Comparison of alignment between computer assisted surgery and personal specific instrumentation in total knee arthroplasty

Abstract

Objective: To explore the differences of alignment and operative time between computer assisted surgery (CAS) and personal specific instrumentation (PSI) in total knee arthroplasty (TKA). Methods: Patients with knee osteoarthritis who underwent unilateral primary TKA in Peking University Third Hospital from June 2019 to April 2021 were enrolled in this prospective study and were randomly divided into CAS group and PSI group with random number table. The differences in preoperative general data, operative time, preoperative and postoperative alignment between the two groups were studied. Results: A total of 80 patients were enrolled in this study, including 40 patients in the CAS group with an average age of (68±6) years (male/female, 6/34 cases) and 40 patients in the PSI group with an average age of (69±6) years (male/female, 5/35 cases). There was no significant differences in gender, age, height, weight, body mass index, surgical side, preoperative hip-knee-ankle (HKA) angle, and preoperative HKA angle deviation between the two groups (all P>0.05). The accuracy of sagittal femoral component angle (sFCA) (1.7°±1.2° vs 2.5°±1.4°, P<0.05) and sagittal tibial component angle (sTCA) (1.2°±0.9° vs 2.3°±1.8°, P<0.01) of the CAS group were both smaller than those in the PSI group, but there was no significant difference in the accuracy of postoperative HKA angle, mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibia angle (mMPTA) between the two groups (all P>0.05). The precision of postoperative HKA angle and sTCA of the CAS group were both smaller than those in the PSI group (2.0°±1.0° vs 2.6°±1.7°, 1.2°±0.9° vs 2.3°±1.8°, both P<0.01), but there was no significant differences in the precision of mLDFA, mMPTA and sFCA between the two groups (all P>0.05). The rate of outliers of postoperative HKA angle (10.0% vs 27.5%, P<0.05), sFCA(5.0% vs 20.0%, P<0.05) and sTCA (2.5% vs 22.5%, P<0.01) of the CAS group were all smaller than those in the PSI group, but there was no significant difference in the rate of outliers of mLDFA and mMPTA between the two groups (both P>0.05). CAS group had significantly longer surgical time than the PSI group ((81±12) min vs (52±8) min, P<0.01). Conclusions: CAS is better than PSI in overall coronal alignment and sagittal position of the prosthesis after TKA. However, CAS requires a longer operation time.