The influence of abnormal hip mechanics on knee injury: a biomechanical perspective

Anatomic anterior cruciate ligament reconstruction utilizing the double-bundle technique

The goal of every orthopaedic surgeon should be to restore anatomy as close as possible to normal. Intense research on reconstruction of the anterior cruciate ligament (ACL) and an advancing knowledge of the anatomy and function of the 2 primary bundles of the ACL have led to techniques of ACL reconstruction that more closely restore normal anatomy. Restoring the ACL footprint is one of the most important goals of the surgery, and the choice between anatomic single-bundle and double-bundle ACL reconstruction is determined by the anatomical features of each patient. After reconstruction, the graft undergoes a complex, lengthy process of remodeling; therefore, inappropriate (early), aggressive rehabilitation can lead to graft failure and compromise the patient's outcome. The purpose of this article is to provide an overview of the anatomy and function of the ACL, the methods for anatomic single-bundle and double-bundle ACL reconstruction, and our recommendations for postoperative rehabilitation.

Anterior cruciate ligament strain and tensile forces for weight-bearing and non-weight-bearing exercises: a guide to exercise selection

There is a growing body of evidence documenting loads applied to the anterior cruciate ligament (ACL) for weight-bearing and non-weight-bearing exercises. ACL loading has been quantified by inverse dynamics techniques that measure anterior shear force at the tibiofemoral joint (net force primarily restrained by the ACL), ACL strain (defined as change in ACL length with respect to original length and expressed as a percentage) measured directly in vivo, and ACL tensile force estimated through mathematical modeling and computer optimization techniques. A review of the biomechanical literature indicates the following: ACL loading is generally greater with non-weight-bearing compared to weight-bearing exercises; with both types of exercises, the ACL is loaded to a greater extent between 10° to 50° of knee flexion (generally peaking between 10° and 30°) compared to 50° to 100° of knee flexion; and loads on the ACL change according to exercise technique (such as trunk position). Squatting with excessive forward movement of the knees beyond the toes and with the heels off the ground tends to increase ACL loading. Squatting and lunging with a forward trunk tilt tend to decrease ACL loading, likely due to increased hamstrings activity. During seated knee extension, ACL force decreases when the resistance pad is positioned more proximal on the anterior aspect of the lower leg, away from the ankle. The evidence reviewed as part of this manuscript provides objective data by which to rank exercises based on loading applied to the ACL. The biggest challenge in exercise selection post-ACL reconstruction is the limited knowledge of the optimal amount of stress that should be applied to the ACL graft as it goes through its initial incorporation and eventual maturation process. Clinicians may utilize this review as a guide to exercise selection and rehabilitation progression for patients post-ACL reconstruction.

Recent advances in the rehabilitation of anterior cruciate ligament injuries

Rehabilitation following anterior cruciate ligament surgery continues to change, with the current emphasis being on immediate weight bearing and range of motion, and progressive muscular strengthening, proprioception, dynamic stability, and neuromuscular control drills. The rehabilitation program should be based on scientific and clinical research and focus on specific drills and exercises designed to return the patient to the desired functional goals. The goal is to return the patient's knee to homeostasis and the patient to his or her sport or activity as safely as possible. Unique rehabilitation techniques and special considerations for the female athlete will also be discussed. The purpose of this article is to provide the reader with a thorough scientific basis for anterior cruciate ligament rehabilitation based on graft selection, patient population, and concomitant injuries.

Current concepts for rehabilitation and return to sport after knee articular cartilage repair in the athlete

Articular cartilage injury is observed with increasing frequency in both elite and amateur athletes and results from the significant acute and chronic joint stress associated with impact sports. Left untreated, articular cartilage defects can lead to chronic joint degeneration and athletic and functional disability. Treatment of articular cartilage defects in the athletic population presents a therapeutic challenge due to the high mechanical demands of athletic activity. Several articular cartilage repair techniques have been shown to successfully restore articular cartilage surfaces and allow athletes to return to high-impact sports. Postoperative rehabilitation is a critical component of the treatment process for athletic articular cartilage injury and should take into consideration the biology of the cartilage repair technique, cartilage defect characteristics, and each athlete's sport-specific demands to optimize functional outcome. Systematic, stepwise rehabilitation with criteria-based progression is recommended for an individualized rehabilitation of each athlete not only to achieve initial return to sport at the preinjury level but also to continue sports participation and reduce risk for reinjury or joint degeneration under the high mechanical demands of athletic activity.

Risk factors for patellofemoral pain syndrome: a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

LEVEL OF EVIDENCE

Prognosis, level 1a-.

The effects of isolated hip abductor and external rotator muscle strengthening on pain, health status, and hip strength in females with patellofemoral pain: a randomized controlled trial

STUDY DESIGN

Randomized controlled trial.

OBJECTIVES

To examine the effectiveness of isolated hip abductor and external rotator strengthening on pain, health status, and hip strength in females with patellofemoral pain (PFP).

BACKGROUND

Altered hip kinematics resulting from hip muscle weakness has been proposed as a contributing factor in the development of PFP. To date, no study has examined clinical outcomes associated with isolated hip muscle strengthening in those with PFP.

METHODS

Twenty-eight females with PFP were sequentially assigned to an exercise (n = 14) or a no-exercise control group (n = 14). The exercise group completed bilateral hip abductor and external rotator strengthening 3 times per week for 8 weeks. Pain (visual analog scale), health status (WOMAC), and hip strength (handheld dynamometer) were assessed at baseline and postintervention. Pain and health status were also evaluated at 6 months postintervention in the exercise group. Two-factor mixed-model analyses of variance were used to determine the effects of the intervention on each outcome variable.

RESULTS

Significant group-by-time interactions were observed for each variable of interest. Post hoc testing revealed that pain, health status, and bilateral hip strength improved in the exercise group following the 8-week intervention but did not change in the control group. Improvements in pain and health status were sustained at 6-month follow-up in the exercise group.

CONCLUSION

A program of isolated hip abductor and external rotator strengthening was effective in improving pain and health status in females with PFP compared to a no-exercise control group. The incorporation of hip-strengthening exercises should be considered when designing a rehabilitation program for females with PFP.

LEVEL OF EVIDENCE

Therapy, level 2b.

Musculoskeletal myths

This paper discusses a number of common myths in the musculoskeletal pain management and rehabilitation/athletic development fields. The origins or rationale for these beliefs are reviewed. New scientific evidence disputing or refuting the myth is then presented followed by and explanation and evidence for an updated perspective.

Landing pattern modification to improve patellofemoral pain in runners: a case series

STUDY DESIGN

Case series.

BACKGROUND

Patellofemoral pain is a common overuse injury in runners. Recent findings suggest that patellofemoral pain is related to high-impact loading associated with a rearfoot strike pattern. This case series describes the potential training effects of a landing pattern modification program to manage patellofemoral pain in runners.

CASE DESCRIPTION

Three female runners with unilateral patellofemoral pain who initially presented with a rearfoot strike pattern underwent 8 sessions of landing pattern modification program using real-time audio feedback from a force sensor placed within the shoe. Ground reaction forces during running were assessed with an instrumented treadmill. Patellofemoral pain symptoms were assessed using 2 validated questionnaires. Finally, running performance was measured by self-reported best time to complete a 10-km run in the previous month. The runners were assessed before, immediately after, and 3 months following training.

OUTCOMES

The landing pattern of runners was successfully changed from a rearfoot to a nonrearfoot strike pattern after training. This new pattern was maintained 3 months after the program. The vertical impact peak and rates of loading were shown to be reduced. Likewise, the symptoms related to patellofemoral pain and associated functional limitations were improved. However, only 1 of the participants reported improved running performance after the training.

DISCUSSION

This case series provided preliminary data to support further investigation of interventions leading to landing pattern modification in runners with patellofemoral pain.

LEVEL OF EVIDENCE

Therapy, level 4.

Iliotibial band syndrome: soft tissue and biomechanical factors in evaluation and treatment

Muscle performance factors and altered loading mechanics have been linked to a variety of lower extremity musculoskeletal disorders. In this article, biomechanical risk factors associated with iliotibial band syndrome (ITBS) are described, and a strategy for incorporating these factors into the clinical evaluation of and treatment for that disorder is presented. Abnormal movement patterns in runners and cyclists with ITBS are discussed, and the pathophysiological characteristics of this syndrome are considered in light of prior and current studies in anatomy. Differential diagnoses and the use of imaging, medications, and injections in the treatment of ITBS are reviewed. The roles of hip muscle strength, kinematics, and kinetics are detailed, and the assessment and treatment of muscle performance factors are discussed, with emphasis on identifying and treating movement dysfunction. Various stages of rehabilitation, including strengthening progressions to reduce soft-tissue injury, are described in detail. ITBS is an extremely common orthopedic condition that presents with consistent dysfunctional patterns in muscle performance and movement deviation. Through careful assessment of lower quarter function, the clinician can properly identify individuals and initiate treatment.

Relationship between eccentric hip torque and lower-limb kinematics: gender differences

The purposes of this study were to compare lower-limb kinematics between genders, and determine the relationships among eccentric hip abductor and lateral rotator torques and lower-limb kinematics. The movements of the pelvis, femur, and knee were calculated for 16 women and 16 men during the single-leg squat. Eccentric hip abductor and lateral rotator torques were measured using an isokinetic dynamometer. The results showed that women had greater contralateral pelvic depression, femur adduction, and knee abduction than men. The eccentric hip abductor and lateral rotator torques were correlated with coronal plane femur and knee movements in the overall sample. When the genders were analyzed separately, it was observed that women with greater eccentric hip abductor torque exhibited less femur adduction and femur medial rotation, and greater knee adduction excursion. No significant relationship was observed between the isokinetic and kinematic variables in the male group. The differences between the genders help to explain the greater rate of knee disorders observed in women. Moreover, the eccentric hip abduction action seemed to be more important in women to control the lower-limb movements.

The effect of a hip-strengthening program on mechanics during running and during a single-leg squat

STUDY DESIGN

Block randomized controlled trial.

OBJECTIVES

To investigate whether a strengthening and movement education program, targeting the hip abductors and hip external rotators, alters hip mechanics during running and during a single-leg squat.

BACKGROUND

Abnormal movement patterns during running and single-leg squatting have been associated with a number of running-related injuries in females. Therapeutic interventions for these aberrant movement patterns typically include hip strengthening. While these strengthening programs have been shown to improve symptoms, it is unknown if the underlying mechanics during functional movements is altered.

METHODS

Twenty healthy females with excessive hip adduction during running, as determined by instrumented gait analysis, were recruited. The runners were matched by age and running distance, and randomized to either a training group or a control group. The training group completed a hip strengthening and movement education program 3 times per week for 6 weeks in addition to single-leg squat training with neuromuscular reeducation consisting of mirror and verbal feedback on proper mechanics. The control group did not receive an intervention but maintained the current running distance. Using a handheld dynamometer and standard motion capture procedures, hip strength and running and single-leg squat mechanics were compared before and after the strengthening and movement education program.

RESULTS

While hip abductor and external rotation strength increased significantly (P<.005) in the training group, there were no significant changes in hip or knee mechanics during running. However, during the single-leg squat, hip adduction, hip internal rotation, and contralateral pelvic drop all decreased significantly (P = .006, P = .006, and P = .02, respectively). The control group exhibited no changes in hip strength, nor in the single-leg squat or running mechanics at the conclusion of the 6-week study.

CONCLUSION

A training program that included hip strengthening and movement training specific to single-leg squatting did not alter running mechanics but did improve single-leg squat mechanics. These results suggest that hip strengthening and movement training, when not specific to running, do not alter abnormal running mechanics.

LEVEL OF EVIDENCE

Therapy, level 2b.

Physiotherapist agreement when visually rating movement quality during lower extremity functional screening tests

OBJECTIVES

To investigate physiotherapist agreement in rating movement quality during lower extremity functional tests using two visual rating methods and physiotherapists with differing clinical experience.

DESIGN

Clinical measurement.

PARTICIPANTS

Six healthy individuals were rated by 44 physiotherapists. These raters were in three groups (inexperienced, novice, experienced).

MAIN MEASURES

Video recordings of all six individuals performing four lower extremity functional tests were visually rated (dichotomous or ordinal scale) using two rating methods (overall or segment) on two occasions separated by 3-4 weeks. Intra and inter-rater agreement for physiotherapists was determined using overall percentage agreement (OPA) and the first order agreement coefficient (AC1).

RESULTS

Intra-rater agreement for overall and segment methods ranged from slight to almost perfect (OPA: 29-96%, AC1: 0.01 to 0.96). AC1 agreement was better in the experienced group (84-99% likelihood) and for dichotomous rating (97-100% likelihood). Inter-rater agreement ranged from fair to good (OPA: 45-79%; AC1: 0.22-0.71). AC1 agreement was not influenced by clinical experience but was again better using dichotomous rating.

CONCLUSIONS

Physiotherapists' visual rating of movement quality during lower extremity functional tests resulted in slight to almost perfect intra-rater agreement and fair to good inter-rater agreement. Agreement improved with increased level of clinical experience and use of dichotomous rating.

Hip muscle weakness in patients with symptomatic femoroacetabular impingement

OBJECTIVE

Femoroacetabular impingement (FAI) is a pathomechanical process, which may cause hip pain, disability and early development of hip osteoarthritis (OA) in young and active adults. Patients with FAI experience functional disability during dynamic weight-bearing activities, which could originate from weakness of the hip muscles. The objective of this study was to compare hip muscle strength between patients with symptomatic FAI and healthy controls. It was hypothesized that patients would present overall hip muscle weakness compared to controls.

METHODS

A total of 22 FAI patients and 22 controls matched for gender, age, and body mass participated in the study. We evaluated isometric maximal voluntary contraction (MVC) strength of all hip muscle groups using hand-held and isokinetic dynamometry, and electromyographic (EMG) activity of the rectus femoris (RF) and tensor fasciae latae (TFL) muscles during active flexion of the hip.

RESULTS

FAI patients had significantly lower MVC strength than controls for hip adduction (28%), flexion (26%), external rotation (18%) and abduction (11%). TFL EMG activity was significantly lower in FAI patients compared with controls (P=0.048), while RF EMG activity did not differ significantly between the two groups (P=0.056).

CONCLUSIONS

Patients with symptomatic FAI presented muscle weakness for all hip muscle groups, except for internal rotators and extensors. Based on EMG recordings, it was demonstrated that patients with symptomatic FAI have a reduced ability to activate TFL muscle during hip flexion. These findings provide orthopedic surgeons with objective information about the amount and specificity of hip muscle weakness in patients with FAI. Future research should investigate the relationship between hip muscle weakness, functional disability and overuse injury risks, as well as the effects of hip muscle strengthening on clinical outcomes in individuals with symptomatic FAI.

Successful rehabilitation of a recreational endurance runner: initial validation for the Bunkie test

This case report details the musculoskeletal evaluation and the successful rehabilitation of a 24-year-old female recreational distance runner who self-referred to physical therapy with an acute bout of low back pain (LBP). Her LBP was provoked during each distance run. The patient's musculoskeletal evaluation revealed core weakness, especially on the left. A recently reported functional test, the Bunkie test, was administered as part of the physical evaluation. The scores from the Bunkie test correlated with other quantitative and qualitative findings. A therapeutic exercise program emphasizing core stabilization was prescribed. The patient was able to shortly return to running pain-free.

Relationship among eccentric hip and knee torques, symptom severity and functional capacity in females with patellofemoral pain syndrome

OBJECTIVE

To determine the relationships between eccentric hip and knee torques, symptom severity and functional capacity in females with patellofemoral pain syndrome (PFPS).

DESIGN

Within-subject correlational study.

SETTING

University biomechanics laboratory.

PARTICIPANTS

10 females diagnosed with PFPS.

MAIN OUTCOME MEASURES

Eccentric strength of the hip abductors and lateral rotators, and knee extensors were assessed using an isokinetic dynamometer. A 10-cm visual analog scale was used to determine usual knee pain in the last week. The Anterior Knee Pain Scale (AKPS) was used to determine the functional capacity of the patients.

RESULTS

The study found that the greater the eccentric knee extensor and hip lateral rotator torques, the higher the functional capacity of the patients (p = 0.02, r = 0.72; p = 0.02, r = 0.72). It was also shown that the greater hip lateral rotator torque, the less the usual pain reported in the last week (p = 0.004, r = -0.84). Despite the lack of statistical significance (p = 0.11), it was also found a modest negative relationship between the eccentric knee extensor torque and the usual pain reported in the last week (r = -0.56) that was considered clinically meaningful (d = 1.4).

CONCLUSIONS

This study showed that eccentric knee extensor and hip lateral rotator torques were associated with functional capacity and pain level in females with PFPS. Further investigations should be carried out to verify the effects of an intervention program focused on the eccentric action of these muscles with respect to the symptoms in patients with PFPS.

Utilization of modified NFL combine testing to identify functional deficits in athletes following ACL reconstruction

STUDY DESIGN

Case control.

OBJECTIVES

To use modified NFL Combine testing methodology to test for functional deficits in athletes following anterior cruciate ligament (ACL) reconstruction following return to sport.

BACKGROUND

There is a need to develop objective, performance-based, on-field assessment methods designed to identify potential lower extremity performance deficits and related impairments in this population.

METHODS

Eighteen patients (mean ± SD age, 16.9 ± 2.1 years; height, 170.0 ± 8.7 cm; body mass, 71.9 ± 21.8 kg) who returned to their sport within a year following ACL reconstruction (95% CI: 7.8 to 11.9 months from surgery) participated (ACLR group). These individuals were asked to bring 1 or 2 teammates to serve as control participants, who were matched for sex, sport, and age (n = 20; mean ± SD age, 16.9 ± 1.1 years; height, 169.7 ± 8.4 cm; body mass, 70.1 ± 20.7 kg). Functional performance was tested using the broad jump, vertical jump, modified long shuttle, modified pro shuttle, modified agility T-test, timed hop, triple hop, single hop, and crossover hop tests. A 1-way multivariate analysis of variance (MANOVA) was used to evaluate group differences for dependent performance variables.

RESULTS

The functional performance measurements of skills requiring bilateral involvement of both lower extremities showed no group differences between the ACLR and control groups (P>.05). An overall group difference (P = .006) was observed for the combined limb symmetry index (LSI) measures. However, the modified double-limb performance tasks (long shuttle, modified agility T-test, and pro shuttle) were not, independently, sufficiently sensitive to detect limb deficits in individuals with ACL reconstruction. Conversely, the LSI on the distance measures of the single-limb performance tasks all provided moderate to large effect sizes to differentiate between the ACLR and control groups, as the individuals who had ACL reconstruction demonstrated involved limb deficits on all measures (P<.05). Finally, the LSI for the timed hop test was not different between groups (P>.05).

CONCLUSIONS

These findings indicate that, while unilateral deficits are present in individuals following ACL reconstruction, they may not be evident during bipedal performance or during modified versions of double-limb performance activities. Isolation of the involved limb with unilateral hopping tasks should be used to identify deficits in performance.

Nonsurgical treatment of acetabular labrum tears: a case series

STUDY DESIGN

Case series.

BACKGROUND

While the literature has emphasized surgical treatment of acetabular labrum tears, there is a lack of information regarding conservative treatment. The purpose of this case series was to describe a nonsurgical program for those with clinical evidence of an acetabular labrum tear, that emphasized hip and lumbopelvic stabilization, correction of hip muscle imbalance, biomechanical control, and sport-specific functional progression.

CASE DESCRIPTION

The 4 patients in this series had clinical evidence and magnetic resonance imaging confirmation of an acetabular labrum tear and underwent a similar treatment protocol consisting of 3 phases. Phase 1 emphasized pain control, education in trunk stabilization, and correction of abnormal joint movement. Phase 2 focused on muscular strengthening, recovery of normal range of motion (ROM), and initiation of sensory motor training. And phase 3 emphasized advanced sensory motor training, with sport-specific functional progression. ROM, flexibility, pain, special tests, and level of function were assessed, and strength was measured with handheld dynamometry.

OUTCOMES

All patients demonstrated decreased pain, functional improvement, and correction of muscular imbalance. Increased muscle strength, primarily for the hip flexors (1%-39%), abductors (18%-56%), and extensors (68%-139%) was also noted.

DISCUSSION

All patients responded well to our program. This case series suggests that patients with clinical evidence of an acetabular labral tear confirmed with MRI can show meaningful improvement with nonsurgical intervention.

LEVEL OF EVIDENCE

Therapy, level 4.

Longitudinal gait and strength changes prior to and following an anterior cruciate ligament rupture and surgical reconstruction: a case report

STUDY DESIGN

Case report.

BACKGROUND

Cross-sectional studies have examined deficits following anterior cruciate ligament (ACL) rupture and subsequent reconstructive surgery. Few studies present preinjury data that may assist in identifying risk factors for ACL rupture. This case report compares gait and strength measures obtained prior to ACL rupture, with follow-up assessments of these measures after rupture and reconstructive surgery.

CASE DESCRIPTION

A 23-year-old woman sustained a noncontact rupture of her right ACL. Kinematic and kinetic gait data were collected using 3-dimensional motion analysis and a synchronized force plate. Knee strength was measured using an isokinetic dynamometer. Data for knee active range of motion (AROM) and the Lower Extremity Functional Scale (LEFS) were also collected. The analyses were descriptive and interpreted based on previously published minimal detectable change and minimal clinically important difference values.

OUTCOMES

Before her injury, the patient demonstrated a low external knee flexion moment during gait. Kinematic and kinetic gait abnormalities were present following rupture and persisted at 13 months postsurgery. The patient demonstrated knee strength deficits following ACL rupture and surgery. Steady gains in LEFS and knee AROM occurred following rupture and surgery.

DISCUSSION

Preinjury data may identify risk factors for ACL rupture. Future studies should examine whether a low external knee flexion moment during gait or sport-related activity is a risk factor for ACL rupture. The patient demonstrated deficits in gait and strength that persisted at 13 months postsurgery.

LEVEL OF EVIDENCE

Therapy, level 4.

A national survey of the physiotherapy management of patients following first-time patellar dislocation

OBJECTIVES

The purpose of this study was to determine how musculoskeletal physiotherapists in acute National Health Service (NHS) hospitals manage patients following a first time patellar dislocation.

DESIGN

National survey study.

SETTING

All NHS acute hospitals with an accident and emergency and/or an orthopaedic department were surveyed.

PARTICIPANTS

306 institutions were surveyed.

INTERVENTIONS

Each institution was sent a 14 question self-administered questionnaire pertaining to the assessment, treatment, evaluation and outcome of patients following a first time patellar dislocation. After 3 weeks, all non-respondents were sent a reminder letter. After a further 3 weeks, those who had not responded by this time were sent a final reminder and copy of the questionnaire.

RESULTS

The survey response rate was 59%. The respondents indicated that first-time patellar dislocation was not a common musculoskeletal disorder managed by NHS physiotherapists, constituting an average of 2% of caseloads. The results suggested that physiotherapists most commonly assess for reduced quadriceps or VMO capacity, gait, patellar tracking and glide, and knee effusion when examining patients following a first-time patellar dislocation. The most common treatments adopted are reassurance, behaviour modification followed by proprioceptive, knee mobility, quadriceps and specific VMO exercises.

CONCLUSIONS

Generic lower limb assessment and treatment strategies are widely used to manage this patient group. Given the previous paucity in this literature, further study is now recommended to assess the efficacy of these interventions to provide UK physiotherapists with an evidence-base to justify their management strategies.

Walking kinematics in individuals with patellofemoral pain syndrome: a case-control study

Patellofemoral pain syndrome (PFPS) development is considered to be multifactorial with various knee, hip and foot/ankle kinematic factors thought to be involved. A paucity of research evaluating kinematic factors throughout the lower limb kinematic chain simultaneously in individuals with PFPS was identified in a recent systematic review. The objective of this study was to compare kinematics at the knee, hip and foot/ankle in a group of individuals with PFPS to a group of asymptomatic controls. Twenty-six individuals with PFPS and 20 controls aged between 18 and 35 were recruited. Between-group comparisons were made for magnitude and timing of peak angles, and range of motion at the forefoot (dorsiflexion, abduction and supination), rearfoot (dorsiflexion, internal rotation and eversion), knee (flexion, abduction and internal rotation) and hip (adduction and internal rotation) during walking. The PFPS group demonstrated less peak hip internal rotation (7.0° versus 11.8°, p=0.024, p=0.024), earlier peak rearfoot eversion relative to the laboratory (30.4% versus 35.3% of the gait cycle, p=0.010) and tibia (32.7% versus 36.5% of the gait cycle, p=0.030), and greater rearfoot dorsiflexion range of motion relative to the laboratory (72.3° versus 68.2°, p=0.007). Additionally, a trend toward reduced gait velocity (p=0.070) was found in the PFPS group. Reduced peak hip internal rotation and gait velocity in individuals with PFPS may indicate compensation to reduce PFJ load during walking. However, earlier peak rearfoot eversion may be a factor related to the pathomechanical development of the condition.

Influence of patellofemoral pain syndrome on plantar pressure in the foot rollover process during gait

BACKGROUND

Patellofemoral Pain Syndrome is one of the most common knee disorders among physically active young women. Despite its high incidence, the multifactorial etiology of this disorder is not fully understood.

OBJECTIVES

To investigate the influence of Patellofemoral Pain Syndrome on plantar pressure distribution during the foot rollover process (i.e., the initial heel contact, midstance and propulsion phases) of the gait.

MATERIALS AND METHODS

Fifty-seven young adults, including 22 subjects with Patellofemoral Pain Syndrome (30 ± 7 years, 165 ± 9 cm, 63 ± 12 kg) and 35 control subjects (29 ± 7 years, 164 ± 8 cm, 60 ± 11 kg), volunteered for the study. The contact area and peak pressure were evaluated using the Pedar-X system (Novel, Germany) synchronized with ankle sagittal kinematics.

RESULTS

Subjects with Patellofemoral Pain Syndrome showed a larger contact area over the medial (p = 0.004) and central (p = 0.002) rearfoot at the initial contact phase and a lower peak pressure over the medial forefoot (p = 0.033) during propulsion when compared with control subjects.

CONCLUSIONS

Patellofemoral Pain Syndrome is related to a foot rollover pattern that is medially directed at the rearfoot during initial heel contact and laterally directed at the forefoot during propulsion. These detected alterations in the foot rollover process during gait may be used to develop clinical interventions using insoles, taping and therapeutic exercise to rehabilitate this dysfunction.

Measures of range of motion and strength among healthy women with differing quality of lower extremity movement during the lateral step-down test

STUDY DESIGN

Cross-sectional.

OBJECTIVE

To determine the association between hip and ankle range-of-motion measures, as well as measures of hip muscle strength, with measures of quality of lower extremity movement, as assessed visually during the lateral step-down test in healthy women.

BACKGROUND

Altered lower extremity movement pattern consisting of excessive femoral adduction and internal rotation, leading to excessive knee valgus alignment, is associated with increased risk of knee ligament injury, as well as patellofemoral pain syndrome. Previous investigations of lower extremity kinematics, using 3-dimensional motion analysis systems, document an inconsistent association between hip muscle strength and lower extremity movement pattern. Currently, it is unknown whether differences in hip muscle strength or other physical measures exist among women with differing quality of lower extremity movement as assessed by visual observation.

METHODS

Two physical therapists assessed the quality of movement during the lateral step-down among 29 healthy women (mean ± SD age, 24.3 ± 3.2 years). Subjects were instructed on the optimal movement pattern prior to performing the test. The quality of movement was categorized as "good" or "moderate," based on a previously established 6-point scale. Several measures of hip strength (handheld dynamometer) and hip and ankle range of motion (fluid-filled inclinometer and universal goniometer) were also assessed. Differences in strength and range-of-motion measures between women with good and women with moderate quality of movement were assessed with a Mann-Whitney U test.

RESULTS

Both examiners found decreased ankle dorsiflexion range of motion, as measured with the knee bent (P<.05 and P<.01 for examiner 1 and 2, respectively) and in weight bearing (P<.001 and P<.01 for examiner 1 and 2, respectively) among women with a moderate quality of movement compared to women with a good quality of movement on the lateral step-down test.

CONCLUSION

Following receipt of instructions on optimal lower extremity movement pattern, women who demonstrate a moderate quality of movement, as assessed visually during the lateral step-down test, exhibit decreased ankle dorsiflexion range of motion compared to women with a good quality of movement. Clinicians should consider evaluating ankle dorsiflexion range of motion when observing an altered lower extremity movement pattern during the lateral step-down test.

Short-term effects of hip abductors and lateral rotators strengthening in females with patellofemoral pain syndrome: a randomized controlled clinical trial

STUDY DESIGN

Randomized clinical trial.

OBJECTIVE

To investigate the influence of strengthening the hip abductor and lateral rotator musculature on pain and function of females with patellofemoral pain syndrome (PFPS).

BACKGROUND

Hip muscle weakness in women athletes has been the focus of many recent studies and is suggested as an important impairment to address in the conservative treatment of women with PFPS. However, it is still not well established if strengthening these muscles is associated with clinical improvement in pain and function in sedentary females with PFPS.

METHODS

Seventy females (average±SD age, 25±07 years), with a diagnosis of unilateral PFPS, were distributed randomly into 3 groups: 22 females in the knee exercise group, who received a conventional treatment that emphasized stretching and strengthening of the knee musculature; 23 females in the knee and hip exercise group, who performed exercises to strengthen the hip abductors and external rotators in addition to the same exercises performed by those in the knee exercise group; and of the 25 females who did not receive any treatment. The females of the nontreatment group (control) were instructed to maintain their normal daily activities. An 11-point numerical pain rating scale (NPRS) was used to assess pain during stair ascent and descent. The lower extremity functional scale (LEFS) and the anterior knee pain scale (AKPS) were used to assess function. The single-limb single hop test was also used as a functional outcome to measure preintervention and 4-week postintervention function.

RESULTS

The 3 groups were homogeneous prior to treatment in respect to demographic, pain, and functional scales data. Both the knee exercise and the knee and hip exercise groups showed significant improvement in the LEFS, the AKPS, and the NPRS, when compared to the control group (P<.05 and P<.001, respectively). But, when we considered minimal clinically important differences, only the knee and hip exercise group demonstrated mean improvements in AKPS and pain scores that were large enough to be clinically meaningful. For the single-limb single hop test, both groups receiving an intervention showed greater improvement than the control group, but there was no difference between the 2 interventions (P>.05).

CONCLUSION

Rehabilitation programs focusing on knee strengthening exercises and knee strengthening exercises supplemented by hip strengthening exercises were both effective in improving function and reducing pain in sedentary women with PFPS. Improvements of pain and function were greater for the group that performed the hip strengthening exercises, but the difference was significant only for pain rating while descending stairs.

LEVEL OF EVIDENCE

Therapy, level 1b-.

A comparison of hip strength between sedentary females with and without patellofemoral pain syndrome

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To compare the hip strength of sedentary females with either unilateral or bilateral patellofemoral pain syndrome (PFPS) to a control group of sedentary females of similar demographics without PFPS.

BACKGROUND

It has been suggested that hip muscle weakness may be an important factor in the etiology of young female athletes with PFPS. This syndrome is also common in sedentary females and it is unclear if similar findings of hip weakness would be present in this population.

METHODS

Females between 15 and 40 years of age (control group, n = 50; unilateral PFPS, n = 21; bilateral PFPS, n = 29) participated in the study. Strength for all 6 hip muscle groups was measured bilaterally on all subjects using a handheld dynamometer.

RESULTS

The hip musculature of sedentary females with bilateral PFPS was statistically weaker (range, 12%-36%; P<.05) than that of the control group for all muscle groups. The hip abductors, lateral rotators, flexors, and extensors of the injured side of those with unilateral PFPS group were statistically weaker (range, 15%-20%; P<.05)than that of the control group, but only the hip abductors were significantly weaker when compared to their uninjured side (20%; P<.05).

CONCLUSION

This study demonstrates that hip weakness is a common finding in sedentary females with PFPS.

Lower extremity kinematics of females with patellofemoral pain syndrome while stair stepping

STUDY DESIGN

Cross-sectional case-control design.

BACKGROUND

Although the etiology of patellofemoral pain syndrome (PFPS) is not completely understood, there is some evidence to suggest that hip position during weight-bearing activities contributes to the disorder.

OBJECTIVE

To compare the knee and hip motions (and their coordination) during stair stepping in female athletes with and without PFPS.

METHODS

Two groups of female recreational athletes, 1 group with PFPS (n = 10) and a control group without PFPS (n = 10), were tested. All participants ascended and descended stairs (condition) at 2 speeds (self-selected comfortable and taxing [defined as 20% faster than the comfortable speed]), while the knee and hip angles were measured with a magnetic-based kinematic data acquisition system. Angle-angle diagrams were used to examine the relationship between flexion/extension of the knee and flexion/extension, adduction/abduction, and internal/external rotation of the hip. The angle of the knee and the 3 angles of the hip at foot contact on the third step were compared between groups by means of 3-way analyses of variance (ANOVA), with repeated measures on speed and condition.

RESULTS

Group-by-speed interaction for knee angle was significant, with knee flexion being greater for the PFPS group for stair ascent and descent at a comfortable speed. Both the angle-angle diagrams and ANOVA demonstrated greater adduction and internal rotation of the hip in the individuals with PFPS compared to control participants during stair descent.

CONCLUSION

Compared to control participants, females with PFPS descend stairs with the knee in a more flexed position and have the hip in a more adducted and internally rotated position at foot contact during stair stepping at a comfortable speed.

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

STUDY DESIGN

Randomized, crossover study.

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Update on rehabilitation following ACL reconstruction

As anterior cruciate ligament (ACL) reconstruction has evolved to less invasive, more anatomical approaches, rehabilitation of the injured athlete has likewise become more progressive and innovative, with a sound understanding of graft and fixation strength and biologic healing-remodeling constraints. This review discusses these innovations including specific considerations before surgery, when planning rehabilitation timetables, and the importance of reestablishing nonimpaired active and passive knee range of motion and biarticular musculotendinous extensibility in positions of function. Concepts of self-efficacy or confidence and reestablishing the “athlete role” are also addressed. Since ACL injury and reinjury are largely related to the influence of structure-form-function on dynamic knee joint stability, the interrelationships between sensorimotor, neuromuscular, and conventional resistance training are also discussed. Although pivot shift “giving way” relates to function loss following ACL injury, anterior translational laxity often does not. Although there is growing evidence that progressive eccentric training may benefit the patient following ACL reconstruction, there is less evidence supporting the use of functional ACL knee braces. Of considerable importance is selecting and achieving a criteria-based progression to sports-specific training, reestablishing osseous homeostasis and improved bone density, blending open and closed kinetic chain exercises at the appropriate time period, and appreciating the influence of the trunk, upper extremities, and sports equipment use on knee loads. We believe that knee dysfunction and functional recovery should be considered from a local, regional, and global perspective. These concepts are consolidated into our approach to prepare patients for return to play including field testing and maintenance training.

The effect of fatigue on lower-limb biomechanics during single-limb landings: a systematic review

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To evaluate the quality and outcomes of published research papers on the topic of fatigue-induced biomechanical changes in single-limb landings.

BACKGROUND

Lower extremity fatigue causes a number of biomechanical alterations that may increase the risk of knee injury. It has therefore been suggested that fatigue elements be incorporated into injury prevention programs. For this to be successful, protocols that reliably induce fatigue need to be identified and the effect fatigue has on the lower-limb joints needs to be documented.

METHODS

A systematic review was conducted to identify published studies that assessed the effect of fatigue on lower-limb biomechanics during single-limb landing tasks. Studies were identified by searching 6 databases, reference lists, and citation tracking. The methodological quality of each paper was assessed, and effect sizes were calculated to allow comparison of results across studies.

RESULTS

Eight studies met the inclusion criteria. Numerous methodological differences between the studies made synthesis of data challenging. There was some evidence to show that vertical ground reaction forces and hip and knee joint moments were reduced after fatigue. Kinematic changes were less consistent and require further study.

CONCLUSION

The current body of studies showed mixed findings, particularly in relation to landing kinematics after fatigue. Future studies should focus on developing standardized fatigue protocols that include both local and central fatigue effects and monitor progression of fatigue over time. This area of research should be extended to include individuals recovering from musculoskeletal injury or surgery.