# Inclinometer use in primary total hip arthroplasty does not improve acetabular component positioning: a non-randomized control trial

## TL;DR

Using inclinometers during hip replacement surgery does not significantly improve implant placement accuracy or patient outcomes.

## Contribution

This study provides evidence that intraoperative inclinometers do not improve acetabular component positioning in primary total hip arthroplasty.

## Key findings

- Inclinometer use resulted in a statistically significant but not clinically significant increase in acetabular cup inclination.
- No significant differences were found in anteversion or dislocation rates between inclinometer and control groups.
- Inclinometer measurements did not correlate with postoperative acetabular component inclination.

## Abstract

Total hip arthroplasty (THA) is a common surgical procedure that aims to relieve pain, improve function, and increase mobility in patients with hip joint pathology. One of the most challenging aspects of THA is to determine the correct angle of the acetabular component’s placement. Intraoperative inclinometers have emerged as a promising tool to obtain accurate measurements of the acetabular component’s inclination. The primary objective of this study was to evaluate the accuracy and efficacy of using intraoperative inclinometers for THA.

This non-randomized control trial evaluated patients undergoing primary THA. Patients in the inclinometer group had an inclinometer used intraoperatively to measure acetabular component inclination, and patients in the control group had no inclinometer. Inclination and anteversion of the acetabular component were measured on postoperative radiographs.

A total of 223 patients were included in the study. The mean inclination angle of the acetabular cup was significantly higher in the inclinometer group (43.9° vs. 41.5°, P < 0.001). This difference was not clinically significant. There was no significant difference in anteversion. There were no significant differences in the number of patients within the safe zones for inclination or anteversion, or in the number of patients experiencing a dislocation. No correlation was found between inclinometer measurement and measured acetabular component inclination. Inclinometer use and body mass index (BMI) were the sole statistically significant factors in determining acetabular component inclination.

This study indicated no current benefit to inclinometer use during primary THA, as measured by inclination, anteversion, and dislocation rate. However, this might be confounded by subtle variations in patient positioning, which may be a strong area of study in the future.

The online version contains supplementary material available at 10.1186/s42836-024-00258-y.