Heterotopic ossification after total shoulder arthroplasty.

Fifty-eight primary ingrowth total shoulder arthroplasties, performed between 1989 and 1992, with a minimum of 2 years' radiographic and clinical follow-up (mean, 4.7 years), were reviewed to determine the frequency and clinical significance of heterotopic ossification after total shoulder arthroplasty. Fourteen of the 58 shoulders had radiographic evidence of heterotopic ossification: grade I (12 shoulders) and grade II (2 shoulders). Heterotopic ossification was present on the early postoperative radiographs (1-2 months) in 12 of the 14 shoulders. Among these 12 shoulders, there was no increase in the grade of ossification comparing the early postoperative radiographs with those obtained at a minimum of 2 years. There were no identifiable preoperative patient characteristics associated with the development of heterotopic ossification (P > .05). Range of motion, pain, and result rating were not statistically different comparing patients with and without heterotopic ossification (P > .05). The data from this study suggest that when heterotopic ossification develops after elective total shoulder arthroplasty, it is usually low grade, is present in the early postoperative period, is nonprogressive, and does not adversely affect the clinical results.