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Objective To improve and determine the Medical Standards Directory of the Air Force of People′s Libera-tion Army of China( PLAAF) by analyzing the differences in lumbar spondylolysis and scoliosis between PLAAF and the US Air Force( USAF) .Methods All candidates of flying cadets participating in the final radiographic selection between 2013 and 2015 were chosen.They were judged to be qualified or not according to PLAAF and USAF Medical Standards Directory. Results The average morbility of lumbar spondylolysis and scoliosis in PLAAF was 47%and 30.3%respectively.Arnong those who were eliminated in China,86.0%and 92.5%could be regarded as qualified according to the standard of USAF in 2015.The difference was statistically significant (P<0.01).Conclusion Our selection standards for lumbar spondylol-ysis and scoliosis should be improved based on this study.
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Objective To reveal the difference between the standards for genu varum and genu valgum in the medical standard directory PLA Air Force( PLAAF) for recruitment of flying cadets and those adopted in the United States Air Force ( USAF) , and suggest a method for the reform of our flying cadets recruitment.Methods The rejection rate and comprehe nsive assessment qualification rate of genu varum and genu valgum during physical examinations for recruitment of flying cadets between 2012 and 2015 were analyzed.The different standards for genu varum and genu valgum in PLAAF and USAF flying cadets recruitment were compared and subjected to an empirical study.Results During the final physical examination for selection of flying cadets between 2012 and 2015, only 18 candidates were eliminated because of genu varum and genu valgum, accounting 9.1% of the total eliminated candidates because of orthopadics diseases.Four candidates with genu varum and genu valgum passed the comprehensive assessment in 2014 and 31 in 2015, which accounted for 15%of the candidates with orthopaedics diseases approved by comprehensive assessment.The standards for genu varum and genu valgum in PLAAF were based on morphology while those in the USAF based on the function of knees.According to the USAF medical standard directory, 9 of the candidates rejected because of genu varum and genu valgum were qualified and 9 disqualified.Among the candidates with genu varum and genu valgum approved by comprehensive assessment, 32 were qualified and 3 disqualified.Conclusion The standards for genu varum and genu valgum in PLAAF medical standard directory are of lower accuracy.The standards of USAF should be referred to and the function of knees should be considered in selection of flying cadets.Femur-tibia angle should be measured to improve the morphological standards.
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Objective To improve the selection of flying cadets of the Air Force of People′s Liberation Army of China ( PLAAF) by analyzing the differences of medical identification of lumbar spondylolysis between PLAAF and the US Air Force ( USAF) .Methods Flight crew who had been checked for lumbar spondylolysis during hospitalization at the Air Force General Hospital between 2013 and 2015 were chosen.The results of their medical identification were compaired according to PLAAF and USAF Medical Standards Directory, and their differences and possible reasons were analyzed accordingly.Results The qualified rate of PLAAF was about 85%, which was very close to the standards of USAF, but the difference was not of any statistical significance(P>0.05).Conclusion The standards of our medical identification of lumbar spondylolysis was similar to those of USAF, suggesting that the selection of flying cadets can be improved.
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Objective To analyze the security and effectiveness of the accurate resection and reconstruction of pelvic tumor with computer navigation and to evaluate the feasibility of pelvic ring structure and mechanics reconstruction using finite element analysis.Methors From December 2008 to June 2010,tumor resections assisted by computer navigation technology and pelvic reconstructions with assembly prosthesis designed by finite element analysis were performed in 12 patients with internal hemi-pelvic malignant tumors.There were 8 male and 4 female patients,with the average age of 39.7 years(range,25-53).The malignant tumors involved chondrosarcoma(4 cases),osteosarcoma(2),Ewing sarcoma(2),malignant fibrohistiocytoma(1),and metastatic tumor(3,in which including renal cell carcinoma 1 case,thyroid carcinoma 1,and breast carcinoma 1).According to Enneking staging classification,there were 1 case in Ⅰ A,2 cases in ⅠB,2 cases in Ⅱ A.and 4 cases in Ⅱ B.The local recurrence of tumor and functional results were followed up postoperatively.Results There were no nerves,vessels and pelvic organs injuries intra-operatively.The postoperative X-rays showed that the excised regions were proper to the preoperative schedule and en bloc resections were performed in all patients.All assembly prostheses were in satisfactory position.and the screw fixation was accordance with the finite element biomechanical analysis.All the cases were followed up for average 18.2 months (range,8-26).There were 1 case with local recurrence and pulmonary metastasis,1 case with deep infection,and 1 case with deep vein thrombosis.No prosthesis dislocation,loosening,breaking,and limb length discrepancy occurred in all patients.The average MSTS93 functional score was 70%in all patients at 6 months,and 68 % in 6 patients at 20 months follow.up.Conclusion The resection and reconstruction of pelvic tumor assisted by computer navigation is a safe and effective procedure.The finite element analysis can provide accurate biomechanical guidance to the reconstruction of pelvic ring.
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Objective To investigate the effects of a novel |3 titanium fixation with high strength and low elastic modulus on bone healing of osteoporotic fracture and its effects on stress shielding.Methods Forty female Sprague-Dawley rats were oophorectomized before establishment of femur fracture model.The fracture of left femur was stabilized by titanium alloy pin with high elastic modulus (110 Gpa,high elasticity modulus group) and the fracture of right femur by titanium alloy pin with low elastic modu-lus (30 Gpa, low elasticity modulus group).Six and 12 weeks later, the bone volume (BV) , total vol-ume (TV) and bone volume fraction (BVF) were detected by Micro-CT, and the maximum load was de-tected by biomechanical test.The effects of two titanium alloy pins on formation of bony calluses and me-chanical properties of bones were compared.Results Compared with the low elasticity modulus group, more collagen and bony callus, thicker bone trabeculae and more regular lamellar bone were found in the high elasticity modulus group.In low elasticity modulus group, TV (ROI1) was increased obvious-ly at week 6, with no statistical differences in BV (ROI 1), BV (ROI 2) and maximum load between two groups (P < 0.05).TV and BV in region ROI 1 in the low elasticity modulus group were significantly higher than that in high elasticity modulus group (P < 0.05) , while BV in region ROI 2 in low elasticity modulus group was significantly higher than that in high elasticity modulus group at week 12 postoperative-ly (P<0.05).Biomechnical test indicated that the maximum load in low elasticity modulus group was higher than that in high elasticity modulus group.Conclusions The novel B titanium alloy with high strength and low elastic modulus helps reduce effects of stress shielding, diminish bone resorption, in-crease the fibrous callus formation at the initial phase and improve the quality of bone healing at the later phase.
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This study was undertaken to assess the effect of different surface microtopograph of Ti-Nb-Zr-Sn alloy on the biological behavior and soft tissue integration of rabbits' lacertus fibroblast. The lacertus fibroblasts of Achilles tendon of rabbits were cultured and inoculated on the surface of smooth Ti-flake (control group), and on the surface of sand blast, microgrooves, thread Ti-flakes respectively (3 treatment groups). The cell's growth ratio and attaching status were examined by MTT test and scanning electron microscopy (SEM). The rabbits' lacertus fibroblasts proliferated regularly on the surface of Ti-flakes, and most results of their inter-group comparison showed statistically significant difference (P<0.05), thus indicating the different effects of different surface microtopographs on cell's proliferation; By SEM, the cells were noted to have no obvious directivity on smooth surface; they attached irregularly on the sand blast surface. But in the other two groups, they were oriented regularly along the texture. The cells were almost shuttle-like on the four kinds of surface except for a part of irregular cells on the sand blast surface, and there were plentiful cell-cell junctions. Under high power lens, we found cells with limpid microvilli in the experiment samples. Owing to the cell's fast proliferation and regular attachment in the experiment, we concluded that the regular microgrooved surface was more suitable for meeting the requirement of the soft tissues' physiological function.