JOINT POSITION SENSE AND REHABILITATION IN THE ANTERIOR CRUCIATE LIGAMENT DEFICIENT KNEE

Background-Impaired joint position sense UPS) has been shown in anteri or cruciate ligament (ACL) deficient and osteoarthritic knees. The rel ation between JPS and function is uncertain. The aim of this study was to determine further if ACL deficient knees show abnormal JPS and the effect of exercise therapy on JPS, and also to assess the relation be tween JPS, functional stability, and strength. Methods-Fifty patients (46 men and four women, mean age 26.3 years) with unilateral ACL defic ient knees were assessed on admission and after rehabilitation (5 hour s a day for four weeks). JPS was assessed by reproduction of passive p ositioning using a visual analogue incorporating a goniometer. Knee st ability was analysed by self report questionnaire (score 0-280) and fu nctional activity test (single leg hop and figure of eight run). Isoki netic dynamometry was performed to evaluate quadriceps and hamstring p eak torque strength. Controls were either age and sex matched individu als or the contralateral knee. Statistical analysis was by Wilcoxon si gned rank test and Spearman rank order correlation coefficient. Result s-JPS was impaired in ACL deficient knees. The mean (SD) errors in rep roducing angles were 9.4 (3.1)degrees and 7.1 (2.3)degrees for the ACL deficient knee and control knee respectively (P<0.0005). There was no improvement in JPS after rehabilitation (9.4 (3.1)degrees and 8.5 (3. 2)degrees before and after rehabilitation respectively, P = 0.14). The re was improvement as ascertained from the questionnaire (on admission 202 (32.1), after rehabilitation 243 (25.4), P<0.0001) and functional activity testing (hop: on admission 148.7 (37.3) cm, after rehabilita tion 169.8 (31.1) cm, P<0.0005; figure of eight: on admission 48.4 (16 .6) seconds, after rehabilitation 41.6 (3.4) seconds, P<0.0001). Quadr iceps strength improved (peak torque on admission 198.5 (58.9) Nm, aft er rehabilitation 210.5 (54.2) Nm, P<0.05), but not hamstring strength (peak torque on admission 130.6 (128.1) Nm, after rehabilitation 135. 5 (27.7) Nm, P = 0.24). JPS did not correlate with the functional acti vity tests (hop and figure of eight run), the responses to the questio nnaire, or strength. There was no correlation between the responses to the questionnaire and functional activity tests or muscle strength. C onclusions-JPS was impaired in ACL deficient knees. Although knee stab ility improved with exercise therapy, there was no improvement in JPS. The role of JPS in the stability of ACL deficient knees remains uncle ar.