Measured Resection Versus Gap Balancing for Total Knee Arthroplasty

Abstract

The number of TKAs performed in the United States is expected to increase substantially in the next two decades [6]. Additionally, surgeons are performing TKAs in younger and more active patients. While many articles discuss the importance of radiographic alignment, soft-tissue balancing is essential to a successful TKA. There remains great controversy in how surgeons obtain correct alignment and soft-tissue tensioning. Some surgeons utilize a measured resection technique, while other surgeons favor a gap-balancing technique. As such, I have invited two internationally known orthopaedic surgeons to discuss these two approaches, both of which seek to achieve the same general goal — a well-aligned and well-balanced TKA. Bryan D. Springer MD is an attending joint replacement surgeon at the OrthoCarolina Hip and Knee Center in Charlotte, NC, USA, and a member of The Knee Society. Dr. Springer is the recipient of numerous Knee Society Awards, and has extensive experience with the gap-balancing technique. Sebastien Parratte MD, PhD is an attending joint replacement surgeon and assistant professor of orthopedic surgery at the University Hospital of Marseille in Marseille, France. Dr. Parratte likewise has received numerous Knee Society and Hip Society Awards, and has considerable experience with the measured resection technique. Matthew P. Abdel MD:What do you each see as the advantages of the gap-balancing or measured resection techniques, in terms of achieving ligament balance? Bryan D. Springer MD: Instability following TKA remains one of the most common modes of early failure. The gap-balancing technique is based on the progressive release of ligaments to create equal and symmetric flexion and extension gaps. It is imperative that one understands what structures affect extension, flexion, and both in order to create proper balance. One of the fundamental differences between the gap-balancing technique and measured resection technique lies in setting the rotation of the femoral component to achieve a symmetric flexion gap. Measured resection relies on arbitrary bony landmarks (surgical transepicondylar axis, posterior condylar axis, and anteroposterior (AP) axis of the femur) in order to set rotation. While bony landmarks may occasionally provide accurate rotation of the femoral component, one major disadvantage is the surgeon’s inability to accurately and reproducibly find them intraoperatively. Research has suggested there is wide variability in femoral component rotation when using bony landmarks, which leads to asymmetry of the flexion space and condylar lift off (Fig. 1) in flexion [3]. Open in a separate window Fig. 1 This schematic depicts condylar lift off that occurs when there is asymmetry of the flexion space. Published courtesy of Bryan D. Springer MD.