| Summary: | 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.
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