PAPER 167: FACTORS AFFECTING SURVIVORSHIP OF THE HUMERAL COMPONENT IN SHOULDER ARTHROPLASTY

Abstract

Purpose: Loosening of the humeral component is rarely a cause for revision shoulder surgery. Most long-term series are not large enough to stratify the many risk factors that might influence the survivorship of humeral component designs. The purpose of this study was to determine long-term survivorship of the Neer and Cofield humeral components and to define the risk factors associated with humeral component removal or revision.

Method: 1584 primary Neer and Cofield shoulder arthroplasties (1423 patients) were performed at our institution from 1984 to 2004. There were 619 men (694 shoulders) and 804 women (890 shoulders), with a mean age at arthroplasty of 65.6 years (range, 16–94 years). Kaplan-Meier survivorship analysis was used to determine the effect of etiology of the disease, gender, age, surgery type (hemi versus total), fixation type (cemented versus noncemented), and the humeral component type (Neer II, Cofield I or II) on the estimated survival free of humeral component revision or removal.

Results: There were 108 revisions and 17 removals of the humeral component. The overall rate of removal or revision of the humeral component was 7.9% with an average followup of 8.1 years. The rates of survivorship free of revision or removal of the humeral component for any reason was 94.8% at 5 years, 92% at 10 years, 86.7% at 15 years and 82.8% at 20 years. Seventy-one of 632 shoulders (11.2%) in patients younger than 65 years required humeral component revision or removal, whereas only 54 of 952 shoulders (5.7%) in patients 65 years and older required humeral component revision or removal (Odds ratio=2.1; 95% confidence interval, 1.5–3, p=0.001). Patients with posttraumatic arthritis had a higher risk of needing revision or removal of the humeral component (Odds ratio=2.1, 95% confidence interval 1.3–3.3) compared to osteoarthritis. Eighty-four of 526 shoulders (16.0%) with metal-back glenoid components required humeral component revision or removal, whereas only 41 of 1058 shoulders (3.9%) with non metal-backed glenoid components required humeral component revision or removal (Odds ratio=4.7; 95% confidence interval, 3.2–7, p=0.001).

Conclusion: Younger age, replacement due to post-traumatic arthritis and presence of a metal-backed glenoid increased the likelihood of humeral component failure. Similar short-term survival can be achieved with Cofield II and Neer II humeral components.