What causes cup inclination outliers in primary total hip arthroplasty when using a digital inclinometer? A…

Cohort studyHip international : the journal of clinical and experimental research on hip pathology and therapy· Aug 2026

What causes cup inclination outliers in primary total hip arthroplasty when using a digital inclinometer? A prospective cohort study.

Geert Meermans, Willem J Van Doorn, Jan-Jaap Kats … George Grammatopoulos

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ArthroplastyCohort studyClinical practiceQ2IF 1.9

Digital inclinometer-guided cup placements reached target inclination angle in 74% of cases.

What causes cup inclination outliers in primary total hip arthroplasty when using a digital inclinometer? A prospective cohort study.

Geert Meermans … George Grammatopoulos

Hip international · Aug 2026 · Q2 in Orthopedics

Background

A suboptimal radiographic inclination (radiographic inclination) angle of the cup has been associated with worse short- and long-term outcomes after primary total hip arthroplasty (total hip arthroplasty).

Methods

In this prospective study, we included 200 consecutive patients undergoing primary total hip arthroplasty.

n = 186 patients

74%

Results

74%

most cups landed in the target angle range, over 1 in 4 did not

n = 186 patients

More results

The mean radiographic inclination was 37.9° SD 4.7.

There were 53 outliers (26.5%) for the 35-45° zone.

The mean absolute Δintraoperative inclination cup -intraoperative inclination target was 1.2° SD 1.0.

More results

The absolute Δintraoperative inclination cup -intraoperative inclination target was <1° in 108 patients (54%), <2° in 160 patients (80%) and <3° in 186 patients (93%).

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Conclusion · 1 of 2

Using a digital inclinometer allowed the surgeons to intraoperatively put the cup within 3° of the intraoperative inclination target in 93% of cases.

Conclusion · 2 of 2

This led to 74% of the acetabular components being placed within an radiographic inclination target zone of 35°- 45°. The remaining outliers were caused by more of less than average deviation of the pelvic position at time of impaction.

What causes cup inclination outliers in primary total hip arthroplasty when using a digital inclinometer? A prospective cohort study.

What causes cup inclination outliers in primary total hip arthroplasty when using a digital inclinometer? A prospective cohort study.

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