Early clinical and radiological outcomes of a scapular spine load-bearing strut in custom glenoid implants for reverse total shoulder arthroplasty

Background

Severe glenoid bone deficiency is a challenge in complex primary and revision shoulder arthroplasty, but lately, custom glenoid baseplates have demonstrated good outcomes. Lima Promade 3D-printed implants have recently utilized a strut to load share through the scapular spine to increase stability in patients with the most severe glenoid bone loss. We have assessed early clinical and radiological outcomes and reviewed complications.

Methods

This was a retrospective multisurgeon, single-center study, reviewing 19 patients with a minimum 2-year follow-up. Preoperative imaging was assessed for bone loss. Routinely performed postoperative computed tomography (CT) scans, radiographs, and Oxford Shoulder Scores were reviewed. CT scans were reported by independent musculoskeletal radiologists. Patient records were reviewed for any complications.

Results

19 patients with a mean age of 66 (42-89) and a mean follow-up of 3.6 years (2-8) were identified. 11 were revision procedures. 14/19 had severe bone loss (Seebauer-Gupta E4/C4) and 5 had severe dysplasia with >30° retroversion (Seebauer-Gupta E3/E4). 16/19 had a postoperative CT scan, with 14 showing good osseointegration; 1 reported partial osseointegration, and 1 suspected loosening but was asymptomatic. One patient had a magnetic resonance imaging scan with no suspicion of loosening. Pre and postoperative Oxford Shoulder Scores were available in 13 patients and improved from a mean of 14/48 preoperatively to 32/48 postoperatively. Complications were reported in 5 patients (26%), with 1 humeral component revision, 2 with limited external rotation, 1 acromial stress fracture, and 1 keloid scarring. No glenoid baseplates required revision.

Discussion

This is the first case series to report on the use of a scapular spine strut as part of a custom glenoid baseplate construct. Early outcomes report good osseointegration and good improvements in patient-reported outcome measures. The complication rate in our series was within the range described in the literature for complex shoulder replacement, and we report 100% implant survival at a minimum of 2 years. Early outcomes would suggest this is a safe technique to balance shear forces and improve stability in patients with severe glenoid bone loss and does not appear to increase the risk of acromial stress fractures beyond that reported in the literature. Further study is on-going to assess the medium- and long-term outcomes in these patients.