Among all skeletal tumors, osteochondroma constitutes about 10-15 % ^[1] Non-traumatic fracture of osteochondroma through the stalk is a known, but rare complication.Treatment protocols for such complication are debatable. However, surgical intervene have been advocated ^[2]. It is going to be case reported as a perusal of rare entity.

A 14 years old male patient presented to our outpatient department with pain, redness, and swelling over distal and posterolateral aspect of left thigh with 4 days. On history, taking patient stated that he had a gradual progressive painless mild swelling over that area for 6 month. For 4 days patient increased pain, redness, along with increments in size of previous. He did not reveal episode of recent significant trauma. On physical examination, there was tender, palpable mild swelling over posterolateral aspect of distal thigh. Hip joint was normal but knee joint was painful and restricted due to pain. Distal neurovascular status was intact. Past medical history was insignificant. On radiographic examination, it showed fracture through base of pedunculated osteochondroma, which was situated in distal left thigh postreolaterally (fig-1). On meticulous questioning patient gave the history of mild intermittent pain over osteochondroma site after moderate to severe exertion. For excision posterolatearl approach used, vastus lateralis reflected anteriorly and plane developed between it and lateral intermuscular septum covering hastring muscles ( internervous plane of femoral and sciatic nerve) and extraperiosteally reached to the base of growth. With the help of chisel, extra-periosteal excision done (with cartilaginous cap) and raw surface filed,(fig-2) and confirmation was done after histopathological examination. Recuperating period was uneventful and patient resume to previous activity status after two week.

Most common presenting age of osteochondroma is childhood or in the second decade ^[3]. Most of the time it is symptomless, and beings diagnosed incidentally ^[4]. Fracture, bursa formation, malignant transition and neurovascular compromise are mentioned complications of osteochondroma which entail it for being symptomatic ^[5,6]. Malignant transition in solitary lesion of osteochondroma is very less (1%) in comparison to autosomal dominant hereditary multiple exostoses, in which it may be up to 5% ^[1,8,9,10].Usually pathognonomonic radiological features are sufficient for delineating it, and CT scan is further needed for diagnostic confirmation and pre-op management. MRI is preferable diagnostic tool to detect malignant change. It also measures the cartilaginous cap, which (≥ 1.5cm) may be the herald of malignant changes ^[1,2,11]. Biopsy usually not used, until other diagnostic tools fail, due to chance of spreading.
Commonest site of fracture of osteochondroma is around knee ^[1,2,12,13].In little number of cases, non-traumatic fracture of pedunculated osteochondroma has been reported ^{[4,7,13,16,17]}. Fracture of osteochondroma may occur due to direct or indirect injury. Growth of stalked osteochondroma leads to weakness at its stalk, so the violent muscle contraction or relative frictions of muscle may cause the fracture and pain in the absence of history of trauma ^[14,15].Carpintero et al. noticed fracture of osteochondroma occurred due to indirect violent muscle contraction ^[2]. Our patient did not give the history of significant trauma so it was the probable cause of fracture. Observation and conservative management has also been suggested for such a rare complication, but surgery gives quicker recovery and return to normalcy ^[2,7]. In our case report, it was also true in which patient got full recovery in two week.

In conclusion, it was an uncommon type of presentation of non-traumatic fracture of pedunculated osteochondroma. By pathology and clinico-radiological examination, it was a benign diagnosis. We also recommend operative intervention for this rare complication.