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Prevalence of associated deformities and hip pain in patients
with cam-type femoroacetabular impingement 2009

D. Allen, MSc, FRCS,
Ed(Trauma & Orth), Consultant Orthopaedic Surgeon1; P. E. Beaulé, MD, FRCS C,
Associate Professor2; O. Ramadan, MD, Resident Adult Reconstruction Service2;
and S. Doucette, MSc, Statistician2
1 Hairmyres Hospital, Eaglesham Road, East Kilbride G75 8RG, UK.
2 Ottawa Hospital Research Institute The Ottawa Hospital, General Campus, 501
Smyth Road, Ottawa, Ontario, Canada K1H 8L6.

Correspondence should be sent to Associate Professor P. E. Beaulé; e-mail:
pbeaule@ottawahospital.on.ca

Femoroacetabular impingement is a cause of hip pain in adults and is potentially
a precursor of osteoarthritis. Our aim in this study was to determine the
prevalence of bilateral deformity in patients with symptomatic cam-type
femoroacetabular impingement as well as the presence of associated acetabular
abnormalities and hip pain. We included all patients aged 55 years or less seen
by the senior author for hip pain, with at least one anteroposterior and lateral
pelvic radiograph available. All patients with dysplasia and/or arthritis were
excluded. A total of 113 patients with a symptomatic cam-impingement deformity
of at least one hip was evaluated. There were 82 men and 31 women with a mean
age of 37.9 years (16 to 55).

Bilateral cam-type deformity was present in 88 patients (77.8%) while only 23 of
those (26.1%) had bilateral hip pain. Painful hips had a statistically
significant higher mean alpha angle than asymptomatic hips (69.9° vs 63.1°, p <
0.001). Hips with an alpha angle of more than 60° had an odds ratio of being
painful of 2.59 (95% confidence interval 1.32 to 5.08, p = 0.006) compared with
those with an alpha angle of less than 60°. Of the 201 hips with a
cam-impingement deformity 42% (84) also had a pincer deformity.

Most patients with cam-type femoroacetabular impingement had bilateral
deformities and there was an associated acetabular deformity in 84 of 201
patients (42%). This information is important in order to define the natural
history of these deformities, and to determine treatment.