0.5- to 1-Fold Intervertebral Distraction Is a Protective Factor for Adjacent Segment Degeneration in Single-level Anterior Cervical Discectomy and Fusion

Abstract

Study Design. Retrospective analysis. Objective. This study aimed to compare the clinical and radiological outcomes of different degrees of distraction in anterior cervical discectomy and fusion (ACDF) and evaluate the risk factors for adjacent segment degeneration (ASD). Summary of Background Data. ASD is a common complication following ACDF. Inadequate distraction of the intervertebral space during surgery is associated with ASD; however, there is still an ongoing debate regarding what degree of distraction is appropriate. Methods. This retrospective study enrolled 130 patients who underwent single-level ACDF for cervical degenerative disc disease and were followed up at least 2 years. The patients were divided into the following three groups according to the degree of distraction (≤0.5, 0.5–1, ≥1): insufficient distraction group (ID group), appropriate distraction group (AD group), and excessive distraction group (ED group). The clinical outcomes and radiological parameters were evaluated before and after operation and at the last follow-up. Risk factors for ASD were identified through logistic regression analysis. Results. A significant difference was found in the Visual Analog Scale values between the AD group and ED group at the final follow-up. Moreover, the highest upper segmental disc height (DH), highest lower segmental DH, and lowest incidence of ASD were found in the AD group among the three groups at last follow up. Logistic regression analysis revealed that segmental kyphosis (odds ratio = 2.821, P = 0.020) was a risk factor for the occurrence of ASD and 0.5- to 1-fold distraction (odds ratio = 0.350, P = 0.025) was a protective factor. Conclusion. Good clinical and radiological outcomes were achieved in ACDF with 0.5- to 1-fold distraction. Segmental kyphosis is a risk factor for ASD in ACDF, whereas 0.5- to 1-fold distraction is a protective factor of ASD. Level of Evidence: 4

Cervical sagittal alignment after Prestige LP cervical disc replacement: radiological results and clinical impacts from a single-center experience

“…Normal sagittal alignment in the cervical spine plays important roles in attaining global spinal balance, transferring axial loads, and maintaining mobility [1,16]. In cervical arthrodesis, a change in SVA or T1s-CL has been shown to be related to worse clinical outcomes, as measured by the NDI score [3,4], and kyphotic SA has been shown to be a risk factor for ASD [5]; in addition, T1s has been shown to be a predictive factor for subsidence and pseudarthrosis [16]. However, whether these cervical sagittal parameters affect CDR is currently unknown.…”

“…Segmental kyphosis has been considered a risk factor for ASD in patients who undergo ACDF [5]. Lee et al reviewed 12 patients who underwent CDR and found that non-ASD patients had a more lordotic SA postoperatively than ASD patients [20].…”

“…According to the position of HO on the lateral radiographs, the patients were divided into the anterior heterotopic ossification (AHO) group and posterior heterotopic ossification (PHO) group [12]. ASD was considered to exist when one of the following criteria were met [5,13]: 1) new or enlarging osteophyte formation at the anterior or posterior border of vertebrae; 2) narrowing of the intervertebral disc space > 25%; 3) ossification of the anterior or posterior longitudinal ligament.…”

“…Previous studies have proven that after anterior cervical discectomy and fusion (ACDF), abnormal cervical sagittal alignment can affect patients' quality of life [1,3,4]. In addition, segmental kyphosis of the cervical spine increases the risk of adjacent segment degeneration (ASD) after ACDF [5]. However, whether the same outcomes occur after cervical disc replacement (CDR) remains unknown.…”

Association of cervical sagittal alignment with adjacent segment degeneration and heterotopic ossification following cervical disc replacement with Prestige-LP disc

“…Several studies have shown that the above cervical sagittal alignment parameters are associated with patient outcomes after anterior cervical spine surgeries, such as anterior cervical discectomy and fusion (ACDF). [6][7][8][9][10] For instance, poor CL and kyphotic FSUAs are risk factors for adjacent segment degeneration (ASD), 8,11,12 and a high T1s is associated with pseudarthrosis and implant subsidence following ACDF. 6,10 However, the relationship between cervical sagittal balance and other kinds of anterior cervical spine surgeries, such as cervical disc replacement (CDR), is poorly understood.…”