What is the differential diagnosis and management for ulnar side wrist pain after a finger jamming injury?

Differential Diagnosis for Ulnar-Sided Wrist Pain After Finger Jamming

The most likely diagnoses are triangular fibrocartilage complex (TFCC) tear, lunotriquetral ligament injury, ulnocarpal impaction syndrome, extensor carpi ulnaris (ECU) pathology, triquetral fracture, and distal radioulnar joint (DRUJ) injury. 1, 2, 3

Primary Differential Considerations

The ulnar side of the wrist has been termed the "black box" due to overlapping anatomy and complex differential diagnosis 2. After a finger jamming mechanism, consider these diagnoses systematically:

Most Common Pathologies (85% of cases)

• TFCC injuries - both traumatic and degenerative lesions produce ulnar-sided wrist pain 4, 2, 3
• Lunotriquetral ligament tears - common traumatic injury with overlapping presentation 2
• Ulnocarpal abutment syndrome (UCAS) - may be unmasked by acute trauma 3
• Triquetral fracture or non-union - direct trauma mechanism 3
• ECU tendon pathology - subluxation or tendinitis 3
• DRUJ arthritis or instability - acute or chronic 3
• Pisotriquetral arthritis - less common but important to identify 3

Clinical Examination Approach

Use the "storey concept" with the ulnar styloid as reference 1:

Lower Storey (DRUJ level)

• DRUJ instability or arthritis - assess with piano key test and forearm rotation 1
• Ulnar styloid pathology - palpate for tenderness 1

Intermediate Storey (Radiocarpal joint)

• TFCC tears - ulnar foveal sign has 89% sensitivity but only 48% specificity 3
• Ulnocarpal stress test - positive in multiple conditions, not sufficiently specific 3
• ECU pathology - patients localize pain better on pain charts 3

Upper Storey (Midcarpal/CMC joint)

• Lunotriquetral ligament injury - assess with ballottement test 1
• Pisotriquetral arthritis - pisotriquetral shear test has 100% sensitivity and 92% specificity 3

Diagnostic Imaging Algorithm

Initial Imaging

Obtain three-view wrist radiographs immediately (posteroanterior, lateral, and 45-degree semipronated oblique) to exclude fractures and assess ulnar variance 5. Two-view radiography is inadequate 5.

Advanced Imaging When Radiographs Are Normal or Nonspecific

For suspected TFCC or ligament injury, MRI without contrast is the appropriate next study 4:

• MRI is highly accurate for central TFCC disc lesions using high-resolution fast spin-echo or 3D gradient-recalled sequences 4
• 3.0T MRI may be more accurate than 1.5T for TFCC lesions 4
• Sensitivity for peripheral TFCC attachments and ulnar disc attachments is only fair with non-contrast MRI 4

MR arthrography has higher sensitivity than standard MRI for complete and incomplete lunotriquetral ligament tears 4, 6, 7:

• Direct contrast injection into radiocarpal joint or all three wrist compartments 4
• Better identifies which specific ligament segments are torn 4

CT arthrography is an alternative with similar or superior accuracy to MR arthrography for TFCC and intrinsic ligament lesions 4, 6, 7:

• Nearly 100% sensitivity and specificity for both scapholunate and TFCC lesions 7
• Less sensitive for extra-articular findings like ECU tendon abnormalities 4
• Appropriate when MRI contraindicated or metallic artifact present 4

Critical Diagnostic Pitfalls

• Do not rely on ulnar foveal sign or ulnocarpal stress test alone - these have poor specificity and are positive in multiple diagnoses including TFCC tears, UCAS, and DRUJ arthritis 3
• Clinical examination cannot reliably differentiate TFCC injuries, UCAS, DRUJ arthritis, and ECU pathology - these require MRI or CT for diagnostic confirmation 3
• Do not dismiss occult fractures based on initial negative radiographs - up to 30% of fractures are radiographically occult initially 5
• Pisotriquetral arthritis and ECU pathology - patients localize pain better on pain diagrams, which aids diagnosis 3

Management Principles

Conservative Management First

• Immobilization in neutral wrist and forearm position for 4 weeks 6, 7
• Gentle active motion at 4 weeks, strengthening at 8-12 weeks 6, 7

Surgical Intervention Indications

Arthroscopic foveal repair with suture anchor for peripheral TFCC tears (Palmer 1B) with foveal detachment restores anatomic attachment critical for DRUJ stability 6, 7:

• Allows concurrent treatment of associated injuries 6
• Post-operative immobilization for 4 weeks in neutral rotation 6, 7
• Return to heavy tasks minimum 3 months 6, 7

Expected Complications

• Dorsal sensory branch of ulnar nerve neuropraxia in 10% (fully recovers spontaneously) 6, 7
• Immobilization-related complications in 14.7% (generally minor) 6, 7