Wrist Arthroscopy

Fig. 1

Arthroscopy tower. This type of tower provides distraction whilst allowing repositioning and wrist orientation as required

The scope used is 2.7-mm calibre oriented at 30°. This scope is adequate for exploration of the radiocarpal and midcarpal joints. The ‘needle’ 1.9-mm scope is only rarely used for exploration of the distal radioulnar joint. The trocar is smooth-tipped to avoid cartilaginous lesions during introduction. It bears the connection for the light source, and the irrigation. Once in place, the light connects to the video camera where the joint is visualized on a monitor screen and not by direct vision. The probe is an indispensable instrument in this set. Its size and the smoothness of its tip must be adapted to the size of the joint explored. A set of two graspers (straight and curved) as well as a single-use knife are useful for debridement of the TFCC when necessary. The use of powered instruments (shavers and burrs) for arthroscopic surgery for the TFCC is quite common practice now [6].

1.3 Access Portals

The portals of access are designated by the corresponding dorsal extensor compartments (Fig. 2). We recommend defining all the portals that will be needed at the beginning of the operation. The development of a ‘hydroma’ due to diffusion of the irrigation fluid renders it difficult to identify bone and tendon landmarks later throughout the course of the procedure. For all portals, a small calibre needle is used for identification. If elastic resistance is encountered at the point of entry, it is easy to reposition the needle to avoid tendons. A hard resistance is characteristic of bone. Correct penetration into the joint interval is denoted by a suction sound due to the intra-articular negative pressure resulting from the distraction. Once the interval is marked by the needle, portal access can be established using an N°15 blade perpendicular to the surface. The scope or probe can then be introduced.

Fig. 2

Portals for exploration of the wrist. The current portals for wrist exploration are identified in relation to the extensor compartments. Portal 3/4 is on the radial border of the extensor communis EDC (1) and portal 4/5 on the ulnar border of EDC (2). Portals for the midcarpal joint are RMC (3) and UMC (4). Portal 6U (5) is commonly used as drainage outlet for the irrigation

To explore the radiocarpal joint, three portals are usually sufficient.

Portal 3/4 is the first point of introduction of the scope. This portal is situated at the radial border of extensor communis tendon. The tubercle of Lister is the bony landmark for this portal. It is found by palpating with the thumb along the posterior border of the radial glenoid.

The depression indicating the joint interval can be palpated about 1 cm above (distal) this point. The needle should be introduced obliquely on account of the radial slope in the sagittal plane. The knife should be held sharp facing downward to avoid iatrogenic lesion of the scapholunate interosseous ligament.

Portal 4/5 is between the EDC and EDM and serves for probe introduction for exploration of the radiocarpal joint. The depression between the two tendons is readily palpable and introduction is more proximal than the previous portal on account of the radial slope in the frontal plane. These portals 3/4 and 4/5 are the least risky for sensory nerve branches [7].

Portal 6U is situated on the ulnar border of the ECU. This is the site for the needle for drainage of the irrigation fluid.

Other portals. The 6U portal is seldom used. It is useful for arthroscopic surgery of the TFCC. Palmar portals are only used for arthroscopically assisted reduction of distal radius fractures. Introduction of the scope through the FCR has been proposed as a secure method of exploring the most palmar portion of the scapholunate ligament [8, 9].

1.3.1 Portals for Exploration of the Midcarpal Joint

The radial midcarpal RMC is situated on the radial border of the EDC, about 1 cm distal to the 3/4 portal (Fig. 2). This corresponds to the scaphocapitate interval more difficult to palpate than the radiocarpal interval. The ulnar midcarpal portal UMC is situated on the ulnar border of EDC about 15 mm from 4/5 and corresponds to the triquetrohamate interval.

2 Performing a Diagnostic Arthroscopy

2.1 Analysis of Radiocarpal Chondral Lesions

Simple inspection of the articular surfaces is followed by probing any cartilage defect or lesion. The topography, extent and severity of the lesion is appreciated and noted. Healthy cartilage feels firm and elastic when palpated using the probe. The probe does not leave an imprint on healthy cartilage, and a full-thickness cartilaginous lesion is hard on probing.

This exposure of subchondral bone is synonymous to arthritis even if the lesion is of limited extent and does not show on X-ray. All other chondral lesions without bone exposure are grouped under the generic term ‘chondritis’. A precise description of the lesion must specify if it is simple cartilage oedema (the cartilage bears the imprint of the probe), a fibrillary chondritis (associated with cartilaginous flaps) or a partial defect not exposing the underlying bone (without arthritis).

2.2 Study of the Radiocarpal Articular Surfaces

Diagnostic arthroscopy begins by visualization of the scaphoid and lunate fossae of the radius, separated by a blunt anteroposterior ridge (Fig. 3). Through the same portal, the scope is oriented ulnar to explore the horizontal portion of the TFCC.

Fig. 3

Exploration of the radiocarpal joint. Scaphoid (S), Scaphoid fossa (fs) and Lunate fossa of the radius (fl) separated by a blunt ridge

The radial insertion, central portion and the anterior border of the TFCC must be systematically palpated as they are often the site of traumatic or degenerative lesions. An intact healthy TFCC gives a firm elastic resistance to probing – described as the ‘trampoline effect’. When pushed to the ulnar side of the radiocarpal interval, the probe may access the prestyloid recess and penetrate it. This is a physiologic extension of the radioscaphoid joint. A radial traction motion must be applied as if to pull the full thickness of the TFCC laterally. This can depict a peripheral (ulnar) disinsertion of the TFCC. If no lesion, the peripheral TFCC insertion stays taut resisting probing and no wave effect is elicited. Examination of the carpal surfaces follows. Scaphoid convexity is examined until the styloscaphoid space and then the lunate dome is inspected. The 3/4 portal does not allow easy access to the triquetrum; thus, the scope must be reintroduced through the 4/5 portal to complete the radiocarpal examination.

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