Effects of Surgeon Handedness on the Outcomes of Unicompartmental Knee Arthroplasty: A Single Center's Experience.

Abstract

Surgeon handedness has been widely discussed in operative surgery, and could cause clinical discrepancy. However, few studies have reported the effect of handedness on unicompartmental knee arthroplasty (UKA). Based on our clinical observation and case analysis, we aimed to find out the effects of surgeon handedness on UKA. We retrospectively studied 94 UKA procedures performed by one right-handed surgeon from January 2017 to December 2018 at a single medical center. The cases were divided into two groups by operation side (49 L-UKAs and 45 R-UKAs). Preoperative demographic data were collected. Imaging parameters (femorotibial and hip-knee-ankle angles and tibial-plateau retroversion) and joint function scores (Knee Society Score [KSS] and Oxford Knee Score [OKS]) were recorded. Patients were followed up regularly and Forgotten Joint Score (FJS) was calculated at the last follow-up. All data were compared between the two groups with independent-samples t-test, and paired t-test was used for intragroup comparisons. The average follow-up was 26.7 ± 3.2 months. The average patient age was 63.5 ± 9.0 years and the average body mass index was 26.89 ± 3.43 kg/m2 . There was no significant group difference in any preoperative characteristic. Both the KSS and OKS improved significantly after surgery (p < 0.05). No significant group difference was found between the KSS or OKS at any follow-up visit. The varus or valgus of tibial component was 3.57 ± 1.42° on the left side and 3.19 ± 1.56° on the right side (p=0.45). The varus or valgus of femoral component was 7.81 ± 2.43° in patients undergoing L-UKA and 7.05 ± 2.90° in those undergoing R-UKA (p=0.04). No statistical differences were found in outliers of component orientation on both sides. The femorotibial and hip-knee-ankle angles improved significantly in both groups, and there was no significant group difference in either lower limb alignment or tibial-plateau retroversion. The complication rate was 8.16% (4/49) in the L-UKA group and 6.67% (3/45) in the R-UKA group. There was no correlation between prosthesis orientation and early joint function score. Surgeon handedness may cause a worse prosthetic orientation on femoral side during surgeon's non-dominant UKA, and surgeons should be cautious of bone resection and prosthesis implantation. However, radiographic difference did not bring variations on short-term clinical outcomes or lower limb alignment.