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Hip resurfacing revision rates: radiological audit of risk factors
N Ramisetty1, K M Krishnan, P F Partington
1Department of Orthopaedics and Trauma Surgery, Wansbeck General Hospital, UK. narenrami@yahoo.co.uk
Insights
Hip resurfacing revision rates are higher with abnormal cup inclination angle (CIA) and stem shaft angle (SSA). A CIA of ≥60° correlates with a 10% revision rate, identifying a high-risk group for monitoring.
Area of Science:
- Orthopedic surgery
- Radiology
- Implant survival analysis
Background:
- Hip resurfacing is an alternative to total hip replacement.
- Abnormal cup inclination angle (CIA) and stem shaft angle (SSA) are known risk factors for hip resurfacing revision.
- Radiological auditing is crucial for assessing implant outcomes.
Purpose of the Study:
- To audit hip resurfacing radiological outcomes within a specific trust.
- To identify the typical CIA and SSA in hip resurfacing procedures.
- To determine the revision rate associated with specific CIA and SSA values, particularly a CIA of ≥60° and a varus SSA (>0°).
Main Methods:
- Retrospective radiological audit of 247 hip resurfacing procedures performed between April 2003 and March 2008.
- Radiographs were analyzed to record CIA and SSA for 221 eligible patients.
- Revision rates were calculated based on CIA and SSA measurements.
Main Results:
- The mean CIA was 47.6°, with 13% of patients exhibiting a CIA >60°.
- The mean SSA was 1.4° varus, with 67% of patients having a varus SSA.
- A statistically significant higher revision rate (10%) was observed in patients with a CIA of ≥60° compared to those with a CIA <60° (1%) (p=0.017).
Conclusions:
- Abnormal CIA and SSA measurements can identify hip resurfacing patients at higher risk of revision.
- A CIA of ≥60° is associated with a substantial 10% revision rate, warranting close long-term follow-up.
- Hospitals and surgeons should critically review their radiological outcomes to identify and manage patients at risk of revision surgery.
Introduction:
We performed a retrospective radiological audit of the hip resurfacings carried out in our trust over a five-year period. Abnormal cup inclination angle (CIA) and stem shaft angle (SSA) are recognised risk factors for revision in hip resurfacing. Our aims were to identify the CIA and SSA for hip resurfacings in our trust, to determine the revision rate in a CIA of ≥60° and an SSA of >0° varus, thereby identifying a high risk group for close, long-term follow up.
Methods:
A total of 247 patients underwent hip resurfacing in our trust between April 2003 and March 2008. The CIA and SSA were recorded. Of the 247 patients, 26 were excluded as there were no appropriate radiographs and so results were analysed for 221 patients.
Results:
The mean CIA was 47.6°. Over a third of the patients (34%) had a CIA of >50° and 13% had >60°. The mean SSA was 1.4° varus. Over two-thirds of the patients (67%) had a varus SSA. There were six revisions but one was excluded as it was secondary to infection. The revision rate was 10% in patients with a CIA of ≥60° and 1% in those with a CIA of <60° (p=0.017), and 1% in a varus and 4% in a valgus SSA ((p)>0.05) respectively.
Conclusions:
The measurement of the CIA and SSA in hip resurfacings has identified a high risk group for close long-term follow up. There is already a 10% revision rate in those patients with a CIA of >60°. Hip resurfacing may generate a large revision burden in the 'average' surgeon's hands and all hospitals/surgeons should review their radiological outcomes critically and identify those at risk of revision.
