Complicated Fracture and Resorption of an Osteochondroma

Aims: To describe two unusual complications of a typical solitary pedunculated femoral osteochondroma that included a distal fracture of the exostosis and a missed fragment following surgical treatment as well as to evaluate the progress of the untreated free fragment at follow-up.
Case Presentation: A 13-year-old boy consulted for a painful bruising of the medial side of the right knee following injury. Radiological survey indicated a pedunculated osteochondroma of the distal femoral metaphysis but there was no evidence of a fracture line. Surgical removal of the lesion was uncomplicated but the post-operative radiographs indicated an osteocartilaginous portion of the osteochondroma missed in the thigh musculature. No further surgical intervention was undertaken. Radiographic follow-up revealed gradual regression and complete resorption of the free fragment 3 years later. No complications have been recorded at the most recent follow-up, 10 years later.
Discussion: Fracture through the base or stalk of a pedunculated osteochondroma is a rare complication but the diagnosis of a distally fractured exostosis has not been previously reported. Regression or resorption of a solitary pedunculated osteochondroma following a fracture is also very rare. Although recurrence of the lesion in the reported patient would be very likely, complete resorption was evident instead within 3 years.
Conclusion: An obscure distal fracture of a penduculated osteochondroma may be suspected in cases that a clinical diagnosis of a fractured exostosis is not associated with the radiographic detection of a fracture line through its stalk. Radiographic control during surgery is necessary to ensure complete removal in cases with a clinically, or even radiologically, diagnosed fractured exostosis. Surgical excision of a distally fractured osteochondroma may be avoided, since complete resorption of the distal fragment may be evident in a few years.