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.

J Orthop Sports Phys Ther. 2004;34(6):305-316. doi:10.2519/jospt.2004.1325

Key Words: anterior cruciate ligament, balance, knee, prevention, proprioception

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 ×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.

J Orthop Sports Phys Ther. 2005;35(5):292-299. doi:10.2519/jospt.2005.1734

Key Words: ACL, hip stability, knee

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 this 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.

J Orthop Sports Phys Ther. 2006; 36(6):385-402. doi:10.2519/jospt.2006.2222

Key Words: anterior cruciate ligament, knee rehabilitation, lower extremity, sport injury