Biomechanical study of the stability of subaxial cervical anterior transpedicular screw fixation for three-column injury / 中国骨伤

<p><b>OBJECTIVE</b>To compare the stability of subaxial cervical anterior transpedicular screw(ATPS) fixation and three traditional fixations for three-column injury.</p><p><b>METHODS</b>Six specimens of cervical spine were prepared. After measurememt of the range of motion(ROM) in intact state, the specimens were made into three-column injury models. The models were reconstructed with an anterior cervical cage, and stabilized by ATPS, anterior plate(AP), anterior plate + lateral mass screw(AP+LMS) and posterior transpedicular screw(PTPS). The ROM of the models in the four states were measured, and the results of data were compared after standardization.</p><p><b>RESULTS</b>The normalized ROM of ATPS state in flexion-extension, lateral bending, axial rotation were(77.17±4.75)%, (82.00±2.61)%, (83.17±2.23)%, which were significant small than those in intact state(<0.05). The normalized ROM of AP state in flexion-extension, lateral bending, axial rotation were(119.67±7.42)%, (116.33±7.53)%, (112.67±5.99)% , which were significant larger than those in intact state(<0.05). The normalized ROM of AP in all directions were significant larger than those of ATPS(<0.05). There was no significant difference between normalized ROM of PTPS state and those of ATPS state in flexion-extension and lateral bending(>0.05). The normalized ROM of PTPS state in axial rotation was(6.83±2.48)% and was significant larger than that of ATPS state(=0.009). The normalized ROM of AP+LMS state in flexion-extension was(68.50±2.43)%, which was significant smaller than that of ATPS state(=0.003). There was no significant difference between the normalized ROM of AP+LMS state and those of ATPS state in lateral bending and axial rotation(>0.05).</p><p><b>CONCLUSIONS</b>Subaxial cervical three-column injury model reconstruction by ATPS can provide the adequate primary stability, of which biomechanics property is superior compared to AP and PTPS, and is similar to that of AP+LMS. It can be applied to the patients with no need to decompression and reduction through posterior approach.</p>

Evidence-based guideline for the management of acute subaxial cervical spine injury / 中华外科杂志

In order to provide the clinical guidelines of acute subaxial cervical spine injury for the Chinese orthopedic surgeons, the Spine Trauma Group of Chinese Association of Orthopedic Surgeons compiled this guidelines.The guidelines apply to adult patients with acute (less than 3 weeks) subaxial cervical spine and/(or) spinal cord or nerve root injuries. The Study Group wrote the guidelines by setting up questions, determining search words, screening literatures according to inclusion and exclusion criteria, analyzing the included literatures, confirming evidence levels and then providing recommendations. The guidelines include 141 literatures, 27 Chinese articles and 114 English articles. The guidelines set up 18 questions divided into 4 sections: pre-hospital care, diagnosis and evaluation, treatment and prevention of complications, which include 39 recommendations.

Evidence-based guideline for the management of acute subaxial cervical spine injury / 中华外科杂志

In order to provide the clinical guidelines of acute subaxial cervical spine injury for the Chinese orthopedic surgeons, the Spine Trauma Group of Chinese Association of Orthopedic Surgeons compiled this guidelines.The guidelines apply to adult patients with acute (less than 3 weeks) subaxial cervical spine and/(or) spinal cord or nerve root injuries. The Study Group wrote the guidelines by setting up questions, determining search words, screening literatures according to inclusion and exclusion criteria, analyzing the included literatures, confirming evidence levels and then providing recommendations. The guidelines include 141 literatures, 27 Chinese articles and 114 English articles. The guidelines set up 18 questions divided into 4 sections: pre-hospital care, diagnosis and evaluation, treatment and prevention of complications, which include 39 recommendations.

Polyetheretherketone Cage with Demineralized Bone Matrix Can Replace Iliac Crest Autografts for Anterior Cervical Discectomy and Fusion in Subaxial Cervical Spine Injuries

OBJECTIVE: This study aimed to compare the clinical and radiologic outcomes of patients with subaxial cervical injury who underwent anterior cervical discectomy and fusion (ACDF) with autologous iliac bone graft or polyetheretherketone (PEEK) cages using demineralized bone matrix (DBM). METHODS: From January 2005 to December 2010, 70 patients who underwent one-level ACDF with plate fixation for post-traumatic subaxial cervical spinal injury in a single institution were retrospectively investigated. Autologous iliac crest grafts were used in 33 patients (Group I), whereas 37 patients underwent ACDF using a PEEK cage filled with DBM (Group II). Plain radiographs were used to assess bone fusion, interbody height (IBH), segmental angle (SA), overall cervical sagittal alignment (CSA, C2–7 angle), and development of adjacent segmental degeneration (ASD). Clinical outcome was assessed using a visual analog scale (VAS) for pain and Frankel grade. RESULTS: The mean follow-up duration for patients in Group I and Group II was 28.9 and 25.4 months, respectively. All patients from both groups achieved solid fusion during the follow-up period. The IBH and SA of the fused segment and CSA in Group II were better maintained during the follow-up period. Nine patients in Group I and two patients in Group II developed radiologic ASD. There were no statistically significant differences in the VAS score and Frankel grade between the groups. CONCLUSION: This study showed that PEEK cage filled with DBM, and plate fixation is at least as safe and effective as ACDF using autograft, with good maintenance of cervical alignment. With advantages such as no donor site morbidity and no graft-related complications, PEEK cage filled with DBM, and plate fixation provide a promising surgical option for treating traumatic subaxial cervical spine injuries.

A Novel Patient-Specific Drill Guide Template for Pedicle Screw Insertion into the Subaxial Cervical Spine Utilizing Stereolithographic Modelling: An In Vitro Study

STUDY DESIGN: Cadaveric study. PURPOSE: The purpose of this study was to assess the accuracy and feasibility of cervical pedicle screw (CPS) insertion into the subaxial cervical spine placed using a patient-specific drill guide template constructed from a stereolithographic model. OVERVIEW OF LITERATURE: CPS fixation is an invaluable tool for posterior cervical fixation because of its biomechanical advantages. The major drawback is its narrow corridor that allows very little clearance for neural and vascular injuries. METHODS: Fifty subaxial pedicles of the cervical vertebrae from five cadavers were scanned into thin slices using computed tomography (CT). Digital imaging and communications in medicine images of the cadaver spine were digitally processed and printed to scale as a three-dimensional (3D) model. Drill guide templates were manually moulded over the 3D-printed models incorporating pins inserted in the pedicles. The drill guide templates were used for precise placement of the drill holes in the pedicles of cadaveric specimens for pedicle screw fixation. RESULTS: The instrumented cadaveric spines were subjected to CT to assess the accuracy of our pedicle placement by an external observer. Our patient-specific drill guide template had an accuracy of 94%. CONCLUSIONS: The use of a patient-specific drill guide constructed using stereolithography improved the accuracy of CPS placement in a cadaveric model.

The Secondary Contiguous or Non-contiguous Subchondral Bone Impactions in Subaxial Cervical Spinal Injury: Incidence and Associated Primary Injury Patterns

PURPOSE: To evaluate the incidence of secondary contiguous or non-contiguous subchondral bone impactions (SBI) in subaxial cervical spinal injury and associated primary injury patterns. MATERIALS AND METHODS: A retrospective review of computed tomography, magnetic resonance imaging, and medical records was carried out for 47 patients who had sustained a subaxial cervical spinal injury. Presence, number, level, and sites of secondary contiguous or non-contiguous SBI were recorded. To evaluate primary injury patterns, the level and number of primary injury sites of subaxial cervical spine injury, injury morphology, anterior/posterior discoligamentous complex (ADC/PDC) injury, posterior ligamentous complex (PLC) injury, spinal cord injury, and mechanism of injury (MOI) were analyzed. Differences in primary injury pattern of subaxial cervical spine injury and MOI between patients with and without SBI, and between contiguous or non-contiguous SBI were analyzed using the Mann-Whitney U test, Pearson's chi square test and Fisher's exact test. RESULTS: Eighteen patients (18/47, 38.29%) had developed contiguous (n=9) or non-contiguous (n=9) SBI, most commonly involving T3 (15/47, 31.91%) and 3 levels (6/18, 33.33%). All SBIs had developed near the anterosuperior region of the body and the superior endplate and were the result of a high-impact MOI. SBIs were statistically significant in association with injury morphology and PLC injury (P=0.001, P=0.009, respectively) at the primary injury site. Non-contiguous SBI was more frequently accompanied by upper cervical spinal injuries in association with PDC injuries, as opposed to contiguous SBI, with statistical significance (P=0.009), while no other statistically significant differences were found. CONCLUSION: Secondary SBIs are common and probably associated with subaxial cervical spinal injuries with high energy compressive flexion forces.

Radiographic Analysis of Atlantoaxial Fusion for Atlantoaxial Instability: Comparison of Posterior wiring, Transarticular screw, Posterior screw-rod fixation

STUDY DESIGN: This is a retrospective study. OBJECTIVES: We wanted to clarify the association between the position of the atlantoaxial fusion angle and the change of the subaxial cervical spine alignment (SCA) and the reduction loss after atlantoaxial fusion (AAF) using the posterior wiring technique (PWT), transarticular screw fixation (TAF) and posterior screw-rod fixation (PSR) for treating atlantoaxial instability (AAI). SUMMARY OF LITERATURE REVIEW: There are not many studies on the change of the SCA and the reduction loss after AAF. MATERIALS AND METHODS: Thirty five patients underwent AAF for AAI from 1986 to 2008. The mean follow-up period was 59.5 months. The surgical techniques were divided into three groups, that is, PWT: 17 patients, TAS: 10 and PSR: 8. The causes of instability were transverse ligament rupture in 12 patients, rheumatoid arthritis in 11, Os odontoideum in 6 and nonunion of an odontoid fracture in 6. Plain radiographs were used to assess the atlanto-dental interval, the posterior arch-lamina angle, the change of the SCA and the time of fusion. RESULTS: Fusion was achieved in all the patients within 3.5 months (range: 3-5 months). The radiologic findings in the 5 PWT patients showed a reduction loss and 3 patients showed subaxial cervical kyphosis (SCK). The TAS group had no reduction loss or SCK. The PSR group had no reduction loss and one patient showed SCK. A statistically significant reduction loss and SCK occurred in the group in which there was a posterior arch-laminar angle greater than 10 degrees before and after surgery. CONCLUSIONS: For the treatment of AAI, the position of the AAF is associated with the change of the postoperative SCA. The preoperative lodortic position of C1-2 should be maintained to prevent the change of the SCA.

Transarticular screws versus Magerl lateral mass screws:an anatomic comparison of their possible effects on injury to spinal nerve roots / 中华创伤骨科杂志

Objective To compare anatomically the potential incidences of injury to the nerve roots of ventral and dorsal rami caused by the transarticular screws and Magerl lateral mass screws in the fixation of subaxial cervical spine.Methods Fixations with the transarticular screws and Magerl lateral mass screws were performed in this study.For each kind of fixation,20 screws were inserted from C3 to C7 in two specimens.A 20-ram long screw was used to over-penetrate the ventral cortex.The anterolateral aspect of the cervical spine was carefully dissected to allow ob- servation of the screw-ramus relationship.Results The overall percentage of nerve violation was significantly lower in the transarticular screw fixation(45%)than in the Magerl lateral mass screw fixation(90%).The difference was sta- tistically significant between the two fixation methods(P＜0.05).The greatest percentages of nerve violation caused by the transarticular screws and lateral mass screws were found at the dorsal ramus,25% and 45%,respectively. Conclusion The potential risk of nerve root violation caused by the transarticular screw technique is lower than that by the Magerl lateral mass screw technique in the lower cervical spine.

Analysis of Posterior Cervical Fixation and Fusion in Subaxial Cervical Spine Injury

OBJECTIVE: In the retrospective analyzing 19 consecutive patients with subaxial cervical spine(C3~T1) injury treated by posterior cervical fixation and fusion, clinical manifestation, radiologic finding, operative technique, and postoperative results following 6 months were analyzed. MATERIALS AND METHODS: Most common fracture level was C4-5, mean age 41, and male to female ratio 13: 6. The most common cause of injury was motor vehicle accident(17 cases). In 19 cervical procedures, interspinous triple wiring was done in 14 cases, lateral mass plating in 5 cases, and additional anterior fusion in 2 cases. RESULTS: Twelve weeks after operation, all cases were reviewed by plain cervical radiogram. In 17 cases that treated by posterior fusion only, 14 cases(81%) had kyphotic angle change less than 5degrees, 2 cases(12%) 5-20degrees, and 1 case(6%) more than 20degrees. Overall fusion rate was 88%, and there was no significant difference of bone fusion rate between autogenous bone graft and allogenous bone graft. CONCLUSION: In the case of severe posterior column injury or displacement, posterior approach seems superior to anterior approach, but in the case of combined anterior column injury, anterior approach is considered necessary. In this study, posterior fixation and fusion might be acceptable procedure for subaxial cervical fracture and dislocation, owing to its high fusion rate, low kyphotic angulation and low operation related complication rate.