COMPUTER-ASSISTED SURGERY IN TOTAL KNEE ARTHROPLASTY: EXPERIENCE WITH THE VECTORVISION® AND CITM NAVIGATION SYSTEM FOR MOBILE BEARING TKA

Abstract

Introduction: Computer-assisted TKA improves alignment accuracy; however few articles cite any clinical benefit over conventional TKA. The author’s experience and outcomes with CAS for TKA including ligament balancing with a spring loaded tensioning device is reported.

Methods: This is a retrospective review of prospectively collected data on 1005 TKAs (975 had OA) with 464 cases using Depuy^® LCS^® CompleteTM Rotating Platform and 474 cases using Depuy^® P.F.C^® SigmaTM Rotating Platform. Seventy-six were conventional TKAs and 929 were CAS TKAs. Average follow up was 17 months. Outcome variables included radiographic alignment, Knee Society Scores, and complications.

Results: Eighty-eight percent of CAS TKAs were placed within three degrees of neutral mechanical axis. Eighty-one percent were placed within three degrees of optimal sagittal tibial component angle. Ninety-two percent were placed within three degrees of optimal coronal tibial component angle.

Mean pain score improved 39.4 points, Knee Score improved 47.8 points, and the functional component improved 17.1 points. The pain score improvement for CAS was 39.2 compared to 33.0 for conventional knees (p< 0.002). The Knee Score improvement for CAS was 48.3 compared to 41.4 for conventional knees (p< 0.013). The functional component improvement was not significant between CAS and conventional TKA. When CAS is utilized along with the spring loaded tensioning device for ligament balancing, manipulation rates dropped to 7% (p< 0.01). There were a total of thirteen infections, three deep infections (0.3%) and ten superficial infections (1%). There were no fractures from the pin sites, and no patients were revised for instability.

Conclusion: Our series showed a statistically significant improvement in pain and Knee Society Scores compared with conventional TKA. In addition, CAS resulted in excellent radiographic alignment and well balanced knees with the spring loaded tensioning device. Furthermore, improved radiographic alignment is likely to increase implant survivorship and provide further cost savings. With continued use of CAS, long term studies may show significant beneficial clinical effects.