Convertible glenoid replacement in the anatomical total shoulder arthroplasty: medium-term results

Area of Science:

• Orthopedic Surgery
• Biomaterials Engineering
• Radiology

Background:

• Older metal-backed glenoid prostheses exhibited high failure rates due to their thickness.
• A technically modified generation of metal-backed glenoids with a 35% reduction in thickness was developed.
• This study aimed to evaluate the medium-term clinical and radiological outcomes of these thinner glenoid components.

Purpose of the Study:

• To assess the clinical efficacy and radiological performance of a novel, thinner metal-backed glenoid prosthesis.
• To compare the outcomes of this modified prosthesis against historical data of thicker components.
• To identify factors influencing functional results and complication rates.

Main Methods:

• A cohort of 39 patients (43 shoulders) with a mean age of 66.5 years were followed for 2-10 years (mean 71.2 months).
• Clinical evaluation included the Constant-Score and Subjective Shoulder Value (PROM).
• Radiological assessment utilized anteroposterior and axial X-rays to evaluate glenoid protrusion, radiolucent lines, osteolysis, and humeral/glenoid positioning.

Main Results:

• Significant improvement in the absolute Constant Score (CS) from 43 to 80 points post-surgery (p < 0.0001).
• Preoperative glenoid protrusion (Walch classification) was the only negative predictor of outcome (p = 0.0150).
• Complication rates (11.7%) and revision rates were lower than with conventional thicker metal-backed glenoids, with successful conversions to reverse prostheses when necessary.

Conclusions:

• Thinner metal-backed glenoid components achieve favorable medium-term clinical results, particularly in patients with eccentric glenoid types.
• Severe preoperative glenoid erosion did not negatively impact postoperative functional outcomes.
• The modified glenoid components demonstrate improved safety profiles compared to previous generations, with successful revision options available.