GLENOID COMPONENT LOOSENING IN TOTAL SHOULDER ARTHROPLASTY: INTEREST OF A NEW METAL-BACKED COMPONENT DEVOTED TO REVISION SURGERY

Abstract

Glenoid component loosening is a concern in long term outcome of total shoulder arthroplasty. Unfortunately revision of glenoid loosening remains very challenging regarding bone reconstruction and reimplantation of a glenoid component. A new design metal-back component (Arrow™) seems to get the procedure easier and lead to higly best clinical and radiological results than prior technics.

It is a retrospective study of 34 patients operated on for isolated aseptic glenoid component loosening between 1997 and 2007. Glenoid bone loss based on a new classification was rated in 5 degrees. All patients were reviewed at a mean follow up of 34 months (from 12 to 89). Pre and post operatively Constant score and SST have been evaluated. Fluoroscopic views and CT scan have been performed for radiologic assesment.

Mean delay for revision surgery was 58 months (from 28 to 134 months). 16 patients underwent only bone graft reconstruction. 18 patients underwent both bone reconstruction and glenoid implant reimplantation.

Autolog bone graft (iliac crest) was used in 19 cases, allograft bone in 5 cases, and both autolog and dried bone substitutes in 10 cases. The glenoid component was an uncemented metal-backed in 11 cases, and a polyethylene cemented in 2 cases. The new metal-backed bone ingrowth component is composed with a keel and a winglet securing bone graft fixation and implant stability. For the all cohort Constant score improves of 21 points (from 35 to 56). Gain of pain and active motion is statiscally significative (p< 0.005).Patients who underwent reimplantation of a new glenoid component had a higher clinical result (Constant score: 66) than those who underwent only a bone graft reconstruction (Constant score: 52) in term of pain and active forward elevation as well (p< 0.001). At maximum follow up (32 months) no radiolucent lines or loosening of the new glenoid component was noted. Patients who underwent only bone reconstruction showed a mild glenoid erosion due to subsidence and resorption of cancellous auto or allograft bone.

Revision of glenoid component depends on the glenoid bone stock specially about posterior defect. The use of cortical autolog bone graft and new metalback component allows better glenoid reconstruction, secure the stabiliy of the new gle and yields to goods clinical results restoring painless shoulder and function. Reimplantation of a glenoid component becomes an adequate procedure for total shoulder arthroplasty revision