Introduction

In orthopedics, as in other aspects of medicine, new technology is often introduced with the goal of improving the lives of patients as well as the lives of their physicians. The most successful of these innovations improve simplicity and render treatment more effective, accurate, and efficient. A new technology that promises to achieve these results is patient-specific instrumentation for total knee arthroplasty.

Patient-specific instrumentation involves the use of preoperative advanced imaging techniques, including computed tomography (CT) scan, magnetic resonance imaging (MRI) and full-length radiograph, and rapid prototyping technology to create patient-matched cutting guides that are reverse engineered to reverse glove fit onto the femur and tibia, for use during the bony resections of a total knee replacement. Specific systems allow the surgeon to either cut directly through the custom block or to use a standard cutting block based on the pin placement from the patient-specific guides. This technology determines bony resections, implant rotation, implant position, and implant sizes before surgery with the use of an interactive, computer-based planning tool. During surgery, the surgeon and team are prepared with the proper sizes and do not need to use the standard intramedullary or extramedullary guides. This preparation can reduce the surgical procedure by as many as 21 steps and can reduce the amount of equipment necessary to perform the operation, which not only increases intraoperative efficiency but improves turnover and setup time as well, because fewer trays must be processed or opened before surgery.

This technology was introduced to address several challenges currently facing surgeons who perform total knee replacements. Accuracy of component placement has long been considered as paramount to the success of total knee replacements. Several technological advances have been introduced over time, beginning with the first introduction of cutting blocks, in an attempt to make total knee replacement a more accurate and reproducible procedure. However, the limited accuracy of both intramedullary and extramedullary alignment guides have provided an impetus for newer technology to improve the way most knee replacements are performed. Furthermore, the difficulties associated with the implementation of computer-assisted surgery have renewed focus on the ultimate goal of creating an easily implementable technology to improve accuracy and outcomes of total knee replacement. In addition, the current focus on efficiency in the health care system has forced orthopedic surgeons to reexamine their current methods and look for new ways to improve their efficiency without sacrificing patient care.

These challenges have led both surgeons and manufacturers to seek improved efficiency through the use of patient-specific instrumentation for total knee replacement. This technology may offer solutions including improved surgical accuracy and reproducibility, increased operating room efficiency, and, perhaps, decreased overall costs. Other proposed benefits include a possible decrease in intraoperative blood loss, decreased pain, and elimination of fat emboli because there is no need to violate the femoral canal. Also, fewer required instruments could lead to a reduced potential for intraoperative contamination.