Efficacy of an allograft cellular bone matrix as an alternative to autograft in anterior cervical discectomy and fusion: radiological results & safety

Abstract

Background: The predominant surgical procedure employed for patients with symptomatic cervical radiculopathy is anterior cervical discectomy and fusion (ACDF). ACDF typically involves the use of an interbody cage augmented with iliac crest bone graft (ICBG) or local autograft to enhance fusion rate. Substantial complications can arise from autograft use, including donor site morbidity, difficulties with ambulation, and diminished quality of life. This study aims to evaluate the effectiveness and safety of an allograft cellular bone matrix (ACBM) as an osteopromotive bone, in ACDF procedures.

Methods: This retrospective, single-center, consecutive case series included 73 patients who underwent an ACDF procedure. The surgical procedure involved the placement of an interbody cage supplemented with anterior plate fixation and an ACBM within the interbody spacer. Patient charts were reviewed to gather demographic information, radiographic findings, as well as perioperative and post-operative complications. Radiographic fusion was assessed at 6 and 12 months by a blinded, musculoskeletal-trained radiologist and a board-certified spinal surgeon reviewer. Any discrepancies were settled by a third, senior reviewer. Complete fusion was defined as: evidence of bridging bone across the disc space on CT, angular motion <3 degrees, and translational motion <2 mm on lateral radiographs. Complications were analyzed at 6, 12, and 15+ months post-operatively to assess clinical outcomes and device performance.

Results: A total of 73 patients (50 males, 23 females) with an average age of 54.6 (range, 31-77) years underwent an ACDF procedure between C3-T1 with an ACBM. The breakdown of levels operated on was 26%, 32%, 34%, and 8% for one, two, three, and four level procedures, respectively. There were three patients who received spinal injections for pain within the first year post-operatively. There were two patients who required secondary surgery within the first 12 months where supplemental posterior hardware was needed. Notably, there were no instances of cage subsidence, cage migration, cage/graft removal, or reoperation. There were no cases of chronic dysphasia. At 6 months, 45% of patients with available imaging demonstrated complete fusion, while 97.4% of patients with available imaging demonstrated complete fusion at 12 months.

Conclusions: At the 12-month follow-up, our study demonstrates a high fusion rate in a real-world population of up to 4 operative levels. There were no bone graft related complications or incidences of cage migration/subsidence. It is noteworthy that the study involved a significant number of multilevel cases (74% of cases). Despite this, our results align with historical fusion rates and provide support for the utilization of ACBMs as a fusion adjunct in ACDF procedures up to 4 levels.

Keywords: Anterior cervical discectomy and fusion (ACDF); allograft; cellular bone matrix; cervical spine; spinal fusion.

Figure 1

Distribution of one, two, three, and four level ACDF cases in our cohort. ACDF, anterior cervical discectomy and fusion.

Figure 2

Percentage of patients with available imaging (n=69) who demonstrated fusion at 6 months, stratified by number of levels operated on.

Figure 3

Percentage of patients with available imaging (n=39) who demonstrated fusion at 12 months, stratified by number of levels operated on.

Figure 4

Radiographic progression of a 3-level fusion. (A) Preoperative CT scan; (B) 5-month post-operative CT scan; (C) final post-operative sagittal view CT scan; (D) final post-operative coronal view CT scan depicting successful fusion for a 49-year-old male, nonsmoker, who underwent a 3-level ACDF procedure with symptomatic relief. CT, computed tomography; ACDF, anterior cervical discectomy and fusion.

Figure 5

Radiographic progression of a primary 4-level ACDF with a secondary procedure for supplemental fixation. (A) Pre-operative CT scan; (B) 6-month post-operative CT scan. At 8 months post-operatively, the patient reported recurrent neck and upper extremity pain with a possible pseudoarthrosis at C6–C7 seen on imaging. At 11 months post-operatively, posterior supplemental fixation with lateral mass screws was added at C6–C7; (C) 16 months (5 months post-operative from second surgery) sagittal view CT scan; (D) 16-month post-operative coronal view CT scan depicting successful fusion for a 54-year-old non-smoker after secondary surgery. ACDF, anterior cervical discectomy and fusion; CT, computed tomography.