Clinical study
Fusion rate following three- and four-level ACDF using allograft and segmental instrumentation: A radiographic study

https://doi.org/10.1016/j.jocn.2018.11.040Get rights and content

Highlights

  • Pseudarthrosis rates of extended anterior cervical fusion (3- and 4-level) are under-reported.

  • The minority of radiographic pseudarthrosis are clinically symptomatic.

  • Pseudarthrosis rates are higher in 4-level than 3-level ACDF.

Abstract

Cervical spine degenerative pathologies remain one of the most common spinal conditions treated by spine surgeons worldwide. Surgery is recommended in all patients with symptomatic cervical spinal stenosis with either moderate to severe myelopathy, degeneration, or refractory radiculopathy. As the number of levels increases the potential for complications associated with anterior surgery can be significant, especially dysphagia and pseudarthrosis. The objective of this study was to analyze the fusion rate following three- or more level anterior cervical discectomy and fusion (ACDF). A retrospective review was performed analyzing patients who underwent three or more level ACDF. Fusion was evaluated using post-operative dynamic upright radiographs Relevant post-operative complications especially dysphagia requiring dietary modifications or placement of feeding tube was also noted. A total of 72 patients were included in the study. Of the 232 levels fused, pseudarthrosis occurred at 47 (14%) levels. Overall 45.8% of patients (33/72) had a pseudarthrosis. The incidence of pseudarthrosis was higher in patients with 4 level ACDF as compared to those with 3 level ACDF [56% (9/16) versus 42% (24/56)]. At last follow up, the number of patients that were symptomatic from their pseudarthrosis and required posterior spinal instrumentation was 8/72 (11.1%). Fusion rates in a large cohort of patients with three- and four-level ACDF performed utilizing allograft and segmental instrumentation is reported. The study demonstrates that 3–4 level, stand-alone anterior cervical arthrodeses result in at least one level of pseudarthrosis in almost half of patients, especially at the caudal level of the construct.

Introduction

Symptomatic multi-level degenerative changes with associated myelopathy in the cervical spine is an increasingly common entity [5]. It has been demonstrated in a number of studies that surgical decompression of the cervical spinal cord is an effective treatment option for patients with refractory radiculopathy, severe degenerative disease, or moderate to severe cervical spondylotic myelopathy (CSM) that not only halts the progression of symptoms, but can also promote meaningful functional recovery in a significant portion of treated individuals [6], [17]. Both anterior and posterior approaches are effective in addressing pathology in patients with CSM. In fact, a recent systematic review by the American Association of Neurological Surgeons (AANS) and the Congress of Neurological Surgeons (CNS) concluded that both anterior [Anterior cervical discectomy and fusion (ACDF), Anterior cervical corpectomy and fusion (ACCF)] and posterior approaches (laminoplasty, laminectomy, and laminectomy with fusion) all yielded similar near term functional improvements in patients with CSM [11]. The choice of surgical approach is dependent on multiple factors, including age, general medical status, and comorbidities, cause of compression, primary site of compression, number of levels involved, as well as sagittal alignment of the spine. Anterior approaches are generally preferred when restoration of cervical lordosis is a primary surgical goal. With studies showing suboptimal correction of sagittal imbalance in posterior procedures as compared to anterior approaches, there may be increasing application of anterior approaches for patients with multilevel CSM [14]. Even though multilevel ACDF is a commonly performed surgery, the potential for complications associated with anterior approaches is not negligible, especially dysphagia and pseudarthrosis.

While there is a significant data regarding fusion rates and complications in one- or two-level anterior cervical discectomy and fusions (ACDF), the literature on fusion rates following 3 or more level ACDF particularly using allograft is sparse with variable rates of pseudarthrosis [1], [10], [15], [18], [20]. The pseudarthrosis rates following three- and four-level anterior fusion rates have been reported between 0 and 40% depending on graft type, the use of bone morphogenetic protein (BMP), and the presence of anterior cervical plating [2], [10], [12], [21]. With the increasing number of multilevel ACDFs, it is critical to be aware of overall fusion rates to allow preoperative patient counseling and selection of optimal surgical approach for patients with multilevel cervical spine pathologies. This study reports fusion rates following three- and four-level ACDF using allograft and segmental instrumentation from a single institution.

Section snippets

Methods

A retrospective review was performed to analyze the medical records of all patients who underwent three or more level ACDF procedures with plating from 2009 to 2013 at a major tertiary care academic medical center. The study was approved by the Institutional Review Board. A minimum radiological follow-up of at least 12 months or an earlier need of revision surgery for pseudarthrosis was required for the patient to be enrolled in the study. Standard demographics and clinical variables including

Results

A total of 72 patients met inclusion criteria for the study with demographics as detailed in Table 1. Of the 232 levels operated upon, pseudarthrosis occurred at 47/232 (20.3%) levels. Overall 45.8% of patients (33/72) had a pseudarthrosis, most commonly at the caudal level of the construct. Illustrative examples of pseudarthrosis can be seen in Fig. 1, Fig. 2. Subgroup analysis revealed that the incidence of pseudarthrosis was higher in patients with a 4-level ACDF compared to those with a

Discussion

While ACDF has been shown to be an extremely effective surgery in appropriately selected patients, revision surgery after anterior fusion is sometimes necessary, with rates ranging from 2.1% to 9.3% for single-level procedures and 4.4% to 10.7% for multilevel procedures. The most common causes for revision surgery in this group of patients include adjacent segment disease, pseudarthrosis, progressive deformity, infection, or a combination of these [9]. The incidence of pseudarthrosis is not

Conclusion

The present study demonstrates the incidence of radiographic pseudarthrosis following 3 or more level ACDFs. Though only a minority of patients with pseudoarthrosis may be clinically symptomatic, the possibility of requiring some intervention over long term follow up remains. Alternative surgical strategies for patients at higher risk for pseudoarthrosis may be considered to decrease the incidence of pseudarthrosis following such multilevel ACDFs.

Source of funding

None.

Disclosures

Harel Deutsch reports receiving royalties from Pioneer.

John E. O’Toole reports being a consultant and receiving royalties for Globus Medical and Pioneer Surgical and has stock ownership in Theracell, Inc.

Vincent C. Traynelis is a consultant and receives royalties from Medtronic and receives institutional fellowship support from AO and Globus.

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