Trends in Spinal Surgery Performed by American Board of Orthopaedic Surgery Part II Candidates (2008 to 2017)

Introduction: The American Board of Orthopaedic Surgery (ABOS) Part II Oral Examination is typically taken two calendar years after fellowship completion. Despite previous studies using ABOS Part II Oral Examination data in other subspecialties, types of cases performed by spine surgeons in initial independent practice have not been well-studied. Such data may help trainees anticipate case composition observed in early practice and allow spine fellowship programs to understand emerging trends.

Methods: We retrospectively reviewed surgical cases submitted to the ABOS by candidates taking the Part II Oral Examination between 2008 and 2017 whose designated subspecialty was spine. A hierarchical, restrictive algorithm was used to determine procedures based on candidate-reported International Classification of Diseases 9th/10th Revision and Current Procedural Terminology codes. Adjusted multivariable Poisson regression analyses were used to assess changes in procedure incidence rates over time.

Results: We identified 37,539 cases, averaging 3,754 cases/yr, and an average of 49 cases per candidate per 6-month collection period. The most common procedures were lumbar diskectomy (22% of all procedures), posterolateral spinal fusion (PSF) (19%), and anterior cervical diskectomy and fusion (ACDF) (17%). Rates of ACDF and cervical disk arthroplasty significantly increased over time (incidence rate ratios of 1.41 and 23.3 times higher, respectively, at the end of the study period), whereas rates of cervical foraminotomy, lumbar diskectomy, PSF, and structural autograft use decreased (incidence rate ratios of 0.35, 0.84, 0.55, and 0.30). Rates of anterior lumbar interbody fusion/lateral lumbar interbody fusion and transforaminal lumbar interbody fusion did not significantly change over the study period.

Discussion: Recent spine fellowship graduates are performing more cervical disk arthroplasties and ACDFs while decreasingly using structural autograft as well as performing fewer PSFs and lumbar diskectomies. Techniques such as anterior lumbar interbody fusion/lateral lumbar interbody fusions and transforaminal lumbar interbody fusions have not changed significantly over the last decade.

Level of evidence: Level IV (retrospective case series study).