Purpose: Many surgical techniques have been described for the treatment of pathological fractures due to aggressive unicameral bone cysts in order to varying rates of success and incomplete healing or recurrence. Many Authors suggested curettage and bone grafting as effective treatment in case of active lesion in children 8 – 12 years old, adjacent to the physis with width of the lesion exceeds that of the adjacent physis and recurrence or persistence. Due to invasive nature of operation this method non is preferred by several Authors : we preferred minimally invasive treatment consisting closed reduction and flexible with titanium rod (Nancy)intramedullary fixation for low operative morbidity whether for the fracture or for the cyst; in case of recurrence of the cyst the closed curettage of the cyst with arthroscopic technique can be applied successful.

Methods: Between 2002–2004 40 aggressive unicameral cysts were observed as pathologic fractures in patients between 5–15 years old in these cases there was a significant loss of bone stock. The site of involvement was in 33 patients the metadiaphysis of humerus, in 7 the femur; radiograms reveal expanding lesion in metaphyseal-diaphyseal site with cortex tinned from its inner surface and erosion with infraction with displacement. The parents were informed about contextual presence of two lesions: the fracture and cyst. The proposed internal fixation with Nancy titanium rods heals the first and might heal the second lesion ; in case of failure this method do not exclude another possibility of treatment as arthroscopic curettage. The Nancy flexible intramedullary fixation was performed with retrograde access 3 0 4 mm. diameter. Two nails with “ Eiffel Tower” construction were inserted by two miniportals 1 centimetres far from the physis. Follow up of treated lesion was made with periodic x rays performed every 45 days.

Results: In 36 patients after a 2-year period of observation the cyst has completely or incompletely healed but with a sufficient bone stock in the remainder four cases the arthroscopic procedure was performed. Curettage of cystic wall by trimmer blade and multiple miniportals 4,5 millimetres is the best way to treat all the cyst. In all the cases we used the standard optical cannula 30°.

Conclusions: In conclusion minimally invasive treatment by Nancy rods and artrhoscopy can be effective because assure high incidence of favourable results by decompression-scaffolding of the lesions, the patient quickly recover natural life and school attendance.