Send to

Choose Destination
  • The following term was not found in PubMed: Dec;470.
Clin Orthop Relat Res. 2012 Dec;470(12):3361-7. doi: 10.1007/s11999-012-2601-3.

Can the alpha angle assessment of cam impingement predict acetabular cartilage delamination?

Author information

Division of Orthopaedic Surgery, The Ottawa Hospital-General Campus, 501 Smyth Road, Box 502, Ottawa, Ontario K1H 8L6, Canada.



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.


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?


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.


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).


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 III, prognostic study. See the Instructions for Authors for a complete description of levels of evidence.

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Wolters Kluwer Icon for PubMed Central
Loading ...
Support Center