How does the ossification area of the posterior longitudinal ligament progress after cervical laminoplasty?

Study Design. Retrospective case series. Objective. To investigate the progression pattern of ossification of the posterior longitudinal ligament (OPLL) after cervical laminoplasty. Summary of Background Data. OPLL is a progressive disease, and an increased area of ossification affects the surgical results after laminoplasty. However, it is uncertain how the ossification area progresses with time after surgery. Methods. Fifty-five patients who were available for serial radiographs of more than 5 years were included. The extent of ossification in the longitudinal axis was assessed using computer software. The associations between the progression of OPLL and the clinical and radiologic data were analyzed. Results. Forty-one patients had OPLL progression. The patients were divided into three groups according to the pattern of progression. Group 1 consisted of patients 40 to 49 years of age with continuous or mixed type, showing slow progression at the beginning, then fast. Group 2 consisted of patients older than 50 years with continuous or mixed type, showing rapid progression at the beginning and then slow. The patients in Group 3 had segmental type with no or slight progression. Conclusions. We speculated that the progression of OPLL decreases as the patient ages. These findings will be important for the management of patients with OPLL after surgery.