Validation of imageless navigation in total knee arthroplasty using a postoperative radiographic approach

The integration of computer-assisted navigation systems (CASs) in total knee arthroplasty (TKA) procedures has gained popularity in recent years. However, additional validation of the accuracy of CAS feedback is necessary. We used short-length and full-length postoperative radiographs to quantify the differences between alignment parameters measured by a novel imageless CAS and alignment outcomes as evidenced on postoperative radiographs.

A retrospective analysis was conducted on prospectively collected data from a cohort of patients undergoing navigated primary TKA. Fifty-eight patients had met inclusion criteria, and intraoperative CAS measurements were obtained from device recordings. Alignment parameters were measured digitally and included femorotibial angle on short-length films and hip-knee-ankle axis, mechanical lateral distal femoral angle (mLDFA), and mechanical medial proximal tibial angle (mMPTA) on full-length films. These were compared between CAS and radiograph measurements using a 2-tailed t test.

The mean mLDFA measured by the CAS was 0.7° ± 1.1°, compared with 1.3° ± 1.4° as measured on full-body radiographs (P = .1). The mean mMPTA measured by the CAS was 0.2° ± 1.0°, compared with 0.9° ± 1.4° as measured on full-body radiographs (P = .06). On average, radiograph and CAS measurements differed by 0.5° ± 1.5° for mLDFA and 0.7° ± 1.5° for mMPTA. The average postoperative hip-knee-ankle axis was 177.6° ± 2.1°, and the average femorotibial angle was 176.0° ± 9.6° as measured on radiographs.

No significant differences in either average or individual measured values for mLDFA or mMPTA were observed between the intraoperative CAS measurements and alignment outcomes postoperatively. Our data highlight the clinical utility of CASs to accurately achieve intended TKA alignment objectives.