Carpal Ligament Instability Treatment & Management

Treatment of carpal instability is complex and usually specific to the type of instability and is certainly controversial. A full detailed review of all treatment options is beyond the scope of this article. To simplify this discussion, each treatment is summarized under specific types of instabilities: scapholunate, lunotriquetral, and midcarpal instability and also ulnar translocation.

Scapholunate instability

There is no consensus on the appropriate treatment of scapholunate instability. The treatment is usually specific to the different stages or degree of injury. Partial tears of the SLIL are thought to represent occult or predynamic instability.^{[18, 39]} For these injuries, most recommend an initial trial of splinting and/or casting.^{[39, 40]} Arthroscopic debridement with or without pinning can be an option in these patients in whom initial conservative treatment is unsuccessful.^{[41, 42]}

A complete tear of the SLIL may not by itself lead to an acute scapholunate gap or diastasis. Biomechanical studies support the concept that additional supporting ligaments must also be injured for this gap to be apparent. In addition, attenuation of these ligaments may lead to a diastasis that is observed late with respect to the initial injury date. In either case, a complete tear of the SLIL is suggested in the presence of the significant scapholunate diastasis on static or dynamic radiography.

With complete SLIL tears, cast immobilization does not reduce or prevent scapholunate diastasis.^[39] Significant force occurs at the scapholunate interval on wrist loading. Options for acute management of these tears include direct repair with or without dorsal capsulodesis or arthroscopic debridement, reduction, and pinning. Some recommend the latter treatment for acute (< 3 mo) tears that have evidence of instability on static radiography (gap < 3 mm or DISI).^{[41, 42]}

A retrospective study by Weiss et al showed that 33% of patients who underwent arthroscopic debridement, reduction, and pinning of complete SLIL tears had persistent pain and required further surgery.^[43] Most reconstructive wrist surgeons recommend direct repair for acute (< 6 wk) tears if a sufficient SLIL remnant is present.^{[39, 44]} Lavernia et al reported on dorsal capsulodesis to augment a direct repair and demonstrated good results in 81% of their patients.^[45] Satisfactory results were seen in patients, even as long as 3 years after injury.

In patients with unrepairable SLIL but with a reducible scapholunate interval and without degenerative changes, an indirect or direct ligament reconstruction has been advocated. Typically, the presentation is chronic, and the SLIL is usually not repairable. Indirect ligament reconstruction is based on stabilizing the scaphoid to prevent the rotatory subluxation that often occurs in scapholunate instability.

Some indirect ligament reconstructions also attempt to close the scapholunate gap. The most widely used indirect ligament reconstruction is the Blatt dorsal capsulodesis.^[46] This technique uses a flap of dorsal capsule to tether the scaphoid tuberosity to retard scaphoid flexion. Because the flap is attached to the distal radius, wrist flexion is significantly reduced by 20% on average.

More recent techniques attempt to avoid limitation of flexion by not tethering the scaphoid to the radius.^{[47, 48]} Several techniques have been described. As Berger et al initially proposed{Ref3} a strip of dorsal intercarpal ligament detached from the triquetrum can be used to tether the distal scaphoid pole to the lunate or radius (see image below). Slater et al described the use of a portion of the dorsal intercarpal ligament that attaches to the distal scaphoid and trapezoid and reinserts it to the distal pole of scaphoid tuberosity.^[48] These authors believe that this technique not only serves to limit scaphoid flexion but also reduces the scapholunate gap more effectively than the Blatt capsulodesis.

Direct ligament reconstruction is indicated when the SLIL is not directly repairable, when the scapholunate dissociation is reducible, and when no evidence of degenerative arthritis is observed. Some also believe that evidence of carpal instability (DISI) should be absent.^[39] Techniques for this approach involve either a tendon to reconstruct the SLIL or a bone-ligament-bone construct.^{[39, 49, 50, 51, 52]} All of these techniques have had some degree of success, but they are not universally durable. They require a long period of wrist immobilization and result in some loss of final wrist motion.

Brunelli and Brunelli described one such technique that shows promise.^[50] Their technique uses a strip of the flexor carpi radialis (FCR) and weaves it through the scaphoid. The tendon is also sutured across the scapholunate interval. Limited intercarpal fusions are indicated when carpal instability (DISI) is present without gross evidence of degenerative changes at the radiocarpal joint.^[39]

Fusions that have been described involve the scaphocapitolunate,^[53] the scaphotrapezial trapezoid,^{[21, 54, 55, 56, 57]} the scaphocapitate,^[58] and the scapholunate.^[59] Viegas et al found that the scaphocapitolunate and scapholunate fusions distributed the load more uniformly across both the scaphoid and lunate fossae than the scaphotrapezial trapezoid or scaphocapitate fusions.^[60]

For studies of new techniques, see Garcia-Elias^[61] , Ogunro^[62] , Short^[63] , and Danoff.^[64]

When arthritic change (advanced scapholunate collapse) or a wide, irreducible scapholunate gap is present, options include a proximal row carpectomy or scaphoid excision and fusion of the lunate, triquetrum, capitate, and hamate (4-corner fusion). Significant degenerative changes at the proximal hamate or of the lunate fossa are a contraindication to proximal row carpectomy. Once pancarpal arthritis involves the lunate fossa, the best surgical option may be total wrist fusion.

Lunotriquetral instability

There is no consensus on the appropriate treatment of lunotriquetral instability. Treatment algorithm can probably be based on the type and age of the injury. A partial tear of the LTIL may be clinically suspected and should not have the associated VISI deformity. Reagan et al recommend a period of immobilization for acute injuries.^[22] Others have recommended arthroscopic evaluation and percutaneous pinning.^[9]

For patients in whom conservative treatment fails, lunotriquetral dissociation direct repair with or without augmentation has been advocated. Repairing the LTIL by using an open technique to reattach it back to the site of its avulsion (usually from the triquetrum) has good results.^[22] Augmentation is usually in the form of a capsulodesis. The goal of capsulodesis is to prevent excessive flexion of the proximal row by imbricating the dorsal radiotriquetral ligament.^[9]

For patients who present late after their initial injury, surgical management includes techniques of capsulodesis, ligament reconstruction, arthrodesis, or ulnar shortening. Shin et al have described a ligament reconstruction by using a distally based strip of the extensor carpi ulnaris tendon.^[65] Because some patients with symptomatic lunotriquetral instability also have ulnar impaction syndrome, Ruby treats these patients with chronic lunotriquetral tears with ulnar shortening alone, especially if they have positive or neutral ulnar variance.^[9] Ulnar shortening is believed to tighten the volar ulnotriquetral and ulnolunate ligaments, indirectly improving lunotriquetral stability. However, this treatment may be ill advised in the patient with a VISI deformity because tightening of these volar ligaments may exacerbate their deformity.

As a treatment for lunotriquetral instability, lunotriquetral fusion is controversial. Pin et al used a compression screw and achieved fusions in all 11 patients in their study.^[66] Three patients (27%) had persistent pain, and the 11 patients achieved a postoperative grip strength of only 59% compared with the uninjured side.

Kirschenbaum et al reported results after lunotriquetral fusion that were slightly better.^[67] Among 14 patients, only 1 had persistent pain, and the average grip strength was 94% compared with the contralateral side. In 2 patients, fusion did not occur: One underwent repeat fusion, while the other was not symptomatic. Wrist motion was also well preserved in their series: about 80-85% compared with the uninjured wrist.

Despite the results of these 2 studies, others have shown nonunion rates as high as 57%, persistent pain in 52%, and decreased in wrist motion in 31%.^[68]

Instead of lunotriquetral fusion, others have recommended lunotriquetrohamate^[28] or triquetrohamate^[8] fusions. Further studies are needed to fully evaluate these fusions.

Midcarpal instability

Johnson and Carrera advocated tightening the radiocapitate ligament in patients who had a positive fluoroscopic dorsal-displacement stress test.^[10] Their technique consists of tethering the middle portion of the radiocapitate ligament to the radiotriquetral ligament to close the space of Poirier. Slight extension of the wrist is lost after this procedure.

Lichtman et al reviewed 13 patients (15 procedures) who underwent surgery for midcarpal instability over an 8-year period. They found that all 6 of the limited midcarpal arthrodeses were successful, whereas 6 of 9 soft tissue reconstructions failed.^[17]

Carpal instability that results from distal radius malunion can be effectively treated by correcting the malalignment of the radius. Opening wedge osteotomy of the radius at the location of the deformity to correct radial malalignment usually also corrects the carpal instability.

Ulnar translocation

In the rheumatoid wrist, ulnotranslocation is usually effectively treated with radiolunate fusion.^[69] Significant arthritis at the radioscaphoid joint may also require radioscaphoid fusion. Total wrist fusion is probably the best option significant midcarpal arthrosis is present as well.

Although the diagnosis of wrist instability has been present for nearly 4 decades, the treatment of wrist instability remains a hotly debated topic among hand surgeons. As a result, new and innovative methods of treatment are compared to time-tested procedures, resulting in improved understanding of wrist instability.