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-