Eva Ageberg, RP7; MS$ Markus W a l d h , M9 Rose Zatferstrom, RP7; P h D 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. ) Orthop Sports Phys Ther 2001;3 1:567-576.

Stabilometry is a technique designed to register postural equilibrium control. This investigation used a computerized strain gauge force plate to measure sway movements in the frontal plane with the patient standing on one leg. Fifty-five young healthy individuals were studied as a reference group and to determine the reproducibility of the method. The clinical population consisted of 14 patients with unilateral injuries to the lateral ligaments of the ankle. These were measured, both with and without an ankle brace. The different parameters used to describe the body sway could well discriminate between the injured and the uninjured leg. When the brace was used the effect was obvious and none of the parameters showed any significant difference compared to the uninjured leg.

D c~( I I . / I I I~~I~ AbstractAn external device ("rottometer") specially designed to measure knee joint rotation was developed and evaluated with respect to its validity. Simultaneous measurements were made with the rottometer and Roentgen stereometric analysis (RSA) in five patients with implanted tantalum markers in the tibia and femur. Measurements of internal and external rotation were made at 90" and 60" of knee flexion using 3, 6 and 9 N m torques. The coefficients of determination ( r 2 ) between the results obtained with the rottometer and RSA were around 0.9 for the total rotation. The rottometer consistently overestimated the rotation by about loo'%, and this systematic error was most constant at 90" Aexion for the different torques. The magnitude of this error from soft tissue deformation as well as the rotatory movements in the hip, foot and ankle joints must be considered when using external devices to measure knee rotation in clinical studies. The most accurate registrations were found in 90" flexion with 9 N ni force (r2 = 0.94).

Body sway movements in the frontal plane in a single-limbed stance test were used to assess postural control in 26 patients with chronic anterior cruciate ligament insufficiency. The injured and the noninjured legs were tested before the patients were committed to physiotherapy for 3 to 6 months. Follow-up tests were made after 3, 12, and 36 months. Significant disturbance of the balance of both legs was found before training, compared with a reference group of normal subjects. Values of the noninjured leg were normalized after 3 months of training, but the injured leg still showed an increased body sway. Normal balance parameters on the injured side were found at examination after 12 months. Follow-up examination after 36 months proved persistent normalization of the single-limbed balance on both sides.

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. Resulb: 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 neure muscular group at the 12-month follow-up, but was shorter in both I s throughout the 3-

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 [SDl age, 28.8 t 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 t 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" vs median of 0.57 and in the extension trial from 40' (median of 1 .OO vs median of 0.5" than the asymptomatic patients. No differences were found in the other threshold tests, active or visual reproduction tests. Conclusiw: 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;29:587-594. Key Words: anterior cmciate ligament, proprioception, threshold

The efficacy of two non-operative rehabilitation programs was studied in a consecutive randomized controlled clinical trial of 100 patients after 12 months subsequent to an acute anterior cruciate ligament (ACL) injury. Follow up of randomization to two training models was evaluated after 3 and 12 months: A self-monitored training program (SM) of traditional mobility and muscle strength training of the injured leg was compared to a supervised (SV) training model exercising postural function in closed kinetic-chains. Nearly 50% of the patients in the SM group required supervision after 6 weeks. An intention-to-treat analysis was performed and showed significantly better values in most of the results of the supervised group at 3 and 12 months. An alternative analysis of subgroups showed a significant difference between transferred male patients and original SV male patients at 3 months but not at 12 months, indicating the importance of initial guiding after an ACL injury. No such difference was observed in the female patients.

A defect in proprioception has been found in selected patient groups that have an anterior cruciate ligament deficient knee at different times after the original injury. The time of development and the extent of such defects were studied longitudinally on 16 consecutive patients. During the first year after a primary knee injury, which included a complete rupture of the anterior cruciate ligament, we repeatedly performed three tests of proprioception: (a) one to determine the threshold for detecting a passive motion from starting positions of 20 and 40 degrees, (b) an active reproduction of a passive angular change, and (c) a visual estimation of a passive angular change. The injured limb was compared with the uninjured limb and with the limbs of an age-matched reference group of healthy subjects. The population did not have a normal distribution, and some patients had consistently extreme recordings in the threshold tests at the various times of testing. Significant differences were found between the groups at the starting position of 20 degrees, when the injured knee was compared with the uninjured knee, after 1 month (p = 0.05), and after 2 months (p = 0.03). There was a trend toward a higher threshold for detecting a passive motion when the injured side was compared with the knees of the reference group at 1 month (p = 0.06) but not later on. A similar pattern was found for the injured knee at the starting position of 40 degrees, but it was not significant. An impaired ability to detect a passive motion was registered for the nearly extended knee 1 and 2 months after a primary injury. In the active reproduction and visual estimation tests, no significant defects were found at any time during the first year in these consecutively studied patients.