Search

Patient-specific instrumentation (PSI) was developed to improve the accuracy of component positioning through custom cutting blocks constructed based on preoperative 3-dimensional imaging in total knee arthroplasty (TKA). The purpose of this study was to compare the clinical and radiological outcomes between the patients who underwent PSI-assisted TKA or conventional TKA. Sixty-four patients (64 knees) underwent TKA by a single surgeon: 32 patients (32 knees) underwent TKA with PSI, 32 patients (32 knees) underwent TKA with conventional instrumentation. The mean age of the patients was 67.6 years, and the mean follow-up duration is 26.2 months. Patients were evaluated preoperatively and after surgery. The current authors evaluated clinical outcomes including knee range of motion, Hospital for Special Survey scale, Western Ontario and McMaster University Osteoarthritis Index, and Knee Society pain and function scores. The current authors also compared radiological outcomes including mechanical axis and coronal and sagittal alignment. The current authors found no significant differences in any clinical outcomes between the PSI-assisted TKA group and the conventional TKA group. In terms of radiological outcomes, the PSI-assisted TKA group had fewer alignment outliers. The current authors found that PSI-assisted TKA restores limb alignment better than conventional TKA, but PSI does not confer a substantial advantage in early functional outcomes after TKA. Further follow-up is needed to ascertain the long-term impact of these findings. [Orthopedics. 2016; 39(3):S83-S87.]. [ABSTRACT FROM AUTHOR]

Open-wedge high tibial osteotomy (HTO) with navigation provides accurate axial alignment correction in the frontal plane but can cause an unintended increase of the proximal tibial slope. This study examined the plausibility of preserving the original posterior slope of the proximal tibia during navigation-assisted open-wedge HTO. Three-dimensional virtual HTO preserving the original posterior slope was simulated and the opening gaps measured. Forty cases of navigation-assisted open HTO for unicompartmental osteoarthritis were performed maintaining an anterior opening gap measuring 67% of the posterior gap. The posterior slope of the proximal tibia was compared before and after surgery. In virtual surgery, a ratio of 0.67 between the anterior and posterior opening gap was needed to maintain the original slope. In navigation-assisted HTO, the mechanical axis was corrected to 2.9 degrees valgus (range, 0.5 degree-6.2 degrees) with fewer outliers (12.5%), and the posterior slope was maintained. The posterior slope was 7.9 degrees +/- 2.3 degrees preoperatively and 8.3 degrees +/- 2.8 degrees postoperatively (P > .05). The normal tibial posterior slope can be maintained if the anterior opening gap is approximately 67% of the posterior opening gap during the navigation-assisted HTO. [ABSTRACT FROM AUTHOR]

We evaluated the accuracy of navigation systems for measuring the mechanical axis in patients undergoing total knee arthroplasty and in the synthetic bone model. Infrared optical and electromagnetic navigation systems were compared. Both systems were found to be accurate and reproducible in an experimental environment. However, the accuracies of both systems were affected by erroneous registration, and the optical system was found to be more reproducible. In clinical situations, the mean difference was 1.23 degrees, and difference greater than 3 degrees occurred in 15% of clinical trials. These discordances may have been due to ambiguous anatomic landmarks causing registration errors and the possibility of electromagnetic signal interference in the operating room.

This prospective study aimed to compare the clinical and radiologic results achieved using navigation-assisted minimally invasive surgery (NA-MIS) and conventional techniques in 42 patients who underwent bilateral total knee arthroplasty (TKA), with a minimum 1-year follow-up. Patients who underwent NA-MIS TKA showed better Hospital for Special Surgery (HSS) Scores and Western Ontario MacMaster (WOMAC) total scores for up to 6 months postoperatively than patients who underwent conventional TKA, and lower WOMAC pain score for up to 9 months postoperatively. Range of motion (ROM) was comparable in both groups at all times. More patients preferred the NA-MIS procedure to the conventional procedure. Radiologic results for the NA-MIS group showed fewer outliers than did results for the conventional group, but not in mean values.