According to recent estimates, more than 4.7 million Americans are currently living with a prosthetic knee. The incidence of total knee replacement (TKR) increased by 120% from 2000 to 2009, but it has also increased by 188% for patients aged 45 to 64 and by 89% for patients aged 65 to 84. As a result of the growing popularity of TKR, technical advances are of great interest to surgeons and patients alike.
Improvements in Technology
The Omninav surgical navigation system (OMNIlife science, Inc.) is a device that was designed for TKR. It provides computer-guided precision and features bone morphing technology to allow surgeons to build a patient-specific three-dimensional model of the knee in real time. This creates a virtual surgical plan that can be used before making critical bone cuts. Navigation algorithms and adjustable resection guides enable surgeons to reconstruct the mechanical axis of a limb. No preoperative CT or MRI is required.
The technology is complemented by a patented cutting guide, an intelligent robotic tool that automatically positions instruments. This can be helpful to optimize implant alignment. The instrumentation allows for simple, micrometric adjustments that can be made intraoperatively to ensure alignment and balance the knee joint. Real-time assessment of limb alignment and soft tissue can be made at any time during the procedure.
After administration of regional and/or general anesthesia, any preferred surgical approach may be used. Reference markers are pinned onto the tibia and femur; this is then tracked by the computer in a three-dimensional space. Surgeons can then measure specific locations of the exposed knee joint. This approach allows surgeons to get a detailed, accurate three-dimensional model of the knee joint and alignment of the leg.
Aiming for Better Accuracy
The system’s computer determines the size and position of each implant component. Utilizing a robotically aligned cutting guide, the end of the femur can be reshaped with a saw. Subsequently, the tibia can be reshaped in a similar fashion with guidance from a nanoblock cutting guide. Following preparation, surgeons can insert the components into the knee to ensure that the joint is working properly and remove the reference markers. Each patient’s preoperative and postoperative range of motion and alignment are documented in the computer. This method enables surgeons to become more accurate on a consistently reproducible basis.
Most robotic technologies that are being used today for knee resurfacing procedures are only offered for unicompartmental or partial knee replacement. This system is different in that it’s specifically designed for TKR, providing the precision of a robot on even the most significant knee joint deformities. This technology is just one of several emerging procedures for TKR that will further enhance surgeons’ ability to optimize care for patients who need these procedures.
Readings & Resources (click to view)
Bäthis H, Shafizadeh S, Paffrath T, Simanski C, Grifka J, Lüring C. Are computer assisted total knee replacements more accurately placed? A meta-analysis of comparative studies. Orthopaed. 2006;35:1056-1065.
Koulalis D, O’Loughlin P, Kendoff D, Plaskos C, Pearle A. Can a miniature automated guide positioner save time and improve precision in computer-assisted TKA? RCSEng. London, UK. 2009.
Maradit-Kremers H, Crowson CS, Larson D, Jiranek WA, Berry DJ. Prevalence of total hip (THA) and total knee (TKA) arthroplasty in the United States. American Academy of Orthopaedic Surgeons 2014 Annual Meeting (poster).
Odum SM, Troyer JL, Kelly MP, Dedini RD, Bozic KJ. A cost-utility analysis comparing the cost-effectiveness of simultaneous and staged bilateral total knee arthroplasty. J Bone Joint Surg Am. 2013;95:1441-1449.