Cam morphology is strongly and consistently associated with development of radiographic hip osteoarthritis throughout 4 follow-up visits within 10 years

Objective: 

To determine the association between cam morphology and the development of radiographic hip osteoarthritis (RHOA) at four time points within 10-year follow-up. 

Design: 

The nationwide prospective Cohort Hip and Cohort Knee study includes 1002 participants aged 45–65 years with 2-, 5-, 8-, and 10-year follow-ups. The associations of cam morphology (alpha angle >60°) and large cam morphology (alpha angle >78°) in hips free of osteoarthritis at baseline (Kellgren & Lawrence (KL) grade <2) with the development of both incident RHOA (KL grade≥2) and end-stage RHOA (KL grade≥3) were estimated using logistic regression with generalized estimating equation at each follow-up and using Cox regression over 10 years, adjusted for age, sex, and body mass index.

Results: 

Both cam morphology and large cam morphology were associated with the development of incident RHOA at all follow-ups with adjusted Odd Ratios (aORs) ranging from 2.7 (95% Confidence interval 1.8–4.1) to 2.9 (95% CI 2.0–4.4) for cam morphology and ranging from 2.5 (95% CI 1.5–4.3) to 4.2 (95% CI 2.2–8.3) for large cam morphology. For end-stage RHOA, cam morphology resulted in aORs ranging from 4.9 (95% CI 1.8–13.2) to 8.5 (95% CI 1.1–64.4), and aORs for large cam morphology ranged from 6.7 (95% CI 3.1–14.7) to 12.7 (95% CI 1.9–84.4). 

Conclusions: 

Cam morphology poses the hip at 2–13 times increased odds for developing RHOA within a 10-year follow-up. The association was particularly strong for large cam morphology and end-stage RHOA, while the strength of association was consistent over time.