Three-dimensional finite element analysis and biomechanical study on reconstruction of the large defect of proximal femur with allograft prosthesis composite in clinical bone-healing phase / 生物医学工程学杂志

Three-dimensional finite element models of the large defect of proximal femur were reconstructed with allograft prosthesis composite in clinical bone-healing phase; current model was under the given conditions of 138mm-intramedullary stem-length of host bone and 135mm defect-length of proximal femur. The femur was constructed with efilm software from CT data, then three-dimensional concrete models were created by using Proe-Wildfire software; the three-dimensional finite element models of allograft prosthesis composite were made in ANSYS11 software. Loads were simulated using the peaking values during stance walking. The stress on femur-cement-callus-prostheses and the influence of stress on the clinical bone-healing phase were analysed. The highest stress value of femur is on the medial side of the tip of the prostheses. The highest stress value of cement mantle is on the medical side of the cement mantle at the tip of the stem. The highest stress value of the prostheses is on the medial side near the upper 4cm of the stem tip. The highest stress value on the callus is at the medial side of the callus layer. The highest stress value on every part is under the corresponding fatigue strength. Clinical bone-healing phase model is well enough for stance walking.

Surgical treatment of fibrous dysplasia of bone involving the femur with severe varus deformity / 中国矫形外科杂志

[Objective]To find an effective method of surgical treatment of fibrous dysplasia of bone involving the femur associated with severe varus deformity.[Method]Thirteen patients with fibrous dysplasia of bone involving 14 femurs with severe varus deformity were reviewed from Feb 2002 and Jul 2005.Medial displacement of valgus or valgus osteotomies,curettage and allograft,reconstructional nail have been adolted to treat fibrous dysplasia of bone involving the femur with severe varus deformity.[Result]All patients were followed up from 8 months to 41 months with an average of 21 months.Forteen femoral mechanical alignments(axis)had been corrected completely rdiologically;the preoperative average neck-shaft angle of 75?(range,55?~100?),corrected to the average 120?(range,95 ?~135?)of postoperative,the average shortening of the femur was 3.4 cm(range,2.0~4.5 cm)preoperatively,then enlongthened by 2.8 cm(range,1.8~3.6 cm)in postoperation.Ninteen location of osteotomies showed good union in 14 femur.All bone grafts were absorbed slightly beginning at 3 months and markedly at 10 to 14 months postoperatively.Preoperation,4 patients walked with bilateral crutches,2 used unilateral cane,5 can't walk due to pathological fracture,2 without support;after operation,11 patients walk without support,2 ambulated with the aid of unilateracane.Eleven patients were painless,2 moderate pain.All had no infections and recurrent fracture and progression of the deformity.[Conclusion](1)This method can correct varus deformity,improve function,as well as restore biomechanical axis of femur.(2)It is able to effectively eradicate lesions and prevent recurrence.(3)Impaction allograft is the key of prompting allograft incorporating fully and preventing pathological fracture.