Prevalence and distribution of diffuse idiopathic skeletal hyperostosis in patients with thoracic ossification of the ligamentum flavum / 中华骨科杂志

ABSTRACT

Objective:To analyze the prevalence and distribution characteristics of diffuse idiopathic skeletal hyperostosis (DISH) in hospitalized patients with thoracic ossification of the ligamentum flavum (TOLF).Methods:The clinical records of 132 consecutive TOLF patients from January 2018 to June 2019 were retrospectively studied. DISH was identified by the preoperative X-ray and CT and its prevalence was calculated. The prevalence of patients with different genders, different age groups and different ossification types was compared. The segmental distribution of DISH and the distribution in the upper (T 1-T 4), middle (T 5-T 8), and lower thoracic spine (T 9-T 12) were analyzed. Ossification degree of DISH was evaluated based on the Meta scoring system. The demographic characteristics (age, gender, BMI, etc.) were compared between DISH and non-DISH group. Results:Forty-nine patients was diagnosed as DISH with the prevalence of 37.1% in all included cases. The prevalence was about twice as high in male (46.3%) than in female (23.1%) ( χ2=8.806, P=0.003). The prevalence in the age groups of <40, 40-49, 50-59, 60-69 and ≥70 years was 20.0%, 28.0%, 34.4%, 44.0%, and 66.7%, respectively. The prevalence in long-segment TOLF patients (45.1%) was significantly higher than that in short-segment TOLF patients (24.0%) ( χ2=5.937, P=0.015). DISH most frequently affected T 8,9 levels (91.8%). The total number and mean number of ossified segments were 365 and 7.4, respectively. Ossification lesions in the upper, middle, lower thoracic spine accounted for 26.03%, 40.54%, and 33.15%, respectively. Grade I, grade II, and grade III ossification accounted for 21.4%, 28.5% and 50.1%, respectively. The mean age of the DISH group was older than the non-DISH group ( t=2.024, P=0.045). The proportion of male patients in the DISH group was significantly higher than that in the non-DISH group ( χ2=8.806, P=0.003). The average height and weight in the DISH group were significantly greater than those in the non-DISH group ( t=2.564, P=0.012; t=2.191, P=0.030), whereas no significant differences in BMI and constituent ratio of concurrent diabetes, cardiac disease, hypertension between two groups were observed. Conclusion:The prevalence of DISH in patients with TOLF is 37.1%. Male, elderly and long-segment TOLF patients are associated with higher prevalence. DISH frequently occurs in the middle and lower thoracic spine, and T 8,9 is the common affected segment. Ossification lesions may develop with age. Demographic characteristics of DISH group differ, to some extent, from those of non-DISH group.