Study Design:Prospective randomized longitudinal clinical trial with matched controls. Objectives: To investigate the long-term effect of training on postural control and extremity function after an acute anterior cruciate ligament (ACL) injury. Background: ACL injuries may cause severe problems with recurrent giving way of the knee and reduced functional capacity. The effect of an acute ACL injury and the effect of various training programs on postural control, as well as the relation between postural control and extremity function after such an injury, have not been studied longitudinally. Methods: Sixty-three consecutive patients, 35 men and 28 women (median age 24 years, quartiles 19-33 years), with an acute nonoperated ACL injury, randomized to neuromuscular supervised or self-monitored training, were examined with stabilometry (amplitude and average speed of center of pressure movements) and a one-leg hop test for distance after 6 weeks (stabilometry only), and after 3, 12, and 36 months, and were compared to a control group. Results: Regardless of treatment, center of pressure amplitude was persistently higher in both the injured and uninjured legs during the 3-year follow-up, but average speed was less affected or unaffected compared to the control group. The one-leg hop had normalized in the neuromuscular group at the 12-month follow-up, but was shorter in both Iegs throughout the 3-year period in the self-monitored group. The median value (quartiles) or injured/uninjured legs at 3 months was 150 cm (120-174 cm)/177 cm (140-199 cm), at 12 months was 174 cm (140-200 cm)/180 cm (150-202 cm), and at 36 months was 172 cm (146-200 cm)/178 cm (150-200 cm) in the self-monitored group, compared to the control group (median 186 cm, quartiles 177-216 cm). Conclusions: The higher center of pressure amplitude in both legs over the 3-year period indicate persistently impaired postural control in single-limb stance. However, functional performance, as measured with the one-leg hop test, was restored by neuromuscular training, but not by self-monitored training.

J Orthop Sports Phys Ther 2OOl;31(11):632-644.

Key Words: anterior cruciate ligament injury, functional performance, postural control

Several tests of human conscious knee proprioception have been described, but there is no consensus or reference standard established. Difficulties remain in the separation of information originating from muscles, tendons, and joints, and the tests cannot discriminate between loss of afferent signals or altered activity in the remaining receptors. There is convincing evidence from several descriptive studies that the afferent information is altered after a knee ligament injury and severely disturbed in some patients with anterior cruciate ligament (ACL) injuries. However, an inherent inferior proprioceptive ability may also exist in some individuals, which makes them vulnerable to injuries. The deficits in proprioception have mostly been studied and related to the consciously registered sense, whereas the extent of possible disturbances of the unconscious or reflectory mechanisms is largely unknown. The latter may, at least from a theoretical point of view, be predominantly contributing to the overall afferent regulation, and a possibility for major defects thus exists, since there is no knowledge of the quantified relation between the conscious and unconscious part. The clinical importance of the altered afferent information has not been evaluated properly, and the role of proprioception that contributes to function has yet to be investigated. A higher physiological sensitivity to detecting a passive joint motion closer to full extension has been found both experimentally and clinically, which may protect the joint due to the close proximity to the limit of joint motion. Proprioception has been found to have a relation to subjective knee function, and patients with symptomatic ACL deficiency seem to have larger deficits than asymptomatic individuals. Little is known about whether training can restore defects in sensory information or by which mechanisms possible compensatory pathways are established. In rehabilitation, each patient must, however, create muscle strength, alertness, and stiffness in harmony with the disturbed mechanics of the knee, which are present both after nonoperative treatment of the ACL and after a reconstruction of the ACL.

J Orthop Sports Phys Ther. 2001;31(10):567-576.

Key Words: gait analysis, mechanoreceptors, passive motion, passive positioning, proprioception

Study Design: Nonrandomized prospective study. Objective: To evaluate proprioception in 2 groups of patients with anterior cruciate ligament (ACL) deficiency who had different severity of symptoms. Background: Defective proprioception has previously been found in patients with ACL-deficient knees. It has been suggested that sensory receptors of the ACL and other knee joint ligaments contribute to proprioception and knee joint function and stability. Methods and Measures: A total of 17 patients with ACL deficiency (mean [SD] age, 28.8 ± 5.6 years; range, 22-39 years) with few, if any, symptoms were compared with 20 patients with ACL deficiency (mean [SD] age, 26.6 ± 6.1 years; range, 18-39 years) having instability and episodes of giving way. The groups were compared with each other and with an age-matched reference group of 19 nonimpaired subjects. Their mean (SD) age was 25.6 ± 3.7 years (range, 20-37 years). Three tests of proprioception were used: threshold to detection of passive motion from 2 starting positions (20° and 40° of knee flexion) toward flexion and extension, active reproduction of a 30° passive angle change, and visual reproduction of a 30° passive angle change. The Wilcoxon rank sum test was used for between-group comparisons. Results: Symptomatic patients had higher threshold to detection of passive motion in their injured side in the flexion trial from 20° (median of 1.5° versus median of 0.5°) and in the extension trial from 40° (median of 1.0° versus median of 0.5°) than the asymptomatic patients. No differences were found in the other threshold tests, active or visual reproduction tests. Conclusions: Patients with severe symptoms related to ACL deficiency were found to have inferior proprioceptive ability in some measurements compared with patients with a good knee function. The findings indicate that proprioceptive deficits might influence the outcome of an ACL injury treated nonoperatively.

J Orthop Sports Phys Ther. 1999;29(10):587-594.

Key Words: anterior cruciate ligament, proprioception, threshold