Healthcare burden changes by restricted physical activities in lumbar spinal stenosis and spondylolisthesis: a retrospective large cohort study during the COVID-19 pandemic. - Kim, Jun-Hoe; Chegal, Yebin; Kim, Suhyun; Park, Hangeul; Kim, Young Rak; Kim, Sum; Kim, Kwangsoo; Lee, Chang-Hyun; Kim, Chi Heon; Chung, Chun Kee (BMC Musculoskeletal Disorders, 2024)