Clinical consequences of posttraumatic bone bruise in the knee

BACKGROUND: Bone bruise is often seen in posttraumatic knees, but the clinical relevance is unclear. HYPOTHESIS: The presence of bone bruise is associated with increased pain severity in patients with sustained knee trauma. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: We collected prospective data of 132 patients visiting their general practitioner after sustained knee trauma. Patients with bone bruise underwent a magnetic resonance imaging follow-up study that was discontinued when the bone bruise could no longer be discerned or after 1 year of follow-up. Bone bruise was assessed on magnetic resonance imaging, and pain severity was scored on a numeric rating scale (0-10) at baseline, and at 3, 6, and 12 months after trauma. The presence of bone bruise and pain severity (over time) were compared using linear regression analyses for repeated measurements. Adjustment was made for possible confounders: presence of meniscal tears, cruciate or collateral ligament ruptures, severe effusion, osteoarthritis, obesity, age, gender, work load, and sports load. RESULTS: At baseline as well as during follow-up, bone bruise was associated with a slightly higher pain score. The differences, however, were very small (adjusted difference in pain severity 0.34 or less) and not statistically significant nor clinically relevant. CONCLUSION: There is no statistically significant relationship, nor a clinically relevant relationship, between the presence of bone bruise and pain severity in patients with sustained knee injury in general practice.