Trabecular bone density distribution in the scapula relevant to reverse shoulder arthroplasty

Area of Science:

• Orthopedic surgery
• Biomechanical engineering
• Anatomy

Background:

• Trabecular bone density variations within the scapula are not well-documented.
• Understanding these variations is key to improving screw placement in reverse shoulder arthroplasty (RSA).
• The scapula's three trabecular bone columns (lateral border, coracoid process, spine) were hypothesized to have similar densities.

Purpose of the Study:

• To investigate the distribution of trabecular bone density within the scapula.
• To determine if specific regions of the scapula offer superior bone quality for implant fixation.
• To provide anatomical data for optimizing glenoid baseplate screw placement in RSA.

Main Methods:

• Computed tomography (CT) scans of 19 cadaver scapulae were analyzed.
• 3D digital models were generated using Mimics software.
• Trabecular bone density (Hounsfield units) was measured after excluding cortical bone.

Main Results:

• The coracoid process demonstrated statistically significant lower bone density compared to the scapular spine and lateral border.
• Significant differences in bone density were observed between these regions (P < .05).

Conclusions:

• The scapular spine and lateral border offer higher quality bone than the coracoid process.
• This suggests that screws placed in the spine and lateral border may achieve better bone purchase for glenoid baseplate fixation in RSA.
• Findings can guide surgical planning for improved RSA outcomes.