Acetabular reconstruction with Chiari pelvic osteotomy: report of 2 cases.

We performed cementless total hip arthroplasty combined with acetabular reconstruction with Chiari pelvic osteotomy on 3 hips in 2 patients. This procedure increased the osseous coverage of the shell and decreased the load around the hip by medialization of the hip center. Osteosynthesis of the proximal and distal bone fragment was performed using a shell with screws. Nonunion between the proximal and distal fragments was not noticed to include the case with small contact area. Postoperative dislocation had not occurred in these cases as of 1 year after surgery. This method may be an effective solution for severe dysplasia and revision surgery.

Contrast-enhanced MR imaging of subchondral insufficiency fracture of the femoral head: a preliminary comparison with that of osteonecrosis of the femoral head.

INTRODUCTION: Subchondral insufficiency fracture of the femoral head (SIF) may be confused with osteonecrosis of the femoral head (ON) due to clinical and imaging similarities. MATERIALS AND METHODS: Contrast-enhanced MR images in patients with SIF (ten hips in ten patients) were retrospectively reviewed and compared with those from patients with ON (ten hips in six patients). RESULTS: Low-signal intensity bands on T1-weighted images were present within the femoral head in all hips examined. The segment proximal to the band was contrast-enhanced following IV gadolinium administration in nine of ten hips (90%) with SIF and in none of the 10 hips with ON. CONCLUSION: These results suggest that the presence of contrast enhancement in the segment proximal to the low-signal intensity band in the femoral head may serve as a supplemental diagnostic measure for the differentiation of SIF from ON.

Short-term wear of Japanese highly cross-linked polyethylene in cementless THA.

INTRODUCTION: Production of polyethylene wear from acetabular liners is thought, in part, to mediate the periprosthetic osteolysis. This study examined the in vivo wear performance of Japanese highly cross-linked polyethylene (Aeonian) in cementless total hip arthroplasty. MATERIALS AND METHODS: Ninety-five hips received a highly cross-linked polyethylene liner, while 20 hips were implanted with conventional polyethylene. Two-dimensional linear wear was measured on radiographs and volumetric wear was then calculated. Both linear and volumetric wear rates were examined for the 1-year postoperative period as well as for the time frame beginning after 1 year ending with the final follow-up. RESULTS: The amount of linear wear was significantly lower in the cross-linked group at 3 and 5 years postoperatively (P < 0.01 and < 0.001, respectively). Linear and volumetric wear rates after 1 year postoperatively for hips with the cross-linked polyethylene were significantly reduced by 57 and 59%, respectively, when compared to rates for those who received conventional polyethylene (P < 0.01). A multiple logistic regression analysis revealed that cross-linking was a significant factor influencing linear wear rate after 1 year postoperatively with an odds ratio, exp(ss) = 10.033 (P < 0.001). CONCLUSION: These results suggest that the highly cross-linked polyethylene reduces penetration of the femoral head and may be an optimal bearing surface for patients receiving total hip arthroplasty.

A subchondral fracture in transient osteoporosis of the hip.

Although subchondral changes are reported to be associated with transient osteoporosis of the hip (TOH), the etiology of this disorder is unknown.In this paper, we describe a 45-year-old man with TOH who underwent both MRI and CT examinations. Plain radiographs obtained 2 months after the onset of hip pain showed a focal loss of radiodensity in the left femoral head. MRI revealed a bone marrow edema pattern in the left femoral head and neck with an associated subchondral serpiginous low signal intensity line on the T1-weighted images. A CT scan showed a subchondral fracture in the corresponding area. The hip pain and imaging abnormalities resolved spontaneously following conservative treatment. This case study demonstrated that a subchondral fracture of the femoral head was associated with TOH using MRI and CT examinations, and suggests that the presence of a subchondral fracture may be important for the pathophysiology of TOH.