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Acute Scapholunate Ligament Injuries: Current Concepts
Acute Scapholunate Ligament Injuries: Current Concepts Ali Izadpanah, MD,* and Sanjeev Kakar, MD† Scapholunate ligamentous injuries are the most common interosseous carpal injuries within young active individuals, with an incidence up to 54% after distal radius fractures. If left untreated, they can lead to scapholunate ligament advanced collapse. Controversy exists in the management of acute scapholunate ligament injuries. In this article, we review the current concepts in diagnosis, classification, and surgical management of these injuries. Oper Tech Sports Med ]:]]]-]]] C 2016 Elsevier Inc. All rights reserved.
KEYWORDS Scapholunate ligament, Acute injury, Wrist instability, Carpal instability, Wrist sprain
Types of Carpal Instability
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arpal instability can be classified into 4 major patterns: carpal instability dissociative (CID), carpal instability nondissociative (CIND), carpal instability complex, and carpal instability adaptive.1 CID occurs when there is injury between the bones of the same carpal row by fracture or ligamentous disruption, such as a scapholunate ligament (SL) injury, in contrast to CIND, which occurs when there is dysfunction between 2 rows such as between the distal radius and proximal carpal row or between carpal rows.2 When CID and CIND coexist, it is classified as carpal instability complex; an example of which would be a perilunate dislocation.3 Finally, if the origin of carpal instability lies outside of the carpus (proximal or distal), the pattern of instability is known as carpal instability adaptive, for example, instability secondary to a distal radius malunion.4 Tears in the scapholunate interosseous ligament (SLIL) are the most commonly encountered intercarpal ligament injury with an incidence of up to 20% in “sprained” wrists and as high as 21.5%-54% after displaced distal radius fractures. This could lead to a proximal CID collapse pattern. Following the tear, the scaphoid has a tendency to flex around the palmar radioscaphoidcapitate ligament secondary to palmar torque from the scaphotrapezio-trapezoid (STT) articulation. Conversely, the lunate has a tendency to extend secondary to the
*Department of Surgery, University of Montreal, Montréal, Québec, Canada. †Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN. Address reprint requests to Sanjeev Kakar, MD, Department of Orthopedic Surgery, Mayo Clinic, 200 First St SW, Rochester, MN 55905. E-mail: [email protected]
http://dx.doi.org/10.1053/j.otsm.2016.02.002 1060-1872//& 2016 Elsevier Inc. All rights reserved.
extension moment transmitted by the triquetrum via the lunotriquetral ligament. As the secondary stabilizers of the scapholunate joint become attenuated, that is, the volar radioscaphocapitate (RSC) ligament, the short radiolunate and long radiolunate (LRL) ligaments, the dorsal intercarpal (DIC), the STT, and the dorsal radiotriquetral ligaments, dorsal intercalated segment instability (DISI) deformity ensues.5 Scapholunate instabilities can also be classified as predynamic, dynamic, or static. If the injury causes only partial SLIL tear, it would appear as predynamic instability with normal radiographs, (including stress views) but may have some magnetic resonance imaging (MRI) and arthroscopic evidence of SLIL tear. On the contrary, as the tear progresses, a dynamic (seen on stress views) and eventual static instability (visible on standard unstressed radiographs) can ensue.1 Despite being the most common interosseous ligamentous wrist injury, the natural history of SL tears is not clearly understood. Many of these injuries go undetected. Watson studied 4000 wrist radiographs and identified 210 cases of wrist arthritis. The evolution of arthritis in the scapholunate advanced collapse (SLAC) pattern was then proposed by his findings.6 Arthritis starts at the radial styloid and progresses to include the radioscaphoid articular surface. As the SL interval widens, the head of the capitate migrates proximally into the widened interval, resulting in arthritic changes at the lunocapitate joint6 (Fig. 1). O’Meeghan et al7 evaluated 11 patients with arthroscopicproven SLIL injuries without any radiographic evidence of SL gapping or secondary osteoarthritis, and noted that in the absence of complete dissociation of the scapholunate, there would not be an eventual widening of the SL interval or DISI deformity within a 7-year follow-up period. Only 1 out of the 1
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A. Izadpanah, S. Kakar Selective sectioning studies by Werner et al13 have established that the SLIL is the primary stabilizer of this complex, and the secondary stabilizers are responsible for stabilizing the SL at the extremes of motion. In a cadaveric model, increasing rotatory subluxation of the scaphoid led to a progressive decrease of the articular contact surface area (201 scaphoid subluxation caused a 77% reduction in the articular contact).14 The most common mechanism of SL injury as originally described by Mayfield et al15 is a fall on an extended, ulnarly deviated, and supinated wrist. Given the relative strength of the dorsal SL ligament, these tears tend to start palmar and propagate dorsal. This is the basis for progressive SL instability from predynamic to eventual static deformity with a fixed flexed scaphoid and an extended lunate.
History and Physical Examination Figure 1 Scapholunate advanced collapse (SLAC) wrist arthritis. There is evidence of scapholunate diastasis with radioscaphoid and midcarpal arthritis, and proximal migration of the capitate.
11 patients developed radiographic arthritis, but all patients developed chronic wrist pain affecting their activities of daily living.7
Relevant Anatomy and Biomechanics of Injury The SLIL is a true intra-articular ligament bathed in synovial fluid with poor intrinsic healing potential.8 It comprises a dorsal, membranous, and a palmar segment. The dorsal segment is the strongest of the 3 with a yield strength of 260 N and fibers that are transverse and parallel. The fibers of the palmar segment are obliquely oriented with a yield strength of 120 N. The membranous portion has a yield strength of 65 N and is largely made of anisotropic fibrocartilage, blending in with the articular cartilages of the scaphoid and lunate.9,10 (Fig. 2). The SL ligament is highly innervated with proprioceptive receptors including Pacini (perceiving acceleration and deceleration) and Ruffini (perceiving joint positioning) receptors that contribute to dynamic joint positioning.11 The palmar subregion of SLIL contains the greatest amount of neural structures and mechanoreceptors compared to the dorsal subregion, which is predominantly comprised of densely packed collagen fibers with limited innervation.11 The motion of the carpus is complex. The proximal row acts as the intercalated segment within the wrist and is devoid of any musculotendinous insertions. Its movement is determined by the complex interactions of the forearm and the distal carpal row. Many of the adjacent carpal ligaments act as critical components in SL stability, in particular, the STT and the RSC ligaments.12
Patients may complain of weakness and dorsal radial wrist pain during loading of the extended wrist after a wrist injury. Associated pain may limit their range of motion (ROM) and grip strength affecting different activities of daily living, that is, lifting heavy objects, grocery shopping, or using a screwdriver. Given this, many patients may have to adapt to their lifestyles.7 On examination, in an acute injury, there may be swelling, ecchymosis, and pain over the dorsoradial aspect of the wrist. This area can be found just distal to Lister tubercle with the wrist in a partially flexed position. A positive Watson scaphoid shift test (pain over the dorsal scaphoid with radial deviation of the wrist and a dorsally directed force on the scaphoid tuberosity) could indicate a complete or near-complete disruption of the dorsal portion of SLIL. The palpable click during this maneuver test is secondary to the scaphoid shifting in relation to the remaining carpal bones. Frequently, a clunk can be felt when releasing the force as the scaphoid relocates from the dorsal rim of distal radius into the radioscaphoid fossa. This should be compared with the contralateral side. A unilateral Watson shift test is associated with an increased risk of SLIL injury, with positive and negative likelihood ratios of 2.9 and 0.28, respectively.16,17
Imaging, Diagnosis, and Classifications After a detailed history and examination, initial investigation should commence with posteroanterior and lateral plain wrist radiographs. This should be examined for any carpal fracture and increased SL diastasis and angle. Plain radiographs are often normal with dynamic instability. Given this, stress views are advocated as they may demonstrate abnormal widening of this interval. In a cadaveric study by Lee et al investigating different stress views (the “clenched pencil” view, clenched fist views in varying positions, and traction views) (Fig. 3), the “clenched pencil” view was considered the best stress view to demonstrate dynamic SL instability18 (Fig. 4). It is important to obtain radiographs of the contralateral wrist, as bilateral SL
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Figure 2 Image demonstrating the scapholunate ligament and its attachments to the scaphoid and lunate. (Adapted with permission from Berger et al.10) Copyright 2011 American Society for Surgery of the Hand.11 (Adapted with permission from Elsevier).
diastasis can be a normal variant.19,20 Although patients with widened SL interval on plain radiographs are considered to have static instability (implying damage to both SLIL and secondary stabilizers), up to 50% of normal wrists can have an SL interval distance of 44 mm.20 Having the SL interval width set at 2.5 mm, the sensitivity for detecting a true SLIL lesion is only 60%, the specificity is 75%, and the positive likelihood ratio is 2.41.21 Given this, it is important to
A
weigh the radiographic findings with a clinical suspicion of SL injury. To aid in its diagnosis, advanced imaging may be required. Weiss et al22 investigated the role of wrist arthrography and demonstrated up to 74% incidence of bilateral articular communications between midcarpal and radiocarpal joint spaces despite unilateral symptoms (false negative); only 10% of arthrograms showed communications correlating with
B
Figure 3 Image demonstrating the unstressed (A) and stressed “clenched fist” (B) views with SL interval widening; arrows are pointing to the SL interval.
A. Izadpanah, S. Kakar
4 pain localization (true positive). However, using concomitant fluoroscopy and arthrography can increase the sensitivity of the study up to 60% and the specificity to almost 100%. This would translate into an accuracy of 84% when compared with wrist arthroscopy as the gold standard.22 With static SL injuries, normal alignment of the carpus would be disrupted. The normal scapholunate angle (301-601) increases to greater than 601 secondary to scaphoid flexion and lunate extension. Additionally, the lunocapitate angle increases to greater than 101 with dorsal translation of capitate. On posteroanterior wrist x-rays, scaphoid flexion could also lead to the “scaphoid ring sign” secondary to the flexion of the scaphoid causing the overlap of the distal and proximal poles to appear as a ring. High-resolution (3.0 T) MRIs have demonstrated a sensitivity range of 70%-81% and specificity near 100% with a positive predictive value of 97%-100% in diagnosing SL injuries.23 Magnetic resonance arthrograms compared to plain MRIs have been demonstrated to be more sensitive to SL tears24-26 (Fig. 5). Wrist arthroscopy is considered to be the gold standard for diagnosis, especially in early predynamic and dynamic stages where other imaging studies may be inconclusive. Geissler et al27 in 1996 advocated for the use of both radiocarpal and midcarpal portals during wrist arthroscopy to increase the sensitivity to diagnose SL injuries (Table 1) (Fig. 6). Although many studies have demonstrated good correlation between Geissler grading and the degree of ligamentous tear, there are some limitations to its use.28,29 The original grading system was derived from patients with displaced intra-articular distal radius fractures. It has not yet been validated in patients without a traumatic wrist injury to identify its intraobserver and interobserver reliabilities.30 Rimington et al conducted a study in 83 fresh-frozen cadavers devoid of any previous wrist trauma to assess the validity of Geissler classification. It was noted that the study showed the poor correlation between the grades of laxity in the SLIL ligament, the SL interval, and the angle. Given these findings, the authors
Figure 5 Axial MRI showing volar SL tear. (Color version of figure is available online.)
concluded that this classification may help in describing intercarpal ligamentous laxity rather than diagnosing pathologic instabilities.31 Lee et al28 conducted a cadaveric study correlating the degree of Geissler grading to SL diastasis. It was noted that Geissler grade II was associated with SL sectioning only. Geissler grade III developed after division of the dorsal SLIL and continued sectioning of the volar extrinsic ligaments. Geissler grade IV diastasis occurred after sectioning of both SLIL and all of the dorsal extrinsic ligaments.28. These findings may be of use when determining the type of surgical reconstructions for this injury. In a similar attempt to correlate the arthroscopic findings with the degree of ligament injury, Messina et al described the European Wrist Arthroscopy Society classification. This is an anatomical-pathological classification based on sectioning of different portions of SLIL (Table 2). The authors identified different stages of SL injury that would contribute to scapholunate dissociation (SLD).29 Cadaveric dissections demonstrated that the SL gap increased after additional sectioning of at least 2 secondary stabilizers (RSC or LRL volarly and DIC dorsally). The diastasis increased significantly with sectioning of other extrinsic ligaments.29,31
Treatment
Figure 4 Image demonstrating the “clenched pencil” view adapted with permission from Lee et al.28 Copyright 2011 American Society for Surgery of the Hand (Adapted with permission from Elsevier). (Color version of figure is available online.)
A practical algorithm to help guide the surgical treatment of SL injuries was devised by Garcia-Elias et al32 (Table 3). It comprises several factors that collectively need to be considered to guide the optimal treatment. The first is the integrity of the dorsal SLIL. Partial SLIL tears tend to involve the palmar and membranous portion with the dorsal component remaining intact. In the context of an intact dorsal ligament, the scaphoid shift test may be negative, the arthrogram inconclusive, but a high-resolution MRI or magnetic resonance arthrograms or wrist arthroscopy might be able to identify the potential volar or membranous segments tears. Next is the healing potential of the ligament; acute avulsion type injuries have a greater propensity to heal when compared with chronic mid substance ruptures that are less likely to heal without surgical intervention.33 Third is the status of the secondary stabilizers12,34; dorsal and volar STTs, DIC,
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Table 1 Geisslers Arthroscopic Grading of Scapholunate Interosseous Ligamentous Injuries Grade Description I II III IV
Attenuation/hemorrhage of interosseous ligament as seen from the radiocarpal joint. No incongruency of carpal alignment in the midcarpal space. Attenuation/hemorrhage of interosseous ligament seen through radiocarpal portals. Step-off seen from midcarpal portals. A slight gap (less than width of a probe) between carpals may be present. Step-off of carpal alignment is seen through both radiocarpal and midcarpal portals. The probe may be passed through the gap between carpals. Step-off of carpal alignment seen in both the radiocarpal and midcarpal portals. Gross instability with manipulation is seen and a 2.7 mm arthroscope may be passed through the gap between carpals (drive-through sign).
dorsal radiotriquetral, short radiolunate, LRL, and scaphocapitate ligaments. These help to maintain the scaphoid’s alignment preventing the rotatory subluxation of the scaphoid after a complete SL disruption. Fourth is whether the carpus is malaligned and whether it can be reduced into its anatomical position. This is an important factor influencing the decision for soft tissue reconstructions. With chronic injuries, fibrosis can develop and prevent reduction of the scapholunate joint. The location of this fibrosis tends to be at the palmar and proximal edge of lunate and the medial corner of the scaphoid tuberosity.35 If the carpus cannot be easily reduced, soft tissue reconstructions may fail.32 The last component that needs to be considered is the state of the articular cartilage of the carpus.6 If there is evidence of degenerative changes, SLIL reconstructions are contraindicated, and one should proceed to more salvage-type procedures such as a scaphoid excision and 4-bone fusion.32
Nonoperative Management Treatment Numerous muscles have been shown to affect SL kinematics including the flexor carpi radialis (FCR), flexor carpi ulnaris, extensor carpi radialis brevis (ECRB), extensor carpi radialis longus, and abductor pollicis longus. Garcia-Elias suggests that in the presence of predynamic or dynamic instabilities, the FCR and ECRB may be able to stabilize the SLIL through
strengthening and proprioceptive training. The ECRB acts to stabilize the lunate by promoting extension and placing volardirected pressure on the capitate counteracting the extension of the lunate. The FCR, in return, generates a dorsal and supination vector that resists the scaphoid from rotating into flexion and pronation.36 It is worth noting, however, that in a complete SLIL tear, the forces exerted by FCR could potentially induce a dorsal translatory force leading to further subluxation of the proximal pole of scaphoid. The role of conservative management in treatment of SLIL injuries is controversial. O’Meeghan proposed nonsurgical management for grade I (minor) SL ligament injuries. However, it should be noted that all patients in the report had some level of pain, decreased grip strength, and ROM with difficulties for activities such as grocery shopping and other activities of daily living; many had to change lifestyle and work.2 In our practice, for acute predynamic injuries, we attempt a period of wrist immobilization followed by FCR and ECRB strengthening.
Operative Management There have been a number of surgical techniques described for the treatment of SL injury. They are limited to case reports and retrospective series with limited power and validity to advocate one treatment over the next. What follows is a review of some of the more popular surgical techniques and their outcomes.
Surgical Techniques Reduction and Ligamentous Repair Acutely diagnosed SL injuries may fall into Garcia-Elias stage 1 or 2 SLD. The ligament is usually avulsed off of the scaphoid and may be reparable. Different techniques for primary repair of SLIL tears have been proposed, ranging Table 3 Staging of Scapholunate Dissociations (SLD) Devised by Garcia-Elias33 Stage Figure 6 Midcarpal view of the scapholunate interval showing Geissler grade 3 volar diastasis. Scaphoid is on the right and lunate on the left. Probe passing through the scapholunate interval with no evidence of degenerative changes in the distal scaphoid or lunate. (Color version of figure is available online.)
Intact SLIL Reparable SLIL Normal alignment Reducible Normal articular
1
2
3
4
5
6
Yes Yes Yes Yes Yes
No Yes Yes Yes Yes
No No Yes Yes Yes
No No No Yes Yes
No No No No Yes
No No No No No
A. Izadpanah, S. Kakar
6 Table 2 Arthroscopic EWAS Classification and the Corresponding AnatomoPathological Findings EWAS Arthroscopic Stage I. II. (lesion of membranous SLIL) III A. (partial lesion involving volar SLIL) III B. (partial lesion involving dorsal SLIL) III C. (Complete SLIL tear and joint is reducible) IV. (Complete SLIL tear with SL gap) V.
SLIL Test From Midcarpal Joint No passage of probe Passage of probe tip without widening (stable) Volar widening on dynamic testing
AP Radiographs Findings Not found Lesion of proximal/membranous SLIL
Lesion of anterior and proximal SLIL with/without lesion of RSC-LRL Dorsal widening on dynamic testing Lesion of dorsal and proximal SLIL with partial dorsal intercarpal ligament tear Complete widening on dynamic testing; Complete lesion of SLIL with 1 extrinsic ligament (DIC or Reducible on probe removal RSC/LRL) SL gap with passage of probe from Complete lesion of SLIL and extrinsic ligaments (DIC midcarpal to radiocarpal and RSC/LRL) Wide SL with passage and DISI deformity Complete lesion of SLIL and extrinsic plus one or more other ligaments (TH, ST, and DRC)
AP, anteroposterior; DIC, dorsal intercarpal ligament; DRC, dorsoradiocarpal; RC, radiocarpal; ST, scaphotrapezial; TH, triquetrohamate.
from arthroscopically assisted reduction and pinning to open dorsal approach and stabilization using suture anchors or transosseous sutures with comparable results.37 Whipple38 described the role of arthroscopy in the reduction and transcutaneous pin stabilization of acute SL injuries.39 Whipple reviewed the results of arthroscopic management of scapholunate instability after a follow-up duration of 1-3 years. Patients were divided into 2 groups depending on the time since injury and SL diastasis. It was noted that 83% of patients had good results if their treatment was within 3 months of injury with a SL gap of less than 3 mm. In
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contrast, only 53% of patients undergoing arthroscopic reduction and pinning after 3 months with more than 3 mm SL interval had symptomatic relief. Wahegaonkar and Mathoulin reported on repair of SL injuries with an arthroscopic-assisted dorsal capsulodesis. A total of 57 consecutive patients with Garcia-Elias stages 24 SL injury were treated with a mean time to injury of 10 months and follow-up of 31 months. The mean postoperative grip strength of the operated side was 93.4% when compared with the unaffected side. The DISI was corrected in all cases on postoperative radiographs, and the mean difference between
C
B
E
F
Figure 7 Arthroscopic-assisted volar capsuloligamentous repair. (Adapted with permission from del Pinal.41 Copyright thieme (Permission requested). (Color version of figure is available online.)
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Capsulodesis
Figure 8 Berger’s capsulodesis. Image adapted with permission from Michelotti BF, et al: Chronic scapholunate ligament injury: Technique in repair and reconstruction. Hand Clin 31(3):437-449, 2015; Copyright 2015 Elsevier Inc. (Adapted with permission from Elsevier).
the postoperativeand preoperative SL angles was 8.951. The Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) scores had improved to 8.3 from 46. The average grip strengths had increased by 14 kg from 24 kg preoperatively and with an improvement in preoperative pain scores.40 Del Pinal41 reported on the role of all-inside arthroscopic suturing technique for the repair of volar SL or the plication of space of Poirier (Fig. 7). Using the midcarpal portals, a 22gauge needle is inserted from volar to dorsal immediately ulnar to the FCR, 1 cm proximal to the distal wrist crease. After appropriate positioning, a Tuohy needle is inserted through the same pathway and a 2-0 polydioxanone suture is threaded through and pulled through the radial midcarpal portal. The needle is then retracted from the capsule, while remaining subcutaneously, and slid just distal to the palmar edge of the scaphoid. The suture is then again inserted and grasped via the radial midcarpal portal and using a sliding knot, is secured to close the palmar diastasis by imbricating the SL and LRL ligament.41 The use of thermal shrinkage for the management of ligamentous injuries has been shown to have some promise. Darlis et al in 2004 described the use of arthroscopic debridement and thermal shrinkage for the treatment of partial SLIL tears. In total, 14 patients with tears involving the volar and membranous segments of the SL ligament were treated. Further, 8 patients had excellent relief (complete relief of symptoms), 6 good, 1 fair, and 1 poor.42 Hirsh et al evaluated the outcome of patients with Geissler grade II who underwent electrothermal shrinkage; 2 patients had presented within 6 weeks of injury, whereas the remainder presented after 6 weeks following the injury. At final follow-up at 28 months, 9 patients (90%) were asymptomatic with return to normal preoperative activities.43
Capsulodesis is a procedure designed to use a portion of the dorsal capsule to control the position of the carpus. It can be used as an augmentation after primary ligamentous repair or the definitive reconstructive procedure. Blatt44 described a procedure that involved a proximally based strip of dorsal capsule tethered onto the dorsal scaphoid to prevent scaphoid flexion. The scaphoid is temporarily pinned to the capitate with Kirschner wires for 12 weeks before it is removed and ROM exercises started. Blatt reported on the outcome of this technique in 12 patients with “gratifying” results. Full recovery of wrist extension and less than 201 of wrist flexion loss with an average recovery of 80% of grip strength was achieved in this group.44 Berger et al45 later described a modification of capsulodesis technique using a distally based strip of the DIC ligament tethered to the dorsal lunate. The DIC is detached from the triquetrum and sutured to the dorsal-proximal corner of the lunate after reduction of the scaphoid (Fig. 8). Moran et al in 2005 reported on the intermediate-term outcome of dorsal capsulodesis techniques using both Blatt’s (11 patients) and Berger’s (20 patients) modifications for chronic SL dissociations. A total of 18 patients had dynamic instability, 13 had static deformity, and time from injury to surgery averaged 20 months. There was a 20% decrease in wrist range of motion, no change in grip strength with 58% of patients having mild to no pain, 21% had moderate pain, and 21% continued to complain of pain with activities. Further, 4 patients had to permanently change employment and 2 underwent salvage procedures. Time to surgery had no effect upon outcome, and at a final follow-up of 54 months, the average SL interval increased from 2.7 mm preoperatively to 3.9 mm postsurgery and the SL angle averaged 621.46 A modification of the DIC capsulodesis was proposed by Szabo47 who transposed the ligament from the trapezium and trapezoid and transferred it to the distal pole of scaphoid. A total of 15 patients were followed up for over 5 years. At final followup, patients had an average DASH score of 19 and 78 on the SF-12.48 The average SL angle was 621 and SL gap of 3.5 mm. Also, 58% of patients maintained a high degree of functionality, with half of all patients developing radiographic arthritis. Similar reports have shown high rates of satisfaction and symptomatic improvement in up to 80% of patients without a significant improvement in the SL interval or angle.49-51
Reduction and Association of Scaphoid and Lunate The reduction and association of scaphoid and lunate (RASL) procedure is designed to create a pseudoarthrosis between the scaphoid and lunate.52 The articular surfaces between the scaphoid and lunate are debrided and after the joint is reduced, a cannulated smooth compression screw is placed between them. The screw is either left in situ or removed after several months of healing.52 Koehler et al53 reported on an arthroscopic-assisted RASL procedure in 18 patients with chronic SL instability. After an
A. Izadpanah, S. Kakar
8 average follow-up of 3 years, the mean visual analog pain score was 2.5, DASH score of 8, and the grip strength averaged 84% of the uninjured wrist. A total of 4 patients underwent revision surgery. The authors noted that patients who had an SL gap of 5 mm and stage 1 SLAC wrist arthritis were poor candidates for this procedure. Caloia et al54 reported the outcome of 9 wrists undergoing arthroscopic RASL and found the grip strength to be improved at the final follow-up to 78% of the contralateral side and the arc of motion to be 1071. The average postoperative wrist ROM was 1071, 20% less than the preoperative ROM. The SL angle decreased from 70.51-59.31, and in 3 cases, the screws were removed owing to the loosening or symptomatic complaints. The visual analog pain score was improved from 5.4 preoperatively to 1.5 at last follow-up to 1.5 from a rated value of 5.4 preoperatively. Stern and Larson reported on the outcome of 8 wrists after RASL at 38 months follow-up using 3.0 mm headless cannulated compression screws. In all, 5 wrists had dynamic SL instability and 2 had static instability with an average time of 5 months (range: 1-17 months) from injury for all patients, with the exception of 1 patient who was injured several years ago. All patients were immobilized for 6 weeks in a thumb spica cast after surgery with strengthening exercises starting at 10-12 weeks.55 Authors reported that the SL interval decreased from 2.9 mm preoperatively to 2.2 mm immediately after surgery. At final follow-up, the SL interval was found to be 4.5 mm. Radiographic success (defined by maintenance of corrected SL diastasis, absence of DISI, and no progression of SLAC) was achieved in 3 of the 8 wrists. A patient developed radioscaphoid arthritis. The DASH and patient-rated wrist evaluation outcome questionnaires completed at final followup demonstrated an average DASH of 15 and patient-rated wrist evaluation score of 26. The grip strength averaged at 77% of the contralateral side, and the total active wrist arc of motion for flexion-extension at final follow-up had measured 991 when compared with 1081 preoperatively. Given these poor results, the authors advocated caution with this procedure.55
Ligament Reconstruction Techniques Three-Ligament Tenodesis In 1995, Brunelli and Brunelli35 proposed a technique during which the FCR tendon was used to stabilize the SL interval. During this procedure, a longitudinal slip of FCR (third in cross section) was harvested and tunneled volar to dorsal from the distal pole parallel to the distal articulation of scaphoid and then tightened to correct the scaphoid flexion by tethering the FCR to distal radius. Van Den Abbeele et al56 reported on a modification of this technique in 22 patients. In this technique, the FCR tendon, having been passed from volar to dorsal through the scaphoid, is looped under or though the dorsal radiolunotriquetral ligament and secured to the lunate. By not crossing the radiocarpal joint, the theory was that the wrist ROM would be preserved. The authors reported overall promising results in 17 of 22 patients with relief of pain and restoration of grip strength. Postoperative ROM was reduced in extension and flexion, remained unchanged for radial
deviation, and improved for ulnar deviation. The radiological appearance of dynamic or static scapholunate instability did not change after the procedure.56 Garcia-Elias reported results of 3 ligament tenodesis reconstruction at an average of 46 months follow-up in 38 patients with SLD. In total, 21 wrists showed Garcia-Elias stage 3, 8 had stage 4, and 9 had stage 5. A total of 29 patients in his series had returned to their normal activities, 7 had to downgrade their usual daily activities, and 2 had retired at the end of follow-up. The average ROM at final follow-up was 511 for flexion, 521 for extension, 151 for radial, and 281 of ulnar deviation. The average grip strength at final follow-up was only 65% of the contralateral without any evidence for scaphoid necrosis because of the bone tunneling. In total, 9 patients progressed to early stages of SLAC at final follow-up.32 The authors recommended this procedure for those who have reducible SL deformity comprising stages 3-4 SL instability.
Summary Scapholunate injuries are the most common interosseous carpal injuries that if left untreated, can lead to SLAC. Management of scapholunate dissociations despite being the most common carpal malalignment remains controversial. Conservative management may be considered in early stages of acute SLIL tears with wrist arthroscopy and surgical repair or reconstruction reserved for acute dynamic and static instabilities.
Reference 1. Linscheid RL, et al: Instability patterns of the wrist. J Hand Surg Am 8(5 Pt 2):682-686, 1983 2. Wright TW, et al: Carpal instability non-dissociative. J Hand Surg Br 19 (6):763-773, 1994 3. Siegert JJ, Frassica FJ, Amadio PC: Treatment of chronic perilunate dislocations. J Hand Surg Am 13(2):206-212, 1988 4. Allieu Y: Carpal instability—Ligamentous instabilities and intracarpal malalignments—Explication of the concept of carpal instability. Ann Chir Main 3(4):317-321, 1984. [366-7] 5. Gelberman RH, Cooney WP, Szabo RM: Carpal instability. J Bone Joint Surg Am 82a(4), 2000 6. Watson HK, Ballet FL: The SLAC wrist: Scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg Am 9(3):358-365, 1984 7. O’Meeghan CJ, et al: The natural history of an untreated isolated scapholunate interosseus ligament injury. J Hand Surg Br 28 (4):307-310, 2003 8. Sokolow C, Saffar P: Anatomy and histology of the scapholunate ligament. Hand Clin 17(1):77-81, 2001 9. Berger RA, et al: Constraint and material properties of the subregions of the scapholunate interosseous ligament. J Hand Surg Am 24(5):953-962, 1999 10. Berger RA: The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg Am 21(2):170-178, 1996 11. Mataliotakis G, et al: Sensory innervation of the subregions of the scapholunate interosseous ligament in relation to their structural composition. J Hand Surg Am 34(8):1413-1421, 2009 12. Short WH, et al: Biomechanical evaluation of ligamentous stabilizers of the scaphoid and lunate. J Hand Surg Am 27(6):991-1002, 2002 13. Werner FW, Short WH, Green JK: Changes in patterns of scaphoid and lunate motion during functional arcs of wrist motion induced by ligament division. J Hand Surg Am 30(6):1156-1160, 2005
Acute Scapholunate Injuries 14. Pappou IP, Basel J, Deal DN: Scapholunate ligament injuries: A review of current concepts. Hand 8(2):146-156, 2013 15. Mayfield JK, Johnson RP, Kilcoyne RK: Carpal dislocations: Pathomechanics and progressive perilunar instability. J Hand Surg Am 5 (3):226-241, 1980 16. LaStayo P, Howell J: Clinical provocative tests used in evaluating wrist pain: A descriptive study. J Hand Ther 8(1):10-17, 1995 17. Prosser R, et al: Provocative wrist tests and MRI are of limited diagnostic value for suspected wrist ligament injuries: A cross-sectional study. J Physiother 57(4):247-253, 2011 18. Lee SK, et al: Comparison of radiographic stress views for scapholunate dynamic instability in a cadaver model. J Hand Surg Am 36a (7):1149-1157, 2011 19. Cautilli GP, Wehbe MA: Scapho-lunate distance and cortical ring sign. J Hand Surg Am 16(3):501-503, 1991 20. Picha BM, Konstantakos EK, Gordon DA: Incidence of bilateral scapholunate dissociation in symptomatic and asymptomatic wrists. J Hand Surg Am 37(6):1130-1135, 2012 21. Megerle K, et al: The significance of conventional radiographic parameters in the diagnosis of scapholunate ligament lesions. Eur Radiol 21 (1):176-181, 2011 22. Weiss AP, Akelman E, Lambiase R: Comparison of the findings of tripleinjection cinearthrography of the wrist with those of arthroscopy. J Bone Joint Surg Am 78(3):348-356, 1996 23. Spaans AJ, et al: The value of 3.0-tesla MRI in diagnosing scapholunate ligament injury. J Wrist Surg 2(1):69-72, 2013 24. Moser T, et al: Wrist ligament tears: Evaluation of MRI and combined MDCT and MR arthrography. Am J Roentgenol 188(5):1278-1286, 2007 25. Scheck RJ, et al: The scapholunate interosseous ligament in MR arthrography of the wrist: Correlation with non-enhanced MRI and wrist arthroscopy. Skelet Radiol 26(5):263-271, 1997 26. Wang ML, Bednar JM: Lunatocapitate and triquetrohamate arthrodeses for degenerative arthritis of the wrist. J Hand Surg Am 37(6):1136-1141, 2012 27. Geissler WB, et al: Intracarpal soft-tissue lesions associated with an intraarticular fracture of the distal end of the radius. J Bone Joint Surg Am 78 (3):357-365, 1996 28. Lee SK, et al: Association of lesions of the scapholunate interval with arthroscopic grading of scapholunate instability via the geissler classification. J Hand Surg Am 40(6):1083-1087, 2015 29. Messina JC, et al: The EWAS classification of scapholunate tears: An anatomical arthroscopic study. J Wrist Surg 2(2):105-109, 2013 30. Rimington TR, et al: Intercarpal ligamentous laxity in cadaveric wrists. J Bone Joint Surg Br 92(11):1600-1605, 2010 31. Viegas SF, et al: The dorsal ligaments of the wrist: Anatomy, mechanical properties, and function. J Hand Surg Am 24(3):456-468, 1999 32. Garcia-Elias M, Lluch AL, Stanley JK: Three-ligament tenodesis for the treatment of scapholunate dissociation: Indications and surgical technique. J Hand Surg Am 31(1):125-134, 2006 33. Larsen CF, et al: Analysis of carpal instability: I. Description of the scheme. J Hand Surg Am 20(5):757-764, 1995 34. Short WH, et al: Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: Part III. J Hand Surg Am 32(3):297-309, 2007 35. Brunelli GA, Brunelli GR: A new technique to correct carpal instability with scaphoid rotary subluxation: A preliminary report. J Hand Surg Am 20(3 Pt 2):S82-S85, 1995
9 36. Salva-Coll G, et al: The role of the flexor carpi radialis muscle in scapholunate instability. J Hand Surg Am 36(1):31-36, 2011 37. Guss MS, Bronson WH, Rettig ME: Acute scapholunate ligament instability. J Hand Surg Am 40(10):2065-2067, 2015 38. Whipple TL: The role of arthroscopy in the treatment of wrist injuries in the athlete. Clin Sports Med 17(3):623-634, 1998 39. Whipple TL: The role of arthroscopy in the treatment of wrist injuries in the athlete. Clin Sports Med 11(1):227-238, 1992 40. Wahegaonkar AL, Mathoulin CL: Arthroscopic dorsal capsuloligamentous repair in the treatment of chronic scapho-lunate ligament tears. J Wrist Surg 2(2):141-148, 2013 41. Del Pinal F: Arthroscopic volar capsuloligamentous repair. J Wrist Surg 2 (2):126-128, 2013 42. Darlis NA, Weiser RW, Sotereanos DG: Partial scapholunate ligament injuries treated with arthroscopic debridement and thermal shrinkage. J Hand Surg Am 30(5):908-914, 2005 43. Hirsh L, et al: Arthroscopic electrothermal collagen shrinkage for symptomatic laxity of the scapholunate interosseous ligament. J Hand Surg Br 30(6):643-647, 2005 44. Blatt G: Capsulodesis in reconstructive hand surgery. Dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna. Hand Clin 3(1):81-102, 1987 45. Berger RA, Bishop AT, Bettinger PC: New dorsal capsulotomy for the surgical exposure of the wrist. Ann Plast Surg 35(1):54-59, 1995 46. Moran SL, et al: Capsulodesis for the treatment of chronic scapholunate instability. J Hand Surg Am 30(1):16-23, 2005 47. Szabo RM: Scapholunate ligament repair with capsulodesis reinforcement. J Hand Surg Am 33(9):1645-1654, 2008 48. Gajendran VK, et al: Long-term outcomes of dorsal intercarpal ligament capsulodesis for chronic scapholunate dissociation. J Hand Surg Am 32 (9):1323-1333, 2007 49. Lavernia CJ, Cohen MS, Taleisnik J: Treatment of scapholunate dissociation by ligamentous repair and capsulodesis. J Hand Surg Am 17 (2):354-359, 1992 50. Uhl RL, et al: Dorsal capsulodesis using suture anchors. Am J Orthop 26 (8):547-548, 1997 51. Pomerance J: Outcome after repair of the scapholunate interosseous ligament and dorsal capsulodesis for dynamic scapholunate instability due to trauma. J Hand Surg Am 31(8):1380-1386, 2006 52. Rosenwasser MP, Miyasajsa KC, Strauch RJ: The RASL procedure: Reduction and association of the scaphoid and lunate using the Herbert screw. Tech Hand Up Extrem Surg 1(4):263-272, 1997 53. Koehler SM, Guerra SM, Kim JM, et al: Outcome of arthroscopic reduction association of the scapholunate joint. J Hand Surg Eur Vol 41 (1):48-55, 2016 54. Caloia M, Caloia H, Pereira E: Arthroscopic scapholunate joint reduction. Is an effective treatment for irreparable scapholunate ligament tears? Clin Orthop Relat Res 470(4):972-978, 2012 55. Larson TB, Stern PJ: Reduction and association of the scaphoid and lunate procedure: Short-term clinical and radiographic outcomes. J Hand Surg Am 39(11):2168-2174, 2014 56. Van Den Abbeele KL, et al: Early results of a modified Brunelli procedure for scapholunate instability. J Hand Surg Br 23(2):258-261, 1998
KEYWORDS Scapholunate ligament, Acute injury, Wrist instability, Carpal instability, Wrist sprain
Types of Carpal Instability
C
arpal instability can be classified into 4 major patterns: carpal instability dissociative (CID), carpal instability nondissociative (CIND), carpal instability complex, and carpal instability adaptive.1 CID occurs when there is injury between the bones of the same carpal row by fracture or ligamentous disruption, such as a scapholunate ligament (SL) injury, in contrast to CIND, which occurs when there is dysfunction between 2 rows such as between the distal radius and proximal carpal row or between carpal rows.2 When CID and CIND coexist, it is classified as carpal instability complex; an example of which would be a perilunate dislocation.3 Finally, if the origin of carpal instability lies outside of the carpus (proximal or distal), the pattern of instability is known as carpal instability adaptive, for example, instability secondary to a distal radius malunion.4 Tears in the scapholunate interosseous ligament (SLIL) are the most commonly encountered intercarpal ligament injury with an incidence of up to 20% in “sprained” wrists and as high as 21.5%-54% after displaced distal radius fractures. This could lead to a proximal CID collapse pattern. Following the tear, the scaphoid has a tendency to flex around the palmar radioscaphoidcapitate ligament secondary to palmar torque from the scaphotrapezio-trapezoid (STT) articulation. Conversely, the lunate has a tendency to extend secondary to the
*Department of Surgery, University of Montreal, Montréal, Québec, Canada. †Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN. Address reprint requests to Sanjeev Kakar, MD, Department of Orthopedic Surgery, Mayo Clinic, 200 First St SW, Rochester, MN 55905. E-mail: [email protected]
http://dx.doi.org/10.1053/j.otsm.2016.02.002 1060-1872//& 2016 Elsevier Inc. All rights reserved.
extension moment transmitted by the triquetrum via the lunotriquetral ligament. As the secondary stabilizers of the scapholunate joint become attenuated, that is, the volar radioscaphocapitate (RSC) ligament, the short radiolunate and long radiolunate (LRL) ligaments, the dorsal intercarpal (DIC), the STT, and the dorsal radiotriquetral ligaments, dorsal intercalated segment instability (DISI) deformity ensues.5 Scapholunate instabilities can also be classified as predynamic, dynamic, or static. If the injury causes only partial SLIL tear, it would appear as predynamic instability with normal radiographs, (including stress views) but may have some magnetic resonance imaging (MRI) and arthroscopic evidence of SLIL tear. On the contrary, as the tear progresses, a dynamic (seen on stress views) and eventual static instability (visible on standard unstressed radiographs) can ensue.1 Despite being the most common interosseous ligamentous wrist injury, the natural history of SL tears is not clearly understood. Many of these injuries go undetected. Watson studied 4000 wrist radiographs and identified 210 cases of wrist arthritis. The evolution of arthritis in the scapholunate advanced collapse (SLAC) pattern was then proposed by his findings.6 Arthritis starts at the radial styloid and progresses to include the radioscaphoid articular surface. As the SL interval widens, the head of the capitate migrates proximally into the widened interval, resulting in arthritic changes at the lunocapitate joint6 (Fig. 1). O’Meeghan et al7 evaluated 11 patients with arthroscopicproven SLIL injuries without any radiographic evidence of SL gapping or secondary osteoarthritis, and noted that in the absence of complete dissociation of the scapholunate, there would not be an eventual widening of the SL interval or DISI deformity within a 7-year follow-up period. Only 1 out of the 1
2
A. Izadpanah, S. Kakar Selective sectioning studies by Werner et al13 have established that the SLIL is the primary stabilizer of this complex, and the secondary stabilizers are responsible for stabilizing the SL at the extremes of motion. In a cadaveric model, increasing rotatory subluxation of the scaphoid led to a progressive decrease of the articular contact surface area (201 scaphoid subluxation caused a 77% reduction in the articular contact).14 The most common mechanism of SL injury as originally described by Mayfield et al15 is a fall on an extended, ulnarly deviated, and supinated wrist. Given the relative strength of the dorsal SL ligament, these tears tend to start palmar and propagate dorsal. This is the basis for progressive SL instability from predynamic to eventual static deformity with a fixed flexed scaphoid and an extended lunate.
History and Physical Examination Figure 1 Scapholunate advanced collapse (SLAC) wrist arthritis. There is evidence of scapholunate diastasis with radioscaphoid and midcarpal arthritis, and proximal migration of the capitate.
11 patients developed radiographic arthritis, but all patients developed chronic wrist pain affecting their activities of daily living.7
Relevant Anatomy and Biomechanics of Injury The SLIL is a true intra-articular ligament bathed in synovial fluid with poor intrinsic healing potential.8 It comprises a dorsal, membranous, and a palmar segment. The dorsal segment is the strongest of the 3 with a yield strength of 260 N and fibers that are transverse and parallel. The fibers of the palmar segment are obliquely oriented with a yield strength of 120 N. The membranous portion has a yield strength of 65 N and is largely made of anisotropic fibrocartilage, blending in with the articular cartilages of the scaphoid and lunate.9,10 (Fig. 2). The SL ligament is highly innervated with proprioceptive receptors including Pacini (perceiving acceleration and deceleration) and Ruffini (perceiving joint positioning) receptors that contribute to dynamic joint positioning.11 The palmar subregion of SLIL contains the greatest amount of neural structures and mechanoreceptors compared to the dorsal subregion, which is predominantly comprised of densely packed collagen fibers with limited innervation.11 The motion of the carpus is complex. The proximal row acts as the intercalated segment within the wrist and is devoid of any musculotendinous insertions. Its movement is determined by the complex interactions of the forearm and the distal carpal row. Many of the adjacent carpal ligaments act as critical components in SL stability, in particular, the STT and the RSC ligaments.12
Patients may complain of weakness and dorsal radial wrist pain during loading of the extended wrist after a wrist injury. Associated pain may limit their range of motion (ROM) and grip strength affecting different activities of daily living, that is, lifting heavy objects, grocery shopping, or using a screwdriver. Given this, many patients may have to adapt to their lifestyles.7 On examination, in an acute injury, there may be swelling, ecchymosis, and pain over the dorsoradial aspect of the wrist. This area can be found just distal to Lister tubercle with the wrist in a partially flexed position. A positive Watson scaphoid shift test (pain over the dorsal scaphoid with radial deviation of the wrist and a dorsally directed force on the scaphoid tuberosity) could indicate a complete or near-complete disruption of the dorsal portion of SLIL. The palpable click during this maneuver test is secondary to the scaphoid shifting in relation to the remaining carpal bones. Frequently, a clunk can be felt when releasing the force as the scaphoid relocates from the dorsal rim of distal radius into the radioscaphoid fossa. This should be compared with the contralateral side. A unilateral Watson shift test is associated with an increased risk of SLIL injury, with positive and negative likelihood ratios of 2.9 and 0.28, respectively.16,17
Imaging, Diagnosis, and Classifications After a detailed history and examination, initial investigation should commence with posteroanterior and lateral plain wrist radiographs. This should be examined for any carpal fracture and increased SL diastasis and angle. Plain radiographs are often normal with dynamic instability. Given this, stress views are advocated as they may demonstrate abnormal widening of this interval. In a cadaveric study by Lee et al investigating different stress views (the “clenched pencil” view, clenched fist views in varying positions, and traction views) (Fig. 3), the “clenched pencil” view was considered the best stress view to demonstrate dynamic SL instability18 (Fig. 4). It is important to obtain radiographs of the contralateral wrist, as bilateral SL
Acute Scapholunate Injuries
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3
B
Figure 2 Image demonstrating the scapholunate ligament and its attachments to the scaphoid and lunate. (Adapted with permission from Berger et al.10) Copyright 2011 American Society for Surgery of the Hand.11 (Adapted with permission from Elsevier).
diastasis can be a normal variant.19,20 Although patients with widened SL interval on plain radiographs are considered to have static instability (implying damage to both SLIL and secondary stabilizers), up to 50% of normal wrists can have an SL interval distance of 44 mm.20 Having the SL interval width set at 2.5 mm, the sensitivity for detecting a true SLIL lesion is only 60%, the specificity is 75%, and the positive likelihood ratio is 2.41.21 Given this, it is important to
A
weigh the radiographic findings with a clinical suspicion of SL injury. To aid in its diagnosis, advanced imaging may be required. Weiss et al22 investigated the role of wrist arthrography and demonstrated up to 74% incidence of bilateral articular communications between midcarpal and radiocarpal joint spaces despite unilateral symptoms (false negative); only 10% of arthrograms showed communications correlating with
B
Figure 3 Image demonstrating the unstressed (A) and stressed “clenched fist” (B) views with SL interval widening; arrows are pointing to the SL interval.
A. Izadpanah, S. Kakar
4 pain localization (true positive). However, using concomitant fluoroscopy and arthrography can increase the sensitivity of the study up to 60% and the specificity to almost 100%. This would translate into an accuracy of 84% when compared with wrist arthroscopy as the gold standard.22 With static SL injuries, normal alignment of the carpus would be disrupted. The normal scapholunate angle (301-601) increases to greater than 601 secondary to scaphoid flexion and lunate extension. Additionally, the lunocapitate angle increases to greater than 101 with dorsal translation of capitate. On posteroanterior wrist x-rays, scaphoid flexion could also lead to the “scaphoid ring sign” secondary to the flexion of the scaphoid causing the overlap of the distal and proximal poles to appear as a ring. High-resolution (3.0 T) MRIs have demonstrated a sensitivity range of 70%-81% and specificity near 100% with a positive predictive value of 97%-100% in diagnosing SL injuries.23 Magnetic resonance arthrograms compared to plain MRIs have been demonstrated to be more sensitive to SL tears24-26 (Fig. 5). Wrist arthroscopy is considered to be the gold standard for diagnosis, especially in early predynamic and dynamic stages where other imaging studies may be inconclusive. Geissler et al27 in 1996 advocated for the use of both radiocarpal and midcarpal portals during wrist arthroscopy to increase the sensitivity to diagnose SL injuries (Table 1) (Fig. 6). Although many studies have demonstrated good correlation between Geissler grading and the degree of ligamentous tear, there are some limitations to its use.28,29 The original grading system was derived from patients with displaced intra-articular distal radius fractures. It has not yet been validated in patients without a traumatic wrist injury to identify its intraobserver and interobserver reliabilities.30 Rimington et al conducted a study in 83 fresh-frozen cadavers devoid of any previous wrist trauma to assess the validity of Geissler classification. It was noted that the study showed the poor correlation between the grades of laxity in the SLIL ligament, the SL interval, and the angle. Given these findings, the authors
Figure 5 Axial MRI showing volar SL tear. (Color version of figure is available online.)
concluded that this classification may help in describing intercarpal ligamentous laxity rather than diagnosing pathologic instabilities.31 Lee et al28 conducted a cadaveric study correlating the degree of Geissler grading to SL diastasis. It was noted that Geissler grade II was associated with SL sectioning only. Geissler grade III developed after division of the dorsal SLIL and continued sectioning of the volar extrinsic ligaments. Geissler grade IV diastasis occurred after sectioning of both SLIL and all of the dorsal extrinsic ligaments.28. These findings may be of use when determining the type of surgical reconstructions for this injury. In a similar attempt to correlate the arthroscopic findings with the degree of ligament injury, Messina et al described the European Wrist Arthroscopy Society classification. This is an anatomical-pathological classification based on sectioning of different portions of SLIL (Table 2). The authors identified different stages of SL injury that would contribute to scapholunate dissociation (SLD).29 Cadaveric dissections demonstrated that the SL gap increased after additional sectioning of at least 2 secondary stabilizers (RSC or LRL volarly and DIC dorsally). The diastasis increased significantly with sectioning of other extrinsic ligaments.29,31
Treatment
Figure 4 Image demonstrating the “clenched pencil” view adapted with permission from Lee et al.28 Copyright 2011 American Society for Surgery of the Hand (Adapted with permission from Elsevier). (Color version of figure is available online.)
A practical algorithm to help guide the surgical treatment of SL injuries was devised by Garcia-Elias et al32 (Table 3). It comprises several factors that collectively need to be considered to guide the optimal treatment. The first is the integrity of the dorsal SLIL. Partial SLIL tears tend to involve the palmar and membranous portion with the dorsal component remaining intact. In the context of an intact dorsal ligament, the scaphoid shift test may be negative, the arthrogram inconclusive, but a high-resolution MRI or magnetic resonance arthrograms or wrist arthroscopy might be able to identify the potential volar or membranous segments tears. Next is the healing potential of the ligament; acute avulsion type injuries have a greater propensity to heal when compared with chronic mid substance ruptures that are less likely to heal without surgical intervention.33 Third is the status of the secondary stabilizers12,34; dorsal and volar STTs, DIC,
Acute Scapholunate Injuries
5
Table 1 Geisslers Arthroscopic Grading of Scapholunate Interosseous Ligamentous Injuries Grade Description I II III IV
Attenuation/hemorrhage of interosseous ligament as seen from the radiocarpal joint. No incongruency of carpal alignment in the midcarpal space. Attenuation/hemorrhage of interosseous ligament seen through radiocarpal portals. Step-off seen from midcarpal portals. A slight gap (less than width of a probe) between carpals may be present. Step-off of carpal alignment is seen through both radiocarpal and midcarpal portals. The probe may be passed through the gap between carpals. Step-off of carpal alignment seen in both the radiocarpal and midcarpal portals. Gross instability with manipulation is seen and a 2.7 mm arthroscope may be passed through the gap between carpals (drive-through sign).
dorsal radiotriquetral, short radiolunate, LRL, and scaphocapitate ligaments. These help to maintain the scaphoid’s alignment preventing the rotatory subluxation of the scaphoid after a complete SL disruption. Fourth is whether the carpus is malaligned and whether it can be reduced into its anatomical position. This is an important factor influencing the decision for soft tissue reconstructions. With chronic injuries, fibrosis can develop and prevent reduction of the scapholunate joint. The location of this fibrosis tends to be at the palmar and proximal edge of lunate and the medial corner of the scaphoid tuberosity.35 If the carpus cannot be easily reduced, soft tissue reconstructions may fail.32 The last component that needs to be considered is the state of the articular cartilage of the carpus.6 If there is evidence of degenerative changes, SLIL reconstructions are contraindicated, and one should proceed to more salvage-type procedures such as a scaphoid excision and 4-bone fusion.32
Nonoperative Management Treatment Numerous muscles have been shown to affect SL kinematics including the flexor carpi radialis (FCR), flexor carpi ulnaris, extensor carpi radialis brevis (ECRB), extensor carpi radialis longus, and abductor pollicis longus. Garcia-Elias suggests that in the presence of predynamic or dynamic instabilities, the FCR and ECRB may be able to stabilize the SLIL through
strengthening and proprioceptive training. The ECRB acts to stabilize the lunate by promoting extension and placing volardirected pressure on the capitate counteracting the extension of the lunate. The FCR, in return, generates a dorsal and supination vector that resists the scaphoid from rotating into flexion and pronation.36 It is worth noting, however, that in a complete SLIL tear, the forces exerted by FCR could potentially induce a dorsal translatory force leading to further subluxation of the proximal pole of scaphoid. The role of conservative management in treatment of SLIL injuries is controversial. O’Meeghan proposed nonsurgical management for grade I (minor) SL ligament injuries. However, it should be noted that all patients in the report had some level of pain, decreased grip strength, and ROM with difficulties for activities such as grocery shopping and other activities of daily living; many had to change lifestyle and work.2 In our practice, for acute predynamic injuries, we attempt a period of wrist immobilization followed by FCR and ECRB strengthening.
Operative Management There have been a number of surgical techniques described for the treatment of SL injury. They are limited to case reports and retrospective series with limited power and validity to advocate one treatment over the next. What follows is a review of some of the more popular surgical techniques and their outcomes.
Surgical Techniques Reduction and Ligamentous Repair Acutely diagnosed SL injuries may fall into Garcia-Elias stage 1 or 2 SLD. The ligament is usually avulsed off of the scaphoid and may be reparable. Different techniques for primary repair of SLIL tears have been proposed, ranging Table 3 Staging of Scapholunate Dissociations (SLD) Devised by Garcia-Elias33 Stage Figure 6 Midcarpal view of the scapholunate interval showing Geissler grade 3 volar diastasis. Scaphoid is on the right and lunate on the left. Probe passing through the scapholunate interval with no evidence of degenerative changes in the distal scaphoid or lunate. (Color version of figure is available online.)
Intact SLIL Reparable SLIL Normal alignment Reducible Normal articular
1
2
3
4
5
6
Yes Yes Yes Yes Yes
No Yes Yes Yes Yes
No No Yes Yes Yes
No No No Yes Yes
No No No No Yes
No No No No No
A. Izadpanah, S. Kakar
6 Table 2 Arthroscopic EWAS Classification and the Corresponding AnatomoPathological Findings EWAS Arthroscopic Stage I. II. (lesion of membranous SLIL) III A. (partial lesion involving volar SLIL) III B. (partial lesion involving dorsal SLIL) III C. (Complete SLIL tear and joint is reducible) IV. (Complete SLIL tear with SL gap) V.
SLIL Test From Midcarpal Joint No passage of probe Passage of probe tip without widening (stable) Volar widening on dynamic testing
AP Radiographs Findings Not found Lesion of proximal/membranous SLIL
Lesion of anterior and proximal SLIL with/without lesion of RSC-LRL Dorsal widening on dynamic testing Lesion of dorsal and proximal SLIL with partial dorsal intercarpal ligament tear Complete widening on dynamic testing; Complete lesion of SLIL with 1 extrinsic ligament (DIC or Reducible on probe removal RSC/LRL) SL gap with passage of probe from Complete lesion of SLIL and extrinsic ligaments (DIC midcarpal to radiocarpal and RSC/LRL) Wide SL with passage and DISI deformity Complete lesion of SLIL and extrinsic plus one or more other ligaments (TH, ST, and DRC)
AP, anteroposterior; DIC, dorsal intercarpal ligament; DRC, dorsoradiocarpal; RC, radiocarpal; ST, scaphotrapezial; TH, triquetrohamate.
from arthroscopically assisted reduction and pinning to open dorsal approach and stabilization using suture anchors or transosseous sutures with comparable results.37 Whipple38 described the role of arthroscopy in the reduction and transcutaneous pin stabilization of acute SL injuries.39 Whipple reviewed the results of arthroscopic management of scapholunate instability after a follow-up duration of 1-3 years. Patients were divided into 2 groups depending on the time since injury and SL diastasis. It was noted that 83% of patients had good results if their treatment was within 3 months of injury with a SL gap of less than 3 mm. In
A
D
contrast, only 53% of patients undergoing arthroscopic reduction and pinning after 3 months with more than 3 mm SL interval had symptomatic relief. Wahegaonkar and Mathoulin reported on repair of SL injuries with an arthroscopic-assisted dorsal capsulodesis. A total of 57 consecutive patients with Garcia-Elias stages 24 SL injury were treated with a mean time to injury of 10 months and follow-up of 31 months. The mean postoperative grip strength of the operated side was 93.4% when compared with the unaffected side. The DISI was corrected in all cases on postoperative radiographs, and the mean difference between
C
B
E
F
Figure 7 Arthroscopic-assisted volar capsuloligamentous repair. (Adapted with permission from del Pinal.41 Copyright thieme (Permission requested). (Color version of figure is available online.)
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Capsulodesis
Figure 8 Berger’s capsulodesis. Image adapted with permission from Michelotti BF, et al: Chronic scapholunate ligament injury: Technique in repair and reconstruction. Hand Clin 31(3):437-449, 2015; Copyright 2015 Elsevier Inc. (Adapted with permission from Elsevier).
the postoperativeand preoperative SL angles was 8.951. The Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) scores had improved to 8.3 from 46. The average grip strengths had increased by 14 kg from 24 kg preoperatively and with an improvement in preoperative pain scores.40 Del Pinal41 reported on the role of all-inside arthroscopic suturing technique for the repair of volar SL or the plication of space of Poirier (Fig. 7). Using the midcarpal portals, a 22gauge needle is inserted from volar to dorsal immediately ulnar to the FCR, 1 cm proximal to the distal wrist crease. After appropriate positioning, a Tuohy needle is inserted through the same pathway and a 2-0 polydioxanone suture is threaded through and pulled through the radial midcarpal portal. The needle is then retracted from the capsule, while remaining subcutaneously, and slid just distal to the palmar edge of the scaphoid. The suture is then again inserted and grasped via the radial midcarpal portal and using a sliding knot, is secured to close the palmar diastasis by imbricating the SL and LRL ligament.41 The use of thermal shrinkage for the management of ligamentous injuries has been shown to have some promise. Darlis et al in 2004 described the use of arthroscopic debridement and thermal shrinkage for the treatment of partial SLIL tears. In total, 14 patients with tears involving the volar and membranous segments of the SL ligament were treated. Further, 8 patients had excellent relief (complete relief of symptoms), 6 good, 1 fair, and 1 poor.42 Hirsh et al evaluated the outcome of patients with Geissler grade II who underwent electrothermal shrinkage; 2 patients had presented within 6 weeks of injury, whereas the remainder presented after 6 weeks following the injury. At final follow-up at 28 months, 9 patients (90%) were asymptomatic with return to normal preoperative activities.43
Capsulodesis is a procedure designed to use a portion of the dorsal capsule to control the position of the carpus. It can be used as an augmentation after primary ligamentous repair or the definitive reconstructive procedure. Blatt44 described a procedure that involved a proximally based strip of dorsal capsule tethered onto the dorsal scaphoid to prevent scaphoid flexion. The scaphoid is temporarily pinned to the capitate with Kirschner wires for 12 weeks before it is removed and ROM exercises started. Blatt reported on the outcome of this technique in 12 patients with “gratifying” results. Full recovery of wrist extension and less than 201 of wrist flexion loss with an average recovery of 80% of grip strength was achieved in this group.44 Berger et al45 later described a modification of capsulodesis technique using a distally based strip of the DIC ligament tethered to the dorsal lunate. The DIC is detached from the triquetrum and sutured to the dorsal-proximal corner of the lunate after reduction of the scaphoid (Fig. 8). Moran et al in 2005 reported on the intermediate-term outcome of dorsal capsulodesis techniques using both Blatt’s (11 patients) and Berger’s (20 patients) modifications for chronic SL dissociations. A total of 18 patients had dynamic instability, 13 had static deformity, and time from injury to surgery averaged 20 months. There was a 20% decrease in wrist range of motion, no change in grip strength with 58% of patients having mild to no pain, 21% had moderate pain, and 21% continued to complain of pain with activities. Further, 4 patients had to permanently change employment and 2 underwent salvage procedures. Time to surgery had no effect upon outcome, and at a final follow-up of 54 months, the average SL interval increased from 2.7 mm preoperatively to 3.9 mm postsurgery and the SL angle averaged 621.46 A modification of the DIC capsulodesis was proposed by Szabo47 who transposed the ligament from the trapezium and trapezoid and transferred it to the distal pole of scaphoid. A total of 15 patients were followed up for over 5 years. At final followup, patients had an average DASH score of 19 and 78 on the SF-12.48 The average SL angle was 621 and SL gap of 3.5 mm. Also, 58% of patients maintained a high degree of functionality, with half of all patients developing radiographic arthritis. Similar reports have shown high rates of satisfaction and symptomatic improvement in up to 80% of patients without a significant improvement in the SL interval or angle.49-51
Reduction and Association of Scaphoid and Lunate The reduction and association of scaphoid and lunate (RASL) procedure is designed to create a pseudoarthrosis between the scaphoid and lunate.52 The articular surfaces between the scaphoid and lunate are debrided and after the joint is reduced, a cannulated smooth compression screw is placed between them. The screw is either left in situ or removed after several months of healing.52 Koehler et al53 reported on an arthroscopic-assisted RASL procedure in 18 patients with chronic SL instability. After an
A. Izadpanah, S. Kakar
8 average follow-up of 3 years, the mean visual analog pain score was 2.5, DASH score of 8, and the grip strength averaged 84% of the uninjured wrist. A total of 4 patients underwent revision surgery. The authors noted that patients who had an SL gap of 5 mm and stage 1 SLAC wrist arthritis were poor candidates for this procedure. Caloia et al54 reported the outcome of 9 wrists undergoing arthroscopic RASL and found the grip strength to be improved at the final follow-up to 78% of the contralateral side and the arc of motion to be 1071. The average postoperative wrist ROM was 1071, 20% less than the preoperative ROM. The SL angle decreased from 70.51-59.31, and in 3 cases, the screws were removed owing to the loosening or symptomatic complaints. The visual analog pain score was improved from 5.4 preoperatively to 1.5 at last follow-up to 1.5 from a rated value of 5.4 preoperatively. Stern and Larson reported on the outcome of 8 wrists after RASL at 38 months follow-up using 3.0 mm headless cannulated compression screws. In all, 5 wrists had dynamic SL instability and 2 had static instability with an average time of 5 months (range: 1-17 months) from injury for all patients, with the exception of 1 patient who was injured several years ago. All patients were immobilized for 6 weeks in a thumb spica cast after surgery with strengthening exercises starting at 10-12 weeks.55 Authors reported that the SL interval decreased from 2.9 mm preoperatively to 2.2 mm immediately after surgery. At final follow-up, the SL interval was found to be 4.5 mm. Radiographic success (defined by maintenance of corrected SL diastasis, absence of DISI, and no progression of SLAC) was achieved in 3 of the 8 wrists. A patient developed radioscaphoid arthritis. The DASH and patient-rated wrist evaluation outcome questionnaires completed at final followup demonstrated an average DASH of 15 and patient-rated wrist evaluation score of 26. The grip strength averaged at 77% of the contralateral side, and the total active wrist arc of motion for flexion-extension at final follow-up had measured 991 when compared with 1081 preoperatively. Given these poor results, the authors advocated caution with this procedure.55
Ligament Reconstruction Techniques Three-Ligament Tenodesis In 1995, Brunelli and Brunelli35 proposed a technique during which the FCR tendon was used to stabilize the SL interval. During this procedure, a longitudinal slip of FCR (third in cross section) was harvested and tunneled volar to dorsal from the distal pole parallel to the distal articulation of scaphoid and then tightened to correct the scaphoid flexion by tethering the FCR to distal radius. Van Den Abbeele et al56 reported on a modification of this technique in 22 patients. In this technique, the FCR tendon, having been passed from volar to dorsal through the scaphoid, is looped under or though the dorsal radiolunotriquetral ligament and secured to the lunate. By not crossing the radiocarpal joint, the theory was that the wrist ROM would be preserved. The authors reported overall promising results in 17 of 22 patients with relief of pain and restoration of grip strength. Postoperative ROM was reduced in extension and flexion, remained unchanged for radial
deviation, and improved for ulnar deviation. The radiological appearance of dynamic or static scapholunate instability did not change after the procedure.56 Garcia-Elias reported results of 3 ligament tenodesis reconstruction at an average of 46 months follow-up in 38 patients with SLD. In total, 21 wrists showed Garcia-Elias stage 3, 8 had stage 4, and 9 had stage 5. A total of 29 patients in his series had returned to their normal activities, 7 had to downgrade their usual daily activities, and 2 had retired at the end of follow-up. The average ROM at final follow-up was 511 for flexion, 521 for extension, 151 for radial, and 281 of ulnar deviation. The average grip strength at final follow-up was only 65% of the contralateral without any evidence for scaphoid necrosis because of the bone tunneling. In total, 9 patients progressed to early stages of SLAC at final follow-up.32 The authors recommended this procedure for those who have reducible SL deformity comprising stages 3-4 SL instability.
Summary Scapholunate injuries are the most common interosseous carpal injuries that if left untreated, can lead to SLAC. Management of scapholunate dissociations despite being the most common carpal malalignment remains controversial. Conservative management may be considered in early stages of acute SLIL tears with wrist arthroscopy and surgical repair or reconstruction reserved for acute dynamic and static instabilities.
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