OBJECTIVE: To investigate the biological behavior of classical and atypical osteoblastomas in comparison to osteosarcomas. METHODS: Based on histological parameters, 30 osteoblastomas were subclassified as classical osteoblastomas (23/30) or atypical osteoblastoma (high cellularity, prominent blue osteoid, and epithelioid osteoblasts-7/30). Comparative immunohistochemical and clinical analysis was performed in 17 cases of patients with high-grade osteosarcoma. Formalin-fixed, paraffin-embedded archival tissue was immunostained for p53 and proliferation cell nuclear antigen. Tumors with positive p53 stain underwent molecular analyses for fragments of exon 10. RESULTS: The mean proliferating cell nuclear antigen indexes for classical osteoblastoma, atypical osteoblastoma, and osteosarcoma were 33%, 61%, and 79%, respectively. The atypical subgroup showed similar results to those of the osteosarcoma group (P < 0.001). p53 protein was detected in 4 (13%) osteoblastomas (3 of these were atypical osteoblastoma), and 4 osteosarcomas (23%) also showed p53 positivity. DNA mutation performed in p53-positive cases was confirmed in exon 10 in 2 atypical osteoblastomas (2/3), 1 classical osteoblastoma (1/1), and 1 osteosarcoma (1/4). Disease recurrence was correlated with p53 expression (P = 0.009), atypical subtype (P = 0.031), spiculated blue bone on histology (P = 0.018), and proliferating cell nuclear antigen labeling index ≥ 40 (P = 0.015). CONCLUSION: These results validate atypical osteoblastoma as an entity, with p53 and proliferation cell nuclear antigen immunoexpression closer to that of osteosarcoma than of classical osteoblastoma. Proliferating cell nuclear antigen labeling index and p53 may be useful predictors of recurrence.

PURPOSE:To evaluate the effect of a local application of simvastatin gel in repairing bone defects in the femurs of rabbits. METHODS:Two standard surgical cavities were created in the femoral epiphysis of 18 rabbits. In the simvastatin group (SG), the cavities were filled with a collagen sponge soaked in 0.5 ml of a simvastatin (1 mg) gel, and the cavities were covered with a biological membrane. The bone cavities in the second group (control group) were filled with a blood clot and covered with a biological membrane.On the 7 th, 21st and 42 nd days, six animals in each group were euthanized, and the femurs were subject to histological evaluation (vascularity, fibrosis, reactive bone formation, osteoblasts, and osteoclasts) and immunohistochemical (anti-VEGF and anti-osteocalcin) analysis.The results were analyzed using a Wilcoxon test (p<0.05). RESULTS:There were significant differences between the two groups: the SG had greater scores in comparison with the CG in terms of the degree of vascularity on the 7t h and the 21st days, fibrosis on the 21 st day, bone formation reaction on the 21 st and the 42 nd days and the number of osteoblasts and osteoclasts on the 42 nd day. The immunohistochemical expression was also greater for osteocalcin and VEGF on the 7 th, 21st and 42 nd days. CONCLUSION:Surgical defects created in rabbit femurs were treated locally with simvastatin gel to stimulate bone repair, which promoted an ameliorative effect in the morphological and immunohistochemical markers of bone regeneration.

CONTEXT AND OBJECTIVE: The development of a slow and progressive mechanical model for osteoarthritis is important for correlation with clinical practice, and for evaluating the effects of disease-modifying medications. A mechanical osteoarthritis model was developed to evaluate the effects of intra-articular hyaluronic acid (HA) injection and oral diacerein administration. DESIGN AND SETTING: Experimental study at the Department of Orthopedics and Traumatology, Universidade de São Paulo. METHOD: Total medial meniscectomy was performed on seven groups of ten Wistar rats each, comprising four control groups (C) and three study groups (S). C.I: operated, non-medicated; C.II: operated, injections of HA vehicle; C.III: non-operated, non-medicated; C.IV: operated, non-medicated, sacrificed three months post-meniscectomy; S.I: operated, receiving intra-articular HA injections; S.II: operated, oral diacerein from the third to the seventh postoperative month; S.III: operated, received both medications. All the animals (except C.IV) were sacrificed seven months post-meniscectomy. All femurs and tibias were assessed histologically. RESULTS: The most severe degenerative histological changes were in the tibias of the operated knees. On the contralateral side, all groups had mild changes on the tibial surface. The femoral surface had slight changes. C.I showed severe changes. S.II results matched those of C.IV. HA protected the tibial surface. S.II and S.III had similar results. CONCLUSIONS: 1) The experimental model produced mild arthritis after three months and severe arthritis after seven months; 2) diacerein reduced the degenerative changes in both knees; 3) HA protected the joint cartilage; 4) Combining the two drugs did not improve the results.RESUMO CONTEXTO E OBJETIVO: Desenvolver um modelo osteoartrítico mecânico lento e progressivo é importante para correlação com a prática clínica e para avaliar os efeitos de medicamentos modificadores da doença. Um modelo mecânico de osteartrite foi desenvolvido para avaliar os efeitos de injeção intra-articular de hialuronato de sódio (AH) e de administração de diacereína oral. DESENHO E LOCAL: Estudo experimental no Departamento de Ortopedia e Traumatologia, Universidade de São Paulo. MÉTODO: Meniscectomia medial total foi feita em sete grupos de dez ratos Wistar, sendo quatro grupos controle (C) e três grupos estudo (E). C.I: operado, não medicado; C.II: operado, recebendo injeções do veículo do AH; C.III: não operado, não medicado; C.IV: operado, não medicado, sacrificado três meses pós-meniscectomia; EI: operado, recebendo injeções de AH intra-articular; E.II: operado, recebendo diacereína oral do terceiro ao sétimo mês pós-operatório; E.III: operado, recebeu ambas medicações. Todos os animais (exceto C.IV) foram sacrificados sete meses pós-meniscectomia. Todos os fêmures e tíbias foram analisados histologicamente. RESULTADOS: As alterações histológicas degenerativas mais graves encontram-se nas tíbias dos joelhos operados. No lado contra-lateral, todos os grupos apre...

Objective: To present a series of 50 consecutive patients with non-metastatic extremity osteosarcoma, and attempt to correlate expression of the vascular endothelial growth factor (VEGF) protein in biopsy tissue to their prognosis regarding overall survival, disease-free survival and local recurrence. Methods: Fifty cases of non-metastatic osteosarcoma of the extremities treated between 1986 and 2006 at Instituto de Ortopedia e Traumatologia da Universidade de São Paulo, São Paulo, Brasil, were evaluated regarding expression of the VEGF protein. There were 19 females and 31 males. The mean age was 16 years old (range 5-28 years old) and the mean follow-up was 60.6 months (range 25-167 months). The variables studied were age, gender, anatomic location, type of surgery, surgical margins, tumor size, post chemotherapy necrosis, local recurrence, pulmonary metastasis and death. Results: Thirty-six patients showed VEGF expression on 30% or less cells (low), and the remaining 14 cases had VEGF expression above 30% (high). Among the 36 patients with low VEGF expression, nine developed pulmonary metastasis and four died (11.1%). Among the 14 patients with high VEGF expression, six developed pulmonary metastasis and three died (21.4%). Conclusion: There was no statistically significant correlation between the expression of VEGF and any of the variables studied. Level of Evidence IV, Therapeutic Study.

SUMMARyGiant Cell Tumor (GCT) is a benign tumor, with a recurrence rate of about 20% -34% of the cases. It is usually located at long bone epiphysis. The objective of this study is to report a GCT case in a vertebra, which was early diagnosed as Aneurysmal Bone Cyst (ABC), and to discuss potential differential diagnosis, correlating them to patterns shown on imaging tests. This patient is a 37 year-old female, with clinical picture of pain in spine and paraparesis that started two months earlier.An early diagnosis of ACB was delivered. At X-ray, the injury was lithic, with erosion and cortical destruction. Tomography and resonance showed a cystic and hemorrhagic injury, extending to soft parts. Slides review and the analysis of dried surgical matter submitted to HE and immunohistochemical staining with p53 marker allowed for GCT diagnosis. Many benign lesions present with multi-nucleated giant cells. Imaging tests not always enable a conclusive diagnosis. A definite GCT diagnosis depends on anatomicopathological test, with careful evaluation of the stromal component and positive immunoexpression for p53 protein. Treatment is delivered as surgical resection, with wide margins, followed by instrumentation in cases of tumors located at spine.