Which palmar (volar) ligaments of the wrist are most commonly sprained in a fall on an outstretched hand (FOOSH)?

Volar Wrist Ligaments Commonly Injured in FOOSH

The palmar (volar) radiocarpal ligaments—specifically the radioscaphocapitate, radiolunate, and ulnolunate ligaments—are the primary volar ligaments injured in FOOSH injuries, with these structures experiencing tension failure as the wrist hyperextends during impact.

Primary Volar Ligaments at Risk

The volar ligamentous complex forms a critical stabilizing "belt" on the palmar aspect of the wrist. In FOOSH injuries, the mechanism involves forced wrist hyperextension, which places these normally tensioned structures under excessive load until failure occurs 1, 2.

The Key Volar Ligaments Include:

• Radioscaphocapitate ligament: Connects the radius to both the scaphoid and capitate; biomechanically important in neutral and pronated positions
• Radiolunate ligament (also called radiolunotriquetral): Strong connection from radius to lunate; acts as passive stabilizer in radial deviation
• Ulnolunate ligament: Connects ulnar structures to lunate; provides stability in ulnar deviation, supination, and extension
• Short radiolunate ligament: Deeper layer connecting radius to both scaphoid and lunate

3, 1

Biomechanical Context

These volar ligaments maintain baseline tension even in neutral, unloaded wrist positions 3. During FOOSH, the dorsiflexion force creates:

1. Compression injuries dorsally (scaphoid impaction, dorsal ganglions)
2. Tension injuries volarly with disruption or attenuation of the supporting palmar ligaments 4

The volar ligaments form functional units that, when disrupted, lead to specific instability patterns 5:

• Central sprain: Rupture of the palmar ligamentous "belt" causes anteroposterior radiocarpal or midcarpal drawer
• Lateral sprain: Involves distal scaphoid complex disruption, leading to scapholunate dissociation
• Medial sprain: Rupture of medial ligaments causes lunotriquetral pathology

Clinical Significance

The scapholunate ligament injury is the most common ligamentous wrist injury following FOOSH 6, 7. While the scapholunate ligament has both dorsal and volar components, the volar component (along with the radioscaphocapitate ligament that supports the scaphoid volarly) is vulnerable to tension failure during hyperextension.

Common Pitfall:

Clinicians often focus on dorsal structures in FOOSH injuries because of the dorsal compression mechanism. However, the volar ligaments fail under tension during the same hyperextension force, and these injuries are frequently missed on initial evaluation, leading to chronic instability and progression to scapholunate advanced collapse 6.

Diagnostic Approach

When evaluating suspected volar ligament injuries after FOOSH 8:

• Initial radiographs are mandatory but have limited sensitivity for ligamentous injury
• MRI (preferably 3T) shows moderate sensitivity (70% for scapholunate, 31% for lunotriquetral complete tears)
• MR arthrography at 1.5T has greater sensitivity than conventional MRI for complete tears
• Ultrasound can visualize volar ligaments but has limited ability to assess the structurally important volar band of the lunotriquetral ligament
• Dynamic imaging may be needed to detect instability patterns

The accuracy of MRI for extrinsic (volar radiocarpal) ligament assessment remains unknown, representing a diagnostic gap 8.