Approach Considerations
Although the diagnosis of wrist instability has been known for decades, the treatment of wrist instability remains a hotly debated topic among hand surgeons. Such treatment is necessarily complex and is usually specific to the type of instability present. A full, detailed review of all of the available treatment options is beyond the scope of this article. To simplify the discussion, treatment is summarized below under the headings of the following specific types of instabilities:
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Scapholunate instability
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Lunotriquetral instability
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Midcarpal instability
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Ulnar translocation
Surgical Therapy
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. [50, 51] Partial tears of the scapholunate interosseous ligament (SLIL) are thought to represent occult or predynamic instability. [24, 52] For these injuries, most recommend an initial trial of splinting, casting, or both. [52, 53] Arthroscopic debridement with or without pinning can be an option in these patients in whom initial conservative treatment is unsuccessful. [54, 55]
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 a significant scapholunate diastasis on static or dynamic radiography.
With complete SLIL tears, cast immobilization does not reduce or prevent scapholunate diastasis. [52] Significant force occurs at the scapholunate interval on wrist loading. Options for acute management of these tears include the following:
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Direct repair with or without dorsal capsulodesis
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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 dorsal intercalated-segment instability [DISI]). [54, 55] 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. [56]
In a study involving 17 patients with chronic scapholunate instability (average duration, 9.5 mo), 13 of whom had a DISI deformity, Ho et al described an arthroscopy-assisted minimally invasive approach to repair of both the dorsal SLIL component and the volar component. [57] At an average follow-up of 48.3 months, 13 patients had returned to their preinjury job level, 11 had no wrist pain, and six had some pain on either maximum exertion or at the extreme of motion. There were no major complications, and all of the patients were satisfied with the operation and its outcome.
Most reconstructive wrist surgeons recommend direct repair for acute (< 6 wk) tears if a sufficient SLIL remnant is present. [52, 58] Lavernia et al reported on dorsal capsulodesis to augment a direct repair and demonstrated good results in 81% of their patients. [59] Satisfactory results were seen even as long as 3 years after injury.
In patients with an unrepairable SLIL but 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. [60] 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.
Other techniques attempt to avoid limitation of flexion by not tethering the scaphoid to the radius. [61, 62] Several such techniques have been described. As Berger et al initially proposed, [20] 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 the image below). Slater et al used a portion of the dorsal intercarpal ligament that attaches to the distal scaphoid and trapezoid and reinserted it to the distal pole of scaphoid tuberosity. [62] 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 does.
Mayo dorsal intercarpal (DIC) capsulodesis. Copyright Mayo Clinic, used with permission of Mayo Foundation.
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. [52]
Techniques for this approach involve either a tendon to reconstruct the SLIL or a bone-ligament-bone construct. [52, 63, 64, 65, 66] 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 showed promise. [64] Their technique used a strip of the flexor carpi radialis (FCR) and wove it through the scaphoid. The tendon was 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. [52]
Fusions that have been described involve the scaphocapitolunate, [67] the scaphotrapezial trapezoid, [27, 68, 69, 70, 71] the scaphocapitate, [72] and the scapholunate. [73] 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. [74]
For studies of other techniques, see Garcia-Elias [75] , Ogunro [76] , Short [77] , and Danoff. [78]
When arthritic change (advanced scapholunate collapse) or a wide, irreducible scapholunate gap is present, options include proximal-row carpectomy or scaphoid excision and fusion of the lunate, triquetrum, capitate, and hamate (four-corner fusion). Significant degenerative changes at the proximal hamate or of the lunate fossa are a contraindication for 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. The treatment algorithm can probably be based on the type and age of the injury. A partial tear of the lunotriquetral interosseous ligament (LTIL) may be clinically suspected and should not have the associated volar intercalated-segment instability (VISI) deformity. Reagan et al recommended a period of immobilization for acute injuries. [28] Others have recommended arthroscopic evaluation and percutaneous pinning. [16]
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. [28] 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. [16]
For patients who present late after their initial injury, surgical management includes the following:
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Capsulodesis
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Ligament reconstruction
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Arthrodesis
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Ulnar shortening
Shin et al described a ligament reconstruction that used a distally based strip of the extensor carpi ulnaris tendon. [79] Pillukat et al found this approach to yield a high percentage of good-to-excellent results, with only rare complications. [80]
Because some patients with symptomatic lunotriquetral instability also have ulnar impaction syndrome, Ruby treated these patients with chronic lunotriquetral tears with ulnar shortening alone, especially if they have positive or neutral ulnar variance. [16] Ulnar shortening is believed to tighten the volar ulnotriquetral and ulnolunate ligaments, thereby 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 the 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. [81] Three patients (27%) had persistent pain, and the 11 patients achieved a postoperative grip strength of only 59% as compared with the uninjured side.
Kirschenbaum et al reported results after lunotriquetral fusion that were slightly better. [82] Among 14 patients, only one had persistent pain, and the average grip strength was 94% as compared with the contralateral side. In two patients, fusion did not occur: One underwent repeat fusion, whereas the other was not symptomatic. Wrist motion was also well preserved in this series: about 80-85% as compared with the uninjured wrist.
The results of these two studies notwithstanding, others authors have reported nonunion rates as high as 57%, persistent pain in 52%, and decreased in wrist motion in 31%. [83]
Instead of lunotriquetral fusion, some authorities have recommended lunotriquetrohamate [33] or triquetrohamate [15] 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 result on fluoroscopic dorsal-displacement stress testing. [17] 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 six of the limited midcarpal arthrodeses were successful, whereas six of the nine soft-tissue reconstructions failed. [13]
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.
Chaudhry et al described a soft-tissue stabilization technique using a palmaris longus graft in six patients (seven wrists) with palmar midcarpal instability. [84] They achieved good medium-term results in most cases; the procedure retained some midcarpal mobility, eliminated "clunking" in most patients, and provided a noteworthy improvement in grip strength and function. Further evaluation in larger studies with a longer follow-up would be required to assess the value of this approach.
In a study of 23 consecutive patients (12 male, 11 female; average age, 27 y) with 27 symptomatic wrists, von Schroeder treated midcarpal instability with an initial 6 weeks of full immobilization followed, in cases of recurrence, by plication of the dorsal capsule and extrinsic ligaments to stabilize the midcarpal joint; if plication failed, four-corner intercarpal arthrodesis was performed (n = 2). [85] All patients had less pain at final follow-up. Female patients younger than 25 years with hypermobility and without major traumatic or work-related injuries had the greatest improvements; outcomes were poorer in men older than 25 years with moderate or severe trauma (mostly work-related).
Ulnar translocation
In the rheumatoid wrist, ulnar translocation is usually effectively treated with radiolunate fusion. [86] Significant arthritis at the radioscaphoid joint may also require radioscaphoid fusion. Total wrist fusion is probably the best option if significant midcarpal arthrosis is present as well.
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(Click image to enlarge.) Dorsal carpal ligaments. Copyright Mayo Clinic, used with permission of Mayo Foundation.
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(Click image to enlarge.) Volar carpal ligaments. Copyright Mayo Clinic, used with permission of the Mayo Foundation.
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The wrist is a simple link between the proximal and distal rows. The pivot point is at the center of rotation of the capitate and lunate. This joint, without other supporting structures, is stable only in tension. It is unstable in compression, as this figure depicts, and tends to collapse.
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The scaphoid acts like a bridge between the proximal and distal row and protects the link from collapsing.
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Mayfield perilunate instability pattern. Copyright Mayo Clinic, used with permission of the Mayo Foundation.
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(Click Image to enlarge.) Watson scaphoid shift test.
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(Click Image to enlarge.) Kleinman shear test.
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Reagan shuck test.
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Linscheid compression test.
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McMurty ulnar translation measurement.
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Mayo dorsal intercarpal (DIC) capsulodesis. Copyright Mayo Clinic, used with permission of Mayo Foundation.
