General Information

Shrinkage requires very low energy settings. The radiofrequency (RF) devices must be adjusted to heat the tissue to a temperature of 65°C to 75°C. It is wise to start at low energy and slowly increase the energy output until the desired shrinkage is observed. If a laser is used, it should be set to very low energy (i.e., 0.2 to 0.5 J at 15 pulses per second [3 to 7.5 W]). The laser is held away from the target ligament and slowly advanced until the ligament is seen to shrink. When the shrinkage has stopped, continued heating further weakens the ligament only without increasing the shrinkage. The color of the ligament changes from white to light yellow during the shrinkage. Lu and associates⁵ suggested that a cross-hatching shrinkage pattern optimizes the ingrowth of healthy tissue and hastens the recovery of the ligament. During the shrinkage, the traction on the wrist should be reduced as much as possible to permit optimal shrinkage.

Scapholunate Instability

Capsular shrinkage can be used to treat mild forms of scapholunate instability. Patients with symptomatic Geissler grade 1 and 2 scapholunate and mild midcarpal instability would be considered good candidates. Greater degrees of carpal instability associated with disruption or severe attenuation of the interosseous ligaments would not respond to capsular shrinkage.

The question is what should or can be shrunk to stabilize the scapholunate axis? The scapholunate interosseous ligament is a heterogeneous structure. Its central portion is composed of fibrocartilage, which is not shrinkable (Fig. W6-4). The dorsal and palmar portions of the scapholunate ligament are composed of type I collagen and are shrinkable (Fig. W6-5). The arthroscope and thermal wand can be placed in either the 3,4 or 4,5 portals. The 70-degree side-firing laser probe and 90-degree RF probe can be placed in the 4,5 portal, while the scope is placed in the 3,4 portal. If the 0-degree probes are used, the scope should be placed in the 4,5 portal, while the wand is passed through the 3,4 portal. Extreme caution is exercised to avoid injury to normal hyaline cartilage. Good fluid inflow and outflow are crucial because the arthroscopy fluid removes the excess thermal energy generated by the probes.

FIGURE W6-4 Histology of central fibrocartilaginous portion of the scapholunate ligament.

(From Berger RA: Ligament anatomy. In Cooney WP, Lilnscheid RL, Dobyns JH, eds: The Wrist: Diagnosis and Operative Treatment. St. Louis: Mosby, 1998.)

FIGURE W6-5 Histology of capsule showing loose collagen (CF) in a fibrous stratum (FS).

(From Berger RA: Ligament anatomy. In Cooney WP, Lilnscheid RL, Dobyns JH, eds: The Wrist: Diagnosis and Operative Treatment. St. Louis: Mosby, 1998.)

Capsular shrinkage of the dorsal intercarpal ligament could potentially reinforce the stabilizing effect of scapholunate ligament shrinkage. The dorsal intercarpal ligament is attached to the distal dorsal aspect of the scaphoid and the dorsal triquetrum (Fig. W6-6).^6,7 Shrinkage of this ligament could simulate the tensioning of this ligament noted during open capsulodesis.⁸ To accomplish this, the scope and laser/RF angled probes would be placed in the radial and ulnar midcarpal portals. Alternatively, the scope can be placed in the midcarpal joint via the radial midcarpal volar portal described by Slutsky,⁹ while the thermal probes are passed through the ulnar midcarpal portal.

FIGURE W6-6 Dorsal intercarpal ligament.

Lunotriquetral and Ulnocarpal Instability

Lunotriquetral instability is the manifestation of a spectrum of pathology. The following are three possible lunotriquetral instability scenarios:

Scenarios 1 and 2 lend themselves to capsular shrinkage because the integrity of the lunotriquetral stabilizers, although compromised, is maintained. Shrinkage in scenario 3 would be ineffective because of the extensive disruption of the lunotriquetral stabilizers.

Mild forms of lunotriquetral instability can be treated with ulnocarpal ligament shrinkage. I have applied this technique in a few cases with satisfying results. This procedure takes advantage of the anatomy of the ulnotriquetral and ulnolunate ligaments. These ligaments form a “V” as they diverge from their origin on the palmar distal radioulnar ligament and insert on the palmar aspect of the lunate or triquetrum (Fig. W6-7). As the ligaments are shrunk, the arms of the “V” shorten and approximate the lunate to the triquetrum, stabilizing the lunotriquetral joint. This stabilization can be reinforced further with the shrinkage of the lunotriquetral interosseous ligament. The lunotriquetral ligament histology is similar to that of the scapholunate ligament and can undergo dorsal and palmar, but not central, shrinkage. Isolated ulnocarpal ligament instability also can be treated with ulnocarpal ligament shrinkage. Ulnocarpal shrinkage is accomplished with the arthroscope in the 3,4 portal and the laser in the 4,5 or 6U portals.

FIGURE W6-7 Palmar view of ulnocarpal ligaments showing “V” configuration.

Midcarpal Instability

It is tempting to apply capsular shrinkage to the treatment of midcarpal instability. Midcarpal instability is associated with attenuation of the ulnar arcuate ligament, triquetrohamate ligament, dorsal intercarpal ligament, and dorsal radiocarpal ligaments. All of these ligaments can be shrunk. To access the ulnar arcuate ligament and triquetrohamate ligament, the arthroscope would be placed in the radial midcarpal portal, while the zero-degree laser/RF probe would be placed in the ulnar midcarpal portal. To access the fibers of the dorsal radiocarpal and dorsal intercarpal ligaments, the angled laser/RF probes are placed in the ulnar midcarpal portal.