- 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:10.4103/2152-7806.76146Copyright: © 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 and outcomes of dynamic-plated single-level anterior diskectomy/fusion with additional analysis of comparative costs. Surg Neurol Int 24-Jan-2011;2:9
How to cite this URL: Epstein NE. Efficacy and outcomes of dynamic-plated single-level anterior diskectomy/fusion with additional analysis of comparative costs. Surg Neurol Int 24-Jan-2011;2:9. Available from: http://sni.wpengine.com/surgicalint_articles/efficacy-and-outcomes-of-dynamic-plated-single-level-anterior-diskectomyfusion-with-additional-analysis-of-comparative-costs/
Background:Few studies focus on the fusion rates and outcomes for single-level anterior cervical diskectomy/fusion (1-ACDF) utilizing iliac autograft and dynamic plates.
Methods:Fusion rates and outcomes were prospectively evaluated in 60 consecutive patients undergoing 1-ACDF utilizing iliac autograft and dynamic plates (ABC; Aesculap, Tuttlingen, Germany). Eighteen patients had radiculopathy, while 42 were myelopathic (average Nurick Score 3.3). Pathology included single-level disc disease/spondylosis (38 patients) and/or ossification of the posterior longitudinal ligament (OPLL, 22 patients). Fusion was assessed at 3, 6, and up to 12 months postoperatively utilizing dynamic X-rays and 2D-CT scans. Outcomes were evaluated up to 24 months postoperatively utilizing Odom's Criteria, Nurick Grades, and Short-Form 36 (SF-36) outcome questionnaires. Patients were followed for an average of 4.8 postoperative years (minimum 2 years).
Results:Although dynamic X-rays/2D-CT studies documented 100% fusion an average of 3.8 months (range 2.5-8 months] postoperatively, 5 heavy smokers exhibited delayed fusions [6-8 months postoperatively]. Two years postoperatively, the average Nurick Score was 0.3 (mild radiculopathy), while Odom's Criteria revealed 52 excellent, 6 good, and 2 fair outcomes [the latter 8 patients were heavy smokers]). Utilizing SF-36 outcome questionnaires, patients markedly improved (>10.0 point gain) on 5 of 8 Health Scales within 6 months, 7 of 8 within 1 year, and all 8 within 2 postoperative years.
Conclusions:For 60 patients undergoing 1-ACDF utilizing dynamic plates, ultimately a 100% fusion rate was achieved (5 heavy smokers exhibited delayed fusions). Two years postoperatively, Nurick Grades, Odom's Criteria, and SF-36 questionnaires revealed adequate outcomes.
Keywords: Single-level, Anterior Cervical Diskectomy/Fusion, SF-36 Outcomes, Fusion Rates, Autograft, Dynamic Plates
Few studies document the efficacy of utilizing iliac crest autograft with dynamic plates (ABC; Aesculap, Tuttlingen, Germany) for performing single-level anterior cervical diskectomy and fusion (1-ACDF) addressing disc disease/spondylosis or ossification of the posterior longitudinal ligament (OPLL). One-year fusion rates (dynamic X-rays and 2D-CT studies) and 2-year outcomes (Nurick Grades, Odom's Criteria, and Short-Form (SF-36) questionnaires) were assessed for 60 such patients undergoing single-level anterior cervical diskectomy and fusion (1-ACDF) utilizing iliac crest autograft and dynamic plates.
Sixty patients, 33 females and 27 males, underwent 1-ACDF utilizing iliac crest autograft and dynamic ABC plates [
MR and CT Studies
Preoperatively, both MR and CT studies were obtained to document cervical disc disease/spondylosis (38 patients) or OPLL (22 patients) [Figures
On this noncontrast axial CT study, at the level of the interspace, a central ossified intradural mass is seen which is separated from the posterior margin of the vertebral body by the interposed hypodense dura. This is the classical image of the “double-layer sign” for OPLL that is highly associated with cerebrospinal fluid fistulas during anterior cervical surgery. This patient developed an intraoperative CSF fistula which was effectively treated with a sewn-in [7-0 Gortex Sutures] dural graft, fibrin sealant, and microfibrillar collagen
Documentation of Fusion
Postoperative fusion rates, assessed by two independent neuroradiologists blinded to the study design, were based upon both dynamic X-ray and 2D-CT studies obtained at 3, 4.5, 6, and up to 12 months postoperatively and/or until fusion occurred [Figures
This lateral cervical plain X-ray demonstrates adequate dynamic plate and graft localization. The interbody graft appears incorporated, as there is bony trabeculation and no lucency at the graft/vertebral body interface. Note the 3-4 mm superior and inferior migration of the plate over the vertebral body screw heads
The sagittal midline 2D-CT study obtained 6 months postoperatively following iliac autograft and dynamic ABC plate placement documented an adequate fusion. Observe the lack of lucency and the presence of bony trabeculation at the graft/vertebral body interfaces superiorly and inferiorly. A further fusion criterion is the lack of lucency surrounding the vertebral screws. Also note the 3-4 mm of cephalad and caudad screw migration within the plate minimizing stress shielding and allowing for graft settling/fusion.
Outcomes were analyzed utilizing Nurick Grades, Odom's Criteria, and the SF-36 questionnaires. Nurick Grades and SF-36 questionnaires were assessed preoperatively, and at 3, 6, 12, and 24 months postoperatively, while Odom's Criteria were evaluated over these same intervals but only postoperatively. To simplify the presentation of SF-36 results, data were divided into three categories of “improvement.” At each time interval, data were compared with preoperative baselines, e.g., minimal improvement (± 0−5 points), moderate improvement (± 6−10 points), and marked improvement (>10 points).
Outcomes were assessed utilizing Nurick Grades/Scores, Odom's Criteria, and SF-36 questionnaires up to 2 years postoperatively. By the second postoperative year, patients improved an average of 3.0 Nurick Grades; the average preoperative Nurick Score was 3.3 (moderate myelopathy), while the mean postoperative Nurick Score was 0.3 (mild radiculopathy) [
Of interest, patients demonstrated the greatest postoperative improvement on the BP health scale by the sixth postoperative week; BP increased from the preoperative baseline of 25.9 to 52.5. Although further increases were observed between 3 months and 2 years postoperatively (56.6 at 3 months, 58.0 at 6 months, 70.5 at 1 year, and 76.7 at 2 years), the largest gains occurred early on (6 weeks;
Utilizing both dynamic X-rays and 2D-CT studies, the average time to fusion was 3.8 months (range 2.5-8 months) [
There were two major and three minor complications in this series. Major complications included one vertebral artery injury (successfully embolized without sequelae) and one cerebrospinal fluid fistula (adequately treated with duragen/fibrin sealant without shunting); both occurred in patients with OPLL. Three minor complications occurred: [
High fusion rates have been observed for 1-ACDF utilizing different grafts and/or fixed and dynamic plates. In Fraser et al.'s meta-analylsis of the literature, which included 21 papers [involving at least 25 cases/study with a minimum 1-year follow-up], the overall fusion rate was 89.5% (2682 patients).[
Typically, comparable outcomes have been reported utilizing varied grafts and/or plating systems for performing 1-ACDF. Good/excellent outcomes were observed in 91.3% of patients undergoing 1-ACDF with (31 patients) or without (38 patients) fixed/semiconstrained plates.[
Although 1-ACDF is one of the most frequently performed cervical operations in the USA, few studies focus on the cost-effectiveness of different types of plates, spacers (autograft, allograft, wire mesh, and PEEK), and bone graft supplements (bone morphogenic protein [BMP], DBM, and beta tricalcium phosphate [B-TCP]). One series determined comparable costs for three different types of 1-ACDF spacers/constructs ((1) plate/cage/bone substitute, (2) cage alone, and (3) disc arthroplasty); the fourth plate/iliac autograft construct, although utilizing less costly instrumentation, proved to be less cost-effective due to a longer length of stay (LOS; 5 days).[
In a separate study, Epstein et al. analyzed instrume-ntation charges (charges to the insurer by the hospital; not the actual original costs of these items) for performing 102 single-level ACDF performed by 15 different surgeons at a single institution in 2008.[
As society focuses on the rising costs of medical care, we as spine surgeons should more actively participate in correlating costs of the different instrumentation systems/constructs with fusion rates and outcomes. The aim of this study was to reaffirm the value of iliac crest autograft and dynamic plates in performing 1-ACDF, a construct which produced more than adequate outcomes and fusion rates but at a lesser cost. Although major economic interests may promote other more expensive plates (constrained [fixed] or semiconstrained) and spacers, the focus should remain on quality of outcomes, fusion rates, and cost containment.
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