RESUMO
Degradable bone implants are designed to foster the complete regeneration of natural tissue after large-scale loss trauma. Polycaprolactone (PCL) and hydroxyapatite (HA) composites are promising scaffold materials with superior mechanical and osteoinductive properties compared to the single materials. However, producing three-dimensional (3D) structures with high HA content as well as tuneable degradability remains a challenge. To address this issue and create homogeneously distributed PCL-nanoHA (nHA) scaffolds with tuneable degradation rates through both PCL molecular weight and nHA concentration, we conducted a detailed characterisation and comparison of a range of PCL-nHA composites across three molecular weight PCLs (14, 45, and 80 kDa) and with nHA content up to 30% w/w. In general, the addition of nHA results in an increase of viscosity for the PCL-nHA composites but has little effect on their compressive modulus. Importantly, we observe that the addition of nHA increases the rate of degradation compared to PCL alone. We show that the 45 and 80 kDa PCL-nHA groups can be fabricated via indirect 3D printing and have homogenously distributed nHA even after fabrication. Finally, the cytocompatibility of the composite materials is evaluated for the 45 and 80 kDa groups, with the results showing no significant change in cell number compared to the control. In conclusion, our analyses unveil several features that are crucial for processing the composite material into a tissue engineered implant.
RESUMO
INTRODUCTION: Clear cell chondrosarcoma is a variant of conventional chondrosarcoma behaving as low grade malignant bone tumor. We reviewed our cases of clear cell chondrosarcoma with the aim to assess the best diagnostic and curative approach to this rare tumor. MATERIALS AND METHODS: We report 18 cases of clear cell chondrosarcoma treated at the authors' institution. Pertinent clinical information, pre and postoperative serum alkaline phosphatase (SAP) level were obtained from the patients charts. Available imaging studies including plain roentgenograms, computed tomography (CT) images (in 6 patients) and magnetic resonance imaging (MRI) images (in 2 patients). RESULTS: Eight cases were firstly treated in other institutions, seven with one or more curettage, while one, presented with pathologic fracture, was treated with repeated osteosynthesis. Of the seven patients treated with curettage, five were referred with local recurrence, the mean time between surgical treatment and local recurrence was 52.2 months (from 12 to 132). The other two patients were curetted out 4 and 1 month before, respectively, and were then referred to us to decide about further treatment after incidental diagnosis. Of these cases, three (37.5%) recurred again after our treatment and two of them presented with late bone metastases. Eight patients were originally treated with wide (six) or marginal (two) surgical margins by us. Among them only one proximal humerus (wide margins) had local recurrence 26 months from the first operation. Two patients underwent curettage in our institution, and one of them had a local recurrence. Pre-operative SAP level were obtained in 17 patients. Among them, 11 patients had high pre-operative SAP level (64.7%) and 6 cases were normal. Post-operative SAP levels were obtained in nine patients. After removal of the tumors; SAP levels decreased to normality in seven of the nine patients with high pre-operative SAP. In the other two patients, although the SAP levels were normal, post-operative SAP levels were decreased. CONCLUSION: Serum alkaline phosphatase can be used as a good tumor marker in diagnosis and follow-up. Due to the occurrence of local recurrences and distant metastasis after curettage, we suggest surgical treatment with "en bloc" resection from the first presentation.
