gms | German Medical Science

Objectives: Combined Posterior cruciate ligament (PCL) injury usually results in a substantial posterior instability of the knee joint. PCL insufficiency does not only modify movement patterns of the lower limb, but also influences muscle activation and hence results in a movement strategy that could compensate for pain and joint instability. By developing a novel technique to allow assessment of tibio-femoral kinematics, this study aimed to define the role of passive joint stability on active tibio-femoral kinematics during walking of patients after successful PCL reconstruction with an average follow up of 90 months

Methods: Using motion capture, together with combinations of advanced techniques for assessing skeletal kinematics (SARA, SCoRE, OCST), a novel non-invasive approach to evaluate dynamic tibio-femoral motion was tested in 34 PCL reconstructed subjects (at least 5 years after reconstruction, with no pathologic history at the contralateral side) and 10 healthy subjects with no pathologic history at both limbs. The passive (stress X-rays; Telos-device) and active tibio-femoral joint stability was then examined in 34 patients after successful isolated or combined PCL reconstruction and compared to their healthy contralateral limbs. After verification using multi-factorial ANOVA analyses that residual PCL deficiency has an effect on A-P translation, a post-hoc test was applied to determine the magnitude of the difference in A-P translation between PCL reconstructed and healthy (contralateral) knees

Results and Conclusion: In all subjects, the configurations of the knee flexion-extension, varus / valgus, internal-external rotation angle and moment curves were all maintained. When compared to the healthy control group, the reconstructed sides showed significantly reduced peak flexion angles and reduced peak external rotation angles (p<0.05).

During the gait cycle, the patients also showed reduced flexion angles, especially during the swing phase (68-96% of gait cycle). The reduced external rotation angles were more apparent, with reduced external rotation in loading phases and also the swing phases in these three different activities (Table 1 [Tab. 1]).

We showed that in PCL deficient knees, the symptom of subjective instability during stair ascent and descent is related to dynamic knee dysfunction as represented by reduction in knee flexion angle, external flexion moment and posterior force on the tibia in early stance phase. It appears that the relation of altered kinematics and clinical parameters such as knee laxity and muscle strength is not as consistent as expected. The characteristic knee mechanics appear to be related to disability and subjective symptoms during activities in PCL deficient patients.