Gap balancing versus measured resection technique for total knee arthroplasty

Abstract

Multiple differing surgical techniques are currently utilized to perform total knee arthroplasty (TKA). We compared knee arthroplasties performed using either a measured resection or gap balancing technique to determine if either operative technique provides superior coronal plane stability as measured by assessment of the incidence and magnitude of femoral condylar lift-off. We performed 40 TKA using a measured resection technique (20 PCL-retaining and 20 PCL-substituting) and 20 PCL-substituting TKA were implanted using gap balancing. All subjects were analyzed fluoroscopically while performing a deep knee bend. The incidence of coronal instability (femoral condylar lift-off) was then determined using a 3-D model fitting technique. The incidence of lift-off greater than 0.75 mm was 80% (maximum, 2.9 mm) and 70% (maximum, 2.5 mm) for the PCL-retaining and substituting TKA groups performed using measured resection versus 35% (maximum, 0.88 mm) for the gap-balanced group. Lift-off greater than 1 mm occurred in 60% and 45% of the PCL-retaining and -substituting TKA using measured resection versus none in the gap-balanced group. Rotation of the femoral component using a gap balancing technique resulted in better coronal stability which we suggest will improve functional performance and reduce polyethylene wear.

Fig. 1

Femoral component rotation was determined using a measured resection technique.

Fig. 2

A femoral component is positioned using a gap-balancing technique. (Reprinted with permission from SLACK, Inc. from Dennis DA. Measured resection: an outdated technique in total knee arthroplasty. Orthopedics. 2008;31:940, 943–944.)

Fig. 3

Frontal plane analysis of a 3-D model was used to determine the presence of femoral condylar lift-off.