The relative importance of proprioception, ligament laxity and strength on functional performance in the ACL deficient and ACL reconstructed knee

• Main Author: Govett, James Robert
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/4188

The purpose of this study was to determine the relative importance of proprioception, ligament laxity and strength, in the performance of a functional skill, in the conservatively and surgically managed subject following anterior cruciate ligament (ACL) injury. A second purpose of the study was to demonstrate differences in knee proprioception, anterior tibial displacement, quadriceps and hamstring muscle strength, and two functional performance tests among the following three groups: 1) conservatively managed following ACL rupture, 2) surgically managed following ACL rupture, and 3) uninjured controls. The experimental groups consisted of twenty subjects greater than 8 months post ACL injury (conservative group) and twenty subjects greater than 1 year post ACL surgery (surgical group). These groups were compared to twenty control subjects with no history of significant knee joint injury. Joint position sense values were obtained using the protocol of Barrett et al. (1991). Ligament laxity was tested by two anterior tibial displacement measurements using the KT1000 knee ligament arthometer. Quadriceps and hamstring concentric and eccentric peak torque was measured using a KinCom isokinetic dynamometer. Functional performance was measured with the single leg hop for maximum distance (SLHD) and timed six metre single leg hop tests (SLHT). The conservative group scored significantly worse than either of the other groups in proprioceptive inaccuracy, both anterior displacement tests (134N and maximum manual test) and both functional hop tests (SLHD and SLHT). The surgical group was not significantly different from the normal control group in either proprioceptive function or functional hop testing. The surgical group had an excellent post surgical outcome in anterior displacement tests (2.1mm), while the conservative group had a poor result (5.5mm) with the maximum manual test. There were no significant differences among groups in any of the strength measurements. Regressional analyses revealed that concentric quadriceps peak torque had a significant effect on single leg hop for maximum distance performance for all three groups. Proprioceptive acuity and anterior tibial displacement had no significant effect on SLHD in any of the three groups.