Adjacent Level Ossification Development Following Anterior Cervical Fusion: How Does it Affect the Next Level Disc?

• Published in: Spine (Philadelphia, Pa. 1976) Pa. 1976), 2020-11, Vol.45 (22), p.E1469-E1475
• Main Authors: Lee, Dong-Ho, Park, Sehan, Park, Jae-Woo, Hwang, Chang-Ju, Cho, Jae Hwan, Lee, Choon Sung, Riew, K. Daniel
• Format: Article
• Language: English
• Subjects: Adult; Cervical Vertebrae - diagnostic imaging; Cervical Vertebrae - surgery; Diskectomy - adverse effects; Diskectomy - trends; Female; Follow-Up Studies; Humans; Intervertebral Disc Degeneration - diagnostic imaging; Intervertebral Disc Degeneration - etiology; Male; Middle Aged; Ossification, Heterotopic - diagnostic imaging; Ossification, Heterotopic - etiology; Range of Motion, Articular - physiology; Retrospective Studies; Spinal Diseases - diagnostic imaging; Spinal Diseases - surgery; Spinal Fusion - adverse effects; Spinal Fusion - trends
• ISSN: 0362-2436; 1528-1159
• DOI: 10.1097/BRS.0000000000003656

STUDY DESIGN.Retrospective matched cohort analysis. OBJECTIVE.The aim of this study was to investigate the impact of adjacent level ossification development (ALOD) on the affected as well as the next-level discs with regards to range of motion (ROM) and degenerative changes. SUMMARY OF BACKGROUND DATA.Although ALOD is not a rare condition in patients who undergo anterior cervical fusion procedures, there has been little discussion to date about its clinical implications. METHODS.Patients who underwent anterior cervical instrumented fusion with a minimum 2-year follow-up were reviewed. Twelve patients with each respective ossification grade (totally 48 patients) were matched based on age, sex, and number of fusion levels. On the preoperative and final follow-up x-rays, disc height, osteophytes, ROM, and maximal listhesis were assessed at the segments which were one- (the adjacent segment) and two-level cranial (the next segment) to the uppermost fused disc. Then, the patients were divided into two groups according to ALOD degreegroup 1 (grade 0–1, N = 24) versus group 2 (grade 2–3, N = 24). The changes of all variables were compared between the two groups. RESULTS.The mean ROM of the adjacent segment increased by 3.6 degree in group 1 and conversely decreased by 2.8 degree in group 2 (P = 0.002). The mean ROM increase of the next segment was significantly greater in group 2 than in group 1 (4.5 vs. 1.2 degree, P = 0.016). The osteophyte growth and the progression of listhesis at the next segment were significantly greater in group 2 (P