Anterior Cervical Discectomy and Fusion: The Surgical Learning Curve

Case-series OBJECTIVE.: The aim of the study was to investigate changes in intraoperative and postoperative parameters associated with the surgical learning curve for anterior cervical discectomy and fusion (ACDF).

ACDF is a common surgical spine procedure. The surgical learning curve for this procedure has not been previously characterized.

A prospectively maintained surgical database of consecutive patients who underwent primary 1-2 level ACDF for degenerative spine disease from 2006 to 2014 was reviewed. Patients with concurrent or revision procedures were excluded. The series began after the surgeon's fellowship and includes his first case as an attending. A total of 374 patients were divided sequentially into cohorts of 125 (early), 125 (middle), and 124 (late). Statistical analyses utilized independent sample t tests, chi squared tests, and multivariate regression adjusted for preoperative characteristics. The learning curve of operative time was characterized using three-parameter asymptotic regression and two separate linear regressions.

The earliest cohort had a greater comorbidity burden, percentage of smokers, and Medicare patients, with fewer workers' compensation patients when compared to later cohorts. Later cohorts demonstrated decreased mean operative time and estimated blood loss (EBL) and increased arthrodesis rate. Asymptotic and linear regression analyses demonstrated that 50% of the learning curve occurred at case 17 and 31, respectively, whereas 90% of potential improvement occurred by case 56 and 57, respectively.

A significant learning curve exists for surgeons performing ACDFs. Patients undergoing ACDF will experience shorter operations, less EBL, and greater arthrodesis rates as the surgeon gains experience. Operative proficiency can be expected to occur by case 60, with arthrodesis rate increasing over a longer period. These results suggest that despite longer operative times and increased EBL with earlier cases, ACDF can safely and effectively be performed at the onset of a surgeon's career. This conclusion may be useful to new surgeons debating between operative and nonoperative management of cervical degenerative disc disease.

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