Congenital pseudoarthrosis of the tibia (CPT) is a rare disease characterised by the onset of bone anomalies or fractures, leading to deformities in paediatric patients. The aetiology of this pathology is unknown. The main theories include the presence of hamartomatous tissue related to Neurofibromatosis type 1, vascularisation deficit of the periosteum and alterations in the numbers and functions of the osteoblasts and osteoclasts in loco. Surgical treatment generally requires multiple operations during the patient's childhood and adolescence. The best outcomes seem to occur when using intramedullary nailing, vascularised fibular transplant and external fixation with the Ilizarov technique. The purpose of this paper is to evaluate the effectiveness of in-situ injections of Bone Marrow Aspirate Concentrate (BMAC) as an adjuvant therapy for congenital pseudoarthrosis of the tibia in patients treated with external fixation and that of radiographic healing over time compared to external fixation treatment alone. We performed a retrospective review of clinical and radiographic records of patients affected by CPT and treated in the Paediatric Orthopaedics and Traumatology Department of the Gaetano Pini Orthopaedic Institute with in-situ injections of bone marrow aspirate concentrate (BMAC) on the pseudoarthrosis site, in addition to pseudoarthrosis site excision and application of circular external fixator frame in compression (Group A). The time needed to reach the radiological consolidation of the resection site was recorded and compared to that needed for patients treated with only pseudoarthrosis site excision and application of circular external fixator frame in compression (Group B). There is a statistically relevant improvement of healing time in patients affected by congenital pseudoarthrosis of the tibia treated with external fixation and bone marrow aspirate concentrate compared to patients affected by the same pathology treated with external fixation only. Injection of MSC in the pseudoarthrosis site after focus removal in combination with circular external fixation achieves faster bone healing compared with external fixation only, and the lower refracture percentage may be associated with the better quality and structure of the new bone. However, it would be desirable to have a longer followup to determine if the results of the BMC as adjuvant therapy will hold up over time.