Impact of obesity on cervical ossification of the posterior longitudinal ligament: a nationwide prospective study

Positive association between ossification of the posterior longitudinal ligament of the spine (OPLL) and obesity is widely recognized; however, few studies focused on the effects of obesity on treatment of cervical OPLL. The effects of obesity on surgical treatment of cervical OPLL were investigated by a Japanese nationwide, prospective study. Overall, 478 patients with cervical myelopathy due to OPLL were prospectively enrolled. To clarify the effects of obesity on the surgical treatment for cervical OPLL, patients were stratified into two groups, non-obese (< BMI 30.0 kg/m(2)) and obese (≥ BMI 30.0 kg/m(2)) groups. The mean age of the obese group was significantly younger than that of non-obese group. There were no significant differences between the two groups in other demographic information, medical history, and clinical and radiographical findings. Alternatively, the obese group had a significantly higher rate of surgical site infection (SSI) than that of non-obese group. Approach-specific analyses revealed that the SSI was significantly higher in the obese group than in the non-obese group. A logistic regression analysis revealed that age, BMI, and duration of symptoms were significant factors affecting the postoperative minimum clinically important difference success. The result of this study provides useful information for future cervical OPLL treatment.