Abstract
Introduction:
One of the primary goals in total knee arthroplasty (TKA) is restoration of the mechanical alignment. The accuracy of conventional mechanical alignment guides and computer-assisted navigation systems has been extensively studied. The purpose of this study is to assess the accuracy of a hand-held accelerometer-based navigation system for TKA.
Methods:
Fifty three patients undergoing TKA utilizing the KneeAlign system (OrthAlign Inc, Aliso Viejo, CA) (Figure 1) were performed by two surgeons. Intraoperative data including tourniquet time, device assembly time, and resection times were recorded. Target alignment goals were 0° femoral, tibial, and overall mechanical coronal alignment and 3° femoral flexion and posterior tibial slope. Coronal/sagittal alignment of the implant and the mechanical axis were measured by two independent observers on full length (54 inch) postoperative hip to ankle radiographs.
Results:
Average femoral coronal alignment was 0.29° varus ± 2.2° with 13% of patients exceeding 3° of varus/valgus. Average tibial coronal alignment was 0.25° valgus ± 1.4° with 4% of patients exceeding 3° of varus/valgus. Average femoral flexion angle was 87.2° and the average tibial posterior slope was 2.8° ± 1.8 °. Average postoperative mechanical axis was 0.2° varus ± 2.1°with 13% of patients exceeding 3° of varus/valgus (Figure 2). The average time to completion of femoral and tibial resection was 4.8 and 4.6 minutes, respectively, with an overall tourniquet time of 62 minutes.
Conclusion:
The KneeAlign system was accurate for reestablishing the mechanical axis and the femoral and tibial component alignment in TKA without increasing surgical time. Accuracy was better for tibial than femoral resection, but overall superior to mechanical alignment guides and comparable to computer-assisted navigation.
