Durability of Anterior Cervical Discectomy and Fusion: A Survivorship Analysis Based on Revision Surgery Rates.

INTRODUCTION

Durability of surgical treatment is important to patients, providers, and payers. In addition to the obvious effect on clinical outcomes and satisfaction, durability is an important variable when evaluating cost-effectiveness. The purpose of this study was to analyze the prevalence and indications for revision surgery after anterior cervical discectomy and fusion (ACDF).

METHODS

A multisurgeon, single-institution database was queried for revision surgery after ACDF from 2014 to 2018 with a minimum follow-up of 4 years (N = 1,652). Demographic data, surgical data, and primary indication for revision surgery were collected by medical record analysis. All statistical analyses were performed using IBM SPSS v28.0 (IBM).

RESULTS

A total of 147 of 1,652 patients (9%) underwent unplanned revision surgery during the study period. The mean patient age was 53.6 years; the mean number of surgical levels was 1.8. The most common indication for revision surgery was nonunion (N = 94, 6%), which occurred at a mean of 33 months postoperatively. The second most common indication was adjacent segment disease (N = 37, 2%), which occurred at a mean of 24 months postoperatively. Patients who had a revision surgery for nonunion had more levels fused (2.06) compared with patients who had no revision surgery (1.65) or had surgery for adjacent segment disease (1.76) ( P < 0.001). Likewise, patients with nonunion had longer surgical time ( P < 0.001) and length of stay ( P = 0.036). Patients who underwent a revision surgery for adjacent segment disease had a higher body mass index (BMI = 33.6) compared with patients without revision surgery (BMI = 30.4) or patients who underwent revision surgery for nonunion (BMI = 31.2) ( P = 0.012). Comorbidities as measured by ASA grade did not differ between groups ( P = 0.633). Smoking status, use of anterior plate, and use of structural allograft did not differ between groups ( P > 0.05). No other differences were found among these groups. Other indications for revision surgery were much less common (<1%) and included evacuation of hematoma (N = 5), repeat decompression (N = 5), infection (N = 2), extension into the thoracic spine (N = 2), and implant reposition (N = 2).

DISCUSSION: ACDF is a relatively durable procedure (91%) as currently indicated and performed in a large multisurgeon spine center. Early revision surgery (<90 days) for hematoma or infection is rare. Late revision surgery (>90 days) for nonunion is more than twice as common as adjacent segment disease and occurred earlier and more commonly when a greater number of levels were fused. These data can help guide clinicians and researchers in future quality improvement initiatives.