TFCC Injuries
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Direct answer
A triangular fibrocartilage complex injury is a tear or degeneration of the structure that stabilises the distal radioulnar joint and cushions the ulnar side of the wrist, and it causes pain on the ulnar side. The Palmer classification divides these lesions into traumatic type 1 and degenerative type 2. Tenderness over the ulnar fovea and pain on ulnar loading with rotation are the key clinical signs.
What you must remember
- Components: the articular disc, the dorsal and volar radioulnar ligaments, the meniscal homologue, the ulnar collateral ligament and the ulnolunate and ulnotriquetral ligaments.
- Palmer type 1: traumatic lesions, often from a fall on an outstretched hand, which may be central, peripheral or an ulnar or radial avulsion.
- Palmer type 2: degenerative lesions that wear the disc, often with a positive ulnar variance.
- Ulnar fovea test: pressing the ulnar fovea, the soft spot between the ulnar styloid and the flexor carpi ulnaris tendon, reproduces the pain of a TFCC tear.
- Ulnar variance: a positive value on a neutral posteroanterior radiograph predisposes to ulnar impaction.
- Ulnar impaction syndrome: ulnar-sided wrist pain with loading in a patient with positive ulnar variance, treated by ulnar shortening osteotomy when conservative care fails.
- Blood supply: the peripheral third has a blood supply and may heal, while the central avascular zone generally does not.
A pathway for ulnar-sided wrist pain
Ulnar-sided wrist pain has several causes, and the TFCC is one of the commonest. The steps below follow the order in which a hand surgeon separates the diagnosis from its alternatives and decides between conservative and operative care.
- Examine the ulnar wrist: test ulnar fovea tenderness and pain on ulnar loading with rotation, and assess the distal radioulnar joint.
- Measure the ulnar variance: a standard posteroanterior radiograph in neutral rotation shows whether the ulna is long relative to the radius.
- Image the disc: MR arthrography shows the tear, and wrist arthroscopy is both diagnostic and therapeutic.
- Treat peripheral tears conservatively: short immobilisation and rest are used for acute peripheral tears, which have a blood supply and can heal.
- Debride or repair: arthroscopic debridement is the usual treatment for central tears, and repair is considered for selected peripheral tears.
- Correct ulnar impaction: an ulnar shortening osteotomy off-loads the ulnar side in symptomatic positive ulnar variance.
Where the exam tries to catch you
TFCC questions reward the anatomy of blood supply and the logic of the ulnar variance.
- Trap: repairing every central tear. Correct: central tears lie in the avascular zone and usually do not heal, so arthroscopic debridement is the typical treatment.
- Trap: assuming a positive ulnar variance always needs surgery. Correct: positive ulnar variance is a risk factor, and an ulnar shortening osteotomy is reserved for symptomatic impaction after conservative care.
- Trap: using a plain radiograph alone to diagnose a TFCC tear. Correct: radiographs show ulnar variance and fractures but not the disc itself, so MR arthrography or arthroscopy is needed.
Frequently asked questions
Which classification grades TFCC injuries?
The Palmer classification grades TFCC injuries into traumatic type 1 and degenerative type 2 lesions. Type 1 lesions are subdivided by the site of the tear, and type 2 lesions are subdivided by the degenerative changes. The classification guides the choice between conservative care and surgical treatment.
What is the ulnar fovea sign in a TFCC injury?
The ulnar fovea sign is tenderness on pressure over the ulnar fovea, the soft spot between the ulnar styloid and the flexor carpi ulnaris tendon. Reproduction of pain at this point is a sensitive clinical sign of a TFCC injury. It is usually assessed with the forearm in neutral and the wrist examined for pain on loading.
What is ulnar impaction syndrome and how is it treated?
Ulnar impaction syndrome is ulnar-sided wrist pain caused by repeated loading of a long ulna against the carpus, typically in a patient with positive ulnar variance. It is treated first with rest and orthoses, and an ulnar shortening osteotomy is used when symptoms persist. The osteotomy off-loads the ulnar side of the wrist.
Why do central TFCC tears heal poorly?
Central TFCC tears heal poorly because the central part of the disc lies in the avascular zone, which has no direct blood supply. Without a blood supply, the repair has little capacity to heal. Arthroscopic debridement is therefore the usual treatment, rather than repair.