Heterotopic Ossification following Reverse Total Shoulder Arthroplasty

Background: Heterotopic Ossification (HO) is a well-known complication following arthroplasty procedures, most commonly of the hip. As the reverse total shoulder arthroplasty (RTS) system becomes more popular, the incidence and clinical consequences of HO such as pain and decreased range of motion remains unclear. The few studies reporting HO after RTS have observed variable rates. Our purpose was to (1) compare rate of incidence of HO after RTS in our population to the literature and (2) establish if common features exist between these patients. Understanding the risk factors for the formation of HO following RTS may decrease incidence and improve patients’ function and satisfaction.

Methods: A retrospective evaluation of patients who underwent primary RTS in our institute between 2015-2016 using the DELTA XTEND (J&J). Demographics and clinical encounters were collected and x-ray imaging of 40 patients were graded according to the NEER proximal humerus fracture classification. Average age was 73 years, 82% were female, and 55% left-handed. Average cohort follow up was 23 weeks post-operatively, and average follow up from first radiographic evidence of HO was 4 weeks.

Results: Of 40 patients who underwent RTS arthroplasty, 7 (17.5%) developed HO. According to NEER proximal humerus fracture classification, 18 (45%) had 4 part proximal humers fracture/fracture dislocation, 15 (37%) had 3 part proximal humerus fracture/fracture dislocation and 7 (17%) had degenerative changes due to cuff arthropathy. 1/7 (14%) patients who developed HO, underwent reoperation due to pain and decreased range of motion. 6/7 (85%)patients who developed HO were under the category of 4 part fracture/fracture dislocation. Overall 33% of the 4 part proximal humerus fracture group developed HO.

Conclusion: Our results show a correlation between HO and RTS arthroplasty in patients with 4 part proximal humerus fracture/fracture dislocation according to NEER classification.