Covariations between scapular shape and bone density in B-glenoids: A statistical shape and density modeling-approach

Area of Science:

• Orthopedic surgery
• Biomedical engineering
• Radiology

Background:

• B-type glenoids feature posterior humeral head migration and erosion, leading to retroversion.
• This morphology increases the risk of glenoid component loosening after anatomic total shoulder arthroplasty (aTSA).
• Surgical planning for B-type glenoids requires balancing bony shape correction with bone support quality.

Purpose of the Study:

• To systematically quantify scapular morphology and bone mineral density variations in B-type glenoids.
• To identify covariation patterns between scapular shape and bone density in these patients.
• To inform surgical strategies for improving outcomes in aTSA for B-type glenoids.

Main Methods:

• Constructed 3D scapular surface models from CT scans of 62 patients.
• Developed statistical shape models (SSM) and statistical density models (SDM) using surface and volumetric registration.
• Employed partial least square correlation (PLSC) to analyze covariation between morphology and density.

Main Results:

• SSM and SDM captured 85.9% and 56.6% of variability, respectively.
• Four modes of covariation were identified, explaining 66.0% of the correlation.
• The primary covariation involved posterior-inferior erosion, posterior sclerotic bone, and reduced anterior/central bone density.

Conclusions:

• Asymmetrical bone density distribution in B-type glenoids is linked to glenoid component loosening.
• Findings provide insights for surgical guidelines to optimize bone support during aTSA.
• This research aids in balancing bony correction with structural integrity for B-type glenoids.