Premorbid retroversion is significantly greater in type B2 glenoids

Area of Science:

• Orthopedic surgery
• Anatomy
• Biomechanical engineering

Background:

• Posterior glenoid erosion is linked to humeral head subluxation.
• The role of osseous morphology versus soft-tissue factors in subluxation and erosion is unclear.
• This study investigates premorbid glenoid morphology as a potential contributor.

Purpose of the Study:

• To test the hypothesis that patients with posterior glenoid erosion have inherently retroverted and inferiorly inclined glenoids.
• To compare premorbid glenoid morphology in osteoarthritic (Type B2) and normal glenoids.

Main Methods:

• Examined 80 scapulae (40 osteoarthritic Type B2, 40 age-matched normal).
• Utilized 3D computed tomography reconstructions to measure glenoid version and inclination.
• Focused measurements on the anterior paleoglenoid region, considered representative of the premorbid state.

Main Results:

• Type B2 glenoids exhibited significantly greater retroversion (-14° ± 6°) compared to normal glenoids (-5° ± 5°) (P < .001).
• No significant difference in glenoid inclination angle was found between Type B2 (0° ± 6°) and normal glenoids (2° ± 5°) (P = .166).
• Negative values indicate retroverted and inferiorly inclined glenoids.

Conclusions:

• Patients with Type B2 osteoarthritic glenoids demonstrate significantly increased premorbid glenoid retroversion.
• This premorbid morphologic variation may be a contributing factor to posterior glenoid erosion.
• Understanding these variations offers insight into the pathoanatomy of humeral head subluxation and osteoarthritis.