Is gap balancing superior to measured resection technique in total knee arthroplasty? A meta-analysis

Measured resection and gap balancing are two distinct methods for proper femoral component alignment in total knee arthroplasty. Decision-making between the two techniques is controversial. The aim of this systematic review and meta-analysis was to compare measured resection and gap balancing with regard to the radiological and clinical benefits, and to examine whether this change the conclusions from previous trails.

A systematic literature search of the medical literature from January 1990 to February 2015 was performed. We selected six randomized controlled trials and five prospective cohort studies comparing gap balancing and measured resection in patients undergoing primary total knee arthroplasty. Data from included studies were pooled with use of fixed-effects and random-effects models with standard mean differences and risk ratios for continuous and dichotomous variables, respectively. Heterogeneity across studies was assessed with calculation of the I² statistic.

A total of 857 knees from 11 trials were included. Four hundred and forty-one knees were treated with gap balancing and 416 were treated with measured resection. In contrast to previous studies, we found that gap balancing demonstrated better patient-reported outcomes with regard to Knee Society score for pain (WMD 2.75, p = 0.004) and Knee Society score for function (WMD 5.47, p < 0.0001) at two-year follow-up. Gap balancing showed more precise limb alignment in terms of post-operative value of mechanical axis (WMD 0.40°, p = 0.01) and risk of mechanical alignment outliers (RR 0.350, p < 0.0001). However, gap balancing was associated with more joint line elevation (WMD 1.27 mm, p < 0.0001) and longer operative time (WMD 16.18 min, p < 0.0001). No significant difference was observed in rotation of the femoral component (p = 0.07).

The meta-analysis demonstrated that gap balancing was able to achieve more precise coronal alignment with better short-term patient-reported outcomes compared with measured resection. Measured resection was more desirable than gap balancing with regard to restoration of the joint line and operative time. Comparable femoral rotational alignment was observed.