Femoral pinless length and offset measurements during computer-assisted, minimally invasive total hip arthroplasty.

We asked whether the intraoperative assessment of leg length (LL) and offset (OS) change would be accurate using a novel pinless femoral reference system during unilateral minimally invasive THA in 50 patients with a mean age of 60 years (48-79). LL and OS change measured at surgery was compared with LL/OS change as measured on magnification-corrected preoperative and postoperative radiographs by two blinded examiners. The radiographic evaluation showed a high inter-rater reliability (r > 0.80 for all assessments). The mean differences (± 95% limits of agreement) between navigation and radiographic measurements on the treated side were +0.4mm (± 3.6) for LL and -1.0 mm (± 3.9) for OS. Femoral pinless navigation technology represents a feasible assistance in THA.