Apparent avascular necrosis of the hip: appearance and spontaneous resolution of MR findings in renal allograft recipients.

Abstract

The sensitivity of magnetic resonance (MR) imaging in the detection of avascular necrosis (AVN) of the hip and natural history of the MR findings were determined prospectively in renal allograft recipients, a group at risk for development of the disease. One hundred four patients were studied up to 24 months after transplantation. In 25 hips in 14 patients, MR findings were consistent with AVN. Pain developed in seven hips in four patients; in each hip, the MR images showed abnormality before the onset of symptoms. Plain radiographs showed abnormality in all hips that became painful; however, the plain radiographs of 17 of 18 asymptomatic hips in which MR imaging showed evidence of AVN showed no abnormality over a mean follow-up period of 16 months. All MR lesions in the symptomatic hips were larger than those in the asymptomatic cohort. MR lesions in seven hips (in five asymptomatic patients) regressed in size; in six hips, the MR images returned to normal. The findings suggest that some patients with MR evidence of AVN of the hip have spontaneous improvement.

Transient Bone Marrow Edema in Renal Transplantation: A Distinct Post‐transplantation Syndrome with a Characteristic MRI Appearance

“…As in previous studies these changes regressed within 3 months and the MR scans became normal (5). This is not the case with AVN, as an abnormal signal in AVN takes many months to resolve (10).…”

Untreated Asymptomatic Hips in Patients With Osteonecrosis of the Femoral Head

“…Recently, Hernigou et al [9] reported pain developed in 91% and collapse had occurred in 77% in asymptomatic ON associated with sickle cell disease. However, several investigators [5,17,21] have shown using MRI certain small lesions spontaneously heal and decrease in size over time.…”

“…Most researchers have reported ON of the femoral head generally has a progressive course of collapse once changes are apparent radiographically [1,12,24]. However, asymptomatic hips in the early stage of ON have variable paths of disease progression [13,14,17,22,24,29]. Ito et al [13] observed there was no difference in occurrence of progression between hips with Steinberg Stage I disease and hips with Stage II disease.…”

“…However, with the advent of MRI, it became easier to diagnose asymptomatic disease and to more accurately ascertain the extent, location, and stage of the necrotic lesion [2,17,28].…”

Fate of Untreated Asymptomatic Osteonecrosis of the Femoral Head

“…Discussion P revious studies of asymptomatic osteonecrosis of the femoral head have demonstrated various rates of disease progression 5,[20][21][22][23][24][25][26][27][28] . Differing opinions regarding the fate of asymptomatic disease have been attributed to several reasons, including differences in study populations, diagnostic modalities, follow-up periods, and the definition of disease progression 5,27 .…”