Massive Heterotopic Ossification in the Subdeltoid Space after Shoulder Surgery and Symptomatic Improvement from Conservative Treatment: A Case Report

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Background: We herein report a case of heterotopic ossification (HO) in the subdeltoid space after open resection and rotator cuff repair in a patient with refractory calcific tendinitis. Case: A 56-year-old man was admitted to our hospital because of right shoulder pain and difficulty in raising his arm. The patient was diagnosed with calcific tendinitis with contracture of the right shoulder joint and was scheduled for surgery because of refractory shoulder pain. Calcium removal was performed using a mini-open approach. Postoperative radiographs showed no calcium deposits. There was mild residual pain at 3 months postoperatively, and the range of motion (ROM) had deteriorated when compared to preoperative levels. A massive ossified shadow was observed in the subdeltoid space on radiographs. Etidronate disodium was orally administered, and the patient continued to undergo careful rehabilitation. HO occurred at 3 months postoperatively, matured at 1 year postoperatively, and showed no progression between 1 year and 2 years postoperatively. The clinical symptoms corresponded with the image findings, and restricted ROM and decreased shoulder function scores were observed at 3 months postoperatively. Although the ROM remained restricted and the function score remained low until 1 year postoperatively, a gradual recovery was achieved at 2 years postoperatively, and the patient did not require reoperation. Discussion: Although early diagnosis, evaluation, and resection are recommended for treating HO, the maturation of bone may lead to symptomatic improvement and the prevention of reoperation, provided that careful rehabilitative measures are performed to avoid ankyloses.