Abstract
Introduction
Patient specific instruments (PSI) and computer-assisted surgery (CAS) are innovative technologies that offer the potential to improve the accuracy and reproducibility with which a total knee arthroplasty (TKA) is performed. It has not been established whether clinical, functional, or radiographic outcomes between PSI, CAS, and manual TKA differ in the hands of an experienced TKA surgeon. The purpose of this study was to evaluate clinical, functional and radiographic outcomes between TKA performed with PSI, CAS, and manual instruments at short-term follow-up. Our hypothesis was that at early follow-up, we would be unable to elucidate any significant differences between the groups using the most commonly utilized outcomes measures.
Methods
40 PSI, 38 CAS, and 40 manual TKA were performed by a single surgeon. The groups were similar in regards to age, sex, and preoperative diagnosis. The Knee Society Scoring System was used to evaluate patient clinical and functional outcome scores preoperatively and at 1 and 6 months postoperatively. Long-standing AP radiographs were obtained pre and postoperative to evaluate mechanical axis alignment.
Results
PSI, CAS, and manual TKA produced similar interval improvements in clinical and functional outcomes at both 1 and 6-months postoperative. Knee Society Knee scores were on average 88.5, 72.5, and 69.3 for PSI, CAS, and manual TKA at 1 month and 99.4, 83.4, and 84.6 at 6 months postoperative. Knee Society Function scores were on average 65.9, 49.3, and 48.4 for PSI, CAS, and manual TKA at 1 month and 86.3, 66.2, and 61.2 at 6 months postoperative. Although PSI tended to have higher absolute Knee and Function scores at 1 and 6 months postoperative, the interval change from preoperative to postoperative between each group was similar. Postoperative mechanical axis alignment was not significantly different between PSI, CAS, and manual TKA (1.0â�°, 2.0â�°, and −0.2â�°, respectively).
Discussion
This study suggests that in the hands of an experienced arthroplasty surgeon, PSI, CAS and manual TKA produce similar interval improvements in clinical, functional, and radiographic outcomes at short-term follow-up. These results may reflect the ability of an arthroplasty-trained academic surgeon to perform a TKA accurately with multiple technologies. These findings may also represent the lack of sensitivity and inability of commonly utilized evaluation tools, like plain radiographs and the Knee Society Scoring System, to adequately differentiate small differences in outcomes and limb alignment, if differences do indeed exist. Long-term follow-up will help establish whether these TKA technologies continue to demonstrate equivalent clinical and functional interval improvements.
