Patient-Specific Cutting Blocks

Abstract

The numbers and costs of revision total knee arthroplasties are increasing and are projected to represent a significant burden to the health care system (Fig. 1).1 Moreover, the epidemiology of the revisions being performed is troublesome. A significant proportion of revisions are performed within the first 5 years of the index primary arthroplasty, and an estimated 70% of revisions performed within the first 2 years of the index arthroplasty are related to surgical technique.2 There is, therefore, a compelling need to assure that primary TKA procedures performed by orthopedic surgeons of all ranges of experience are carried out accurately and reproducibly. The goals of computer-assisted total knee surgery are to increase the accuracy with which each step of the surgical procedure is performed, reduce the frequency and magnitude of alignment outliers, and produce a balanced, stable knee in flexion and extension. Although an accurate and helpful tool in the hands of experienced knee arthroplasty surgeons, computer navigation has not increased the accuracy with which total knee replacements are performed by inexperienced surgeons or surgeons who perform knee arthroplasties infrequently. The use of computer navigation requires a clear understanding of the goals of each step of the TKA procedure. There is a significant learning curve associated with the use of navigation. Computer-assisted surgical techniques use expensive and cumbersome tools that add complexity to standard TKA instrumentation. Patient-specific instrumentation (PSI) is being proposed as an alternative to navigation for the performance of TKA. The suggested advantages of PSI are as follows: (1) accuracy; (2) short learning curve; (3) adaptable to familiar instrumentation; (4) operating room efficiency; and (5) reduced instrumentation. My interest in PSI technology arose from the idea that if its use by nonarthroplasty surgeons and by surgeons who perform TKA infrequently improved the accuracy with which the procedure was performed and reduced the occurrence of outliers, then the reduction in cost that was associated with improvements in accuracy (eg, fewer revi-