The role of quadriceps exercise in the treatment of patellofemoral pain syndrome

Effects of hip abductor with external rotator strengthening versus proprioceptive training on pain and functions in patients with patellofemoral pain syndrome: A randomized controlled trial

BACKGROUND

Strengthening the hip muscles, particularly the abductors and rotators, has been reported beneficial for treating Patellofemoral pain syndrome (PFPS). Proprioceptive training (PT) is also shown to improve musculoskeletal pain and function in PFPS. The most appropriate treatment from these 2 is unclear. This study aimed to compare the effects of hip abductors and external rotator strengthening exercises along with conventional physical therapy (CPT) vs the proprioceptive training of the knee along with CPT in patients with PFPS.

METHODS

Forty-five participants were divided into 3 groups, experimental group 1 (EG 1), experimental group 2 (EG 2), and control group (CG), with fifteen participants in each group. EG 1 received hip abductor and external rotator strengthening exercises in addition to CPT. EG 2 received proprioceptive training and CPT. CG received CPT alone. Intervention programs lasted for 4 weeks. The pain was measured by Kujala Anterior Knee Pain Scale (AKPS). The study was registered retrospectively in the protocol registration and results system (clinicaltrials.gov, ID: NCT05698797 on 26/01/2023).

RESULTS

AKPS scores significantly (P < .001) improved in all 3 groups. A significant (P < .05) difference was also observed between all 3 groups. The greatest improvement was observed in EG 1, followed by EG 2 and CG.

CONCLUSION

The addition of hip abductor and external rotator strengthening exercises to a 4-week CPT program showed a more significant improvement in AKPS scores than the addition of proprioceptive training in patients with PFPS.

Optimal Force Myography Placement For Maximizing Locomotion Classification Accuracy in Transfemoral Amputees: A Pilot Study

Force myography (FMG), is shown to be a promising alternative to electromyography in locomotion classification. However, the placement of force myography sensors over the thigh during locomotion is not yet clear. To this end, an inhouse developed FMG strap was placed over the thigh muscles of healthy/amputees, while walking on different terrains. The performance of the system was tested on six healthy and two amputees during the five different placements of FMG strap i.e., base, distal, lateral, medial, and proximal. The study reveals that there is an increase in average accuracy (STD) from [mean (STD)] 96.4% (4.0) to 99.5% (0.5) for healthy individuals and 95.5% (3.0) to 99.1% (0.3) for amputees while moving the FMG strap to the proximal of the thigh/stump. The study further determines the combination of three FMG channels on anterior side (Rectus Femoris, Vastus lateralis, and Iliotibial Tract muscles) that provides classification accuracy at par (p > 0.05) to utilizing all eight channels for locomotion classification. The variation of humidity throughout the trials did not significantly (p > 0.05) affect the classification accuracy. The study concludes that the optimal location to place the FMG strap is proximal to the thigh/ stump with a minimum of three FMG channels on the anterior part of the thigh for superior classification accuracy.

Biofeedback supplementation to physiotherapy exercise programme for rehabilitation of patellofemoral pain syndrome: a randomized controlled pilot study

Objectives: To examine the efficacy of electromyographic (EMG) biofeedback supplementation to exercise rehabilitation for people with patellofemoral pain syndrome.

Design: Double-blinded randomized clinical controlled pilot trial.

Setting: Clinical setting with home programme.

Participants: Twenty-six subjects diagnosed with patellofemoral pain.

Intervention: Subjects were randomly assigned into EMG biofeedback+exercise group or exercise-only group. All subjects participated in an eight-week home exercise programme, while the biofeedback group also received EMG visual feedback of their quadriceps muscle activities during the exercises.

Main outcome measures: Isokinetic knee extension strength, patellar alignments and perceived pain severity were assessed in weeks 0, 4 and 8 for all subjects. The data within and between groups were compared by repeated measures ANOVA with aα=0.05.

Results: Both groups improved in isokinetic peak torque (P=0.005), work output (P=0.037) and patellar alignments (P=0.001-0.014). Besides, there was a trend of decrease in pain (P=0.088). The biofeedback group improved faster than the exercise group in lateral patellar rotation and peak torque per body weight, although no statistically significant difference was shown.

Conclusion: Biofeedback supplement to the exercise programme might hasten the improvement for subjects with patellofemoral pain in the first few weeks of a physiotherapy exercise programme, but this needs further study before being used.

Localization of the Lateral Retinacular Nerve for Diagnostic and Therapeutic Nerve Block for Lateral Knee Pain: A Cadaveric Study

BACKGROUND

The lateral retinacular nerve (LRN) is a branch of the superior lateral genicular nerve (SLGN) and is believed to contribute to anterolateral knee pain. The precise anatomical pathway of the LRN, however, has not been demonstrated as it relates to the performance of targeted nerve block procedures.

OBJECTIVE

To describe the anatomical landmarks for localization of the LRN to facilitate diagnostic and therapeutic nerve blocks in the treatment of chronic anterolateral knee pain.

DESIGN

Descriptive study.

SETTING

Anatomy dissection laboratory in an academic institution.

METHODS

Twenty lower extremities were dissected in 12 cadavers. The sciatic nerve was identified, and its branch to the posterior aspect of the knee, the SLGN, was dissected. The SLGN dissection was continued distally to identify its first branch, the LRN. Two measurements were taken from the branch point on the lateral knee deep to the distal biceps tendon in alignment with the fibular head. A validation study completed in 4 knees was performed as follows: 1 mL of colored dye was injected at the first and second measurements. The cadaveric knee was then dissected to assess the accuracy.

MAIN OUTCOME MEASUREMENTS

Localization of the branch point of the LRN from the SLGN via dissection and then direct assessment of injected dye at the measurement points via dissection.

RESULTS

The branch point of the LRN from the SLGN was, on average, 5.5 ± 0.66 cm (with a range of 4.5-7.0 cm) proximal to the lateral tibiofemoral joint line in line with the head of the fibula and 2.6 ± 0.62 cm (2.0-4.5 cm) proximal to the tip of the lateral femoral epicondyle. On assessment of the 2 measurements, the measurement 5.5 cm proximal to the lateral joint line accurately targeted the branch point in 100% (4/4) of the knees, whereas the measurement 2.6 cm proximal the tip of the lateral femoral epicondyle accurately targeted the branch point in 75% (3/4) of the knees.

CONCLUSION

The results of this study provide 2 dependable landmarks and a description of the path of the LRN, making it possible to accurately target the LRN to diagnose and alleviate lateral knee pain.

Range of motion and leg rotation affect electromyography activation levels of the superficial quadriceps muscles during leg extension

Leg extension (LE) is commonly used to strengthen the quadriceps muscles during training and rehabilitation. This study examined the effects of limb position (POS) and range of motion (ROM) on quadriceps electromyography (EMG) during 8 repetitions (REP) of LE. Twenty-four participants performed 8 LE REP at their 8 repetition maximum with lower limbs medially rotated (TI), laterally rotated (TO), and neutral (NEU). Each REP EMG was averaged over the first, middle, and final 0.524 rad ROM. For vastus medialis oblique (VMO), a REP × ROM interaction was detected (p < 0.02). The middle 0.524 rad produced significantly higher EMG than the initial 0.524 rad for REP 6-8 and the final 0.524 rad produced higher EMG than the initial 0.524 rad for REP 1, 2, 3, 4, 6, and 8 (p ≤ 0.05). For rectus femoris (RF), EMG activity increased across REP with TO generating the greatest activity (p < 0.001). For vastus lateralis (VL), EMG increased across REP (p < 0.001) with NEU and TO EMG increasing linearly throughout ROM and TI activity greatest during the middle 0.524 rad. We conclude that to target the VMO, the optimal ROM is the final 1.047 rad regardless of POS, while maximum EMG for the RF is generated using TO regardless of ROM. In contrast, the VL is maximally activated using TI over the first 1.047 rad ROM or in NEU over the final 0.524 rad ROM.

Patellar taping for patellofemoral pain syndrome in adults

BACKGROUND

Patellofemoral pain syndrome refers to the clinical presentation of knee pain related to changes in the patellofemoral joint. Patellofemoral pain syndrome usually has a gradual onset of pain with none of the features associated with other knee diseases or trauma. It is often treated by physiotherapists, who use a variety of techniques including patellar taping. This involves the application of adhesive sports medical tape applied directly to the skin over the patella on the front of the knee. Patients often report an instantaneous improvement in pain and function after the tape is applied, but its longer term effects are uncertain.

OBJECTIVES

The objective was to assess the effects, primarily on pain and function, of patellar taping for treating patellofemoral pain syndrome in adults.

SEARCH METHODS

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register, the Cochrane Central Register of Controlled Trials, MEDLINE, CINAHL, EMBASE, PEDro, SPORTDiscus, AMED, reference lists of articles, trial registers and conference proceedings. All were searched to August 2011.

SELECTION CRITERIA

Randomised controlled trials and quasi-randomised controlled trials testing the effects of patellar taping on clinically relevant outcomes, pain and function, in adults with patellofemoral pain syndrome. We excluded studies testing only the immediate effects of tape application.

DATA COLLECTION AND ANALYSIS

Both review authors independently performed study selection, data extraction and assessment of risk of bias. Trialists were contacted for more information. Data were pooled where possible.

MAIN RESULTS

Five small heterogeneous randomised controlled trials, all at high risk of performance bias and most at risk of at least one other type of bias, were included. These involved approximately 200 participants with a diagnosis of patellofemoral pain syndrome. All compared taping versus control (no or placebo taping) and all included one or more co-interventions given to both taping and control group participants; this was prescribed exercise in four trials. The intensity and length of treatment was very varied: for example, length of treatment ranged from one week in one trial to three months in another. A meta-analysis of the visual analogue scale (VAS) pain data (scale 0 to 10: worst pain), measured in different ways, from four trials (data from 161 knees), found no statistically or clinically significant difference between taping and non taping in pain at the end of the treatment programmes (mean difference (MD) -0.15; 95% confidence interval (CI) -1.15 to 0.85; random-effects model used given the significant heterogeneity (P < 0.0001)). Data for other outcomes measuring function and activities of daily living were from single trials only and gave contradictory results.

AUTHORS' CONCLUSIONS

The currently available evidence from trials reporting clinically relevant outcomes is low quality and insufficient to draw conclusions on the effects of taping, whether used on its own or as part of a treatment programme. Further research involving large, preferably multi-centre, good quality and well reported randomised controlled trials that measure clinically important outcomes and long-term results is warranted. Before this, consensus is required on the diagnosis of patellofemoral pain syndrome, the standardisation of outcome measurement and an acceptable approach for patellar taping.

Benefits of custom-made foot orthoses in treating patellofemoral pain

BACKGROUND

Patellofemoral pain is one of the most common disorders affecting the knee. Forefoot varus and excessive subtalar pronation can be associated with patellofemoral pain. Foot orthotics may produce an improvement in symptoms.

OBJECTIVES

The aim of this study was to test whether patellofemoral pain is improved after four weeks of using custom-made foot orthoses.

STUDY DESIGN

Clinical trial without control group.

METHODS

Twenty-one subjects with patellofemoral pain were given custom-made foot orthoses (2-mm thick polypropylene and 4-mm thick polyethylene foam liner of 45 shore A hardness). Patellofemoral pain was evaluated with a visual analogue scale before applying the treatment, and at two weeks and four weeks follow-up. At the two-week check-up, a forefoot varus posting was added to the orthoses.

RESULTS

Improvements in patellofemoral pain was significant in all comparisons: initial pain with pain at the two-week check-up (P < 0.001), initial pain with pain at four weeks (P < 0.001), and pain at two weeks with pain at four weeks (P < 0.001). The effect size was large in all comparisons.

CONCLUSION

For the participants in this study, the custom-made foot orthoses were found to be an effective conservative treatment to reduce the symptoms 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.

Training program and additional electric muscle stimulation for patellofemoral pain syndrome: a pilot study

OBJECTIVES

To evaluate the beneficial effect of training in patients with patellofemoral pain syndrome (PFPS) and influence of additional electric muscle stimulation (EMS) of the knee extensor muscles.

DESIGN

A randomized clinical trial.

SETTING

Supervised physiotherapy (PT) training and home-based EMS.

PARTICIPANTS

Patients (N=38; 14 men, 24 women) with bilateral PFPS.

INTERVENTIONS

One group (PT) received supervised PT training for 12 weeks. The other received PT and EMS. The stimulation protocol was applied to the knee extensors for 20 minutes, 2 times daily, 5 times a week for 12 weeks at 40 Hz, with a pulse duration of .2 6ms, at 5 seconds on and 10 seconds off. Maximal tolerable stimulation intensity was up to 80 mA.

MAIN OUTCOME MEASURES

Patellofemoral pain assessment with visual analog scale during activities of daily life, Kujala patellofemoral score, and isometric strength measurement before and after 12 weeks treatment as well as after 1 year.

RESULTS

Thirty-six patients completed the 12-week follow-up. There was a statistically significant reduction of pain in both groups (PT group, P=.003; PT and EMS group, P<.001) and significant improvement of the Kujala score in both groups (PT group, P<.001; PT and EMS group, P<.001) after 12 weeks of treatment with improvement of function and reduction of pain at the 1-year follow-up. The difference between the 2 treatment groups was statistically not significant. We could not measure any significant change in isometric knee extensor strength in either group.

CONCLUSIONS

A supervised PT program can reduce pain and improve function in patients with PFPS. We did not detect a significant additional effect of EMS with the protocol described previously.

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.

Effect of shoe heel height on vastus medialis and vastus lateralis electromyographic activity during sit to stand

Background

It has been proposed that high-heeled shoes may contribute to the development and progression of knee pain. However, surprisingly little research has been carried out on how shoe heel height affects muscle activity around the knee joint. The purpose of this study was to investigate the effect of differing heel height on the electromyographic (EMG) activity in vastus medialis (VM) and vastus lateralis (VL) during a sit to stand activity. This was an exploratory study to inform future research.

Methods

A repeated measures design was used. Twenty five healthy females carried out a standardised sit to stand activity under 4 conditions; barefoot, and with heel wedges of 1, 3, and 5 cm in height. EMG activity was recorded from VM and VL during the activity. Data were analysed using 1 × 4 repeated measures ANOVA.

Results

Average rectified EMG activity differed with heel height in both VM (F_{2.2, 51.7} = 5.24, p < 0.01), and VL (F_{3, 72} = 5.32, p < 0.01). However the VM: VL EMG ratio was not significantly different between conditions (F_{3, 72} = 0.61, p = 0.609).

Conclusion

We found that as heel height increased, there was an increase in EMG activity in both VM and VL, but no change in the relative EMG intensity of VM and VL as measured by the VM: VL ratio. This showed that no VM: VL imbalance was elicited. This study provides information that will inform future research on how heel height affects muscle activity around the knee joint.

Analysis on the activation of the VMO and VLL muscles during semisquat exercises with and without hip adduction in individuals with patellofemoral pain syndrome

OBJECTIVE

The purpose of this study was to investigate the effect of hip adduction on the activity of the Vastus Medialis Obliquus (VMO) and Vastus Lateralis Longus (VLL) muscles during semisquat exercises.

METHODS

Twenty female subjects, divided into two groups comprising healthy and patellofemoral pain syndrome (PFPS) subjects (ten volunteers for each group), performed three double-leg semisquat exercise trials with maximum hip adduction isometric contraction (DLSS-HA) and three double-leg semisquat exercise trials without hip adduction (DLSS). The normalized electromyographic muscle data were analysed using Repeated Measure ANOVA (p<or=0.05).

RESULTS

The electrical activity of both VMO and VLL muscles was significantly greater during DLSS-HA exercise than during DLSS (p=0.0002) for both groups. Additionally, an independent Repeated Measure ANOVA revealed that the electric activity of the VLL muscle was significantly greater (p=0.0149) than that of the VMO muscle during DLSS exercises only for the PFPS group. However, no differences were found during DLSS-HA exercises.

CONCLUSIONS

Although there was no preferential VMO muscle activation, the association of hip adduction with squat exercise promoted a greater balance between the medial and lateral portions of the quadriceps femoris muscle and could be indicated for the conservatory treatment of PFPS patients. The association of isometric hip adduction with isometric semisquat exercises produced a more overall quadriceps activity and could be indicated for clinical rehabilitation or muscle strengthening programs.

Quadriceps force generation in patients with osteoarthritis of the knee and asymptomatic participants during patellar tendon reflex reactions: an exploratory cross-sectional study

Background

It has been postulated that muscle contraction is slower in patients with osteoarthritis of the knee than asymptomatic individuals, a factor that could theoretically impair joint protection mechanisms. This study investigated whether patients with osteoarthritis of the knee took longer than asymptomatic participants to generate force during reflex quadriceps muscle contraction. This was an exploratory study to inform sample size for future studies.

Methods

An exploratory observational cross sectional study was carried out. Two subject groups were tested, asymptomatic participants (n = 17), mean (SD) 56.7 (8.6) years, and patients with osteoarthritis of the knee, diagnosed by an orthopaedic surgeon, (n = 16), age 65.9 (7.8) years. Patellar tendon reflex responses were elicited from participants and measured with a load cell. Force latency, contraction time, and force of the reflex response were determined from digitally stored data. The Mann-Whitney U test was used for the between group comparisons in these variables. Bland and Altman within-subject standard deviation values were calculated to evaluate the measurement error or precision of force latency and contraction time.

Results

No significant differences were found between the groups for force latency (p = 0.47), contraction time (p = 0.91), or force (p = 0.72). The two standard deviation measurement error values for force latency were 27.9 ms for asymptomatic participants and 16.4 ms for OA knee patients. For contraction time, these values were 29.3 ms for asymptomatic participants and 28.1 ms for OA knee patients. Post hoc calculations revealed that the study was adequately powered (80%) to detect a difference between the groups of 30 ms in force latency. However it was inadequately powered (59%) to detect this same difference in contraction time, and 28 participants would be required in each group to reach 80% power.

Conclusion

Patients with osteoarthritis of the knee do not appear to have compromised temporal parameters or magnitude of force generation during patellar tendon reflex reactions when compared to a group of asymptomatic participants. However, these results suggest that larger studies are carried out to investigate this area further.

In vivo and noninvasive load sharing among the vasti in patellar malalignment

PURPOSE

It is not clear how the knee extension torque is distributed quantitatively among the lateral and medial vasti in patellofemoral pain (PFP) patients with patellar malalignment, which was investigated in vivo and noninvasively in ten PFP patients and eleven controls. We hypothesized that the vastus medialis oblique (VMO) and vastus medialis longus (VML) of PFP patients contribute less to knee extension than that in controls.

METHODS

Electrical stimulation was used to activate each vastus component selectively. The relationship between the knee extension torque generated by each individual vastus component and the corresponding compound muscle action potential (M-wave) was established over different contraction levels, which was used to calibrate the corresponding voluntary EMG signal and determine torque ratios of VMO/VL (vastus lateralis), VMO/VML, VML/VL and (VMO+VML)NL during voluntary isometric knee extension.

RESULTS

The VMO and VML of PFP patients contributed significantly less to knee extension than their counterparts in controls. The combination of VMO and VML generated comparable amount of extension torque as the VL in the controls, while it produced significantly lower extension torque than that of the VL in the PFP patients. In addition, the VMO/VL was lower than VMO/VML and VML/VL in both PFP and control groups.

CONCLUSIONS

Compared to controls, the VMO and VML in the PFP patients contributed significantly less to the knee extension torque. The approach can be used to investigate load sharing among quadriceps muscles in vivo and noninvasively, in both healthy subjects and patients with patellofemoral disorder and patellar malalignment.

Effects of foot orthoses on quality of life for individuals with patellofemoral pain syndrome

STUDY DESIGN

Repeated-measures analysis of intervention.

OBJECTIVES

To determine the effects of foot orthoses on quality of life for individuals with patellofemoral pain who demonstrate excessive foot pronation.

BACKGROUND

Foot orthoses are a common intervention for patients with patellofemoral pain. Limited information is available, however, regarding the effects of foot orthoses on quality of life for these patients.

METHODS AND MEASURES

Sixteen subjects with patellofemoral pain who also exhibited signs of excessive foot pronation were studied. Subjects underwent a 2-week period of baseline study followed by custom foot orthotic intervention. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was administered to subjects at the time of screening, just prior to foot orthotic intervention, and at 2 weeks and 3 months following foot orthotic intervention.

RESULTS

Wilcoxon matched-pairs signed-rank test results indicated statistically significant improvements in the pain and stiffness subscales 2 weeks following the start of foot orthotic intervention. All WOMAC subscale scores were significantly improved at 3 months compared with preintervention measurements.

CONCLUSIONS

Custom-fitted foot orthoses may improve patellofemoral pain symptoms for patients who demonstrate excessive foot pronation.

In vivo load sharing among the quadriceps components

Knee extension is always performed with coordinated contractions of multiple quadriceps muscle components; however, how the load is shared among them under normal and pathological conditions is unclear. We hypothesized that: the absolute moment generated by each quadriceps component increases with the total knee extension moment; the relative contribution and its dependence on the total knee extension moment are different for different quadriceps components; and the centrally located large vastus intermedius (VI) is favored by the central nervous system at low levels of activation. Electrical stimulation was used to activate each quadriceps component selectively in six human subjects. The relationship between the knee extension moment generated by an individual quadriceps component and the corresponding compound muscular action potential (M-wave) over various contraction levels was established for each quadriceps component. This relationship was used to calibrate the corresponding EMG signal and determine load sharing among quadriceps components during submaximal isometric voluntary knee extension. The VI contributed the most (51.8-39.6%) and vastus medialis the least (9.5-12.2%) to knee extension moment (P<0.05). As the knee extension moment increased, the relative contribution of the VI decreased (P=0.017) while the relation contribution of the vastus lateralis and medialis increased (P</=0.012). The absolute moment generated by each quadriceps component always increased with the total knee extension moment (P<0.002). Our in vivo approach determined subject- and condition-specific load sharing among individual muscles and showed that the central nervous system utilized the centrally located, uniarticular VI in submaximal isometric knee extension.

A critical reexamination of the morphology, neurovasculature, and fiber architecture of knee extensor muscles in animal models and humans

The purposes of the present study were to resolve a number of major inconsistencies found in the literature on the structure of the quadriceps femoris muscle and to extend knowledge of its structure using descriptive, qualitative methodology. The quadriceps femoris muscle was investigated in 41 cats, and the findings were confirmed in 6 human cadavers. Two aponeuroses with major biomechanical functions (rectus-vastus and vastus aponeurosis), neither of which had been previously described in the literature, were characterized in both species. The study also resolved many major inconsistencies in the literature: The muscle sometimes described as vastus intermedius (VI) was found to be the articularis genu, the muscle sometimes described as vastus medialis (VM) was found to be the VI, the rectus femoris head was found to have an additional proximal nerve branch not previously recognized, no anomalous 5th head was everfound, and the distal VM were not found to have 2 heads (in either cats or humans). The authors' anatomical descriptions and bimechanical models of the muscles, tendons, and neurovascular should provide a helpful foundation for future studies on the quadriceps. Two general recommendations are made: 1) that the feline model be considered a viable model to elucidate human knee pathomechanics; and 2) that regardless of the anatomical structure of interest, orthopedic nurses, orthopedic surgeons, and research investigators should routinely use the research literature for anatomical guidance instead of standard anatomical textbooks.

A comparison of two types of electrical stimulation of the quadriceps in the treatment of patellofemoral pain syndrome. A pilot study

OBJECTIVE

To compare a commercially available electrical muscle stimulation regime with a new form of stimulation for the rehabilitation of the quadriceps in patients with patellofemoral pain syndrome.

SETTING

A research facility within a teaching hospital.

METHODS

Sixteen patients (four men, 12 women) with patellofemoral pain, demonstrable quadriceps atrophy, but normal gait parameters were randomly allocated to one of two treatment groups. One group received a sequential mixed frequency stimulation pattern from a standard device. The other group received a new form of stimulation from an experimental stimulation device that contained simultaneous mixed frequency components.

OUTCOME MEASURES

Isometric and isokinetic extension torque, muscle fatigue rate, pain, functional questionnaire, step test, knee flexion, and quadriceps cross-sectional area.

RESULTS

These showed significant improvements for both groups after treatment (p < 0.05) in all outcome measures except flexion and fatigue rates, but no significant differences between the two stimulation regimes (p > 0.05).

CONCLUSION

Both stimulators performed similarly on patients with patellofemoral pain giving significant improvements for all patients for muscle strength, pain, self-reporting function and step testing. There were no significant differences between the two types of stimulation.

Electromyographic fatigue characteristics of the quadriceps in patellofemoral pain syndrome

This study compared the fatigue characteristics of the vastus medialis oblique (VMO), vastus lateralis (VL) and rectus femoris (RF) muscles. Ten healthy subjects with 10 patients with patellofemoral pain syndrome (PFPS) performed an isometric leg press for 60 seconds at 60% MVIC with data collected using surface EMG. The power spectrum was analyzed and the extracted median frequency normalised to calculate a linear regression slope for each muscle. A repeated measures ANOVA revealed no significant differences, neither between the groups (P=0.592) nor the muscles (P=0.434). However, the slopes for the VMO and VL were different between the two groups with similar slopes for the RF. There was much larger variability of MF values in the PFPS group. The VMO:VL ratio calculated from these slopes for the healthy subjects was 1.17 and for the PFPS group was 1.78. These results may indicate unusual features in the fatigue indices of the quadriceps in PFPS.

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.

Patellofemoral pain syndrome: a review of current issues

There is no clear consensus in the literature concerning the terminology, aetiology and treatment for pain in the anterior part of the knee. The term 'anterior knee pain' is suggested to encompass all pain-related problems. By excluding anterior knee pain due to intra-articular pathology, peripatellar tendinitis or bursitis, plica syndromes, Sinding Larsen's disease, Osgood Schlatter's disease, neuromas and other rarely occurring pathologies, it is suggested that remaining patients with a clinical presentation of anterior knee pain could be diagnosed with patello-femoral pain syndrome (PFPS). Three major contributing factors of PFPS are discussed: (i) malalignment of the lower extremity and/or the patella; (ii) muscular imbalance of the lower extremity; and (iii) overactivity. The significance of lower extremity alignment factors and pathological limits needs further investigation. It is possible that the definitions used for malalignment should be re-evaluated, as the scientific support is very weak for determining when alignment is normal and when there is malalignment. Consequently, pathological limits must be clarified, along with evaluation of risk factors for acquiring PFPS. Muscle tightness and muscular imbalance of the lower extremity muscles with decreased strength due to hypotrophy or inhibition have been suggested, but remain unclear as potential causes of PFPS. Decreased knee extensor strength is a common finding in patients with PFPS. Various patterns of weaknesses have been reported, with selective weakness in eccentric muscle strength, within the quadriceps muscle and in terminal knee extension. The significance of muscle function in a closed versus open kinetic chain has been discussed, but is far from well investigated. It is clear that further studies are necessary in order to establish the significance of various strength deficits and muscular imbalances, and to clarify whether a specific disturbance in muscular activation is a cause or an effect (or both) of PFPS. The most common symptoms in patients with PFPS are pain during and after physical activity, during bodyweight loading of the lower extremities in walking up/down stairs and squatting, and in sitting with the knees flexed. However, the source of patellofemoral pain in patients with PFPS cannot be sufficiently explained. There are several types of clinical manifestation of pain, and therefore a differentiated documentation of the patient's pain symptoms is necessary. The connection between strength, pain and inhibition, as well as between personality and pain, needs further investigation. Many different treatment protocols are described in the literature and recent studies advocate a comprehensive treatment approach allowing for an individual and specifically designed treatment. Surgical treatment is rarely indicated. It is strongly suggested that, when presenting studies on PFPS, a detailed description should be provided of the diagnosis, inclusion and exclusion criteria of the patients should be specified along with a detailed methodology, and the conclusions drawn should be compared with those of other studies in the published literature. As this is not the case in most studies on PFPS found in the literature, it is only possible to make general comparisons. In order to further develop treatment models for PFPS we advocate prospective, randomised, controlled, long term studies using validated outcome measures. However, there is a strong need for basic research on the nature and aetiology of PFPS in order to better understand this mysterious syndrome.

An outcome study of chronic patellofemoral pain syndrome. Seven-year follow-up of patients in a randomized, controlled trial

BACKGROUND

We determined prospectively the long-term outcomes of nonoperative treatment of chronic patellofemoral pain syndrome.

METHODS

Of forty-nine patients in a prospective, randomized, double-blind study of unilateral chronic patellofemoral pain syndrome in the knee, forty-five were reexamined seven years after the initial trial of treatment. In the earlier trial, the short-term (six-month) effects of intra-articular injections of glycosaminoglycan polysulfate combined with intensive quadriceps-muscle exercises were compared with those of injections of a placebo combined with exercises and with those of exercises alone. At seven years, the follow-up consisted of standardized subjective, functional, and clinical assessments and muscle-strength measurements as well as magnetic resonance imaging, radiography, and bone-densitometry measurements of the knee.

RESULTS

At six months, complete subjective, functional, and clinical recovery had occurred in almost three-fourths of the patients and, with the numbers available for study, neither significant nor clinically important differences among the three initial treatment groups were detected. The subjective and functional parameters showed few changes between six months and seven years; almost three-fourths of the patients still had full subjective and functional recovery at the time of the latest follow-up. However, according to the physician's clinical evaluation, the number of patients who had no symptoms on the patellar compression and apprehension tests decreased over time, from forty-two (93 percent) and forty (89 percent) of forty-five patients at six months to thirty (67 percent) and thirty-one (69 percent) at seven years; these changes were significant (p = 0.002 and p = 0.023, respectively). The number of patients who had crepitation on the patellar compression test increased over time, from twenty-six (58 percent) at six months to thirty-six (80 percent) at seven years (p = 0.021). The physician's overall assessment showed a similar trend, with thirty-four patients (76 percent) having had complete recovery at six months compared with thirty (67 percent) at seven years; however, with the numbers available, this change was not significant (p = 0.420). Magnetic resonance imaging, performed for thirty-seven patients, revealed no abnormalities in twenty-four (65 percent), mild abnormalities in four (11 percent), moderate abnormalities (a 25 to 75 percent decrease in the thickness of the cartilage) in seven (19 percent), and overt patellofemoral osteoarthritis in two (5 percent) at seven years.

CONCLUSIONS

The seven-year overall outcome was good in approximately two-thirds of the patients. However, the remaining patients still had symptoms or objective signs of a patellofemoral abnormality.

Which factors predict the long-term outcome in chronic patellofemoral pain syndrome? A 7-yr prospective follow-up study

PURPOSE

The aim of this prospective study was to determine which factors predict the long-term (7-yr) outcome of conservative treatment of chronic patellofemoral pain syndrome.

METHODS

The general predictors registered were age, gender, body composition, athletic activity, duration of symptoms, and follow-up time. The remaining 13 predictors were clinical or radiological measurements of the knee joint. In 45 consecutive patients, these predictors were measured at the beginning of the 6-wk treatment protocol (rest, NSAID, and intense isometric quadriceps exercises) and at the end of the follow-up. The outcome criteria were the 100-mm Visual Analog Scale (VAS) pain score, and the Lysholm and Tegner functional knee scores.

RESULTS

The extension strength of the affected knee was a significant predictor of the outcome scores (Lysholm score: r = 0.37, P < 0.05, and the Tegner score: r = 0.39, P < 0.01): the smaller the strength difference between the affected and unaffected knee, the better the outcome. In a multiple stepwise regression analysis, the variables pain in the patella apprehension test, patella crepitation at baseline and at follow-up, bilateral symptoms developed during the follow-up, and patient's age and height were also independent predictors of the final outcome and could together account 60% for the variation seen in the Lysholm score and 52% in the Tegner score, respectively. Neither the radiologic nor the magnetic resonance imaging changes at the affected knee had a clear association with the 7-yr outcome.

CONCLUSIONS

The results of the current and our previous (15) observations support the concept that restoration of good quadriceps strength and function to the affected extremity is important for good recovery of the patient. In addition, negative findings in the clinical tests of patellar pain and crepitation, nonappearance of bilateral symptoms during the follow-up, low body height, and young age are associated with good long-term outcome.

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.

Medial and Lateral Quadriceps Muscle Activity during Weight-Bearing Knee Extension Exercise

The purpose of this study was to determine the effect of weight-bearing terminal knee extension (WBKE) on normalized mean electromyographic (EMG) activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) and the VMO/VL ratio. Sixteen subjects with no history of knee dysfunction participated. Surface EMG data were recorded from the VMO and VL of subjects' test legs as they performed the WBKE exercise under four conditions, three involving elastic resistance and one involving no elastic resistance. EMG data were normalized relative to a maximal isometric quadriceps contraction, and overall mean VMO and VL activity and the VMO/VL ratio were determined for all conditions. The three conditions utilizing elastic resistance showed higher mean VMO and VL activity than the no-resistance condition. The VMO/ VL ratio was not significantly altered during any exercise condition as compared to maximal, quadriceps setting exercise. WBKE against elastic resistance was superior to the same exercise without resistance for generating mean VMO and VL activity. Performance of the WBKE, regardless of the position of lower extremity rotation, does not selectively activate the VMO apart from, or to a greater degree than, the VL.

Musculoskeletal injuries in adolescents

This article reviews the anatomy of the physis and the most common classification of injuries or fractures through the physis. The common apophyseal injuries of Osgood-Schlatter, Severs disease and iliac apophysitis, are reviewed in addition to a review of the most common osteochondritides, including Panner's disease and Osteochondritis Dessicans of the femur and talus. An understanding of these is key to diagnosis and treatment of adolescent musculoskeletal injuries. This article also reviews slipped capital femoral epiphysis, little leaguer's elbow, anterior cruciate and collateral ligament injuries, patella problems, ankle sprains and several common fractures in children.