In 1981, Palmer and Werner introduced the term triangular fibrocartilage complex (TFCC) to describe the ligamentous and cartilaginous structures that suspend the distal radius and ulnar carpus from the distal ulna (see the image below).[1] The TFCC is the major ligamentous stabilizer of the distal radioulnar (DRU) joint and the ulnar carpus.

Functions of the TFCC are as follows:

It provides a continuous gliding surface across the entire distal face of the two forearm bones for flexion-extension and translational movements
It provides a flexible mechanism for stable rotational movements of the radiocarpal unit around the ulnar axis
It suspends the ulnar carpus from the dorsal ulnar face of the radius
It cushions the forces transmitted through the ulnocarpal axis
It solidly connects the ulnar axis to the volar carpus 

Since 1777, when DeSault's original dissertation first described DRU joint injuries, much has been written about this joint and the TFCC. As Palmer pointed out,[1, 2, 3] humans are differentiated from lower primates by a radiocarpal joint with a TFCC interposed between the ulna and carpus.[1] This TFCC improves wrist functional stability and allows six degrees of freedom at the wrist—flexion, extension, supination, pronation, and radial and ulnar deviation.

As interest in the TFCC evolved, open repair techniques for this structure were devised. Small- joint arthroscopy provides the opportunity for new techniques in the debridement or repair of these structures

Injuries to the TFCC present as ulnar-side wrist pain, frequently with clicking. Torn TFCCs constitute 35% of intra-articular fractures and 53% of extra-articular fractures. There is no correlation between ulnar styloid fractures and TFCC injuries. Patients with a torn TFCC display ulnar variance (radial shortening) that is on average 4.6 mm (vs 2.5 mm for no tear) and dorsal angulation of 24° (vs 12° for no tear).

Mikic looked at 180 wrist joints in 100 cadavers, ranging in age from fetuses to 94 years.[4] He demonstrated that degeneration of the TFCC begins in the third decade of life and progressively increases in frequency and severity in subsequent decades. After the fifth decade of life, he noted no normal-appearing TFCCs. Viegas and Ballantyne found similar results.[5]

Causative conditions for TFCC injuries include the following:

Falls onto pronated hyperextended wrist
Power-drill injuries in which the drill binds and rotates the wrist instead of the bit
Distraction force applied to the volar forearm or wrist
Distal radius fractures

Palmer and Werner looked at the axial load distribution through the distal radius and ulna[6] and demonstrated that with normal axial loading, 20% of the force is transmitted through the ulna and 80% through the radius. Their data also illustrated that small changes in relative ulnar length can significantly alter load patterns across the wrist. For example, with a distal radius fracture that settles 2.5 mm, an increase in ulnar axial load of approximately 40% can be expected.

Palmer, Werner, Glisson, and Murphy demonstrated that the percentage of axial force transmitted through the ulna decreases by sequential removal of the horizontal portion of the TFCC.[7] This percentage decrease is accentuated with more positive ulnar variance.

In a cadaver study, Adams demonstrated that no significant kinematic or structural changes resulted from an excision that did not violate the peripheral 2 mm of the disk and that constituted less than two thirds of the disk area.[8]

TFCC tears are associated with a positive ulnar variance. Ulnar variance increases with pronation and grip and decreases with supination.

The floor of the extensor carpi ulnaris (ECU) tendon sheath broadly connects with the TFCC. After release of the TFCC from its distal ulna attachment, Tang demonstrated a 30% increase in ECU tendon excursion during wrist extension.[9] This suggests the following:

The TFCC is an important pulley for the ECU tendon
Disruption of the normal ECU excursion may contribute to abnormal loading and force transmission through the ulnar wrist and TFCC

The history of TFCC injuries includes ulnar-side wrist pain (frequently accompanied by clicking), a fall or trauma, and/or mechanical symptoms that improve with rest and worsen with activity.

In the physical examination, look for the following:

Painful grinding or clicking with wrist range of motion (ROM)
Weakness
Ulnar deviation of the wrist with the forearm in neutral produces ulnar wrist pain and occasional clicking (perform a TFCC compression test)
Instability of the DRU joint with shucking the distal radius and ulna between the examiner's fingers (perform a DRU joint stress test; always compare this with the opposite wrist)
Piano key sign, which is a prominent and ballottable distal ulna with full pronation of the forearm
Ulnar carpal sag
Lunotriquetral (LT) interval tenderness
Positive LT ballottement or shuck test
ECU tendon subluxation

The history of TFCC injuries includes ulnar-side wrist pain (frequently accompanied by clicking), a fall or trauma, and/or mechanical symptoms that improve with rest and worsen with activity.

In the physical examination, look for the following:

Painful grinding or clicking with wrist range of motion (ROM)
Weakness
Ulnar deviation of the wrist with the forearm in neutral produces ulnar wrist pain and occasional clicking (perform a TFCC compression test)
Instability of the DRU joint with shucking the distal radius and ulna between the examiner's fingers (perform a DRU joint stress test; always compare this with the opposite wrist)
Piano key sign, which is a prominent and ballottable distal ulna with full pronation of the forearm
Ulnar carpal sag
Lunotriquetral (LT) interval tenderness
Positive LT ballottement or shuck test
ECU tendon subluxation

As the name suggest, the TFCC is triangular in shape. Palmer found an inverse relation between ulnar variance and TFCC thickness of the TFCC: The TFCC is thicker in individuals who are ulnar minus.[7] Generally, the TFCC is 1-2 mm thick at its center. This may thicken to 5 mm where the TFCC inserts into the eccentric concavity of the ulnar head and projecting styloid.

The TFCC extends ulnarly to insert into the base of the ulnar styloid. Distally, it inserts into the lunate via the ulnolunate (UL) ligament and the triquetrum via the ulnotriquetral (UT) ligament , hamate, and base of the fifth metacarpal. Radially, the TFCC arises from the ulnar margin of the lunate fossa of the radius.

The ulnocarpal portion of the TFCC is composed of the discus articularis and the UL and UT ligaments (referred to by some as the disk carpal ligaments). Embryologic studies have demonstrated that these ligaments arise from the disk and are critical to the carpal suspensory function of the TFCC.

The dorsal and palmar branches of the anterior interosseous artery and dorsal and palmar radiocarpal branches from the ulnar artery supply blood to the periphery of the TFCC. These vessels supply the TFCC in a radial fashion, with histologic sections demonstrating that the vessels penetrate the peripheral 10-40% of the disk. The central portion and radial attachment are avascular.

Mikic demonstrated that the percentage of the peripheral disk that is vascularized is reduced from one third in a young patient to one fourth in patients of advanced age.[4]

Because the periphery of the TFCC has a good blood supply, tears in this region can be repaired. By contrast, tears in the central avascular area must be debrided because they have no potential for healing.

The richly vascularized DRU ligament and palmar radioulnar (PRU) ligament are composed of thick, longitudinally oriented collagen fiber bundles that blend in with the central avascular fibrocartilaginous portion.

When the TFCC is viewed during wrist arthroscopy, the styloid attachment appears folded. Some of the blood vessels to the TFCC enter between these folds. This fold, combined with the vascular hilum, is termed the ligamentum subcruentum, which actually is the confluence of the TFCC and the V-shaped ligament (disk ligament) as it extends from the hilar area of the styloid to its twin insertions on the lunate and triquetrum.

From a distal perspective, the TFCC has two distinct insertions into the ulna—a superficial portion and a deep portion. The superficial components, the DRU and PRU ligaments, insert into the base of the styloid. The deep portion, the ligamentum subcruentum, inserts into the fovea near the axis of forearm rotation.

Repairing TFCC tears is contraindicated in the presence of infection or degeneration. Palmer class 2 degenerative TFCC tears (see the Palmer classification for TFCC abnormalities in Medical therapy) represent a pathologic progression of disease associated with ulnar impaction syndrome.

Degeneration of the TFCC is found with repetitive pronation and axial grip loading in association with ulnar positive variance and impaction between the ulnar head and the proximal pole of the lunate. Treatment of degenerative TFCC tears associated with ulnar impaction syndrome consists of nonoperative treatment first with immobilization, avoidance of aggravating activities, and nonsteroidal anti-inflammatory drugs (NSAIDs).

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 is contraindicated, as this would require resection of intact TFCC to perform the procedure or require performing the procedure entirely through the DRU joint portals.

The surgical indications for an arthroscopic wafer procedure are a Palmer class 2C or 2D lesion in an ulnar positive variance of not more than 2 mm without evidence of lunate-triquetrum instability. If lunate-triquetrum instability is present, this is addressed with formal ulnar shortening in an attempt to tighten the ulnocarpal ligaments and decrease the motion between the lunate and triquetrum.

For patients with an ulnar positive variance of more than 2 mm, formal ulnar shortening is performed. For patients with ulnar neutral or negative variance and a Palmer class 2C lesion, an arthroscopic debridement 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 that addresses the DRU joint and LT joint pathology.

Plain radiography
Obtain neutral forearm rotation posteroanterior (PA) and lateral x-rays of the wrist to allow assessment of ulnar variance and to assess for chondromalacia of the lunate or ulnar head, degenerative joint disease of the distal radioulnar (DRU) joint, lunotriquetral (LT) or scapholunate (SL) instability, dorsiflexed intercalated segment instability (DISI), or volar flexed intercalated segment instability (VISI).

Wrist arthrography
The accuracy and diagnostic capability of triple-injection wrist arthrograms have been challenged over the past decade. The test is not specific, with a high incidence of findings on the contralateral asymptomatic side. Wrist arthrography has poor diagnostic agreement with chronic wrist pain.

Positive wrist arthrograms are obtained in 27% of asymptomatic adults. Palmer class 1B tears have positive arthrograms with a DRU joint injection but not with a radiocarpal injection. Palmer class 1C tears have variable findings. Palmer class 1D tears usually have positive arthrograms.

Magnetic resonance imaging
Magnetic resonance imaging (MRI) can predict TFCC lesions with 0.8 sensitivity and 0.7 specificity using a dedicated wrist coil.[10, 11, 12] Fat suppression MRI scans best exhibit the complex structure of the TFCC.

Wrist arthroscopy is the criterion standard; it can be a diagnostic tool or a therapeutic tool. When compared with other imaging studies, wrist arthroscopy is more accurate. It also allows assessment of the size of the tear, determination of whether an unstable flap is present, and detection of associated synovitis and chondral and ligamentous lesions.

With the trampoline test, normally a probe should bounce off of the TFCC. If a probe sinks into the TFCC as if it is on a feather bed, a tear is usually present.

Wrist arthroscopy is used in the diagnosis of TFCC tears associated with distal radius fractures. Richards examined 118 fractures[13] ; these fractures had wrist arthroscopy that required reduction and fixation because of a failure to obtain or maintain a reduction.

Lee Master et al undertook a study to determine the accuracy of the wrist insufflation test on the basis of mean radiocarpal and midcarpal joint space volumes in 29 patients who underwent three- or four-portal radiocarpal and radial midcarpal portal insufflation before wrist arthroscopy.[14] They concluded that the test allowed detection of complete scapholunate interosseous ligament and triangular fibrocartilage complex tears and complete scapholunate interosseous ligament and lunotriquetral interosseous ligament tears.

Arthroscopic repair
A review by de Araujo et al of 17 patients after arthroscopic repair of Palmer class IB tears, with an average patient age of 33 years, showed that at 8 months follow-up, 16 patients (48%) were satisfied or very satisfied; one patient was not satisfied. At 16-24 months' follow-up, 70% of the patients were satisfied.[29]

Reiter et al performed a retrospective study of 46 patients who underwent arthroscopic repair of Palmer class IB tears to determine patients' functional and subjective outcomes, as well as whether clinical outcomes were related to ulnar length. Good-to-excellent results were achieved in 63% of the patients, including increased range of motion and grip strength and pain relief. Ulnar neutral or positive variance was not a contraindication for repair and did not necessitate simultaneous ulnar shortening.[22]

Sagerman and Short reviewed 12 patients after arthroscopic repair of Palmer class ID tears, with an average follow-up of 17 months, and found good or excellent results in 67% of patients.[30]

Trumble et al reviewed 24 patients after arthroscopic repair of Palmer classes IB, IC, and ID tears. The average patient age was 31 years. Treatment occurred within 4 months after injury, with a follow-up of 34 months. Postoperative range of motion was 89%, and grip strength was 85%. Thirteen of 19 patients returned to their original jobs or sports. Follow-up studies demonstrated that the TFCC was intact in 12 of 15 patients.[31]

Corso et al reviewed 44 patients (average age, 32.5 years) and 45 wrists with zone-specific repair and follow-up of 37 months and found excellent results in 29 patients, good results in 12, fair results in one, and poor results in three.[32]

In a study from 2001 through 2005 of 16 competitive athletes with wrist TFCC, McAdams et al found that arthroscopic debridement or repair of TFCC injury provided pain relief and allowed patients to return to play, with slower recovery in patients with concomitant ulnar-sided wrist injuries.[8] .

Yao et al compared an all-arthroscopic TFCC repair technique with an outside-in technique in 10 matched pairs of fresh-frozen cadaveric wrists and found that the all-arthroscopic technique resulted in decreased operative time; reduced postoperative immobilizations; and decreased irritation from suture knots below the skin.[33, 34]

In a study of 75 patients with TFCC repair by arthroscopic or open technique between 1997 and 2006, Anderson et al found that there was no statistical difference in clinical outcome for arthroscopic and open techniques for TFCC repair. They did note an increased rate of postoperative superficial ulnar pain in patients who underwent open repair (14 of 39 patients with open technique, vs 8 of 36 patients with arthroscopy). Females had a higher rate of reoperation.[35]

In a cadaveric study comparing the biomechanical strength of knotless suture anchor repair and the traditional outside-in repair of peripheral TFCC tears, Desai et al concluded that the all-arthroscopic suture anchor TFCC repair was biomechanically stronger than the outside-in repair and that the former allowed repair of both superficial and deep layers of the articular disk directly to bone, thereby restoring native TFCC anatomy.[36] They suggested that the absence of knots might prevent irritation to the surrounding soft tissues.

Arthroscopic debridement
Minami et al reviewed 16 patients (average age, 30 years) with a follow-up of 35 months. Palmer class 1 tears were found in 11 patients, and Palmer class 2 tears were found in 5 patients. Of the 16 patients, 13 returned to their previous jobs. Ulnar positive and LT tears were associated with a poor outcome; Palmer class 1 tears were associated with excellent results; and Palmer class 2 tears were associated with poor results.[37]

Westkaemper et al reviewed 28 patients (average age, 30 years) with a follow-up of 15.4 months. Excellent results were found in 13 patients, with good results in 8 patients, fair results in 2 patients, and poor results in 5 patients.[38]

De Smet et al conducted a retrospective survey of 46 patients who underwent debridement with or without wafer distal ulna resection.[39] Patients were sent a questionnaire on pain, disability, and time off from work. Mean scores on the Disabilities of the Arm, Shoulder, and Hand (DASH) scale decreased from 42 to 28. The pain was considered severe in 12 patients; 32 patients were satisfied. There were significant differences in the outcome between use of debridement only and use of debridement with wafer resection of the distal ulna.

Ulnar shortening
Minami and Kato reviewed 25 patients (average age, 32 years) with follow-up of 35 months. Ulnar variance averaged more than 3.5 mm. Ulnar shortening osteotomies of 3 mm, fixed with a 6-hole 3.5-mm dynamic compression plate (DCP), were performed. Twenty-three patients also had arthroscopy. Palmer class 1 tears were found in 15 patients; only the flap was removed. Palmer class 2 tears were found in 8 patients; no debridement was performed.

Complete relief or only occasional mild pain was found in 23 patients. Of the 25 patients, 23 returned to their original work. Osteotomies healed at an average of 7 weeks. This research suggests that ulnar shortening is indicated in both traumatic and degenerative tears associated with ulnar positive variance.[40]

Trumble et al reviewed 21 patients with treatment delays longer than 6 months and follow-up of 29 months. Palmer class 1 tears were repaired. Ulnar shortening osteotomies of 2-3 mm fixed with 6-hole 3.5-mm DCPs were performed. Complete pain relief was found in 19 of 21 patients. Grip strength was 83%; range of motion was 81% of normal. Treatment delays longer than 6 months from the time of injury resulted in a higher recurrence of symptoms; in these situations, the authors recommended combining arthroscopic repair with ulnar shortening.[41]

Hulsizer et al reviewed 97 patients (average age, 34 years; average ulnar variance, 0.4 mm) with central or nondetached ulnar peripheral tears initially treated with debridement. Persistent pain more than 3 months after surgery was reported by 13 patients. A 2-mm ulnar shortening osteotomy, fixed with a 6-hole 3.5-mm DCP, was performed on these 13 patients. . Complete pain relief at 2.3-year follow-up was reported by 12 of the 13 patients. An ulnar shortening osteotomy of 2 mm was recommended for patients in whom arthroscopic debridement failed.[42]

In a retrospective study involving 256 patients, Yamanaka et al compared preoperative and postoperative TFCC thickness and TFCC angle, using magnetic resonance imaging (MRI) to quantitatively evaluate the effect of ulnar shortening osteotomy on disk regeneration and the suspension effect on the TFCC.[43] They found that ulnar shortening osteotomy yielded a high residual potential for regeneration in the disk proper. There was no correlation between disk regeneration or the suspension effect on the TFCC and the Mayo wrist score.

A large controversy exists concerning the biomechanical changes of the TFCC during pronation and supination. A number of authors claim that the dorsal RUL tightens during pronation and relaxes with supination. Others claim the exact opposite.

Nakamura may have solved this question by using a custom-made surface coil allowing complete freedom of wrist motion. From MRI scans of the wrist in coronal and sagittal planes at maximal pronation and neutral and maximal supination, he showed that during pronation and supination, the TFCC twists at its origin.[44] This should result in friction between the proximal side of the disk proper and the ulnar head during rotation. The friction may increase in ulnocarpal abutment syndrome because of ulnar variance, potentially explaining the degeneration seen in Palmer class 2 TFCC tears.