RATIONALE AND BASIC SCIENCE PERTINENT TO THE PROCEDURE

Injury to the triangular fibrocartilage complex (TFCC) is a common cause of ulnar-sided pain and disability in the wrist.

In 1989, Palmer proposed a classification system for disorders of the TFCC that considers two basic categories: traumatic (class 1) and degenerative (class 2) ( Table 54-1 ). These classes are further subdivided into types, depending on the location of the tear and the presence or absence of associated chondromalacic changes. Class 1 traumatic lesions are subdivided into four types according to the tear’s location. Type 1B injuries are peripheral tears located on the ulnar side of the TFCC. Recent advances in histology and functional anatomy show that the ulnar side of the TFCC is arranged in a complex tri-dimensional structure.

According to structure and function, the TFCC is separated into three components: the proximal triangular ligament, the distal hammock structure, and the ulnar collateral ligament (UCL). Some authors debate the existence of the UCL or consider it to be a part of the floor of the extensor carpi ulnaris (ECU) sheath, eventually including some surrounding loose ligamentous tissue. However, the functional UCL can be assimilated to the distal hammock structure, since they both share the same function of supporting and suspending the ulnar carpus. The distal hammock structure and the UCL should be considered as the distal component of the TFCC (dc-TFCC), which is the opposite of the proximal component (pc-TFCC), represented by the proximal triangular ligament ( Fig. 54-1 ). The proximal triangular ligament is a strong ligamentous structure that originates from the fovea ulnaris and spans to the ulnar corners of the distal radius with two limbs—volar and dorsal. It should be considered the true radioulnar ligament that stabilizes the distal radioulnar joint (DRUJ).

Coronal slice of the ulnar wrist at the level of the fovea . The triangular fibrocartilage complex (TFCC) is outlined. It is separated into the distal component of the TFCC (D), formed by the ulnar collateral ligament and the distal hammock structure, and the proximal component (P), represented by the proximal triangular ligament, which originates from the ulnar fovea and the styloid.

(From Atzei A. New trends in arthroscopic management of type 1-B TFCC injuries with DRUJ instability. J Hand Surg [Eur] 2009; Epub ahead of print.)

Because of the intensity and direction of the traumatic force, either the dc-TFCC or the pc-TFCC or both may be torn. Therefore, ulnar-sided pain, reduced grip strength, decreased forearm rotation, and clinical signs of DRUJ instability may be present accordingly.

Appropriate management of peripheral tears should aim at restoring the original anatomy by direct suture or osseous reattachment of the TFCC by open or arthroscopic repair.

Many arthroscopic techniques have been proposed that suture the torn TFCC to the dorsal ulnocarpal joint capsule and the ECU tendon subsheath. These techniques restore TFCC tautness and thus improve the patient’s symptoms. However, arthroscopic suture is of limited benefit when TFCC tears involve the pc-TFCC and when the DRUJ is clinically unstable. In these instances, an arthroscopic repair is unable to reconstitute the preinjury anatomy and provide adequate joint stability. Therefore, open repair is generally recommended, since it is the only technique that allows for a direct reattachment of the proximal component of the TFCC to its foveal insertion. However, a careful and rather extensive exposure of the distal radioulnocarpal joint is required to perform a TFCC reattachment via either transosseous sutures passed through drill holes or bone anchors.

Continuous advances in the understanding of the intra-articular anatomy and the kinematics of the wrist, as well as the introduction of new volar portals, have contributed to the emergence of an “all-arthroscopic” attitude toward ulnar-sided disorders of the wrist for many surgeons.

This chapter describes a method of an arthroscopic-assisted foveal reattachment using a only devised DRUJ working portal—the direct foveal (DF) portal—which is indicated for repairable proximal or complete peripheral TFCC tears associated with DRUJ instability, but without secondary degenerative changes.

CLINICAL CONSIDERATIONS

The typical candidate for an arthroscopic TFCC foveal reattachment is a patient complaining of ulnar-sided wrist pain, usually after a fall on an outstretched hand or a violent traction and twisting injury of the wrist or forearm.

Patients may complain that their wrist spontaneously “gives way” when they are trying to open a bottle, rotate a steering wheel, turn a door handle, or hold an object in their hand during forearm rotation. The suspected diagnosis is achieved by means of special provocative maneuvers and diagnostic tests. Pain is exacerbated by passive forearm rotation and may be associated with the presence of a click or crepitus or an intra-articular grinding sensation. Resistance rotational movements are often weak and reproduce the patient’s complaints. The ulnar foveal sign is positive; that is, the patient has point tenderness over the ulnar capsule just volar to the ECU tendon. Provided that the forearm muscles are relaxed, provocative maneuvers for DRUJ instability show greater laxity in the painful wrist compared with the opposite side. Hypertonicity of the muscular stabilizers of the DRUJ may lead to false-negative findings; hence it is recommended that DRUJ stability should be evaluated under regional anesthesia before the operation.

Although all patients presenting with acute or chronic wrist pain should have radiographs taken of the wrist, these are usually of limited help in diagnosing isolated TFCC tears, but they may reveal an associated ulnar styloid fracture or nonunion. Still, the usefulness of magnetic resonance imaging (MRI), even with intra-articular gadolinium, is a controversial issue. Whereas an MRI arthrogram may be both sensitive and specific in diagnosing a tear, it has not shown similar accuracy in assessing tear size and location. Studies comparing specificity and sensitivity of arthrography, MRI, and arthroscopy confirm arthroscopic visualization of a TFCC tear to be the gold standard for definitive diagnosis.

Arthroscopy of the radiocarpal joint (RC-Arth) and the DRUJ (DRU-Arth) allows for a thorough evaluation of the tear’s characteristics. RC-Arth is used to evaluate the dc-TFCC. The tear is visualized in the dorsoulnar corner of the TFCC. The TFCC tension is evaluated by the trampoline test and the hook test. The trampoline test evaluates the TFCC resilience (trampoline effect) by applying a compressive load across it with the probe. The test is positive when there is a peripheral TFCC tear, since the TFCC becomes soft and compliant. The hook test consists of applying traction to the ulnarmost border of the TFCC with the probe inserted through the 4-5 or 6R portal. The test is positive when the TFCC can be pulled upward and radially toward the center of the radiocarpal joint ( Fig. 54-2 ). It is a useful maneuver for detecting a foveal disruption of the pc-TFCC.

The hook test . A, In a left wrist, the probe is inserted via the 6R portal through the triangular fibrocartilage complex (TFCC) tear. Traction is applied to the ulnarmost border of the TFCC. B, The test result is considered positive when the TFCC (outlined by the dotted line) can be pulled upward and radially as the pc-TFCC is interrupted or avulsed from the fovea.

(From Atzei A, Rizzo A, Luchetti R, Fairplay T: Arthroscopic foveal repair of triangular fibrocartilage complex peripheral lesion with distal radioulnar joint instability. Tech Hand Up Extrem Surg 2008;12:226–235.)

DRU-Arth is the only method for detecting any ligamentous laceration of the pc-TFCC or avulsion of the foveal attachments. It is mandatory when a hook test yields positive results or when the TFCC tear is associated with clinical signs of DRUJ instability.

Because the DRUJ is a very narrow and tight joint, it may be difficult to perform DRU-Arth when the pc-TFCC is still intact. However, when the pc-TFCC is torn, the articular disk is loose, and more space is available for DRUJ exploration. An 18-gauge hypodermic needle may be placed percutaneously 1 cm proximal to the 6U portal. It will enter the joint close to the fovea and may be used to lift the articular disk—thus enlarging the visual field—and to palpate the pc-TFCC. Furthermore, DRU-Arth allows DRUJ cartilage to be examined for chondromalacic changes.

RC-Arth and DRU-Arth provide a combination of findings that should be considered when deciding on the appropriate treatment of a TFCC tear. They are summarized in the following four parameters.22