal and external knee laxity significantly. Injury of the popliteus at the femoral insertion may be associated with increased rotational laxity of the knee. An increase in quadriceps force may be necessary to control increased external rotation of the tibia.

Therapeutic patellar taping changes the timing of vasti muscle activation in people with patellofemoral pain syndrome

OBJECTIVE

To examine the effect of the application of tape over the patella on the onset of electromyographic (EMG) activity of vastus medialis obliquus (VMO) relative to vastus lateralis (VL) in participants with and without patellofemoral pain syndrome (PFPS).

DESIGN

Randomised within subject.

SETTINGS

University laboratory.

PARTICIPANTS

Ten participants with PFPS and 12 asymptomatic controls.

INTERVENTIONS

Three experimental taping conditions: no tape, therapeutic tape, and placebo tape.

MAIN OUTCOME MEASURES

Electromyographic onset of VMO and VL assessed during the concentric and eccentric phases of a stair stepping task.

RESULTS

When participants with PFPS completed the stair stepping task, the application of therapeutic patellar tape was found to alter the temporal characteristics of VMO and VL activation, whereas placebo tape had no effect. In contrast, there was no change in the EMG onset of VMO and VL with the application of placebo or therapeutic tape to the knee in the asymptomatic participants.

CONCLUSIONS

These data support the use of patellar taping as an adjunct to rehabilitation in people with PFPS.

[Knee orthosis. First part : evaluation of physiological properties based on a review of the literature]

INTRODUCTION

The aim of this work was to proceed to a literature review to determine the physiological justifications underlying knee orthosis use in medical practice.

METHOD

An analysis of the international literature relating to the years 1980-2000 was carried out with the Medline data bank. We added extra articles focusing on the validity of the protocols used in the different evaluations.

RESULTS

Five hundred and twelve articles were selected and 46 articles of experimental validation were retained. The experimental protocols are divided into in vitro studies and clinical studies carried out in both healthy subject and patients. Only the in vitro experimental data allowed to reach strain values simulating traumatisms of the articular structures. They allowed to define the interest and limits of the orthosis according to articular physiology. Measurements carried out in vivo were effective to characterize the parameters of stability and proprioception and to discriminate between the orthosis. These studies correspond to experimental situations with related constraints that remain far below lesional constraints, focusing on their clinical validity.

CONCLUSION

This work point out many studies focusing on the physiological characterization of the knee orthosis. This evaluation of the orthosis through a single methodology remains difficult and justifies confrontation with clinical trials data.

American Academy of Pediatrics: Technical report: knee brace use in the young athlete

This statement is a revision of a previous statement on prophylactic knee bracing and provides information for pediatricians regarding the use of various types of knee braces, indications for the use of knee braces, and the background knowledge necessary to prescribe the use of knee braces for children.

Patellar taping: is clinical success supported by scientific evidence?

Patellofemoral pain syndrome (PFPS) is a common condition presenting to physiotherapy and sports medicine practices. Despite its prevalence, the aetiology, pathogenesis, and recommended treatment remain unclear. One component of treatment for PFPS that has been subjected to scrutiny is patellar taping. This taping was designed to realign the patella within the femoral trochlea, thus reducing pain from PFPS and improving both quadriceps and patellofemoral joint function. Clinical and research findings confirm that the pain associated with PFPS is significantly reduced with patellar taping. Therefore, research has aimed at determining the mechanisms of this pain relief. The means by which patellar tape can relieve pain may provide insight into the aetiology and risk factors for PFPS, thus allowing more appropriately designed treatment regimes and preventative strategies. There is evidence to suggest that patellar tape improves patella alignment (measured radiographically) and quadriceps function (torque production and extensor moments). Evidence that patellar tape enhances the activation of individual vastii (magnitude or timing) is limited in quality and quantity, which probably reflects the difficulties inherent in measuring this complex question. There is preliminary evidence for improved knee control during gait in association with patellar tape. This paper critically reviews the studies that have examined the effects of patellar taping and makes informed recommendations for further research and clinical practice.

Patellofemoral pain syndrome in the female athlete

Although PFS will continue to be a therapeutic challenge, the prognosis for most female athletes is good, especially if they are motivated and compliant with their treatment program. Particularly in women, care should be taken to avoid placing too much emphasis on biomechanical variants that may not be clinically significant or correctable because such findings can reinforce a feeling that "nothing can be done." In many cases, muscle dysfunction and repetitive loading of the patellofemoral joint rather than fixed biomechanical factors contribute to the development of PFS. Nonetheless, the importance of a detailed biomechanical assessment on physical examination must not be neglected, particularly in athletes who are not improving with conservative treatment and who may become surgical candidates. A practical initial treatment program for most athletes with nontraumatic PFS begins with relative rest, quadriceps strengthening, and stretching of tight myotendinous units. The introduction of NSAIDs, orthoses, taping, knee sleeves, and more specific rehabilitative exercises should be an individualized decision based on physical findings, past treatment results, and athletic expectations. Surgical referral should be considered in cases of PFS or patellar instability refractory to prolonged maximal nonoperative treatment.

Using patellofemoral braces for anterior knee pain

Disorders of the patellofemoral joint are common in recreational and competitive athletes. The pathophysiology of these disorders is unclear but may be related to malalignment of the patella and femoral trochlea, which may produce the characteristic anterior knee symptoms (1). Diagnosing and treating patellofemoral pain syndrome is challenging but important, since patellofemoral abnormalities can result in substantial discomfort and disability.

Effect of a patellar realignment brace on patients with patellar subluxation and dislocation. Evaluation with kinematic magnetic resonance imaging

The object of this study was to evaluate the effect of a patellar realignment brace on patients with patellar subluxation or dislocation. Twenty-one patients (24 patellofemoral joints) with clinical evidence of patellar subluxation (N = 16) or dislocation (N = 5) were examined with the joint inside a positioning device to allow active-motion, kinematic magnetic resonance imaging. To analyze the patellar tracking pattern, the same imaging parameters (patellar tilt angle, bisect offset, and lateral patellar displacement) and section locations were used before and after application of a patellar realignment brace. No statistically significant differences were found in any of the three parameters for the patellofemoral relationships before or after wearing the patellar brace. The results indicated no stabilizing effect of the tested brace in patients with patellar subluxation or dislocation during active joint motion.

Patellofemoral disorders: a classification system and clinical guidelines for nonoperative rehabilitation

Patellofemoral disorders are among the most common clinical conditions managed in the orthopaedic and sports medicine setting. Nonoperative intervention is typically the initial form of treatment for patellofemoral disorders; however, there is no consensus on the most effective method of treatment. Although numerous treatment options exist for patellofemoral patients, the indications and contraindications of each approach have not been well established. Additionally, there is no generally accepted classification scheme for patellofemoral disorders. In this paper, we will discuss a classification system to be used as the foundation for developing treatment strategies and interventions in the nonsurgical management of patients with patellofemoral pain and/or dysfunction. The classification system divides the patellofemoral disorders into eight groups, including: 1) patellar compression syndromes, 2) patellar instability, 3) biomechanical dysfunction, 4) direct patellar trauma, 5) soft tissue lesions, 6) overuse syndromes, 7) osteochondritis diseases, and 8) neurologic disorders. Treatment suggestions for each of the eight patellofemoral dysfunction categories will be briefly discussed.

The biomechanics of the patellofemoral joint

Physical therapy for patella malalignment differs from therapy for other knee conditions. In fact, accepted forms of knee therapy can be counterproductive when one is dealing with patella malalignment. This article reviews some of the biomechanical foundations of patella-specific therapy and addresses common controversies. We emphasize the concept of articular cartilage stress over that of joint reaction force. The rationale for strengthening the vastus medialis obliquus and for avoiding certain forms of open chain strengthening are discussed, and we outline some of the exciting work being done in our laboratory concerning patellofemoral tracking, contact area, and cartilage properties.