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INTRODUCTION

Arthroscopy has continued to revolutionize the practice of orthopedic surgery, providing the technical capability to examine and treat intra-articular abnormalities. The wrist is a complex labyrinth of eight carpal bones and multiple articular surfaces combined with multiple intrinsic and extrinsic ligaments, including the triangular fibrocartilage complex (TFCC)—all within a 5-cm interval. This perplexing joint continues to challenge clinicians with an array of potential diagnoses and treatments. Wrist arthroscopy allows direct visualization of the cartilage surfaces, synovial tissue, and ligaments under bright light and magnified conditions. Wrist arthroscopy is a particularly valuable adjunct in the management of disorders of the TFCC.

This chapter reviews the indication for wrist arthroscopy in the management of peripheral ulnar-sided tears of the articular disk involving the TFCC. Several techniques for outside-in and inside-out repair of peripheral ulnar-sided tears of the TFCC have been previously described in the literature. In addition, a new technique that allows arthroscopic-assisted fixation of the articular disk back down to bone with a suture anchor is described here.

The TFCC is a complex soft tissue support system that stabilizes the ulnar side of the wrist. It acts as an extension of the articular surface of the radius to support the proximal carpal row and also stabilizes the distal radioulnar joint. As classically described by Palmer, it is composed of the fibrocartilage articular disk, the volar and dorsal radioulnar ligaments, and the floor of the extensor carpi ulnaris tendon sheath. The central disk is wedge-shaped in the coronal section and radially inserted on the articular surface of the radius by merging with hyaline cartilage of the sigmoid notch and the lunate facet. Chidgey and colleagues evaluated the collagen structure of the TFCC in an attempt to correlate this with biomechanical function. They reported that the radial side of the articular disk fibrocartilage has thick collagen projecting 1 to 2 mm into the disk. The central portion of the articular disk has an oblique wave pattern for strength, compression, and tension, and the ulnar aspect of the articular disk has two main bundles. One bundle is directed to the ulnar styloid and the second bundle to the fovea. Proximal limbs of the palmar and dorsal radioulnar ligaments conjoin and insert into the fovea just medial to the pole of the distal ulna. These structures are referred to as the ligamentum subcutaneum. The distal superficial portions of the volar and dorsal radioulnar ligaments insert directly into the base of the ulnar styloid and are independent of the function of the ligamentum subcutaneum insertion. The exact function of the superficial and deep components of the volar and dorsal radioulnar ligaments is controversial and has been studied by several investigators.

The articular disk is an axial load-bearing structure as defined by Palmer. In the static state, 82% of the axial compressive load of power grasp was transmitted from the forearm through the radiocarpal joint. Approximately 18% is supported by the articular disk in the ulna. The peripheral attachment of the articular disk is almost 5 mm thick and becomes thinner at the radial insertion, narrowing to less than 2 mm. It is the central portion that accepts most of the compressive loads transmitted from the carpus to the ulna. The thickness of the articular disk varies from individual to individual with an inverse relation between the thickness of the articular disk in ulnar variance. When the disk is excised, load bearing by the ulna drops to approximately 5% of the total.

Dorsally, the TFCC has attachments to the ulnar carpus and to the sheath of the extensor carpi ulnaris. This is a common area of peripheral detachment of the articular disk. The floor of the sheath of the extensor carpi ulnaris is thick, stout, fibrous tissue. This stout, fibrous tissue allows for firm suture fixation of the articular disk back to the floor of the sheath of the extensor carpi ulnaris.

The third component of the TFCC is the ulnar carpal meniscus homologue. This is a controversial structure as to its function and existence. It is a layer of fibrous connective tissue with variable thicknesses. The prestyloid recess typically presents between the bony ulnar styloid and the thickening of the ulnar soft tissues known as meniscus homologue. It is vital to understand that the prestyloid recess is a normal fovea and not to be mistaken for a peripheral tear to the articular disk. The prestyloid recess is the site of the 6U portal and is frequently used for inflow.

The ulnar carpal ligaments are composed of the ulnar lunate and ulnar triquetral ligaments. These ligaments are the primary stabilizers of the ulna and palmar carpus. The origin has been shown, by cadaver studies, to be along the palmar margin of the TFCC. The ligaments insert independently on the lunate and the triquetrum with an additional insertion into the lunotriquetral interosseous ligament.

The arterial blood supply of the TFCC has been thoroughly studied. Thiru and colleagues. evaluated 12 cadaveric specimens with latex injections and determined that there are three main arterial supplies to the TFCC. The ulnar artery supplies most of the blood to the TFCC, supporting the ulnar portion through dorsal and palmar radiocarpal branches. Thiru and colleagues documented a complex of vessels filled with latex dye in the peripheral 15% to 20% of the articular disk. Similarly, Bednar and associates examined 10 cadavers with an ink injection and found penetration of the vessels into the peripheral 10% to 40% of the articular disk. These studies are very significant regarding procedures for arthroscopic repair of peripheral tears to the articular disk. They confirm an intact blood supply through the peripheral articular disk, and theoretically peripheral tears of the articular disk should heal following repair.

CLASSIFICATION OF TRIANGULAR FIBROCARTILAGE COMPLEX TEARS

In 1989, Palmer proposed a classification system for tears of the TFCC that divides these injuries into two basic categories: traumatic (class I) and degenerative (class II) ( Table 16-1 ). The Palmer classification determines the course of management for injuries to the TFCC.

Class I injuries are acute traumatic tears that are subdivided into four types based on the zone of injury. Type IA lesions involve a central avascular portion of the articular disk and therefore are not suitable for suture repair. Arthroscopic management is limited to debridement of the central tear to remove any flaps that may be symptomatic. Type IB (ulnar avulsion) injuries occur when the ulnar side of the articular disk is avulsed from its insertion. These injuries may or may not be associated with a fracture of the ulnar styloid. Such tears occur where there is a documented vascular supply, and they are very amenable to arthroscopic repair. Type IC injuries involve rupture of the volar attachment of the TFCC over the ulnar carpal ligaments. Type ID (radial avulsion) tears occur when the radial attachment of the articular disk with involvement of the radioulnar ligaments separates from the radius with or without a fracture of the radial sigmoid notch.

Class II lesions are degenerative tears of the TFCC, and all involve the central portion of the articular disk. These are staged A to E, depending on the presence or absence of perforation to the TFCC, lunate and ulnar chondromalacia, lunotriquetral ligament perforation, and degenerative radiocarpal arthritis. These degenerative lesions usually arise from ulnar impaction, and surgical management decreasing the load to the ulnar-sided wrist is recommended.

DIAGNOSIS

Injuries to the TFCC commonly occur with extension and pronation of the axial-loaded carpus. The most common mechanism occurs with a fall on an outstretched hand. Peripheral tears of the articular disk are common athletic injuries, which involve rapid twisting of the wrist such as the ulnar-sided loading activities of racket sports and golf. Peripheral ulnar-sided tears of the articular disk are also a common work injury. Patients describe a mechanism of traction and twisting of the forearm such as when a drill malfunctions and the patient sustains a twisting injury to the wrist.

Symptoms of peripheral tears of the TFCC include deep infused aching along the ulnar side of the wrist. Patients complain of pain with firm gripping. Patients may complain of a clicking sensation with pronation and supination. They frequently complain of pain while attempting to twist lids off jars or twisting a doorknob. Patients also may complain of generalized weakness of the wrist.

Patients with an ulnar peripheral tear to the articular disk of the TFCC frequently complain of pain at the prestyloid recess. This pain may be accentuated by hyperpronation and supination of the wrist. The pain may be further aggravated by passive anterior and posterior translation of the ulna in relation to the radius with the wrist in pronation and supination. When a large ulnar peripheral tear is present, dorsal subluxation of the ulnar head in relation to the radius may be seen, particularly when compared with the opposite wrist when both the wrists are in pronation and flexion.

Several tests have been described that are helpful in the diagnosis of ulnar-sided wrist pain. The triangular fibrocartilage compression test is positive with axial loading of the articular disk with ulnar deviation resulting in significant pain. de Araujo and colleagues described the ulnar impaction test and list pain with wrist hyperextension, ulnar deviation, and axial compression. The piano key test reveals distal radioulnar joint instability, which can be seen with a peripheral tear of the articular disk if the distal ulna is found to move more freely in the volar-dorsal plane compared with the opposite wrist. In general, patients with a central tear of the articular disk complain of pain more over the ulnar head, whereas patients with a peripheral tear complain of pain more about the prestyloid recess area.

DIAGNOSTIC MODALITIES

Patients who present with acute or chronic ulnar wrist pain should be evaluated with standard anteroposterior, lateral, and oblique radiographs of the wrist. It is important to take the anteroposterior view with the wrist in neutral position to evaluate for ulnar variance. Further x-ray signs of ulnar impaction that include cystic findings of the lunate and distal ulna, particularly in an ulna-positive wrist, imply excessive loading through the ulnar carpus and may require an ulnar-shortening procedure. The distal radioulnar joint should be evaluated for signs of ulnar impingement to be differentiated from pain from the TFCC. In addition, signs of injury—acute or chronic to the ulnar styloid—should be assessed on plain radiographs.

Triple-injection arthrography has been useful in diagnosing pathology in the TFCC. However, ulnar-sided peripheral tears of the articular disk may be missed, particularly in the chronic setting. This is secondary to chronic synovitis that develops over the peripheral tear, which may block the flow of dye between the radiocarpal joint and distal radioulnar joint.

Several studies have evaluated the usefulness of magnetic resonance imaging (MRI) in the diagnosis of triangular fibrocartilage injuries. Golimbu and associates and Skahen and associates noted that MRI detected tears of the central and radial detachment of the articular disk with an accuracy of 95%. Corso and associates, in a study of ulnar-sided tears of the triangular fibrocartilage, found a sensitivity of only 76%. Bednar and associates reported the MRI was 44% sensitive and 75% specific for tears of the triangular fibrocartilage. Fulcher and Poehling felt that MRI overstates some injuries of the triangular fibrocartilage while understating other triangular fibrocartilage pathology and recommended arthroscopy for definitive diagnosis.

Studies comparing arthroscopy with arthrography confirm that arthroscopy is the gold standard in detecting injuries of the TFCC. Pederzini and associates compared arthrography, MRI, and arthroscopy in 11 patients with tears of the TFCC. Using arthroscopy as a gold standard, the researchers reported 100% specificity with MRI and arthrography, 80% sensitivity with arthrography, and 82% sensitivity for MRI evaluation. Arthroscopy has the advantage of clear visualization of the articular disk in bright light and magnified conditions. The tension of the articular disk can be palpated with a probe, and usually with a peripheral tear a loss of tension can be detected. Frequently, reactive synovitis will have formed over a peripheral ulnar-sided tear. When this is debrided out, the peripheral tear is well visualized. Arthroscopy not only has the advantage of diagnosis, but once identified, the tear may be arthroscopically repaired.