Adjacent segment disease: Incidence and recommended treatment

The incidence, etiology, and treatment of adjacent segment pathology in the cervical spine have been one of the most researched topics in the past 15 years. Despite the abundance of literature many questions about the phenomenon remain unanswered. The three leading theories regarding etiology consist of altered biomechanics from adjacent fused segments, natural disease history, and soft-tissue disruption. All of the theories have evidence to support them but none can entirely explain the condition. Similarly, the true incidence of adjacent disease remains difficult to define secondary to heterogeneous patient populations, diagnostic methods, and surgical procedures. Anterior cervical discectomy and fusion is the most common surgical procedure for cervical pathology and as such the majority of the data on adjacent segment problems originates from ACDF literature. A large impetus for the development of cervical disc arthroplasty was to decrease adjacent pathology rates associated with anterior cervical fusion. However, while disc arthroplasty is clearly an effective treatment for certain cervical conditions, its effect on adjacent segment pathology are uncertain and longer-term follow-up is needed. The treatment for adjacent segment pathology should be approached similar to that of a patient presenting with primary symptoms. Anterior cervical fusion and disc arthroplasty, as well as, posterior-based options such as laminoplasty and laminectomy with fusion have been successfully used for adjacent problems. Ultimately, adjacent segment pathology is a reality of managing cervical spine conditions regardless of the chosen treatment. Surgeons should council patients accordingly about their individual risk factors and be prepared to manage adjacent pathology as a routine part of spine practice.