Introduction

The anatomy of the wrist is now well known and many anatomical sources describe the components of this complex, functional, and well organized joint. However, arthroscopic anatomy is particular in that the arthroscope provides vision inside the joint; one must learn to analyze the view of the bones and ligaments from inside the wrist joint and mentally visualize the global wrist structure. The first step is to examine diagrams and dissections with the distal end of the wrist at the top of the page, because most arthroscopy procedures are performed with axis translation with the hand in the “American position” (i.e., the fingers pointing toward the ceiling). Another important particularity is that traction creates new anatomical spaces, allowing the arthroscope to enter the wrist ( Figs. 3.1 , 3.2 , 3.3 ).

Principles of Exploration

Traction in the axis of the wrist creates space between the radius and the first carpal row (the radiocarpal space) and between both carpal rows (the midcarpal space). Saline injection can help distend these potential spaces.

Blunt-ended clips are used to enter the joint so as not to injure the noble structures (i.e., nerves, veins, and tendons), using the classic arthroscopic portals.

Radiocarpal Exploration

We usually start through the 3–4 radiocarpal portal and immediately find the scapholunate (SL) ligament—a shiny valley between the two promontories of the lunate and scaphoid ( Figs. 3.4 and 3.5 ). We then push the scope to find the ligament of Testut at the junction between the palmar SL ligament and the anterior capsule of the wrist. The scope is directed laterally, and the lateral distal part of the radiocarpal joint is visualized (i.e., the distal pole of the scaphoid above, and the scaphoid fossa and radial styloid below). The entire convexity of the scaphoid and radial cartilages can be assessed. If the scope is pushed forward, the anterolateral extrinsic ligaments can be seen: the radioscaphocapitate (RSC) ligament and the long radiolunate ligament (LRL) ( Fig. 3.6 ). These ligaments are better seen on arthroscopy than in cadaveric dissection because they are intracapsular and extrasynovial. Their tension can be tested either by moving the wrist in ulnar and radial deviation or by using a probe inserted through the 6R or 4–5 portal. The zone of origin of palmar wrist ganglia lies between these extrinsic ligaments.

The scope is then slid from lateral to medial following the scaphoid convexity to find the SL ligament depression, a concave furrow extending from the cartilages of two bones: the proximal pole of the scaphoid and the proximal aspect of the lunate. The SL ligament can be visualized entirely, from its palmar aspect to its dorsal side. The radioscapholunate ligament of Testut should not be mistaken for pathological synovitis; it can be more or less vascularized ( Fig. 3.7 ). Not a real ligament, it is rather a vessel and proprioceptive nerve carrier for the SL ligament, with no stabilizer role. It is the direct prolongation of the anterior vessels and the anterior interosseous nerve. On the anterior aspect of the carpus, and just medial to the ligament of Testut, lies the short radiolu-nate (SRL) ligament, which is more difficult to see.

By drawing the scope slightly backward, the distal surface of the radius can be assessed, with the scaphoid fossa laterally and the lunate fossa medially separated by a bony ridge related to the SL ligament.

We then move medial to the radiocarpal joint and follow the proximal surface of the lunate. The lunotriquetral ligament can be seen above ( Fig. 3.8 ) as a valley between the lunate laterally and the triquetrum medi-ally. The triquetrum is less often seen through the 3–4 portal, and the ulnocarpal ligament is also difficult to see.

The key to assessing the medial radiocarpal joint is the triangular fibrocartilage complex (TFCC) exploration. The TFCC is a fibrocartilage disk, normally tense, with a medial insertion showing a regular anatomical perforation called the styloid recess ( Fig. 3.9 ). Its peripheral insertions on the palmar and dorsal capsule and on the radius can be assessed, as well as its foveal insertion on the ulnar head ( Figs. 3.10 and 3.11 ). A hook introduced through the dorsal 6R portal can be used to assess all insertions and to test the trampoline effect (the hook should spring briskly back when this ligament is stretched and tensed, and return to normal upon release).

To complete the radiocarpal joint exploration and “see” certain zones, the scope position may be swapped (in the 6R portal) with that of the instruments (in the 3–4 portal). The assessment of the triquetrum, the lunotriquetral ligament, and the lunate is easier in this position. This is the only approach by which to see the dorsal “cul de sac” between the reflection of the dorsal capsule and the first carpal row, especially the attachment of the dorsal portion of the SL ligament to the dorsal capsuloligamentous septum—one of the first zones affected in SL instability ( Figs. 3.12 and 3.13 ).