774 Adjacent-segment Disease after Anterior Cervical Fusion: A Review of 70 Reoperated Cases

Abstract

INTRODUCTION: Cervical spine motion segments adjacent to a fused segment are prone to undergo accelerated degenerative changes. However, published literature on additional anterior cervical fusions for adjacent-segment disease is lacking. We reviewed our experiences with reoperated cases for symptomatic adjacent-segment degeneration after anterior cervical disectomy and fusion (ACDF). METHODS: A retrospective study of 928 consecutive ACDF cases over the past 8 years showed that 70 were reoperations for symptomatic adjacent-segment disease. Age ranged from 35 to 65 years. Thirty-six patients were female, and 34 were male. Segment levels, location, and time frame and symptoms were analyzed. RESULTS: Of the index surgery, the most common level was single-level C5–C6 (29%), followed by C6–C7 (21%). Nineteen patients (27%) underwent a two-level fusion (7 had C4–C5 and C5–C6, 10 had C5–C6 and C6–C7, and 2 had C6–C7 and C7–T1). Seven (10%) had a three-level fusion. Adjacent-level degeneration requiring additional fusion occurred at C6–C7 (14 patients), C5–C6 (14 patients), C4–C5 (11 patients), C3–C4 (9 patients), C7–T1 (3 patients), two-level (16 patients), and three-level (3 patients). Isolated superior segment, inferior segment, superior and inferior segment, and remote degeneration occurred in 57%, 29%, 10%, and 4%, respectively. Nine cases showed junctional instability evidenced by flexion/extension films. Time frame from the index surgery to the reoperation ranged from 9 months to 27 years (average, 6.75 yr) with a bimodal distribution, the first peak of less than 3 years (31%) and second peak of greater than 10 years (19%). CONCLUSION: Symptomatic adjacent-segment disease requiring additional fusion involves the superior segments twice as commonly as the inferior segments. Average time between the index ACDF and the adjacent-segment additional fusion is 6.7 years, with a bimodal distribution (less than 3 years and greater than 10 yr). Single-level arthrodeses at C5–C6 and C6–C7 are the most common levels involved in the index surgery.