Shoulder Arthroplasty for Humeral Head Avascular Necrosis Is Associated With Increased Postoperative Complications.

Background: Humeral head avascular necrosis (AVN) of differing etiologies may lead to shoulder arthroplasty due to subchondral bone collapse and deformity of the articular surface. There have been no large studies evaluating the complications for these patients after they undergo total shoulder arthroplasty (TSA). Questions/Purposes: The first objective of this study is to evaluate the complication rate after TSA in patients with humeral head AVN. The secondary objective is to compare the complication rates among the different etiologies of the AVN.
Methods: Patients who underwent TSA were identified in the PearlDiver database using ICD-9 codes. Patients who underwent shoulder arthroplasty for humeral head AVN were identified using ICD-9 codes and were subclassified according to AVN etiology (posttraumatic, alcohol use, chronic steroid use, and idiopathic). Complications evaluated included postoperative infection within 6 months, dislocation within 1 year, revision shoulder arthroplasty up to 8 years postoperatively, shoulder stiffness within 1 year, and periprosthetic fracture within 1 year and systemic complications within 3 months. Postoperative complication rates were compared to controls.
Results: The study cohorts included 4129 TSA patients with AVN with 141,778 control TSA patients. Patients with posttraumatic AVN were significantly more likely to have a postoperative infection (OR 2.47, P < 0.001), dislocation (OR 1.45, P = 0.029), revision surgery (OR 1.53, P = 0.001), stiffness (OR 1.24, P = 0.042), and systemic complication (OR 1.49, P < 0.001). Steroid-associated AVN was associated with a significantly increased risk for a postoperative infection (OR 1.72, P = 0.004), revision surgery (OR 1.33, P = 0.040), fracture (OR 2.76, P = 0.002), and systemic complication (OR 1.59, P < 0.001). Idiopathic and alcohol-associated AVN were not significantly associated with any of the postoperative evaluated complications. Conclusions: TSA in patients with humeral head AVN is associated with significantly increased rates of numerous postoperative complications compared to patients without a diagnosis of AVN, including infection, dislocation, revision arthroplasty, stiffness, periprosthetic fracture, and medical complications. Specifically, AVN due to steroid use or from a posttraumatic cause appears to be associated with the statistically highest rates of postoperative TSA complications. Given these findings, orthopedic surgeons should be increasingly aware of this association, which should influence the shared decision-making process of undergoing TSA in patients with humeral head AVN.