Is there an association between epiphyseal scar and osteonecrosis of the femoral head?

Purpose: To investigate statistical association between epiphyseal scar and osteonecrosis of the femoral head (ONFH) with magnetic resonance (MR) imaging. Patients and Methods: We retrospectively reviewed 71 consecutive patients who underwent MR imaging of bilateral hips that showed nontraumatic ONFH. There were 110 hips with ONFH and 31 normal hips; one hip received bipolar arthroplasty before the MR studies. All cases of ONFH had typical MR findings. The epiphyseal scars in the femoral head were classified as type I (a sealed-off scar) or type II (a perforated scar). Bone marrow edema, if present, in the proximal femur was identified on coronal T2-weighted or STIR MR images. Results: The type of femoral epiphyseal scar was clearly delineated in 97 hips. In cases with ONFH, a type I scar occurred in 46 hips (64%), and a type II scar in 26 hips (36%). In cases of ONFH with bone marrow edema, 69% of hips (24/35) had a type I scar and 31% of hips (11/35) had a type II scar. There was no statistical association between the type of epiphyseal scar and ONFH, regardless of staging (P=0.29), or the type of scar and bone marrow edema (P=0.42). Conclusion: There is not a significant statistical association between a sealed-off scar and ONFH. (Hip International 2009; 19: 382-5)