Untreated Asymptomatic Hips in Patients With Osteonecrosis of the Femoral Head

Abstract

Because there is no consensus regarding the factors predicting femoral head collapse in asymptomatic osteonecrosis of the hip, we studied the risk factors for collapse. Between 1990 and 2000, we used MRI to confirm asymptomatic osteonecrosis of the femoral head in 81 patients (81 hips) whose other hip had nontraumatic symptomatic osteonecrosis and we monitored them prospectively. The minimum followup was 5 years (mean, 8.3 years; range, 5-16 years). At the latest followup, 31 hips (38%) were symptomatic and 26 hips (32%) had collapsed. The mean interval between diagnosis and collapse was 4.1 years. We observed no correlation between femoral head collapse and patients' age, gender, weight, presumed cause of osteonecrosis, or length of followup. With combined factors, only extent of large necrotic lesion (hazard ratio, 4.06; 95% confidence interval, 1.29-12.77) and location of Type C2 necrotic lesion (hazard ratio, 6.35; 95% confidence interval, 1.18-34.11) predicted collapse.

Treatment of Femoral Head Osteonecrosis in the United States: 16-year Analysis of the Nationwide Inpatient Sample

“…Despite a poorly understood pathophysiology, it is known that patients in their third decade of life are at highest risk and that there is an annual prevalence of 10,000 to 20,000 new cases per year in the United States [47]. Left untreated, the natural history of the disease will progress to end-stage degenerative joint disease in greater than 80% of symptomatic cases and nearly two-thirds of asymptomatic ones [46,47,51].…”

Bilateral Idiopathic Osteonecrosis of the Femoral Head: A Case Report With an Emphasis on Differential Diagnosis, Imaging, and Treatment

“…In one recent study, 32% of asymptomatic hips with ONFH collapsed within 4 years. 13 In this study by Min et al, collapse was preceded by symptoms for 8 months on average. Lesion size and lesion location appear to be most predictive for progression to symptoms and collapse, with large, lateral lesions being the most worrisome.…”

“…3 As revealed in this case, idiopathic ONFH can be bilateral in up to 60% of cases at initial diagnosis. 13 However, if an MRI of the contralateral hip is normal at initial diagnosis, the risk of subsequent development of ONFH is rare. 14 Even if ONFH is present bilaterally, the patient will invariably present with unilateral symptoms.…”

“…14 Even if ONFH is present bilaterally, the patient will invariably present with unilateral symptoms. 13 These symptoms range from mild anterior hip stiffness to marked pain with gait disturbances and limitations in range of motion. 1 This case is unique due to the involvement of the contralateral hip and the rapid clinical progression of the disease.…”

“…Lesion size and lesion location appear to be most predictive for progression to symptoms and collapse, with large, lateral lesions being the most worrisome. 13,27 Currently, there is no accepted treatment protocol for asymptomatic ONFH; therefore, an aim for future research could be to examine the effectiveness of non-operative and operative interventions on these asymptomatic hips.…”