Assessing Pelvic Tilt in Patients Undergoing Total Hip Arthroplasty Using Sensor Technology

Background: The purpose of our study was to assess the accuracy of a commercially available wearable sensor in replicating pelvic tilt movement in both the sitting and standing position in patients before total hip arthroplasty. Methods: This prospective study evaluated patients undergoing a primary unilateral total hip arthroplasty by a single surgeon. Patients were excluded if they had a body mass index (BMI) greater than 40 kg/m2. Two sensors were adhered directly to patients’ skin at S2 and T12. The S2 angle was recorded on the sensor at maximum flexion and extension angles and compared with pelvic tilt measurements on both sitting and standing radiographs. The primary outcomes recorded were patients’ pelvic tilts measured using radiographs (PT-RAD) and sensors (PT-SEN), with Pearson correlation coefficients and intraclass correlation coefficients (ICCs) calculated. Results: Sixty-one patients (35 males and 26 females) with an average age of 61.5 ± 8.5 years and BMI of 26.9 ± 4.1 kg/m2 were analyzed. The mean prestanding PT-RAD and PT-SEN were 1.5 ± 8.3 and 1.0 ± 8.1, respectively, with an ICC of 0.98 (95% confidence interval, 0.96-0.99). The mean presitting PT-RAD and PT-SEN were -21.9 ± 12.5 and -20.9 ± 11.7, respectively, with an ICC of 0.97 (95% confidence interval, 0.95-0.98). The multiple R2 was 0.95 for the prestanding and presitting comparisons. The R2 for all comparisons between PT-RAD and PT-SEN was >0.85, regardless of BMI or sex. Conclusions: Although the use of wearable technology may have limitations, based on our results, a wearable sensor is accurate in replicating pelvic tilt movement.