Rationale and Basic Science Pertinent to the Procedure

Scapholunate dissociation is the most frequently diagnosed pattern of carpal instability.¹ If left untreated, it leads to scapholunate advanced collapse and progressive painful arthritis of the wrist.² Treatment for scapholunate dissociation remains controversial and has varied from limited wrist arthrodeses^3–6 to soft tissue procedures, including dorsal capsulodesis^7–11 and scapholunate interosseous ligament reconstruction using tendon graft.^12–14

Soft tissue reconstructions have several theoretical advantages that make them attractive alternatives to other procedures. In contrast to arthrodeses, soft tissue reconstructions preserve more intercarpal motion, including scaphoid flexion and extension with radial and ulnar wrist deviation. Arthrodeses limit motion. The scaphotrapeziotrapezoid limited arthrodesis results in a loss of 16% to 45% of wrist flexion, 25% of wrist extension, and 45% of radial deviation.^3–6 Scaphocapitate arthrodesis, also advocated for scapholunate dissociations, has been shown to produce similar reductions in wrist range of motion and in relative intercarpal motion to scaphotrapeziotrapezoid arthrodesis.¹⁵ There has been a renewed interest in tendon reconstructions^12,14; however, historically early results, although promising, have not stood the test of time.¹³

With a dorsal capsulodesis procedure, which is a soft tissue procedure rather than an arthrodesis, greater intercarpal motion is preserved, including scaphoid flexion and extension with radial and ulnar wrist deviation. Blatt⁷ popularized the capsulodesis using a radius-based flap of wrist capsule inserted into the distal pole of the scaphoid. That procedure has been reported to result in a significant decrease in wrist flexion by some investigators, however, including Blatt, who reported a mean loss of 20 degrees of flexion.^7,16 Although it corrects the flexed posture of the scaphoid by crossing the radiocarpal joint and tethering the scaphoid, it nevertheless fails to correct the diastasis between the scaphoid and lunate seen radiographically.

Seeking to address these problems, we developed the dorsal intercarpal ligament capsulodesis (DILC) for the treatment of scapholunate dissociation based on the dorsal intercarpal ligament of the wrist. In a cadaver model, we tested our hypothesis that the DILC can restore the scapholunate relationship with improved wrist range of motion and function.¹⁷ In our model, the scapholunate interosseous ligament was sectioned, and the results of the DILC were compared with the results of a Blatt capsulodesis.¹⁷ To perform the capsulodesis using the dorsal intercarpal ligament, a 5-mm strip of the portion of the ligament that inserts onto the trapezoid was dissected free. The dorsal intercarpal ligament has some fibers that insert onto the dorsal ridge of the scaphoid, but none that insert onto the distal pole of the scaphoid; the remainder of the ligament inserts onto the trapezoid. The scaphoid and lunate were reduced anatomically. The prepared dorsal intercarpal ligament was rotated proximally on its origin from the triquetrum, stretched as tightly as possible, and held in position with a forceps. The ligament was secured to the distal pole of the scaphoid with a suture anchor (Figs. 48-1 and 48-2).

FIGURE 48-1 A and B, Dorsal intercarpal ligament capsulodesis from a dorsal perspective. The dorsal intercarpal ligament is elevated from its insertion on the trapezium and trapezoid (A), rotated proximally, and secured to a previously prepared bony trough in the distal pole of the scaphoid (B) using a suture anchor and additional nonabsorbable sutures as needed.

(From Szabo RM, Slater RR Jr, Palumbo CF, et al: Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: clinical results. J Hand Surg [Am]. 2002; 27:978-984.)

FIGURE 48-2 A and B, Dorsal intercarpal ligament capsulodesis from a lateral perspective. A, After the dorsal intercarpal ligament is elevated, the scaphoid is rotated back into normal alignment with the trapezium. B, The completed ligament transfer is shown. The soft tissue reconstruction is reinforced with Kirschner wires for the first 8 weeks after surgery.

(From Szabo RM, Slater RR Jr, Palumbo CF, et al: Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: clinical results. J Hand Surg [Am]. 2002; 27:978-984.)

DILC restored the normal scapholunate relationship more completely than did a Blatt capsulodesis. After a Blatt capsulodesis, the scapholunate diastasis remained significantly increased (P < .05) compared with the intact specimens when the wrist was placed in radial deviation, ulnar deviation, and the clenched fist position. In contrast, there were no significant differences in scapholunate gap between the intact specimens and DILC in any wrist position. In addition to the differences seen when comparing the intact group with each reconstructed group, there were significant differences between the two reconstructed groups. In the clenched fist position, in which the repair is stressed maximally, there was a significant increase in the scapholunate diastasis measured after a Blatt capsulodesis compared with DILC (5.8 ± 1.07 mm versus 3.1 ± 1.03 mm; P < .05). Similar significant differences were noted between reconstruction methods when the wrist was in extension and radial deviation. Both reconstruction techniques reduced the scapholunate angle. The scapholunate angle decreased more after DILC than after Blatt capsulodesis in all conditions except flexion, in which they were equal; however, the differences were not statistically significant owing to lack of power of the study.

Indications

DILC has a role in the treatment of dynamic scapholunate instability and flexible chronic static scapholunate dissociation in the absence of arthritic changes. The procedure also is useful as an augmentation for patients with an acute perilunate dislocation undergoing open reduction and repair of the scapholunate interosseous ligament.

With regards to age range, the procedure has no limitations. It is our preferred choice in skeletally immature individuals with scapholunate instability because growth should not be disturbed. DILC can be done in the acute setting because raising the dorsal intercarpal ligament based ulnarly provides a good exposure to repair the scapholunate interosseous ligament if needed. DILC can be done anytime in the chronic setting. There are no time limits for the procedure.

Contraindications

DILC is absolutely contraindicated in patients with irreducible (inflexible) chronic static scapholunate dissociation and in patients with any arthritic changes indicative of a scapholunate advanced collapse wrist. This procedure is not indicated for patients with chronic, static scapholunate gaps of 1 cm or greater.

The procedure may be relatively contraindicated in patients who require high demand of wrist strength as judged by the physician and patient. These patients may be best served by a scaphocapitate or scaphotrapeziotrapezoid arthrodesis, although those procedures also have not provided a predictable solution to this problem.^3,4

Surgical Technique

A longitudinal skin incision is made dorsally over the patient’s wrist, centered over Lister’s tubercle. The superficial soft tissues are dissected off the extensor retinaculum, being careful to avoid injuring the cutaneous branches of the ulnar and radial nerves. The extensor pollicis longus is unroofed by incising the retinaculum over the third extensor compartment in a step-cut fashion to facilitate subsequent closure, and the tendon is retracted radially. A surgical sponge is used to wipe the dorsal ligamentous and capsular structures clean so that the interval between the dorsal radiocarpal and the dorsal intercarpal ligament can be identified in line with the long finger. An umbilical tape is passed around the dorsal intercarpal ligament, which is dissected out as it traverses the operative field (Fig. 48-3). It is then divided off its insertion on the trapezoid and trapezium (Fig. 48-4). A 5-mm-wide strip of the ligament is harvested and reflected ulnarly, exposing the scaphocapitate and scaphotrapeziotrapezoid joints (Fig. 48-5).

FIGURE 48-3 The dorsal intercarpal ligament is dissected and tagged with an umbilical tape. This ligament is a stout structure to be differentiated from capsular tissue. Arrow points to origin on the triquetrum.

FIGURE 48-4 A hemostat is beneath the dorsal intercarpal ligament, which is being released from its insertion on the trapezium and trapezoid (arrow).

FIGURE 48-5 The dorsal intercarpal ligament is reflected ulnarly (thick arrow).The scapholunate diastasis is being shown with a laminar spreader. The scaphoid (dashed arrow) is flexed almost 90 degrees.

Care is taken not to injure the vascular pedicle entering the scaphoid at its dorsal ridge. Next, the dorsal wrist capsule is incised longitudinally over the joint, and the dissection is continued proximally and subperiosteally beneath the second and fourth extensor compartments as necessary to allow adequate exposure.

To facilitate the actual reduction of the scaphoid and lunate, two 0.045-inch Kirschner wires (K-wires) are drilled in the posteroanterior direction to use as controlling joysticks—one in the scaphoid proximal pole and one in the lunate. The bones are reduced into normal anatomical alignment by extending the scaphoid and flexing the lunate and compressing them in the radial-ulnar direction. While maintaining the reduction, one or two parallel 0.045-inch K-wires are drilled percutaneously through the scaphoid into the lunate, and an additional 0.045-inch K-wire is drilled across the distal pole of the scaphoid into the capitate.

Appropriate reduction and wire placement are confirmed by direct inspection and intraoperative fluoroscopy. Particular attention is paid to the scapholunate gap on the anteroposterior view, the scapholunate angle on the lateral view, and the alignment of the distal scaphoid and the trapezium on the lateral view (Fig. 48-6). The remnant of the scapholunate interosseous ligament is reattached when possible using 4-0 nonabsorbable sutures via drill holes in a roughened spot in the dorsal proximal pole of the scaphoid, or alternatively via a small suture anchor.

FIGURE 48-6 A and B, Postreduction x-rays illustrating the position of the suture anchor in the distal pole of the scaphoid, two Kirschner wires across the scapholunate joint, and one Kirschner wire across the scaphocapitate joint. A, Anteroposterior view. B, Lateral view. Restoration of the scapholunate angle must be confirmed on this view.

A bony trough is prepared on the dorsal surface of the distal pole of the scaphoid adjacent to the scaphotrapezial joint, well distal to the scaphoid’s axis of rotation. A mini-Statack suture anchor (Zimmer, Inc., Warsaw, IN) attached to a 2-0 braided polyester suture is drilled into place at the base of the trough. One end of the suture anchor is passed through the end of the dorsal intercarpal ligament and then brought back out creating a Krackow stitch,¹⁸ which is tied securely to bring the ligament firmly and snugly down into the trough on the scaphoid. Additional 4-0 nonabsorbable sutures are used to secure further the transferred ligament to its new insertion. The capsule is closed over the scapholunate interval, the extensor pollicis longus is replaced in its compartment, and the retinaculum is closed over the extensor tendons. The skin is closed in routine fashion.

Postoperatively, the extremity is immobilized in a bulky thumb spica dressing that extends above the elbow, reinforced with plaster splints. After 8 to 10 days, the sutures are removed, and the dressing is changed to a thumb spica cast extending above the elbow for 3 weeks followed by a below-elbow thumb spica cast for an additional 4 weeks. The K-wires are removed 8 weeks after surgery, at which time gentle range of motion exercises under supervision are begun; a removable protective splint is worn between exercise sessions. Immobilization is discontinued 3 months after surgery. Patients are instructed to avoid forceful axial loading of the wrist, particularly in extension, such as with weightlifting or pushups, for 6 months after surgery.

Practical Tips

It is important to identify clearly the dorsal intercarpal ligament from surrounding capsular tissue. Rubbing the dorsal structures from medial to lateral with gauze helps with this visualization. It also is acceptable to leave some of the fibers of the dorsal intercarpal ligament that are attached to the scaphoid and just use the distal portion to advance.

Potential Pitfalls

Failure to reduce the scapholunate gap and correct the scapholunate angle would lead to carpal collapse. Using this procedure on patients with established arthritis would lead to continued pain. It is a good idea to inspect the radiocarpal joint at the time of surgery and have an alternative plan if arthritis is found. Care should be taken to ensure that suture anchors are secure and placed completely subchondral so that they do not erode cartilage.

Controversies

Although we were encouraged from biomechanical studies and early clinical follow-up of the DILC, we noted that many other soft tissue capsulodesis techniques were reportedly successful at 1- or 2-year follow-up. Moran and associates¹¹ reviewed their intermediate-term results (average 54 months) after Blatt or Mayo capsulodesis, and noted that the results of their capsulodesis did not hold up over time. Although dorsal capsulodesis provided pain relief for patients with dynamic and static scapholunate instability, it did not provide maintenance of radiographic carpal alignment in cases of chronic scapholunate dissociation.¹¹ It remains controversial whether soft tissue procedures or limited arthrodesis is better. Zarkadas and colleagues¹⁹ performed a study to evaluate the practice pattern of specialized hand surgeons in the management of acute and chronic scapholunate instability. They mailed a survey to the 1628 members of the American and Canadian Societies for Surgery of the Hand and received 468 responses from hand surgeons. The study showed that the management of chronic scapholunate instability varied greatly among the respondents. Favored management of chronic scapholunate dissociation included the Blatt capsulodesis alone, capsulodesis combined with a scapholunate ligament repair, or scaphotrapeziotrapezoid arthrodesis.¹⁹ Treatment of chronic scapholunate dissociation remains an unsolved problem.

Complications

Complications are related to the K-wires used for fixation in this procedure. Some patients have irritation of the soft tissue surrounding the pins. Occasionally, patients present with pain and erythema around the pins and are treated with oral antibiotics prophylactically. With early pin loosening, there can be a loss of reduction.

Results

Previous studies have reported good clinical results using a dorsal capsulodesis to treat static scapholunate instability. Blatt⁷ reported good results in 12 patients and a mean recovery of 80% of grip strength. Lavernia and colleagues⁸ reported good results in 17 of 21 patients treated with scapholunate interosseous ligament repair combined with a dorsal capsulodesis procedure. Wintman and coworkers¹⁶ showed that dorsal capsulodesis also can be used effectively to treat dynamic scapholunate instability. In a series of 20 procedures in 19 patients, subjective and objective evaluations improved substantially after surgery. After surgery, the symptoms of pain and clunking decreased significantly. Functional status was improved, most strikingly in the tasks of opening jars, sweeping, shoveling, and throwing. The investigators noted a meaningful improvement in wrist stability determined by the scaphoid shift maneuver.

One problem with these previously described procedures is that they limit wrist motion, particularly flexion, because the transferred capsule tethers the distal pole of the scaphoid to the distal radius. In Blatt’s series,⁷ loss of wrist flexion averaged 20 degrees. In the series reported by Lavernia and coworkers,⁸ mean loss of flexion was 17 degrees. Wintman and colleagues¹⁶ reported a mean loss of 12 degrees of flexion. In addition, none of the described procedures were successful at decreasing the scapholunate gap directly.

DILC conceptually has certain advantages over other soft tissue techniques. Because it links the triquetrum to the distal pole of the scaphoid directly, DILC seems to keep the proximal carpal row linked together to function as a unit. Our cadaver study confirmed that DILC decreased the scapholunate diastasis better than a Blatt capsulodesis, even when maximally loaded in the clenched fist position. We believe that the direction of the soft tissue tether in DILC may partly or entirely account for the observed decreased diastasis. We also believe that with DILC, the reduction of the scapholunate angle is accomplished in part because the transferred dorsal intercarpal ligament rests over the proximal pole of the capitate, which acts as a pulley to support the ligament and prevent the distal pole of the scaphoid from flexing excessively. DILC links the proximal carpal row together to decrease the scapholunate diastasis that develops after scapholunate interosseous ligament disruption. It decreases the diastasis better than a Blatt capsulodesis, and it corrects the scapholunate angle equally well. Neither DILC nor the Blatt capsulodesis restores normal wrist mechanics completely. The finding that DILC was strong enough to restore scapholunate gap and angle to near-normal conditions, even with loads applied across the wrist, was encouraging enough for us to start offering this procedure to patients.

We reported the results of a prospective study of 21 patients (22 wrists), 16 to 62 years old, followed 1 to 4 years.¹⁰ For this study, all patients returned to complete a questionnaire and have a physical examination performed by physicians and therapists independent of the treating surgeons, and to obtain standardized radiographs of the wrists. Patient demographics, mechanism of injury, range of motion, and grip strength were recorded. Patients completed the Mayo wrist, Short-Form-12, and Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaires. The scapholunate angle improved significantly (P < .01) from a mean preoperative value of 65 degrees to 54 degrees immediately postoperatively and remained at 50 degrees at final follow-up (P < .01). The scapholunate gap improved significantly from a mean preoperative value of 4.5 mm to 2.6 mm immediately postoperatively and remained at 2.7 mm at final follow-up (P < .01). There was no significant change in grip strength. Wrist flexion decreased by 10% postoperatively compared with a 15% decrease in wrist extension. Radial deviation decreased by 20%, whereas ulnar deviation decreased by 11% postoperatively.

Patients were satisfied with the outcomes. The mean DASH score for this group of patients was 17 (SD 17, range 1 to 69). The mean SF-12 score was 83 (SD 21, range 14 to 100). Two patients scored below the national mean of 50. The mean Mayo wrist score was 77 (SD 15, range 50 to 95). There were five excellent, seven good, five fair, and five poor results according to Mayo wrist scores. The DASH and the SF-12 score did not correlate with the Mayo wrist score, postoperative grip strength, or postoperative range of motion.

Our results confirmed that our hypothesis shown in vitro actually occurred in vivo. The scapholunate angle and diastasis were reduced and maintained over the duration of follow-up in this study. Longer follow-up is warranted, however, to see if this outcome is permanent. We are starting to see patients after 5 years show radiographic deterioration, although clinically they appear better than their x-rays. We continue to monitor our patients for longer term follow-up.