Abstract
Purpose: Mobile bearing total knee arthroplasty (MBTKA) has been complicated by bearing spinout and dislocation. Balancing the flexion and extension gaps is a basic principle of knee reconstruction, but is often achieved in a haphazard manner. This balance is critical to prevent bearing spinout and dislocation. A surgical technique is presented which actively balances flexion and extension gaps, and avoids spinout and dislocation in MBTKA.
Methods: Between February, 2002 and May, 2004 , 180 primary MBTKAs were performed, utilizing the PFC ∑RP (DePuy, Warsaw, Indiana, USA) system with a PS femoral component. The surgical technique consisted of distal femur and proximal tibia resection, followed by ligament balancing and measurement of the extension gap utilizing laminar spreaders. With laminar spreaders placed in the knee at 90 degrees of flexion, an AP cutting block with free rotation and AP translation, attached to an intramedullary rod was positioned on the distal femur in order to create a symmetric flexion gap matching the thickness of the previously established extension gap. After AP resections, gap balance was verified using spacer blocks. Preparation of the bony surfaces to accept the prostheses was completed in a standard fashion.
Results: No bearing spinout or dislocation, or instability has occurred.
Conclusions: Meticulous surgical technique directed toward strict balance of the flexion and extension gaps prevents bearing spinout and dislocation in MBTKA, and is critical to the success of this technology which offers the potential long-term benefits of lower wear, soft tissue load sharing and improved overall knee mechanics.
The abstracts were prepared by Ms Orah Naor. Correspondence should be addressed to Israel Orthopaedic Association at PO Box 7845, Haifa 31074, Israel.
