The changes of stress distribution in the femoral head with Perthes disease were observed under several condition. Finite element models were constructed referring to X-ray images and magnetic resonance images of the intact hip joint. The model was divided into five parts: cancellous bone, articular cartilage, necrotic bone, cortical bone, physeal cartilage. Material properties were alloted to these components by the past literature. The body weight and abductor muscle force were applied as loading. The model was altered to study the effect of age, the extent of necrosis, and lateralization of the fomoral head. Analysis were performed on a digital computer PC-9821(NEC) using the finite element program. There was no significant difference in stress distribution patterns regardless of age or extent of necrosis. However, compressive stresses were concentrated on the lateral portion of the epiphysis by lateralization of femoral head. The femoral head deformity in Perthes disease was more affected by the lateralization than by the age and the extent of necrosis.

We assessed the usefulness of vascularized bone transfer for treatment of aggressive musculoskeletal tumours. Classification by reconstruction method with vascularized bone transfer of our 33 patients was made into five types: 1) intercalary type in 6 cases, 2) arthrodesis type in 5 cases, 3) arthroplasty type using fibular head in 8 cases, 4) hybrid type with recycling autograft as heat treated bone or irradiated bone in 4 cases, and 5) inlay type after curettage of benign tumour chiefly for femoral head and/or neck in 10 cases.

From October 1975 to December 1999, 33 patients composed of 18 males and 15 females with age ranging from 9 to 69 years (average of 30 years) received vascularized bone transfer. There were 28 cases of bone tumour and 5 cases of soft tissue tumour. In 31 cases we grafted the fibula of 8 to 20 cm in size and in 2 cases the ileum of 8 cm in size. Postoperative follow-up period ranged from 10 months to 15 years with average of 65 months.

Primary union was achieved in 31 cases postoperatively between 1.5 month and 4 months with average of 3 months. As complication, we observed fracture of the graft in 4 cases and local recurrence in 3 cases. Postoperative functional evaluation ranged from 33.3% to 96.7% with average of 76.7%. As for oncological therapeutic results, continuous disease free cases accounted for 27, case of no evidence of disease for 1, case alive with disease for 1, and cases of death of disease for 4.

Intercalary transfer of vascularized bone is best indicated for defect of long bone. Arthrodesis was performed in only one knee joint where reconstruction with prosthesis is usually indicated. In arthroplasty type, remodeling of fibular head was observed. In hybrid type, rapid bone union and low complication rate can be expected when compared to recycling autograft alone. In inlay type, femoral head necrosis even after wide curettage can be prevented.