Purpose Coronavirus disease (COVID-19) lockdowns have impacted on management of osteoporosis and the use of telemedicine is increasingly widespread albeit supported by little evidence so far. The aim of the study is to assess adherence to denosumab and incidence of non-traumatic fractures during the lockdown compared to the pre-COVID-19 year and to explore the effectiveness of telemedicine in the management of osteoporotic patients. Methods Retrospective, longitudinal, single-center study on patients receiving subcutaneous denosumab therapy every 6 months. Each patient was scheduled to undergo 2 visits: one during the pre-COVID-19 period (March 2019-March 2020) and another visit during the lockdown period (March 2020-March 2021). Data on new fractures, adherence, risk factors for osteoporosis and the modality of visit (telemedicine or face-to-face) were collected. ResultsThe prevalence of non-adherent patients was higher during the lockdown (35 of 269 patients, 13.0%) than the pre-COVID-19 period (9 of 276 patients, 3.3%) (p < 0.0001). During the lockdown, the number of new non-traumatic fractures was higher than the pre-COVID-19 year (p < 0.0001): 10 patients out of 269 (3.7%) experienced a fragility fracture and 2 patients (0.7%) a probable rebound fracture during the lockdown period, whereas no patient had fragility/rebound fractures during the pre-COVID-19 period. No difference was found in the prevalence of non-adherence and new non-traumatic fractures comparing patients evaluated with tele-medicine to those evaluated with face-to-face visit. Conclusion Non-adherent patients and new non-traumatic fractures (including rebound fractures) were more prevalent during the lockdown in comparison to the pre-COVID-19 period, regardless of the modality of medical evaluation.