CHAPTER 19 Wrist Arthroscopy: Setup, Anatomy, and Portals

Mark Morishige, Larry D. Field, Felix H. Savoie, III

Wrist arthroscopy has been used since it was first described by Chen in 1979.¹ In the early stages of development, it provided only partial evaluation of the articular surfaces, and it was not used therapeutically. Few investigators routinely used arthroscopic techniques.² It was not until 1986, when Whipple advocated distraction techniques and precise portal placement, that the exposure necessary to perform an extensive evaluation of the wrist joint became an option.³ Even then, diagnosis was the primary function, and therapeutic indications were minimal. Since that time, innovations in wrist arthroscopy have expanded treatment indications and promoted widespread acceptance.

Diagnostic and operative forms of arthroscopy have advanced our understanding of wrist anatomy and function, and arthroscopic techniques have facilitated the repair of previously unrecognized pathology. Continued advances in instrumentation and technology will improve the ability to perform challenging and innovative procedures as the principles of open surgical procedures become adapted to arthroscopy.⁴

Wrist arthroscopy allows close visual examination of the carpal articular surfaces and wrist ligaments, which is often inadequate with open procedures and which can be performed in a less invasive manner than traditional arthrotomy.⁵ The extremely close evaluation of details provides many benefits and increases appreciation of the subtle differences between normal and pathologic anatomy.⁶ This fact alone underscores the importance of a thorough understanding of arthroscopic anatomy.

ANATOMY

The wrist is made up of the eight carpal bones, each with multiple articular surfaces and the intrinsic and extrinsic ligaments, and a triangular fibrocartilage complex (TFCC) that is surrounded by tendons and neurovascular structures (Fig. 19-1).⁷^,⁸ A thorough understanding of the relationship between the surface anatomy of the wrist and these underlying structures is essential to perform accurate arthroscopic portal placement and adequate arthroscopy. Understanding these relationships helps to prevent injury to the cutaneous nerves, tendons, and vascular structures and can minimize the risk to the articular surfaces in the wrist. It also facilitates the use of instruments during procedures, enabling the completion of increasingly complicated arthroscopic wrist procedures.

FIGURE 19-1 Cross-sectional anatomy of the dorsal compartments.

(Modified from Geissler WB, Freeland AE, Weiss AP, Chow JC. Techniques of wrist arthroscopy. Instr Course Lect. 2000:49:225-237.)

To accurately place portals, the surface anatomy should be mapped and labeled before making the first incision. Bony landmarks that should be familiar to the surgeon include Lister’s tubercle, the radius and ulna with their styloids, the radiocarpal joint level, the radial border of the third ray, and the central portion of the fourth ray. The capitate sulcus (i.e., soft spot) also should be palpated.

The extensor retinaculum is an obliquely oriented structure that spans the dorsal distal radius and ulna. It overlies the 12 extensor tendons, which are partitioned into six compartments to prevent bowstringing of the extensor tendons.⁴ The extensor pollicis longus (EPL) is the only tendon in the third compartment, and it is easily palpated, especially after application of traction. This structure passes just ulnar to Lister’s tubercle and should be appropriately marked. The area bordered by the EPL and extensor pollicis brevis together and the extensor carpi radialis longus (ECRL) define the margins of the anatomic snuffbox. The extensor digitorum communis (EDC) is just ulnar to the EPL. The extensor carpi ulnaris (ECU) and the ECRL and ECRB tendons are easily palpated and should be marked. The intersection of these tendons and the bony structures allows accurate identification and precise placement arthroscopy portals (Fig. 19-2).

FIGURE 19-2 Dorsal wrist anatomy and portal locations.

PATIENT EVALUATION

History and Physical Examination

A thorough history and physical examination are essential before proceeding with arthroscopic evaluation of the wrist. It has been said that if no diagnosis can be made after a thorough clinical assessment, little additional information can be obtained from arthoscopy.⁹ A meticulous history helps focus the examiner on the cause and directs the physical examination to the suspected pathology. The examiner must determine the activities that exacerbate or lessen the problem, the functional loss, and the ability of the patient to perform daily activities, including work and leisure activities. The mechanism of injury should be ascertained.

Physical examination is the most accurate method for diagnosing pathology.² A systematic approach to the wrist examination is essential. All joints must be carefully inspected, palpated, and appropriately stressed with the use of provocative tests. Areas of swelling, tenderness, or pain can focus attention on the specific pathology. Examination includes palpation of the tendons and evaluation of the patient’s neurologic and vascular status.