Strategies for enhancing proprioception and neuromuscular control of the knee

The effects of sensorimotor training on knee proprioception and function for patients with knee osteoarthritis: a preliminary report

Objective: To investigate the effects of a sensorimotor training programme in osteoarthritic patients.

Design: Randomized, single-blind, controlled trial.

Setting: Kinesiology laboratory at School of Physical Therapy.

Participants: A total of 60 patients were randomly assigned to the training group and the control group. Only 29 patients (training group, 15; control group, 14) completed the study.

Intervention: The training group underwent a sensorimotor training programme using a sling suspension system complemented by a routine physical therapy. The control group underwent a routine physical therapy.

Main measures: Active joint repositioning, functional testings, and self-reported function with the Western Ontario & McMaster Universities Arthritis Index before and after the eight-week intervention.

Results: There were significant differences between the two groups with respect to the improvement in proprioception as measured by active joint repositioning (the changes in the absolute error were 1.9± 1.7°, training group versus 0.1 ± 2.8°, control group (P<0.05), and in self-reported functional difficulty (33.2 ±35.1, training group versus 8.0± 10.2, control group; P<0.05)). There was no significant difference between the two groups in other outcomes.

Conclusion: A sensorimotor training using a sling suspension system improved the patients' proprioception in the knee joints and their self-reported function. Thus, these exercises may serve as an exercise programme for patients with knee osteoarthritis.

Effects of functional exercise training on performance and muscle strength after meniscectomy: a randomized trial

Muscular deficits and functional limitations have been found years after meniscectomy of the knee. The purpose of this randomized controlled trial was to examine the effect of functional exercise training on functional performance and isokinetic thigh muscle strength in middle-aged patients subsequent to meniscectomy for a degenerative tear. Four years after meniscectomy, 45 patients (29 men, 16 women) were randomized to functional exercise training, supervised by a physical therapist, three times weekly for 4 months or to no intervention. The exercise program comprised of postural stability training and functional strength and endurance exercises for leg and trunk muscles. Outcomes were three functional performance tests and isokinetic muscle strength. Thirty patients (16 exercisers/14 controls) completed the study. Compared with control patients, the exercise group showed significant improvement in one-leg hop (change 8 vs 2 cm; P=0.040), hamstrings strength 60 degrees /s (P=0.033), and quadriceps endurance 180 degrees /s (P=0.001). Functional exercise training was well tolerated and improved functional performance and thigh muscle strength in this group of middle-aged subjects with a previous degenerative meniscal injury and partial meniscectomy.

Factors That Affect the Young Female Athlete

The past 35 years have seen a tremendous increase in the number of female athletes at all ages and abilities. Recent research has shown a myriad of benefits for girls and women who participate in sports. Physical activity positively influences almost every aspect of a young woman's health, from her physiology to her social interactions and mental health. As the level of girls' participation in sports increases, it is important to examine their risk factors for sports-related injuries.

Deficits in neuromuscular control of the trunk predict knee injury risk: a prospective biomechanical-epidemiologic study

BACKGROUND

Female athletes are at significantly greater risk of anterior cruciate ligament (ACL) injury than male athletes in the same high-risk sports. Decreased trunk (core) neuromuscular control may compromise dynamic knee stability.

HYPOTHESES

(1) Increased trunk displacement after sudden force release would be associated with increased knee injury risk; (2) coronal (lateral), not sagittal, plane displacement would be the strongest predictor of knee ligament injury; (3) logistic regression of factors related to core stability would accurately predict knee, ligament, and ACL injury risk; and (4) the predictive value of these models would differ between genders.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

In this study, 277 collegiate athletes (140 female and 137 male) were prospectively tested for trunk displacement after a sudden force release. Analysis of variance and multivariate logistic regression identified predictors of risk in athletes who sustained knee injury.

RESULTS

Twenty-five athletes (11 female and 14 male) sustained knee injuries over a 3-year period. Trunk displacement was greater in athletes with knee, ligament, and ACL injuries than in uninjured athletes (P < .05). Lateral displacement was the strongest predictor of ligament injury (P = .009). A logistic regression model, consisting of trunk displacements, proprioception, and history of low back pain, predicted knee ligament injury with 91% sensitivity and 68% specificity (P = .001). This model predicted knee, ligament, and ACL injury risk in female athletes with 84%, 89%, and 91% accuracy, but only history of low back pain was a significant predictor of knee ligament injury risk in male athletes.

CONCLUSIONS

Factors related to core stability predicted risk of athletic knee, ligament, and ACL injuries with high sensitivity and moderate specificity in female, but not male, athletes.

Sex differences in lower extremity biomechanics during single leg landings

BACKGROUND

Females have an increased incident rate of anterior cruciate ligament tears compared to males. Biomechanical strategies to decelerate the body in the vertical direction have been implicated as a contributing cause. This study determined if females would exhibit single leg landing strategies characterized by decreased amounts of hip, knee, and ankle flexion resulting in greater vertical ground reaction forces and altered energy absorption patterns when compared to males.

METHODS

Recreationally active males (N=14) and females (N=14), completed five single leg landings from a 0.3m height onto a force platform while three-dimensional kinematics and kinetics were simultaneously collected.

FINDINGS

Compared to males, females exhibited (1) less total hip and knee flexion displacements (40% and 64% of males, respectively, P<0.05) and less time to peak hip and knee flexion (48% and 78% of males, respectively, P<0.05), (2) 9% greater peak vertical ground reaction forces (P<0.05), (3) less total lower body energy absorption (76% of males, P<0.05), and (4) 11% greater relative energy absorption at the ankle (P<0.05).

INTERPRETATION

Females in this study appear to adopt a single leg landing style using less hip and knee flexion, absorbing less total lower body energy with more relative energy at the ankle resulting in a landing style that can be described as stiff. This may potentially cause increased demands on non-contractile components of the lower extremity. Preventative training programs designed to prevent knee injury may benefit from the biomechanical description of sex-specific landing methods demonstrated by females in this study by focusing on the promotion of more reliance on using the contractile components to absorb impact energy during landings.

Validity and reliability of functional performance tests in meniscectomized patients with or without knee osteoarthritis

AIMS

Reduced functional performance and muscular dysfunction after knee injury and in knee osteoarthritis (OA) is suggested to be a factor in OA development. Validated functional performance tests applicable in the clinic and large-scale studies are lacking. The aim was to study the reliability and validity of 10 functional performance tests.

METHODS

Two hundred and eighty-five subjects, 15-22 years post-meniscectomy, performed 10 functional performance tests. The mean age was 54 years (SD+/-11.2) and 79% were men; 52% had radiographic OA, and 48% were categorized as symptomatic. The tests were evaluated for test-retest reliability, discriminative ability (younger vs older age, men vs women, symptom-free vs symptomatic) and floor and ceiling effects.

RESULTS

Two of the 10 tests, maximum number of knee bendings in 30 s and one-leg hop for distance, had good test-retest reliability (ICC 0.92, 95% CI 0.86-0.96 and 0.93, 95% CI 0.87-0.97) and were able to discriminate with regard to age, gender and symptoms, and had acceptable floor effects (9% and 3%, respectively).

CONCLUSION

This study suggests the use of two functional performance tests: knee bendings/30 s and one-leg hop for distance, easy to use for evaluation of interventions due to knee injury and knee OA and when attaining long-term data of natural disease history.

The effects of core proprioception on knee injury: a prospective biomechanical-epidemiological study

BACKGROUND

In sports involving pivoting and landing, female athletes suffer knee injury at a greater rate than male athletes.

HYPOTHESES

Proprioceptive deficits in control of the body's core may affect dynamic stability of the knee. Female, but not male, athletes who suffered a knee injury during a 3-year follow-up period would demonstrate decreased core proprioception at baseline testing as compared with uninjured athletes.

STUDY DESIGN

Cohort study (prognosis); Level of evidence, 2.

METHODS

Study subjects were 277 collegiate athletes (140 female, 137 male) who were prospectively tested for core proprioception by active and passive proprioceptive repositioning. Athletes were monitored for injury for 3 years. An ANOVA and multivariate logistic regression were used to test whether core proprioception was related to knee injuries in athletes.

RESULTS

Twenty-five athletes sustained knee injuries (11 women, 14 men). Deficits in active proprioceptive repositioning were observed in women with knee injuries (2.2 degrees ) and ligament/meniscal injuries (2.4 degrees ) compared with uninjured women (1.5 degrees , P <or= .05). There were no differences in average active proprioceptive repositioning error between injured men and uninjured men (P >or= .05). Uninjured women demonstrated significantly less average error in active proprioceptive repositioning than uninjured men (1.5 degrees vs 1.7 degrees , P <or= .05). For each degree increase in average active proprioceptive repositioning error, a 2.9-fold increase in the odds ratio of knee injury was observed, and a 3.3-fold increase in odds ratio of ligament/meniscal injury was observed (P <or= .01). Active proprioceptive repositioning predicted knee injury status with 90% sensitivity and 56% specificity in female athletes.

CONCLUSIONS

Impaired core proprioception, measured by active proprioceptive repositioning of the trunk, predicted knee injury risk in female, but not male, athletes.

The Characteristics of Foot Movements in Tai Chi Chuan

This study examines how the characteristics of the foot movements in Tai Chi Chuan (TCC) contribute to a practitioner's health by improving his or her balance and reducing the risk of fall. Ten TCC masters are video-taped, and the time spent on different support patterns (step stance) and stepping directions (footwork) while performing the 42-form TCC is analyzed. In support patterns, it is found that a larger percentage of time is spent on the double leg stance (35.08 +/- 4.92) than on the single leg stance (Left: 17.67 +/- 7.71; Right: 17.29 +/- 2.23) and one leg support with another leg partially supporting type of stance (6.51 +/- 8.77). With regard to stepping directions, the centre footwork (25.25 +/- 10.20) requires a larger percentage of time than the forward (18.29 +/- 3.36), sideway (20.80 +/- 4.76), grinding (20.42 +/- 7.61), upward (11.55 +/- 1.49), and backward footwork (3.67 +/- 1.33). The movements classified are shown to simulate balance, flexibility and proprioception, and functional training. The findings partially explain the relationship between practising TCC and its health benefits. Further studies are suggested to investigate the health benefits that can be derived from other specific TCC movements.

Clinical measurements of proprioception, muscle strength and laxity in relation to function in the ACL-injured knee

A knee injury with anterior cruciate ligament (ACL) rupture may cause deficits in proprioception, increased laxity and decreased muscle strength. Although it may be common knowledge that these factors affect knee function, only a few studies have been performed where this has been investigated in the clinical situation, and the results are not conclusive. The purpose of this study was therefore to investigate how and to what extent proprioception, laxity and strength affect knee joint function and evaluate if the methods commonly used for estimating these factors clinically seem to be relevant. The study encompassed 36 patients with ACL deficiency. A single-leg hop test for distance and subjective rating of knee function were defined as dependent variables and analyzed separately in stepwise linear regression models where proprioception, knee joint laxity, hamstrings and quadriceps strength, age and sex were defined as independent variables. Higher threshold values (poorer proprioception), increased side-to-side difference of anterior laxity and poorer strength significantly predicted shorter length of the hop test. Higher rating of subjective function corresponded to female gender, lesser side-to-side difference of anterior laxity and better proprioception.

Dimorphism and patellofemoral disorders

Sex is defined as the classification of living things according to their chromosomal compliment. Gender is defined as a person's self-representation as a male or female or how social institutions respond to that person on the basis of his or her gender presentation. One frequently divides the topic or dimorphism into the biologic response inherent in their sex and the environmental response that might be better termed "gender differences." Clinicians have anecdotally agreed for years that patellofemoral disorders are more common in women. Given the difficulty in classifying patellofemoral disorders, literature support for this assumption is meager. For the purposes of this article we divide patellofemoral disorders into three categories: patellofemoral pain, patellofemoral instability, and patellofemoral arthritis. possible sex difference in these disorders are reviewed.

Gender and limb differences in dynamic postural stability during landing

OBJECTIVE

To determine if gender and limb dominance affect dynamic postural stability and vertical ground reaction force data during jump landings. Secondary objective was to assess the reliability of the dynamic postural stability index (DPSI).

DESIGN

A mixed model (2 genderx2 limb) repeated measures design was used to determine the effects of gender and limb dominance on dynamic postural stability. Subjects were required to perform a two-legged jump to a height equivalent of 50% of their maximum vertical leap, land on a single-leg and balance for three seconds.

SETTING

Sports Medicine Research Laboratory.

PARTICIPANTS

Forty healthy subjects (20 men, 20 women) participated in this investigation.

MAIN OUTCOME MEASURES

The DPSI and its directional components quantified dynamic postural stability during a single-leg jump landing. Normalized vertical ground reaction force data quantified energy absorption.

RESULTS

DPSI values revealed that females had significantly different dynamic postural stability as compared to males in the vertical plane [T (78)=-4.2, P<0.01], and in the composite score (dynamic postural stability index) [T (78)=-6.3, P<0.01]. In addition, females had significantly higher peak vertical ground reaction forces [T (78)=-13, P=0.01] than males. The DPSI also showed excellent reliability (ICC=0.96), with a 95% confidence interval ranging from 0.94 to 0.97.

CONCLUSIONS

The results indicate that females have higher dynamic postural stability scores in the vertical direction as well as the composite score. This suggests that females used different dynamic postural stability strategies than males. There were no side-to-side dynamic postural stability differences between healthy contralateral limbs.

Comparison of proprioceptive functions between computerized proprioception facilitation exercise and closed kinetic chain exercise in patients with knee osteoarthritis

AIM

The aim of this study was to compare proprioceptive function between computerized proprioception facilitation exercise (CPFE) and closed kinetic chain exercise (CKCE) for knee osteoarthritis.

DESIGN

Randomized-controlled.

SETTING

Kinesiology laboratory.

PATIENTS

Eighty-one patients with bilateral knee osteoarthritis were randomly assigned to CPFE, CKCE, and control groups.

INTERVENTION

Both exercise groups underwent an 8-week program of three sessions per week. The control group received no training. The CPFE program included a 20-min computer game to be played by the trained foot of the subject. CKCE included 10 sets of 10 repetitions of repeated knee extension and flexion with resistance of 10-25% of body weight.

MAIN OUTCOME MEASURES

Absolute reposition error, functional score, walking speed, and knee muscle strength were assessed with an electrogoniometer, the physical function subscale of Western Ontario and McMaster Osteoarthritis Index, a CASIO stopwatch, and a Cybex 6000 dynamometer before and after the 8-week period.

RESULTS

The results of this study showed that both CPFE and CKCE were effective in improving joint position sense, functional score, walking speed, and muscle strength. Furthermore, CKCE showed greater effect in increasing knee extensor torque in patients with knee osteoarthritis.

CONCLUSION

Clinical effects of CPFE were the same as those of CKCE except for knee extensor torque. The increase in knee extensor torque in CPFE patients was not as great as that seen in CKCE patients.

Rehabilitation after anterior cruciate ligament reconstruction: criteria-based progression through the return-to-sport phase

Rehabilitation following anterior cruciate ligament (ACL) reconstruction has undergone a relatively rapid and global evolution over the past 25 years. However, there is an absence of standardized, objective criteria to accurately assess an athlete's ability to progress through the end stages of rehabilitation and safe return to sport. Return-to-sport rehabilitation, progressed by quantitatively measured functional goals, may improve the athlete's integration back into sport participation. The purpose of the following clinical commentary is to introduce an example of a criteria-driven algorithm for progression through return-to-sport rehabilitation following ACL reconstruction. Our criteria-based protocol incorporates a dynamic assessment of baseline limb strength, patient-reported outcomes, functional knee stability, bilateral limb symmetry with functional tasks, postural control, power, endurance, agility, and technique with sport-specific tasks. Although this algorithm has limitations, it serves as a foundation to expand future evidence-based evaluation and to foster critical investigation into the development of objective measures to accurately determine readiness to safely return to sport following injury.

Benefits of active motion for joint position sense

Anterior cruciate ligament (ACL) ruptures lead to a proprioceptive deficit and therefore joint position sense. This study examined whether active motion is better suited than passive motion to address this deficit. Sixty patients with ACL rupture were prospectively randomised into two groups [continuous active motion (CAM)/continuous passive motion (CPM)]. All patients had an ACL reconstruction. An angle reproduction test was used to assess the proprioceptive deficit. The relevant examinations were performed before surgery (pre-op evaluation) and after the seventh postoperative day. No preoperative difference was found between the two groups. After postoperative treatment, the deficit was reduced in both groups. Significantly better results were, however, obtained in the CAM group (CPM, 4.2+/-1.6 degrees; CAM, 1.9+/-1.2 degrees; P<0.001). During the first postoperative week, a CAM device produced a significantly greater reduction in the proprioceptive deficit and should be the first choice in immediately postoperative rehabilitation after ACL replacement.

Autologous chondrocyte implantation postoperative care and rehabilitation: science and practice

Autologous chondrocyte implantation is an advanced, cell-based orthobiological technology used for the treatment of chondral defects of the knee. It has been in clinical use since 1987 and has been performed on 12 000 patients internationally; but despite having been in clinical use for more than 15 years, the evidence base for rehabilitation after autologous chondrocyte implantation is notably deficient. The authors review current clinical practice and present an overview of the principles behind autologous chondrocyte implantation rehabilitation practices. They examine the main rehabilitation components and discuss their practical applications within the overall treatment program, with the aim of facilitating the formulation of appropriate, individualized patient rehabilitation protocols for autologous chondrocyte implantation.

[The influence of a controlled active motion splint on proprioception after anterior cruciate ligament plasty. A prospective randomized study]

BACKGROUND

A ruptured anterior cruciate ligament (ACL) leads to both mechanical and functional instability. Functional instability is caused by proprioceptive deficit. The aim of this study was to determine whether the proprioceptive deficit can be reduced by using a controlled active motion (CAM) splint postoperatively.

PATIENTS AND METHODS

A total of 50 patients with ACL rupture were randomized into two groups. After ACL plasty the PT group received postoperative physiotherapy, while the CAM group were managed with a CAM splint and physiotherapy. Proprioceptive ability was measured with a passive angle-reproduction test.

RESULTS

On the day of discharge 80% of the patients in the CAM group and 25% in the PT group had a reduced proprioceptive deficit. Overall the main measured value in the CAM group improved by 83.7%, but deteriorated by 39.3% in the PT group. There was no significant difference between the CAM group and a healthy control group.

CONCLUSION

Using a CAM splint in addition to physiotherapy after ACL plasty in comparison to physiotherapy alone decreases the proprioceptive deficit significantly. We recommend the use of a CAM splint in the postoperative management following ACL plasty.

Maturation leads to gender differences in landing force and vertical jump performance: a longitudinal study

BACKGROUND

Female athletes have increased risk of anterior cruciate ligament rupture after the onset of puberty.

HYPOTHESES

Male athletes would demonstrate a longitudinal increase in vertical jump height compared with female athletes. There would be longitudinal gender differences in ground-reaction forces and loading rates.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Sixteen female and 17 male adolescent athletes were evaluated for 2 consecutive years. Subjects were included if they were classified as pubertal during the first year of testing and postpubertal during the second year. As subjects performed a drop vertical jump, ground-reaction force, and vertical jump height were measured. Data analysis consisted of a mixed design analysis of variance with post hoc analysis (paired t tests).

RESULTS

The male athletes demonstrated increased vertical jump height with maturation (P < .001); female athletes did not. Boys significantly reduced their landing ground-reaction force (P = .005), whereas girls did not. Takeoff force decreased in girls (P = .003) but not in boys. Both boys and girls had decreased loading rates with maturation (P < .001); however, girls had higher loading rates than did boys at both stages of maturation (P = .037).

CONCLUSION

Male athletes demonstrated a neuromuscular spurt as evidenced by increased vertical jump height and increased ability to attenuate landing force. The absence of similar adaptations in female athletes may be related to the increased risk of anterior cruciate ligament injury.

Anterior cruciate ligament injuries in female athletes: Part 2, a meta-analysis of neuromuscular interventions aimed at injury prevention

Female athletes have a 4 to 6 times higher incidence of anterior cruciate ligament injury than do male athletes participating in the same landing and pivoting sports. This greater risk of anterior cruciate ligament injury, coupled with a geometric increase in participation (doubling each decade), has led to a significant rise in anterior cruciate ligament injuries in female athletes. The gender gap in anterior cruciate ligament injury, combined with evidence that the underpinnings of this serious health problem are neuromuscular in nature, leads to the development of neuromuscular interventions designed to prevent injury. A systematic review of the published literature yielded 6 published interventions targeted toward anterior cruciate ligament injury prevention in female athletes. Four of 6 significantly reduced knee injury incidence, and 3 of 6 significantly reduced anterior cruciate ligament injury incidence in female athletes. A meta-analysis of these 6 studies demonstrates a significant effect of neuromuscular training programs on anterior cruciate ligament injury incidence in female athletes (test for overall effect, Z = 4.31, P < .0001). Examination of the similarities and differences between the training regimens gives insight into the development of more effective and efficient interventions. The purpose of this "Current Concepts" review is to highlight the relative effectiveness of these interventions in reducing anterior cruciate ligament injury rates and to evaluate the common training components between the training studies. In addition, the level of rigor of these interventions, the costs and the difficulty of implementation, the compliance with these interventions, and the performance benefits are discussed. This review summarizes conclusions based on evidence from the common components of the various interventions to discuss their potential to reduce anterior cruciate ligament injury risk and assess their potential for combined use in more effective and efficient intervention protocols.

Measurement and Evaluation of Dynamic Joint Stability of the Knee and Ankle After Injury

Injuries to the lower extremity, specifically the knee and ankle joints of the human body can occur in any athletic event and are most prevalent in sports requiring cutting and jumping manoeuvres. These joints are forced to rely on the dynamic restraints to maintain joint stability, due to the lack of bony congruence and the inability of the static restraints to handle the forces generated during functional tasks. Numerous variables (proprioception, postural control, electromyography, kinetics/kinematics, dynamic stability protocols) have been measured to better understand how the body maintains joint stability during a wide range of activities from static standing to dynamic cutting or landing from a jump. While the importance of dynamic restraints is not questioned, a recent impetus to conduct more functional or sport-specific testing has emerged and placed a great deal of emphasis on dynamic joint stability and how it is affected by lower extremity injuries. Evidence suggests that surgery and aggressive rehabilitation will not necessarily restore the deficits in dynamic joint stability caused by injury to the anterior cruciate ligament or lateral ankle ligaments. In today's athletic society, there is a major push to return athletes to play as quickly as possible. However, the ramifications of those decisions have not been fully grasped. If an athlete is not fully recovered, a quick return to play could start a vicious cycle of chronic injuries or permanent disability.

Gender comparison of hip muscle activity during single-leg landing

STUDY DESIGN

Controlled laboratory study.

OBJECTIVES

To determine whether gender differences in electromyographic (EMG) activity of hip-stabilizing muscles are present during single-leg landing.

BACKGROUND

Numerous factors may explain the greater rate of anterior cruciate ligament (ACL) injuries in female athletes. However, gender differences in hip muscle activity during dynamic events have not been well characterized.

METHODS AND MEASURES

Twenty-two Division I collegiate athletes (13 female, 9 male) performed drop landings from 30.5- and 45.8-cm heights. Surface EMG was used to examine relative muscle activity from 200 milliseconds prior to initial contact to 250 milliseconds postcontact. Peak and mean values for each muscle (gluteus maximus, gluteus medius, rectus femoris) in each time epoch were analyzed using 2 x 2 (group by height) analyses of variance (ANOVAs) to determine significance.

RESULTS

Females demonstrated lower gluteus maximus peak (mean +/- SD, 69.5 +/- 30.2 versus 98.0 +/- 33.4 percent maximum voluntary contraction [%MVIC]; P= .019) and mean (mean +/- SD, 37.5 +/- 15.6 versus 53.9 +/- 18.0 %MVIC; P = .018) muscle activation during the postcontact phase of landing than males. Furthermore, females demonstrated greater peak rectus femoris activity during the precontact phase (mean +/- SD, 33.6 +/- 18.5 versus 18.7 +/- 8.2 %MVIC; P = .029). A positive effect of drop height on relative activity of all muscles was observed during both phases (P<.05).

CONCLUSIONS

Females utilize different muscular activation patterns compared to males (ie, decreased gluteus maximus and increased rectus femoris muscle activity) during landing maneuvers. Decreased hip muscle activity and increased quadriceps activity may be important contributors to the increased susceptibility of female athletes to noncontact ACL injuries.

Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospective study

BACKGROUND

Female athletes participating in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than do male athletes.

HYPOTHESIS

Prescreened female athletes with subsequent anterior cruciate ligament injury will demonstrate decreased neuromuscular control and increased valgus joint loading, predicting anterior cruciate ligament injury risk.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

There were 205 female athletes in the high-risk sports of soccer, basketball, and volleyball prospectively measured for neuromuscular control using 3-dimensional kinematics (joint angles) and joint loads using kinetics (joint moments) during a jump-landing task. Analysis of variance as well as linear and logistic regression were used to isolate predictors of risk in athletes who subsequently ruptured the anterior cruciate ligament.

RESULTS

Nine athletes had a confirmed anterior cruciate ligament rupture; these 9 had significantly different knee posture and loading compared to the 196 who did not have anterior cruciate ligament rupture. Knee abduction angle (P<.05) at landing was 8 degrees greater in anterior cruciate ligament-injured than in uninjured athletes. Anterior cruciate ligament-injured athletes had a 2.5 times greater knee abduction moment (P<.001) and 20% higher ground reaction force (P<.05), whereas stance time was 16% shorter; hence, increased motion, force, and moments occurred more quickly. Knee abduction moment predicted anterior cruciate ligament injury status with 73% specificity and 78% sensitivity; dynamic valgus measures showed a predictive r2 of 0.88.

CONCLUSION

Knee motion and knee loading during a landing task are predictors of anterior cruciate ligament injury risk in female athletes.

CLINICAL RELEVANCE

Female athletes with increased dynamic valgus and high abduction loads are at increased risk of anterior cruciate ligament injury. The methods developed may be used to monitor neuromuscular control of the knee joint and may help develop simpler measures of neuromuscular control that can be used to direct female athletes to more effective, targeted interventions.

Sports-related knee injuries in female athletes: what gives?

Knee injuries occur commonly in sports, limiting field and practice time and performance level. Although injury etiology relates primarily to sports specific activity, female athletes are at higher risk of knee injury than their male counterparts in jumping and cutting sports. Particular pain syndromes such as anterior knee pain and injuries such as noncontact anterior cruciate ligament (ACL) injuries occur at a higher rate in female than male athletes at a similar level of competition. Anterior cruciate ligament injuries can be season or career ending, at times requiring costly surgery and rehabilitation. Beyond real-time pain and functional limitations, previous injury is implicated in knee osteoarthritis occurring later in life. Although anatomical parameters differ between and within the sexes, it is not likely this is the single reason for knee injury rate disparities. Clinicians and researchers have also studied the role of sex hormones and dynamic neuromuscular imbalances in female compared with male athletes in hopes of finding the causes for the increased rate of ACL injury. Understanding gender differences in knee injuries will lead to more effective prevention strategies for women athletes who currently suffer thousands of ACL tears annually. To meet the goal in sports medicine of safely returning an athlete to her sport, our evaluation, assessment, treatments and prevention strategies must reflect not only our knowledge of the structure and innervations of the knee but neuromuscular control in multiple planes and with multiple forces while at play.

Anterior and posterior cruciate ligament injuries

Knee pain is a common complaint in the primary care setting, and ACL and PCL injuries are common causes of knee pain. Therefore, it is important for the primary care physician to be skilled in the diagnosis and initial management of these injuries and to be aware of potential associated knee injuries. By understanding the history, mechanism of injury, physical examination maneuvers, and imaging modalities related to ACL and PCL injuries, primary care physicians can prepare themselves to make an accurate diagnosis. Then they can counsel the patients on the available treatments, initiate conservative treatment if appropriate, and facilitate an effective referral to a primary care sports medicine physician or orthopedic surgeon.

Methodological approaches and rationale for training to prevent anterior cruciate ligament injuries in female athletes

Female athletes have a four- to sevenfold increased risk of anterior cruciate ligament (ACL) injury compared with their male counterparts playing at similar levels in the same sports. The elevated risk of ACL injury in females coupled with the geometric increase in female sports participation in the last 30 years has led to a rapid rise in these injuries. This large increase in ACL injury incidence has fueled studies into both mechanisms of injury and interventions to prevent injury. A review of published multidisciplinary approaches demonstrates that several training protocols have utilized multiple components targeted toward injury prevention training and were able to reduce injury incidence in female athletes. Similar training techniques may also be used to gain improvements in measures of performance. The purpose of this review is to highlight training components that may reduce ACL injury risk and assess their potential for combined use in performance-oriented protocols.

Rehabilitation following anterior cruciate ligament injury: current recommendations for sports participation

Knee ligament injuries often result in a premature end to a career in sports. The treatment after rupture of the anterior cruciate ligament (ACL) may be operative or conservative. In both cases, the goal is to reach the best functional level for the patient without risking new injuries or degenerative changes in the knee. Return to high level of athletic activity has been an indicator of treatment success. Rehabilitation is an important part of the treatment. Knowledge of healing processes and biomechanics in the knee joint after injury and reconstruction, together with physiological aspects on training effects is important for the construction of rehabilitation programmes. Current rehabilitation programmes use immediate training of range of motion. Weight bearing is encouraged within the first week after an ACL reconstruction. Commonly, the patients are allowed to return to light sporting activities such as running at 2-3 months after surgery and to contact sports, including cutting and jumping, after 6 months. In many cases, the decisions are empirically based and the rehabilitation programmes are adjusted to the time selected for returning to sports. In this article, some criteria that should be fulfilled in order to allow the patient to return to sports are presented. Surgery together with completed rehabilitation and sport-specific exercises should result in functional stability of the knee joint. In addition, adequate muscle strength and performance should be used as a critical criterion. Other factors, such as associated injuries and social and psychological hindrances may also influence the return to sports and must be taken into consideration, both during the rehabilitation and at the evaluation of the treatment.

Decrease in neuromuscular control about the knee with maturation in female athletes

BACKGROUND

Compared with male athletes, female athletes demonstrate increased dynamic valgus angulation of the knee during landing from a jump, although prior to maturation male and female athletes have similar forces and motions about the knee when they land from a jump. Our hypothesis was that musculoskeletal changes that accompany maturation result in poor neuromuscular control of the knee joint in female athletes.

METHODS

One hundred and eighty-one middle-school and high-school soccer and basketball players-100 girls and eighty-one boys-participated in the study. Dynamic control of the knee joint was measured kinematically by assessing medial knee motion and the lower-extremity valgus angle and was measured kinetically by assessing knee joint torques; the values were then compared between female and male athletes according to maturational stage. Lower-extremity bone length was measured with three-dimensional kinematic analysis.

RESULTS

Following the onset of maturation, the female athletes landed with greater total medial motion of the knees and a greater maximum lower-extremity valgus angle than did the male athletes. The girls also demonstrated decreased flexor torques compared with the boys as well as a significant difference between the maximum valgus angles of their dominant and nondominant lower extremities after maturation.

CONCLUSIONS

After girls mature, they land from a jump differently than do boys, as measured kinematically and kinetically.

Injury mechanisms for anterior cruciate ligament injuries in team handball: a systematic video analysis

OBJECTIVE

To describe the mechanisms for anterior cruciate ligament injuries in female team handball.

STUDY DESIGN

Descriptive video analysis.

METHODS

Twenty videotapes of anterior cruciate ligament injuries from Norwegian or international competition were collected from 12 seasons (1988-2000). Three medical doctors and 3 national team coaches systematically analyzed these videos to describe the injury mechanisms and playing situations. In addition, 32 anterior cruciate ligament-injured players in the 3 upper divisions in Norwegian team handball were interviewed during the 1998-1999 season to compare the injury characteristics between player recall and the video analysis.

RESULTS

Two main injury mechanisms for anterior cruciate ligament injuries in team handball were identified. The most common (12 of 20 injuries), a plant-and-cut movement, occurred in every case with a forceful valgus and external or internal rotation with the knee close to full extension. The other main injury mechanism (4 of 20 injuries), a 1-legged jump shot landing, occurred with a forceful valgus and external rotation with the knee close to full extension. The results from the video analysis and questionnaire data were similar.

CONCLUSIONS

The injury mechanism for anterior cruciate ligament injuries in female team handball appeared to be a forceful valgus collapse with the knee close to full extension combined with external or internal rotation of the tibia.

Neuromuscular training improves single-limb stability in young female athletes

STUDY DESIGN

Controlled single-group pretest/posttest design.

OBJECTIVE

The purpose of this study was to determine if a 6-week neuromuscular training program designed to decrease the incidence of anterior cruciate ligament (ACL) injuries would improve single-limb postural stability in young female athletes. We hypothesized neuromuscular training would result in an improvement in postural stability, with the greatest improvement taking place in the medial-lateral direction.

BACKGROUND

Balance training has become a common component of programs designed to prevent ACL injury. Rehabilitation programs can improve postural stability following ACL injury and reconstruction; however, there is limited information available which quantifies improvement of postural stability following neuromuscular training designed to prevent ACL injuries in a healthy population.

METHODS AND MEASURES

Forty-one healthy female high school athletes (mean age, 15.3 years; age range, 13-17 years) participated in this study. Single-limb postural stability for both lower extremities was assessed with a Biodex Stability System. The neuromuscular training program consisted of three 90-minute training sessions per week for 6 weeks. Following the completion of the training program, each subject was re-evaluated to determine change in total, anterior-posterior, and medial-lateral single-limb stability. Two-way analysis of variance models were used to determine differences between pretraining and posttraining and between limbs.

RESULTS

The subjects showed a significant improvement in single-limb total stability (P = .004) and anterior-posterior stability (P = .001), but not medial-lateral stability (P = .650) for both the right and left lower extremity following training. In addition, the subjects demonstrated significantly better total postural stability on the right side as compared to the left (P = .026).

CONCLUSIONS

A 6-week neuromuscular training program designed to decrease the incidence of ACL injuries improves objective measures of total and anterior-posterior single-limb postural stability in high school female athletes.