Preliminary Results of a Novel Hybrid Cage Glenoid Compared to an All-Polyethylene Glenoid in Total Shoulder Arthroplasty. 

Abstract

INTRODUCTION:

The aim of this study was to evaluate the preliminary outcomes of a hybrid cage glenoid design in comparison to pegged all-polyethylene glenoid components in anatomic total shoulder arthroplasty (aTSA). 

MATERIALS AND METHODS:

Ninety-two patients undergoing primary anatomic total shoulder arthroplasty with minimum two-year follow-up were reviewed.  Forty-six patients had an ultra-high molecular weight polyethylene (UHMWPE) cemented pegged glenoid component, and 46 had a hybrid cage glenoid component.  Patient data was retrospectively reviewed from prospectively acquired data in a multi-institutional IRB approved database.  These age, gender, and follow-up matched patients were evaluated and scored preoperatively and a latest follow-up using the SST, UCLA, ASES, Constant, and SPADI scoring metrics.  Additional measures included active abduction, elevation, and external rotation.  Radiolucent line assessment of the glenoid was performed by use of a Grashey and axillary radiograph at latest follow-up.  A Student's two tailed, unpaired t-test was used to identify differences in preoperative and postoperative results, where p < 0.05 denoted a significant difference. 

RESULTS:

All patients demonstrated significant improvements in pain and function following treatment with the primary aTSA.  The database contained three complications for the aTSA patients with a cage glenoid, and three complications for patients with a UHMWPE pegged glenoid.  Radiographic data was available for 37 of 46 cage glenoid patients and 29 of 46 UHMWPE pegged glenoid patients.  Five of 37 cage glenoid patients had a radiolucent line (13.5%) with an average radiographic line score of 0.22.  Eight of 29 UHMWPE peg glenoid patients had a radiolucent line (27.6%) with an average radiographic line score of 0.57.  Cage aTSA patients were associated with significantly less blood loss than aTSA UHMWPE pegged glenoid patients (avg.  blood loss = 242 vs. 337; p = 0.022). 

CONCLUSION:

At minimum two-year follow-up, hybrid cage aTSA components show equal clinical outcomes to UHMWPE pegged glenoids.  However, the hybrid cage components had significantly fewer radiolucent lines and less intra-operative blood loss.  Additional and longer-term clinical and radiographic follow-up is necessary to confirm these promising early results.