Wrist Arthroscopy: Setup, Anatomy, and Portals

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CHAPTER 19 Wrist Arthroscopy: Setup, Anatomy, and Portals

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.

image

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).

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.

TREATMENT

Indications and Contraindications

Wrist arthroscopy provides an accurate complement to the probable diagnosis obtained from the physical examination. Arthroscopy is useful for evaluation of patients with wrist pain and motion loss when noninvasive studies have failed to provide a diagnosis, and it is more sensitive than arthrography for evaluating pathology.8 Diagnosis of interosseous ligaments tears and the degree of carpal instability can be accurately determined using arthroscopy. It is also useful in patients with well-defined pathology, such as nonunions, Kienbock’s disease, and scapholunate or lunotriquetral dissociations, for which evaluation of the articular surfaces is of prognostic and therapeutic importance.

Although once used almost exclusively for diagnostic purposes, the therapeutic indications for wrist arthroscopy continue to expand. Arthroscopic treatment is indicated for loose body removal, synovectomy, intra-articular adhesion release, lavage of a septic wrist, débridement of chondral lesions, hypertrophic or torn ligaments, and tears of the TFCC. It has also been used for dorsal ganglion excision and provides a useful adjunct in the reduction of distal radius and scaphoid fractures. Bone excision procedures, such as radial styloidectomy and partial resection of the distal ulna (i.e., wafer procedures), have been performed arthroscopically. Arthroscopy has been described for advanced procedures, such as proximal row carpectomy, excision of the proximal pole of the scaphoid, lunate excision in Kienbock’s disease, and capitolunate arthrodesis.7,8

Contraindications to wrist arthroscopy are limited mainly to conditions of trauma or swelling that distorts the normal anatomy or significantly damages capsular integrity, leading to fluid extravasation.

Arthroscopic Technique

Setup

A significant improvement in wrist arthroscopy came with the innovation of wrist distraction. This key element enhanced the surgeon’s ability to perform arthroscopic procedures in the confined wrist joint. Distraction is essential to improve visualization and provide adequate space for maneuverability during wrist arthroscopy, because distention of the joint alone does not provide adequate room for instrumentation.2 Several options exist to provide the necessary distraction. A dedicated sterile or nonsterile traction tower is a popular choice. Alternatives include the use of horizontal traction with a pulley and weight system and a nonsterile traction boom device (Figs. 19-3 to 19-5).

We prefer a sterile traction tower with nylon finger traps. It provides convenient application of wrist distraction in flexion, extension, and radial and ulnar deviation. This system allows adjustability to the distraction force and the position of the wrist, and it permits easy conversion to open procedures if necessary. The traction tower system maintains the wrist in a stable position for portal preservation during the exchange of instruments.2

The arm is placed in an abducted position, and the upper arm is secured to the traction tower. A nonsterile tourniquet is applied, and the arm and hand are prepared and draped with the forearm in a vertical position (Fig. 19-6). We use sterile soft nylon finger traps to secure the index and long finger to the tower for most procedures. Soft traps increase the surface area and distribute the force better than wire devices. For patients with poor or fragile skin, additional fingers in the traps can decrease the force to the skin.2 To improve visualization for ulnar-sided pathology, we frequently use the index and ring fingers (Fig. 19-7). Most procedures require 5 to 10 pounds of traction.

Equipment

Proper equipment is essential to perform a quality wrist arthroscopy. A video arthroscope and monitor with printer and video recorder are used to document the intra-articular findings. In addition to adequate visualization, a major improvement came with the innovation of instruments specifically designed for use in small joints. Larger instrumentation used for knee and shoulder arthroscopy is not adequate for procedures in the wrist. A 2.0- to 3.0-mm-diameter arthroscope is essential to allow adequate mobilization without the risk of injury to surrounding structures and articular surfaces. In addition to the standard 30-degree arthroscope, a 70-degree arthroscope is occasionally useful.

Other small joint arthroscopy equipment is available and necessary for mastery of wrist arthroscopy. Equipment includes a small joint shaver (2.7 or 2.9 mm) with multiple tips, a wrist probe (1.7 or 2.0 mm), and many of the smaller versions of large joint arthroscopic instruments.5,7 As arthroscopy has advanced, more specialized equipment has become available, including TFCC repair kits, retrograde retrievers, ablation shrinkage devices, and fracture fixation devices. Spinal needles and passing sutures are helpful tools that have been adapted from other arthroscopic repair techniques.

Clear physiologic crystalloid solution, such as lactated Ringer’s solution, is preferable because it can be rapidly absorbed into the tissues and can prevent overdistention. Irrigant can be introduced through the sheath of the arthroscope or by separate inflow and outflow portals. Gravity inflow has proved adequate in our practice. Pinch chambers can introduce small boluses of irrigant to clear the visual field.2 Fluid pumps that can precisely control the pressure in the joint are available. However, pressurized injection increases the risk of fluid extravasation into subcutaneous tissue and is usually unnecessary.

Portals

Wrist arthroscopy portals include radiocarpal, midcarpal, distal radioulnar, and volar portals. Traditionally, arthroscopic viewing portals are described by their relation to the six extensor compartments of the wrist. Eleven historical access portals typically are used. They include five radiocarpal, four midcarpal, and two distal radioulnar portals. Two additional volar portals have become increasingly popular.

Precise portal placement is essential for performing a complete wrist arthroscopy and for minimizing iatrogenic injury to the wrist joint and surrounding structures. Placing the portals in an incorrect manner can result in damage to neurovascular structures and the articular cartilage. All portals and surface landmarks should be marked on the skin. Marking portals after the application of traction helps to prevent distortion and improperly placed portal sites (Fig. 19-8).

Radiocarpal Portals.

Radiocarpal portals include the 3-4, 4-5, 6-R, 6-U, and 1-2 portals. Radiocarpal portals show smooth carpal articulations, whereas the midcarpal portals show more irregular articulations.5 Portals are named according to the interspace between extensor compartments. The 3-4 portal divides the third and fourth extensor compartments. The 6-R and 6-U portals are named by their relationship to the ECU, with the 6-R on the radial aspect and the 6-U on the ulnar aspect.7 Palpation between these compartments demonstrates soft spots of the wrist, which provide the least traumatic entry points into the joint.

The 4-5 Portal.

The 4-5 portal is bordered on the radial side by EDC, on the ulnar side by the extensor digiti quinti (EDQ), proximally by the attachment of the radius and the TFCC, and distally by the lunate. It is established 1 cm ulnar and slightly more proximal to the 3-4 portal because of the inclination of the radius.7 It can be found by palpating the soft spot directly ulnar to the EDC. A spinal needle should then be placed just proximal to the lunate. Entry through this portal places instruments directly adjacent to the midportion of the TFCC.12 The 4-5 portal is typically the main working portal for instrumentation on the ulnar side of the wrist. It may also be used as a viewing portal for ulnar sided structures. This portal has minimal neurovascular risk unless there is an aberrant branch of the SBRN.11

Midcarpal Portals.

Midcarpal evaluation should be done as a routine part of wrist arthroscopy. The four midcarpal portals include the midcarpal radial, midcarpal ulnar, triquetrohamate, and triscaphe portals. The most commonly used are the radial and ulnar midcarpal portals. The less common ones are the triscaphe and the triquetrohamate portals. The very limited room in the midcarpal space requires extra care when entering the joint. Once established, these portals should be maintained to minimize the difficulty in re-establishing them due to fluid extravisation.7 Normally, there is no communication between the radiocarpal and midcarpal spaces.

Evaluation of wrist instability with midcarpal arthroscopy is better than with radiocarpal arthroscopy alone. Studies show that instability of the scapholunate or lunotriquetral ligament diagnosed with radiocarpal arthroscopy was always seen on midcarpal arthroscopy, but instability seen by midcarpal arthroscopy was not always noticed when performing radiocarpal arthroscopy alone. Grading of the instability was equal to or greater than that done by midcarpal examination.13

Visualization of the scaphoid-trapezoid-trapezium (STT) joint, the midcarpal extrinsic ligaments, the capitohamate joint, and the articular surfaces of the midcarpal bones is improved with midcarpal arthroscopy. Midcarpal arthroscopy can be mastered quickly and adds little time to wrist arthroscopy. It has a low morbidity rate and should be used routinely for a thorough evaluation of the wrist.13

Triscaphe Portal.

The triscaphe portal (STT) is on the radial side of the midcarpal space. It is established ulnar to the EPL or radial to the abductor pollicis longus in line with the radial margin of the second metacarpal at the level of the distal pole of the scaphoid. The STT-R portal provides an additional view and access to the STT joint.14 Staying ulnar to EPL helps to avoid the radial artery. The ulnar aspect of the ECRL tendon can be used to check the location of this portal, because the EPL is quite mobile at the level of the STT joint. Care must be taken to prevent displacing the tendon radially while establishing the STT portal to protect the radial artery. The STT joint can be entered directly through this portal, and it is used primarily for instrumentation in this joint.12 Care should be taken to avoid the small terminal branches of the SBRN.

Volar Portals.

Volar portals have become increasingly popular to complete the view of diagnostic wrist arthroscopy and to provide access for procedures that are not feasible from the dorsal entry sites. Bain and colleagues suggested a box approach to wrist arthroscopy (Fig. 19-10).4 By using portals around the circumference of the wrist, visualization and access to all surfaces within the wrist are improved.15 The viewing and working portals can then be adjusted for the specific diagnostic or therapeutic procedure.4 The volar portals allow improved treatment for dorsal pathology, such as dorsal rim fractures of the distal radius, dorsal rheumatoid synovial proliferation, and volar segment tears of the scapholunate and lunotriquetral interosseous ligaments.15

image

FIGURE 19-10 Box concept using dorsal and volar portals as the viewing and working portals to encircle the wrist.

(Modified from Bain GI, Munt J, Turner PC. New advances in wrist arthroscopy. Arthroscopy. 2008:24:355-367.)

Volar Radial Portal.

To place the volar radial (VR) portal, a mini-open technique is used over the flexor carpi radialis on the radial side of the volar proximal wrist crease. An anatomic study found that there was a safe zone that included the width of the flexor carpi radialis and at least 3 mm in all directions at this level from the palmar cutaneous branch of median nerve (ulnarly) and the radial artery (radially).16 Because of this safe zone, a 2-cm transverse incision can be made over the flexor carpi radialis tendon. The transverse incision provides superior cosmesis while maintaining minimal risk for the volar structures. The tendon sheath is divided, the radial artery is retracted radially, and the flexor carpi radialis and median nerve are retracted ulnarly. The radiocarpal joint is identified with a spinal needle, and the portal is opened with a blunt instrument. This portal is used to assess the dorsal aspect of the scapholunate interosseous ligament and the dorsal radiocarpal ligament.16

Neurovascular Structure Risk

Because of the absence of major neurovascular structures, most wrist arthroscopy uses the dorsum of the wrist. Only the deep branch of the radial artery and the superficial dorsal sensory branches of the radial, ulnar, and lateral antebrachial cutaneous nerves are located on the dorsal side of the wrist.8 Injury to these structures can cause numbness and, at worst, a painful neuroma and complex regional pain syndrome. Certain portals have an increased risk of iatrogenic neurovascular injury. The greatest risk to the radial artery and dorsal radial and ulnar sensory nerve branches occur with the 1-2, 6R, and 6-U portals. The midcarpal, 3-4, 4-5, and distal radioulnar joint portals are relatively safe.

Risk does exists even in safe portals because aberrant sensory nerve branches can be dangerously close.11 This usually necessitates incisions that are longitudinal and are made by pulling only the skin over a blade and bluntly spreading through the subcutaneous tissue. When piercing the capsule, only a blunt trocar should be used. This technique helps protect structures between the dermis and capsule from injury.11

COMPLICATIONS

Complications during and after wrist arthroscopy are rare. Most physicians report rates of less than 2%.4,5 A study of 210 patients reported only two (0.9%) major complications and nine (4.3%) minor complications, all of which resolved with observation. The most common complication was dorsal ulnar sensory neuropraxia, and it was associated with open procedures.19 Complications can be the result of traction and arm positioning or related to establishment of portals. They can be procedure-specific complications or general arthroscopic complications. Major complications include compartment syndrome, permanent nerve injury, postsurgical joint infection, vascular injury, complex regional pain syndrome, permanent stiffness, and tendon rupture.19

Most complications can be prevented if the risks are understood and simple precautions are used when performing the surgery. Large instrumentation within a small joint space predisposes to iatrogenic injuries to nerves, the radial artery, and extensor tendons. The EPL and EDQ are the tendons most at risk during wrist arthroscopy. Flexible nylon finger traps help prevent skin damage for patients with friable skin.4 Using a spinal needle ensures an adequate pathway, and blunt trocars help to minimize risk to the articular surfaces.

Excessive extravasation of fluid may occur in recently injured patients with torn capsules or if the inflow cannula is placed extra-articularly. If extravasation occurs, the causative factor should be addressed, or the arthroscopic portion of the procedure should be stopped. Pressure diminishes quickly when the inflow is halted, and elevating the extremity is usually all that is necessary for correction. Physiologic solutions allow better fluid absorption in the soft tissues and further decrease the risk of extravasation.7 Whipple reports the risk of compartment syndromes is minimal to none because, even in the case of intra-articular fractures, extravasated fluid is rapidly absorbed by clysis and does not increase compartment pressures long enough to compromise circulation. Caution is advised if pressure pumps are used.20

Postoperative infection is uncommon. If there is any evidence of superficial infection, oral antibiotics are usually sufficient. If a deep intra-articular infection develops, irrigation, arthroscopic débridement, and intravenous antibiotic therapy are usually required.21

REFERENCES

1. Chen YC. Arthroscopy of the wrist and finger joints. Orthop Clin North Am. 1979;10:723-733.

2. Whipple TL, Cooney WP3rd, Osterman AL, Viegas SF. Wrist arthroscopy. Instr Course Lect. 1995;44:139-145.

3. Whipple TL, Marotta JJ, Powell JH3rd. Techniques of wrist arthroscopy. Arthroscopy. 1986;2:244-252.

4. Bain GI, Munt J, Turner PC. New advances in wrist arthroscopy. Arthroscopy. 2008;24:355-367.

5. Haisman JM, Matthew B, Scott W. Wrist arthroscopy: standard portals and arthroscopic anatomy. J Am Soc Surg Hand. 2005;5:175-181.

6. Berger RA. Arthroscopic anatomy of the wrist and distal radioulnar joint. Hand Clin. 1999;15:393-413. vii

7. Geissler WB, Freeland AE, Weiss AP, Chow JC. Techniques of wrist arthroscopy. Instr Course Lect. 2000;49:225-237.

8. Gupta R, Bozentka DJ, Osterman AL. Wrist arthroscopy: principles and clinical applications. J Am Acad Orthop Surg. 2001;9:200-209.

9. Jones WA, Lovell ME. The role of arthroscopy in the investigation of wrist disorders. J Hand Surg Br. 1996;21:442-445.

10. Maizlin ZV, Brown JA, Clement JJ, et al. MR arthrography of the wrist: controversies and concepts. Hand (N Y). 2009;4:66-73.

11. Abrams RA, Petersen M, Botte MJ. Arthroscopic portals of the wrist: an anatomic study. J Hand Surg Am. 1994;19:940-944.

12. Bettinger PC, Cooney WP3rd, Berger RA. Arthroscopic anatomy of the wrist. Orthop Clin North Am. 1995;26:707-719.

13. Hofmeister EP, Dao KD, Glowacki KA, Shin AY. The role of midcarpal arthroscopy in the diagnosis of disorders of the wrist. J Hand Surg Am. 2001;26:407-414.

14. Carro LP, Golano P, Farinas O, et al. The radial portal for scaphotrapeziotrapezoid arthroscopy. Arthroscopy. 2003;19:547-553.

15. Abe Y, Doi K, Hattori Y, et al. A benefit of the volar approach for wrist arthroscopy. Arthroscopy. 2003;19:440-445.

16. Slutsky DJ. Wrist arthroscopy through a volar radial portal. Arthroscopy. 2002;18:624-630.

17. Slutsky DJ, Nagle DJ. Wrist arthroscopy: current concepts. J Hand Surg Am. 2008;33:1228-1244.

18. del Pinal F, Garcia-Bernal FJ, Pisani D, et al. Dry arthroscopy of the wrist: surgical technique. J Hand Surg Am. 2007;32:119-123.

19. Beredjiklian PK, Bozentka DJ, Leung YL, Monaghan BA. Complications of wrist arthroscopy. J Hand Surg Am. 2004;29:406-411.

20. Whipple TL. Precautions for arthroscopy of the wrist. Arthroscopy. 1990;6:3-4.

21. Botte MJ, Cooney WP, Linscheid RL. Arthroscopy of the wrist: anatomy and technique. J Hand Surg Am. 1989;14:313-316.