Clinical and functional comparison of bicondylar sledge prostheses retaining all ligaments and constrained total knee replacement.

Objective: Comparison of different total knee replacements regarding clinical and functional differences with respect to gait and electromyographic analyses.

Design: Retrospective, comparative, clinical and functional study.

Methods: Three groups (control group of 11 healthy subjects, 15 patients with bicondylar sledge prostheses retaining all ligaments (cemented unicondylar prostheses in both the medial and lateral compartment), 15 patients with constrained total knee replacement sacrificing all cruciate and collateral ligaments (cemented total knee prosthesis with intramedullary stems and a large intercondylar tibial post) were compared by clinical evaluation using a number of clinical evaluation scores, a pain scale, surface electromyographic examinations of the lower limb, and gait analysis.

Results: Clinical scores revealed significantly worse results for patients with constrained prostheses. Both patient groups had significantly lower clinical scores compared to the control group. Gait analysis and electromyographic parameters revealed no significant differences between both patient groups. Compared to the control group, patients revealed significantly impaired parameters. Electromyography also demonstrated significant differences between patients and controls: mean electromyographic activities were reduced in vastus medialis and lateralis, semitendinosus, tibialis anterior and gastrocnemius. Peak activities were reduced in all muscles but rectus femoris.

Conclusion: Clinical scores demonstrated significantly better results in bicondylar sledge than in constrained prostheses. Nevertheless, gait and electromyographic analyses did not reveal significant differences.

Relevance: Retaining of ligaments in bicondylar sledge prostheses apparently improved the activities of daily living but is not reflected in gait and electromyographic parameters.