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Clinical Orthopaedics and Related Research®
Published in: Clinical Orthopaedics and Related Research® 12/2012

01-12-2012 | Symposium: ABJS Carl T. Brighton Workshop on Hip Preservation Surgery

Can the Alpha Angle Assessment of Cam Impingement Predict Acetabular Cartilage Delamination?

Authors: Paul E. Beaulé, MD, FRCSC, Kelly Hynes, MD, Gillian Parker, BSc, Kyle A. Kemp, MSc

Published in: Clinical Orthopaedics and Related Research® | Issue 12/2012

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Abstract

Background

Substantial acetabular cartilage damage is commonly present in patients suffering from femoral acetabular impingement (FAI). A better understanding of which patient is at risk of developing substantial cartilage damage is critical for establishing appropriate treatment guidelines.

Questions/Purposes

We asked: (1) Does the cam deformity severity in FAI as assessed by alpha angle predict acetabular cartilage delamination? And (2) what are the clinical and radiographic findings in patients with acetabular cartilage delamination?

Methods

One hundred sixty-seven patients (129 males, 38 females) with a mean age of 38 years (range, 17–59 years) underwent joint preservation surgery for cam-type FAI. All data were collected prospectively. We assessed center-edge angle and Tönnis grade on AP radiographs and alpha angle on specialized lateral radiographs. Acetabular cartilage damage was assessed intraoperatively using the classification of Beck et al., with Type 3 and greater qualifying as delamination.

Results

For all hips, mean alpha angle was 65.5° (range, 41°–90°), and mean center-edge angle was 33.3° (range, 21°–52.5°). Patients with an alpha angle of 65° or greater had an odds ratio (OR) of 4.00 (95% CI, 1.26–12.71) of having Type 3 or greater damage. Increased age (OR, 1.04; 95% CI, 1.01–1.07) and male sex (OR, 2.24; 95% CI, 1.09–4.62) were associated with Type 3 or greater damage, while this was the opposite for acetabular coverage as assessed by center-edge angle (OR, 0.94; 95% CI, 0.89–0.99).

Conclusions

Patients with cam-type FAI and an alpha angle of 65° or more are at increased risk of substantial cartilage damage while increasing acetabular coverage appears to have a protective effect.

Level of Evidence

Level III, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.
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Metadata
Title
Can the Alpha Angle Assessment of Cam Impingement Predict Acetabular Cartilage Delamination?
Authors
Paul E. Beaulé, MD, FRCSC
Kelly Hynes, MD
Gillian Parker, BSc
Kyle A. Kemp, MSc
Publication date
01-12-2012
Publisher
Springer-Verlag
Published in
Clinical Orthopaedics and Related Research® / Issue 12/2012
Print ISSN: 0009-921X
Electronic ISSN: 1528-1132
DOI
https://doi.org/10.1007/s11999-012-2601-3

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