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BACKGROUND:Nano bone putty and bone cement injection are two common methods to strengthen the fixation of pedicle screws, but there are relatively few reports on the comparison of their strengthening effects. OBJECTIVE:To compare the biomechanical characteristics of bone cement and nano bone putty strengthening pedicle screw implantation in the fixation of osteoporotic vertebral body. METHODS: Totaly 24 human cadaveric pedicles were obtained, which were al in line with osteoporosis standards, and randomly divided into 3 groups: control group (only implanted pedicle screws), bone cement group (first injected bone cement in the nail channel, and then implanted pedicle screws) and nano bone putty group (first injected nano bone putty in the nail channel, and then implanted pedicle screws). After 2 hours of implantation, the maximum axial pulout strength and the maximum rotation torque of specimens in each group were determined. RESULTS AND CONCLUSION:The maximum axial pulout strength and maximum rotation torque of the bone cement and the nano bone putty groups were greater than those of the control group (P < 0.05), and the maximum axial pulout strength and the maximum rotation torque of the bone cement group were greater than those of the nano bone putty group (P < 0.05). These results demonstrate that the maximum axial pulout strength and the maximum rotation torque of pedicle screw implantation in the fixation of osteoporotic vertebral body can be effectively improved by injection of bone cement and nano bone putty, and the strengthening effect of bone cement is more obvious.
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Objective To analyze the possible reasons of failed surgical treatment of acetabular fractures. Methods Various methods were used for positive patient identification, including according to Matta's X-ray assessment and Merle d'Aubigne & Postel hip function score of clinical standards for classification of acetabular fracture reduction surgery were not satisfied or not carried out a reduction and fixation,the clinical evaluation of hip joint as a "bad", occurrence of femoral head subluxation or dislocation, femoral head necrosis and other serious complications. From February 2000 to February 2008, 22 patients including 14 males and 8 females with an average age of 38.6 years (range, 18-72 years) were considered as failed cases. Results 45.5% of these cases were posterior wall fractures which were not given any fixation, 27.3% of them were posterior column fractures which were not fixed, 13.6% of them whose reduction and fixation of anterior wall fractures were not satisfied, and 9.1% of them were anterior column fractures which needed fixation. One case should take open reduction and iternal fixation instead of THA. The rate of misdiagnosis and mistaken diagnosis were 90% if only X-ray evaluation was made and this rate decreased to 8.3% if computed tomography was taken. The rate of wrong selection of operative approach was 100% in 10 cases of misdiagnosis, and which was 58.3% in 12 cases of correct diagnosis. In the 5 patients with correct diagnosis and selection of operative approach, the reasons of failed surgical treatment were due to imperfect surgical skills in 3 cases, and inappropriate fixation patterns in 2 cases. Conclusion The causes of the failure of surgical treatment for acetabular fracture might include preoperative missed diagnosis and misdiagnose, inappropriate approach, and an unreasonable internal fixation with unskillful technique.
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[Objective] To evaluate the biocompatibility in vivo of Mg alloy AZ91D(AZ0),Mg-Mn-Ce(RE0)and their step anodizational materials(AZ1,AZ2,AZ3,RE1,RE2,RE3)by the experiments of intradermal stimulus and sensitivity response.[Methods]According toGB/T 16886.10-1997 Biological Evaluation of Medical Apparatus and Instrument,compared with normal sodium,pure magnesium and medical Ti-6Al-7Nb,the leaching liquor were injected into cutis to evaluate stimulus response,to evaluate sensitivity response by injection and illinition.[Results]RE2 could not prepare leaching liquor,it's kicked out.Intradermal stimulus response:normal sodium,Ti-6A1-7Nb,AZ1,AZ3 groups inflammation responded as degree I,scored 0.The others inflammation responded as degree Ⅱ,scored 1.Sensitivity response:formaldehyde group inflammation responded as degree IV,erythema and edema were degree IV.Normal sodium group inflammation responded as degree I,erythema and edema were degree 0.Ti-6Al-7Nb,AZ1,AZ3 groups inflammation responded as degree Ⅱ,erythema and edema were degree 1.The others inflammation responses were degree Ⅲ,erythema and edema were degree Ⅱ.[Conclusion]The new kinds of magnesium alloy AZ1,AZ3 possesses good preliminary biocompatibility in vivo,so it is very possible to be a new type of bone surgery implant material.