Preprocedural Planning
The space available for wrist arthroscopy and instrumentation is substantially smaller than that available in the larger joints. Knowledge of the normal wrist anatomy, accurate portal placement, and smaller instrumentation are the most important aspects of successful wrist arthroscopy and are critical for the examination, probing, and treatment of all areas. [34, 35]
Traction
Traction is essential and is usually accomplished with a traction tower (CONMED Linvatec, Largo, FL), as shown in the image below. This device allows easy access to all areas of the wrist, and the degree of traction can be adjusted.
Alternatively, a shoulder-holder can be used overhead to support the wrist. [36] The wrist can also be aligned horizontally on a hand table; the arm is stabilized by a pulley or a padded post that is attached to the hand table. Traction is provided via finger traps that are attached to a 10-lb (4.5-kg) weight that is suspended over the end of the hand table.
Large-joint instrumentation such as that used for shoulder and knee arthroscopy is not appropriate; instrumentation that is specifically designed for small joints is essential for successful performance and visualization of arthroscopy in the wrist. [37]
Portals
Inappropriate portal placement can injure the articular cartilage or the triangular fibrocartilage complex (TFCC); therefore, the appropriate small-bore arthroscope must be available. It is usually 2.7 or 2.9 mm in diameter and generally has a 30° or 70° visualizing angle.
A video printer is helpful for documenting critical aspects of the arthroscopic procedure, and a small probe that is designed for wrist arthroscopy aids the examination of tissues through manipulation. In addition, a small-joint shaver with various tips is essential for the debridement of torn or avulsed tissue, and various angled punches or grabbers are useful for debridement or removal of tissue.
After traction is applied, all portals should be drawn on the skin (see the image below). The bases of the index-, long-, and ring-finger metacarpals are marked, as well as the extensor carpi ulnaris, which becomes prominent after traction. The dorsal lip of the radius should be identified. Provided that the wrist is not swollen from an acute injury, the extensor pollicis longus and extensor digitorum communis tendons can be palpated and marked.
The wrist is suspended in the traction tower, and the portals are drawn with the associated landmarks on the extensor surface of the wrist.
Portals are named according to the interspace through which they course with respect to the extensor compartments, as follows:
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The 3-4 portal travels between the third and fourth dorsal compartments and is located by palpating the Lister tubercle and moving the finger approximately 1 cm distally until a soft spot is noted; this portal is also in line with the radial border of the long finger
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Generally, the 4-5 portal lies slightly more proximal than the 3-4 portal and is located by noting the soft spot opposite the 3-4 portal on the ulnar side of the fourth compartment; the surgeon must remember the normal angle of inclination at the distal aspect of the radius (radial inclination)
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The 6-R and 6-U portals are named on the basis of their positions relative to the extensor carpi ulnaris tendon, with 6-R being the radial side of the sixth compartment and 6-U being the ulnar side
The wrist joint should be inflated with irrigation before the trocar is introduced. This can be accomplished by placing a separate inflow portal or by introducing 3-5 mL of irrigation into the radiocarpal space. As fluid enters the joint, the dorsal capsule in the 3-4 portal bulges. Pressurized, controlled pumps can assist in maintaining a constant pressure or flow to prevent fluid extravasation. Alternatively, gravity-fed inflow irrigation through an arthroscopic sheath or via a separately placed 16- or 18-gauge cannula can be used. Inflow can be controlled with a pinch pump of the infusion line or by having an assistant regulate it with a 50-mL syringe. [38]
Portal incisions should be longitudinal to the extensor tendons so that the tendons are not accidentally transected if the blade is passed too deeply. To facilitate ideal incision placement, a needle is placed intra-articularly in the proposed portal location before the skin incision. To avoid injury to the underlying sensory branches, [39] it is helpful to use the thumb to pull the skin against the tip of a No. 11 blade, which helps ensure that only the skin is incised. The cannula with the blunt trocar should be placed at a 30-40° angle and pointed proximally to allow the cannula to enter in line with the articular surfaces.
The midcarpal portals are made approximately 1 cm distal to the 3-4 and 4-5 portals. [40, 41] The midcarpal space is tighter than the radiocarpal space; therefore, care must be taken when the blunt trocar enters this space. Once the midcarpal trocar sheaths have been placed, they should be maintained; some extravasation will occur, which makes reintroduction difficult.
The 3-4 portal is the primary viewing portal. The 4-5 or 6-R portal is the main working portal. The 6-U portal is usually the inflow portal, and outflow is generally through the arthroscopic cannula. To assist with outflow drainage, intravenous extension tubing is connected to the cannula and drains into a basin.
Preprocedural Evaluation
The wrist should be examined in a systematic pattern, often beginning with the radial side of the wrist. The proximal aspect of the scaphoid and radial styloid process can be examined for osteoarthritic changes or synovitis. With ulnar translation, the volar extrinsic ligaments are observed, with the radioscaphocapitate ligament and the adjacent long radiolunate identified first. [42, 43, 44]
The long radiolunate ligament is an extremely wide structure that is usually two or three times the width of the radioscaphocapitate ligament (see the image below). [45, 46]
Arthroscopic image of the radial radiocarpal joint. The radioscaphocapitate ligament is the most volar radial extrinsic wrist ligament. Adjacent and ulnar to the radioscaphocapitate ligament, the long radiolunate ligament is depicted. Note that the long radiolunate ligament is larger. The scaphoid is depicted above.
The short radiolunate ligament is ulnar to the long radiolunate ligament and appears as a vascularized tuft without any distinguishing architecture (see the image below). Blood vessels are frequently noted along the ligament. The intrinsic scapholunate ligament is distal to the short radiolunate ligament and generally has a slight concave shape due to the normal curvature at the scapholunate junction. Also, the intrinsic scapholunate ligament has a membranous proximal portion that progresses to a thicker dorsal portion.
The short radiolunate ligament appears as a vascularized tuft. It is ulnar to the long radiolunate ligament.
The surgeon follows the radiocarpal joint along the lunate fossa of the distal aspect of the radius to the junction of the distal part of the radius, at the ulnar aspect and the articular disc of the TFCC. A probe is drawn across the disc—which should be fairly taut, similar to a trampoline—and a ballottement of the disc is performed with the probe. This is known as the trampoline test (see the image below).
Trampoline test. Similar to a trampoline, the disc of the triangular fibrocartilage complex should be taut when probed.
If the trampoline test results in the disc being floppy and floating without tension, a tear in the peripheral or central portion of the TFCC must be suspected. (The ulnar styloid recess can be mistaken for a peripheral tear, but this is actually a normal anatomic finding.)
The lunotriquetral interosseous ligaments and ulnocarpal ligaments are best observed by placing the arthroscope in the 4-5 or 6-U portal. The ulnolunate and ulnotriquetral ligaments are observed as capsular thickenings in the volar aspect of the ulnar capsule (see the image below).
Lunotriquetral ligament, as depicted from the 4-5 portal in the radiocarpal space.
After the radiocarpal joint is evaluated, the midcarpal joint is examined. [47] The arthroscope is usually placed in the radial midcarpal space. In small wrists, the arthroscope may be more easily placed in the ulnar midcarpal portal. After the midcarpal space is entered, the concave curvature of the capitate head is noted distally.
On a proximal view, the scapholunate joint (on the radial aspect) and the lunotriquetral joint (on the ulnar aspect) can be identified. Both joints should be probed to ensure that no instability exists. The scaphotrapeziotrapezoid joint can be observed by passing the arthroscope radially. If the arthroscope is moved completely ulnarly, the capitate-hamate joint can also be observed. If midcarpal instability is present, the amount of capsule on the volar aspect between the hamate and triquetrum is greater than normal.
Löw et al studied the use of long and short videos of the radiocarpal and the midcarpal joints to determine whether there was a relation between video length and interobserver reliability. [48] They found that ligament lesions were more accurately evaluated on long videos than on short ones. Their recommendation was that the video sequence of the radiocarpal joint should last about 60 seconds and that of a midcarpal joint should last about 45 seconds, with videos of difficult joints to last longer.
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Traction tower after draping.
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The wrist is suspended in the traction tower, and the portals are drawn with the associated landmarks on the extensor surface of the wrist.
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The wrist is suspended in the traction tower, and the portals are drawn with the associated landmarks on the extensor surface of the wrist.
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Arthroscopic image of the radial radiocarpal joint. The radioscaphocapitate ligament is the most volar radial extrinsic wrist ligament. Adjacent and ulnar to the radioscaphocapitate ligament, the long radiolunate ligament is depicted. Note that the long radiolunate ligament is larger. The scaphoid is depicted above.
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The short radiolunate ligament appears as a vascularized tuft. It is ulnar to the long radiolunate ligament.
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Trampoline test. Similar to a trampoline, the disc of the triangular fibrocartilage complex should be taut when probed.
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Lunotriquetral ligament, as depicted from the 4-5 portal in the radiocarpal space.
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Grade III scapholunate tear, as depicted from the midcarpal space. Note that the gap allows passage of a 1-mm probe.
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Grade IV scapholunate tear, as depicted from the midcarpal space. A 2.7-mm arthroscope may be freely passed through the tear.
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Posteroanterior radiograph of a wrist. Abnormal widening between the scaphoid and lunate is present, indicating a complete scapholunate tear.
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Electrothermal shrinkage performed in a patient with dynamic carpal instability. Careful use of the probe is required to avoid damage to critical structures.
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Class IA tear of the triangular fibrocartilage complex. The probe points at the tear.
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Arthroscopic debridement in a class IA tear. The flap has been debrided, and the arthroscope is used to smooth the remaining disc.
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Class 1B tear, as depicted from the 3-4 portal. Reactive synovitis may cover the tear.
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Repair of a class IB tear with the outside-in technique. A small, longitudinal incision incorporates the 6-R portal.
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Arthroscopic image of a cannulated needle piercing the articular disc in a class IB repair.
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Arthroscopic view reveals retrieval of the suture with a small joint grasper.
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Sutures placed before being tied in a class IB tear.
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Class ID tear. Avulsion of the disc from the sigmoid notch is depicted.
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Arthroscopic image of the rim of the sigmoid notch, which is debrided to a bleeding bone bed before reattachment of the disc.
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Class IIC tear of the triangular fibrocartilage complex. Note the chondromalacia of the ulna.
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Radiocarpal view after arthroscopic removal of the ganglion stalk.
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Arthroscopic view demonstrating the articular step-off in a distal radius fracture. Hematoma and debris are removed for optimal visualization.
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Radiograph of a wrist after arthroscopic-assisted pinning of an intra-articular distal radius fracture
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Before the scaphoid is pinned, the wrist is flexed at 45 degrees, which places the scaphoid in 90 degrees flexion.
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Fluoroscopic image demonstrates reaming of the scaphoid in a proximal-to-distal fashion after arthroscopic reduction and percutaneous pinning.
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Anteroposterior radiograph after reduction and fixation with a headless screw.
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Lateral radiograph after reduction and fixation with a headless screw.
Tables
Grade |
Description |
Management |
I |
Attenuation and/or hemorrhage of the interosseous ligament as observed from the radiocarpal joint. No incongruence of carpal alignment in midcarpal space. |
Immobilization |
II |
Attenuation and/or hemorrhage of the interosseous ligament, as observed from the radiocarpal joint. Incongruence and/or stepoff, as observed from the midcarpal space. A slight gap (less than the width of a probe) between the carpals may be present. |
Arthroscopic reduction and pinning |
III |
Incongruence and/or stepoff of the carpal alignment are observed in both the radiocarpal and midcarpal space. The probe may be passed through a gap between the carpals. |
Arthroscopic reduction and/or open reduction and pinning |
IV |
Incongruence and/or stepoff of the carpal alignment are observed in both the radiocarpal and midcarpal space. Gross instability with manipulation is noted. A 2.7-mm arthroscope may be passed through the gap between the carpals. |
Open reduction and repair |
