Cervical Disc Displacement in Military Pilots

Introduction: Cervical disc displacement (CDD) may disqualify pilots from flying and have a profound impact on military unit capability. The objective of this retrospective database review is to characterize the incidence and demographic predictors of symptomatic cervical spine disc displacement in pilots of fixed- and rotary-wing aircraft and ground-based controls. Materials and Methods: The Defense Military Epidemiology Database was queried for first-occurrence ICD-9 code 722.0: CDD cases from 2007 to 2015. Injury count rates among aircraft groups and overall incidence per 1, 000 person-years were calculated and standardized for age, gender, and military rank, and 95% confidence intervals (CIs) were compared to determine significance. Results: There were 934 new cases of CDD among active duty U.S. Military pilots during the study period. The overall incidence of CDD in all pilots during this time frame was 2.715 per 1, 000 person-years (95% CI, 2.603-2.830). Helicopter pilots had a significantly higher incidence compared to all other aircraft pilots and crew at 3.79 per 1, 000 person-years (95% CI, 3.48-4.13). This finding remained statistically significant after standardizing for age, gender, and rank. Among all military officers, increasing age was a risk factor for CDD. Conclusions: The U.S. Military helicopter pilots have an increased risk compared to fixed-wing pilots and non-pilot controls. CDD remains a rare, though career-threatening, condition. Increased education and awareness training are warranted for both helicopter pilots and flight physicians to recognize signs and symptoms of cervical pathology. Continued investigations into preventive measures to minimize injury and time unfit for flight are warranted.