gms | German Medical Science

Objectives: Failure after medial collateral ligament reconstructions (MCLR) has been suggested to be associated with valgus malalignment. Thus, the aim of this study was to analyze the forces on a MCLR relative to the valgus alignment of the knee.

Methods: Eight fresh-frozen human cadaveric knees (72.9 ± 9.5 years) were subjected to dynamic valgus loading using a custom-made kinematics rig at 400 N axial loading. After resection of the superficial medial collateral ligament, a single bundle MCLR with a hamstring tendon autograft was performed. The tibial side of the reconstruction was connected to a custom-made tensioning device connected to a force sensor, which allowed measurement of the forces acting on the reconstruction with an accuracy of ± 0.1 N. A medial opening wedge distal femoral osteotomy was performed and fixed with an external fixator to gradually adjust the alignment in five degree increments: 0° valgus (force vector passing through the center of the tibial spine), 5° valgus (force vector passing through 75% of the distance between the most medial and lateral aspects of the tibial plateau), and 10° valgus (force vector passing through 100% of the distance between the most medial and lateral aspects of the tibial plateau). For each degree of valgus deformity, the resulting forces on the MCLR were captured from 0° to 60° of knee flexion.

Results and conclusion: Irrespective of the degree of knee flexion, increasing valgus malalignment resulted in significantly increased forces on the MCLR compared to neutral alignment (p<.05). Dynamic valgus loading with a valgus malalignment of 5° resulted in a force increase within the MCLR of at least 70%, ranging from 16.2 N to 18.5 N at all flexion angles (p<.05 from 0° to 30°; p<.01 from 45° to 60°). 10° valgus malalignment further increased the forces on the MCLR by at least four times compared to the neutrally aligned knees, ranging from 29.4N to 40.0N at all flexion angles (p<.01 from 0° to 45°, p<.05 at 60°).

Valgus malalignment of the knee caused increased forces on the reconstructed MCL. In cases of chronic medial instabilities accompanied by a valgus deformity ≥5°, a realigning osteotomy should be considered concomitantly to a MCLR to protect the graft and potentially reduce graft failures.