Osteotomy linked to longer hip survival in true dysplasia, not in borderline hips

Design

Retrospective cohort with Kaplan-Meier and Cox analysis

Population

683 osteotomy-treated hips and 353 untreated contralateral hips

Primary outcome

Tönnis grade 3 arthritis or conversion to hip replacement

Effect

Dysplasia 20-year survival 88% (80–93) with osteotomy vs 69% (55–80) untreated

This Bone & Joint Journal study, published on 1 September, reviewed 683 hips treated with transposition osteotomy of the acetabulum and 353 untreated opposite hips, classified by lateral centre-edge angle: dysplasia under 20°, borderline 20° to under 25°, normal 25° or more. Median follow-up was about ten years; failure meant progression to Tönnis grade 3 arthritis or hip replacement.

Untreated dysplastic hips had 69% 20-year survival, against 96% for borderline and 100% for normal hips. In dysplasia, osteotomy-treated hips survived better (88% vs 69%). In borderline hips, osteotomy did not significantly improve failure-free survival (100% vs 96%), although arthritis progressed less. Higher BMI and a smaller centre-edge angle predicted failure.

This supports reorientation osteotomy in true dysplasia as possibly disease-modifying, and argues for caution in borderline hips, whose natural history in this series was good. It is retrospective and compares treated hips with the patient's other hip, which is not a randomised control.

• Measure the lateral centre-edge angle and record which category the hip falls in.
• In true dysplasia (under 20°), discuss acetabular reorientation early in suitable patients.
• In borderline hips (20° to under 25°), weigh the good untreated course before offering osteotomy.
• Address BMI; it predicted failure in both treated and untreated hips.
• Consider age: older age predicted failure after osteotomy in dysplasia.

Why it matters

The centre-edge angle does not just classify dysplasia; it may decide who benefits from an osteotomy at all.

Don't overread it

This was retrospective and non-randomised; the treated and untreated hips were chosen for different reasons.

The statistics, in plain English

Twenty-year survival of 88% versus 69% means about 19 more hips per 100 avoided advanced arthritis or replacement over two decades. In borderline hips, the interval for arthritis-free survival (79%, 95% CI 22 to 96) is very wide because few hips reached 20 years.

Read the rest in the app

You have read your two free briefings this month. The app carries all 27 specialties, every morning, free — and this finding is waiting in it.

Get Daily Doctor — free

Scan to keep reading on your phone. No account needed to start.