Cervical spine locking plate: in vitro biomechanical testing (original) (raw)
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A Biomechanical Comparison of Modern Anterior and Posterior Plate Fixation of the Cervical Spine
Spine, 2001
Study Design. A biomechanical study was designed to assess relative rigidity provided by anterior, posterior, or combined cervical fixation using cadaveric cervical spine models for flexion-distraction injury and burst fracture. Objectives. To compare the construct stability provided by anterior plating with locked fixation screws, posterior plating with lateral mass screws, and combined anterior-posterior fixation in clinically simulated 3-column injury or corpectomy models. Summary of Background Data. Anterior plating with locked fixation screws is the most recent design and is found to provide better stability than the conventional unlocked anterior plating. However, there are few data on the direct comparison of biomechanical stability provided by anterior plating with locked fixation screws versus posterior plating with lateral mass screws. Biomechanical advantages of using combined anterior-posterior fixation compared with that of using either anterior or posterior fixation alone also have not been well investigated yet. Methods. Biomechanical flexibility tests were performed using cervical spines (C2-T1) obtained from 10 fresh human cadavers. In group I (5 specimens), onelevel, 3-column injury was created at C4-C5 by removing the ligamentum flavum and bilateral facet capsules, the posterior longitudinal ligament, and the posterior half of the intervertebral disc. In group II (5 specimens), complete corpectomy of C5 was performed to simulate burst injury. In each specimen, the intact spine underwent flexibility tests, and the following constructs were tested: (1) posterior lateral mass screw fixation (Axis plate) after injury; (2) polymethylmethacrylate anterior fusion block plus posterior fixation; (3) polymethylmethacrylate block plus anterior (Orion plate) and posterior plate fixation; and (4) polymethylmethacrylate block plus anterior fixation. Rotational angles of the C4-C5 (or C4-C6) segment were measured and normalized by the corresponding angles of the intact specimen to study the overall stabilizing effects. Results. Posterior plating with an interbody graft showed effective stabilization of the unstable cervical segments in all loading modes in all cases. There was no significant stability improvement by the use of combined fixation compared with the posterior fixation with interbody grafting, although combined anterior-posterior fixation tended to provide greater stability than both anterior and posterior fixation alone. Anterior fixation alone was found to fail in stabilizing the cervical spine, particularly in the flexion-distraction injury model in which no contribution of posterior ligaments is available. Anterior plating fixation provided much greater fixation in the corpectomy model than in the flexion-distraction injury model. This finding suggests that preservation of the posterior ligaments may be an important factor in anterior plating fixation. Conclusions. This study showed that the posterior plating with interbody grafting is biomechanically superior to anterior plating with locked fixation screws for stabilizing the one-level flexion-distraction injury or burst injury. More rigid postoperative external orthoses should be considered if the anterior plating is used alone for the treatment of unstable cervical injuries. It was also found that combined anterior and posterior fixation may not improve the stability significantly as compared with posterior grafting with lateral mass screws and interbody grafting.
European Spine Journal, 2007
Anterior cervical plate fixation is an approved surgical technique for cervical spine stabilization in the presence of anterior cervical instability. Rigid plate design with screws rigidly locked to the plate is widely used and is thought to provide a better fixation for the treated spinal segment than a dynamic design in which the screws may slide when the graft is settling. Recent biomechanical studies showed that dynamic anterior plates provide a better graft loading possibly leading to accelerated spinal fusion with a lower incidence of implant complications. This, however, was investigated in vitro and does not necessarily mean to be the case in vivo, as well. Thus, the two major aspects of this study were to compare the speed of bone fusion and the rate of implant complications using either rigid-or dynamic plates. The study design is prospective, randomized, controlled, and multi-centric, having been approved by respective ethic committees of all participating sites. One hundred and thirty-two patients were included in this study and randomly assigned to one of the two groups, both undergoing routine level-1-or level-2 anterior cervical discectomy with autograft fusion receiving either a dynamic plate with screws being locked in ap-position (ABC, Aesculap, Germany), or a rigid plate (CSLP, Synthes, Switzerland). Segmental mobility and implant complications were compared after 3-and 6 months, respectively. All measurements were performed by an independent radiologist. Mobility results after 6 months were available for 77 patients (43 ABC/34 CSLP). Mean segmental mobility for the ABC group was 1.7 mm at the time of discharge, 1.4 mm after 3 months, and 0.8 mm after 6 months. For the CSLPgroup the measurements were 1.0, 1.8, and 1.7 mm, respectively. The differences of mean segmental mobility were statistically significant between both groups after 6 months (P = 0.02). Four patients of the CSLP-group demonstrated surgical hardware complications, whereas no implant complications were observed within the ABC-group (P = 0.0375). Dynamic plate designs provided a faster fusion of the cervical spine compared with rigid plate designs after prior spinal surgery. Moreover, the rate of implant complications was lower within the group of patients receiving a dynamic plate. These interim results refer to a follow-up period of 6 months after prior spinal surgery. Further investigations will be performed 2 years postoperatively.
Is Anterior-Only Fixation Adequate for Three-Column Injuries of the Cervical Spine?
Asian Spine Journal
To analyze the clinical and functional outcomes of patients who have undergone anterior cervical discectomy/corpectomy and fusion (ACDF/ACCF) for a three-column cervical spine injury (CSI). Overview of Literature: The treatment of choice for a three-column CSI is an area of contention; however, combined anterior and posterior fixation is the preferred method explored in the literature. Studies have shown the superior biomechanical stability of posterior fixation over that of anterior fixation, but anterior-only approach in CSI has been proving its efficacy in recent times by providing reasonable stability with the maximum achievable decompression and fusion. Methods: Twenty-one patients undergoing ACDF/ACCF with a bone graft/metallic cage treatment for cervical injuries involving all three columns from January 2016 to July 2018 were included in the study. All of the patients were followed up monthly for the first 3 months and then every 6 months, until their last follow-up visit. Results: Nineteen patients had AO type C injuries and were managed with ACDF, and two patients with AO type B injuries were managed with ACCF. Fifteen had a complete spinal cord injury, while six had an incomplete spinal cord injury (American Spinal Injury Association B, C, and D). The mean segmental kyphosis at presentation of 12.2°±4.4° improved in the postoperative period to-7.2°±2.5°. At their final follow-up, all the patients showed clinical improvements when assessed by the Visual Analog Scale (6.8-1.8), Oswestry Disability Index score (59.7-34.9), and Spinal Cord Independence Measure score (24.8-36.4). One patient in the ACDF group needed a secondary posterior fixation because of instability. Conclusions: An anterior approach to the cervical spine in cervical fracture dislocations is an effective treatment showing an optimal recovery rate in terms of patient-reported outcomes and structural stability, with the added advantages of less blood loss and the fact that the technique requires less instrumentation.
Posterior plates in the management of cervical instability: long-term results in 44 patients
Journal of Neurosurgery, 1994
✓ Although posterior plates are increasingly used to manage cervical spinal instability, long-term follow-up evaluation of patients with a critical analysis of efficacy and complications has not been reported. The authors have retrospectively analyzed the outcome in 44 consecutive patients (37 males and seven females, age range 16 to 80 years) treated with posterior cervical plates. The indications for instrumentation were instability due to trauma in 42 cases, tumor in one, and infection in one. In four patients the follow-up period was limited to 3, 5, 11, and 16 months. Two patients died of chronic medical problems 4 and 9 months after treatment. The remaining 38 patients were followed from 2 to 6 years (mean 46 months). One motion segment was stabilized in 23 patients using two-hole plates; two motion segments were stabilized in the other 21 patients using three-hole plates. In the majority of patients (37 cases), supplemental bone grafting was not used. Patients were immobilize...
Journal of clinical investigation and studies, 2020
Background: Anterior cervical discectomy and fusion with plate implementation represents one of the most used procedure for the treatment of single-and multilevel cervical degenerative disc disease. Since few information are reported about clinical complication related to the use of plate, the aim of this retrospective study is to evaluate qualitatively and quantitatively the intra-operative and post-operative complications. Methods: Fifty-five (55) patients (23 males and 32 females, mean age 49.8 years/old) who underwent cervical fusion by intervertebral TiPEEK cage, and 3 cervical plate were retrospectively reviewed for clinical and radiological outcomes. Results: Cervical spinal fusion was performed at one level in 24 patients (43.6%), at two levels in 26 patients (47.3%), and at three levels in 5 patients (9.1%). The computed tomography scan of two patients included in this retrospective analysis was not available after one year from surgery (3.6%). The remaining 53 patients (96.4%) had a complete proven fusion. At a mean follow-up of 38.6 months, the clinical outcomes were "excellent", "very good" or "good" for 47.3%, 27.3% and 16.4% of patients respectively. Only 9.1% reported a "poor" outcome. No adverse effects were observed after the use of cervical Mecta-C plates. Conclusions: This retrospective study showed no clinical complication or adverse event after anterior cervical discectomy and fusion with plate implementation demonstrating the safety of Mecta-C cervical plate as an effective support of the TiPEEK cage.