➢ Scapholunate reconstruction procedures are best stratified according to preoperative stages of dissociative instability, injury chronicity, and arthrosis.
➢ In general, procedures aimed at correcting scapholunate instability focus on reestablishing ligament continuity in order to normalize carpal biomechanics; however, many existing interventions have shown differential success when performed on patients with varying stages of instability and degrees of carpal malalignment.
➢ The Mayo dorsal intercarpal ligament capsulodesis has proven most effective for preserving range of motion, whereas the Blatt capsulodesis has been associated with substantial improvements in terms of the postoperative pain rating and perceived functional capacity.
Operative treatment for patients with scapholunate instability remains challenging despite the multitude of published reports on scapholunate reconstruction techniques. The management of patients who have had a failure of nonoperative treatment is complicated by a lack of consensus on instability staging and the absence of a grouped comparison of surgical outcomes. Several investigators have proposed systems to categorize scapholunate instability, most notably the algorithm devised by Garcia-Elias et al.1 According to their staging criteria, the severity of scapholunate injury, the potential for ligamentous repair, and the cartilage status should all be considered when choosing a surgical intervention; however, factors such as chronicity and preexisting joint degeneration have since emerged as major risk factors for failure of reconstruction and therefore must also be considered2. In general, procedures aimed at correcting scapholunate instability focus on reestablishing ligament continuity in order to normalize carpal biomechanics. While their objectives are similar, many existing interventions have shown differential success when performed on patients with varying stages of instability and degrees of carpal misalignment.
In the present report, we will compare the efficacies of several soft-tissue reconstruction procedures in order to stratify treatment options for scapholunate instability repair. Specifically, we will examine which procedure is most effective for particular preoperative conditions according to the Garcia-Elias classification system and will evaluate surgical techniques on the basis of the specific outcomes of range of motion, grip strength, complication rate, and postoperative pain rating.
Anatomy and Biomechanics of the Scapholunate Joint
The scapholunate joint contains the articulation of the scaphoid and lunate carpal bones. Situated between the scaphoid and the lunate is the C-shaped scapholunate interosseous ligament (SLIL), a three-part ligamentous structure that stabilizes wrist kinematics by rotating these bones during radial and ulnar deviation3 (Fig. 1).
The SLIL comprises three individual segments: dorsal, proximal, and palmar. The dorsal component of the SLIL is the strongest, crossing from the proximal pole of the scaphoid to the dorsal aspect of the lunate4. This segment has a failure force of 260 N, allowing it to resist distraction, torsional, and translational movement, and it is the least frequently involved in a partial rupture of the SLIL1. The volar segment, with a failure force of 118 N, upholds the rotational stability of the two carpal bones but remains secondary in importance to the dorsal segment of the ligament. The proximal segment is composed largely of fibrocartilage and contributes little to the prevention of abnormal scapholunate joint motion.
Pathological changes of the scaphoid and lunate may follow injury to the SLIL. Static and dynamic scapholunate instability may develop, presenting as incongruous carpal motions during wrist flexion, extension, and radioulnar deviation. Compromised SLIL integrity can also cause abnormal flexion of the scaphoid, resulting in abnormal loading through the radioscaphoid facet and subsequent arthrosis as part of a dynamic process referred to as dorsal intercarpal segment instability. In this state, the lunate loses its attachment to the scaphoid but maintains association with the radius and triquetrum via secondary ligaments, thrusting the carpal bone into abnormal extension5.
In the event that damage to a segment of the SLIL creates carpal instability, extrinsic ligaments such as the dorsal radiocarpal ligament and dorsal intercarpal ligament can compensate to stabilize the scapholunate joint. Several treatment options for scapholunate instability focus on repositioning these ancillary ligaments. As the wrist joint is capable of full rotation, undetected damage to the SLIL or its secondary ligaments may manifest as functional deficits in multiple planes. Thus, the nature of ligamentous injury and the severity of pathological changes to the scapholunate joint must be determined prior to choosing a surgical treatment.
Indications for Reconstructive Treatment and Timing of Intervention
In most cases of scapholunate injury, the aim of treatment is to arrest the degenerative process by restoring scapholunate ligament continuity and stabilizing carpal biomechanics2. It should be noted that while degradation can be slowed through surgical intervention, no procedure discussed in the present article has been shown to prevent the onset of degeneration. In order to choose an appropriate intervention, the chronicity of the injury and the stage of instability must be clearly determined. The boundaries of acute, subacute, and chronic injuries are somewhat variable; under three weeks is generally considered acute, three weeks to three months is considered subacute, and over three months is considered chronic. Patients who undergo operative treatment in the acute phase show the greatest improvement as the SLIL is still repairable6. Chronic injuries are associated with inferior results because of an irreparable SLIL and established static malalignment6.
Multiple publications have set forth suggestions for the staging of scapholunate instability1,2. Garcia-Elias et al. suggested a treatment algorithm for posttraumatic dynamic scapholunate instabilities1. They argued that aside from patient-related factors (i.e., age, health status, and vocational demands), five prognostic features must be considered when choosing treatment: the integrity of the dorsal segment of the scapholunate ligament (partial or complete tear), the potential for repair of the ligament tear, the radioscaphoid angle, the reducibility of the carpal misalignment, and the cartilage status of the radiocarpal and metacarpophalangeal joints1. Progressive inclusion of each of these five considerations advances the stage of scapholunate instability from 1 to 6. (Table I). Kitay and Wolfe proposed a five-stage modification of the Garcia-Elias scheme based on the severity of ligamentous injury and radiographic appearance, the distinction being an assertion that instability occurs in two planes of motion2. The stages of the Kitay and Wolfe system are occult, dynamic, scapholunate dissociation, dorsal intercalated segment instability, and scapholunate advanced collapse.
Of these three systems, the algorithm set forth by Garcia-Elias et al.1 has gained the most widespread recognition because of its logical sequence and the gradation of discrete stages supported by appropriate levels of evidence. Their study showed that each stage of instability can best be addressed with a particular operative treatment. In the remainder of the present report, we will compare outcomes from a comprehensive list of techniques used for scapholunate reconstruction, analyzing results in the context of the Garcia-Elias classification scheme.
Current Techniques for Scapholunate Reconstruction
The Blatt technique for dorsal capsulodesis, described in 1987, entails tethering a soft-tissue flap of dorsal wrist capsule to the distal tuberosity of the scaphoid7. As the flap attaches the scaphoid to the distal aspect of the radius, flexion undergoes a 20% reduction on average. Blatt investigated the outcomes for twelve patients who were managed with this technique for the treatment of scapholunate instability and found that range of motion and grip strength remained adequate and that the majority of patients were able to return to their preinjury work status.
Numerous studies have elaborated on the outcomes of the Blatt capsulodesis technique. In 2005, Moran et al. conducted a retrospective analysis of Mayo wrist scores8 for thirty-one patients with isolated chronic scapholunate dissociation that was classified as stage 1, 2, or 3 according to the Garcia-Elias system9. Patients with surrounding carpal injuries or radiographic evidence of arthritis were excluded from the study. Moran et al. reported a 20% decrease in wrist motion after capsulodesis (p < 0.001) and attributed the reduction to an average loss of 20° of wrist flexion. There was no significant change in grip strength after surgery, with preoperative and postoperative grip strengths being 85% and 83% of the values for the contralateral wrist, respectively. While most patients reported improvement in terms of pain, only two patients reported complete pain relief. Radiographically, the average scapholunate gap increased over time from 2.7 mm prior to surgery to 3.9 mm at the time of the latest follow-up. The average scapholunate angle increased from 55° before surgery to 62° at the time of the latest follow-up. Moran et al. also reported an average modified Mayo wrist score of 73 at the time of the latest follow-up. According to the Mayo system, scores between 65 and 79 are considered “fair,” whereas scores of ≥80 are considered “good” or “excellent.” Of the thirty-one patients in the study by Moran et al., only nine received scores of ≥80. Complications occurred in five patients (16%) and included pin-track infection (two patients), type-I chronic regional pain syndrome (two), and radial neuroma (one)9.
Lavernia et al. reported similar results in a study on fourteen patients who underwent scapholunate ligament repair combined with a dorsal capsulodesis and three patients who underwent dorsal capsulodesis alone10. The stage of instability ranged from 1 to 5 on the Garcia-Elias scale as osteoarthritis was the only exclusion criterion. The authors reported improvement in terms of grip strength, pain, and radiographic appearance, with a 12° loss of flexion over thirty-three months.
Wintman et al., in a study of seventeen patients who underwent dorsal capsulodesis for the treatment of stage-3 instability, reported decreases in the frequency (p < 0.000001), duration (p < 0.01), and severity (p < 0.0001) of pain as well as improved functional capacity at an average of thirty-four months after surgery11. Patients demonstrated an average 12° loss of wrist flexion, but no other changes in wrist range of motion or grip strength were significant.
Finally, Wyrick et al. reported insignificant improvement in terms of wrist pain and functionality in a study of seventeen patients who underwent direct scapholunate ligament repair and capsulodesis12. Preoperatively, the instability was classified as stage 4 to 6 according to the Garcia-Elias system. Dorsal capsulodesis was less effective for the patients in this study. Wrist mobility and grip strength were reduced to 60% and 71% of the values for the contralateral wrist, respectively, and no patient was pain-free within the follow-up period of thirty months. Wyrick et al. postulated that the persistence of pain in these patients was a consequence of more severe preoperative deformity; the average preoperative scapholunate angle was 78° in their study12, as compared with 62° in the study by Lavernia et al.10.
Mayo Dorsal Intercarpal Ligament Capsulodesis
Moran et al. proposed a modified version of the Blatt technique in which the proximal half of the dorsal intercarpal ligament is fixed to the dorsal aspect of the lunate after proximal rotation9. Exclusion of the radiocarpal joint allows the patient to maintain a full range of wrist flexion after surgery.
Gajendran et al. reviewed the outcomes at twenty-five and eighty-six months for fifteen patients (sixteen wrists) who underwent the Mayo dorsal intercarpal ligament capsulodesis13. The study analyzed patients with all stages of Garcia-Elias instability; a majority had chronic scapholunate dissociation, static instability, and arthritis on radiographs. However, patients showed improved scapholunate angles and unchanged grip strength, with a full range of motion of the wrist preserved in all directions except flexion. The mean DASH (Disabilities of the Arm, Shoulder and Hand) score14 was 19, and the average Mayo wrist score8 was 78. While the study demonstrated success in preserving wrist functionality, eight of the sixteen tested wrists developed osteoarthritis. Despite this 50% prevalence, patient satisfaction had not deteriorated at the time of the latest follow-up.
Luchetti et al. reported success with the Mayo dorsal intercarpal ligament capsulodesis technique in a study of fifteen patients with chronic stage-1 or 2 instability15. The injury grade was assessed with use of wrist arthroscopy prior to surgery; this evaluation allowed for correlation between the injury grade and the results on magnetic resonance imaging (MRI). The study showed a reduction in pain, as measured with a visual analog scale (VAS), from 8 preoperatively to 1 postoperatively. The authors also noted an increase in grip strength (from 26 to 33 kg) but a reduction of wrist flexion and extension (approximately 10%). The average DASH score improved from 59 preoperatively to 27 at the time of the latest follow-up.
Brunelli and Brunelli pioneered the use of a flexor carpi radialis tendon graft to reconstruct the scapholunate ligament, weaving the flexor carpi radialis tendon toward the dorsal surface through a hole in the distal aspect of the scaphoid and securing it over the scapholunate interval16. This technique allows one operation to simultaneously address the scaphotrapezial and scapholunate ligament deficiencies.
Sousa et al. evaluated the Brunelli tenodesis procedure in a retrospective review of twenty-two patients with posttraumatic stage-3 or 4 scapholunate instability who were followed for an average of sixty-one months17. The study revealed substantial loss of range of motion in multiple directions compared with the contralateral side. Wrist flexion and extension decreased by 23° and 22°, respectively, and radial and ulnar deviation decreased by 6° and 3°, respectively. The average VAS score for pain was 2 of 10. The average postoperative DASH score for function was 16; however, an outlier with osteonecrosis of the scaphoid and a score of 60 might have disproportionately inflated this result. Grip strength was found to be an average of 67% of that on the contralateral side. This tendon graft procedure proved to be most effective for patients without degenerative changes as tendon reconstruction further increases the risk of postoperative scapholunate dissociation. Twenty of the twenty-two patients successfully returned to work by the time of the latest follow-up. Complications included osteoarthritis (three patients), osteonecrosis (one), and complex regional pain syndrome (one).
Tri-Ligament Tenodesis (Modified Brunelli Tenodesis)
Garcia-Elias et al. described a modified tri-ligament tenodesis involving the scaphotrapezial ligament, the dorsal segment of the scapholunate ligament, and the dorsal segment of the radiotriquetral ligament1. This technique simultaneously strengthens the connection between the scaphoid bone and the distal carpal row, reconstructs the dorsal segment of the scapholunate ligament, and applies tension to the radiotriquetral ligament in order to pull the lunate and triquetrum to the radial aspect of the wrist. This procedure has shown particular utility for patients with stage-4 scapholunate instability, which involves irreparable scapholunate injury without cartilage degeneration.
Garcia-Elias et al. reviewed the results of this procedure in a study of thirty-eight patients with stage-3 to 5 symptomatic scapholunate dissociation1. At the time of the latest follow-up (average, forty-six months), twenty-eight of the thirty-eight patients reported complete pain relief. Ten patients reported persistent pain, with two patients experiencing pain with minimal wrist movement and eight patients reporting discomfort only during strenuous activity. The average range of motion at the time of follow-up was 51° of flexion (74% of the value on the contralateral side), 52° of extension (77%), 15° of radial deviation (78%), and 28° of ulnar deviation (92%). Grip strength remained at 65% relative to the contralateral side. Osteoarthritis was the most frequent complication; of the thirty-eight patients tested, seven developed degenerative osteoarthritis at the tip of the radial styloid and two developed global osteoarthritis.
Talwalkar et al. reported similar results after the tri-ligament tenodesis18. In a study of 162 patients with chronic stage-2 through 4 scapholunate instability, the mean loss of flexion-extension was 33° (26%), the mean loss of radioulnar deviation was 13° (12%), and the mean VAS pain score was 3.67. In addition, the authors reported an average 20% decrease in grip strength compared with the contralateral side.
The goal of the scapholunotriqeutral tenodesis technique is to reduce scaphoid subluxation and maintain the relationship between the scaphoid and the lunate by inserting a graft across the center of the scapholunate joint. The technique reroutes a portion of the flexor carpi radialis tendon through transosseous tunnels spanning the scaphoid, lunate, and triquetrum. Secondary stabilizers, including the dorsal intercarpal ligament, are then augmented by passing the tendon graft back to the scaphoid, crossing over the triquetrum and the proximal aspect of the capitate. Ultimately, this technique reinforces the translational relationship between the scaphoid and the triquetrum, augmenting the stability of the scapholunate articulation19.
Ross et al. conducted a prospective study on eleven patients with stage-1 through 4 instability who underwent scapholunotriquetral tenodesis, all of whom demonstrated good clinical and radiographic outcomes after an average duration of follow-up of fourteen months19. The average VAS score for pain with activity decreased from 18 to 14. The total arc of flexion-extension decreased slightly from 130° to 102°. In addition, the mean DASH score improved from 50 preoperatively to 21 postoperatively. The mean grip strength improved from 37 to 44 kg. Radiographically, the mean scapholunate interval decreased from 4.2 to 1.7 mm at the time of the latest follow-up and the mean scapholunate angle decreased from 80.5° to 56.8°. No patient in that study developed osteonecrosis of the scaphoid or lunate after surgery.
Dorsal Dynamic Tenodesis Using Extensor Carpi Radialis Brevis Tendon (Four-Bone Tendon Weave)
Almquist et al. described a four-bone ligamentous weave reconstructive technique involving the use of a strip of the extensor carpi radialis brevis tendon20. With that method, the tendon is first passed through the capitate from the dorsal aspect to the palmar aspect and then is passed in a reverse direction through the scaphoid. Next, it follows a similar pattern through the lunate and the radius. The extensor carpi radialis brevis tendon is then anchored to the distal aspect of the radius with drill-holes. Finally, either a suture or a cerclage wire is used to attach the scaphoid and lunate until healing is complete15,21.
Links et al. reported success with this four-bone tendon weave technique in a retrospective cohort study of twenty-three patients with chronic stage-1 through 5 scapholunate dissociation21. Range of motion was decreased in all planes; flexion, extension, and radial and ulnar deviation were restricted to 27°, 36°, 14°, and 21°, respectively, after surgery. In contrast, this procedure was shown to increase average grip strength from 30 to 34 kg (p < 0.001). The average VAS pain score improved from 6.7 preoperatively to 3.4 postoperatively, and the average DASH score improved from 67.5 to 45.1. The average scapholunate gap decreased from 3.7 mm preoperatively to 3.0 mm after surgery, and the average scapholunate angle decreased by 8°. Links et al. reported no complications in the cohort that received the four-bone tendon weave.
The original Brunelli technique inspired the development of the quad-ligament tenodesis technique. With this method, the flexor carpi radialis tendon graft is advanced through the scaphoid to secure four secondary stabilizers of the scaphoid: the volar segment of the scaphotrapezial ligament, the dorsal segment of the scapholunate ligament, the dorsal intercarpal ligament, and the dorsal radiocarpal ligament15,22.
Bain et al. reported good clinical outcomes for eight patients who underwent quad-ligament tenodesis22. Garcia-Elias staging was impossible as the radioscaphoid angle and osteoarthritis status were not discussed. Patients showed substantial improvement in terms of pain and reported overall satisfaction; the average VAS pain score improved from 5.8 preoperatively to 2.1 at the time of the latest follow-up. On the average, extension decreased to 56° (91% of the value for the contralateral wrist), flexion decreased to 44° (70%), and grip strength decreased to 41 kg (95%). Despite the acceptable preservation of kinematics, Bain et al. found less favorable radiographic parameters; postoperatively, the mean scapholunate gap measured 3.0 mm, and the mean scapholunate angle was 71°. No complications were reported in their study.
Scapholunate Reconstruction Using Autologous Free-Tissue Graft
An abundance of research involving bone-tissue-bone composite grafts has been targeted toward designing a scapholunate articulation capable of mimicking the dorsal segment of the SLIL23. To ensure biomechanical stability, any candidate replacement graft should exhibit strength and stiffness that are comparable with those of the scapholunate ligament. Autologous free-tissue grafts have shown promising results as the integration of a bone block into an osseous tunnel creates a solidly fixed end point23. In the following paragraph, we will describe a bone-extensor retinaculum-bone graft that has shown utility in scapholunate reconstruction procedures.
Bone-Extensor Retinaculum-Bone Graft from Distal Part of Radius
To our knowledge, Harvey and colleagues were the first to describe a bone-tissue-bone technique using a graft harvested near the Lister tubercle on the distal part of the radius; bone and graft were fitted into the dorsal aspects of the scaphoid and lunate with a retinaculum-periosteal soft-tissue sleeve arching between the two bones23. Weiss evaluated the efficacy of this technique in a study of fourteen patients with static, stage-1 through 5 scapholunate instability who were followed over a forty-three-month period24. Twelve of the fourteen patients reported an absence of pain both at rest and with strenuous activity of the wrist. The arc of motion decreased slightly in all planes; the postoperative values averaged 52° of extension, 76° of flexion, 9° of radial deviation, and 19° of ulnar deviation. Grip strength improved by 46% in patients without postoperative pain and 30% in the two patients with pain during strenuous activity. Radiographically, the scapholunate interval was reduced to 3 mm in thirteen patients; one patient demonstrated a gap of 4 mm without associated symptoms. The mean scapholunate angle was 50°. In terms of complications, Harvey et al. noted one case of skin breakdown over a prominent buried scapholunate fixation pin and five cases of neurapraxia of the sensory branch of the radial nerve, two of which resolved independently. Similarly, Soong et al. evaluated a bone-retinaculum-bone autograft in patients with stage-3 through 6 dynamic scapholunate instability and concluded that this reconstruction technique is a viable treatment option in cases in which the scaphoid and lunate can be reduced25.
Scapholunate Axis Method (SLAM)
This technique involves the use of a two-tailed tendon autograft that is placed along the axis of rotation of the scaphoid and lunate and is further secured with a tendon graft anchor. Coupled with reconstruction of the critical dorsal segment of the SLIL, the goal of the scapholunate axis method (SLAM) is to create a multiplanar tether between the two bones26.
In a cadaveric study comparing methods of scapholunate reconstruction, Lee et al. concluded that the SLAM reconstruction method exceeds the biomechanical characteristics of the Blatt capsulodesis and the three-ligament tenodesis in terms of adjusting the scapholunate angle and preserving range of motion26. Using twelve cadaver wrists that were randomized to one of the three procedures, they found that the SLAM procedure corrected the scapholunate angle by 20°, whereas the Blatt capsulodesis and three-ligament tenodesis corrected it by 6° and 13°, respectively. The SLAM procedure resulted in improvement of the scapholunate interval, with a mean difference of −0.02 mm, compared with 6 mm for the Blatt capsulodesis and 1 mm for the three-ligament tenodesis. These results suggest that promising outcomes can be expected if this procedure is used as a treatment option in a future clinical series.
Conclusions and Clinical Care Recommendations
In reviewing the myriad reconstruction techniques described in the current literature, we have stratified scapholunate reconstruction procedures according to our opinion of their efficacy in treating discrete stages of instability, chronicity, and arthrosis. We have set forth our preferred treatment algorithm in Table II.
While no current procedure can completely restore the kinematics of the wrist joint, select methods have proven to be highly effective for addressing particular symptoms of scapholunate instability. According to the Garcia-Elias algorithm, patients with stage-1 instability have considerable improvement when managed with capsulodesis with percutaneous Kirschner wire fixation and subsequent proprioception reeducation of the flexor carpi radialis to ensure scaphoid stability. As stage-1 instability is associated with only a partial separation, no reconstruction of the dorsal segment of the ligament is necessary. In contrast, stage-2 instability is an indication for the use of transosseous or anchoring sutures to reverse the dorsal ligament avulsion. We have also concluded from our grouped comparison that patients with Garcia-Elias stage-1 instability benefit most from capsulodesis as the midcarpal joint is well preserved.
Our review indicates that in patients with either stage-3 or stage-4 instability, bone-ligament-bone grafts and tendon reconstruction techniques, respectively, have shown the most positive postoperative outcomes. Bone-ligament-bone grafts are particularly effective for allowing rapid postoperative healing as the procedure requires the fewest additional incisions.
For patients with stage-5 instability, Garcia-Elias et al. stated that the high likelihood of scapholunate ligament failure after reconstruction is reason enough to perform a partial arthrodesis procedure despite its associated morbidities1. Effective partial arthrodesis procedures include the scaphotrapeziotrapezoidal arthrodesis or scaphocapitate arthrodesis to keep the scaphoid and radius in alignment27. Finally, stage-6 instability is an indication for a procedure that will preserve carpal motion, such as a scaphoidectomy with midcarpal arthrodesis or a proximal row carpectomy.
In addition to identifying which techniques address specific symptoms, our review has allowed us to determine which techniques are less efficacious. For example, the soft-tissue reconstruction techniques discussed in the present article do not adequately treat instability in patients with degenerative changes or those in whom reduction of the scapholunate joint is impossible. In addition, the scapholunate advanced collapse method has proven ineffective when damage to both the scapholunate and lunotriquetral ligaments has been identified.
Numerous reports have addressed the specific outcomes of scapholunate reconstruction procedures. While several investigators have stratified treatments on the basis of preoperative symptoms, the current literature lacks a broad summary of techniques. Our review provides a comprehensive analysis of scapholunate reconstruction methods, synthesizing established classification schemes with new data in order to cover the spectrum of scapholunate instability treatment. As evidenced by our review, scapholunate ligament injury is a multifactorial problem, with each case requiring individualized treatment. The scapholunate reconstruction techniques discussed above have shown promising improvements in terms of wrist strength, range of motion, and overall patient satisfaction, but no existing treatment has consistently produced outcomes that completely restore preinjury wrist functionality.
Source of Funding: No external funds were received in support of this work.
Investigation performed at Beth Israel Deaconess Medical Center, Boston, Massachusetts
Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.
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