Hereditary multiple osteochondromas (HME), also known as multiple exophytic warts and diaphyseal sequelae, are characterized by disorders of osteogenesis within the cartilage, manifested by abnormal protrusion of the epiphysis with cartilage cap, defective epiphyseal shaping, blocked bone growth, and secondary deformities such as limb asymmetry. It is an autosomal dominant disorder with a family history in 65-90% of cases. The lesions are not easily detected during infancy and early childhood. As children grow and develop, the lesions increase in size, with secondary deformities, asymmetric growth and functional impairment. After bone development matures, the growth of the lesion slows or stops. The forearm and wrist are the most common sites of lesions. The masses tend to grow on the distal ulna and distal radius. HME not only has a high incidence in the forearm, but also has the greatest functional impact. It is often associated with limited movement of the elbow, wrist, and forearm, pain, and early osteoarthritic manifestations.
Treatment of HME forearm deformity is aimed at improving appearance and function and preventing dislocation of the radial head. Commonly used clinical surgical methods include ulnar lengthening, swelling removal, distal radial osteotomy and hemiepiphyseal block. Early diagnosis, close observation and timely treatment are the basic principles in the current management of such disorders. Once the best time for surgery is lost, progressive aggravation of deformity and dysfunction can adversely affect the child’s future quality of life and ability to work. Although surgical orthopedics can temporarily improve the appearance, the deformity is prone to recurrence after surgery, so the child needs to be able to follow up for long-term review.
The malignancy rate of HME has been reported to be 1-2%. Although the majority of lesions in childhood are benign, the chance of malignancy increases with age. If the swelling increases rapidly and becomes painful, be on high alert for the possibility of malignant transformation into chondrosarcoma. This requires x-rays and MRI to determine if there are signs of tumor progression or malignancy.