Acetabular labral tear complicating idiopathic osteonecrosis of the femoral head treated by labral repair with hip arthroscopy: a case report.

INTRODUCTION: It has been well documented that labral tear is frequently associated with femoroacetabular impingement and dysplasia of the hip; however, there have been few reported cases of labral tear associated with idiopathic osteonecrosis of the hip. Here we report the case of a patient with labral tear associated with idiopathic osteonecrosis of the femoral head who was treated by hip arthroscopy, with a favorable short-term outcome.

CASE PRESENTATION: Under the diagnosis of systemic lupus erythematosus, a 28-year-old Japanese woman was treated with the oral administration of steroid in 2007. A year after the treatment, she developed right hip joint pain and was diagnosed with idiopathic osteonecrosis of the femoral head at our institution. In November of 2011, she revisited our hospital when her right hip joint pain exacerbated and she became unable to walk. On the visit, the anterior impingement sign and Patrick test were positive. Radiography and magnetic resonance imaging in 2011 demonstrated neither spreading of the osteonecrosis area nor collapse of the femoral head in the right joint; however, magnetic resonance imaging showed a high-intensity area in the articular labrum in a T2-weighted image, leading to a diagnosis of labral tear. She underwent labral repair with hip arthroscopy in August of 2012. Now, 1 year after surgery, she does not feel any pain during walking and her modified Harris hip score has improved from 20 prior to surgery to 85.

CONCLUSION: The case indicated that it is important to be aware of the possibility of labral tear in patients with idiopathic osteonecrosis of the femoral head, when spreading of the osteonecrosis area or collapse of the femoral head has not been seen on magnetic resonance imaging.