Differences in highly cross-linked polyethylene wear between zirconia and cobalt-chromium femoral heads in Japanese patients: a prospective, randomized study.

The purpose of this study was to compare highly cross-linked polyethylene wear between the zirconia head and the cobalt-chromium head in Japanese patients. A prospective, randomized study was performed to evaluate the outcomes in 32 hips that had zirconia heads and in 30 hips that had cobalt-chromium heads. The mean follow-up periods of both groups were same (5 years). There were no significant differences between the zirconia head and the cobalt-chromium head in the mean polyethylene linear wear per year and the mean volumetric polyethylene wear per year in the steady phase. This study indicates that zirconia head offers no benefits over metal head in terms of wear reduction at 5 years in Japanese patients who have lightweight and thin polyethylene liners.

Computed tomography-based custom-made stem for dysplastic hips in Japanese patients.

We investigated 55 hips of 53 patients with dysplastic hips. Individual computed tomography data were used in the manufacturing of cementless custom-made stems made of Ti-6Al-4V. The proximal one third was coated using porous coating covered with hydroxyapatite coating. The average age at surgery was 60 years and the average follow-up was 7 years. Five patients (9%) complained of postoperative thigh pain. According to Engh's radiologic classification system, there was bone-ingrown fixation in all hips. The cortical index and canal flare index were lower, and stem diameter was greater in the 11 hips (20%) with severe stress shielding than in the remaining 44 hips. Although the results obtained with this custom-made stem system for dysplastic hips were excellent, stress shielding is still an issue.

Indications for free vascularized fibular grafting for the treatment of osteonecrosis of the femoral head.

BACKGROUND: The present study aimed to determine the indications for free vascularized fibular grafting for the treatment of osteonecrosis of the femoral head. METHODS: Seventy-one hips (60 patients) were clinically followed for a minimum of 3 years. Average follow-up period was 7 years. Etiologies were alcohol abuse in 31 hips, steroid use in 27, idiopathic in 7 and trauma in 6. Preoperative staging of the necrotic lesion was done using the Steinberg's classification system. The outcomes of free vascularized fibular grafting were determined clinically using the Harris hip-scoring system, radiographically by determining progression, and survivorship by lack of conversion to total hip replacement. RESULTS: The average preoperative Harris hip score was 56 points and the average score at the latest follow-up examination was 78 points. Forty-seven hips (67%) were clinically rated good to excellent, 4 hips (6%) were rated fair, and 20 hips (28%) were rated poor. Thirty-six hips (51%) did not show radiographic progression while 35 hips (49%) did, and with an overall survivorship of 83% at 7 years. Steroid-induced osteonecrosis was significantly associated with poor scores and survival rate (68%). Preoperative collapse was significantly associated with poor scores, radiographic progression and poor survival rate (72%). A large extent of osteonecrosis greater than 300 degrees was significantly associated with poor scores, radiographic progression and poor survival rate (67%). There was no relationship between the distance from the tip of the grafted fibula to the subchondral bone of the femoral head and postoperative radiographic progression. CONCLUSION: In conclusion, small osteonecrosis (less than 300 degrees of the femoral head) without preoperative collapse (Steinberg's stages I and II) is the major indication for free vascularized fibular grafting. Steroid-induced osteonecrosis is a relative contraindication. Large osteonecrosis (greater than 300 degrees) with severe preoperative collapse (greater than 3 mm) is a major contraindication. Hips with 2 negative factors such as severe preoperative collapse and a large extent of osteonecrosis, require hip replacements.

Tissue-engineered approach for the treatment of steroid-induced osteonecrosis of the femoral head: transplantation of autologous mesenchymal stem cells cultured with beta-tricalcium phosphate ceramics and free vascularized fibula.

Autologous mesenchymal stem cells (MSCs) cultured with beta-tricalcium phosphate (beta-TCP) ceramics and with a free vascularized fibula were transplanted into three patients with steroid-induced osteonecrosis of the femoral head. The average follow-up period was 34 months and the average patient age at the time of surgery was 28 years old. Fifteen milliliters of bone marrow was obtained from the patients 4 weeks before surgery, and was used for in vitro proliferation of MSCs. beta-TCP granules were immersed in the MSC suspension and the cells were further cultured for 2 weeks. Cultured MSCs/beta-TCP composite granules were implanted into the cavity that remained after curettage of necrotic bone; and finally, a free vascularized fibula was grafted. All hips showed preoperative collapse and radiographic progression was observed in two hips postoperatively. Osteonecrosis did not progress any further and early bone regeneration was observed. This tissue-engineered approach has potentials for the treatment of osteonecrosis. However, our results suggested that the present procedure could not be used for cases with severe preoperative collapse.

Twenty-five years followup of patients who had valgus osteotomy for arthritic hips.

We reviewed the long-term outcomes of intertrochanteric valgus femoral osteotomies in patients with arthritic hips to clarify any influencing factors. One hundred six patients (127 hips) were followed up during an average of 25 years. The average age of the patients at surgery was 42 years. The preoperative extent of degenerative change was classified radiologically into one of four grades according to the criteria of Tönnis. Radiographic measurements of acetabular coverage were made using AP radiographs obtained immediately after surgery. Thirty-eight patients (41 hips) had total hip arthroplasties; the 25-year survival rate was 69%. Radiologic evaluations of patients with mild preoperative degenerative changes (Tönnis Grade 1) improved and good clinical outcomes were obtained. In addition, radiologic evaluations of patients whose hips had better acetabular coverage (center-edge angle > 0 degrees, sharp angle < 50 degrees, or acetabular head index > 60%) also improved. However, radiographic measurements did not influence clinical scores. The mean score of patients younger than 50 years at surgery was higher than patients older than 50 years. The mean score of patients with unilateral hip involvement was higher than patients with bilateral involvement. Therefore, valgus osteotomies seem appropriate for younger patients with unilateral involvement.

Four-angle radiographic assessment of cement mantle thickness in cemented total hip arthroplasty.

In this study, the cement mantle thickness of 57 hips undergoing primary cemented total hip arthroplasty (THA) were investigated with 4 angle radiographs. All surgeries were performed with a standardized posterolateral surgical approach. In addition to conventional anteroposterior and lateral radiographs, obturator oblique and iliac oblique radiographs were taken. In the evaluation of the cementing grade on the anteroposterior radiograph, the incidence of hips with thin cement mantles was 25%. In evaluating the cementing grade on the anteroposterior and lateral radiographs, we found an incidence of hips with thin cement mantles of 37%. From the evaluations with 4 angle radiographs, 10 hips were additionally assigned as being of a poor cementing grade (Mulroy's grade C-2). Thin cement mantles were mainly seen on the iliac oblique radiographs.