Massive ossification around the prosthesis after limb salvage treatment for osteosarcoma

Abstract

Heterotopic ossification (HO) is a condition defined by the formation of mature lamellar bone with bone marrow in soft tissues, mainly occurring around major joints. HO may be caused by either neurogenic or traumatic processes, including operative procedures, and often both may be involved simultaneously. Postoperative development of HO is a common and sometimes disabling problem in patients who receive prosthesis-based treatment in the extremities, such as total hip arthroplasty (THA). In general, HO becomes apparent on radiographs 3 or 4 weeks after THA, with progression to mature lamellar bone in 3–6 months [1]. The incidence of HO after THA varies, ranging from 0.6 to 90%, although an average incidence of approximately 53% after THA has been reported [2–4]. Often, the HO that develops after THA is minor and not clinically significant. We report a rare case of a patient who developed massive HO around the prosthesis after limbsalvage treatment for osteosarcoma, which should be distinguished from local recurrence of osteosarcoma and might be a reason for prosthesis stability. We followed up this patient for approximately 7 years and observed no suspicious malignant features in either clinical or imaging tests. During the follow-up, the patient underwent partial lung resections because of lung metastasis in the sixth and seventh years after the wide resection and reconstruction surgery, and remains alive with no disease at the time of writing this report.