Anatomy of flexor pollicis longus vinculum system

Area of Science:

• Anatomy
• Orthopedic Surgery
• Biomechanics

Background:

• The flexor pollicis longus tendon is crucial for thumb flexion.
• Tendon injuries can significantly impair hand function.
• The role of the vinculum breve in maintaining function after injury is not fully understood.

Purpose of the Study:

• To investigate the anatomical prevalence and functional significance of the flexor pollicis longus vinculum breve.
• To determine if the vinculum breve can transmit flexion force after tendon laceration.
• To identify clinical tests to differentiate intact tendons from those with vinculum breve support.

Main Methods:

• Anatomical study of 90% of thumbs to determine vinculum breve prevalence.
• Functional assessment of tendon excursion with an intact vinculum breve after simulated laceration.
• Development and testing of an opposed resistance flexion test.

Main Results:

• The vinculum breve was present in approximately 90% of the studied thumbs.
• An intact vinculum breve can transmit flexion force to the interphalangeal joint after flexor pollicis longus tendon laceration.
• The opposed resistance flexion test can differentiate an intact flexor pollicis longus from a lacerated tendon supported only by the vinculum breve.
• A lacerated flexor pollicis longus tendon can exhibit a maximum excursion of 24.5 +/- 8 mm while the vinculum breve remains intact.

Conclusions:

• The flexor pollicis longus vinculum breve is a significant anatomical structure with a high prevalence.
• This structure plays a vital role in maintaining thumb flexion capabilities even after tendon laceration.
• Clinical examination including the opposed resistance flexion test is valuable for assessing flexor pollicis longus tendon integrity.