Comparison between osteonecrosis of the humeral and femoral heads - epidemiological analysis of the surgical trend using the nationwide claims database of the republic of Korea

BACKGROUNDS: The humeral head is the second most common site of osteonecrosis, after the femoral head. However, compared to osteonecrosis of the femoral head (ONFH), epidemiological information on osteonecrosis of the humeral head (ONHH) is scarce. We hypothesised that different biomechanical properties of the shoulder from the hip joint might present different epidemiological characteristics of ONHH from those of the ONFH. To evaluate epidemiological differences, we compared trends in the surgical treatment of ONHH and ONFH using the nationwide medical claims database of the Republic of Korea (ROK). METHODS: We analysed epidemiological data from the Health Insurance Review and Assessment (HIRA) database of the ROK between 2008 and 2018. HIRA database contains almost all medical information in an anonymised form, including demographics, diagnoses, and types of surgical procedures, generated through healthcare practices in ROK. The annual incidence rates of ONHH and ONFH were calculated based on the total number of the general population. Demographics, annual incidence, and the proportion of post-traumatic osteonecrosis and surgical procedures were compared according to the anatomical site and the affected year. RESULTS: The total number of patients treated for ONHH and ONFH during the study period was 1,028 and 66,260, respectively. Although the incidence of ONHH increased, it is a relatively rare disease compared to ONFH. ONHH occurred more frequently in females, while ONFH occurred predominantly in male patients (p < 0.001). Surgical treatment for ONHH was most frequently performed in older patients (63.7%), whereas middle-aged patients had the largest proportion of ONFH (48.9%, p < 0.001). The proportion of post-traumatic osteonecrosis was significantly higher in the ONHH (5.1%) than in the ONFH (1.9%, p < 0.001). Arthroplasty was performed more frequently in the ONHH (96.0%) than in the ONFH (92.9%, p < 0.001). CONCLUSION: Despite the anatomical similarities between the hip and shoulder joints, the different biomechanical properties, such as weight-bearing functions, might cause epidemiological differences between ONHH and ONFH.