Objective To explore the biomechanical difference between the different fixations of cortical bone plate allograft. Methods Twenty-seven cadaveric femurs were harvested and were made into the simulated fracture models, which were equally divided into Groups A, B and C. In Group A, the models were fixed with 2 bone plate allografts (110 mm×10 mm×3 mm); in Group B, the models were fixed with 2 struts (110 mm×10 mm×3 mm) and 5 bone screws; in Group C, the models were fixed with 1 strut (110 mm×10 mm×3 mm) and 5 bone screws. The biomechanical tests for the three-piont bending, torsion, and compression were performed. The parameters studied included the values of the displacements in the three-piont bending tests and the compression tests, and the maximum loads during the bending, the compression, and the torsion. Results As for all the stiffness parameters tested, Group A showed the greatest displacements among the threegroups（P＜0.05）, except the compressive stiffness parameter, which was similar to that in Group B. The maximum loads of the three-point bending, the torsion, and the compression in Group A were 1.65±0.34 kN, 554.3±49.34 N, and 7.78±0.82 Nm, respectively; in Group B, they were 1.12±0.37 kN, 428.00±37.40 N,and 3.39±0.22 Nm, respectively; in Group C, they were 0.71±0.46 kN, 218.67±36.53N, and 1.74±0.12 Nm, respectively. Group A had a significantly greater strengththan the other 2 groups(P＜0.05). Conclusion The strength of the cortical bone plate allograft is related to its different fixations. The two cortical bone plate allografts have a greater strength and stiffness than the struts fixed with the bone screws, which can meet the clinical requirement.
Objective To investigate the preparing procedures for the larger chemically acellular nerve allografts (CANA) and to establish an evaluation criteria and the preparation method.Methods The sciatic nerves ofthe dogs were exposed by a muscle-splitting incision and were isolated free of the underlying fascia. The 50-mm-long segments of the nerve were made. The proximal and distal ends of the nerve segments were labelled and stabilized by pinning the ends to a thin plastic support, and then they were treated according to the following decellularization processes: The nerve segments were rinsed with the distilled water for 9h, transferred in a 3% Triton-100 solution for 12 h, soaked in 7% sodium deoxycholate for 12 h, and washed in the distilled water for 6 h. All the decellularization steps were performed at room temperature. The nerve segments were divided into 5 subgroups. In Group Ⅰ, Group Ⅱ and Group Ⅲ, the nerve segments were decellularized for 2, 3 and 4 times, respectively. In Group Ⅳ and Group Ⅴ, the two ends of the nerve segments were ligated with a silk line and were decellularized for 2 and 3 times, respectively. Each nerve segment was subdivided into 5 portions from the proximal end to the distal end. The degrees of decellularization, activity of Laminin, degrees of demyelination, and integrity of the nerve fiber tube were observed under microscope and were assessed by a scoring system. Results In all the groups the activity of Laminin was present and the degrees of decellularization were complete. As for the demyelination of the nerve segments, the myelin sheath in Groups Ⅰ, Ⅱ and Ⅲ was partially preserved, but it completely disappeared in Groups Ⅳ and Ⅴ. The structure of the nerve fiber tube in Groups Ⅰ and Ⅳ was almost normal. The total score for the degrees of decellularization, demyelination, and structural integrity was the lowest in Group Ⅳ but the quality was the best. Conclusion The degrees of demyelination are not parallel to the times of decellularization processes. In the quality control of CANA, we should consider the following 4 factors: activity of Laminin, degrees of decellularization, demyelination, and structural integrity. For the larger CANA,ligation of the two ends of the nerve segments during the decellularization procedure may be a better method of ensuring the quality of the decellularization.
Objective To investigate the research advance in repair of the peripheral nerve defect with an acellular nerve allograft. Methods The recent related literature was extensively and comprehensively reviewed. The methods and the effects of the allografts with acellular nerves were analyzed. Results The immunogenicity of the allograft was more significantly relieved by the chemical treatment than by the physicaltreatment. The effect of the chemical treatment on the axon regeneration was better than that of the physical treatment. Conclusion Because of the limitation of the host Schwann cell translation in the longsegment acellular nerve allografts, the effect of Schwann cells is not satisfactory and regeneration of the nerve is limited. So, the recellularized treatment with some related measures can enhance the host Schwann cell translation so that this problem can be solved.
OBJECTIVE: To investigate the styles and affecting factors of bone union after massive frozen allografting for skeletal reconstruction owing to excision of bone tumor. METHODS: From 1992 to 1999, 85 patients suffering from bone malignant tumor were given the excision of large bone segment and treated with allografting in different methods of operation: large bone allografts with condylar articular surface in 16 cases, osteoarticular allografts in 57 cases, bone allografts in combination with prosthetic replacement of hip in 9 cases, and prosthetic replacement of knee in 3 cases. The average follow-up was 2 years and 9 months. The union time and styles of host-donor junction were determined by X-ray characters, and the results of operations were assessed according to Enneking’s functional evaluation system of reconstructive procedures after surgical treatment of tumors for the musculoskeletal system. RESULTS: There were 4 kinds of basic bone union styles by the X-ray characters, there were no significant difference in the time span of bone union after fixation with different methods. Of the 85 fresh-frozen allografting procedures, more than 80% of the patients were treated with interlocked intramedullary nail and allograft-prosthesis combination, and the overall result was excellent and good. Sufficient blood supply was important for host-donor junction healing, but the function of immune response was uncertain. CONCLUSION: There were different styles of bone union after massive allografting. The recommended operative methods for massive allografts are stable internal fixation, sufficient blood supply, soft tissue repair and periosteal flap coverage.
Objective To evaluate the shortterm efficacy of osteoarticular allografts in the limb salvage of the proximal tibia. Methods From 1998 to 2003, 15 patients (7 males, 8 females; aged 14-56 yr, average 33) with bone tumor of the proximal tibia underwent osteoarticular allografts, among whom 7 had progressive giant cell tumor without any previous chemotherapy; 8 had malignant tumor with previous chemotherapy, including 6 patients with osteosarocoma, 1 with spindle cell sarcoma, and 1 with malignant fibrous histiocytoma. According to the Enneking system, the patients were classified into ⅠB (7 patients), ⅡA (2 patients), and ⅡB (6 patients). All the patientsunderwent the marginal resection with an allograft (average length 12 cm, range6-16 cm) implanted. Results The follow-up for an average of 21 months (range,3-58 months) revealed that among the 8 patients with malignant tumor of the proximal tibia undergoing chemotherapy, 5 had union of the bone, 3 had no union of the bone; among the 3 patients, 2 had a complication of infection and 1 had a local recurrence. All the 3 patients underwent amputation at the lower part of the femur. According to the Mankin score, 2 patients had a perfect result, 2 good, 1 fair, and 3 poor, with a 50% effectiveness rate. Among the 7 patients with progressive giant cell tumor at the upper part of the tibia, none had infection or local recurrence, but 2 hadnonunion of the bone and 2 had joint instability, aided by the kneeaidingsystem. According to the Mankin score, 3 patients had a perfect result, 2 good,and 2 fair, with a 71% effectiveness rate. Conclusion The osteoarticular allograft of the proximal tibia has many advantages in spite of a relatively highrate of complications, and it is the limb salvage of choicefor the progressivebenign or malignant bone tumors of the proximal tibia.
Objective To investigate the efficacy of freeze-driedcancellous allograft in the treatment of spinal tuberculosis. Methods From January 1999 to August 2004, there were 31 cases of spinal tuberculosis who underwent surgery. The freeze-dried cancellous allograft was used as grafting material in all the cases.The cancellous allograft was packed in a titanium mesh cage or an artificial vertebrae, and then used as a strut graft anteriorly to implant into the bone defect after the redical debridement, and the instrumentation was done. Results Twenty-three cases were followed up 1.5 years to 5 years (3.7 years on average), and bonyfusion was achieved in 21 cases 6 months later. In 2 cases ceasing antituberculous therapy after 2 months of operation, the local recurrence was obvious. The loosened screw was noticed in one of these two cases, who had tuberculosis in lumbar spine. When antituberculous therapy continued, the bony fusion was observed in these two cases 12 months later. No further position change of the instrument wasnoticed in the patient carrying loosened screw, but the kyphosis of the thoracolumbar spine aggravated. Conclusion Freeze-dried cancellous allograft could be usedin the treatment of spinal tuberculosis. To achieve good results of allograft incorporation and remodeling, the rigid instrumentation should be performed, postoperative antituberculous therapy is also important.
Objective To investigate the clinical effects of repairing massive bone defects in limbs by using vascularized free fibular autograft compoundingmassive bone allografts. Methods From January 2001 to December 2003, large bone defects in 19 patients (11 men and 8 women, aging from 6 to 35 years) were repaired by vascularized free fibular transplant with a monitoringflap compounding massive deep frozen bone allografts. The length of bone defects were 12 to 25 cm (16.6 cm on average), of vascularized free fibular 15 to 28 cm (18.3 cm on average), and of massive bone allografts 11 to 24 cm (16.1 cm on average). Thelocation of massive bone defects were humerus in 1 case, femur in 9 cases and tibia in 9 cases. Results After followup of 5 to 36 onths (18.2 months on average), wounds of donor and recipient sites were healed at Ⅰstage, monitoringflaps were alive, no obvious eject reaction of massive bone allografts was observed and no complications occurred in donor limbs. The radiographic evidence showed union in 15 patients 3 months and 3 patients 8 months after operation. One case of malignant synovioma of left lower femur recurred and amputation was performed 2.5 months after surgery. Internal fixation was removed in 5 patients, and complete bone unions werefound 1 year postoperatively. No massive bone allografts was absorbed or collapsed. Conclusion With strict indication, vascularized free fibular autograft compounding massive bone allografts, as an excellent method of repairing massive bone defects in limbs, can not only accelerate bone union but also activate and changer the final results of massive bone allografts from failure.
Objective To explore the effect of tri pterygium glycoside (TG) on the skeletal muscle atrophy and apoptosis after nerve allograft. Methods Twenty Wistar male rats were adopted as donors, weighing 200-250 g, and the sciatic nerves were harvested. Fifty SD male rats were adopted as recipients, weighing 200-250 g. Fifty SD rats were made the models of10 mm right sciatic nerve defect randomly divided into five groups (n=10): group A, group B, group C, group D and group E.groups A and B received fresh nerve allograft, groups C and D received sciatic nerve allograft pretreated with TG, and group E received autograft. The SD rats were given medicine for 5 weeks from the second day after the transplantation: groups A and E were given physiological sal ine, groups B and D TG 5 mg/ (kg·d), and group C TG 2.5 mg/ (kg·d). At 3 and 6 weeks, respectively, after nerve transplantation, general observation was performed; the structure of skeletal muscles was observed by HE staining; the diameter of skeletal muscles was analyzed with Image-Pro Plus v5.2; the ultrastructure of skeletal muscles was observed by TEM; the expressions of Bax and Bcl-2 were detected by immunohistochemical staining; and the apoptosis of skeletal muscles was detected by TUNEL. Results All rats survived to the end of the experiment. In general observation, the skeletal muscles of SD rates atrophied to different degrees 3 weeks after operation. The muscular atrophy in group A was more serious at 6 weeks, and that in the other groups improved. The wet weight, fiber diameter and expression of Bcl-2 in group A were significantly lower than those in groups B, C, D and E (P lt; 0.01)；those in groups B, C and D were lower than those in group E (P lt; 0.05); and there were no significant differences among groups B, C and D (P gt; 0.05). The apoptosis index and expression of Bax in group A were significantly higher than those in groups B, C, D and E (P lt; 0.01)；those in groups B, C and D were higher than in groupE (Plt; 0.05); and there were no significant differences among groups B, C and D (P gt; 0.05). Three weeks after nerve allograft, under the l ight microscope, the muscle fibers became thin; under the TEM, the sarcoplasmic reticulum was expanded. Six weeks after nerve allograft, under the l ight microscope, the gap of the muscle fibers in group A was found to broaden and connective tissue hyperplasia occurred obviously; under the TEM, sarcomere damage, serious silk dissolution and fragmentary Z l ines were seen in group A, but the myofibrils were arranged tidily in the other groups, and the l ight band, dark band and sarcomere were clear. Conclusion TG can decrease the skeletal muscle atrophy and apoptosis after nerve allograft. The donor’s nerve that is pretreated with TG can reduce the dosage of immunosuppressant for the recipient after allograft.
Objective To study and summarize the clinical experience and significance of the skeleton reconstruction of human hand allografts. Methods From January 2001 to October 2003, human hand allografts were appliedto treat 4 cases of traumatic hand defect(6 hands) at different levels. During operation, the ulna and radius were reduced anatomically and fixed firmly with 3.5 mm AO-plates and screws according to AO internal fixation principle. The X-ray films were taken periodically andthe function recovery of hand allografts was observed and estimated. Results The 4 cases were followed up for 4-36 months postoperatively. The clinical healing of fracture in 4 cases(6 hands) was achieved after 9 weeks,and by means of comprehensive assessment including the joint function, muscle strength, sensation, appearance, sequela and the ability of work, the satisfactory effects were gained eventually. Conclusion It is significant forhuman hand allografts to reconstruct skeleton firmly.
Objective To study the migration of Schwann cells from the nerve autograft in the acellular nerve allograft of the rats in vivo. Mehtods The sciatic nerves (20 mm long) of the SD rats were harvested and prepared for the acellular nerve grafts by the chemical extraction. Then, they were observed by the gross view, HE staining, and Antilamininstaining, respectively. Another 32 female SD rats weighing 250-300 g were obtained for the study. A 2-mm-long nerve autograft was interposed between the two 10-mm-long nerve allografts to form a 22-mm-long composite. Then, the composite was placed in the muscle space, together with a sole 22-mm-long nerve allograftas a control. They were harvested at 5，10，15 and 20 days, respectively, and were then given the HE staining and the S-100 staining. Results The acellular nerve graft was semitransparent under the gross view. HE staining showed that no cell was observed within the nerve graft. Anti-laminin staining showed that the basal membrane was partially interrupted, with a positive result (dark brown). All the nerve grafts in both the groups exhibited the existenceof the cells. The S-100 positive cells were observed from the 15th day at the far ends of the two allografts of the composite; however, there were no suchcells observed within the sole nerve allograft. Conclusion Schwann cells from the sciatic nerves (2 mm- long) of the rats can migrate in the acellular nerve allograft to the far ends of the neighboring 10-mm-long nerve allografts at 15 days after operation, which offers the theoretical basis forthe repair of the longrange nerve defect by the composite of the acellular nerve allografts with the interposed nerve autograft.