Introduction

Injuries to the ulnar side of the wrist may be difficult to diagnose and to treat. Ulnar-sided wrist pain can occur from acute injuries, such as rotation and hyperextension, or from repetitive injuries. These injuries can result in tears of the lunotriquetral interosseous ligament (LTIOL), triangular fibrocartilage complex (TFCC), the palmar ulnocarpal ligaments, or a combination of these structures. Lunotriquetral (LT) joint injuries often exist with associated pathologic conditions such as TFCC injuries and may represent a continuum of injury severity involving the ulnar-sided wrist structures.

Arthroscopy of the wrist has been promoted as an important adjunct to the diagnosis of subtle ligamentous instability because of the ability to directly view the interosseous ligaments, secondary articular cartilage changes, and intra-articular pathology.¹ With the development of advanced techniques and improved instrumentation, wrist arthroscopy is also becoming an important tool in the treatment of complex injuries (including carpal instability).

Normal lunotriquetral kinematics are dependent on the integrity of the lunotriquetral interosseous ligament, ulnolunate ligament (UL), ulnotriquetral ligament (UT), and the dorsal radiocarpal and scaphotriquetral ligaments. The LTIOL is thick both palmarly and dorsally, with a membranous proximal portion. Injury to the LTIOL results in instability between the lunate and triquetrum.

History and Physical Exam

The initial evaluation of the wrist begins with the patient’s history, specifically reviewing mechanism of injury, hand dominance, athletic participation, work history, and recent activities. Areas of swelling, tenderness, and crepitation should be identified. Ballottement or shuck testing is often helpful in diagnosing intercarpal instability.² To perform this maneuver, stabilize the lunate or triquetrum and feel for increased motion of the LT joint during palmar and dorsal stressing. Important physical findings are tenderness over the LT joint and/or the TFCC, increased translation of the lunate with respect to the triquetrum, and crepitation with pain during pronation, supination, or ulnar deviation.

Radiographic evaluation of a painful wrist should include a zero rotation posteroanterior,^3,⁴ true lateral, and oblique views of the wrist. Ulnar variance, lunotriquetral interval, greater and lesser arc continuity, and the radiolunate and scapholunate angles are assessed. In cases where the physical examination findings are equivocal, an arthrogram or MRI can be obtained.

Ulnar Ligamentous Anatomy

Our approach to LT injuries had evolved from the anatomical concepts of the ulnar ligaments in relationship to the lunotriquetral joint and the TFCC. The lunotriquetral interosseous ligament is thicker both volarly and dorsally ⁵ with a membranous central portion. Normal lunotriquetral kinematics is imparted from the integrity of the LTIOL,⁶ ulnolunate, ulnotriquetral,⁶^–⁸ dorsal radiotriquetral (RT), and scaphotriquetral (ST) ligaments.^6,^7,⁹ Severe instability such as a volar intercalated segmental instability (VISI) requires damage to both the dorsal RT and ST ligaments.^6,^7,⁹

The TFCC is the primary stabilizer of the distal radioulnar joint via the dorsal and volar radioulnar ligaments.^10,¹¹ This helps to stabilize the ulnar carpus, and transmits axial forces to the ulna.^12,¹³ The TFCC originates from the ulnar aspect of the lunate fossa of the radius and inserts on the base of the ulnar styloid and distally on the lunate, triquetrum, hamate, and fifth metacarpal base. The integrity of the triangular fibrocartilage, volar radiocarpal, and dorsal radiocarpal ligaments is visible at arthroscopy. TFCC compromise is often a part of more extensive ulnar-sided injuries.¹⁴ The volar and dorsal aspects of the lunotriquetral ligament merge with the ulnocarpal extrinsic ligaments volarly and the dorsal radiolunotriquetral ligament dorsally, anchoring the triquetrum.¹⁵

The ulnocarpal volar ligaments are composed of the ulnolunate (also known as the disc-lunate), the ulnotriquetral (UT)—also known as the disc-triquetral ligaments—and the ulno-capitate. The ulnolunate and ulnotriquetral ligaments originate on the volar triangular fibrocartilage complex (TFCC) and insert on the volar lunate and volar triquetrum (respectively) as well as the LT ligament.^14,^16,¹⁷ Just palmar lies the ulno-capitate ligament, providing a direct attachment from the ulna to the palmar ulnar ligamentous complex.

The arthroscopic approach to symptomatic LT instability is based on the contributing factors of the ulnar carpal ligaments to lunotriquetral joint stability. Suture plication of the ulnar ligaments serves to shorten the disc-carpal ligaments and augment the palmar capsular tissue as part of the arthroscopic reduction and internal fixation.

Ligament plication has been implemented to manage capitolunate instability.¹⁸ The central portion of the volar radiocapitate ligament was tethered to the radiotriquetral ligament by a volar approach. UT-UL ligament plication, developed by one of the authors (FHS), mimics this technique. It has been used in treating those injuries that do not severely destabilize the LT joint, such as those producing a VISI deformity that requires functional compromise of the dorsal extrinsic ligaments (dorsal radiotriquetral and scaphotriquetral). Arthroscopic volar ulnar ligament plication both reduces surgical trauma and allows concurrent assessment of its effect while viewing through the radiocarpal and midcarpal joints.