TFCC Injuries

The triangular fibrocartilage complex (TFCC) is the primary stabiliser of the distal radioulnar joint (DRUJ) and a key load transmitter across the ulnar side of the wrist. Injuries to the TFCC are a common but frequently underdiagnosed cause of ulnar-sided wrist pain. Accurate anatomical knowledge and systematic classification are essential for appropriate management.

• The TFCC is a complex of structures spanning from the ulnar notch of the radius to the ulnar styloid, fovea, and ulnar carpus
• Components: articular disc (triangular fibrocartilage proper), dorsal and volar radioulnar ligaments (deep and superficial), ulnocarpal ligaments (ulnolunate and ulnotriquetral), meniscus homologue, extensor carpi ulnaris (ECU) subsheath
• The deep fibres of the dorsal and volar radioulnar ligaments insert at the fovea of the ulnar head — these are the primary DRUJ stabilisers
• Superficial fibres insert at the ulnar styloid — less critical for DRUJ stability
• The central disc is avascular — heals poorly; peripheral third has vascular supply from ulnar artery branches — better healing potential
• TFCC transmits approximately 18% of axial load across the wrist; this increases significantly with positive ulnar variance
• Positive ulnar variance increases TFCC load — for every 1 mm increase in ulnar variance, load on TFCC increases by approximately 10–15%

The Palmer classification (1989) remains the most widely used system. It divides TFCC injuries into traumatic (Class 1) and degenerative (Class 2).

• Class 1B (foveal avulsion) = DRUJ instability — requires surgical repair; most clinically significant traumatic subtype
• Class 1A (central tear) — no instability; treat non-operatively or arthroscopic debridement if symptomatic
• Degenerative Class 2 injuries associated with ulnar impaction syndrome — positive ulnar variance is the underlying driver

• History: mechanism (axial load + forearm rotation, FOOSH, distraction), dominant hand, occupation, sport, prior wrist injury, symptom duration
• Ulnar-sided wrist pain: aggravated by forearm rotation, grip, and ulnar deviation
• DRUJ instability symptoms: painful clunk, giving way, difficulty with grip and rotation tasks
• Fovea sign (Tay): direct tenderness in the soft spot between FCU, ulnar styloid, and pisiform — sensitivity 95.2%, specificity 86.5% for foveal TFCC tear
• Piano key test: DRUJ ballottement in neutral forearm rotation — assesses dorsopalmar DRUJ instability; compare with contralateral side
• Press test: patient pushes up from chair using both hands — pain on affected side suggests TFCC pathology
• Ulnocarpal stress test: axial load and ulnar deviation with forearm rotation — reproduces ulnar impaction symptoms
• Assess DRUJ stability in both neutral and full pronation/supination — instability in all positions suggests complete TFCC disruption

• Plain radiographs (PA in neutral rotation and grip views): assess ulnar variance, DRUJ congruity, carpal alignment, distal radius malunion; measure ulnar variance on true PA with shoulder abducted 90°, elbow flexed 90°, wrist in neutral
• MRI wrist (3T preferred): sensitivity 75–100% for full-thickness TFCC tears; less reliable for partial tears; assess foveal attachment, DRUJ, lunotriquetral (LT) ligament, ulnocarpal ligaments
• MR arthrogram: improves sensitivity for peripheral and partial tears — gadolinium leaks through tear; gold standard non-invasive investigation
• CT arthrogram: excellent for DRUJ assessment and bony anatomy; less soft tissue detail than MR arthrogram
• Diagnostic wrist arthroscopy: gold standard — direct visualisation, probing of TFCC, hook test (pulls TFCC radially; lack of tension = foveal detachment), trampoline test (bounce of central disc reflects peripheral tension)
• Hook test at arthroscopy: positive hook test = foveal detachment (Palmer 1B) — indicates need for foveal repair rather than peripheral repair alone

Treatment is guided by Palmer classification, DRUJ stability, ulnar variance, and patient demands.

• Ulnar shortening osteotomy (USO): preferred procedure for ulnar impaction — reduces ulnar variance by 2–4 mm; reliably reduces TFCC load; can be combined with arthroscopic debridement; high union rate
• Wafer procedure: arthroscopic resection of 2–4 mm of distal ulnar head through TFCC tear — less predictable than USO; indicated for <2 mm positive variance
• Darrach procedure: distal ulna resection — salvage for DRUJ arthritis; risks DRUJ instability and convergence; avoid in young active patients
• Sauvé-Kapandji: arthrodesis of DRUJ with creation of pseudarthrosis of distal ulna — maintains ulnar support; preferred over Darrach in younger patients with DRUJ arthritis
• Foveal repair (Palmer 1B with instability) — transosseous suture through fovea; best results within 3 months of injury

• Peripheral vs foveal repair distinction is critical: peripheral repair (outside-in or inside-out suture at peripheral attachment) does not restore foveal deep fibre tension — DRUJ may remain unstable; always perform hook test arthroscopically to exclude foveal detachment
• Combined peripheral tear and foveal detachment — foveal repair takes priority for DRUJ stability; peripheral repair alone insufficient
• Distal radius malunion: if positive ulnar variance is secondary to distal radius malunion, corrective osteotomy of the radius restores normal variance and unloads TFCC — preferred over USO in this scenario
• ECU subsheath injury: commonly co-exists with TFCC tears; causes ECU instability and snapping — assess ECU separately; repair subsheath if symptomatic instability confirmed
• LT ligament tears (Palmer 2D): partial LT tears can be treated with arthroscopic debridement; complete LT tears with instability require repair or LT arthrodesis; distinguish from TFCC tear clinically using Shuck test (LT ballottement)
• Post-surgical rehabilitation: long arm cast in supination for 4–6 weeks after foveal repair; forearm neutral after peripheral repair; supervised physiotherapy essential for DRUJ stabilisation exercises

• TFCC transmits 18% of axial wrist load — increases with positive ulnar variance
• Deep fibres at fovea = primary DRUJ stabilisers; superficial fibres at styloid = secondary stabilisers
• Palmer 1B = foveal avulsion = DRUJ instability = surgical repair required
• Palmer 1A = central avascular tear = no instability = debridement if symptomatic
• Fovea sign: tenderness between FCU, ulnar styloid and pisiform — sensitivity 95% for foveal tear
• Hook test at arthroscopy: positive = foveal detachment — requires foveal repair not just peripheral repair
• Ulnar impaction syndrome (Palmer 2): positive ulnar variance driving degenerative TFCC wear — treat with USO
• Sauvé-Kapandji preferred over Darrach in young patients with DRUJ arthritis — preserves ulnar support
• MR arthrogram = gold standard imaging; diagnostic arthroscopy = gold standard overall
• Foveal repair: best results within 3 months of injury — do not delay in unstable DRUJ