The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective

Lower extremity jumping mechanics of female athletes with and without patellofemoral pain before and after exertion

BACKGROUND

Patellofemoral pain is especially common among female athletes and is traditionally associated with lower extremity mechanics thought to increase retropatellar stress. These detrimental mechanics may increase with exertion.

HYPOTHESIS

Differences in lower extremity mechanics during single-legged jumps between female athletes with and without patellofemoral pain will increase after exertion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty women with patellofemoral pain and 20 healthy female controls participated in a functional lower extremity exertion protocol of repetitive single-legged jumps. Pain, exertion, hip and trunk strength, and 3-dimensional lower extremity joint mechanics were recorded at the beginning and end of the protocol.

RESULTS

The patellofemoral pain group reported increased pain at the conclusion of the protocol. However, all subjects terminated the protocol due to complaints of fatigue. Mean strength measurements for the patellofemoral pain group were 24% lower for lateral trunk flexion (P = .06), 13% lower for hip abduction (P = .09), and 14% lower for hip external rotation (P = .03) than for controls. Subjects with patellofemoral pain demonstrated greater contralateral pelvic drop at the end of the exertion protocol compared with the control group (P = .003). Group differences in lower extremity mechanics, including increased hip adduction angle, hip flexion angle, hip abduction angular impulse, and decreased hip internal rotation angles, were observed among women with patellofemoral pain throughout the exertion protocol. These group differences were consistent despite increased pain for the patellofemoral pain group after exertion. Both groups demonstrated decreased jump height, hip flexion and internal rotation, knee flexion, and hip extension impulse at the end of the protocol.

CONCLUSION

Women with patellofemoral pain demonstrated lower extremity mechanics that differed from the healthy control group during single-legged jumping, particularly at the hip. These differences do not appear to vary with exertion level or pain among patellofemoral pain subjects during single-legged jumps.

CLINICAL RELEVANCE

Lower extremity jumping mechanics appear to be consistently different among women with patellofemoral pain. Conservative treatment programs that include kinematic retraining as well as hip and trunk strengthening may improve patient outcomes and prevent recurrence of this common orthopaedic condition.

Proximal and distal influences on hip and knee kinematics in runners with patellofemoral pain during a prolonged run

STUDY DESIGN

Cross-sectional experimental laboratory study.

OBJECTIVES

To investigate the relationships between hip strength and hip kinematics, and between arch structure and knee kinematics during prolonged treadmill running in runners with and without patellofemoral pain syndrome (PFPS).

BACKGROUND

Hip weakness can lead to excessive femoral motions that adversely affect patellofemoral joint mechanics. Similarly, foot mechanics, which are influenced by foot structure, are also known to influence patellofemoral joint mechanics. Thus, proximal and distal factors should be considered when studying individuals with PFPS.

METHODS AND MEASURES

Twenty recreational runners with PFPS (5 male, 15 female) and 20 matched uninjured runners participated in the study. Hip abduction and hip external rotation isometric strength measurements were collected before and after a prolonged run, while the arch height index was recorded on all runners before the run. Lower extremity kinematic data were collected at the beginning and end of the run. Two-way repeated-measures analyses of variance (ANOVAs) were used for analysis.

RESULTS

Both groups displayed decreases in hip abductor and external rotator strengths at the end of the run. The PFPS group displayed significantly lower hip abduction strength [(kg x cm)/body mass] compared to controls (PFPS group: begin 15.3, end 13.5; uninjured group: begin 17.3, end 15.4). At the end of the run, the level of association between hip abduction strength and the peak hip adduction angle for the PFPS group was statistically significant, indicating a strong relationship (r = -0.74). No other associations with hip strength were observed in either group. Arch height did not differ between groups and no significant association was observed between arch height and peak knee adduction angle during running.

CONCLUSIONS

Runners with PFPS displayed weaker hip abductor muscles that were associated with an increase in hip adduction during running. This relationship became more pronounced at the end of the run.

LEVEL OF EVIDENCE

Therapy, level 5.

Process for applying the international classification of functioning, disability and health model to a patient with patellar dislocation

BACKGROUND AND PURPOSE

The International Classification of Functioning, Disability and Health (ICF) has been proposed as a possible framework for organizing physical therapist practice. The purpose of this case report is to describe an evaluative and diagnostic process that is based on the ICF framework for a patient with a patellar dislocation.

CASE DESCRIPTION

The patient was a 23-year-old woman who sustained a right knee and patellofemoral joint injury, resulting in a sprain of the medial collateral ligament and a suspected sprain of the medial patellofemoral ligament. Evaluation at 4 weeks demonstrated a primary impairment of patellar instability associated with the primary activity limitation of limited walking distances. A plan of care to address impairments, activity limitations, and participation restrictions was developed, with modifications made on the basis of the patient's health condition and personal and environmental factors.

OUTCOMES

The patient attained all of her goals for therapy and was able to return to her normal activities and recreational pursuits without a recurrence of a patellar dislocation. Lower-Extremity Function Scale scores increased from 30 out of 80 to 76 out of 80 during the course of treatment.

DISCUSSION

The ICF model has been proposed as a framework for developing diagnostic classifications for rehabilitation professionals. The ICF model also should be assessed with regard to whether it provides a useful process for clinical decision making. The ICF model directs practitioners to address patients' problems at the level of the whole person, with modifications made on the basis of health conditions and personal and environmental factors.

Patellofemoral syndrome a paradigm for current surgical strategies

The literature regarding suggested treatments for patellofemoral problems is often conflicting and confusing. In this discussion I present the approach I take in evaluating and considering surgery for patients with any of a wide variety of anterior knee pain problems. It has been useful to concentrate on the biomechanics--the mechanical consequence to each tissue affected by any surgical change. In the proposed paradigm, it is assumed that pain is the result of an abnormal load--related either to tension or compression--being applied to each tissue in question. The challenge is to understand how and why that abnormal load was generated. It is essential to make an independent assessment of the condition of the lower limb skeleton, the patellofemoral ligaments, and the trochlear and patellar articular cartilage in each patient. While only a long book can address this subject in detail, this discussion provides a guide for formulating an analysis of the key issues when planning the operative treatment of patellofemoral pain and dysfunction.

Lumbopelvic manipulation for the treatment of patients with patellofemoral pain syndrome: development of a clinical prediction rule

STUDY DESIGN

Prospective cohort/predictive validity study.

OBJECTIVE

To determine the predictive validity of selected clinical exam items and to develop a clinical prediction rule (CPR) to determine which patients with patellofemoral pain syndrome (PFPS) have a positive immediate response to lumbopelvic manipulation.

BACKGROUND

Quadriceps muscle function in patients with PFPS was recently shown to improve following treatment with lumbopelvic manipulation. No previous study has determined if individuals with PFPS experience symptomatic relief of activity-related pain immediately following this manipulation technique.

METHODS AND MEASURES

Fifty subjects (26 male, 24 female; age range, 18-45 years) with PFPS underwent a standardized history and physical examination. After the evaluation, each subject performed 3 typically pain-producing functional activities (squatting, stepping up a 20-cm step, and stepping down a 20-cm step). The pain level perceived during each activity was rated on a numerical pain scale (0 representing no pain and 10 the worst possible pain). Following the assessment, all subjects were treated with a lumbopelvic manipulation, which was immediately followed by retesting the 3 functional activities to determine if there was any change in pain ratings. An immediate overall 50% or greater reduction in pain, or moderate or greater improvement on a global rating of change questionnaire, was considered a treatment success. Likelihood ratios (LRs) were calculated to determine which examination items were most predictive of treatment outcome.

RESULTS

Data for 49 subjects were included in the data analysis, of which 22 (45%) had a successful outcome. Five predictor variables were identified. The most powerful predictor of treatment success was a side-to-side difference in hip internal rotation range of motion greater than 14 masculine (+LR, 4.9). If this variable was present, the chance of experiencing a successful outcome improved from 45% to 80%.

CONCLUSION

A CPR was developed to predict an immediate successful response to lumbopelvic manipulation in patients with PFPS. However, in light of a limited sample size and omission of potentially meaningful predictor variables, future studies are necessary to validate the CPR.

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.

Role of the vastus medialis obliquus in repositioning the patella: a dynamic computed tomography study

BACKGROUND

It has been assumed that patellofemoral pain syndrome results from patellar malalignment. The precise role the vastus medialis obliquus plays in mediating the underlying pathologic abnormality is unclear.

HYPOTHESIS

The morphologic characteristics of the vastus medialis obliquus correlate to patellar malalignment in patients with patellofemoral pain syndrome.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

One hundred twelve patients with patellofemoral pain syndrome were studied. Six sets of computed tomography axial images were assessed in which knee flexion was 0 degrees, 15 degrees, or 30 degrees and the quadriceps muscle either relaxed or contracted. Measurements of serial cross-sectional areas of the vastus medialis obliquus and patellar malalignment were made. Correlation and stepwise regression models between the vastus medialis obliquus variables and patellar malalignment (lateral shift and patellar tilt) were calculated. Statistics were calculated on 4 subgroups depending on patellofemoral malalignment type.

RESULTS

Significant correlations were found between measures of cross-sectional areas of vastus medialis obliquus and patellar tilt at 0 degrees and 30 degrees of knee flexion. Using a regression model, it was determined that vastus medialis obliquus is predictive of patellar tilt (R(2) = 0.078-0.130). This explanation was most apparent in the subgroup of patients with extreme patellar tilt and lateral shift malalignments (R(2) up to 0.824).

CONCLUSION

There are significant correlations between vastus medialis obliquus variables and patellar malalignments in extended knees of patients with patellofemoral pain syndrome.

CLINICAL RELEVANCE

Vastus medialis obliquus muscle function is important to consider in the rehabilitation of patients with patellofemoral pain syndrome, especially those with extreme patellar tilt and lateral shift malalignments.

Association between sonographic morphology of vastus medialis obliquus and patellar alignment in patients with patellofemoral pain syndrome

STUDY DESIGN

Descriptive, correlational, anatomical laboratory study.

OBJECTIVES

To investigate the association between the morphology of the vastus medialis obliquus (VMO) and patellar alignment in patients with patellofemoral pain syndrome (PFPS).

BACKGROUND

It has long been presumed that PFPS results from patellar malalignment. Strengthening of the VMO has been suggested as an intervention to treat individuals with PFPS, through correction of abnormal patellar tracking. However, the exact role of the VMO in the etiology and treatment of PFPS is not clear.

METHODS AND MEASURES

This study included 58 patients with PFPS, of which 31 had bilateral involvement. A total of 89 knees were imaged with a Merchant's view radiograph at 45 degrees of knee flexion to measure patellar alignment consisting of patellar tilt and congruence angles. Those 89 knees were also examined with sonography with the knee in full extension and quadriceps relaxed to measure VMO morphology and additional characteristics such as insertion level, insertion ratio, fiber angle, and volume. The level of association between radiographic and sonographic measurements was explored to determine any relationship between patellar alignment and morphology of the VMO.

RESULTS

The patellar tilt angle was negatively correlated with the VMO insertion level (r = -.58, P<.05), insertion ratio (r= -.52, P<.05), and volume (r = -.45, P<.05). In addition, the patellar congruence angle was negatively correlated with the VMO fibers angle (r = -.23, P<.05).

CONCLUSIONS

This study showed that some aspects of VMO morphology, measured in full knee extension with the quadriceps relaxed, were associated with patellar alignment measured with the knee at 45 degrees of flexion. Whether or not VMO morphology serves as a predictor of patella alignment with the knee extended should be the focus of future investigations.

Diagnosis and management of a patient with knee pain using the movement system impairment classification system

STUDY DESIGN

Case report.

BACKGROUND

Selecting the most effective conservative treatment for knee pain continues to be a challenge. An understanding of the underlying movement system impairment that is thought to contribute to the knee pain may assist in determining the most effective treatment. Our case report describes the treatment and outcomes of a patient with the proposed movement system impairment (MSI) diagnosis of tibiofemoral rotation.

CASE DESCRIPTION

The patient was a 50-year-old female with a 3-month history of left anteromedial knee pain. Her knee pain was aggravated with sitting, standing, and descending stairs. A standardized clinical examination was performed and the MSI diagnosis of tibiofemoral rotation was determined. The patient consistently reported an increase in pain with activities that produced abnormal motions or alignments of the lower extremity in the frontal and transverse planes. The patient was educated to modify symptom-provoking functional activities by restricting the abnormal motions and alignments of the lower extremity. Exercises were prescribed to address impairments of muscle length, muscle strength, and motor control proposed to contribute to the tibiofemoral rotation. Tape also was applied to the knee in an attempt to restrict tibiofemoral rotation.

OUTCOMES

The patient reported a cessation of pain and an improvement in her functional activities that occurred with correction of her knee alignment and movement pattern. Pain intensity was 2/10 at 1 week. At 10 weeks, pain intensity was 0/10 and the patient reported no limitations in sitting, standing, or descending stairs. The patient's score on the activities of daily living scale increased from 73% at the initial visit to 86% at 10 weeks and 96% at 1 year after therapy was discontinued.

DISCUSSION

This case report presented a patient with knee pain and an MSI diagnosis of tibiofemoral rotation. Diagnosis-specific treatment resulted in a cessation of the patient's pain and an improved ability to perform functional activities.

Differences in lower extremity anatomical and postural characteristics in males and females between maturation groups

STUDY DESIGN

Descriptive, cross-sectional.

OBJECTIVES

We compared lower extremity anatomical characteristics in males and females between different maturation groups.

BACKGROUND

Sex differences have been observed in lower extremity anatomical characteristics. While the reasons contributing to these sex differences in adults are unknown, there is evidence that anatomy and posture change considerably during growth and development.

METHODS AND MEASURES

One hundred seventy-three young athletes (age range, 9-18 years) were assessed for stage of maturation and placed into 1 of 3 groups, according to Tanners stages 1 and 2 (MatGrp1), 3 and 4 (MatGrp2), and 5 (MatGrp3). Participants were measured for pelvic angle, hip anteversion, quadriceps angle, tibiofemoral angle, femur length, tibial length, genu recurvatum, tibial torsion, navicular drop, general joint laxity, and anterior knee laxity. Data were compared by sex and maturation group.

RESULTS

When comparing maturation groups, limb length, pelvic angle, and tibial torsion increased with maturation, and anterior knee laxity, genu recurvatum, tibiofemoral angle, and foot pronation decreased with maturation. Females had greater general joint laxity, hip anteversion, and tibiofemoral angles, and shorter femur and tibial lengths than males, regardless of maturation group. Maturational changes in knee laxity and quadriceps angles were sex dependent.

CONCLUSIONS

We observed a general change of posture with maturation that began with greater knee valgus, knee recurvatum, and foot pronation in MatGrp1, then moved toward a relative straightening and external rotation of the knee, and supination of the foot in later maturation groups. While the majority of the measures changed similarly in males and females across maturation groups, decreases in quadriceps angles and anterior knee laxity were greater in males compared to females, and females were observed to have a more inwardly rotated hip and valgus knee posture, compared to males, particularly in later maturation groups.

Different effects of femoral and tibial rotation on the different measurements of patella tilting: An axial computed tomography study

BACKGROUND

The various measurements of patellar tilting failed to isolate patellar tilting from the confounding effect of its neighboring bone rotation (femoral and tibial rotation) in people sustaining patellofemoral pain (PFPS). Abnormal motions of the tibia and the femur are believed to have an effect on patellofemoral mechanics and therefore PFPS. The current work is to explore the various effects of neighboring bone rotation on the various measurements of patellar tilting, through an axial computed tomography study, to help selecting a better parameter for patella tilting and implement a rationale for the necessary intervention at controlling the limb alignment in the therapeutic regime of PFPS.

METHODS

Forty seven patients (90 knees), comprising of 34 females and 11 males, participated in this study. Forty five knees, from randomly selected sides of bilaterally painful knees and the painful knees of unilaterally painful knees, were enrolled into the study. From the axial CT images in the subject knees in extension with quadriceps relaxed, the measurements of femoral rotation, tibial rotation, femoral rotation relative to tibia, and 3 parameters for patella tilting were obtained and analyzed to explore the relationship between the different measurements of patella tilt angle and the measurements of its neighboring bone rotation (femoral, tibial rotation, and femoral rotation relative to tibia).

RESULTS

The effect of femoral, tibial rotation, and femoral rotation relative to tibia on patella tilting varied with the difference in the way of measuring the patella tilt angle. Patella tilt angle of Grelsamer increased with increase in femoral rotation, and tibial rotation. Patella tilt angle of Sasaki was stationary with change in femoral rotation, tibial rotation, or femoral rotation relative to tibia. While, modified patella tilt angle of Fulkerson decreased with increase in femoral rotation, tibial rotation, or femoral rotation relative to tibia.

CONCLUSION

The current study has demonstrated various effects of regional bony alignment on the different measurements of the patellar tilt. And the influence of bony malalignment on the patellar tilt might draw a clinical implication that patellar malalignment can not be treated, separately, independent of the related limb alignment. This clinical implication has to be verified by further works, with a comprehensive evaluation of the various treatments of patellar malalignment.

Lower extremity mechanics of females with and without patellofemoral pain across activities with progressively greater task demands

BACKGROUND

Patellofemoral pain is commonly associated with lower extremity joint rotations that decrease retropatellar contact area and subsequently increase retropatellar stress during weightbearing activities. People with patellofemoral pain are thought to be capable of avoiding such harmful mechanics during activities with low external demands. However, this may not be possible during more demanding activities. The purpose of this study was to analyze lower extremity mechanics in females with and without patellofemoral pain during three different activities. Specifically, we sought to determine if differences between groups increase with increasingly demanding activities.

METHODS

20 females with patellofemoral pain and 20 healthy female controls performed single leg squats, running, and repetitive single leg jumps as their three-dimensional lower extremity mechanics were recorded. Transverse and frontal plane hip and knee kinematics were compared between groups for all activities.

FINDINGS

Differences in the variables of interest between groups did not generally depend on the nature of the activity. The patellofemoral pain group performed all three activities with 4.3 degrees greater knee external rotation (P=0.06), 3.5 degrees greater hip adduction (P=0.012), and 3.9 degrees decreased hip internal rotation with respect to the control group (P=0.01).

INTERPRETATION

These results suggest that females with patellofemoral pain do not employ different mechanics as demand of the activity increases. Rather, females with patellofemoral pain seem to demonstrate similar abnormal lower extremity mechanics across a variety of activities.

Hip strength and hip and knee kinematics during stair descent in females with and without patellofemoral pain syndrome

STUDY DESIGN

Cross-sectional.

OBJECTIVE

To determine if females presenting with patellofemoral pain syndrome (PFPS) from no discernable cause other than overuse demonstrate hip weakness and increased hip internal rotation, hip adduction, and knee valgus during stair descent.

BACKGROUND

Historically, PFPS has been viewed exclusively as a knee problem. Recent findings have indicated an association between hip weakness and PFPS. Researchers have hypothesized that patients who demonstrate hip weakness would exhibit increased hip internal rotation, hip adduction, and knee valgus during functional activities. To date, researchers have not simultaneously examined hip and knee strength and kinematics in subjects with PFPS to make this determination.

METHODS AND MEASURES

Eighteen females diagnosed with PFPS and 18 matched controls participated. Strength measures were taken for the hip external rotators and hip abductors. Hip and knee kinematics were collected as subjects completed a standardized stair-stepping task. Independent t tests were used to determine between-group differences in strength and kinematics during stair descent.

RESULTS

Subjects with PFPS generated 24% less hip external rotator (P = .002) and 26% less hip abductor (P =. 006) torque. No between-group differences (P > .05) were found for average hip and knee transverse and frontal plane angles during stair descent.

CONCLUSION

Subjects with PFPS had significant hip weakness but did not demonstrate altered hip and knee kinematics as previously theorized. Additional investigations are needed to better understand the association between hip weakness and PFPS etiology.

Quadriceps angle and risk of injury among high school cross-country runners

DESIGN

Prospective cohort study.

OBJECTIVES

To determine the relationship between quadriceps angle (Q-angle) and risk of lower extremity injury among adolescent cross-country runners.

BACKGROUND

No consensus exists on the role of the Q-angle as a risk factor for lower-extremity overuse injury, especially the effect of large Q-angle or right-left Q-angle difference.

METHODS AND MEASURES

The Q-angles of 393 high school cross-country runners, 13 to 19 years of age, were goniometrically measured in a static, standing position with quadriceps relaxed. The runners were followed during a cross-country season to assess lower extremity injuries resulting from running in practices or competitions.

RESULTS

Runners with a Q-angle >20 degrees were at 1.7 times greater risk of injury (relative risk [RR], 1.7; 95% confidence interval [CI]: 1.2, 2.4) compared with runners whose Q-angle was 10 degrees to <15 degrees . The RR estimates were similar among girls and boys. Runners with >4 degrees absolute right-left Q-angle difference were at 1.8 times greater risk (RR, 1.8; 95% CI: 1.4, 2.5) compared to runners with a smaller difference. Runners with a Q-angle >20 degrees were more likely to injure their knee, while runners with >4 degrees Q-angle difference were more likely to injure their shin. Runners with a Q-angle >20 degrees had greater time lost due to injury.

CONCLUSIONS

High school cross-country runners with large or asymmetric Q-angles may be at greater risk for running injury. Our study suggests that Q-angle measurement be included in preseason screening exams.

Effect of foot deformity on conventional mechanical axis deviation and ground mechanical axis deviation during single leg stance and two leg stance in genu varum

We assessed the effect of foot deformity on the loading axis of lower limbs in 33 patients with genu varum (25 bilateral and eigth unilateral) caused by varying etiologies including achondroplasia, cerebral palsy, prior trauma, rickets, metaphyseal chondrodysplasia and primary osteoarthritis using single leg stance and both leg stance radiographs. Deviation at the knee from the hip ankle line (conventional) and hip foot line (centre of hip to centre of heel) was calculated. A comparison was made between single leg stance and two leg stance for tibiocalcaneal angle, mechanical axis angle, knee and ankle joint line convergence angle, conventional mechanical axis deviation (MADC) and ground mechanical axis deviation (MADG). In addition comparisons were also made among three groups formed depending on the tibiocalcaneal angle and MADC-MADG difference for all the above measurements. Mechanical axis deviation (calculated using the two methods) varied with the talocalcaneal angle and single leg stance. Patients with a fixed subtalar varus and with severe genu varum, where the normal compensatory subtalar eversion could not compensate showed that conventional mechanical axis deviation was significantly higher by 3.4+/-2.4 mm and ground mechanical axis deviation degrees was significantly higher by 3.8+/-3.2 mm in single leg stance when compared to two leg stance (p<.0001). Foot deformity should be included during preoperative evaluation and planning for knee deformity correction.

A prospective study on gait-related intrinsic risk factors for patellofemoral pain

OBJECTIVE

To prospectively determine gait-related risk factors for patellofemoral pain.

DESIGN

A prospective cohort study.

SETTING

Male and female recruits of the Belgian Royal Military Academy during a 6-week basic military training period.

PARTICIPANTS

Eighty-four officer cadets (65 men, 19 women), who entered the Military Academy and were without a history of any knee or lower-leg complaints, participated in the study.

INTERVENTIONS

Before the start of the 6-week basic military training period, plantar pressure measurements during walking were performed. During the basic military training period, patellofemoral complaints were diagnosed and registered by a sports medicine physician.

MAIN OUTCOME MEASUREMENTS

Plantar pressure measurements during walking were performed using a footscan pressure plate (RsScan International).

RESULTS

During the 6-week training period, 36 subjects developed patellofemoral pain (25 male and 11 female). Logistic regression analysis revealed that subjects who developed patellofemoral pain had a significantly more laterally directed pressure distribution at initial contact of the foot, a significantly shorter time to maximal pressure on the fourth metatarsal, and a significantly slower maximal velocity of the change in lateromedial direction of the center of pressure during the forefoot contact phase.

CONCLUSIONS

Our findings suggest that the feet of the persons who developed anterior knee pain have a heel strike in a less pronated position and roll over more on the lateral side compared with the control group. The results of this study can be considered valuable in identifying persons at risk for patellofemoral pain.

Patellofemoral joint contact area is influenced by tibiofemoral rotation alignment in individuals who have patellofemoral pain

STUDY DESIGN

Observational, cohort study.

OBJECTIVES

To test the hypothesis that patellar alignment and tibiofemoral rotation alignment explain unique portions of variance in patellofemoral joint contact area in individuals with patellofemoral pain (PFP) and in pain-free control subjects.

BACKGROUND

PFP has been proposed to result from increased patellofemoral joint stress due to decreased contact area. Patellar malalignment (lateral displacement and tilt) is believed to be the main contributor to decreased contact area. Recent studies suggest that transverse plane rotation of the femur and/or tibia may also contribute to decreased contact area.

METHODS AND MEASURES

Twenty-one subjects with PFP (16 female, 5 male) and 21 pain-free subjects (14 female, 7 male) participated. Subjects underwent magnetic resonance imaging with the knee in full extension and the quadriceps contracted. Measures of patellofemoral joint contact area, lateral patellar displacement, patellar tilt angle, tibiofemoral rotation angle, and patellar width were obtained. Hierarchical multiple regression analyses were performed for each group using contact area as the dependent variable. The order of independent variables was patellar width, patellar tilt angle, and tibiofemoral rotation angle. To avoid multicolinearity, lateral patellar displacement was not included.

RESULTS

In the PFP group, patellar width and tibiofemoral rotation angle explained 46% of the variance in contact area. In pain-free subjects, patellar width was the only predictor of contact area, explaining 31% of its variance. Patellar tilt angle did not predict contact area in either group.

CONCLUSION

Addressing factors that control tibiofemoral rotation may be indicated to increase contact area and reduce pain in individuals with PFP. Future studies should investigate the contributions of patellar alignment and tibiofemoral rotation to patellofemoral joint contact area at a variety of knee flexion angles.

Patellofemoral Pain

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

Hip Strength in Collegiate Female Athletes with Patellofemoral Pain

PURPOSE

Decreased hip strength has been theorized to contribute to the development of patellofemoral pain. The purpose of this study was to test for strength differences of six hip muscle groups in collegiate female athletes diagnosed with unilateral patellofemoral pain compared with the unaffected leg and noninjured sport-matched controls.

METHODS

At four Division III schools, all collegiate female athletes experiencing unilateral patellofemoral pain were recruited during the 2004-2005 academic school year. The athletes were diagnosed with patellofemoral pain by sports medicine-trained family physicians or orthopedic surgeons. Hip strength of six different muscle groups was tested using a handheld dynamometer. The highest value of two trials was used, and strength values were normalized to body weight. The measurements from the injured leg were compared with the uninvolved leg and also with uninjured control subjects matched for sport.

RESULTS

Thirteen athletes were diagnosed with unilateral patellofemoral pain. The injured-side hip abductor (P = 0.003) and external rotator muscle groups (P = 0.049) were significantly weaker than the noninjured sides. There were no significant differences in the other hip muscles tested. In addition, the injured legs were significantly weaker in five of the six hip muscle groups compared with the control group.

CONCLUSIONS

The results of this study show that hip abductors and external rotators were significantly weaker between the injured and unaffected legs of the injured athletes. In addition, injured collegiate female athletes exhibited global hip weakness compared with age- and sport-matched asymptomatic controls. Screening for hip muscle weakness and adding strengthening exercises to the affected hip muscles may be important factors in managing female athletes with patellofemoral pain.

Sex differences in clinical measures of lower extremity alignment

STUDY DESIGN

Descriptive, cohort design.

OBJECTIVES

To comprehensively examine sex differences in clinical measures of static lower extremity alignment (LEA).

BACKGROUND

Sex differences in LEA have been included among a myriad of risk factors as a potential cause for the increased prevalence of knee injury in females. While clinical observations suggest that sex differences in LEA exist, little empirical data are available to support these sex differences or the normal values that should be expected in a healthy population.

METHODS AND MEASURES

The right and left static LEA of 100 healthy college-age participants (50 males [mean +/- SD age, 23.3 +/- 3.6 years; height, 177.8 +/- 8.0 cm, body mass, 80.4 +/- 11.6 kg] and 50 females [mean +/- SD age, 21.8 +/- 2.5 years; height, 164.3 +/- 6.9 cm; body mass, 67.4 +/- 15.2 kg]) was measured. Each alignment characteristic was analyzed via separate repeated-measures analyses of variance, with 1 between-subject factor (sex) and 1 within-subject factor (side).

RESULTS

There were no significant sex-by-side interactions and no differences between sides. Females had greater mean anterior pelvic tilt, hip anteversion, quadriceps angles, tibiofemoral angles, and genu recurvatum than males (P < .0001). No sex differences were observed in tibial torsion (P = .131), navicular drop (P = .130), and rearfoot angle (P = .590).

CONCLUSION

Sex differences in LEA indicate that females, on average, have greater anterior pelvic tilt, thigh internal rotation, knee valgus, and genu recurvatum. These sex differences were not accompanied by differences in the lower leg, ankle, and foot. Understanding these collective sex differences in LEA may help us to better examine the influence of LEA on dynamic lower extremity function and clarify their role as a potential injury risk factor.

Biomechanical differences between unilateral and bilateral landings from a jump: gender differences

OBJECTIVE

To determine the effect of landing type (unilateral vs. bilateral) and gender on the biomechanics of drop landings in recreational athletes.

DESIGN

This study used a repeated measures design to compare bilateral and unilateral landings in male and female athletes. A repeated measures multivariate analysis of variance (type of landing*gender) was performed on select variables.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Sixteen female and 16 male recreational athletes.

MAIN OUTCOME MEASURES

Kinetic, kinematic, and electromyographic (EMG) data were collected on participants while performing bilateral and unilateral landings from a 40-cm platform.

RESULTS

Compared to bilateral landings, subjects performed unilateral landings with increased knee valgus, decreased knee flexion at initial contact, decreased peak knee flexion, decreased relative hip adduction, and increased normalized EMG of the rectus femoris, medial hamstrings, lateral hamstrings, and medial gastrocnemius (P < 0.005). During both types of landing, females landed with increased knee valgus and normalized vertical ground reaction force (VGRF) compared to males (P < 0.009), however, the interaction of landing type*gender was not significant (P = 0.29).

CONCLUSIONS

Compared to bilateral landings, male and female recreational athletes performed unilateral landings with significant differences in knee kinematic and EMG variables. Female athletes landed with increased knee valgus and VGRF compared to males during both types of landing.

Influence of step height on quadriceps onset timing and activation during stair ascent in individuals with patellofemoral pain syndrome

STUDY DESIGN

A case control study, with single observation.

OBJECTIVES

To compare the onset timing and activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) between subjects with and without patellofemoral pain syndrome (PFPS) at various step heights.

BACKGROUND

It has been theorized that delayed or reduced VMO activity relative to the VL contributes to lateral patellar tracking and PFPS. However, conflicting evidence exists in the literature regarding this proposed mechanism. The lack of agreement among studies may be attributed to inconsistent knee flexion angles used in previous studies.

METHODS AND MEASURES

Twenty subjects with PFPS (mean +/- SD age, 29.5 +/- 10 years) and 20 control subjects (mean +/- SD age, 25.4 +/- 3.1 years) ascended 5 different step heights, while knee kinematics and quadriceps EMG data were collected. Knee flexion angle at foot-step contact, VMO-VL onset timing, and VMO/VL activation ratios were analyzed between groups and step heights using 2-factor analyses of variance (ANOVAs) with repeated measures (alpha = .05).

RESULTS

Individuals with PFPS demonstrated 4.7 degrees (P = .038) more knee flexion at foot-step contact than control subjects. Despite greater knee flexion with increased step height (P<.001), no differences in onset timing or activation magnitude ratio were present between groups or across step heights. However, individuals with PFPS displayed a significantly increased activation duration ratio compared to the control group (P = .043).

CONCLUSION

Quadriceps onset timing and activation magnitude during stair ascent was similar between individuals with and without PFPS, regardless of step height. Thus, the results of this study are in agreement with evidence indicating no difference in VMO-VL timing and VMO/VL activation magnitude ratio between individuals with and without PFPS.

Differences in lower extremity kinematics between a bilateral drop-vertical jump and a single-leg step-down

STUDY DESIGN

Mixed-model, repeated-measures design in a laboratory setting.

OBJECTIVES

To examine the differences in hip, knee, and ankle kinematics between a bilateral drop-vertical jump and single-leg step-down. A secondary purpose was to examine gender differences in kinematics of the tasks.

BACKGROUND

Both a drop-vertical jump and step-down task have been used to evaluate lower extremity movement and injury risk. The differences in joint angles between these tasks have not been reported.

METHODS AND MEASURES

Three-dimensional joint angles of the hip, knee, and ankle of 19 females and 18 males were evaluated with a high-speed camera system while the subjects performed a bilateral drop-vertical jump and a single-leg step-down. Maximum joint angles were compared between tasks and genders using ANOVA models. eversion (12 degrees compared to 8 degrees) (P<.0005) and hip adduction (16 degrees compared to 1 degrees) (P= .03) than the drop-vertical jump. Females had greater hip internal rotation in the step-down than in the drop-vertical jump (5 degrees compared to 2 degrees) (P = .02). When averaged across both tasks, females had greater knee abduction than males in both tasks (4 degrees compared to 0 degrees) (P<.0005).

CONCLUSIONS

The unilateral step-down task produced greater motion in the frontal and transverse planes at the ankle and hip, and would be appropriate in evaluating control of the hip. The bilateral drop-vertical jump produced greater knee abduction in both genders and may be appropriate for evaluating excessive knee abduction as a risk factor for noncontact anterior cruciate ligament injury, for example. The 2 tasks appear to challenge the neuromuscular system in different manners, and both should continue to be used in the investigation of injury risk.

Analysis of hip strength in females seeking physical therapy treatment for unilateral patellofemoral pain syndrome

STUDY DESIGN

Cross-sectional.

OBJECTIVES

To investigate whether females seeking physical therapy treatment for unilateral patellofemoral pain syndrome (PFPS) exhibit deficiencies in hip strength compared to a control group.

BACKGROUND

Decreased hip strength may be associated with poor control of lower extremity motion during weight-bearing activities, leading to abnormal patellofemoral motions and pain. Previous studies exploring the presence of hip strength impairments in subjects with PFPS have reported conflicting results.

METHODS AND MEASURES

Twenty females, aged 12 to 35 years, participated in the study. Ten subjects with unilateral PFPS were compared to 10 control subjects with no known knee pathologies. Hip abduction, extension, and external rotation strength were tested using a handheld dynamometer. A limb symmetry index (LSI) was used to quantify physical performance for all tests.

RESULTS

The symptomatic limbs of subjects with PFPS exhibited impairments in hip strength for all variables tested. LSI values in subjects with PFPS (range, 71%-79%) were significantly lower than those in control subjects (range, 93%-101%) (P< or =.007). A secondary analysis of data normalized to body mass demonstrated that the symptomatic limbs of subjects with PFPS had 52% less hip extension strength (P<.001), 27% less hip abduction strength (P = .007), and 30% less hip external rotation strength (P= .004) when compared to the weaker limbs of control subjects.

CONCLUSION

Females aged 12 to 35 presenting with unilateral PFPS demonstrate significant impairments in hip strength compared to control subjects when LSI values or body mass normalized values are used to quantify physical performance of the symptomatic limb.

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.

Rear-foot, mid-foot and fore-foot motion during the stance phase of gait

This paper proposes a new protocol designed to track a large number of foot segments during the stance phase of gait with the smallest possible number of markers, with particular clinical focus on coronal plane alignment of the rear-foot, transverse and sagittal plane alignment of the metatarsal bones, and changes at the medial longitudinal arch. The shank, calcaneus, mid-foot and metatarsus were assumed to be 3D rigid bodies. The longitudinal axis of the first, second and fifth metatarsal bones and the proximal phalanx of the hallux were also tracked independently. Skin markers were mounted on bony prominences or joint lines, avoiding the course of main tendons. Trajectories of the 14 markers were collected by an eight-camera motion capture system at 100 Hz on a population of 10 young volunteers. Three-dimensional joint rotations and planar angles were calculated according to anatomically based reference frames. The marker set was well visible throughout the stance phase of gait, even in a camera configuration typical of gait analysis of the full body. The time-histories of the joint rotations and planar angles were well repeatable among subjects and consistent with clinical and biomechanical knowledge. Several dynamic measurements were originally taken, such as elevation/drop of the medial longitudinal arch and of three metatarsal bones, rear-foot to fore-foot rotation and transverse plane deformation of the metatarsus. The information obtained from this protocol, consistent with previous clinical knowledge, enhanced our understanding of the dynamics of the human foot during stance.

Immediate Effect of Grade IV Inferior Hip Joint Mobilization on Hip Abductor Torque: A Pilot Study

Joint mobilization and manipulation stimulate mechanoreceptors, which may influence the joint and surrounding muscles. The purpose of this pilot study was to determine the effect of grade IV inferior hip joint mobilization on hip abductor torque. Thirty healthy subjects were randomly assigned to a control group (grade I inferior hip joint mobilization) or an experimental group (grade IV inferior hip joint mobilization). Subjects performed a pre- and post-intervention test of five isometric repetitions on the Cybex Normö dynamometer; the average torque was determined for both pre- and post-intervention measurements. These data were analyzed using the independent samples t-test with the significance level set at P<0.05. The results showed a statistically significant difference between the two groups for an increase in hip abductor torque in the experimental group (P=0.03). The experimental group demonstrated a 17.35% increase in average torque whereas the control group demonstrated a 3.68% decrease in average torque. These findings are consistent with other studies demonstrating that the use of grade IV non-thrust mobilization improves strength immediately post-intervention in healthy individuals. The results of this pilot study provide physical therapists with further support for the utilization of manual therapy in conjunction with therapeutic exercise to enhance muscle strength.

Tibia and rearfoot motion and ground reaction forces in subjects with patellofemoral pain syndrome during walking

Abnormal subtalar joint function and the consequent rotation of the tibia during walking are thought to contribute to patellofemoral pain syndrome (PFPS). The purpose of this study was to measure rearfoot and tibia motion, and the ground reaction force (GRF) during the stance phase of walking in subjects with PFPS and compare them to healthy subjects. A four camera motion analysis system with a single force plate was used to investigate rearfoot motion relative to the tibia in three planes, the tibial transverse plane rotation and the GRF during the stance phase of walking in 13 female subjects diagnosed with PFPS and 14 healthy females. Analysis showed significantly delayed peak rearfoot eversion (p=0.02), and earlier occurrence of peak dorsiflexion (p=0.02) for the PFPS group. Furthermore, significantly lower peak medial GRF (p=0.03), minimum vertical GRF trough (p=0.02) and the second vertical GRF peak (p=0.01) were found in the PFPS group. Tibial transverse rotation was not shown to be different in PFPS subjects. However, there was prolonged rearfoot eversion during the stance phase of walking. The earlier appearance of rearfoot dorsiflexion as well as the lower GRFs indicate altered propulsive function of the foot during supination.

Outcomes of a Weight-Bearing Rehabilitation Program for Patients Diagnosed With Patellofemoral Pain Syndrome

OBJECTIVE

To determine the effects of a weight-bearing rehabilitation program on quadriceps and gluteus medius electromyographic activity, pain, and function in subjects diagnosed with patellofemoral pain syndrome (PFPS).

DESIGN

Pretest and posttest 6-week intervention study.

SETTING

Musculoskeletal research laboratory.

PARTICIPANTS

Fourteen subjects diagnosed with PFPS and 14 healthy control subjects volunteered to participate in this study. No subjects withdrew from the study because of adverse effects.

INTERVENTION

Subjects diagnosed with PFPS participated in a 6-week rehabilitation program. The rehabilitation program consisted of weight-bearing exercises that focused on strengthening the quadriceps and hip abductor musculature.

MAIN OUTCOME MEASURES

Electromyographic onsets of the vastus medialis oblique (VMO) and vastus lateralis and onset and duration of the gluteus medius were collected during a stair-stepping task that was performed during the pretest and posttest. A visual analog scale (VAS) and Functional Index Questionnaire (FIQ) were administered at pretest and posttest and each week of the intervention.

RESULTS

Vastus lateralis and VMO onset timing differences (vastus lateralis electromyographic onset minus VMO electromyographic onset) and VAS and FIQ scores significantly improved for patients diagnosed with PFPS. Vastus lateralis and VMO onset timing in the PFPS group were significantly different from those in the control group at baseline and were not significantly different from the control group after the intervention. We did not find differences in gluteus medius onsets or duration of activity.

CONCLUSIONS

Subjects diagnosed with PFPS responded favorably and quickly to a therapeutic exercise program that incorporated quadriceps and hip musculature strengthening. The efficacy of the therapeutic exercise program used in this study should be further investigated in a larger subject population.

Influence of a custom foot orthotic intervention on lower extremity dynamics in healthy runners

OBJECTIVE

To investigate the influence of a custom foot orthotic intervention on the lower extremity dynamics in healthy runners.

DESIGN

Three-dimensional kinematics and kinetics were collected on 15 female runners (>15 miles per week) while each performed the over-ground running trials in either a shoe only or a shoe+custom foot orthotic condition. Kinematic and kinetic variables were analyzed using Paired Sample t-tests.

BACKGROUND

Custom foot orthotics are frequently prescribed treatment modality for the management of overuse running injuries. Although it is generally accepted that a custom foot orthotic intervention produces positive clinical outcomes, it remains unclear what influence this therapeutic modality has on the dynamics of the lower extremity.

METHODS

Each subject performed five acceptable over-ground running trials (3.6 m s(-1) +/-5%) with and without the custom foot orthotic intervention in a running shoe. Selected maximum ankle and knee joint angles and moments were measured during the stance phase.

RESULTS

While wearing the custom foot orthotic, subjects exhibited significantly decreased maximum values in rearfoot eversion angle, rearfoot eversion velocity and internal ankle inversion moment.

CONCLUSIONS

In this sample of healthy female runners, the custom foot orthotic intervention led to significant decreases in maximum values for ankle dynamics in the frontal plane and in the sagittal plane of the knee joint. Relevance It remains unclear how a custom foot orthotic intervention influences lower extremity dynamics to produce positive clinical outcomes. Furthering our understanding of the dynamic influence will not only inform improved prescription and manufacturing practices but may provide insight into the mechanisms that cause overuse injuries.

The influence of in-season injury prevention training on lower-extremity kinematics during landing in female soccer players

OBJECTIVE

To examine the influence of in-season injury prevention training on hip and knee kinematics during a landing task.

DESIGN

Longitudinal pre-post intervention study.

SETTING

Testing sessions were conducted in a biomechanics research laboratory.

PARTICIPANTS

Eighteen female soccer players between the ages of 14 and 17 participated in this study. All subjects were healthy with no current complaints of lower extremity injury.

INTERVENTIONS

Testing sessions were conducted prior to and following a season of soccer practice combined with injury prevention training.

MAIN OUTCOME MEASUREMENTS

During each testing session three-dimensional kinematics were collected while each subject performed a drop landing task. Peak hip and knee joint angles were measured during the early deceleration phase of landing and compared between pre- and post-training using paired t-tests.

RESULTS

Following a season of soccer practice combined with injury prevention training, females demonstrated significantly less hip internal rotation (7.1 degrees vs. 1.9 degrees; P = 0.01) and significantly greater hip abduction (-4.9 degrees vs. -7.7 degrees; P = 0.02). No differences in knee valgus or knee flexion angles were found post-season.

CONCLUSIONS

Female soccer players exhibited significant changes in hip kinematics during a landing task following in-season injury prevention training. Our results support the premise that a season of soccer practice combined with injury prevention training is effective in altering lower extremity motions that may play a role in predisposing females to ACL injury.

The role of hip muscle function in the treatment of patellofemoral pain syndrome

BACKGROUND

Previous literature has associated hip weakness with patellofemoral pain syndrome.

HYPOTHESIS

Improvements in hip strength and flexibility are associated with a decrease in patellofemoral pain.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Thirty-five patients with patellofemoral pain syndrome, aged 33 +mn; 16 years (29 women, 6 men; 43 knees), were evaluated and placed on a 6-week treatment program. Hip flexion, abduction, and adduction strengths, Thomas and Ober test results, and visual analog scale scores for pain with activities of daily living as well as with exercise were documented on initial evaluation and again 6 weeks later. Treatment consisted of strength and flexibility exercises primarily focusing on the hip.

RESULTS

Hip flexion strength improved by 35% +/- 8.4% in 26 lower extremities treated successfully, compared with -1.8% +/- 3.5% in 17 lower extremities with an unsuccessful outcome (P < .001). Before treatment, there were positive Ober test results in 39 of 43 lower extremities; positive Thomas test results were seen in 31 of 43 lower extremities. A successful outcome with a concurrent normalized Ober test result was seen in 83% (20/24) of lower extremities, and successful outcomes with normalized Thomas test results were seen in 80% (16/20) of lower extremities. A combination of improved hip flexion strength (> 20%) as well as normal Ober and Thomas test results was seen in 93% of successfully treated cases (14/15 lower extremities), compared with 0% success (0/5 lower extremities) if there was no change in hip flexion strength (< 20%) and if Ober and Thomas test results remained positive.

CONCLUSIONS

Improvements in hip flexion strength combined with increased iliotibial band and iliopsoas flexibility were associated with excellent results in patients with patellofemoral pain syndrome.

Physical Examination and Patellofemoral Pain Syndrome

Patellofemoral pain syndrome, which accounts for 25% of all sports-related knee injuries, is multifactorial in origin. A combination of variables, including abnormal lower limb biomechanics, soft-tissue tightness, muscle weakness, and excessive exercise, may result in increased cartilage and subchondral bone stress, patellofemoral pain, and subtle or more overt patellar maltracking. Because of the multiple forces affecting the patellofemoral joint, the clinical evaluation and treatment of this disorder is challenging. An extensive search of the literature revealed no single gold-standard test maneuver for that disorder, and the reliability of the maneuvers described was generally low or untested. An abnormal Q-angle, generalized ligamentous laxity, hypomobile or hypermobile tenderness of the lateral patellar retinaculum, patellar tilt or mediolateral displacement, decreased flexibility of the iliotibial band and quadriceps, and quadriceps, hip abductor, and external rotator weakness were most often correlated with patellofemoral pain syndrome.

Correlations between Hip Strength and Static Foot and Knee Posture

Context:

Hip-muscle weakness might be associated with impaired biomechanics and postures that contribute to lower extremity injuries.

Objective:

To examine relationships between hip-muscle strength, Q angle, and foot pronation.

Design:

Correlational study.

Setting:

Academic laboratory.

Participants:

33 healthy adults.

Main Outcome Measures:

Maximal isometric hip abduction (Abd), adduction (Add), external-rotation (ER) and internal-rotation (IR) strength; Q angle of the knee; and longitudinal arch angle of the foot. We analyzed Pearson product– moment (r) correlation coefficients between the Abd/Add and ER/IR force ratios, Q angle, and longitudinal arch angle.

Results:

The hip Abd/Add force ratio was correlated with longitudinal arch angle (r= .35,P= .025).

Conclusions:

Reduced strength of the hip abductors relative to adductors is associated with increased pronation at the foot. Clinicians should be aware of this relationship when examining patients with lower extremity impairments.

Strength around the hip and flexibility of soft tissues in individuals with and without patellofemoral pain syndrome

STUDY DESIGN

Case control design.

OBJECTIVES

To investigate whether differences exist in lower extremity muscle strength and soft tissue length between patients with patellofemoral pain syndrome (PFPS) and age- and gender-matched control subjects.

BACKGROUND

Based on our clinical experience and emerging data, impairments such as muscular weakness surrounding the hip and limited flexibility of key lower extremity muscles may be important impairments to consider in the conservative management of PFPS.

METHODS AND MEASURES

Thirty patients with PFPS and 30 age- and gender-matched controls without PFPS (17 females and 13 males in each group) participated in the study. Data were collected during 1 testing session by an examiner not blinded to group assignment. Demographic, health history, physical activity levels, and pain and function were assessed using patient-completed measures. Physical examination measures included assessment of hip external rotation strength, hip abduction strength, length of the iliotibial band/tensor fascia lata complex, gastrocnemius length, soleus length, and quadriceps and hamstrings muscles length.

RESULTS

Patients with PFPS demonstrated significantly less flexibility of the gastrocnemius, soleus, quadriceps, and hamstrings compared to healthy control subjects. No differences existed in flexibility of the iliotibial band/tensor fascia lata complex and strength of the hip external rotators and abductors. Multivariate stepwise discriminant analysis identified gastrocnemius length, hip abduction strength, and soleus length as being able to distinguish between patients with PFPS and healthy individuals without PFPS.

CONCLUSION

This study suggests that further research is warranted regarding the association of these impairments of muscle strength and soft tissue length in patients with PFPS.

Patellofemoral Pain and Asymmetrical Hip Rotation

Background and Purpose. Patellofemoral joint problems are the most common overuse injury of the lower extremity, and altered femoral or hip rotation may play a role in patellofemoral pain. The purpose of this case report is to describe the evaluation of and intervention for a patient with asymmetrical hip rotation and patellofemoral pain. Case Description. The patient was a 15-year-old girl with an 8-month history of anterior right knee pain, without known trauma or injury. Prior to intervention, her score on the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was 24%. Right hip medial (internal) rotation was less than left hip medial rotation, and manual muscle testing showed weakness of the right hip internal rotator and abductor muscles. The intervention was aimed at increasing right hip medial rotation, improving right hip muscle strength (eg, the muscle force exerted by a muscle or a group of muscles to overcome a resistance), and eliminating anterior right knee pain. Outcomes. After 6 visits (14 days), passive left and right hip medial rotations were symmetrical, and her right hip internal rotator and abductor muscle grades were Good plus. Her WOMAC score was 0%. Discussion. The patient had right patellofemoral pain and an uncommon pattern of asymmetrical hip rotation, with diminished hip medial rotation and excessive hip lateral (external) rotation on the right side. The patient's outcomes suggest that femoral or hip joint asymmetry may be related to patellofemoral joint pain.

Comprehensive functional evaluation of the injured runner

In most cases, a detailed history provides the information that is necessary for the clinician to diagnose the injured runner correctly; however, to treat the injury and guide a successful rehabilitation program, the physical examination must go beyond the standard regional musculoskeletal examination. The victims (tissue injury) and the culprits (biomechanical deficits) must be identified to facilitate treatment (Table 3). Gait and other dynamic assessments help to reveal underlying deficits in function that may have contributed to injury. In short, the entire functional kinetic chain must be considered and weak links identified.

Motor Unit Syncronization Is Reduced in Anterior Knee Pain

Anterior knee pain (AKP) is common and has been argued to be related to poor patellofemoral joint control due to impaired coordination of the vasti muscles. However, there are conflicting data. Changes in motor unit firing may provide more definitive evidence. Synchronization of motor unit action potentials (MUAPs) in vastus medialis obliquus (VMO) and vastus lateralis (VL) may contribute to coordination in patellofemoral joint control. We hypothesized that synchronization may be reduced in AKP. Recordings of single MUAPs were made from VMO and multiunit electromyograph (EMG) recordings were made from VL. Averages of VL EMG recordings were triggered from the single MUAPs in VMO. Motor units in VL firing in association with the VMO motor units would appear as a peak in the VL EMG average. Data were compared to previous normative data. The proportion of trials in which a peak was identified in the triggered averages of VL EMG was reduced in people with AKP (38%) compared to controls (90%). Notably, although 80% of subjects had values less than controls, 20% were within normal limits. These results provide new evidence that motor unit synchronization is modified in the presence of pain and provide evidence for motor control dysfunction in AKP.

PERSPECTIVE

This study shows that coordination of motor units between the medial and lateral vasti muscles in people with anterior knee pain is reduced compared to people without knee pain. It confirms that motor control dysfunction is a factor in this condition and has implications for selection of rehabilitation strategies.

Conservative management of subtle Lisfranc joint injury: a case report

STUDY DESIGN

Case report.

BACKGROUND

Athletic Lisfranc injuries are characterized by disruption of the soft tissues about the tarsometatarsal joint complex. They are frequently missed on initial consultation due to a paucity of demonstrable physical signs, yet often result in significant disability. This case illustrates the 2 great challenges in managing these injuries: firstly, arriving at an accurate diagnosis and, secondly determining whether the injury is stable and, therefore, appropriate for conservative management

CASE DESCRIPTION

The athlete was a 21-year-old professional basketball player with a recurrent ligamentous injury of the Lisfranc joint. A global approach to evaluation and treatment of the entire lower extremity and pelvis in managing this injury is emphasized.

OUTCOMES

The athlete in this case report made a successful return to his previous level of competition 12 weeks postinjury. At 2-year follow-up he continues to play professionally without any symptoms.

DISCUSSION

In selected cases for which patients have no osseous displacement and the ability to run on the toes soon after injury, conservative management of Lisfranc injury may be appropriate Key features of a conservative approach include recognition of a prolonged recovery time adequate rest for soft tissue healing, restoration of a normal gait pattern to prevent chronic overstress of injured tissues, appropriate orthotic prescription, and proprioceptive retraining.

The influence of altered lower-extremity kinematics on patellofemoral joint dysfunction: a theoretical perspective

Although patellofemoral pain (PFP) is recognized as being one of the most common disorders of the lower extremity, treatment guidelines and underlying rationales remain vague and controversial. The premise behind most treatment approaches is that PFP is the result of abnormal patellar tracking and/or patellar malalignment. Given as such, interventions typically focus on the joint itself and have traditionally included strengthening the vastus medialis oblique, taping, bracing, soft tissue mobilization, and patellar mobilization. More recently, it has been recognized that the patellofemoral joint and, therefore, PFP may be influenced by the interaction of the segments and joints of the lower extremity. In particular, abnormal motion of the tibia and femur in the transverse and frontal planes may have an effect on patellofemoral joint mechanics. With this in mind, interventions aimed at controlling hip and pelvic motion (proximal stability) and ankle/foot motion (distal stability) may be warranted and should be considered when treating persons with patellofemoral joint dysfunction. The purpose of this paper is to provide a biomechanical overview of how altered lower-extremity mechanics may influence the patellofemoral joint. By addressing these factors, better long-term treatment success and prevention may be achieved.