The triangular fibrocartilage complex suspends the ends of the radius and ulna bones over the wrist. It is triangular in shape and made up of several ligaments and cartilage. It acts as a major ligamentous stabilizer of the distal radioulnar joint and the ulnar side of wrist bones.
The Triangular fibrocartilage complex makes it possible for the wrist to move in six degrees of freedom – flexion, extension, supination, pronation, and radial and ulnar deviation (bending, straightening, twisting, side-to-side).
Entire triangular fibrocartilage complex sits between the ulna and two carpal bones (the lunate and the triquetrum. The triangular fibrocartilage inserts into the lunate and triquetrum via the ulnolunate and ulnotriquetral ligaments. It stabilizes the distal radioulnar joint while improving the range of motion and gliding action within the wrist.
There is a small cartilage pad called the articular disc in the center of the complex that cushions this part of the wrist joint. Other parts of the complex include the dorsal radioulnar ligament, the volar radioulnar ligament, the meniscus homologue (ulnocarpal meniscus), the ulnar collateral ligament, the subsheath of the extensor carpi ulnaris, and the ulnolunate and ulnotriquetral ligaments.
Injury to the triangular fibrocartilage complex involves tears of the fibrocartilage articular disc and meniscal homologue [Piece of tissue that connects the disc to the triquetrum bone in the wrist].
There is no correlation between ulnar styloid fractures and triangular fibrocartilage complex injuries. Triangular fibrocartilage complex injuries are present in 35% of intra-articular fractures and 53% of extraarticular fractures.
Causes of Triangular Fibrocartilage Complex Tears
Trauma or a fall onto an outstretched hand on a pronated hand may result in triangular fibrocartilage complex injuries.High-demand athletes such as tennis players or gymnasts are at greatest risk. Power drill,when the drill binds and the wrist rotates instead of the drill bitcan result in tears of triangular fibrocartilage complex.
Triangular fibrocartilage complex tears can also occur with degenerative changes.
Repetitive pronation (palm down position) and gripping with load or force through the wrist are risk factors for tissue degeneration.
Distal radius fractures may also cause these injuries.
Triangular fibrocartilage complex tears are associated with a positive ulnar variance . Ulnar variance increases with pronation and grip and decreases with supination.
Palmer Classification for triangular Fibrocartilage Complex [TFCC] Abnormalities
Class 1 – Traumatic
- A – central perforation
- B – ulnar avulsion with or without distal ulnar fracture
- C – distal avulsion
- D – radial avulsion with or without sigmoid notch fracture
Class 2 – Degenerative (ulnocarpal abutment syndrome)
- A – TFCC wear
- B – TFCC wear with lunate and/or ulnar chondromalacia
- C – TFCC perforation with lunate and/or ulnar chondromalacia
- D – TFCC perforation with lunate and/or ulnar chondromalacia and LT ligament perforation
- E – TFCC perforation with lunate and/or ulnar chondromalacia, LT ligament perforation, and ulnocarpal arthritis
Ulnar-sided wrist pain (frequently accompanied by clicking) after a fall or trauma is major complaint. Physical examination would reveal painful grinding or clicking with wrist range of motion.
Ulnar deviation of the wrist with the forearm in neutral produces ulnar wrist pain. Sometimes clicking may also be elicited.
Distal radio ulnar joint may elicit instability with shucking the distal radius and ulna between the examiner’s fingers (DRUJ stress test).
Prominence of distal ulna may be noted. The distal ulna may be ballottable distal ulna in pronation.
Posteroanterior and lateral x-rays of the wrist would reveal ulnar variance and chondromalacia of the lunate or ulnar head, if any.
Degeneration of distal radioulnar joint and any wrist instability may be noted.
MRI is highly sensitive and specific for detecting fibrocartilage complex tears with fat suppression MRI scans best exhibiting the complex structure of triangular fibrocartilage complex. the complex structure of the TFCC.
Wrist arthroscopy is more accurate than imaging studies and allows for assessment of the size of the tear, for determining unstable flap and for detecting associated synovitis and chondral and ligamentous lesions.
Drugs and Immobilization
Initial treatment of both symptomatic degenerative and traumatic tears includes NSAIDs, immobilization in slight flexion and ulnar deviation in a short arm cast for 4-6 weeks. It is followed by removable wrist splints and physical therapy.
Wrist Arthroscopic Surgery
Indications for wrist arthroscopy include acute unstable tears, acute tears that fail to respond to conservative management, and chronic tears for which conservative management fails. The treatment either consists of repair or debridement.
In debridement, the surgeon debrides any tears of the disc or meniscal homologue that might catch against other joint surfaces. Arthroscopic debridement works well for simple tears.
In repair, ligamentous ruptures are be repaired arthroscopically with reattachment using wires and screws to help hold the repaired tissue in place until healing.
Few complex tears that require open repair. For example, detachment of the radioulnar ligaments usually requires open repair. Instability of the distal radioulnar joint may require the use of wires.
Ulnar Shortening Osteotomy
Ulnar shortening osteotomy is considered for patients with ulnar positive variance, failure of debridement and neglected cases presenting late.
Acute isolated triangular fibrocartilage complex disruption with dislocation or instability of the distal radioulnar joint is treated with reduction and then the forearm is immobilized in a long arm cast in the position of stability for 4-6 weeks.
Many patients with a mild triangular fibrocartilage complex injury are able to return to work and sports at a preinjury level.
Residual laxity may remain after nonoperative treatment of a TFCC injury. Surgery may be needed to restore normal wrist movement.
Repair is contraindicated in the presence of infection or degeneration.
Palmer class 2A and 2B lesions that fail to respond to conservative treatment are treated with gentle debridement. If the patient is ulnar positive and symptomatic, a formal ulnar shortening is considered.
An arthroscopic wafer procedure is considered for Palmer class 2C or 2D lesion in an ulnar positive variance of not more than 2 mm without evidence of lunate-triquetrum instability.
For patients with ulnar neutral or negative variance and a Palmer class 2C lesion, an arthroscopic debridement is performed.
If lunate-triquetrum instability is present, ulnar shortening may be done.
For patients with an ulnar positive variance of more than 2 mm, formal ulnar shortening is performed.
Palmer class 2E lesions respond unpredictably to arthroscopic debridement. They are usually treated with a salvage procedure such as a limited ulnar head resection, Sauve-Kapandji procedure, or Darrach procedure.