Distribution of prostheses position after primary total knee arthroplasty on dominant and non-dominant sides

Abstract Background To investigate the changes of prosthesis position after primary total knee arthroplasty (TKA) on the dominant and non-dominant sides. Methods A retrospective analysis was made of 132 patients (148 knees) who underwent primary TKA from December 2016 to December 2018 in our hospital. The patients were divided into dominant group (right side) and non-dominant group (left side) according to the position of the three right-handed surgeons. Total operation time, posterior distal femur angle (PDFA), posterior proximal tibia angle (PPTA), malposition rate of femoral prostheses in sagittal, postoperative hip-knee-ankle angle (HKA), mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA) were compared between the two groups. Results The mean total operation time was in dominant group was 111.8(111.8±26.9) and in non-dominant group was 113.7(113.7±26.1) (P>0.05). Postoperative sagittal alignment, the mean PDFA was 90.2(90.2°±3.3°) in dominant group and 88.8(88.8°±3.6°) in non-dominant group (P<0.05). The mean PPTA was 84.8(84.8°±2.8°) in dominant group and 85.4(85.4°±3.7°) in non-dominant group (P>0.05). The incidence of malposition of sagittal femoral prosthesis in dominant group was 6/76 (7.9%) and that in non-dominant was 15/72 (20.8%). There was a significant difference between the two groups (χ2=5.083，P=0.024). Postoperative coronal alignment, the mean angle of components placement was 2.1°±4.2° for HKA, 88.7°±2.7° for mLDFA, 89.5°±2.7° for mMPTA in dominant group and 1.6°±4.1° for HKA, 89.0°±2.8° for mLDFA, 89.9°±2.7° for mMPTA in non-dominant group, respectively. There were no significant difference between the two groups (t=0.804 P=0.423, t=-0.564 P= 0.574, t=-1.011 P= 0.314). Conclusion Our study suggests that surgeon handedness is likely to be one of factors that affect the sagittal placement of femoral component. Orthopaedic surgeons should be aware of the potential problems and consider taking extra precautions to mitigate the risk before performing surgery.