Computer-Assisted Total Knee Arthroplasty Using Patient-Specific Templates: the Custom-made Cutting Guides

Abstract

Introduction The success of TKA is dependent on surgical techniques [7, 8, 34] that require accuracy and reproducibility. Current surgical techniques rely on plain radiographs for preoperative planning and standardized conventional instrumentation (CI) systems for performing the procedure. Plain radiographs have limited accuracy [1, 14, 17, 21, 22, 25, 28, 29]. Ten degrees of knee flexion and 20o of external to 25o of internal rotation can cause significant differences in knee alignment measurements [25]. Conventional instrumentation systems have been reported to have limitations that affect the ultimate accuracy of surgery, especially bone cutting and implant alignment [4, 18, 23, 35]. In addition, CI systems are based on average bone geometry, which may vary widely between patients. Nagamine, Miura et al. (2000) reported several anatomical variations in 133 Japanese patients with knee osteoarthritis (OA). Other authors [36, 37] reported that significant mal-alignment errors (>3o) resulted from using extra-medullary and intra-medullary (IM) rods. The accuracy of using CI for sizing is also questionable [15]. Conventional instrumentation systems are relatively complex tools with numerous jigs and fixtures. Their assembly is time consuming and may lead to errors. Their repeated use carries a theoretical risk of contamination. The use of alignment guides involves the violation of IM canals. This can lead to a higher risk of bleeding [3, 19], infection [26, 27], fat embolism [20] and fractures [5]. Each TKA prosthesis has its own instrumentation. In the United Kingdom, there are more than 30 TKA prostheses and it is common to have different prostheses used in the same hospital [24]. This may overload hospital inventory, sterilization services, nurses’ learning curves, and operating room time. Although conventional surgical instrumentation have been repeatedly modified, it appears that further refinements are unlikely to overcome their inherent drawbacks such as the multiplicity of instruments and the medullary canal perforation.