Alignment of the prosthesis is one of the most significant factors that affect the long-term clinical outcome following total knee arthroplasty (TKA). There is conflicting evidence whether patient-specific instrumentation (PSI) for TKA improves the component position compared to standard instrumentation. This study aimed to compare the rotational alignment of the femoral and tibial components in TKA patients when performed with either conventional or PSI. Sixty patients with primary knee osteoarthritis were randomly divided into two groups treated surgically with TKA: one with conventional instrumentation and the other with the Visionaire PSI system (Smith and Nephew, Memphis, TN). Computerized tomography (CT) and X-ray imaging were performed preoperatively and 12 weeks after surgery. The rotational alignment of the femoral and tibial component in all patients was assessed postsurgically using CT imaging according to the Berger protocol. Both groups were clinically assessed in a blinded fashion using the Knee Society Score (KSS) and a visual analog scale (VAS). Fifty-eight patients were prospectively assessed. The mean postsurgical follow-up was 3.0 ± 0.4 months. CT images did not reveal any significant improvement in the rotational alignment of the implant components between the groups. X-rays revealed a significant improvement in the deviation from the optimal alignment range of the femoral component in the coronal plane in both groups. Patients operated with Visionaire PSI assistance had poorer functional outcomes. We conclude that there were no improvements in clinical outcomes or knee component alignment in patients treated with PSI compared with those treated with standard instruments. In addition, clinical and functional assessment showed inferior results in terms of KSS and VAS scores at the midterm follow-up in patients treated with PSI.
Keywords: Computerized tomography; Femoral component rotation; Knee arthroplasty; Patient-specific instrumentation; Rotational alignment; Tibia.