Functional Composite Spacer (Antibiotic Cement around a Hemiarthroplasty) for the Treatment of Shoulder Infections: Minimum 5-Year Outcomes.

Background: Periprosthetic infections remain a challenging complication following shoulder arthroplasty and an ideal treatment protocol has yet to be established. Two-stage revision is a common approach. Historically, the first stage entails placement of an all-cement antibiotic spacer. While prior studies have reported on cement spacers as definitive management, persistent pain and inadequate function often lead many to later request a second stage procedure. The functional composite spacer consists of a humeral hemiarthroplasty implant with antibiotic cement coated around the stem alone to preserve the metallic humeral head-glenoid articulation. Functional composite spacers have demonstrated improvements in function and motion with high patient satisfaction at 25 months, but longer-term follow-up is needed to better understand the role it may play in the management of shoulder infections. The purpose of this study is to evaluate outcomes at a minimum of 5 years in patients who initially planned to undergo two-stage revision but elected to retain the functional spacer.

Methods: A retrospective review of a single institution's shoulder surgery repository from 2007 to 2018 identified 30 patients who underwent placement of a composite spacer. Overall, 5 patients underwent second stage reimplantation and 12 patients did not have 5-year follow-up (6 lost to follow-up and 6 deceased). A total 13 patients were included who maintained a functional composite spacer and had minimum 5-year follow-up. Patient-reported outcome measures (ASES, SST, SANE, VAS F and VAS P), satisfaction, range of motion, and radiographic estimation of glenoid wear were evaluated.

Results: Two of 13 patients (15%) required additional surgery: one secondary closure for early superficial wound dehiscence and one revision spacer for pain. There were no re-infections. At most recent follow-up patient satisfaction was high and significant improvements were noted for ASES (45.4; p<0.001), SST (5.3; p=0.003), SANE (47.3; p=0.002), VAS F (4.9; p=0.004), and VAS P (-4.4; p=0.007) as well as range of motion including abduction (39.2˚; p=0.005) and elevation (65.9˚; p=0.005). There was no significant change in humeral head medialization (p=0.11).

Conclusions: Patients who do not undergo an early revision and retain a functional composite spacer maintain good function and range of motion with minimal pain at mid-term follow-up.