ObjectiveTo report an improved classification system of Kümmell’s disease and its clinical application.MethodsBased on CT and MRI, an improved classification system of Kümmell’s disease was proposed in terms of the integrity of sagittal endplate, the integrity of posterior wall of vertebral body, and the degree of vertebral compression. Between January 2011 and March 2018, the improved classification system was used to evaluate and guide the treatment of 78 patients with Kümmell’s disease. There were 13 males and 65 females. The mean age was 69.1 years (range, 54-85 years). The mean disease duration was 4.0 months (range, 1-8 months). The mean T value of bone mineral density was −3.66 (range, −3.86- −3.34).The fractures located at thoracic vertebrae in 47 cases and lumbar vertebrae in 31 cases. According to the modified classification system of Kümmell’s disease, there were 11 cases of type A1, 13 cases of type A2, 2 cases of type A3, 10 cases of type B1, 18 cases of type B2, 4 cases of type B3, 4 cases of type C1, 5 cases of type C2, and 11 cases of type C3. According to the classification results, the patients of types A and B were treated with percutaneous kyphoplasty (PKP), while the patients of type C were treated with PKP or intra- vertebral fixation according to the degree of vertebral reduction. Visual analogue scale (VAS) score and Oswestry Disability Index (ODI) were used to evaluate clinical efficacy. The heights of the anterior, middle, and posterior edges of the vertebrae and the Cobb angle were measured to evaluate the reduction of the injured vertebrae and the improvement of kyphosis deformity. The complications were recorded.ResultsThe statistical analysis showed that the improved classification system has good consistency. All patients were followed up 12-36 months (mean, 24.3 months). The heights of anterior, middle, and posterior edges of the vertebrae, Cobb angle, VAS score, and ODI of all types of patients at last follow-up showed significant differences when compared with those before operation (P<0.05). After operation, 4 patients of type A2 had different degree of vertebral height loss; 2 patients of type B2, 3 patients of type C1, and 2 patients of type C2 developed asymptomatic bone cement leakage during PKP; 2 patients of type B3 and 3 patients of type C2 underwent percutaneous internal fixation and vertebral augmentation due to bone cement loosening.ConclusionThe modified classification system of Kümmell’s disease can be used to guide treatment of Kümmell’s disease, but the number of clinical application cases is limited, and further application and observation are needed.