The reversed gap technique produces anatomical alignment with less midflexion instability in total knee arthroplasty: a prospective randomized trial
Matziolis, G., Brodt, S., Windisch, C. et al.Knee
Purpose
No surgical technique is capable of controlling the stability of the joint in midflexion. The purpose of the present study was to present and evaluate a surgical technique that aims to reduce the need for soft-tissue release and optimize stability in midflexion.
Methods
Sixty knee joints were included in this prospective randomized study. Surgery was performed either according to a classical gap (GT) technique or using the reversed gap (RG) technique. In the RG, the femoral component was positioned parallel to the surgical transepicondylar axis using a preoperative MRI and a navigation system. The frontal alignment of the tibia was then selected to produce a symmetric flexion gap. Then, the frontal alignment of the femoral component was adjusted to produce a symmetric extension gap. Soft-tissue release was defined to be extensive if more than two steps or stabilizing structures were involved. Joint stability was measured at different flexion angles (−5° to 120°) using a gap tensioning device and the trial femoral implant.
Results
In the GT group, 16 knee joints (53 %) showed an instability of more than 2 mm at 5°, 30° or 60°, compared with 8 knee joints (27 %) in the RG group (p = 0.035). The RG did not lead to a reduction in the number of soft-tissue releases, but they were less extensive.
Conclusion
RG reduced midflexion instability and the number of extensive soft-tissue releases. It may simplify the operation by reducing the extent of soft-tissue releases and avoid instability-related problems of knee arthroplasty. Nevertheless, it should only be performed under controlled conditions until long-term clinical data are available.
Level of evidence
I.
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