Occult osseous injuries after ankle sprains: incidence, location, pattern, and age.

We retrospectively evaluated 109 magnetic resonance studies in patients with prior ankle sprains to investigate the frequency and pattern of bone bruises. Patterns of bone bruises were then correlated with the ligaments injured. In addition, the age of the injury was determined from medical records to correlate the presence of bone bruises with the temporal period from injury. Bone bruises occurred in 39% of ankle sprains. Multiple bone bruises were seen in 40% of those with bone bruises; they occurred more frequently in patients with multiple ligaments injured. The marrow changes may be secondary to impaction, rotary instability of the ankle, and microavulsion vectors. Bone bruise-like lesions were seen at an average of 8.4 weeks in age but were seen more than a year after the injury. We conclude that bone bruises frequently occur in patients with ankle sprains, and the marrow changes may be caused by one of the three proposed mechanisms.