Triangular fibrocartilage tears

Relevant anatomy and biomechanics

The triangular fibrocartilage complex (TFCC) has been well described. It consists of the articular disk, the meniscus homologue, the palmar radioulnar ligament (PRUL) and dorsal radioulnar ligaments (DRUL), the extensor carpi ulnaris subsheath (ECUS), the ulnar capsule, and the ulnolunate and ulnotriquetral ligaments. The PRUL and DRUL contain a superficial portion and a deep portion that are conjoined at the radius attachment. The superficial portion surrounds the articular disk but has no clear definable insertion into the ulnar styloid. The fibers of the deep portion of the DRUL and the PRUL along with the ulnocapitate ligament interdigitate to form a conjoined tendon as they converge toward their insertion into the fovea at the base of the ulnar styloid ( Fig. 3.1 A–B). Although Kauer noted that Henle and Fick originally designated the ligamentum subcruentum as a vascularized fissure between the ulnar styloid and the deep foveal fibers, Kleinman has suggested that this term now refers to the deep fibers themselves. The deep foveal fibers have a greater effect on rotational stability than the superficial fibers and may be a cause of distal radioulnar joint (DRUJ) instability if detached.

The dorsal and palmar branches of the anterior interosseous artery supply the radial periphery of the TFCC and the attachment to the distal radius. Dorsal and palmar branches of the ulnar artery supply the ulnar styloid and the ulnar aspect of the volar periphery. The peripheral 20% of the ulnar aspect of the TFCC has the richest blood supply and the best potential for healing after repair. The central portion of the TFCC is relatively avascular and therefore is typically not repaired. Synovial nutrition may play a role, however. In a clinical study of ulnar shortening osteotomy (USO) for ulnar impaction, Tatebe et al. showed that 10 out of 13 central TFCC tears were healed at second-look arthroscopy following a USO. The radial and central portions have been shown to have minimal innervation. The majority of nerve supply to the TFCC is peripheral with contributions from the posterior interosseous nerve, the ulnar nerve, and the dorsal sensory branch of the ulnar nerve.

Mechanism and classification

TFCC injuries may occur when the wrist is axially loaded in extension with carpal pronation, which occurs with a fall onto an outstretched hand, from a forceful rotational injury, or from a distraction force. Activities involving rapid twisting of the hand in relation to the forearm with ulnar-sided loading, such as in racquet sports or golf, can also injure the TFCC. Palmer classified traumatic TFCC tears into four categories. A type IA lesion represents an isolated tear in the central portion of the articular disk ( Fig. 3.2 A–B). Type 1B lesions represent a peripheral TFCC tear ( Fig. 3.3 ). Type 1C lesions represent a disruption of the TFCC from the volar ulnocarpal extrinsic ligaments and may result in a supination deformity of the carpus on the ulna ( Fig. 3.4 ). Type 1D lesions represent avulsions of the TFCC from its radial attachment on the sigmoid notch and they are often seen with distal radial fractures ( Fig. 3.5 ). This classification is in wide use and provides guidelines for treatment, but since its publication it has become evident that many types of tears cannot be categorized under this classification.

Abe et al. examined traumatic TFCC tears in 173 wrists and subdivided the disk tears into four types: slit tear, flap tear, horizontal tear, and a tear within the distal radioulnar joint. The researchers subdivided peripheral tears into six types: ulnocarpal ligament tear, dorsal tear, radial tear, ulnar styloid tear, foveal tear, and distal radioulnar ligament tear. Combinations of these types were found in 32 wrists. Longitudinal split tears of the ulnotriquetral (UT) ligament as described by Tay et al. may represent a subtype of the IC tear.

Diagnosis and nonoperative treatment

Patients typically present with ulnar-sided wrist pain and sometimes clicking that is exacerbated by ulnar deviation and by forceful forearm rotation. Patients with a peripheral tear may be tender over the ulnar fovea, which is the soft spot on the ulnar capsule between the flexor carpi ulnaris tendon and the extensor carpi ulnaris tendon. Berger noted that tenderness over the fovea has a sensitivity of 95% and specificity of 86% in detecting foveal disruptions and/or longitudinal split tears of the UT ligament. Patients may have a positive TFCC compression test, which consists of pain with axial loading and ulnar deviation. DRUJ stability should be tested with the forearm in pronation and supination, and the ulnar head should be checked for a positive press test ( Video 3-1 ). In this test the patients place their hand flat on a table in pronation and then push down. In a positive test the ulnar head moves volarly in relation to the radius, which produces a sulcus between the radius and ulna ( Fig. 3.6 A–B). An associated lunotriquetral interosseous ligament (LTIL) tear may demonstrate localized tenderness and a positive lunotriquetral shear test. Extensor carpi ulnaris (ECU) subluxation should be ruled out.

All patients should have AP and lateral x-ray views, including a pronated grip view, to determine ulnar variance. Because the radius rotates around the ulna in pronation, this shortens the radius with respect to the ulna by up to 1.25 cm, hence an ulnar-negative wrist may become ulnar positive with the wrist in pronation, which is the position where ulnar impaction occurs. MR arthrography does not significantly improve the ability to evaluate the central disk of the TFCC, with reported sensitivities of 74% and specificity of 80%. CT arthrography is highly sensitive for detecting central TFCC tears but is not accurate for peripheral tears. A recent metaanalysis of 21 published studies, which included a total of 982 wrists, concluded that MRA was superior to MRI with a pooled sensitivity of 0.75 compared with 0.84 and a pooled specificity of 0.81 compared with 0.95. Most acute tears heal or become asymptomatic with wrist immobilization for 4 to 6 weeks. Activity modification is the hallmark of nonoperative treatment for up to 3 months. Ulnocarpal cortisone injections may be of use in subacute cases. Arthroscopy, however, remains the gold standard in both the diagnosis and treatment of TFCC tears.

Indications for arthroscopy

Arthroscopy is indicated in patients who have failed 3 months of nonoperative treatment unless there is associated DRUJ instability, which should be treated immediately. The site of the lesion is then defined to differentiate between a radial-sided tear, central tear, or a peripheral tear. If the ulnar head is visible, this indicates either a radial tear or central tear. The ulnar head is usually still covered with a peripheral tear. Repairable peripheral tears of the TFCC are either Type 1B lesions or Type 1C lesions. Symptomatic radial TFCC tears with a stable DRUJ may be treated with arthroscopic debridement alone whereas those that are associated with DRUJ instability are repaired.

Contraindications for arthroscopy

Gross DRUJ instability, an arthritic radiocarpal joint, and ulnocarpal abutment preclude repair. Preoperative arthroscopy may still be of benefit in guiding the subsequent open treatment.