Triangular Fibrocartilage Complex Injury

The triangular fibrocartilage complex (TFCC) is the main stabiliser of the distal radioulnar joint (DRUJ) and a cushion between the ulnar carpus and ulnar head. Its parts are the articular disc, the dorsal and palmar radioulnar ligaments, the ulnocarpal ligaments, the meniscus homologue, the ulnar collateral ligament, and the extensor carpi ulnaris sheath. Injury causes ulnar sided wrist pain and DRUJ instability.

The Palmer classification separates traumatic injuries (class 1) from degenerative injuries (class 2). Class 1A is a central disc perforation, 1B is an ulnar avulsion (often with an ulnar styloid base fracture and DRUJ instability), 1C is a distal avulsion from the carpus, and 1D is a radial avulsion from the sigmoid notch. Class 2 injuries are ulnar impaction with progressive wear.

Traumatic injuries follow a fall on the pronated, extended wrist or a rotational load, and they accompany many distal radius fractures. They are common in gymnasts and racquet and throwing athletes. Degenerative tears affect older adults and people with ulnar positive variance.

Complications are chronic ulnar sided pain, DRUJ instability, ulnar impaction, arthritis, and extensor carpi ulnaris tendinopathy.

Pathophysiology.

The peripheral 10 to 40% of the disc and the ligament attachments have a blood supply, so peripheral tears can heal or be repaired. The central disc is avascular, so central tears do not heal and are debrided.

The foveal attachment of the radioulnar ligaments to the ulnar head is the main DRUJ stabiliser. Detachment of the deep fibres produces instability that a cast cannot control.

Ulnar sided wrist pain made worse by forearm rotation, ulnar deviation with loading, and gripping, with clicking or catching and weak grip. After a fracture or trauma there may be swelling and ulnar styloid tenderness.

• Ulnar foveal sign: tenderness in the soft depression between the ulnar styloid and flexor carpi ulnaris tendon, highly sensitive for foveal tears.
• DRUJ instability: ballottement of the ulnar head in pronation, neutral and supination, with comparison to the other side ("piano key" sign).
• Ulnocarpal stress test (axial load with ulnar deviation and rotation) and the press test (pain when pushing up from a chair).
• Check the extensor carpi ulnaris, lunotriquetral ligament and pisotriquetral joint.

• Radiographs: posteroanterior view in neutral rotation (ulnar variance) and a pronated grip view (dynamic ulnar variance), a lateral view, and signs of an ulnar styloid base fracture, DRUJ widening and arthritis.
• MRI (3 tesla) or MR arthrography shows the disc and the foveal attachment, with sensitivity of about 80 to 90%.
• CT of both wrists in rotation for DRUJ instability and sigmoid notch incongruity.
• Diagnostic wrist arthroscopy gives the definitive diagnosis and can treat at the same time.

Differential diagnosis.

• Ulnar impaction syndrome and extensor carpi ulnaris tendinopathy or subluxation.
• Lunotriquetral ligament tear and pisotriquetral arthritis.
• DRUJ arthritis, ulnar styloid fracture and hamate hook fracture.
• Ulnar neuropathy at Guyon canal and Kienböck disease.

Non-operative (acute, stable DRUJ, Palmer 1A or minor degenerative tears).

• Long arm or sugar tong splint with the forearm neutral to slightly supinated for 4 to 6 weeks, then physiotherapy for grip, proprioception and forearm strengthening.
• Corticosteroid injection into the ulnocarpal joint: methylprednisolone acetate 20 mg with 1 mL of lidocaine 1%, given once under aseptic technique (repeat no sooner than 3 months, maximum 3 injections in 12 months). Check glucose in diabetes, and avoid with infection or in the first 2 weeks after surgery. Warn about skin atrophy and depigmentation.
• Ibuprofen 400 mg orally every 8 hours with food for up to 5 to 7 days (maximum 1200 mg daily); avoid with eGFR under 30 mL/min/1.73 m2, peptic ulcer, heart failure or anticoagulant use.
• Paracetamol 1 g orally every 6 hours as needed (maximum 4 g daily; 3 g daily when weight is under 50 kg, with chronic alcohol use or hepatic impairment).

Surgery (failure of 3 months of non-operative care, or instability).

• Arthroscopic debridement of central tears (Palmer 1A).
• Repair of peripheral tears (1B, 1C, 1D) by an outside in or all-inside technique.
• Foveal reattachment (transosseous or anchor) for DRUJ instability. Fixation of a displaced ulnar styloid base fragment when it is accompanied by instability.
• Ulnar shortening osteotomy for ulnar positive variance with impaction.
• Tendon graft reconstruction of the radioulnar ligaments for chronic instability.
• After repair: cast in supination for 4 to 6 weeks, then gradual movement, with strength training at 3 to 4 months and return to sport at 4 to 6 months.

Operative antibiotic prophylaxis. Cefazolin 2 g intravenously (3 g when weight is 120 kg or over) within 60 minutes before incision as a single dose; with severe penicillin allergy, vancomycin 15 mg/kg intravenously starting 90 to 120 minutes before incision as a single dose, with creatinine checked in prolonged cases.

Monitoring. Pain, DRUJ stability and grip at 6 weeks, 3 months and 6 months. Radiographs after fixation of the ulnar styloid or an osteotomy at 6 weeks and 3 months. MRI when symptoms persist after 3 months of treatment. Return to sport and loading at 4 to 6 months.

Referral and escalation. Refer DRUJ instability, a displaced ulnar styloid base fracture with instability, and persistent pain after 3 months of conservative care to orthopaedics or hand surgery within 2 to 4 weeks. Urgent referral for an irreducible DRUJ, an open injury, or a TFCC injury with a distal radius fracture that needs fixation.

Special groups.

• Athletes: gymnasts and racquet players need an individual rehabilitation plan, and surgery is considered early after a foveal tear.
• Older adults: degenerative central tears are usually asymptomatic and need no treatment.
• Kidney impairment: avoid ibuprofen.
• Diabetes: monitor glucose after injection.