The management of transarticular fractures is still a difficult clinical problem. Owing to the shape memory effect and its special design,the shape memory com- pression staple could fulfill nearly all the special treatment requirement of the trans- articular fractures.Early bone union and 93.5% satisfactory function restoration were obtained in the series of 121 cases.Stable fixation,early functional exercise and continuous compressive force produced by the staple are the mainofactors contri- buted to the good results.

Objective To i nv estigate the clinical effect of shape-memory sawtooth-arm em bracing fixator in the management of periprosthetic femoral fracture.Methods Since1994, 21cases of periprosthet-ic femoral fractures had been treated in7hospitals with the shape-memory sawtooth-arm embracing fixator designed and developed b y the Ninth Peoples Hospital,Shanghai Second Medical University(SSMU ).Of the21cases,12were males and9were females,aging from42to83years old. Eighteen of the series ex peri-enced periprosthetic fracture at2weeks to10y ears after joint replacement the fractures were found as oblique,spi ral or comminuted with the fracture lines located between the lesser trochanter and a p oint 5cm distal to the end of prosthetic stem.The other three were revision c ases,in which2cases with osteoporosis had intraoperative spiral fracture and1 case had long segmental osteotomy for removal of the prostheses.One of the 21patients had Z-shaped femoral osteotomy,while the other20cases were clas sified into Jo hannson typeⅠfrac ture in4cases,typeⅡ9cases and typeⅢ7case s.All of them were complete fracture with dis-placement.In practice,the arm s of fixator were expanded firstly by immersing into the ice water to make the tempera ture of the device decrease to4~7℃.After reduction of the fracture ,the body of the fixator was placed on the tensile side of the femur,and th e temperature of the arms was raised with hot saline.With its shape memory ef fect,the sawtooth-arms began to close up and grasped the fracture fragments ti ghtly.Results Surgical process in all of the cases was smoothly done:the frac tures were stable after the fixation,and no ex-ternal fixation was required po stoperatively,except four cases underwent skin traction of the affected lim b for 2weeks.All the patients were able to walk with two crutches at2to4we eks after the operation.The post-operative follow-up lasted from1to7years, and no fracture re-displacement was found.The results of frac-ture healing were good while the functional recovery to the pre-operative level was achieved in the all se ries.Conclusion For periprosthetic femoral fracture,shape memo ry sawtooth-arm embracing fixator is a re liable device being implanted easily and offering stable fixation;it should be the treatment method of the first choice.

Objective To observe the expression of platelet-derived growth factor A(PDGF-A) and PDGF-?R in callus during osteoporotic fracture healing and to explore further into the mechanism or effect of PDGF-A and PDGF-?R on osteoporotic fracture healing. Methods The expression and change of PDGF-A and PDGF-?R in different period of osteoporotic fracture healing(5, 7, 14, 28, 42 days) were investigated by means of immunohistochemistry(ABC method). Results There were different cells origin (chondrocyte, osteoblast, osteocyte, vascular endothelial cell, et al) and degree of expression of PDGF-A and PDGF-?R in callus during different period of osteoporotic fracture healing. Conclusion PDGF-A moderates and participates in osteoporotic fracture healing. The decrease of osteoporotic fracture repair capacity may correlate with abnormality of PDGF-A secretion.

Objective To observe the ultrastructural alteration and healing characteristics of osteoporotic fracture, and to elucidate its cellular mode of healing. Methods Eighty female SD rats of 8 months old, which had the weight of 290 to 340 g, were randomized into two groups of 40 each: the osteoporotic fracture model(OPFM) and the common fracture model(CFM). After anesthesia, the bilateral posterior transperitoneal approach was performed in the OPFM group and the bilateral ovaries were removed; and in the CFM group, only the sham operations were performed. Three months later, the fracture of femoral middle shaft were created and fixed with a Kirschner pin through medullary cavity. The callus of each rat was examined by transmission electron microscopy(TEM) and scanning electron microscopy(SEM) in 5 days and 1, 2, 4, 6, 8, 12 and 16 weeks postoperatively. Results TEM showed that the number of chondrocyte in OPFM group was greater, but function was lower than that of CFM group. Volume of collagen secreted by the chondrocyte was less and arranged irregularly during the fracture healing period in OPFM group. Number and function of osteoblasts in OPFM group were lower than that of CFM group. Extracellular collagen was disordered and sparse, but function of osteoclasts in OPFM group was more active than that of CFM group. The SEM showed that the collagen in callus of CFM group was dense and arranged in good order or pyknotic. Conclusion The fracture healing of the osteoporotic fractures is due to the decrease of the osteoblastic formation and the increase of the osteoclastic resorption as well as the poor bony healing quality.

Objective To investigate if the physician's attending could improve the compliance of knee osteoarthritis patients with community exercise therapy.Methods The Questionnaire of Community Rehabilitation of Musculoskeletal Disorder was developed.The knee osteoarthritis patients with or without physicians' attending were surveyed anonymously 3 month after exercise.Results The incidence of compliance in exercise was 87.65% in patients with the physicians' attending,and 70.37% without attending(P<0.05).Conclusion The physicians' attending may improve the compliance of knee osteoarthritis patients in community exercise therapy.

Objective To explore the effects of alendronate on adipogenic differentiation of bone marrow stremal cells (BMSCs) and the role of mitogen-activated protein kinases (MAPK) signal pathway in this process. Methods BMSCs were derived from 9-month-old ovariectomized SD rats and exposed to 0.01, 0.1, 1, 10 μmol/L of alendronate for 2 weeks. The number of BMSCs was counted under light microscope after oil red O staining. The expression of peroxisome proliferators activated receptor-γ, 2 (PPAR-γ2) was measured by RT-PCR. The effect of alendronate on MAPK signal pathway was detected by Western blot. Results After two weeks of induction of BMSCs by alendronate, BMSCs with positive oil red O staining significantly decreased as the increase of the concentration of alendronate (P <0.01), so did the expression of PPAR-γ2. The expression level of PPAR 2 increased when exposing BMSCs to ERK1/2 or JNK specific inhibitors, PD98059 and SP600125 for two weeks. However, the expression level of PPAR 2 decreased when exposing BMSCs to SB203580 (an inhibitor of p38) for two weeks. Condusion Alendronate can inhibit adipogenic differentiation of BMSCs derived from ovariectomized rats in a doso-dependent manner by activating ERK1/2 and JNK rather than p38.

ObjectiveTo study the influence of stress－ relaxation plate on disorganization andrepair of the cortex under the plate. MethodsA washer made of viscoelastic polyethylene was placedbetween the screw and the screw hole of a conventional stainless rigid plate(RP) to form a stress－ relax-ation plate(SRP). Both SRP and RP were applied to the osteotomized New Zealand rabbit tibia, thefracture healing process of either fixing with SRP or RP(control) was put under comparative study bypolarized light microscopy, in situ hybridization of collagen mRNA and immunohistochemistry tech-nique from 2 to 36 weeks postoperatively. ResultsThe study of plated bone remodeling showed thatthe degree of cortex osteoporosis beneath the plate was similar between the SRP and RP group 12 － weekpostoperatively. The organization of the bone structure in the SRP group happened later and milder thanthat of the RP group, and the repair process began 12 weeks after implantation. So the resorption cavi-ties became smaller and the structure of collagen fibers became well oriented along, and the osteoblastslying on the surface of resorption cavities expressed and synthesized type Ⅰ collagen 8 to 12 weeks afterimplantation. The changes above increased significantly in most cavities by 36 weeks. No expression andsynthesis of any kind of collagen could be observed during 12 to 36 weeks after implantation in the RPgroup. ConclusionWithout removal of the bone plate, the SRP fixation not only reduces the degreeof plated bone osteoporosis, but also makes the disorganized bone structure return to normal by the ex-pression and synthesis of type Ⅰ collagen mRNA of osteoblasts lying on the surface of resorption cavities.

Objective To assess the fixation efficiency and biocompatibility of the absorbable high strength poly L lactide (SC PLLA) screws which were designed and made by us through a new material reinforcement process, solid state compression (SC), by investigating the healing and tissue reaction of the rabbits which were given femoral osteotomy and fixed with the screws. Method The right femoral condyles of 12 New Zealand rabbits were first cut off and then fixed with a SC PLLA screw. They were sacrificed at 4, 8, 12, and 36 weeks postoperatively to exam their femurs radiologically and histologically. Results At all the sites of osteotomy was seen obvious formation of bony callus. There were no significant displacements at all the operative sides. Histologically, bony union showed at the site of osteotomy and direct connection between the bone and the implants was observed. Conclusion SC PLLA screws can provide sufficient internal fixation for the load bearing cancellous bone, and possess excellent biocompatibility.

Objective To observe foe microstructure of calcar femorale in young and old people andto investigate its clinical significance. Methods Twelve fresh cadaveric proximal femurs harvested from sixyoung(18~30 years) and six old (over 60 years) adults were used in this study. At first, CT scanning of allproximal femurs were taken. Secondly, the cross section of all calcar femorale were X - rayed and observedunder light microscope and scanning electron microscope. Results The calcar femorale can be divided intothree regions on the cross section. The structure of the medial region is conical bone which unites with medialcortex, and it mainly enhances the strength of the femoral neck. Its middle region is spongy conical bone andits lateral region has become trabecular bone. These two regions can transfer the compressive load that comefrom femoral head to the medial femoral cortex below the lesser trochanter, so they can disperse the load offemoral neck. Severe resorption can occur in the calcar femorale in old people, especially in the lateral region.Conclusion The destruction of three dimensional microstructure and ultra-microstructure of calcar femoralecan result in the decline of its mechanical competence and its ability of load transmission.

Objective To investigate the effects of recombinant human growth hormone on cancellous bone of ovariectomized rats with remarkable bone loss. Methods Six-month old Sprague-Dawley(SD) rats were used to receive low, middle and high doses of recombinant human growth hormone three months after ovariectomy. Bone mineral density and bone histomorphormetry were used to study the alteration of cancellous bone of lumbar vertebrae. Results Recombinant human growth hormone significantly increased bone mineral density and improved the cancellous bone volume and trabecular bone architectures. Conclusion Recombinant human growth hormone can restore the bone loss in ovariectomized rats and improve the trabecular bone architectures. However, its effect is dose related.