Biomechanical study of anterior transpedicular screw fixation for subaxial cervical three-column injury / 中华创伤骨科杂志

Objective To compare the initial stability between anterior transpedicular screw (ATPS) fixation,anterior plate (AP) fixation and combining anterior and posterior (CAP) fixation for subaxial cervical three-column injury.Methods Six specimens of cervical spine were prepared.After measurement of the range of motion (ROM) of the intact cervical spine,the specimens were made into models of three-column injury.After the models were simulatively reconstructed using an anterior cervical cage,they were stabilized by ATPS,AP and CAP.After the ROMs of the models in the 3 fixation states were measured,the data were normalized by standardizing them to the intact state ROM which was set at 100％.The normalized ROMs of the models in the 3 fixation states were compared.Results The normalized ROMs of AP fixation state in flexion,extension,lefi lateral bending,right lateral bending,left axial rotation and right axial rotation were 119.68±8.34％,119.63±6.74％,115.20±7.91％,117.47±7.81％,120.67±5.99％ and 112.35 ± 8.42％,respectively,significantly larger than those of the intact state (P ＜ 0.05).The normalized ROMs of the other 2 states in all directions were significantly smaller than those of the intact state (P ＜0.05).The normalized ROM of ATPS state in flexion was 87.48 ± 5.31％,significantly larger than that of CAP state (69.60 ± 2.06％) (P ＜ 0.05).There were no significant differences between the normalized ROMs of ATPS state and those of CAP state in extension (65.53 ± 4.36％ versus 67.17 ± 3.10％),in left lateral bending (82.13 ± 2.85％ versus 82.30 ±4.69％),in right lateral bending (81.78 ± 3.42％ versus 81.27 ± 2.79％),in left axial rotation (83.20 ± 2.30％ versus 82.95 ± 2.40％),or in right axial rotation (83.03 ± 1.30％ versus 83.60 ± 6.56％) (P ＞ 0.05).Conclusions In subaxial cervical three-column injury,the initial stability of ATPS fixation may be superior to that of AP fixation and similar to that of CAP fixation.We believe that ATPS can provide enough initial stability for subaxial cervical three-column injury.

The surgical treatment of the chronic atlantoaxial rotatory dislocation with C1, 2 lateral facet locked through combined anterior and posterior approach / 中华骨科杂志

Objective To describe the clinical manifestation of the chronic atlantoaxial rotatory dislocation (AARD) with C1,2 lateral facets locked,and explore the effect of the operation combined with anterior retropharyngeal approach and posterior approach.Methods Data of 8 patients with chronic AARD with C1,2 lateral facet locked who had undergone open reduction with the anterior retropharyngeal approach and C 1,2 transpedicular screw fixation with autologous iliac bone graft from Oct.2010 to Jun.2013 were retrospectively analyzed.There were 4 males and 4 females with an average age of 31 years old (range,11-57 years old).The intervals from onset to diagnosis were from 29 to 180 days and the mean time was 70.6 days.5 cases were chronic AARD with right C1,2 lateral facets locked and 3 with left C1,2 lateral facets locked.Reduction was failed to obtain by traction for two to four weeks.Subsequently,after open reduction with the anterior retropharyngeal approach,the patients were performed C 1,2 transpedicular screw fixation with autologous iliac bone graft for one stage or two.Results 1 patient underwent open reduction with the anterior retropharyngeal approach in stage one and C1,2 transpedicular screw fixation in stage two because of an overall severe condition,and the other patients did anterior and posterior operation in one stage.The average operation time was 205 min (range,160-260 min).The mean blood loss was 210 ml (range,100-300 ml).There were no operation complications except one young girl reflected pain in autologous iliac donated area,and pain relieved when taking non-steroidal anti-inflammatory by oral for one week.All patients had been followed up for a mean period of 14.8 months (range,5-37 months).Three-dimensional computed tomography revealed C1,2 arthrodesis bone graft fusion from two to four months and the average was 3.1 months.Neither recurrence of symptoms nor dislocation was observed at the latest follow-up.Conclusion Open reduction through the anterior retropharyngeal approach with C1,2 transpedicular screw fixation is an effective treatment strategy for chronical AARD with C1,2 lateral facets locked,which reduces surgical complications with less operation difficulty.

Biomechanical evaluation of immediate stability of biodegradable multi-amino acid copolymer/tri-calcium phosphate composite interbody Cages in a goat cervical spine model / 生物医学工程学杂志

<p><b>UNLABELLED</b>A new kind of Interbody Cage made of multi-amino acid copolymer/tri-calcium phosphate (MAACP/TCP) composite was designed, and the purpose of this study was to evaluate immediate stability of MAACP/TCP Cage in a goat cervical spine model (C3-4). After the motion segment C3-4 was tested intact, 27 goat cervical spines were divided into three groups randomly. There were four groups group A. MAACP/TCP Cage group (n = 9), group B2 titanium Cage group (n = 9), group C2 autologous tricortical iliac crest bone group (n = 9) and group D: intact group (n = 27). Different Cage groups were implanted after complete discectomy (C3-4) was performed. Then they were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method. The range of motion (ROM) and relative stiffness were calculated and compared between groups. In comparison to the intact motion segment, MAACP/TCP Cage showed a significantly (P < 0.05) lower ROM and a significantly (P < 0.05) higher relative stiffness in flexion and lateral bending. In comparison to the tricortical iliac crest bone graft, MAACP/TCP Cage showed a significantly (P < 0.05) lower ROM and a significantly (P < 0.05) higher relative stiffness in extension, flexion and lateral bending. There was no significant (P > 0.05) difference in the ROM and relative stiffness between MAACP/TCP Cage and titanium Cage in extension, flexion and lateral bending. In comparison to titanium Cage, MAACP/TCP Cage showed a significantly (P < 0.05) higher ROM and a significantly (P < 0.05) lower relative stiffness in rotation.</p><p><b>CONCLUSION</b>MAACP/TCP Cage can provide enough immediate stability for cervical interbody fusion in a goat cervical spine model.</p>

Study of the immediate biomechanical stability in a goat cervical spine model / 生物医学工程学杂志

A new kind of Cage made of poly-DL-lactic acid was designed and an in-vitro study was conducted to evaluate the biomechanical effect of PDLLA Cage on a goat cervical spine model. 27 goat cervical spines were divided into four groups randomly: intact group, PDLLA Cage group, titanium Cage group, and autologous tricortical iliac crest bone group. Different implants were implanted after complete discectomy (C3-4) was performed, then they were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method using a nonconstrained testing apparatus, and three-dimensional displacement was measured. The range of motion (ROM) and the mean stiffness values were calculated and compared between groups. The result showed that the ROM values between PDLLA Cage group and the titanium Cage group were not significantly different in extensional and rotational movement (P > 0.05), but they were lower than that of rest groups (P < 0.05). In flexional loading mode, the ROM values showed statistically significant difference between the four groups (P < 0.05). And in lateral bending loading mode, no significant difference was found between PDLLA Cage group and iliac crest bone group (P > 0.05), but significant difference was found among the other groups (P < 0.05). The stiffness of cervical spine was raised after Cage was implanted. In flexional and rotational loading mode, significant difference in stiffness was found between PDLLA Cage group and control group or iliac crest bone group (P < 0.05). So PDLLA Cage can provide enough primary stability for cervical intervertebral fusion.