Arthroscopy has revolutionized the practice of orthopaedics by providing the technical capacity to examine and treat intraarticular abnormalities under magnified and brightened conditions. The development of wrist arthroscopy was a natural progression in the successful application of arthroscopy to other larger joints. The wrist itself is a labyrinth of eight carpal bones, multiple articular surfaces, intrinsic and extrinsic ligaments, and a triangular fibrocartilage complex, all within a 5-cm interval. Wrist arthroscopy has continued to undergo considerable development since Whipple and colleagues originally reported the techniques they developed. This complex joint continues to challenge clinicians with an array of potential diagnoses, pathology, and treatment options.
Indications for wrist arthroscopy continue to expand as new techniques and instrumentation are constantly being developed and improved. Diagnostic indications include assessment of the interosseous ligaments, which show a spectrum of injury, as well as evaluation of the array of pathology that may occur on the ulnar side of the wrist, particularly the triangular fibrocartilage complex (TFCC). The use of wrist arthroscopy in managing fractures continues to grow, with management of both distal radius and scaphoid fractures now possible. Wrist arthroscopy is extremely sensitive in detecting chondral defects of both the radiocarpal and midcarpal joints, which are frequently difficult to evaluate with imaging studies alone. These defects may be a source of chronic wrist pain of unknown etiology.
The purpose of this chapter is to present a variety of wrist arthroscopy techniques and describe how they may be applied to an array of pathologic conditions of the wrist.
General Setup for Wrist Arthroscopy
Instrumentation
Use of instruments tailored for small joints is absolutely essential in wrist arthroscopy. Use of instruments developed for arthroscopy of large joints is not appropriate for the small joint of the wrist. In general, a small joint arthroscope that measures 2.7 mm or smaller is used with either a 30- or 70-degree visualization angle. Small joint punches and graspers are used, particularly for management of tears to the articular disk of the TFCC. A small joint shaver that measures 3.5 mm or smaller with varied tips should be available for joint debridement.
Use of traction is essential for visualization. A commercial traction tower may be used, which involves stabilization of the forearm and application of longitudinal force to finger traps that are placed on two or more of the digits. The amount of traction may be adjusted by means of a gear mechanism. Traction towers are now being made with the traction bar at the side of the forearm rather than in the middle, which facilitates the use of fluoroscopy and expands the indication of wrist arthroscopy for management of carpal instability and fractures. An advantage of using the traction tower is that it applies constant traction to the wrist while it is slightly flexed. The slightly flexed position of the wrist makes it easier to insert the wrist arthroscope and other instruments. The improved visualization and increased ability to use instruments in the wrist with newer traction towers continue to expand the indications for treating various wrist pathologies ( Fig. 73-1 ).
If a traction tower is not available, a shoulder holder may be used overhead to support the wrist. A countertraction band is placed around the arm. The wrist may be aligned in a horizontal manner on a hand table, which allows it to be stabilized by a pulley attached to the hand table with weights hanging over the end of the table ( Fig. 73-2 ). Some surgeons prefer the horizontal position for wrist arthroscopy. In general, approximately 10 lb (4.5 kg) of traction is applied.
Portal Placement
Accurate portal placement is vital in wrist arthroscopy because of the small space available in the wrist joint. Appropriate portal placement begins with palpation of anatomic landmarks, first marking the base of the index, long, and ring metacarpals. Next, the radial and ulnar borders of the extensor carpi ulnaris tendon are identified and marked. The radiocarpal joint space may be palpated and marked by rolling the surgeon’s thumb over the dorsal rim of the distal radius and making an impression with the fingernail. The tendons of the extensor pollicis longus and extensor digitorum communis are palpated and marked unless they are obscured by swelling from an acute injury.
After traction is applied, all portals should be drawn on the skin before any incisions are made ( Fig. 73-3 ). The portals are named by their position relative to the dorsal (extensor) tendon compartments. The 3-4 portal is the most common viewing portal and passes between the third and fourth dorsal compartments. This portal is located by palpating the Lister tubercle and moving approximately 1 cm distally until a soft spot is noted between the coursing tendons. Additionally, the 3-4 portal is in line with the radial border of the long finger. The 4-5 portal, which is located between the fourth and fifth dorsal compartments, is the primary working portal. This portal is located by palpating the ulnar aspect of the fourth compartment and identifying the soft spot opposite the 3-4 portal. As a general rule, the 4-5 portal lies slightly more proximal than the 3-4 portal because of the normal radial inclination of the distal radius and is in line with the mid axis of the ring finger. The 6-R and 6-U portals are named according to their position relative to the extensor carpi ulnaris (ECU) tendon, with the 6-R portal being radial and the 6-U portal being ulnar to the tendon. The 6-R portal is generally a working portal, whereas the 6-U portal is frequently used for inflow. Normally, 3 to 5 mL of irrigation fluid is injected into the radiocarpal space through an inflow cannula established at the 6-U portal. As the wrist joint is inflated with irrigation fluid, the dorsal aspect of the 3-4 portal bulges, which further helps localize the proper position of the 3-4 portal. A pressurized pump may include a feedback mechanism to provide uniform pressure flow of irrigation into the joint. When a pump is not available, gravity flow of irrigation fluid is usually sufficient for wrist arthroscopy. Outflow is provided through the arthroscope cannula.
The wrist is suspended in the traction tower with slight flexion. This position facilitates insertion of the arthroscope and other instruments. Before committing to a portal, a needle should be placed in the proposed portal location to ensure that it passes easily into the joint without affecting the distal radius or ulna or the carpus. Portal incisions may be longitudinal or transverse. Transverse portals may be more cosmetic but pose a slightly higher risk of injury to the underlying dorsal radial or dorsal ulnar sensory nerve branches. To avoid injury to these cutaneous nerves, the surgeon uses his or her thumb to pull the skin against the tip of a number 11 scalpel blade along the length of incision ( Fig. 73-4 ). Blunt dissection is carried out with a hemostat to the level of the joint capsule. The arthroscopic cannula with a blunt trocar is placed at an approximate 10-degree angle relative to the long axis of the forearm to enter the radiocarpal joint in line with the normal volar slope of the distal radius ( Fig. 73-5 ).
The radial and ulnar midcarpal portals are made approximately 1 cm distal to the 3-4 and 4-5 portals, respectively. The midcarpal space is somewhat tighter than the radiocarpal space, and care should be taken when entering it with a blunt trocar. A needle is always used first to identify the precise position of the midcarpal portals before incising the skin. The radial midcarpal portal has slightly less room compared with the ulnar midcarpal portal. If the surgeon has difficulty entering the radial midcarpal portal, the arthroscope can be placed in the ulnar midcarpal space first, where more room is available to enter the joint. Inflow is provided through the arthroscopic cannula, and a needle is used to provide outflow in the intercarpal space to improve visualization.
The volar radiocarpal portal is made between the interval of the radioscaphocapitate ligament and the long radiolunate ligament. This portal is most easily established by placing the arthroscope directly at that interval while viewing the volar extrinsic ligaments from the 3-4 portal. A blunt trocar is then inserted into the cannula and gently passed through the volar capsule, tinting the skin on the volar aspect of the wrist. A small incision is made and a second slightly larger cannula may be placed over the arthroscopic cannula or a guide wire passed through the arthroscopic cannula. The trocar then enters the volar aspect of the wrist with this inside-out technique.
Arthroscopic Anatomy
Arthroscopic evaluation of the radiocarpal space begins with the arthroscope in the 3-4 portal and progresses systematically from a radial to ulnar direction. The radial styloid process and distal radius scaphoid facet articulate with the proximal aspect of the scaphoid, and this region is examined for any signs of chondromalacia or synovitis, which may be seen in persons with degenerative arthritis. The volar extrinsic ligaments are then evaluated. The radioscaphocapitate ligament is the most radial extrinsic ligament. The long radiolunate ligament is just ulnar to the radioscaphocapitate ligament and may be two to three times wider ( Fig. 73-6 ). Ulnar to the long radiolunate ligament is the short radiolunate ligament, and the variable radioscapholunate ligament (the ligament of Testut) is actually a neurovascular structure passing at the scapholunate interval.
The normal concave appearance of the scapholunate interosseous ligament is found between the scaphoid and the lunate ( Fig. 73-7 ). The lunate facet of the distal radius and the articular surfaces of the proximal carpal row are inspected for areas of chondromalacia. The articular disk of the TFCC inserts adjacent to the central ulnar rim of the distal radius. The normal thickening of the volar and dorsal radioulnar ligaments is typically well visualized.
A metal probe may be inserted in either the 4-5 or 6-R portal to palpate the TFCC articular disk. This region may be palpated and confirmed to be uniformly taut, similar to the effect on a trampoline. The prestyloid recess is located dorsal to the ulnocarpal ligaments ( Fig. 73-8 ). The prestyloid recess is a normal anatomic finding that is not to be confused with a peripheral tear of the TFCC. The 6-U inflow cannula is traditionally placed through this recess. The extrinsic volar ulnocarpal ligaments and lunotriquetral interosseous ligament are best visualized with the arthroscope in either the 4-5 or 6-R portal. The ulnolunate and ulnotriquetral ligaments are capsular thickenings that are considered part of the TFCC. The lunotriquetral interosseous ligament should have a normal concave appearance between the lunate and triquetrum very similar to that of the scapholunate interosseous ligament.
The midcarpal space is evaluated next. The arthroscope is usually placed in the radial midcarpal space initially, although in smaller wrists, it may be easier to start the examination with the arthroscope in the ulnar midcarpal portal. Once the arthroscope is established in the radial midcarpal portal, the head of the capitate and scapholunate interval are initially identified ( Fig. 73-9 ). The proximal hamate and lunotriquetral interval are viewed as the arthroscope is translated ulnarly ( Fig. 73-10 ). The arthroscope may then be translated radially and distally between the scaphoid and the capitate to visualize the scaphotrapezial trapezoid joint. Accordingly, the trapezoid is found in the foreground and the trapezium is found in the background.
Carpal Instability
Both the radiocarpal and midcarpal space should be evaluated arthroscopically when carpal instability is suspected. The key to arthroscopic management of carpal instability is the recognition of what is normal and what is pathologic when viewing the integrity of the interosseous ligaments and the overall alignment of the carpal bones. The interosseous ligaments may stretch and deform significantly before they eventually tear. Consequently, bulging of the interosseous ligament and rotation of the carpal bones are possible prior to true intercarpal dissociation. Extrinsic ligaments also contribute to wrist stability. A combination of both intrinsic and extrinsic pathology may lead to carpal malalignment and clinical instability. The scapholunate and lunotriquetral interosseous ligaments should have a normal concave appearance as seen from the radiocarpal space. The scapholunate interosseous ligament is best seen with the arthroscope in the 3-4 portal, and the lunotriquetral interosseous ligament is best seen with the arthroscope in either the 4-5 or 6-R portal. As viewed from the midcarpal space, the scapholunate interval should be highly congruent without any notable step-off between carpal bones. The lunotriquetral interval should also be congruent, but a 1-mm distal step-off between carpal bones is normally seen. A small amount of motion is possible at the lunotriquetral interval and should not be mistaken for instability.
A limited type of intraoperative arthrogram (poor man’s arthrogram) may be performed for evaluation of carpal instability. To perform this procedure, a needle is placed in either the radial or ulnar midcarpal portal, and a tear of the interosseous ligament is strongly suspected when a free flow of irrigation fluid occurs from the radiocarpal space and exits the needle.
A spectrum of interosseous ligament injury is possible. The ligament progresses from attenuation to frank tearing in a volar to dorsal direction. Geissler et al. devised an arthroscopic classification of carpal instability based on observations of injury to the scapholunate and lunotriquetral interosseous ligaments when associated with fractures of the distal radius ( Table 73-1 ).
| Grade | Description | Management |
|---|---|---|
| I | Attenuation or hemorrhage of the interosseous ligament as seen from the radiocarpal space No incongruence of carpal alignment as seen from the midcarpal space | Cast immobilization |
| II | Attenuation or hemorrhage of interosseous ligament as seen from radiocarpal space Incongruence or step-off less than the width of a probe as seen from the midcarpal space | Arthroscopic pinning |
| III | Incongruence or step-off greater than the width of a probe as seen from both the radiocarpal and midcarpal spaces | Arthroscopic pinning/open repair |
| IV | Incongruence and gross instability allowing passage of a 2.7-mm arthroscope as seen from both the radiocarpal and midcarpal spaces | Open repair |
In grade I injuries, the normal concave appearance between the carpal bones is lost. The interosseous ligament bulges with a convex appearance, as seen with the arthroscope in the radiocarpal space. Evaluation of the midcarpal space shows the carpal bones to be highly congruent without step-off. In grade II injuries, the interosseous ligament is again convex as seen with the arthroscope in the radiocarpal space. From the midcarpal space, the carpal bones are no longer congruent ( Fig. 73-11 ). With early scapholunate instability, the scaphoid is observed to flex as the dorsal edge is distal to the lunate; however, the gap is minimal. Slight motion at the lunotriquetral articulation is not pathologic in most instances and should be correlated with ligament integrity and degree of interval dissociation. In grade III injuries, the interosseous ligament begins to tear and a larger gap is seen between the carpal bones from both the radiocarpal and midcarpal spaces ( Fig. 73-12 ). In grade IV injuries, the interosseous ligament is completely detached, and the arthroscope may be passed freely from the radiocarpal to the midcarpal space through the affected interval, which is designated as the “drive-through sign.” This sign often corresponds with an excessively widened scapholunate (or lunotriquetral) gap on a posteroanterior radiograph of the wrist, indicative of intercarpal dissociation.
Grade I injuries are considered mild wrist sprains that typically resolve with conservative management. If detected intraoperatively at the time of concurrent evaluation and treatment of other wrist injuries, arthroscopic débridement of the partially injured interosseous ligament may be performed. Acute grade II (and some grade III) tears of the scapholunate or lunotriquetral interosseous ligaments that result in incongruence from the midcarpal space, however, may be arthroscopically reduced and temporarily pinned to provide stabilization. Two or three Kirschner wires (K wires) are placed just distal to the radial styloid into the scaphoid under fluoroscopic guidance. It is important to place the guide wires either through a protective cannula or in oscillation mode to avoid injury to traversing cutaneous nerve branches. The wrist is then suspended in the traction tower, and the arthroscope is placed in the ulnar midcarpal portal. A joystick K wire may be placed into the lunate to help control rotation. The scapholunate interval is anatomically reduced, as viewed from the midcarpal space, and the K wires are advanced across the scapholunate interval. Frequently, droplets of fat are seen exiting the scapholunate interval. These wires are left in position for approximately 8 weeks. The wrist is immobilized in a below-elbow cast. The decision about whether to leave the K wires protruding from the skin is made by the surgeon. Digital range of motion is encouraged. The wires are removed at 8 weeks and the wrist is immobilized for an additional 4 weeks. Outpatient therapy for range of motion and strengthening is initiated after a 3-month interval.
Management of grade II or III acute tears of the lunotriquetral interosseous ligament is essentially the same except that the arthroscope is placed in the radial midcarpal space as the pins are driven across the lunotriquetral interval from ulnar to radial. Again, protective measures are undertaken to prevent iatrogenic cutaneous nerve injury. Anecdotally, reduction of the lunotriquetral interval is usually less difficult compared with reduction of the scapholunate interval.
In persons with grade IV interosseous ligament dissociation, arthroscopic management alone is inadequate to restore alignment and stability, and an open approach is recommended. Multiple methods of interosseous ligament repair and/or reconstruction have been previously described and are beyond the scope of this chapter.
Whipple reviewed the results of arthroscopic treatment of scapholunate instability in patients who were followed up for a duration of 1 to 3 years. Patients were classified in two distinct groups of 40 patients each according to the duration of symptoms and the side-to-side scapholunate gap. Eighty-three percent of patients who had scapholunate instability of 3 months or less and a gap of 3 mm or less experienced relief of their symptoms, compared with only 21 patients (63%) who had symptoms longer than 3 months and more than a 3-mm side-to-side difference. The conclusion from the study was that arthroscopic pinning should be reserved for patients with an acute injury rather than a chronic, complete tear.
Osterman and Seidman reviewed their results of arthroscopic treatment of acute lunotriquetral instability in 20 patients who did not have volar intercalated segment instability. Follow-up was an average of 32 months, and 16 patients had good to excellent relief of pain. Grip strength improved in 18 patients.
Weiss and colleagues reviewed their results of arthroscopic debridement alone of interosseous ligament tears with an average of 27 months of follow-up after the procedure. In this study, 31 of 36 patients who had a partial tear of the scapholunate interosseous ligament had complete resolution or a decrease in their symptoms compared with 19 of 21 patients who had a complete tear of the scapholunate interosseous ligament. All 42 patients who had a partial tear of the lunotriquetral interosseous ligament and 26 of 33 patients who had a complete tear of the lunotriquetral interosseous ligament experienced complete resolution or a decrease in their symptoms. Grip strength improved an average of 23% in this study. The investigators concluded that debridement of lunotriquetral interosseous ligament tears had a better result compared with injury to the scapholunate interosseous ligament. In addition, debridement of partial tears provided better results compared with complete tears.
Although electrothermal shrinkage of ligaments has failed to show consistent effectiveness elsewhere, this technique may play a role in the management of chronic partial tears of the interosseous wrist ligaments. Electrothermal shrinkage is based on heating and denaturing of collagen, resulting in fiber contraction, and likely is best for a grade I or II partial interosseous ligament injury. After debridement of the torn ligament edges, an electrothermal probe is used to shrink the uninjured portion of the ligament. A monopolar or bipolar probe may be used. The monopolar probe has been shown to have deeper penetration of heat than the bipolar probe. On the other hand, bipolar probes yield higher surface temperatures, which may have the undesirable effect of increasing the temperature of the irrigation fluid medium. It is important not to paint the entire tissue but rather to spot weld and leave viable tissue in between the contracted areas ( Fig. 73-13 ). The probe is primarily directed at the membranous portion of the interosseous ligament, but the dorsal and volar wrist capsule may be included in the procedure.
