TFCC and Distal Radioulnar Joint (DRUJ)

Introduction

The Triangular Fibrocartilage Complex (TFCC) is a key stabilizing structure on the ulnar side of the wrist. It plays a critical role in:

• Distal radioulnar joint stability
• Load transmission across the wrist
• Smooth forearm rotation

Injuries to the TFCC commonly produce ulnar-sided wrist pain and instability.

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Triangular Fibrocartilage Complex (TFCC)

Definition

The TFCC is a fibrocartilaginous structure located on the ulnar side of the wrist.

It functions as:

• A cushion between the distal ulna and carpal bones
• The primary stabilizer of the distal radioulnar joint (DRUJ)

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Distal Radioulnar Joint (DRUJ)

Joint Type

• Synovial pivot joint

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Function

The DRUJ allows:

• Pronation
• Supination

During forearm rotation:

• The radius rotates around the relatively stable ulna

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Components of the TFCC

The TFCC is composed of several important structures:

• Central articular disc
• Meniscal homologue
• Dorsal radioulnar ligament
• Volar radioulnar ligament
• Ulnocarpal ligaments
• Contribution from the ECU tendon sheath

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Vascularity of the TFCC

Peripheral Region

• Well vascularized
• Better healing potential

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Central Region

• Avascular
• Poor intrinsic healing capacity

This difference is important in treatment planning.

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Functions of the TFCC

The TFCC performs several essential biomechanical roles:

• Stabilizes the DRUJ
• Transmits load from the carpus to the ulna
• Allows smooth forearm rotation
• Suspends and stabilizes the ulnar carpus

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Causes of TFCC Injury

Common mechanisms include:

• Fall on an outstretched hand (FOOSH)
• Distal radius fractures
• Degenerative wear
• Repetitive loading activities

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Clinical Features

Patients commonly present with:

• Ulnar-sided wrist pain
• Clicking or popping sensation
• Pain during pronation and supination
• Reduced grip strength
• DRUJ instability

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Clinical Examination Tests

Press Test

Method

The patient pushes upward from a chair using the hands.

Positive Test

• Reproduction of ulnar wrist pain suggests TFCC injury

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Piano Key Sign

Finding

• Increased mobility of the distal ulna head

Suggests DRUJ instability.

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Ballottement Test

Used to assess:

• DRUJ stability

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Fovea Sign

Location of Tenderness

Tenderness between:

• Ulnar styloid
• Flexor Carpi Ulnaris (FCU) tendon

This is highly sensitive for TFCC pathology.

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Imaging

X-ray

Useful to exclude:

• Fractures
• Degenerative arthritis
• Ulnar variance abnormalities

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MRI

Sensitivity ranges approximately from:

• 74% to 100%

Useful for identifying TFCC tears.

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Gold Standard

• Wrist arthroscopy

Provides direct visualization of the TFCC and DRUJ.

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Palmer Classification

Type 1 – Traumatic Lesions

Type 1A

• Central tear
• Occurs in avascular region

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Type 1B

• Ulnar-sided avulsion

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Type 1C

• Distal ulnocarpal ligament tear

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Type 1D

• Radial-sided avulsion

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Type 2 – Degenerative Lesions

Associated with:

• Ulnar positive variance
• Chronic ulnocarpal loading

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Treatment

Conservative Management

Initial treatment usually includes:

• Rest
• Wrist or thumb spica splint
• NSAIDs
• Steroid injection

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Surgical Treatment

Type 1A Central Tears

Because the central region is avascular:

• Arthroscopic debridement is preferred

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Peripheral Tears (1B, 1C, 1D)

Because the peripheral region is vascular:

• Arthroscopic repair
• Open repair

may be performed.

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Management of Ulnar Positive Variance

More Than 2 mm Positive Variance

• Ulnar shortening osteotomy

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Less Than 2 mm Positive Variance

• Wafer procedure
  • Open or arthroscopic

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Salvage Procedure

Darrach Procedure

• Resection of distal ulna

Usually reserved for:

• Elderly patients
• Severe arthritis
• Salvage situations

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DRUJ Instability

Important Clinical Point

The DRUJ should always be assessed after distal radius fracture fixation.

Persistent instability may require:

• Temporary K-wire stabilization

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Important Differential Diagnoses

1. Ulnocarpal Impaction Syndrome

Associated with:

• Ulnar positive variance
• Chronic ulnocarpal overload

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2. Extensor Carpi Ulnaris (ECU) Pathology

May produce:

• Ulnar-sided wrist pain
• Snapping or instability

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3. Triquetral Impingement Ligament Tear (TILT)

Features

• Ulnar wrist pain
• Normal X-rays

Treatment

• Excision of fibrous tissue

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Key Clinical Points

• The TFCC is the primary stabilizer of the DRUJ.
• Peripheral TFCC tears heal better because of vascularity.
• Central tears are usually treated with debridement rather than repair.
• Always evaluate DRUJ stability after distal radius fractures.
• Wrist arthroscopy remains the gold standard for diagnosis and treatment.