Ryosuke Yamaguchi MD, Presenter: Nothing to Disclose

Takuaki Yamamoto MD, PhD, Abstract Co-Author: Nothing to Disclose

Goro Motomura, Abstract Co-Author: Nothing to Disclose

Satoshi Ikemura, Abstract Co-Author: Nothing to Disclose

Kenyu Iwasaki, Abstract Co-Author: Nothing to Disclose

Garida Zhao, Abstract Co-Author: Nothing to Disclose

Yukihide Iwamoto, Abstract Co-Author: Nothing to Disclose

To evaluate the characteristic morphology in patients with transient osteoporosis of the hip (TOH) radiographically.

Objectives were 33 hips of 31 TOH patients (25 men and 6 women, ages ranging from 28 to 64) and controls were 20 normal hips without any symptoms. Radiological parameters, including cross over (CO) sign, posterior wall (PW) deficiency, acetabular anteversion angles at roof edge (RE) and equatorial edge (EE) level, Sharp angle, Acetabular roof obliquity (ARO), center edge (CE) angle, acetabular head index (AHI) and anterior bump at head neck junction, were evaluated. In addition, the localization of the lowest signal intensity area was evaluated based on T1-weighted MR imaging by dividing the femoral head into 8 portions; superior, lateral, inferior and medial regions in the anterior and posterior parts.

TOH patients demonstrated significantly higher prevalences of CO sign (52%) and PW deficiency (27%) than the controls (0%; 0%) (p<0.0001, 0.0097). Especially, acetabular anteversion angles at RE and EE levels in TOH patients (-0.1; 13.9 deg) were significantly lower than those in the controls (14.2; 21.4 deg) (p<0.0001), suggesting that TOH patients had relatively retroverted acetabulum. Both Sharp angle and ARO were similar between both the groups, but CE angle and AHI in TOH patients (34.6 deg; 83.0%) were significantly lower than those in the controls (43.6 deg; 88.1%) (p<0.0001, 0.0073). TOH patients demonstrated anterior bump at the head neck junction (49%) than the controls (15%) (p=0.014). In 30 hips (91%) of TOH patients, the lowest signal intensity area existed in the superior region contacting to the articular surface close to the acetabular edge (anterior part, 48%; posterior part, 24%; both anterior and posterior, 18%).

This study indicated that TOH patients had relatively retroverted acetabulum, femoral head lateralization, and partial anterior head neck junction deformity. In addition, the lesion was mainly localized in the superior region of the femoral head close to the acetabular edge, suggesting an existence of a mechanical interaction between the head and acetabular edge.

Patients with transient osteoporosis of the hip have some morphological characteristics such as acetabular retroversion, which may be useful findings in considering the disease pathogenesis.

Yamaguchi, R, Yamamoto, T, Motomura, G, Ikemura, S, Iwasaki, K, Zhao, G, Iwamoto, Y, The Morphological Study of Transient Osteoporosis of the Hip.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12027200.html