Bone Area Provides a Responsive Outcome Measure for Bone Changes in Short-term Knee Osteoarthritis Studies.

Objective: To analyze the 3-D bone area from an osteoarthritis (OA) cohort demonstrating no change in cartilage thickness.
Methods: Twenty-seven women with painful medial knee OA had magnetic resonance images at 0, 3, and 6 months. Images were analyzed using active appearance models.
Results: At 3 and 6 months, the mean change in medial femoral bone area was 0.34% (95% CI 0.04-0.64) and 0.61% (95% CI 0.32-0.90), respectively. Forty-one percent of the subjects had progression greater than the smallest detectable difference at 6 months.
Conclusion: In this small cohort at high risk of OA progression, bone area changed at 3 and 6 months when cartilage morphometric measures did not.