Use of polyetheretherketone spacer and recombinant human bone morphogenetic protein-2 in the cervical spine: a radiographic analysis
ABSTRACT Results recently reported in the literature have raised some concerns regarding the use of recombinant human bone morphogenetic protein (rhBMP-2) in the cervical spine.
We undertook a radiological and clinical review of cervical fusions performed at our institution with polyetheretherketone (PEEK) interbody cage and rhBMP-2.
Perioperative clinical and radiologic data of all patients who underwent an anterior cervical discectomy and fusion using PEEK and rhBMP-2 for cervical spondylotic radiculopathy or myelopathy were collected.
Images were examined for fusion, heterotopic ossification, end-plate resorption, subsidence, and segmental sagittal alignment.
All patients underwent detailed postoperative radiologic analysis using a computed tomography (CT) scan obtained at least 6 months postoperatively and plain X-rays obtained at regular intervals.
Twenty-two patients had 38 levels fused using PEEK and varying doses of rhBMP-2. No anterior cervical swelling requiring additional procedures or longer than anticipated hospital stays occurred. Pseudoarthrosis, shown as a horizontal radiolucent fissure through the midportion of the PEEK cage on CT, occurred in four patients. Excessive bone growth into the spinal canal or foramina occurred in 26 (68%) patients but did not result in neurologic sequelae. Cystic regions in the core of the PEEK spacer were seen in most patients, with 15 levels (39%) having cysts measuring 3mm or greater. Moderate or severe osteolysis of the end plates occurred in 57% of levels, and this led to subsidence of the construct and loss of some of the segmental sagittal alignment (ie, lordosis) that had been achieved with surgery.
The unlimited supply of PEEK spacers and rhBMP-2 and their ease of use make them attractive platforms to achieve fusion. This study has demonstrated that the fusion process using rhBMP-2 is a dynamic one, with osteolysis dominating the initial phase, leading to end-plate resorption and consequently loss of some of the disc space height and sagittal alignment that was achieved with surgery. There is a high incidence of bone growth beyond the core of the PEEK spacer and cystic regions within the cage. Given our experience, we currently reserve the use of PEEK and rhBMP-2 for use in those patients who are at greatest risk of pseudoarthrosis.
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ABSTRACT: Systematic review. To provide a systematic review of published literature on the impact of subsidence on clinical outcomes and radiographic fusion rates after anterior cervical discectomy and fusion with plates or without plates. Subsidence of interbody implants is common after anterior cervical spine fusions. The impact of subsidence on fusion rates and clinical outcomes is unknown. Systematic literature review on published articles on anterior cervical discectomy and fusion, which objectively measured graft subsidence, radiographic fusion rates, and clinical outcomes between April 1966 and December 2010. A total of 35 articles that measured subsidence and provided fusion rates and/or clinical outcomes were selected for inclusion. The mean subsidence rate ranged from 19.3% to 42.5%. The rate of subsidence based on the type of implant ranged from 22.8% to 35.9%. The incidence of subsidence was not impacted by the type of implant (P=0.98). The overall fusion rate of the combined studies was 92.8% and was not impacted by subsidence irrespective of subsidence definition or the measurement technique used (P=0.19). Clinical outcomes were evaluated in 27 of 35 studies with all studies reporting an improvement in patient outcomes postoperatively. Subsidence irrespective of the measurement technique or definition does not appear to have an impact on successful fusion and/or clinical outcomes. A validated definition and standard measurement technique for subsidence is needed to determine the actual incidence of subsidence and its impact on radiographic and clinical outcomes.Journal of spinal disorders & techniques 02/2014; 27(1):1-10. DOI:10.1097/BSD.0b013e31825bd26d · 1.89 Impact Factor
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ABSTRACT: Nationwide estimates examining Bone Morphogenetic Protein (BMP) use with cervical spine fusions have been limited to perioperative outcomes. Determined the one-year risk of complications, cervical revision fusions, hospital re-admissions and healthcare services utilization. A retrospective cohort study from 2002 to 2009 utilizing a nationwide claims database. There were 61,937 primary cervical spine fusions of which 1,677 received BMP. Complications, revision fusions, 30-day hospital readmission and healthcare utilization. Data for these analyses come from the Thompson Reuters MarketScan® Commercial Claims and Encounters Database © 2010. Patients were aged 18 to 64 receiving and not receiving BMP with a primary (C2-C7) cervical spine fusion. All outcomes were defined by ICD-9 and CPT codes. Complications were analyzed as any complication and stratified by nervous system, wound, and dysphagia or hoarseness. Cervical revision fusions were determined in the one-year follow-up. Hospital re-admission discharge records defined thirty-day hospital re-admission and reason for re-admission. The utilization of at least one healthcare service of cervical spine imaging, epidural usage or rehabilitation service was examined. Poisson regression models were used to estimate the relative risk (RR) and 95% confidence intervals (CI). Linear regression was used to determine time to hospital re-admission. Results were stratified by anterior or posterior and circumferential approach. Patients receiving BMP were 29% more likely to have a complication (adjusted relative risk [aRR]=1.29 ((95% CI 1.14 to 1.46)) and nervous system complication (aRR=1.42 ((95% CI 1.10 to 1.83)). Cervical revision fusions were more likely among patients receiving BMP (aRR=1.69 ((95% CI 1.35 to 2.13)). The risk of 30-day re-admission was greater with BMP use (aRR=1.37 ((95% CI 1.07 to 1.73)), and re-admission occurred on average 27.4% sooner. Patients receiving BMP were more likely to receive computed tomography scans (aRR=1.34 ((95% CI 1.06 to 1.70)) and epidurals with anterior surgical approaches (aRR=1.29 ((95% CI 1.00 to 1.65)). These findings question both the safety and effectiveness of off-label BMP use in primary cervical spine fusions.The spine journal: official journal of the North American Spine Society 12/2013; 14(9). DOI:10.1016/j.spinee.2013.11.042 · 2.80 Impact Factor
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ABSTRACT: Study Design. Retrospective study developing diagnostic criteriaObjectives. To validate two CT-based findings, extra-graft-bone bridging (ExGBB) and intra-graft-bone bridging (InGBB), as diagnostic criteria for anterior cervical fusion using subsequent surgical confirmation and to demonstrate the different diagnostic accuracy based on the graft material used.Summary of Background Data. The accuracy and methodology for evaluating bone bridging on CT scan to determine anterior cervical fusion status have not been validated or standardized.Methods. One-hundred-ten patients with 254 surgically explored segments along with reconstructed CT scans were included. Bone bridging at each cervical level was assessed for ExGBB and InGBB. ExGBB was defined as complete cortical bridging at any peripheral margins (anterior, posterior, left, or right) of the operated disc space, outside of the graft. InGBB was defined as cortical or trabecular bridging within the confines of the graft only. ExGBB and InGBB were serially evaluated on reformatted coronal and sagittal views by three independent raters. The reliabilities and validities correlated with surgical exploration were evaluated.Results. Surgical exploration revealed 123 fused and 131 pseudarthrosis segments. The reliability of three raters showed "near perfect" agreement for ExGBB and "substantial" agreement for InGBB. ExGBB also had higher validity for all raters than did InGBB. The auto-cortical graft group had the highest accuracy for both InGBB and ExGBB with both values being nearly identical. The allograft group had the next highest validity values. For the cage group, InGBB had the lowest specificity (53.2%) and positive predictive value(35.5%), whereas ExGBB had 100% sensitivity and negative predictive value.Conclusion. ExGBB appears to be a far more reliable and accurate to determine anterior cervical fusion and bone bridging patterns as diagnostic criteria should be different based on the intradiscal materials. With cages in particular, InGBB appears unreliable and ExGBB is necessary to determine anterior cervical fusion.Spine 09/2013; 38(25). DOI:10.1097/BRS.0000000000000017 · 2.45 Impact Factor