Wrist and hand

Arthroscopic portals

The arthroscopic portals are for access to the radiocarpal and mid-carpal joints. The radiocarpal portals are 3–4, 4–5 and 5 ulnar (5U), and 6 radial (6R) ( Fig. 41.1 ). Although a 6 ulnar (6U) portal has been used, it is not recommended because of the proximity of the superficial sensory branch of the ulnar nerve and therefore it will not be discussed. For the mid-carpal joints there are radial and ulnar mid-carpal portals.

Dorsal midline incision

The dorsal midline incision is the ‘work horse’ approach to the wrist ( Fig. 41.2A ). Some surgeons use this incision almost exclusively, although dorso-ulnar and dorsoradial incisions can also be used (see below). The skin incision runs in the midline of the wrist, typically 5–10 mm ulnar to Lister's tubercle. Some variation is allowed to access specific parts of the wrist joint. It is an extensile approach that can be extended up to the metacarpal heads: for example, for extensor tendon transfers, or proximally in the forearm. One of its advantages is that it uses a watershed between the dorsal sensory branches of the radial and ulnar nerves and is therefore safer and less likely to damage the terminal branches of the nerves and cause subsequent painful neuromas.

There are usually one or two large veins deep to the skin that cross the midline and require ligation. Deep to the veins, the extensor retinaculum runs across the whole width of the dorsum of the wrist. Various approaches can be taken. A longitudinal incision through the retinaculum is now less favoured. A zig-zag incision through the retinaculum is a recognized technique, as is an oblique incision in the line of the tendon of extensor digiti minimi, which is preferable to a true longitudinal incision. The retinaculum is raised from ulnar to radial ( Fig. 41.2B ), dividing the vertical septa that separate the compartments. It is important to identify the tendon of extensor pollicis longus (EPL) at Lister's tubercle and to preserve it. It does not necessarily need to be lifted from its tunnel, particularly in the distal half; in theory, leaving it there improves the line of pull of the tendon. Even if the EPL tendon rides out to the radial side of Lister's tubercle, this does not typically cause a functional problem ( Fig. 41.2C,D ).

The capsule of the wrist may be opened using the Mayo approach ( Fig. 41.3 ). This is a ligament-sparing approach from the proximal radius to the triquetrum or just beyond, and then distal radial towards the trapezoid, creating a V-shaped flap with the base to the radial side. Variants of this are used. The capsule can be elevated from the distal radius in continuity with the periosteum but should subsequently be repaired. The radiocarpal and mid-carpal joints are then exposed. It is easy to get lost in the wrist and in particular to mistake the proximal pole of the capitate for the proximal pole of the lunate. Their shapes are different and careful observation of other articulating bones, as well as longitudinal traction, will aid their correct identification. When closing, the capsule and retinaculum are repaired separately with absorbable or non-absorbable sutures.

Dorso-ulnar approach

The dorso-ulnar approach is a longitudinal extensile incision that curves around the radial side of the ulnar styloid to avoid damage to the superficial sensory branch of the ulnar nerve. This nerve is very intolerant of injury, which often results in a painful neuroma. It should be identified if operating within 2–3 cm of the ulnar styloid or palmar to the midline. With the forearm in neutral the superficial sensory branch of the ulnar nerve runs truly mid-lateral, i.e. over the ulnar styloid. Depending on exactly what access is needed, the incision can be dorso-ulnar or even truly mid-ulnar, centred on the ulnar styloid in a line running proximally towards the tip of the olecranon. It is important to note that the skin of the forearm rotates quite significantly relative to the forearm bones. Thus an incision that is longitudinal in one position of the forearm will be rather more oblique in another ( Fig. 41.4 ).

Deep to the superficial sensory branch of the ulnar nerve is the extensor retinaculum, lying over the sixth dorsal compartment. It continues ulnarwards and merges with the flexor retinaculum at the ulnar border of the forearm; the retinaculum is adherent to the subcutaneous (ulnar) border of the ulna. Approaches to the ulnar side of the joint and ulnar head can be longitudinal, overlying the tendon of extensor carpi ulnaris (ECU), retracting it either way, or with a more radial-based flap elevating the ECU tendon. The line of the incision will usually run between the fifth and sixth dorsal compartments. Below it are the capsule of the wrist and the attachments of the triangulo-fibro-cartilaginous complex (TFCC).

De Quervain's/dorsoradial approach (De Quervain's/snuffbox approach)

This incision can be longitudinal, transverse or a little oblique and is centred on, or proximal to, the radial styloid, which is palpable at the proximal palmar end of the anatomical snuffbox.

Deep to the skin is a layer of subcutaneous fat, beneath which runs the superficial sensory branch of the radial nerve. The nerve fans out from approximately 3 cm proximal to the wrist crease, and runs over the tendon of brachioradialis and the first dorsal compartment, which contains the tendons of abductor pollicis longus (APL) and extensor pollicis brevis (EPB). Almost any approach in this area will risk injury to this nerve, and it should therefore be formally identified and protected; injury will often produce a painful neuroma. Deep to the nerve are the tendons of the first and second dorsal compartments, the latter containing the tendons of extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB), and, more distally, the EPL tendon. Below them is the radial capsule of the wrist, which is typically opened longitudinally but can be opened transversely or obliquely, depending on surgical need. The dorsal branch of the radial artery runs obliquely from proximal radial to distal ulnar in the distal end of the anatomical snuffbox. Division is not usually problematic but should be avoided. The artery may sometimes be of use for revascularization procedures and so ideally it should be preserved.

Palmar radial incision

This is another extensile approach through a longitudinal incision based on the tendon of flexor carpi radialis (FCR). A small T-extension distally, about 1 cm in width at the level of the wrist crease, can be quite useful to avoid tension on the wound for approaches at the distal end of the distal radius. The key structure to preserve is the superficial sensory branch of the median nerve. It is easy to make the longitudinal incision a little too ulnar and, with an aggressive skin incision, cut through the nerve before it is identified. It is better to err on the radial side, aiming then to dissect longitudinally down the radial side of the FCR tendon. A little further radially is the radial artery and its venae comitantes but this is quite large and should be easy to identify. The incision can be extended distally and is typically slightly curved in the line of the scaphoid to approach the palmar side of the scaphoid. Having made a careful skin incision, it is sensible to use blunt dissection down to the FCR tendon, clearly identifying the tendon and thereafter incising deep to it through the radial side of the tendon sheath. Distal to this are the muscles of the thenar eminence. The fascia can be incised in the line of the muscles, which run obliquely from proximal ulnar to distal radial about 30° to the long axis, and then dissected bluntly to avoid damage to the muscle fibres themselves. The approach is developed through the centre of the bed of the FCR tendon sheath, down to the radius. If the dissection is intended only to expose the distal radius, it is important not to extend the approach too far distally and risk damage to the palmar radial carpal ligaments, which may result in stiffness. To gain access to the scaphoid, these ligaments are usually divided, but if the scaphoid fracture is either in the mid waist or distal, then it is normally possible to keep some of the proximal parts of the palmar radial ligaments, particularly the radio-scapho-lunate ligament, which may give better stability and less stiffness in the long term.

Deep to the tendon bed of FCR is the tendon of flexor pollicis longus (FPL), which is identified by its muscle running to the level of the wrist joint and by flexing of the thumb. This tendon is retracted radially, further protecting the radial artery. A self-retaining retractor must be carefully positioned and gently applied because overzealous use can cause damage to the median nerve. Deep to this is pronator quadratus; it may be possible to retract the muscle and to apply a plate to the radius beneath it, or just elevate its most distal part. Often, the whole of pronator quadratus is elevated as an ulnar-based flap. It is incised distally at the level of the watershed line of the distal radius and then along the radial border of the distal radius. It is next raised off the bone with a periosteal elevator. Reattachment is often futile and has not been shown reliably to improve outcomes. Only a limited closure is necessary, with repair of the capsule over the scaphoid and the distal bed of the FCR tendon.

Palmar midline incision

This approach can be used for extension of a carpal tunnel release or for approaches to the flexor compartment in the distal forearm. This is a midline incision: that is, midway between the radial and ulnar styloid processes. If the wrist crease is crossed, this should ideally be done in a zig-zag or oblique manner to avoid a longitudinal incision across the flexor crease ( Fig. 41.5 ). The zig-zag need only be 3–4 mm across. Palmaris longus is deep to the skin, if present (it is absent in about 16%), and the median nerve is deep to palmaris longus. Dissection in this area needs to be careful, particularly if palmaris longus is absent. It is important not to go either too deep or too radial. The contents of the carpal tunnel (the digital flexor tendons and the median nerve) run deep to the fascia. Deeper dissection is facilitated by gentle spreading of the tendons to expose pronator quadratus and the radius and ulna. The palmar capsule of the wrist is distal to the radius and ulna. The wrist is not normally opened through this approach, but if it is, then a ligament-sparing incision is recommended. This is essentially transverse but oblique from proximal radial to distal ulnar in the line of the palmar carpal ligaments, similar to the extrinsic ligaments. The only closure needed is of the wrist capsule (if opened) and the skin.

Occasionally, several palmar transverse stab incisions (≤1 cm) are used over palmaris longus in order to harvest it for use as a tendon graft. Blunt dissection is carried out with scissors down to the tendon, which is lifted out through the incisions and identified prior to division.

Palmar ulnar approach

This approach is used to access the palmar/ulnar aspect of the distal radio-ulnar joint (DRUJ). It can be extended to access Guyon's canal by crossing the flexor crease of the wrist with zig-zag or oblique incisions. The key landmark is the pisiform. The incision should start 2–3 mm to the radial side of the bone, going proximal from the wrist crease overlying the line of the DRUJ.

Deep to the incision is the flexor retinaculum and below that is the tendon of flexor carpi ulnaris (FCU); the ulnar neurovascular bundle lies deep and to its radial side. This bundle should be formally identified, protected and mobilized towards the ulnar side to give access to the DRUJ beneath pronator quadratus and the joint capsule. Either pronator quadratus can be retracted proximally or the distal third can be elevated from the distal ulna. Closure is typically of just the joint capsule and skin.