- Neurological Surgery, The Albert Einstein College of Medicine, Bronx, NY 10451, and Winthrop University Hospital, Mineola, NY 11501, USA
Nancy E. Epstein
Neurological Surgery, The Albert Einstein College of Medicine, Bronx, NY 10451, and Winthrop University Hospital, Mineola, NY 11501, USA
DOI:10.4103/2152-7806.76458Copyright: © 2011 Epstein NE This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
How to cite this article: Epstein NE. Efficacy of posterior cervical fusions utilizing an artificial bone graft expander, beta tricalcium phosphate. Surg Neurol Int 31-Jan-2011;2:15
How to cite this URL: Epstein NE. Efficacy of posterior cervical fusions utilizing an artificial bone graft expander, beta tricalcium phosphate. Surg Neurol Int 31-Jan-2011;2:15. Available from: http://sni.wpengine.com/surgicalint_articles/efficacy-of-posterior-cervical-fusions-utilizing-an-artificial-bone-graft-expander-beta-tricalcium-phosphate/
Background:Several cervical laminectomies and instrumented posterior cervical fusions utilize iliac autograft supplemented with demineralized bone matrix, or bone morphogenetic protein, but few utilize artificial bone graft expanders. Here we analyzed whether posterior cervical fusions could effectively utilize iliac autograft supplemented with an artificial bone graft expander, Beta Tricalcium Phosphate [B-TCP]
Materials and Methods:Fifty-three severely myelopathic patients [average Nurick Score 4.1], averaging 65.3 years of age, underwent posterior cervical laminectomies [average 2.3 levels] and multilevel instrumented fusions [average 7.5 levels] utilizing iliac crest autograft and B-TCP. Pathology addressed included multilevel spondylosis accompanied by ossification of the posterior longitudinal ligament [24 patients], ossification of the yellow ligament [27 patients], and instability [53 patients]. Fusion rates [dynamic X-ray, two-dimensional computerized axial tomography (2D-CT) and outcomes [Nurick Grades, Odom's Criteria, SF-36] were assessed at 3, 6, and 12 months postoperatively.
Results:Fusion was confirmed by two independent neuroradiologists utilizing dynamic X-ray studies [100% of patients] and 2D-CT studies [86.8% of patients] an average of 5.4 months postoperatively. Although there were no symptomatic pseudarthroses, three smokers exhibited delayed fusions [8 postoperative months]. Within 1 postoperative year, patients improved an average of 2.7 Nurick Grades [Nurick Score 1.4], Odom's criteria revealed 48 good/excellent, and 5 fair/poor outcomes, and improvement on all 8 SF-36 Health Scales [maximal on Bodily Pain [+21.96].
Conclusions:High fusion rates and improved neurological outcomes were achieved within one year for 53 patients undergoing multilevel level cervical laminectomies with posterior instrumented fusions utilizing iliac autograft supplemented with B-TCP.
Keywords: Artificial Bone Graft Expander, Beta TriCalcium Phosphate, Cervical Laminectomy, Iliac Autograft, Multilevel Instrumented Fusion
Select patients with cervical myelopathy attributed to spinal stenosis and other pathology, with adequate preservation of the cervical lordotic curvature, may be successfully managed with cervical laminectomies and multilevel posterior instrumented fusions. The majority of lateral fusion masses have consisted of lamina and/or iliac crest autograft supplemented with allograft bone graft expanders [e.g., demineralized bone matrix [DBM] or bone morphogenetic protein derivatives [BMP]. However, DBM may adversely transmit viral infections [e.g., HIV, Hepatitis, etc.] or promote allergic/immunologic reactions, while BMP may contribute to cervical cord swelling. This prompted a search for an artificial bone graft expander that could safely be utilized in the cervical spine without complications. Such an artificial bone graft expander, Beta Tricalcium phosphate [B-TCP; Vitoss, OrthoVita, Malvern, PA, USA] was utilized to supplement iliac crest autograft in this series of 53 patients undergoing multilevel cervical laminectomies and posterior cervical fusions. Over the course of the first postoperative year, fusion rates were assessed utilizing both dynamic X-rays and 2D-CT studies, while outcomes were evaluated based upon Odom's Criteria, Nurick Grades, and SF-36 questionnaires.
Clinical Data: In this series, 53 patients averaged 65.3 years of age [range 4782]; 37 patients [70%] were over 60 years of age [
A midline sagittal CT documents multilevel ventral and dorsal/lateral cord compromise/stenosis at the C3-C7 levels. Compression was attributed to both ventral spondylosis/OPLL and dorsolateral OYL. Following laminectomies [C4, C5, C6, and undercutting of C7] with posterior rod/eyelet fusion [C2-T2], the patient's preoperative myelopathy resolved [Grade IV to Grade I].
A T2 sagittal MR study [same patient in
A postoperative T2-weighted MR study [same patient as
Operative Data: Patients underwent 1-3 level laminectomies [average 2.3] and multilevel posterior fusions [average 7.5] [
This photograph demonstrates the application of the eyelets on the rods prior to positioning and placement. Utilizing the rod bender, two similarly configured, mirror-image rods have eyelets applied opposite the retained spinous processes. The rods are then applied dorsally, with the eyelets affixed ventrally. This is followed by passage of a braided titanium cable through the base of the spinous processes; each side of the wire is then brought up through the eyelets and then tightened in a cerclage fashion over the dorsal/superficial rods.
Outcomes Assessment: Odom's Criteria, Nurick Grades, and SF-36 questionnaire data were evaluated preoperatively, and at 6 weeks, 3 months, 6 months, and 12 months postoperatively. To simplify the presentation of SF-36 data, they are presented in 3 groups; mild improvement [05 points], moderate improvement [>5 to 10 points], and marked improvement [>10 points].
X-ray and 2D-CT Fusion Criteria: Confirmation of fusion utilizing both dynamic X-rays and 2D-CT evaluations was independently performed by two neuroradiologists blinded to the study design [Figures
Fusion Rates: At an average of 5.4 months postoperatively, the dynamic X-ray fusion rate was 100%, while the 2D-CT documented fusion rate was 86.8% [
Outcomes: Outcomes were assessed at 1 postoperative year utilizing three different scoring techniques [Tables
Complications: Postoperative morbidity was limited, and there were no mortalities among the 53 patients undergoing cervical laminectomies and multilevel-instrumented fusions utilizing iliac crest autograft, and the artificial bone graft expander, B-TCP. One patient, a smoker and ethanol abuser in his mid-fifties, developed transient bilateral C5 nerve root palsies; the right occurred on postoperative day 3, the left on postoperative day 6. Both deficits fully resolved within 3 postoperative months. Two other patients developed postoperative wound infections. One infection was superficial, while the other was deep [Staphylococcus aureus; Methicillin sensitive] requiring 6 weeks of intravenous antibiotic therapy. Additionally, 4 patients developed wound breakdowns [two at 3 weeks (on Aspirin/Plavix), one at 1 year (on Warfarin), one at 2 years (on Warfarin)]. However, all were attributed to antiplatelet aggregants/anticoagulants as none exhibited wound infections [all cultures negative].
Fusion Techniques: Although cervical laminectomies alone may provide short-term improvement for cervical spondylotic myelopathy (CSM), they are associated with a 15%-37.5% incidence of postoperative instability/kyphosis, and accompanying delayed deterioration.[
Fusion Rates: Other series employing lateral mass screw/rod fixation and allograft/DBM attained similar fusion rates varying from 8998.6% [typically utilizing dynamic X-ray criteria alone] for “open procedures, with some minimally invasive techniques reporting 100% fusion rates utilizing varying fusion criteria”.[
High rates of fusion [X-ray 100%, 2D-CT 86.6%] were achieved following cervical laminectomies accompanied by multilevel posterior rod/eyelet/cable fusions utilizing lamina autograft and an artificial bone graft expander, B-TCP. Fusion rates proved comparable to those achieved with allograft/DBM, while avoiding the inherent risks of other allografts.
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