The presence of multiple osteochondromas does not necessarily require resection. Removal of symptomatic or symptom-causing osteochondromas should be considered only if local pain occurs or if pressure symptoms develop. The procedure is the same as for isolated osteochondromas. The osteochondroma must be removed along with the periosteum that covers it, otherwise it is likely to recur. In case of malignant transformation into chondrosarcoma, microwave antenna inactivation with in situ tumor separation can be used, and bone defects can be reconstructed with allograft bone. Malignant changes in the pelvis are more difficult to deal with, and the recurrence rate is very high because it is not easy to remove completely. Radiation therapy is not effective for chondrosarcoma. For more severe bone deformities, osteotomy or osteotomy or end resection can be performed when the patient is an adult. Radial head or ulnar head resection can be performed in cases of combined brachioradial or inferior ulnar radial dislocation with significant limitation of forearm rotation. If the ulnar deviation of the affected hand is obvious, osteotomy of the lower radius is feasible, and if the tibia is obviously exostosis, osteotomy of the proximal tibia is feasible.