Introduction

Ulnar-sided wrist pain is a common disorder that encompasses a broad range of diagnoses. One cause of ulnar-sided wrist pain can be triangular fibrocartilage complex (TFCC) trauma. The TFCC and its supporting ligaments suspend the ulnar carpus, bear carpal load through the wrist to the ulna, and permit the carpus and radius to rotate as a unit around the axis of the ulna.

Because the TFCC plays a vital role in normal wrist function, any injury that does not heal on its own can lead to pain, stiffness, loss of strength, and significant patient dissatisfaction. The TFCC is frequently compared to the menisci of the knee because they have similar biomechanical roles, biochemical composition, diminished blood supply, and poor intrinsic healing capacity. As in the meniscus, peripheral tears of the TFCC are more amenable to healing after repair than central lesions due to a greater peripheral blood supply. Arthroscopic repair techniques for peripheral tears of the TFCC have been shown to provide a successful and minimally invasive approach to a difficult problem.

Anatomy and Biomechanics

The anatomy of the triangular fibrocartilage complex (TFCC) is primarily composed of the articular disc (or triangular fibrocartilage), a meniscus homologue, dorsal and volar radioulnar ligaments, the extensor carpi ulnaris (ECU) tendon subsheath, and the ulnocarpal ligaments (ulnolunate, ulnotriquetral, and ulnocapitate)—as depicted in Figures 5.1 and 5.2. The triangular fibrocartilage is a meniscus-like structure composed predominantly of type I collagen. Surrounding the periphery of the triangular fibrocartilage is the meniscal homologue, a fibrocartilaginous rim of dense irregular connective tissue that confluences with the dorsal and volar radioulnar ligaments.¹

FIGURE 5.1 The distal radioulnar ligaments extend from the sigmoid notch of the distal radius to the base of the ulnar styloid. The triangular fibrocartilage is suspended between these ligaments.

FIGURE 5.2 An open approach to the TFCC typically occurs between the fifth (extensor digiti minimi or EDM) and sixth (extensor carpi ulnaris or ECU) compartments. After flap exposure of the dorsal joint capsule overlying the DRUJ, the TFCC as well as the ulnar carpus can be visualized (USN = dorsal sensory branch of the ulnar nerve, UCL = ulnocarpal ligaments, Tq = triquetrum, L = lunate, LT = lunotriquetral, R = radius, U = ulna, EIP = extensor indicis proprius, TFCC = triangular fibrocartilage complex).

The ligaments and the triangular fibrocartilage form a three-walled structure that supports the distal radioulnar joint and ulnar portion of the carpus. The TFC, with its bordering volar and dorsal radioulnar ligaments, acts as the base of this structure. These ligaments originate as a unit from the fovea of the ulnar head and the very base of the ulnar styloid (Figure 5.3) and diverge distally into dorsal and volar stabilizers for the distal radius as it rotates around the distal ulna to achieve forearm rotation.² The ulnotriquetral, ulnolunate, and ulnocapitate ligaments form the volar wall of this box, and the dorsal radial triquetral ligament (along with the dorsal fibers of the ECU subsheath) forms the dorsal wall.

FIGURE 5.3 A normal MRI demonstrates the insertion of the distal radioulnar ligaments of the TFCC at the ulnar fovea and base of ulnar styloid (marked by the asterisk).

The dorsal ECU subsheath has Sharpey fiber connections to the ulnar head at the fovea.² The ulnar fibers of the ECU subsheath make up the ulnar-sided wall. The ulnotriquetral and ulnolunate ligaments along the volar wall of the TFCC have been shown to extend distally from the volar margin of the triangular fibrocartilage and the volar radioulnar ligament, rather than from the ulna itself.^2,3 This confluence of many ligaments on the ulnar aspect of the wrist stabilizes the ulnar carpus to the triangular fibrocartilage as the radius rotates around the ulna.

The blood supply and innervation of the triangular fibrocartilage enters from the periphery.^4,5 Thiru et al. evaluated the vascular perforators to the TFCC in a cadaveric study.⁶ The ulnar artery provides the blood supply to the ulnar portion of the TFCC through dorsal and palmar radiocarpal branches. This ulnar periphery of TFCC has the richest blood supply and the best potential for healing after repair. The dorsal and palmar branches of the anterior interosseous artery supply the more radial periphery and the attachment to the distal radius. The central portion of the TFCC is essentially avascular and is not amenable for repair. Similarly, the radial/central portion has been shown to have essentially no innervation.⁷ The majority of nerve supply to the TFCC is also peripheral, with contributions from the posterior interosseous nerve, the ulnar nerve, and the dorsal sensory branch of the ulnar nerve (DSBUN).

The volar and dorsal radioulnar ligaments are the primary stabilizers of the distal radioulnar joint (DRUJ) during rotation and translation at the DRUJ. As the forearm supinates from a position of full pronation, the volar radioulnar ligament is under stress and lengthens in a viscoelastic manner to accommodate.^8,9 Pronation, from a position of full supination, causes the dorsal radioulnar ligament to be stressed and subsequently lengthen.^8,9 A majority of the load from the carpus are directed to the radius (80%), whereas the remainder (20%) is directed to the ulna through the TFCC.¹⁰

There continues to be dispute among authors as to the advantages of either arthroscopic or open surgery for tears of the TFCC. Significant DRUJ instability has been demonstrated with complete release of the foveal attachments of the TFCC.^11,12 In one study, the DRUJ instability was corrected with an open suture repair of the volar and dorsal radioulnar ligaments through bone tunnels to the fovea or an open version of the arthroscopic repair of the ulnar TFCC to the ECU subsheath.¹² Biomechanical testing demonstrated significant improvements in the stability of the DRUJ for both groups. However, it was noted that the weakest aspect of each repair was not the type of repair but the bioabsorbable polydioxanone suture used.

Patient Presentation

Isolated injuries to the TFCC commonly occur with extension and pronation of the axially loaded carpus, as with falling on an outstretched hand. Activities involving rapid twisting of the hand in relationship to the forearm with ulnar-sided loading (as in racquet sports or golf) may cause subluxation, dislocation, or fracture of the structures of the distal radioulnar joint and the TFCC. Patients often delay treatment or are misdiagnosed as having a “wrist sprain” that fails to get better. Symptoms of TFCC injury include ulnar-sided wrist pain characterized by a diffuse and sometimes burning deep ache that can radiate dorsally or volarly. A clicking sensation in the wrist may be experienced by the patient as the forearm is rotated and the wrist is held in ulnar deviation, as when using a key to unlock a door.

Upon physical examination, acute TFCC injuries present with ulnar-sided wrist swelling. Point tenderness occurs when palpating the ulnar side of the wrist in the ballotable region between the ulnar styloid and the triquetrum. Forearm rotation with the wrist maintained in ulnar deviation may also elicit pain or a wrist click. The TFCC compression test is positive if axial loading of the ulnar side of the hand with ulnar deviation of the wrist results in significant pain. Similarly, de Araujo et al.¹³ described an ulnar impaction test that elicits pain by wrist hyperextension and ulnar deviation with axial compression. Although radiographs may not directly diagnose soft-tissue pathology in cases of suspected TFCC tears without carpal or distal radioulnar joint instability, indirect information can be obtained from the ulnar variance, the distal radioulnar joint congruency, and the presence or absence of a prior ulnar styloid or distal radius fracture.

Magnetic resonance imaging (MRI) with intra-articular gadolinium has become the imaging modality of choice for the diagnosis of soft-tissue injuries, and TFCC injuries are no exception (Figures 5.4 and 5.5). Although an MRI arthrogram may be both sensitive and specific in diagnosing a tear,¹⁴ at this point it has not been shown to be accurate in assessing tear size. In one study, Fulcher and Poehling felt that MRI understaged some TFCC pathology and overstaged others.¹⁵ Pederzini et al. performed arthrography, MRI, and arthroscopy on 11 patients with TFCC injuries.¹⁶ Although these authors found 100% specificities with sensitivities of 80 and 82% for arthrography and MRI (respectively), arthroscopic visualization of a TFCC tear continues to be the gold standard for definitive diagnosis.

FIGURE 5.4 This coronal MRI demonstrates a normal peripheral attachment of the TFCC.

FIGURE 5.5 Here, the coronal MRI shows a tear or disruption of the peripheral TFCC at its ulnar and distal attachment, just proximal to the articular base of the triquetrum.

Classification of TFCC Injuries

Anatomic, clinical, and biomechanical investigations have led to a classification of the triangular fibrocartilage complex injuries. Originally proposed by Palmer,¹⁷ this classification helps differentiate between traumatic and degenerative lesions. Repairable peripheral tears are generally classified as either type 1B or type 1C tears. Type 1B lesions are peripheral tears that occur as the ulnar side of the TFCC complex is avulsed from its capsule ulnar ligamentous attachments. These injuries are amenable to arthroscopic repair of the TFCC if there is no associated ulnar styloid fracture and no associated DRUJ instability. The type 1C injury involves rupture along the volar attachment of the TFCC or tears of the ulnocarpal ligaments. Type 1C tears may be amenable to repair if the ligamentous injury is vertically oriented. Arthroscopic repair of transverse or horizontally oriented tears of the ulnocarpal ligaments has not yet been described to our knowledge.

TFCC tears can be subdivided further by their time course from injury to treatment (Table 5.1).¹⁸ Tears are classified as acute when treated within three months from the time of injury. Arthroscopic repairs of acute tears can result in the recovery of up to 85% of the contralateral grip strength and range of motion.¹⁸ Acute injuries have a better prognosis than subacute injuries and chronic injuries.¹⁹ Subacute tears are treated from three months to one year after injury. Although subacute tears are still amenable to direct repair, in general they tend to regain less strength and range of motion than patients with repair of acute injuries.¹⁹ Chronic tears (more than one year) are repairable, but the results are inconsistent—presumably due to contraction of TFCC ligaments and degeneration of the torn fibrocartilage margins. Chronic injuries frequently require ulnar shortening osteotomy with or without TFCC debridement to decrease the load distributed to the ulna via the TFCC.

Table 5.1 Classification of TFCC Injuries