Anatomy of the flexor retinaculum

Area of Science:

• Anatomy
• Orthopedics
• Surgical Anatomy

Background:

• Carpal tunnel syndrome is a common condition.
• Accurate anatomic definition of the carpal tunnel is crucial for surgical interventions.
• Current surgical approaches may not fully address the entire flexor retinaculum.

Purpose of the Study:

• To accurately define the anatomic limits and dimensions of the carpal tunnel.
• To provide an anatomic basis for optimizing surgical release procedures for carpal tunnel syndrome.

Main Methods:

• Gross dissection of 10 cadaver upper extremities.
• Histologic examination of 3 cadaver upper extremities.
• Radiographic analysis of 13 cadaver upper extremities.

Main Results:

• The flexor retinaculum extends from the distal radius to the base of the third metacarpal.
• Mean proximal limit of the central flexor retinaculum is 11 mm distal to the capitate-lunate joint.
• Mean distal limit of the distal flexor retinaculum is 10 mm distal to the third carpometacarpal joint.
• Carpal tunnel width at the hamate hook (20 mm) is narrower than proximal (24 mm) and distal (25 mm) extents.
• The palmar boundary includes proximal fascia, transverse carpal ligament, and distal aponeurosis.

Conclusions:

• The palmar boundary of the carpal tunnel is composed of three continuous segments.
• This redefined anatomy provides a rationale for more comprehensive surgical release in carpal tunnel syndrome treatment.