Yasuhiro Asakura

Showa University, Shinagawa, Tōkyō, Japan

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Publications (4)6.22 Total impact

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    ABSTRACT: Transtrochanteric anterior rotational osteotomy results in improvement of joint congruity and prevention of progressive collapse and osteoarthritic changes in patients with femoral head osteonecrosis. However, this procedure remains controversial for patients with extensive collapse due to potential osteoarthritis caused by postoperative instability. The purpose of this study was to evaluate hip instability after osteotomy and determine the relation between instability and radiological and clinical outcomes. In all, 27 hips of 24 patients that were followed up for a mean period of 3.8 years were included. Instability was defined as more than 1 mm translation of the femoral head in transverse computed tomography scans obtained at 0 degrees and 45 degrees flexion of the hip joint. Hips were divided into instability and stability groups. Eleven hips (40%) developed instability after surgery. Osteophytes on the femoral head in 10 hips of the instability group and 2 hips of the stability group had increased in size at follow-up. There was a significant relation between postoperative instability and osteophyte formation. Joint space narrowing was not seen in any of the cases. There was no significant difference between the groups in either the postoperative intact ratio of the femoral head or the Japanese Orthopaedic Association hip score. Neither instability nor osteophyte formation on the femoral head after transtrochanteric anterior rotational osteotomy correlated with progressive osteoarthritic changes or clinical outcome in the presence of an adequate femoral head intact ratio facing the weight-bearing area.
    Journal of Orthopaedic Science 09/2009; 14(5):535-42. DOI:10.1007/s00776-009-1363-6 · 0.94 Impact Factor
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    ABSTRACT: Non-traumatic osteonecrosis involving the femoral head frequently occurs in young patients especially due to steroids administration or other some reasons. In cases of extensive lesion of the weight-bearing area, collapse is usually progressive. Preservation of the joint in young patients to avoid joint replacement procedures is important and widely accepted. Transtrochanteric rotational osteotomy for the femoral head osteonecrosis is ideal procedure moving the remained viable femoral head area to the loaded portion below the acetabular roof, thus hip joints can be preserved for long term by remodeling even if the stage is progressed preoperatively. This procedure is technically difficult, but should be common in orthopaedic surgeons.
    Clinical calcium 07/2007; 17(6):923-30.
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    ABSTRACT: Posterior rotational osteotomy in 48 hips of 40 young patients with femoral head osteonecrosis with extensive and apparent collapsed lesions were reviewed with a mean of 9.2 years of follow-up. No viable area was seen on the articular surface of the femoral head of the loaded portion on preoperative anteroposterior radiographs in all femoral heads. All hips had greater than 3 mm collapse; 40 hips showed no apparent joint narrowing, and 8 hips revealed joint narrowing. Posterior viable area of joint surface before surgery ranged from 6% to 29%, with a mean of 19%, on lateral radiographs. Anterior viable area ranged from 6% to 42% with a mean of 21%. The mean age of the patients was 29 years, with 13 women and 27 men. Thirty-five hips were nontraumatic, and 13 were traumatic. Mean postoperative viable area below the acetabular roof was 59% on anteroposterior radiographs and 54% on 45° flexed radiographs. Recollapse was prevented in 44 hips (92%), with adequate viable area on the loaded portion on final follow-up radiographs. Progressive joint narrowing was found in 9 hips. Resphericity of the postoperative transferred medial collapsed area of the femoral head was observed on 34 of 35 hips on final anteroposterior radiographs. The joint space was increased in 6 of 8 hips. Posterior rotational osteotomy appeared to be effective in delaying the progression of degeneration in young patients with extensive collapsed osteonecrotic lesions.
    12/2006: pages 89-96;
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    ABSTRACT: In young patients with nontraumatic femoral head osteonecrosis with extensive and collapsed lesions, joint preservation is a goal if total joint arthroplasty is to be avoided. We evaluated the effectiveness of a posterior rotational osteotomy in this patient population. We reviewed thirty-five hips in twenty-eight young patients with nontraumatic femoral head osteonecrosis treated by posterior femoral neck rotational osteotomy. All femoral heads were collapsed, and seven hips showed joint-space narrowing. Lateral radiographs of the femoral head revealed that 15% of the mean posterior portion and 17% of the mean anterior portion of the femoral head consisted of radiographically apparent living bone. The mean age of the patients (ten women and eighteen men) was twenty-eight years. The mean follow-up period was eight years. Less than six months after surgery, the radiographically apparent area of living bone of the femoral head below the acetabular roof was shown to be 59% on the standard anteroposterior radiograph and 54% on the 45 degrees -flexion radiograph. In thirty-three hips (94%), further collapse of the femoral head was prevented and an adequate amount of living bone was demonstrated on the loaded lateral portion of the femoral head on the final follow-up radiographs. Progressive joint-space narrowing was seen in four hips. In young patients with osteonecrosis and extensively collapsed lesions of the femoral head, posterior femoral neck rotational osteotomy appears to be effective in delaying the progression of degeneration if an adequate area of living bone can be placed under the loaded lateral portion of the acetabulum. Therapeutic Level IV. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.
    The Journal of Bone and Joint Surgery 12/2006; 88 Suppl 3:42-7. DOI:10.2106/JBJS.F.00767 · 5.28 Impact Factor