Short- to mid-term outcomes of computer navigation assisted total knee arthroplasty using adjusted mechanical alignment compared to mechanical alignment

Abstract Purpose To evaluate efficacy of navigation-assisted total knee arthroplasty (TKA) achieved using adjusted mechanical alignment (aMA) and mechanical alignment (MA) technique. Methods The authors performed a retrospective study enrolled a single-center series of patients who underwent navigation-assisted TKA with aMA (n = 77) and with MA (n = 61) technique. The demographic data was recorded. Functional scores including Hospital for Special Surgery score, Western Ontario and McMaster Universities Osteoarthritis Index score and Forgotten Joint Score-12 were evaluated. In addition, the parameter of resection and soft tissue balance as well as radiographic evaluation was measured and compared between groups. Results The HSS score at 1-month and 6-months postoperatively were significant higher using aMA compared to MA. The postoperative coronal alignment was made with a mean of 1.11° more varus/valgus in the aMA group compared to MA. The femoral prosthesis was positioned in a mean of 2.29° more varus/valgus using aMA compared to MA. The medial extension gap was significantly tighter in the MA group. In addition, the femoral prosthesis in the aMA group was positioned in a mean of 0.77° more external rotation than the MA group. The lateral flexion gap was wider in the aMA group with a mean of 0.71 mm more laxity. Conclusions Both aMA and MA technique in TKA obtained good clinical outcomes. Notably, aMA-TKA grant superior functional scores at 1-month and 6-months follow-up, might due to the preservation of mild constitutional frontal deformity with less release of soft tissue and a biomimetic wider lateral flexion gap was remained.