The Extramedullary Tensor Technique for Unicondylar Knee Arthroplasty

Abstract

The extramedullary (EM) tensor tools and surgical technique were developed to orient cutting guides for the implantation of the M/G unicompartmental prosthesis with greater ease and accuracy and to reduce the surgical morbidity of this limited reconstruction. Unicompartmental knee replacement attempts to reduce pain and improve function by restoring the extremity’s alignment and the joint’s soft tissue balance with the positioning of an implant limited to that compartment. All unicompartmental implants, be they monoblock wafers, mobile bearing devices, or fixed articular prostheses, must effect this restoration to enjoy whatever success they may provide.

Various surgical techniques for their implantation are available. Instrument systems without direct linkage of the femoral and tibial cuts require intuitive estimates. With such a technique, the implant must, in effect, be retrofitted. The cuts are made and then a device of a given volume and width is chosen that best fits the flexion and extension gaps created. Those cuts were not predetermined for a given implant and thus are approximations. Approximations can work well should there be unlimited prosthetic sizes from which to choose.

Adapted from Saenger PL, Minimally invasive surgery for unicondylar knee arthroplasy: The extramedullary approach, in Scuderi GR, Tria AJ, Berger RA (eds.), MIS Techniques in Orthopedics, 2006, with kind permission of Springer Science+Business Media.