Wrist Arthroscopy

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.

Wrist arthroscopy has been used since it was first described by Chen in 1979.

Wrist Arthroscopy Indications

Wrist Arthroscopy Indications may be a diagnostic or therapeutic.

Diagnostic Indications include:

1. Wrist arthroscopy provides an accurate complement to the probable diagnosis obtained from the physical examination.
2. Wrist 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.
3. Diagnosis of interosseous ligaments tears and the degree of carpal instability can be accurately determined using arthroscopy.
4. It is also useful in patients with well-defined pathology, such as nonunions, Kienbock’s disease, and scapholunate or lunotriquetral dissociations.

Therapeutic indications include:

1. Arthroscopic wrist surgery 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.
2. It has also been used for dorsal ganglion excision and provides a useful adjunct in the reduction of distal radius and scaphoid fractures.
3. Bone excision procedures, such as radial styloidectomy and partial resection of the distal ulna (i.e., wafer procedures), have been performed arthroscopically.
4. Wrist 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.

See Also: Wrist Anatomy

Wrist Arthroscopy Portals

Wrist arthroscopy portals include:

1. Radiocarpal,
2. Midcarpal,
3. Distal radioulnar,
4. Volar portals.

Traditionally, wrist arthroscopy 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.

Radiocarpal Portals:

Radiocarpal portals for wrist arthroscopy 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. 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. Palpation between these compartments demonstrates soft spots of the wrist, which provide the least traumatic entry points into the joint.

The 3-4 Portal:

The 3-4 portal is usually the first portal established, and it is the primary viewing portal. It is bordered on the radial side by the EPL and ECRB, on the ulnar side by the EDC, on the proximal side by the distal radius, and on the distal side by the scapholunate ligament. The 3-4 portal is established 1 cm distal to Lister’s tubercle, and it is located by palpating the distal edge of the radius between the ulnar border of the ECRB and the radial margin of the EDC in line with the radial border of the long finger.

This is the soft spot between the third and fourth compartments. A spinal needle is then inserted parallel to the radial articular surface at about 10 degrees, matching the palmar tilt. This portal is the workhorse of standard wrist arthroscopy and provides a broad view of most of the radiocarpal joint on the volar side. The portal is relatively safe, with the sensory branch of the radial nerve (SBRN) a mean distance of 16 mm and a mean distance from the radial artery of 26.3 mm.

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. 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. 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.

The 6-R Portal:

Frequently used as an alternative to the 4-5 portal, the 6-R portal is bordered radially by the EDQ, ulnarly by the ECU, proximally by the TFCC, and distally by the lunotriquetral joint. It enters the wrist joint just distal to the ulnar attachment of the TFCC. This portal is found by using the proximal border of the triquetrum rather than distal ulna as a surface landmark to avoid damaging the TFCC.

It is establish under arthroscopic guidance by introducing a needle just radial to the ECU. The 6-R portal is typically used for instrumentation or for outflow. It also provides visualization of the TFCC and the ulnolunate, ulnotriquetral, and interosseous lunotriquetral ligaments. The 6-R has a mean distance of 8.2 mm from the dorsal sensory branch of the ulnar nerve (DBUN).

The 6-U Portal:

The 6-U portal is established volar to the ECU tendon, but because of its proximity to the DBUN, it is not routinely used. The skin incision may be placed as far volar as the dorsal border of the ECU tendon. The portal enters the wrist joint through the prestyloid recess between the ECU tendon and the ulnar styloid. The portal is distal to the TFCC and dorsal ulnar to the ulnotriquetral ligament.

The 6-U portal is typically used for the inflow or outflow cannula. It may be used as an accessory portal for viewing ulnar-sided structures or for instrumentation during TFCC repairs. The mean distance of the portal to the DBUN is 4.5 mm, but the nerve can have multiple branches in some patients.

The 1-2 Portal:

The 1-2 portal is not used frequently. It is established between the first and second extensor compartments 1 to 2 mm distal to the radial styloid. This portal is placed by finding the soft spot between the first extensor compartment containing the abductor pollicis longus and extensor pollicis brevis and the second compartment with the ECRL and ECRB tendons along the far ulnar part of the anatomic snuffbox. It is located just proximal to the waist of the scaphoid. The radial artery is located at the volar and radial aspect of the anatomic snuffbox.

This necessitates placement of this portal as far dorsal as possible to avoid injury to the artery. The 1-2 portal provides access to the radial styloid, scaphoid, and articular surface of the distal radius, but it allows only a limited view of the lunate. There is significant risk with the placement of this portal. Two branches of the SBRN are a mean distance of 3 mm radial and 5 mm ulnar to the portal, and the radial artery is a mean distance of 3 mm radial to the portal.

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.

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. Grading of the instability was equal to or greater than that done by midcarpal examination. 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.

Midcarpal Radial Portal:

The radial midcarpal portal is the most commonly used midcarpal portal. It is bordered radially by the ECRB, ulnarly by the EDC, proximally by the scapholunate ligament, and distally by the capitate. It should be established in line with the radial border of the third metacarpal, 1 cm distal to the 3-4 portal.

A soft spot may be palpated on the radial side of the proximal capitate between the base of the third metacarpal and the dorsal margin of the distal radius. The arthroscope enters between the capitate and scaphoid. This allows evaluation of the midcarpal space and the scapholunate, lunotriquetral, and STT articulations. This portal is relatively safe, with branches of the SBRN found radially at a mean distance of 15.8 mm.

Midcarpal Ulnar Portal:

The midcarpal ulnar portal is bordered radially by the EDC, ulnarly by the EDQ, proximally by the lunotriquetral joint, and distally by the capitate hamate joint. It is in line with the center of the fourth metacarpal. As with the radial midcarpal portal, it is placed approximately 1 cm distal to the 4-5 portal and at about the same level as the radial midcarpal portal.

This portal enters through capitate-hamate-triquetral-lunate interval. It is used primarily for instrumentation within the midcarpal joint. There is minimal risk when making this portal because the SBRN branches are usually remote to this portal.

Triquetrohumate Portal:

The triquetrohumate portal is established on the ulnar side of the wrist, distal to the triquetrum and ulnar to the midcarpal ulnar portal. The EDQ borders it on the radial side and the end of the ECU on its ulnar side. It enters the triquetrohumate joint just ulnar to the ECU tendon. It provides excellent access for an inflow or outflow canula and can be used for instrumentation in the triquetrohumate joint.

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. 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. 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. By using portals around the circumference of the wrist, visualization and access to all surfaces within the wrist are improved.

The viewing and working portals can then be adjusted for the specific diagnostic or therapeutic procedure. 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.

Volar Radial Portal:

To place the volar radial (VR) portal, a miniopen 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). 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.

Volar Ulnar Portal:

Placement of the volar ulnar portal uses a mini-open technique. A 2-cm longitudinal incision is centered over the proximal wrist crease along the ulnar edge of the common flexors. The interval between the flexor carpi ulnaris and common flexor tendons is then used. The common flexors are retracted radially, and the flexor carpi ulnaris and the ulnar nerve are retracted ulnarly.

The joint space is identified with a spinal needle, and the capsule is again opened bluntly. Because there is no true safe zone for the volar ulnar portal, it requires a careful dissection and spread technique. This portal provides access for reduction of a distal radius fracture and a view of the dorsal articular surfaces and dorsal ligaments.

Distal Radioulnar Portals

The distal radioulnar joint (DRUJ) is difficult to examine, and wrist arthroscopy is not frequently used in these cases. The proximal and distal DRUJ portals are named according to their location proximal or distal to the ulnar head. The DRUJ portals are bordered radially by the EDC and ulnarly by the ECU. The joint is entered from at the base of the DRUJ, bordered by the radius and ulna.

The proximal portal is placed in this line just proximal to the DRUJ. The forearm is supinated to relax the dorsal capsule, and the arthroscope is then introduced between the radius and ulna underneath the TFCC and proximal to the articular surface. The radioulnar articular surfaces can then be seen. Pronation and supination increase the available surface area during examination.

The distal portal is not always accessible. Use of this portal allows the surgeon to examine the distal articular surface of the ulna and the undersurface of the TFCC. The DRUJ portal uses a mini-open approach. It is located just proximal to the TFCC, and care must be taken to stay below the TFCC to prevent injury to this structure. There is some risk to the posterior interosseous nerve. There is minimal risk to sensory nerves, with the closest 17.5 mm distally.

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. 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. 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.

Dry Wrist Arthroscopy

A newer technique that uses arthroscopic wrist surgery without irrigation has been tried. Proponents claim that there are benefits to arthroscopy without water, including limiting loss of vision and compartment syndrome. Another possible advantage is the ability to do open procedures without soft tissue infiltration. The investigators also suggest the possibility of less pain and swelling after surgery. No prospective studies have evaluated these reported benefits, and this technique is still in its early stages.

References

1. Chen YC. Arthroscopy of the wrist and finger joints. Orthop Clin North Am. 1979 Jul;10(3):723-33. PMID: 460845.
2. Whipple TL, Cooney WP 3rd, Osterman AL, Viegas SF. Wrist arthroscopy. Instr Course Lect. 1995 ; 44 : 139 – 145 .
3. Whipple TL, Marotta JJ, Powell JH 3rd . 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 .