LATEST NEWS

Computer-Navigated Versus Conventional Total Knee Arthroplasty: A Prospective Randomized Trial

Background:
The literature lacks studies that confirm whether the improved radiographic alignment that can be achieved with computer-navigated total knee arthroplasty improves patients’ activities of daily living or the durability of total knee prostheses. The purpose of this study was to determine whether computer-navigated total knee arthroplasty improves the clinical function, alignment, and survivorship of the components.
Methods:
We prospectively compared the results of 520 patients with osteoarthritis who underwent computer-navigated total knee arthroplasty for one knee and conventional total knee arthroplasty for the other. The assignment of the knee to navigation or not was done randomly. There were 452 women (904 knees) and sixty-eight men (136 knees) with a mean age of sixty-eight years (range, forty-nine to eighty-eight years) at the time of the index arthroplasty. The mean follow-up period was 10.8 years (range, ten to twelve years). The patients were assessed clinically and radiographically with the rating system of the Knee Society and with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score at three months, one year, and annually thereafter.
Results:
Total knee scores, knee function scores, pain scores, WOMAC scores, knee motion, and activity scores did not show statistically significant differences between the two groups preoperatively or at the time of the final follow-up. Alignment and the survivorship of the components were not significantly different between the two groups. The Kaplan-Meier survivorship with revision as the end point at 10.8 years was 98.8% (95% confidence interval [CI], 0.96 to 1.00) in the computer-navigated total knee arthroplasty group and 99.2% (95% CI, 0.96 to 1.00) in the conventional total knee arthroplasty group.
Conclusions:
Our data demonstrated no difference in clinical function or alignment and survivorship of the components between the knees that underwent computer-navigated total knee arthroplasty and those that underwent conventional total knee arthroplasty.
Level of Evidence :
Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.
Source:J Bone Joint Surg Am, 2012 Nov 21;94(22):2017-2024

Patient-specific Instruments for Total Knee Arthroplasty

The use of patient-specific instruments for total knee arthroplasty shifts computer navigation for bone landmark registration and implant positioning from the intraoperative to the preoperative setting. Each system requires preoperative MRI or CT, with specifications determined by the instrument anufacturer. The marketed advantages of patient-specific instruments include greater accuracy in coronal alignment with fewer outliers, no need for instrumentation of the intramedullary canal, reduced surgical time, lower hospital costs, and improved clinical outcomes. The few published results of these instruments suggest minimal gains obtained in hospital logistics variables and minimal evidence of improvement in either alignment or patient outcomes. Disadvantages of patient-specific instruments include increased costs for imaging and instrument fabrication as well as increased preoperative time required for surgical planning and reviewing the instrument plans, and the learning curve for the surgeon to work with the engineers and use these instruments intraoperatively. It is also necessary to have a set of standard instruments available in case the patient-specific instruments do not work properly. Additional data are required before deciding whether these instruments should be recommended.
Source: Sept 2013 JAAOS