ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION AND JOINT DYNAMICS DURING STAIR CLIMBING

Athletes with anterior cruciate ligament (ACL) deficiencies exert decr eased knee extension moments during level walking (quadriceps avoidanc e gait), and yet within a few months of ACL reconstruction they are of ten expected to return to competitive sport. To investigate this issue further, 10 normal subjects and seven ACL deficient patients were eva luated both pre-and post-operatively (mean follow-up of 6 months), and each performed multiple trials ascending a staircase which consisted of three steps. Bilateral joint angles, moments, powers, and work were measured and the data were ensemble averaged and statistically analyz ed (repeated measures ANOVA with significance level set at 0.05). Ante rior-posterior knee laxity decreased significantly (from 7.9 mm to 5.8 mm) while subjective knee function also improved following ACL recons truction (knee score increased from 70.4 to 88.5). Pre-operatively, th ere were no statistically significant differences in biomechanical par ameters between the patients' ACL-deficient and intact sides and the n ormal subjects. Post-operatively, however, statistically significant r eductions were seen for the peak moment (91.9 vs 22.5 Nm), power (181 vs 84 W), and work performed (28.0 vs -5.6 J) at the injured knee, whi ch was also the knee from which the patellar tendon graft had been har vested. These reductions were accommodated by significant increases in excursion, moment, and power at the contralateral ankle joint. The re sults indicate that while the ACL reconstructions were successful in r estoring anterior-posterior knee stability, the decrease in knee power and work performed post-operatively by the injured (i.e., donor) knee suggests that donor site morbidity may need to be critically evaluate d over a long-term period.