The anatomy of the scaphoid

Area of Science:

• Orthopedics
• Biomechanics
• Anatomy

Background:

• The scaphoid bone is crucial for carpal joint function, connecting proximal and distal rows.
• Its unique geometry influences wrist kinematics, particularly under longitudinal loading.
• The scaphoid's structure predisposes it to injury during extreme wrist movements.

Purpose of the Study:

• To elucidate the biomechanical factors contributing to scaphoid fractures.
• To understand the mechanism of injury related to wrist extension and loading.
• To identify factors leading to proximal scaphoid fracture displacement and ischemia.

Main Methods:

• Analysis of scaphoid bone anatomy and its role in carpal kinematics.
• Review of biomechanical principles governing wrist joint mechanics.
• Examination of fracture patterns and vascular supply related to scaphoid injuries.

Main Results:

• The scaphoid's offset articular surfaces promote palmar-flexion under load.
• Wrist extension increases tension on the palmar cortex, predisposing to fracture.
• Fractures proximal to the waist are prone to displacement and avascular complications due to vascular patterns.

Conclusions:

• Excessive wrist extension, ulnar deviation, and loading are key risk factors for scaphoid fractures.
• Proximal scaphoid fractures carry a high risk of displacement and compromised blood supply.
• Understanding these biomechanical factors is vital for preventing and managing scaphoid injuries.