Management of Humeral Solitary Bone Cysts in Children Using Elastic Stable Intramedullary Nailing—A Safe and Effective Minimally Invasive Treatment

Background/Objectives: The radiological and clinical outcomes of elastic stable intramedullary nailing (ESIN) for pediatric humeral solitary bone cysts (SBCs) were assessed, with particular attention to healing, recurrence, complications, and functional recovery. Methods: This retrospective institutional study included 25 children with humeral solitary bone cysts treated with elastic stable intramedullary nailing between January 2019 and December 2025. Patients treated exclusively with ESIN and with a minimum follow-up of 12 months were included. Radiographic healing was assessed using the Capanna classification. Clinical outcomes included pain, range of motion, complications, refracture, and recurrence. Results: The cohort consisted of 16 boys (64%) and 9 girls (36%), with a median age of 11 years. Pathological fractures were present in 56% of cases. A total of 29 surgical procedures were performed, including growth-related implant exchanges in selected patients. Cyst dimensions decreased progressively during follow-up (p < 0.001). At final evaluation, 64% of lesions demonstrated complete healing (Capanna I), 28% incomplete healing (Capanna II), and 8% recurrence (Capanna III); no cases of non-response were observed. No recurrent fractures or postoperative complications occurred. Pain resolved within one month in all patients, and a full range of motion was restored. Conclusions: Elastic stable intramedullary nailing appears to provide reliable stabilization and promotes cyst healing in pediatric humeral SBCs, with low recurrence rates and excellent functional outcomes.