Anterior Plate-Screws and Lower Postoperative T1 Slope Affect Cervical Allospacer Failures in Multi-Level ACDF Surgery: Anterior Versus Posterior Fixation

Abstract

Study Design: Prospective observational study. Objective: In ACDF, graft failure and subsidence are common complications of surgery. Depending on the cervical fixation, different biomechanical characteristics are applied on the grafts. This aims to describe the incidence of cervical spacer failure in patients with cervical degenerative condition according to the cervical fixation method and sagittal balance. Method: From November 2011 to December 2015, 262 patients who underwent cervical spine surgery were enrolled prospectively. Patients were divided into 3 groups based on fixation method: anterior plate/screw (APS), posterior lateral mass screw (LMS), pedicle screw (PPS) groups. Serial X-rays and CT scans were utilized to evaluate radiologic outcomes. Results: Mean patient ages were 56.1 years in the APS group, 61.5 years in the LMS group, and 57.6 years in the PPS group ( P = 0.002). Allospacer failure was most common in the APS group, compared to the LMS and PPS groups (chi-square, P = 0.038). Longer fusion level was associated with greater allospacer failure (Baseline 2 level surgery; Odds ratio (OR) 3.4 in 3 level, 15.2 in 4 level, P = 0.036,0.013). Higher T1 slope was correlated with less allospacer failure (OR 0.875, P = 0.001). ORs of allospacer failure in the LMS and PPS groups were 0.04 and 0.02, respectively, ( P = 0.01, 0.01), compared with the APS group. Conclusion: This study was able to show that allospacer failure in multi-level ACDF surgery is more common with a longer fusion length, less postoperative T1 slope, and an anterior plate-screws technique. Pedicle screws provided the best biomechanical stability among the 3 constructs.

Morphologic Change of Cortico-Cancellous Allograft used for Anterior Cervical Discectomy and Fusion

“…Suk et al demonstrated that allospacer failure commonly occurs at a location where the allograft is not protected by plate or screw fixation. 37 Furthermore, Lee et al suggested that using a screw length that is > 75% of the vertebral body length is needed to decrease pseudarthrosis. 38 Second, choosing an appropriate graft height to avoid overdistraction is needed.…”

Variation in Prevertebral Soft Tissue Swelling after Staged Combined Multilevel Anterior–Posterior Complex Cervical Spine Surgery: Anterior Then Posterior (AP) versus Posterior Then Anterior–Posterior (PAP) Surgery

“…This slightly flexed posture of the neck lengthened the posterior cervical muscles, thereby making its depth shallower, and thus, performing the anterior surgery after the posterior surgery made positioning the neck in that manner more convenient. PAP surgery also was favorable if an all-pedicle screw construct was preferred, especially in patients with osteoporosis, severe deformity, and large enough pedicles (≥3.5 mm) [ 6 , 16 , 17 ].…”

Handgrip Strength Correlated with Falling Risk in Patients with Degenerative Cervical Myelopathy

“…As the general condition of the patients is related to the preoperative and postoperative recovery of function, the overall condition of the patients is an important factor [ 42 , 43 ]. Additionally, we included more severe spondylotic myeloradiculopathic cases that had undergone combined anterior–posterior surgery [ 44 , 45 , 46 ], and as such the rate of combined anterior–posterior surgeries was much higher than that in another study [ 5 ]. Moreover, we report not only actual falls but also the objective measures of functional mobility tests and HGS, which all affect patient subjective symptoms.…”