PREVENTING COMPLICATIONS

Arthroscopy has justifiably been touted as a safe and effective method for examining the intra-articular components of the radiocarpal and midcarpal joints,²⁸ and it is considered a relatively low-risk procedure.^29–33 As with any surgical procedure, complications may be encountered, including tendon injury from inappropriately placed portals, skin slough from traction devices, nerve injury, complex regional pain syndrome,^34–36 and rare conditions such as one case involving fistula formation after wrist arthroscopy.³⁷ Associated with each portal are certain anatomic structures with which the surgeon must be familiar to prevent portal-specific complications from occurring.³⁸ This chapter seeks to familiarize the wrist surgeon with these structures and techniques for preventing injury to them. Portal anatomy and the risks associated with each portal based on surrounding anatomic structures are addressed, along with the general risks associated with wrist arthroscopy. The Pearls and Pitfalls section describes common errors made when learning wrist arthroscopy and the techniques employed to avoid those errors.

One commonly employed technique to facilitate wrist arthroscopy is to place the wrist into traction with slight flexion that distracts the joints, making the portal intervals more easily palpable and allowing easier and less traumatic trocar and cannula entry into the joint. One portal is established to allow visualization during placement of the other portals. Most commonly, it is the 3-4 portal. Insufflation of the joint using lactated Ringer’s solution through an 18-gauge needle placed in the 3-4 portal allows distention of wrist joint capsule. This portal is located just distal to Lister’s tubercle and radial to the extensor digitorum communis at the radiocarpal joint line.

For making portal skin incisions, we recommend using a no. 11 scalpel blade in the longitudinal orientation just into the skin with traction on the skin itself, thereby making a skin incision without the trauma of an in-and-out sawing motion, which places deeper structures at risk.

RISKS AND COMPLICATIONS BY PORTAL SITE

Wrist arthroscopy portals are based on the extensor compartments of the wrist. Figure 36-1 provides an overview of the dorsal arthroscopy portals with associated structures.

FIGURE 36-1 Dorsal arthroscopy portals 3-4, 4-5, and 6-R are safe to use because they are clear of the dorsal sensory nerves.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

1-2 Portal

The structures most at risk by placement and use of the 1-2 portal (i.e., extensor pollicis brevis–extensor carpi radialis longus [EPB-ECRL] portal) are the radial artery and superficial radial nerve. The radial artery lies deep to the first dorsal compartment and therefore should be out of harm’s way if the portal is placed correctly. However, if the portal is placed too radially or too distally, this structure is at risk for injury. The easiest way to avoid damage to the radial artery as it passes deep to the tendons is to make a small portal incision, bluntly dissect down to capsule, and insert the trocar through the capsule after ensuring that the artery is not directly under the trocar.

The superficial radial nerve is also at risk because its dorsal branch lies over the 1-2 portal. The most effective way to avoid laceration or traction of this nerve as the medial branch of the superficial radial nerve arborizes ulnarly is to make the portal skin incision with a no. 11 blade knife inserted only through the skin layer and then by traction on the skin itself, rather than using the blade, to enlarge the portal. Blunt dissection down to the capsule is recommended to ensure preservation of this dorsal branch as it crosses the portal site (Fig. 36-2).

FIGURE 36-2 The 1-2 portal is near to the radial artery and superficial radial nerve.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

3-4 Portal

The structures most at risk during placement of the 3-4 portal (i.e., extensor pollicis longus/extensor carpi radialis brevis–index extensor digitorum communis [EPL/ECRB-index EDC] portal) are the tendons of the EPL, ECRB, and EDC. This portal should be placed just distal to Lister’s tubercle, around which the EPL tendon passes.

The 3-4 portal is most commonly the first portal established and is most easily established by inserting an 18-gauge needle into the wrist joint just distal to Lister’s tubercle and insufflating the joint with as much solution as the joint can hold comfortably. At that point, the needle and syringe may be removed from the joint while maintaining the capsular distention. The information from needle insertion and palpation of the capsular distention guides placement of the 3-4 portal directly over the radiocarpal joint between the ECRB/EPL and the EDC. The skin is pulled over the tip of the blade to establish the portal, lessening the risk of inadvertently lacerating one of the tendons. After the skin incision is made, the blunt trocar and cannula are inserted, moving the tip in a medial and lateral direction to have tactile feedback and ensuring guidance into the joint without injury to the articular cartilage (Fig. 36-3).

FIGURE 36-3 The 3-4 portal provides excellent, safe access to the extensor pollicis longus, extensor carpi radialis brevis, and extensor digitorum communis tendons in the wrist.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

4-5 Portal

The structures most at risk during placement of the 4-5 portal (i.e., extensor digitorum communis–extensor digiti quinti [EDC-EDQ] portal) are the terminal branch of the posterior interosseous nerve and the dorsal sensory branch of the ulnar nerve. The posterior interosseous nerve passes deep to the fourth dorsal compartment on the ulnar side dorsal to the wrist to provide sensation to the wrist joint. The risk of damage to this nerve during placement of the 4-5 portal is lessened by placement of the portal in a slightly ulnar position with relation to the EDC tendon. The portal should be placed just radial to the EDQ tendon. From a practical point of view, the loss of the function of this nerve causes no functional deficit, and some think that it diminishes pain in the wrist joint.

The transverse branch of the ulnar dorsal sensory nerve is also at risk during placement of this portal. The transverse branch of this nerve passes distal to the portal, and risk of injury may be lessened by placing the portal as proximal as possible in the wrist joint. We recommend longitudinal portal placement followed by blunt insertion into the joint to ensure preservation of the nerve (Fig. 36-4).

FIGURE 36-4 The 4-5 interval is close to the terminal branch of the posterior interosseous nerve. Most think this nerve supplies only sensation to the wrist joint itself and is of little consequence if sacrificed.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

6-R Portal

The structures at most risk during placement of the 6-R portal (i.e., radial to the extensor carpi ulnaris [ECU] tendon) are the extensor tendons and branches of the dorsal sensory branch of the ulnar nerve. This nerve passes ulnar to the portal, and we stress portal placement on the radial side of the ECU tendon with blunt dissection to the joint, thereby preventing damage to this superficial nerve. We recommend making the skin incision in a longitudinal fashion with careful dissection down to capsule, at which point the trocar may be safely placed bluntly on the radial side of the ECU tendon (Fig. 36-5).

FIGURE 36-5 The 6-R portal can be used safely as long as it is on the radial side of the extensor carpi ulnaris.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

6-U Portal

The structure at most risk during placement of the 6-U portal (i.e., ulnar to the ECU tendon) is the main dorsal sensory branch of the ulnar nerve. We do not recommend the use of this portal unless there is no other alternative. This nerve passes over the portal, and we stress portal placement with blunt dissection to the joint, thereby preventing damage to this superficial nerve. We recommend making the skin incision and then carefully dissecting down to capsule to ensure that the nerve is not lacerated or entrapped during portal placement. After the nerve has been protected, the trocar may be placed bluntly on the ulnar side of the ECU tendon (Fig. 36-6).

FIGURE 36-6 The 6-U portal is close to the main dorsal sensory branch of the ulnar nerve. If this portal must be used, dissection and retraction of the nerve must be performed before portal placement.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

Midcarpal Radial Portal

The structures most at risk in the midcarpal radial (MCR) portal (i.e., 1 cm distal to the 3-4 portal and in line with the radial border of the long metacarpal) are the extensor tendons (Fig. 36-7) and the articular cartilage. The space available for portal placement is smaller in the MCR portal compared with the midcarpal ulnar (MCU) portal (Fig. 36-8). For smaller patients, we recommend the use of a 1.8-mm arthroscope in all of the portals of the midcarpal joint because of the small potential space.

FIGURE 36-7 The midcarpal radial portal is 1 cm distal to the 3-4 portal and is bordered by the extensor carpi radialis longus and extensor digitorum communis tendons. There are no adjacent nervous or vascular structures.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

FIGURE 36-8 This intra-articular section demonstrates that the articular cartilage is at risk with placement of the midcarpal radial portal because of the small space available for instrumentation.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

Midcarpal Ulnar Portal

The structures most at risk in the MCU portal (i.e., 1 cm distal to the 4-5 radiocarpal portal and in line with the axis of the ring metacarpal) are the extensor tendons (Fig. 36-9) and the articular cartilage. This portal has more room than the MCR portal, especially in patients who have a significant hamate facet of the lunate (Fig. 36-10).

FIGURE 36-9 The midcarpal ulnar portal is 1 cm distal to the 4-5 radiocarpal portal and is bordered by the extensor digitorum communis and extensor carpi ulnaris tendons. There are no adjacent nervous or vascular structures.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

FIGURE 36-10 This intra-articular section demonstrates the relatively larger space in the midcarpal ulnar portal compared with the midcarpal radial portal.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

Scaphotrapeziotrapezoid Portal

The structures most at risk with placement and use of the scaphotrapeziotrapezoid (STT) portal (i.e., EDC-EPL distal portal) are the radial artery and superficial radial nerve. The radial artery passes deep to the extensors through the anatomic snuffbox to lie between the two heads of the first dorsal interosseous muscle, and it is therefore directly at risk during placement of this portal (Fig. 36-11). The easiest way to avoid damage to the radial artery is to approach the space between the ECRL and the ECRB and ulnar to the EPL. This approach ensures that the artery and the radial nerve are palmar and radial to the portal.

FIGURE 36-11 The structures most at risk during placement and use of the scaphotrapeziotrapezoid (STT) portal are the radial artery and superficial radial nerve. It is safest if the STT portal is made on the radial border of the extensor carpi radialis brevis tendon.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

Palmar Portal

The palmar portal is the most precarious of all the portals discussed, because it lies between the radial artery, the median nerve, and the palmar cutaneous nerve (Fig. 36-12). Whether placed inside-out or outside-in, care must be taken to preserve the radial artery, which lies radial to the flexor carpi radialis (FCR) tendon; the palmar cutaneous nerve, which lies superficially between the FCR and palmaris longus tendons; and the median nerve, which lies deep to the palmaris longus and ulnar to the FCR. If placing the portal with an inside-out technique, the switching stick should be placed through the 3-4 portal between the radioscaphocapitate ligament and the long radiolunate ligaments with an incision radial to the FCR tendon on the volar aspect of the wrist. It is crucial to identify the radial artery and protect it during insertion of the cannula. If the outside-in technique is used with an incision made on the ulnar aspect of the FCR tendon, as described by Slutsky, care must be taken to protect the palmar cutaneous and median nerve proper.³⁹

FIGURE 36-12 The palmar portal is the most precarious of all the portals discussed because it lies just adjacent to the radial artery. Open dissection is recommended if this portal is used.

(Photograph courtesy of Pau Galano, MD, Barcelona, Spain.)

CONCLUSIONS

Wrist arthroscopy is a safe and effective technique for treating intra-articular wrist pathology. Complications are rare, and most can be prevented by using proper technique as described in this chapter.