Abstract
Background
Coronal malalignment has been proposed as a risk factor for mechanical failure after total knee arthroplasty (TKA). In response to these concerns, technologies that provide intraoperative feedback to the surgeon about component positioning have been developed with the goal of reducing rates of coronal plane malalignment and improving TKA longevity. Imageless hand-held portable accelerometer technology has been developed to address some the limitations associated with other computer assisted navigation devices including line-of-sight problems, preoperative imaging requirements, extra pin sites, up-font capital expenditures, and learning curve. The purpose of this study was to compare the accuracy and precision of a hand-held portable navigation system versus conventional instrumentation for tibial and femoral resections in TKA.
Methods
This study was a single-surgeon, retrospective cohort study. Consecutive patients undergoing TKA were divided into three groups: 1) tibial and femoral resections performed with conventional intra- and extramedullary resection guides (CON group; N=84), 2) a hand-held portable navigation system (KneeAlign, OrthoAlign Inc, Aliso Viejo, CA) for tibial resection only (TIBIA group; N=78), and 3) navigation for both tibial and distal femoral resections (BOTH group; N=80). Postoperative coronal alignment of the distal femoral and proximal tibial resection were measured based on the anatomic axis from standing AP radiographs and compared between the three groups for both precision and accuracy. Malalignment was considered to be greater than 3° varus/valgus from expected resection angle.
Results
Preoperative age, sex, and knee axis alignment were similar between the three groups. Mean postoperative alignment of the distal femoral resection, proximal tibial resection, and knee axis did not differ between groups (Figure 1). Increased frequencies of malalignment (±3° varus/valgus) of the femoral resection (24% CON versus 5% TIBIA and 8% BOTH; p<0.001) and knee axis (31% CON versus 8% TIBIA and 6% BOTH; p<0.001) were observed with conventional resection guides compared to both navigation groups.
Conclusion
Use of a hand-held portable navigation system improved precision of the distal femoral resection and overall anatomical knee alignment after TKA.
