Hip flexion contracture caused by an intraspinal osteochondroma of the lumbar spine

Osteochondroma (or osteocartilaginous exostosis) is the most common bone tumor of childhood, with an incidence ranging from 1 to 1.4 per 1,000,000. In the lumbar spine, osteochondromata usually arise from the posterior column at the secondary ossification center and grow away from the spinal canal without causing neurologic deficits. This article reports a rare intraspinal lumbar osteochondroma that compressed the thecal sac, resulting in a hip flexion contracture in an 11-year-old boy. This lumbar, intraspinal, extradural exostosis was confluent with the L3 inferior articular process and compressed the L3 nerve root and thecal sac severely. The patient underwent an en bloc resection of the tumor with a right-sided hemilaminectomy of L3 and L4, a right-sided partial facetectomy at L3 to L4, and an extended resection from the pars intra-articularis of the L2 to the L5 vertebrae. The tumor specimen measured 4.8×3.7×2.5 cm with clear margins. Instrumented posterolateral fusion was completed from L2 to L5 due to iatrogenic instability from the resection. The patient had an uneventful recovery and returned to his normal activities of daily living, including sports. He remains asymptomatic at 54-month follow-up. A solitary lumbar osteochondroma that compresses the spinal cord, resulting in a motor neurological deficit, has not been reported in a pediatric patient. Orthopedic surgeons should be aware of potential intraspinal presentation of osteochondromas. Magnetic resonance imaging is the modality of choice in diagnosing and screening for spinal osteochondromas. These cases can be treated with resection surgery.