Estudo biomecânico comparativo da resistência de segmentos ósseos de rádios de cães autoclavados ou desvitalizados em nitrogênio líquido / Biomechanical comparative study of the strength of bone segments from the radius of dogs autoclaved and devitalized in liquid nitrogen

O presente estudo comparou, por meio do ensaio de flexão em quatro pontos, a resistência de segmentos de rádios de cães autoclavados e desvitalizados em nitrogênio líquido. Avaliaram-se 40 rádios, que foram divididos em quatro grupos: grupo autoclave (GA), grupo controle autoclave (GCA), grupo nitrogênio (GN) e grupo controle nitrogênio (GCN). Os corpos de prova dos grupos GCA e GCN pertenciam ao lado contralateral dos grupos GA e GN, respectivamente. Os ossos foram autoclavados a 121°C, por 20min a 2atm. A desvitalização em nitrogênio foi realizada por meio da imersão em nitrogênio líquido, por 20min, seguida de descongelamento à temperatura ambiente, sendo finalizada por imersão em solução de NaCL a 0,9%, por mais 15min. Após os testes biomecânicos, foram comparadas as variáveis força máxima, rigidez, altura máxima à secção transversa do corpo de prova, deslocamento do baricentro em relação ao eixo x, flecha, tensão-tração, tensão-compressão e tensão máxima. Não foram encontradas diferenças estatisticamente significantes entre os grupos GN e GCN. Foram encontradas diferenças estatisticamente significantes entre os grupos GA e GCA somente na comparação da variável força máxima. A análise das variáveis tensão-tração, tensão-compressão e tensão máxima evidenciou diferenças estatisticamente significantes entre os grupos GA e GN, sendo os valores maiores para o grupo GA. Também foi realizada comparação entre os deltas (GN menos GCN e GA menos GCA), em que não foram observadas diferenças estatísticas.(AU)

The study compared through the four points bending test, the strength of bone segments autoclaved and devitalized in liquid nitrogen radius segments. 40 radius were used, collected and divided into 4 groups, as follows: Autoclave Group (GA), Control Autoclave Group (GCA), Nitrogen Group (NG) and Control Nitrogen Group (GCN). Bone segments from groups GCA and GCN were contralateral to GA and NG. The segments were autoclaved at 121ºC and 2 atm for 20 minutes. Nitrogen devitalization of the bone segments was obtained by 20 minutes immersion, followed by thawing at room temperature and 15 minutes immersion in 0.9% NaCL solution. After biomechanical tests the variables compared were maximum strength, stiffness, maximum hight trough the transverse section of the bone segment, centers of mass dislocation in relation to x axe, arrow, stress-tension, stress-compression and maximum stress. No statistically significant differences between the GN and GCN groups were found. Statistically significant differences were found between GA and GCA groups only in the comparison of the maximum force variable. The analysis of variable stress-tension, stress-compression and maximum stress showed statistically significant differences between the GA and GN groups, with higher values for the GA group. Comparison of the deltas (GN least GCN and GA least GCA) where no statistical differences were observed was also performed.(AU)

Reconstruction Options after Surgical Resection in Muskuloskeletal Tumors of the Extremity / 대한정형외과학회잡지

Recently limb sparing surgery is accepted as an alternative method in the management of muskuloskeletal tumors of the extremity without undue compromise to the patient s life. But the limb sparing procedure results in large osseous and soft tissue defects. To fill these defect, several options have been used such as tumor prosthesis, temporary spacer with cementation, allograft, and autograft(fresh, autoclaved, low heat treated, and extracorporeal irradiated). To identify the indica- tions ot' individual option, we studied 66 cases of musuloskeletal tumors of extremity which were treated with wide or marginal resection and reconstructive surgery from June, 1990 to June, 1997, in which 48 cases were osteosarcomas, 3 chondrosarcomas, 2 synovial sarcomas. I liposarcoma, 1 giant cell tumor, I malignant lymphoma, and 10 metastatic bone tumors. The location of the lesion were distal femur in 24, proximal tibia in 24, proximal femur in 9, proximal humerus in 6, tibial midshaft in 1. distal radius in 1, and calcaneus in 1. In Enneking stages about primary bone tumors 6 cases were IIA, 42 IIB, and 8 III. We reconstructed the osseous defect with tumor prosthesis in 22 cases, temporary spacer in 9(later, 4 cases was changed to tumor prosthesis for staged operation), allograft in 25, and autograft in 14(low heat treated in 2, irradiated in 12). Total functional result by Enneking system was 71.5% . 80.8% with tumor prosthesis, 50.5% with temporary spacer, 70% with allograft, 75.3% with autograft. Infections were occurred in 18% of the patients treated with tumor prosthesis, 34% with allograft, 0% with temporary spacer or low heated autograft, and 18% with irradiated autograft. Delayed union or nonunion was occurred in l5% of the patients treated with allograft, 40% with autograft. There were 2 cases of metal failure and 2 cases of graft fracture using autograft. In conclusion, we propose that the indication of the tumor prosthesis is for the skeletally matured patient, patient with high-grade malignant tumor, older patients, and patient who have limited life expectancy. The reconstruction with allograft have several advantages for the patients with henign bone tumor and locally aggressive or low-grade malignant tumor. The temporary spacer may be used as staged operations for the skeletally immature patient and patient who have an extreme hone and soft tissue defects after limb sparing operation. The recycling autograft may be applied to the patients at any age with minimal bony involvement of tumor. The low heat treated autograft may be useful in the patients requiring intercalary reconstruction, and the irradiated autograft may he useful in the patients with periarticular involvement.

Limb / 대한정형외과학회잡지

Tumors involving the proximal humerus confront the surgeon with the problem of both eradicating the osseous lesions and restoring shoulder joint function. This problem is magnified because of the biomechanical complexity of the shoulder, its anatomic configuration, and its inherent lack of stabillity. With the increased interest in limb-sparing resection for lesions in the area, efforts are being made to improve the reconstructive techniques. These include leaving a flail shoulder, an being made to improve the reconstructive techniques. These include leaving a flail shoulder, an arthrodesis using intercalery graft between the scapula and the remaining humerus, or if the glenoid is preserved, an arthroplasy. From January 1984 to December 1993, 23 patients with a malignant or locally aggressive bone tumor in the proximal humerus were treated by limb-sparing surgery in Seoul National University Hospital. Histologic diagnosis included osteosarcoma(6), chondrosarcoma(2), Ewing's sarcoma(1), metastatic bone tumor(11), and recurred giant cell tumor(3). Options for reconstruction following limb-sparing resection in our cases were 10 prosthetic arthroplasties, 3 arthrodeses with an living fibula graft, and 10 arthroplasties with intramedullary nailing and cementization. We performed a retrospective analysis in view of tumor eradication and performance status with modified functional evaluation system of Musculoskeletal tumor Society. In 7 cases(74%), good or fair performance status was acquired with average 3.6 years follow-up(6 months-11 years). Each option for reconstruction resulted in relatively good outcome but rather better result was acquired in giant cell tumor and chondrosarcoma. Estimated survival rates by Kaplan-Meier's method, 5 year survival rate was 81% in primary malignant bone tumors(12), 76% in stage Ⅱ B malignancies(5) with 4 years and 4 months follow-up. There was no regional recurrence in primary malignant bone tumors but there were three cases in which distant pulmonary metastases were found in follow-up. Complicationss were one soft tissue infection, two nonunions in arthrodesis with a living fibula graft and one dislodgement of prosthesis in prosthetic arthroplasty. In summary, each option for limb-sparing surgery in malignant bone tumor of proximal humerus might result in rather satisfactory outcome in performance and survival rate when effective preoperative and postoperative chemotherapy were performed in adequately selected cases.