Anterior Cervical Interbody Fusion Using a Polyetheretherketone (PEEK) Cage Device and Local Autograft Bone
Twenty-eight patients reported presurgery tobacco use. Although all tobacco-using patients agreed to cease use in the perioperative period, at least 9 admitted to resuming tobacco use immediately after surgery. Eighteen patients had diabetes mellitus. In 2 patients, a diagnosis of osteoporosis was made with dual-energy X-ray absorptiometry. One patient was a chronic user of steroids before and after surgery. Mean body mass index (BMI) was 30.6, and 13 patients were morbidly obese (BMI > 34).
In 2 cases, only a single blade was placed. The second blade could not be placed because of broken adjacent screws (1 case) or undetermined reason (1 case).
The mean time for follow-up was 17 months (range 3-34). Four patients were lost to follow-up: 3 after the 1-month postoperative visit and 1 with severe psychiatric problems after hospital discharge.
There were no new neurologic deficits, no wound infections, and no recurrent laryngeal nerve palsies in the 77 patients. Eight months after surgery, 1 patient with radiculopathy underwent foraminotomy at the index level for persisting foraminal stenosis. Two patients whose myelopathic symptoms persisted after surgery returned for minimally invasive posterior laminotomy to remove infolded ligamentum flavum. The presurgery and 3- and 9-month postsurgery NDI scores were available for 52 patients (Table 2). Before surgery the mean NDI score was 24 (range 8-40). Three months postsurgery the mean NDI score was 15 (range 2-27) for patients with myelopathy and 13 (range 2-28) for patients with radiculopathy. The patient with the highest NDI score (28) stated that though all his symptoms were relieved, he had gauged his responses to protect his disability claim. Nine months after surgery, the mean NDI scores were 9.5 (range 5-17) for patients with myelopathy and 6 (range 2-13) for patients with radiculopathy. No NDI score was higher postsurgery than presurgery.
Arthrodesis was defined as bony bridging between the adjacent vertebral bodies and the bone graft within the lumen of the device, anterior to the device, or posterior to the device. In Dr. Ross’ protocol, computed tomography (CT) scans or flexion-extension radiographs were obtained only if pseudarthrosis was suspected to avoid unnecessary radiation exposure. Sixty-six patients had at least the 3-month radiography follow-up available. All 52 patients with 9-month follow-up data achieved complete arthrodesis, as determined by plain film radiography. Bridging ossification was found anterior to the device in all but 9 patients. Trabeculated bone was growing through the lumen of the device in all cases (Figure 2). A broken blade without clinical correlation was noted on imaging for 1 patient.
The total cost of the ROI-C cervical cage (LDR) for VAPORHCS was $3,498, or $1,749 for the PEEK spacer plus $1,749 for 2 metal blades. In comparison, the total cost of a typical anterior locking plate would have been $6,700, or $3,200 for the plate plus $2,000 for 4 screws and $1,500 for an allograft fibular spacer. Demineralized bone matrix (1 mL) as used in cervical arthrodesis by other surgeons at VAPORHCS cost $279, or about $500 including shipping.
DISCUSSION
Anterior cervical discectomy with fusion is a very common and successful surgical procedure for cervical myelopathy, radiculopathy, and degenerative disease that has failed to be corrected with conservative therapy.10 Medicare data documented a 206% increase in 1-level fusion procedures for degenerative spine pathology performed between 1992 and 2005.11 When a procedure is performed so often, it is appropriate to review methods and analyze efficacy, cost, and cost-effectiveness.
According to a 2007 meta-analysis, the fusion rates of 1-level ACDF arthrodesis at 1-year follow-up are 97.1% in patients treated with anterior plates and 92.1% in patients treated with noninstrumented fusion.12 The rate disparity was larger for multiple-level fusion: 50% to 82.5% for instrumented cases12,13 vs 3% to 42% for noninstrumented cases.14-16 Given the higher fusion rates achieved with instrumentation, surgeons have favored its use in ACDF.
Computed Tomography Use
Computed tomography has long been considered the gold standard for assessing arthrodesis outcomes (eg, Siambanes and Mather).17 However, recent data on potential harm caused by CT-related ionizing radiation suggest a need for caution with routine CT use.18,19 For cervical spine CT, Schonfeld and colleagues found that the risk for excess thyroid cancers ranged from 1 to 33 cases per 10,000 CT scans.20 According to another report, “limiting neck CT scanning to a higher risk group would increase the gap between benefit and harm, whereas performing CT routinely on low-risk cases approaches a point where its harm equals or exceeds its benefit.”19 As some have questioned even routinepostoperative use of radiation in patients with unremarkable clinical courses—patients should be spared unnecessary exposure—CT scans or flexion-extensionradiographs were obtained at VAPORHCS only if clinical symptoms or radiographs were suggestive of pseudarthrosis.21 As none of the VAPORHCS patients had those symptoms, none underwent postoperative CT.
