Patient-Specific Instrumentation for Total Knee Arthroplasty: A Review
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.
Section snippets
Surgical technique
When using patient-specific guides for total knee arthroplasty, the procedure begins with the preoperative imaging. Depending on the system being used, the patient undergoes any combination of a CT scan of the knee with limited cuts of the hip and ankle, an MRI of the knee with or without limited cuts of the hip and ankle, and a full-length standing anteroposterior (AP) radiograph. This imaging is then used to create a three-dimensional model of the patient's knee and predetermined anatomic
Improved accuracy
As early as 1977, Lotke and colleagues1 recognized the importance of implant positioning in the success of total knee arthroplasty. In 1994, Ritter and colleagues2 showed that, in a series of more than 400 total knee replacements followed for up to 13 years, there was a statistically significant increase in failure of knees aligned in varus. More recently, Sharkey and colleagues3 showed that approximately 70% of revisions performed within the first 2 years after total knee arthroplasty were
Improved efficiency
Several current issues affecting the current health care landscape have brought increased scrutiny to efficiency in the practice of medicine. Skyrocketing health care costs, especially for the Medicare population, have forced politicians and insurers to consider more closely where health care dollars are being spent and how to spend them more wisely. Further, decreasing reimbursement to surgeons and hospitals has had the dual effect of requiring all parties to increase surgical volume while
Future directions
There does not seem to be a clear answer as to the broad applicability of this technology. Further study, especially in the form of randomized controlled trials, is needed to further evaluate this new and promising technology. Further, longer term follow-up of these patients is needed to see whether the proposed benefits of improved alignment and a decrease in surgical outliers will lead to increased implant survival and a decreased revision rate. Also, several studies have highlighted a
Summary
Total knee arthroplasty is one of the most predictably successful procedures in an orthopedic surgeon's armamentarium. Surgeons continuously strive for improvements that can ensure that patients have the best chance for an optimal outcome. New technology must be continuously developed, and, once developed, should be studied appropriately to ensure that it provides maximal benefit to the patient, the surgeon, and the overall health care system. Patient-specific instrumentation is a new
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Cited by (55)
The efficacy of patient specific instrumentation (PSI) in total hip arthroplasty (THA): A systematic review and meta-analysis
2022, Journal of OrthopaedicsCitation Excerpt :The role of the PSI is to help guide the physical positioning of the components during hip arthroplasty.9,12 PSI uses a preoperative CT or MRI to create a 3D patient model that can then be used to make a patient-specific guide for prosthesis placement.13,14 It has been reported that the implementation of PSI during THA has increased surgical accuracy of component positioning leading to improved patient outcomes.15
Accuracy of patient-specific instrumentation in total ankle arthroplasty: A comparative study
2019, Foot and Ankle SurgeryComputed Navigation Guidance for Ankle Replacement in the Setting of Ankle Deformity
2018, Clinics in Podiatric Medicine and SurgeryCitation Excerpt :The use of preoperative imaging-derived patient-specific instrumentation1 is not a new concept in total joint arthroplasty. It has been used in both total knee and hip arthroplasty to improve accuracy of implant alignment and reduce operative times.2–6 More recently, this technology has been implemented for use in total ankle replacement (TAR).
CT-based TruMatch® Personal Solutions for knee replacement Surgery … Does it really match?
2020, Journal of OrthopaedicsCitation Excerpt :While intraoperative computed-assisted navigation purportedly helps surgeons to position and orientate replacement components more accurately, they are also known to have significant drawbacks of increased operative time and higher cost. Patient-specific templates, however, appear to be able to increase alignment while decreasing operative time, increasing patient throughput, decreasing instrumentation, reducing risk of fat embolism and intraoperative bleeding due to intramedullary canal reaming, decreasing tissue loss, shortening recovery, reducing post-operative pain and decreasing incidence of infection.4,6 In view of the benefits, patient-specific templating has been widely popular, with DePuy Orthopedics selling 6000 TruMatch® Patient Specific Instruments in 8 months since its introduction in August 2011, with its sales continuing to rise.4
Influence of instrumentation on the surgical time to implant a total knee prosthesis
2019, Revista Espanola de Cirugia Ortopedica y Traumatologia
Research funding sources: Dr Ast, Stryker Orthopedics; Dr Nam, None; Dr Haas, Smith & Nephew.
Conflict of interest: Dr Ast, None; Dr Nam, None; Dr Haas, Royalties and paid consultant for Smith & Nephew.