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 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 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 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 investigate the rejection mechanisms of bone grafts by comparing the immune reaction of xenografts versus allografts, and the influence of IL-4 and IL-10 on immune responses. Methods Twenty C57BL/6 mice and 1 New Zealand rabbit were used as transplant donors for allografts and xenografts, respectively. One hundred BALB/c mice were used as transplant recipients and randomly divided into 5 groups. Using a model of the muscle pouch for implantation, the immune reactions of bone allografts and bone xenografts were studied through observing the lymphocyte responses of the stimulating index of lymphocytes from the mixed lymphocyte culture (MLC), subsets of lymphocyte, cytokinetic and histological findings in 1, 2, 4 and 6 weeks after implantation respectively. Results Xenograft rejection was rapid (1 week) and stronger than allograft rejection (P

Objective To summarize the experience in CAD / CAM custom-made hemipelvic prosthesis and its application in 8 patients. Methods The exact model of pelvis was generated with its CT data by Rapid Prototyping Technique (RPT). Simulated bone resection and prosthesis design were performed on the models. The prosthesis should be fixed simultaneously on the contralateral pubic ramus (or the remainder of pubis), the joint facet of sacrum (or the remainder of ilium) and on the remained ischium if part of it could be preserved. When prosthesis was put in place, the acetabular component should be symmetric with the contralateral acetabulum in terms of the height, lateral distance and abduction angle, after it's fixation on the remained pelvis with cancellous screws, bolts and hooks, conventional total hip implants with cemented acetabular and cementless femoral prothesis were implanted. 8 patients underwent this kind of procedure, of them 7 suffered from large pelvic tumor, including 2 chondrosarcoma, 3 giant cell tumors, 1 cartilaginous fibrodysplasia and 1 metastasis. One patient received this procedure for severe osteolysis after THA. Tumor artery embolization was done in 6 of them 24-48 h before operation. Results Blood transfusion was 4971 ml in average. The implantation of prosthesis was easily accessible. One suffered from remained sinus, and healed after myocutaneous flap transferring. All patients began non-weight bearing walk with double crutches 6 weeks after operation and gradually abandoned crutches in 3 months. One patient with chondrosarcoma died of lung metastasis 9 months after operation. No loosening was found during the 1 to 4 years (2.5 years in average) follow-up of the 7 cases. The position of bilateral hips was symmetric. They all recovered to self-care. Two of them returned to work 7 and 8 months after operation respectively. One local recurrence happened and was resected again. Conclusion The custom-made hemipelvic prosthesis generated with RPT and CAD/CAM can improve the prosthesis fixation, ensure the exact orientation of acetabular component and make the operation easy.

[Objective]To observe the effect of sciatic nerve and femoral nerve resection on heterotopic osteogenesis induced by recombined human bone morphogenetic protein-2(rhBMP-2) and discuss role of never innervation on bone regeneration and partial reasons for larger callus after bone fracture accompanying denervation.[Method]A total of 36 male ICR mice were divided into experimental group and control group at random.0.125mg rhBMP-2 /collagen composites were implanted into the right thigh muscle pouches after sciatic nerve and femoral nerve section in the experimental group and after sham operation in the control group.On the 7~(th),14~(th) and 21~(st) day after implantation,roentgenographic,biochemical,histological analyses and osteoclasts TRAP staining were performed to detect the effects of sciatic nerve and femoral nerve resection on bone growth initiated by rhBMP-2.[Result]On the 7~(th),14~(th) and 21~(st) day,wet weight of new bony tissues of the experimental group was obviously greater than that of the control group.Radiography showed range of bone formation in the experimental group was larger than that in the control,but density of new bone was lower than that of the latter.Biochemical detection showed value of AKP of the experimental group was significantly higher than that of the control on the 7~(th) day,while the content of Ca of the experimental group was higher than that of the control on the 14~(th) day and the content of Ca and P of the experimental group was lower than that of the control on the 21~(st) day.Histological observation showed area of new bone of the experimental group was greater than that of the control,but trabecular bone of the former was sparser than that of the latter.Image analysis of bony tissue showed the relative number of osteoclasts in the experimental group became higher on the 21~(st) day,while volume density and width of bone trabecula in the experimental group were lower than that of the control group.TRAP staining showed osteoclasts in the new bone of the experimental group were more activated than that of the control.[Conclusion]Nerve section results in enhancement of ability of bone regeneration by BMP in the early period,but trabecular bone becomes sparse in the middle and later period because of bone resorption by osteoclasts,which indicates nerve in nervation influences bone regemeration though direct and/or indirect way.

[Objective]To identify the expression of neurotrophic factors(NTFs)and their high affinity receptors(Trk)during the bone induction by recombined human bone morphogenetic protein-2(rhBMP-2)and discuss possible roles of NTFs on the osteoinductive activity of BMP.[Method]After a total of 36 ICR mice were divided into experimental group and control group at random,rhBMP-2/collagen sponge and collagen sponge were implanted into the right thigh muscle pouches of two groups respectively.Tissues in the implanted sites of two groups were removed on the 7~(th),14~(th) and 21~(st) day after implantation.Histological,immunohistochemical and RT-PCR analyses were performed to detect osteoinductive effect of rhBMP-2 and the expression of NTFs and Trk.[Result]RhBMP-2/collagen sponge displayed a potent ability inducing bone formation,while the expression of NTFs and Trk was observed in the course of osteoinduction by rhBMP-2.Especially on the 7~(th) day in the experimental group,NGF and TrkA positive immunostaining reached the peak in the stage of chondrogenesis,including chondroblasts,chondrocytes,hypertrophic chondrocytes and osteoblasts,then decreased in the number of positive cells and the intensity of immunostaining on the 14~(th) and 21~(st) day.BDNF was only observed in chondrocytes and cartilage matrix,and TrkB was expressed in chondroblasts and chondrocytes at the 7~(th) day after implantation.Expression of NT-3 was similar to that of NGF,while TrkC was expressed in chondroblasts and chondrocytes on day 7.Expression level of the mRNA of NTFs peaked at 7 days after the implantation,then decreased,which was nearly coincident with immunohistochemical results.[Conclusion]Many different kinds of cells are induced by rhBMP-2 express NTFs and Trk,which suggests that NTFs may play an important role in the osteogenesis initiated by BMP through direct and indirect pathways.

Objective In order to meet the quantitative measurement of soft tissues balance required in the TKR,a new soft tissues balance navigation system have been developed and used experimentally in adjusting the soft tissue release of medial collateral ligament(MCL)and quantitative measurement of the force change in extension gap or flexion gap after various kinds of MCL release during TKA.Methods Six precise load sensors have been embedded in the front measure device,which is inserted into the cutting gaps of the 5 knee joints of cadavers to measure the force of MCL before or after various types of releases.The device has the function of changing distance between its upper and lower plates by the mechanical structure for the adjustment of different bone cutting space.The reading of the sensors representing the force are displayed in three or two-dimensional manner in real-time with accuracy of better than 0.098 N per bit.Results The preliminary test shows that the measurement system can accomplish the force measurement and the distance adjustment in the knee joint,and its application for measuring the force of medial collateral ligament shows a quantitative force change in MCL in different knee position and different way of release.Release of the posterior portion of MCL mainly produces laxity of MCL at full extension with 33.61% reduction rate of tensional force in value.Complete medial collateral ligament release causes laxity of MCL both at full extension and 90? flexion with reduction rate of 44.96% or 41.30% respectively.Conclusion The soft tissues balance measurement device are capable of clinical use for navigation of soft tissue balance in TKA and performing knee dynamics research.It has been proved quantitatively that the posterior portion of MCL plays an important role in stability for extended knee while the anterior portion of MCL mainly stabilizes the knee in flexion.