A modified comprehensive learning particle swarm optimizer and its application in cylindricity error evaluation problem.

Particle swarm optimizer was proposed in 1995, and since then, it has become an extremely popular swarm intelligent algorithm with widespread applications. Many modified versions of it have been developed, in which, comprehensive learning particle swarm optimizer is a very powerful one. In order to enhance its performance further, a local search based on Latin hypercube sampling is combined with it in this work. Due to that a hypercube should become smaller and smaller for better local search ability during the search process, a control method is designed to set the size of the hypercube. Via numerical experiments, it can be observed that the comprehensive learning particle swarm optimizer with the local search based on Latin hypercube sampling has a strong ability on both global and local search. The hybrid algorithm is applied in cylindricity error evaluation problem and it outperforms several other algorithms.

[Computer navigation-guided excision of osteoid osteomas].

OBJECTIVE: To report the experience for the precision osteoid osteoma resection using computer navigation system. METHODS: Between January 2008 and December 2009, 26 surgical resections were performed for 26 patients who had osteoid osteoma with computer navigation system. There were 23 males and 3 females with an average age of 18 years (7 to 35). Tumors were located at femoral shaft 9, femoral trochanter 4, femoral neck 2, tibial shaft 5, metaphysic of proximal tibia 1, acetabulum 2, pubis 1, vertebral appendix 1 and radial shaft 1. Pre-operative X-ray and CT of each patient was performed to confirm the diagnosis. It was carried out intraoperatively the process of CT-based navigation in 4 cases and intraoperative Iso-C three-dimensional navigation in 22 cases. The Navigation System software was Spine Navigation 1.2 in all cases. The Pointer was helpful to localize the lesion and precisely resected the lesion without removal of any excess bone. RESULTS: All the navigation operations were finished successfully with curettage for 12 and En Bloc resection for 14. Bone grafting was made in 21 cases and none in 3 cases. The completely clearance of nidus by intraoperative visual inspection and Pointer confirmation, postoperative X-ray and(or) CT scan was performed in all cases. All cases had histopathology diagnosis of osteoid osteoma and immediate pain relief after surgery. All cases were followed up for 20.6 months averaged (12 to 35 months). No local recurrence and pain relapse occurred. CONCLUSIONS: The navigation system is very helpful for the precision tumor resection of nidus. Especially for the patients with osteoid osteoma located at diaphysis, Intraoperative Iso-C three-dimensional navigation is more useful.

[Clinicopathologic features of primary osteosarcoma in elderly patients].

OBJECTIVE: To study the clinical manifestations, radiologic findings, pathologic diagnosis and differential diagnosis of primary osteosarcoma in elderly patients. METHODS: Twelve cases of primary osteosarcoma occurring in patients older than 60 years were encountered during the period from 1985 to 2010. The clinical manifestations, radiologic features and pathologic findings were studied and the follow-up data were analyzed. RESULTS: The sites of involvement included long bones (number = 7), ilium (number = 1), craniofacial bones (number = 2) and soft tissue (number = 2). Radiologic examination showed a mixture of osteosclerotic and osteolytic lesions in 10 patients, soft tissue lesions with high-density areas in 2 patients and soft tissue lesions with periosteal reaction in 8 patients. Histologically, most cases showed features of conventional osteosarcoma. There were 2 cases of malignant fibrous histiocytoma-like osteosarcoma, 2 cases of chondroblastic osteosarcoma and 1 case of well-differentiated intraosseous osteosarcoma. Immunohistochemical study played little role in pathologic diagnosis. Ten patients had undergone amputation, including one patient who had received adjuvant chemotherapy beforehand. Nine patients had follow-up information available. Three of them died of lung metastasis and 1 died of cardiovascular disease. CONCLUSIONS: Primary osteosarcoma rarely occurs in elderly patients and can easily be missed. Correlation with clinical, radiologic and histologic features is important for arriving at a correct diagnosis.

[Surgical treatment of massive soft tissue sarcoma in the shoulder girdle].

OBJECTIVE: To detect the character of surgical treatment of massive soft tissue sarcoma in the shoulder girdle and analyze the impact factor to the result. METHODS: Seven patients with massive soft tissue sarcoma in the shoulder girdle were treated in our department between 2005 and 2009. There were 4 males and 3 females. All the patients were referred to our hospital after local recurrence post-operatively. The mean age was 43.8 years old (range 14 - 75). The maximum diameter of the tumor varied from 10 to 16 centimeters. All the patients were performed surgery, wide margin in 4 cases and marginal margin in 3 cases. Five were performed tumor resection and reconstruction with latissimus dorsi muscle flap transfer and skin graft. One was reconstructed with advanced skin flap and skin graft. The other one was treated with skin graft. The diagnosis included 3 malignant fibrous histiocytomas, 1 low grade myxoid fibrosarcoma, 1 Primitive neuroectodermal tumor, 1 rhabdomyosarcoma, 1 dermatofibrosarcomas protuberans. The MSTS score system was used to evaluate the shoulder function. RESULTS: Seven patients were followed up with long time. The mean follow up was 29 months (range 10 to 46 months). Two patients suffered local recurrence and one died of pulmonary metastasis 6 months after the second surgery for local recurrence. One patient suffered pulmonary metastasis. The last four patients were disease-free at the end of follow-up. The function of shoulder girdle was satisfactory. The mean MSTS score was 28. CONCLUSIONS: Soft tissue sarcomas in the shoulder girdle are easy to be misdiagnosed and mistreated. Wide surgical margin was the key impact factor to the local recurrence of soft tissue sarcoma in the shoulder girdle. The surgical margin and invasion of the tumor are the key factor to the prognosis. The soft tissue defect after surgery is often reconstructed by muscle flap transfer or skin flap transfer. The latissimus dorsi muscle flap transfer is often used.