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Bone–Tissue–Bone Repairs for Scapholunate Dissociation
REVIEW ARTICLE Bone–Tissue–Bone Repairs for Scapholunate Dissociation Edward J. Harvey, MD, Richard A. Berger, MD, PhD, A. Lee Osterman, MD, Diego L. Fernandez, MD, Arnold-Peter Weiss, MD From the Department of Surgery, Division of Orthopedic Surgery, McGill University Health Centre, Montréal, Canada; Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN; Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, PA; Department of Orthopaedic Surgery, Kantonsspital Aarau, Switzerland; and the Department of Orthopaedics, Brown Medical School, Providence, RI.
Scapholunate dissociation is a commonly seen and treated form of carpal instability. Several surgical options have been used for the repair of scapholunate instability over the past 50 years. These have included benign neglect, reduction and percutaneous pinning, primary repair, partial fusions, tendon weaves, and combinations of these. Recent advancements in scapholunate repair and anatomy have been aimed at a more physiologic repair. Composite replacement of the entire scapholunate interval, similar to other tendon repairs seen in orthopedic surgery, has become popular. Bone–tissue– bone (BTB) autograft replacement from the foot has been used but the problems of a secondary surgical site have resulted in other graft site selections. Currently more commonly used grafts are bone–retinaculum– bone, third or second metacarpal– carpal bone, or hamate– capitate grafts, all performed with or without screw augmentation. Vascularized autograft replacement on pedicled grafts from the hand is being explored. This review discusses the surgeons’ indications and technical details of the surgery. The lack of long-term outcome measurements for these BTB surgeries makes it difficult for the hand surgeon to determine the appropriate use of these treatment modalities, but early reports have indicated that the BTB graft will be an important part of scapholunate dissociation treatment. (J Hand Surg 2007;32A:256 –264. Copyright © 2007 by the American Society for Surgery of the Hand.) Key words: Scapholunate dissociation, wrist, autograft, DISI, ligament.
capholunate dissociation is arguably the most common form of carpal instability.1– 4 Rotatory subluxation of the scaphoid produces well-documented degenerative changes in the wrist.4 – 8 Treatment for the acute dislocation is aimed at regaining the normal anatomy through either maintenance of reduction in a cast after percutaneous pinning, or surgical anatomic reduction and repair of the ligamentous relationships.5,9 –36 Several different approaches for the management of acute dissociation exist, but there is general dissatisfaction with the outcomes after acute repair of the scapholunate interosseous ligament (SLIL). Classic articles reviewing acute repair were not rigorous in outcome measurements— either radiographic or functional.7,37 The treatment of chronic dissociation is even more controversial. Previously, the most common surgical option for
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dissociation was intercarpal fusion.38 This is an option that seems to be far from ideal because patients have decreased range of motion and strength rating. Fusions do not restore normal wrist kinematics and eventually may lead to additional wrist arthrosis. In the absence of degenerative changes in the carpal bones, the optimal treatment would be anatomic restoration of the scapholunate ligament; the flexor carpi radialis and the extensor carpi radialis brevis have been used previously.39,40 Other treatment options reported include, but are not limited to, primary repair of the ligament with the possible addition of reinforcing autologous tissue,13,26 capsulodesis,20 scaphoid allograft,12 ligament reconstruction using dorsal periosteum from the radius near Lister’s tubercle,30 or ligament replacement from the foot.41 Tendon repairs and autologous or cadaveric ten-
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don graft augmentation are not without difficulties according to the literature. Balancing the tendon length and maintenance of the bony anatomy are demanding. Capsulodesis has been successful in only some centers, and has been associated with a loss of wrist motion. Allograft replacement has been restricted by the availability of suitable grafts and expense. Instead attention slowly has become centered on the replacement of the dorsal portion of the SLIL. Several biomechanical and anatomic studies have identified this area to be the most structurally and functionally important area of the SLIL.8,42– 47 Replacement of this area is facile through the dorsal extensile approach that currently is used for other repairs. An attempt to achieve a reconstruction that more closely reproduces the dorsal support of the SLIL has generated research into using bone–tissue– bone (BTB) composite grafts.27,30,31,34,41,48 –50 A large body of research is centered on the design use of other tendon grafts in orthopedic surgery, such as the anterior cruciate ligament. The success of a BTB graft in the replacement of this high-demand ligament probably sparked an interest in grafts for the SLIL. Tarsometatarsal joint autograft,27,41 SLIL allograft,5,12 capitohamate ligament composite,42 metacarpal– carpal composite,49 and bone–retinaculum– bone autograft harvested from the dorsal radius30 all have been examined. The biomechanical goal has been a replacement graft with a strength and stiffness approaching that of the SLIL. All of these procedures currently are investigational; however, early to medium-length follow-up reports of these techniques all have been favorable, and one or more BTB grafts undoubtedly will play a part in the future management of SLIL repair.
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straints to differential rotation between the scaphoid and the lunate. The greatest yield strength was found in the dorsal region (260.3 ⫾ 118.1 N), followed by the palmar region (117.9 ⫾ 21.3 N) and the proximal region (62.7 ⫾ 32.2 N). Similar results in other studies44,45 have led to the conclusion that the dorsal portion of the scapholunate ligament is the most important for carpal stability and therefore the best physiologic target for corrective surgery. Technically, this also is appealing because of the easier dorsal approach used to perform the repair. These biomechanical studies also provided other investigators with the ideal strength to aim for in the design of a replacement BTB graft.
Remote Bone–Tissue–Bone Grafts It is only recently that BTB grafts have been used for scapholunate dissociation. Svoboda et al27 reported the biomechanical properties of foot autografts in 1996. The SLIL and 3 cadaveric autograft candidates from the foot were harvested as BTB complexes. Servohydraulic testing until failure compared their stiffness and strength values. Analysis indicated that the stiffness values for the tarsometatarsal ligament and the SLIL were statistically similar; however, the strength values of all 3 autografts from the foot were significantly less than those of the SLIL. Davis et al41 examined an alternate BTB from the foot that more closely approached the characteristics of the SLIL. Although their graft (the dorsal–medial portion of the navicular–first cuneiform ligament) was weaker than the SLIL, they believed it was a good clinical option and continue to perform this surgery. They perform the graft harvest through a 4-cm medial incision with fluoroscopic control. The tibialis anterior is released
The Scapholunate Interval Although the integrity of the scapholunate ligament may not be the only determinant of the scapholunate angle and the resultant arthritic changes of the wrist, it certainly is the most obvious constraint to the scapholunate interval. Several studies have looked at the relative importance of various portions of the scapholunate ligament. Berger et al42,51 studied the material and constraint properties of the dorsal, proximal, and palmar regions of the scapholunate ligament. Determinations of constraint to differential rotation and translation as well as failure strength were made. The dorsal region of the scapholunate ligament offered the greatest constraint to differential translation, whereas both the dorsal and palmar regions showed statistically significant combined con-
Figure 1. Approach for the harvest of the foot-based BTB graft. The navicular-cuneiform site has been shown to be the graft most biomechanically similar to the SLIL (T.A., tibialis anterior; M.M., medial malleolus).
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Figure 2. Bone–retinaculum– bone graft showing the necessary steps in surgery. (A) A large irreparable scapholunate gap (large white arrow) was visualized at the time of surgery in a 49-year-old man. (B) Trough fashioned in the scaphoid (black arrow) and the lunate (white arrow) after the scapholunate interval was reduced anatomically and held in place with K-wire fixation. The K-wires are in the volar portion of the 2 bones to prevent protrusion in the trough. (C) The BTB graft from the dorsal retinaculum was placed in the trough and held in place with 2 small screws. (D) Sufficient K-wire fixation has been placed to maintain the scapholunate angle and the interval on lateral and anteroposterior fluoroscopy. The 2 internal fixation screws are seen well placed within the lunate and the scaphoid. (E) At the 2-year follow-up evaluation the interval has been well maintained without increased arthrosis.
and retracted posteriorly for best access (Fig. 1). They attempt to harvest a graft that is 10 ⫻ 5 ⫻ 5 mm on each side of the joint. The graft is secured in the manner popularized by Weiss31 (Fig. 2). Osterman and Culp have treated 49 patients with the SLIL graft, with an average follow-up period of 2 years (A. Osterman, personal communication, June 2006). They have had several cases of tissue stretching during healing without loss of angulation. In their subgroup of patients with static SLIL, only 1 patient has had graft failure, patients have obtained 80% of motion, and have increased their grip strength by 30%. Of note, they based their treatment options for
a SLIL injury as per Garcia-Elias et al,52 in which complete tears that were irreparable, nonarthritic, dynamic, reducible, and greater than 4 mm usually were treated with a BTB graft (⫾ a temporary bridging screw). Although morbidity of the secondary foot incision has not been reported widely, several investigators34,36,50 have reflected on the dangers of surgery on an otherwise healthy lower extremity. More recently, researchers have reported on other sites used that are remote from the hand. A BTB harvested from the iliac crest has been compared biomechanically with the dorsal SL ligament and believed to be statistically similar.17 Despite several reports on the
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morbidity of an iliac crest bone graft harvest in the literature, perhaps the nature of a BTB graft would minimize these complications.
Isolated Dorsal Retinaculum Grafts Weiss30 first described a BTB from the dorsum of the hand that was harvested near Lister’s tubercle (third extensor compartment base) on the distal radius. Harvesting of the extensor retinaculum and bone block allowed the fashioning of a bone–retinaculum– bone composite graft that was used to reconstruct the dorsal portion of the SLIL. Bone plugs of the graft were fitted into the dorsal scaphoid and the lunate with a retinaculum–periosteal soft-tissue sleeve arching between these 2 bones.31,53 Figure 2 shows the basic surgical technique used in all BTB surgeries. A 49-year-old man with a complete SL tear (Fig. 2A) complained of pain with any loading activity. Intraoperative photographs showed the trough fashioned in the reduced scaphoid and lunate (Fig. 2B) and the graft held in place with 2 small screws (Fig. 2C). Fluoroscopy from the time of surgery showed good reduction of the scapholunate interval (Fig. 2D). At the 2-year follow-up evaluation the patient had no pain with equal grip strength (extension/flexion, 65/50 ft-lb; radial deviation/ulnar deviation, 15/30 ft-lb). Follow-up radiographs from that time (Fig. 2E) showed maintenance of the scapholunate interval. This technique was evaluated over a short-term follow-up evaluation in 19 patients (mainly with dynamic instability). The SLIL was reduced and pinned for 8 weeks with cast immobilization. In the initial clinical series by Weiss,31 14 patients were treated with this technique. The follow-up period averaged 3.6 years. In general, the range of motion decreased slightly from the preoperative values, but grip strength improved and patients were satisfied with the procedure. A second study25 reported on the biomechanical testing of this reconstruction. The BTB and dorsal SLIL specimens were harvested from 6 fresh-frozen human cadaveric forearms. The BTB autograft was significantly weaker than the SLIL. The investigators believed that because the mean cross-sectional area of the dorsal SLIL was more than 3 times as large as that of the BTB autograft, the failure stress (failure force/crosssectional area) of the BTB autograft was not markedly different from that of the dorsal scapholunate ligament. They believed that the BTB autograft was appropriate graft material for scapholunate ligament reconstruction, but that structural parity with the dorsal SLIL ultimately will depend on remodeling and
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hypertrophy during healing. Other investigators54 have looked at the viability of retinacular grafts from the distal radius. An overview of the anatomy of the extensor retinaculum, with radiographic and morphometric measurements, was accomplished.55 Ten cadaver wrists were dissected and the thick portion of the retinaculum and its insertions on the radius in the different extensor compartments were studied. A comparison of dissections with radiographs showed that the radial compartments 1, 2, and 3 were suitable for bone–ligament– bone grafting. The mean compartment length was 11.7 mm for compartment 1, 17 mm for compartment 2, and 7.3 mm for compartment 3. This leaves several options in the distal radius for a BTB graft harvest.
Metacarpal-Carpal–Based Bone–Tissue–Bone Grafts Other investigators began to look at options based within the hand itself that might have better biomechanical characteristics to replace the SLIL. The carpometacarpal bone–ligament– bone complex at the base of the second or third metacarpal was proposed as a replacement for the SLIL.49 These articulations are relatively immobile and therefore were seen as expendable if needed for SLIL reconstruction. Both of these grafts also were obtainable easily through the same dissection used for the SLIL repair. These grafts also provide a cartilaginous replacement for the SLIL interval on both the scaphoid and lunate surfaces. Harvey and Hanel49 performed a biomechanical study of cadaveric-matched SLILs, second metacarpal–trapezoid ligaments, third metacarpal– capitate ligaments, and the dorsal retinaculums. Stiffness and strength were obtained from fresh-frozen specimens tested to failure with a servohydraulic apparatus as performed in previous studies. The second metacarpal–trapezoid ligament and the third metacarpal– capitate ligament most closely approximated the stiffness and strength of the SLIL. The dorsal periosteal retinaculum was significantly less stiff and weaker than the SLIL. These 2 new grafts were seen as desirable graft replacements. Another group of researchers substantiated these findings. The mechanical properties of 2 intracarpal ligaments were compared with those of the dorsal component of the SLIL. Trapezoid–to–second metacarpal and capitate–to–trapezoid ligaments and the dorsal part of the SLIL were obtained as bone–ligament– bone grafts from fresh-frozen cadavers. Servohydraulic testing showed that the capitate–to–trapezoid ligament closely approximated the load to failure and
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and protected as it is traced back to the radial artery (Fig. 4B, C). The dorsal intercarpal ligament is incised and repaired during the procedure. The origin of the artery is dissected back to the radial artery proper, freeing sufficient length origin from the radial artery is freed and the resultant to allow placement of the graft in the trough fashioned on the scaphoid and lunate as per Weiss31 (Fig. 4D). The graft is protected by pinning for 8 weeks, and this is followed up by careful mobilization and return to all activities by 3 months. Figure 3. Radiographs 1 year after SLIL repair with a third metacarpal– carpal autograft. The revascularization phase of healing has resulted in a weakened SLIL and the outcome is a stretched ligamentous graft. Figure courtesy of Dr. G. M. Elder.
stiffness of the dorsal SLIL, whereas the trapezoid– to–second metacarpal ligament was significantly stronger and stiffer than the dorsal SLIL. The investigators believed that these 2 grafts were viable options to replace the dorsal SLIL. A small clinical series with short-term follow-up evaluation has shown the third metacarpal– carpal BTB to be successful.50 This technique has been published and is similar to the technique used by Weiss31 for a dorsal retinacular graft. Personal experience with 25 of these surgeries has shown only a limited number of complications. In general the clinical outcome is good and has been successful in the hands of several surgeons. The 2 main complications are graft pullout, usually from the lunate, and graft stretching, with an increased scapholunate interval but no loss of the scapholunate angle (Fig. 3). Graft pullout occurs from a lack of healing in the patchy vascularized lunate and typically is seen in chronic dissociations or lunate dislocations. Lack of healing eventually results in bone or hardware failure. Stretching of the SLIL replacement occurs after several months, with loss of the tight SLIL interval. Presumably this is caused by the revascularization phase of healing, causing graft weakness.
Vascularized Metacarpal-Carpal–Based Bone–Tissue–Bone Grafts In an attempt to prevent these 2 observed complications a vascularized BTB has been designed and is currently in use. A typical third metacarpal– carpal graft can be harvested based on the radial-sided intermetacarpal artery (Fig. 4A). This artery is lifted
Carpal-Based Bone–Tissue–Bone Grafts After their work with scapholunate biomechanics, Ritt et al55 looked at hand-based BTB options for SLIL replacement. In particular they believed that the capitohamate joint would provide an adequate ligament. The study of the capitohamate joint revealed 3 interosseous ligaments: the dorsal, deep, and palmar interosseous ligaments. Their physical attributes were tested in a computer-controlled multiaxis testing machine. In the intact joint complex, the average dorsopalmar rotational displacement was approximately 9° in each direction. Based on sequential sectioning it was found that the dorsal ligament provided 76% of the rotational resistance with palmar rotation of the capitate and 44% of the translational constraint with palmar translation of the capitate. The deep ligament provided 51% of the rotational resistance with dorsal rotation of the capitate and 63% of the translational resistance with dorsal translation of the capitate. With proximal-distal translation, the dorsal ligament was the most important constraint in each direction. In resisting distraction, each of the 3 ligaments was equally effective. Failure testing showed that the deep ligament was strongest at 289 N, followed by the palmar ligament at 171 N, and the dorsal ligament at 133 N. They have progressed to clinical implementation with the harvest of the dorsal capitohamate joint (excluding the deep and palmar ligaments) as a BTB graft (Fig. 5).56 The BTB is supplemented by a capsulodesis. The patients have protected motion beginning at 4 weeks until pin removal at 8 weeks. Strengthening starts at 3 months and athletes are allowed to return to full activity by 20 weeks. Clinical results have been promising but have yet to be published. Berger performs the BTB graft only if (1) any angular carpal malalignments are reduced easily, (2) there is no degenerative joint disease, and (3) the lunate is not translated ulnarly more than 50% off of the lunate fossa (R. Berger, personal communication, June 2006).
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Figure 4. Vascularized BTB graft from the hand. Based on the intermetacarpal and radial arteries the graft is harvested with a pedicle of sufficient length to allow translation to the trough fashioned in the scaphoid and the lunate. (A) Dorsal approach to harvest the vascularized third metacarpal– carpal BTB. The thin arrow shows the consistent branch of the intermetacarpal artery. This can be traced with careful dissection to the terminal dorsal branch of the radial artery. The large black arrowheads point to K-wires placed on both the radial and ulnar sides of the wrist. The K-wires must be placed volar to avoid protrusion into the fashioned trough in the scaphoid and lunate, but also to avoid injury to the branches of the radial artery. (B) Intraoperative fluoroscopy showing closure of the scapholunate interval with several K-wires. The smaller K-wires delineate the graft harvest site at the third metacarpal– capitate interval. Three K-wires are used at the limits of the harvest site (C) to delineate the resection margins for safety. The fourth corner of the graft has no K-wire placed because this is the region of artery insertion (radial capitometacarpal joint). (C) Superimposed graphics represent important landmarks. The square is the harvest site for the BTB that is based on the intermetacarpal artery system (multiple white arrows). (D) The graft has been harvested (large black arrowhead) and translated proximally to the trough in the scaphoid and the lunate. The white arrows show the ulnar and radial placement of the K-wire fixation for safety of the radial artery. The small white arrowheads trace the vascular pedicle and graft in place within the trough.
Augmented Dorsal Retinaculum Grafts In 1991, Herbert56 first reported the concept of an augmented repair using a Herbert screw (Zimmer Inc, Warsaw, IN). The surgical technique involved open reduction and re-attachment of the ligament to the bone, combined with Herbert screw fixation across the scapholunate joint. The screw was left in situ for 12 to 18 months, allowing sufficient time for ligament healing and restoration of carpal stability. He believed this technique allowed early postoperative wrist motion. Excellent results were achieved in the majority of patients but a subgroup of patients showed increasing carpal collapse deformity. Primary repair has such varied results57 that the failures may have been caused by inherent deficiencies in the
Figure 5. The black arrow shows the capitohamate intercarpal ligaments that are retained as a BTB from a dorsal exposure. Only the dorsal ligament composite is taken, which does not destabilize the carpal relationship.
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Figure 6. Herbert screw augmentation of the BTB graft. (A) After reduction of the widened interval through a dorsal approach the Herbert screw drill is placed percutaneously from the radial side through the scaphoid into the center of the lunate (LUN). The drill must be parallel to the radius joint at the scapholunate ligament. (B) Immediate postoperative view of the repair with 2 small screws holding the BTB in place and the larger Herbert screw spanning the 2 bones. (C) After 1 year the spanning screw has been removed. The lunate screw also has been removed. The interval has been maintained. (D) The lateral view at 1 year also shows maintenance of the scapholunate angle.
primary repair technique. Other surgeons have started to use this Herbert screw technique with a BTB graft for the restoration of ligament continuity. Fernandez has had preliminary clinical experience with this technique (D. Fernandez, personal communication, June 2006). He used the BTB graft used by Weiss30 plus a Herbert screw to treat a small group of patients. Initial reduction of the scapholunate interval is performed with a sharp towel clamp through a dorsal approach. Herbert screw fixation is performed
percutaneously from the radial side. It is important to ensure that the screw is parallel to the distal radius in the anteroposterior view to ensure appropriate flexion without screw loosening and anatomic scapholunate articulation (Fig. 6A). The BTB grafting then is performed in the normal fashion (Fig. 6B). K-wire immobilization is not used. The Herbert screw is removed at 9 months to 1 year (Fig. 6C, D). Fernandez had 80% of his first 20 patients return to their previous working levels when he used Herbert screw
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augmentation (D. Fernandez, personal communication, June 2006). One patient had pullout of the screw and stretching of the ligament, and another patient was left with a fixed dorsal intercalated segment instability deformity. There are several options to repair a SLIL insufficiency. The options discussed in this article encompass the newest approaches to the problem. Unquestionably, the early results for these procedures are excellent compared with other historical options; however, no randomized control groups have been established. The procedures are not technically beyond the scope of all hand surgeons, and except for the vascularized option, are not beyond the capabilities of any orthopedic surgeon. Other surgeons have stated that the reason that these procedures function is because of an arthrodesis between the scaphoid and lunate and that long-term outcomes will be poor. It is unlikely that fusion is the mode of success for these procedures. It is obvious from radiographic studies that there is a clear space between the 2 bones. Also, in a fluoroscopic study performed at our institution, the scaphoid and lunate continued to move in relation to each other. The BTB repair, in whatever form the surgeon chooses, is a good option for scapholunate repair and will be part of the future armamentarium of all hand surgeons. Received for publication July 18, 2006; accepted in revised form November 20, 2006. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Edward J. Harvey, MD, Chief of Hand and Microvascular Surgery, Division of Orthopaedic Surgery, McGill University Health Centre—Montreal General Site, 1650 Cedar Ave, Room B5.159.5, Montreal, Quebec, Canada H3G1A4; e-mail: Edward.harvey@ much.mcgill.ca. Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A02-0019$32.00/0 doi:10.1016/j.jhsa.2006.11.011
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The Journal of Hand Surgery / Vol. 32A No. 2 February 2007 carpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model. J Hand Surg 1999;24A:232–239. Svoboda S, Eglseder W, Belkoff S. Autografts from the foot for reconstruction of the scapholunate interosseous ligament. J Hand Surg 1995;20A:980 –985. Viegas SF, Dasilva MF. Surgical repair for scapholunate dissociation. Tech Hand Upper Extrem Surg 2000;4:148 –153. Watson H, Hempton R. Limited wrist arthrodesis. I. The triscaphe joint. J Hand Surg 1980;5:320 –327. Weiss AP. Scapholunate ligament reconstruction using a bone-retinaculum-bone autograft: a new technique. AAOS Trans 1996;213:169. Weiss AP. Scapholunate ligament reconstruction using a bone-retinaculum-bone autograft. J Hand Surg 1998;23A: 205–215. Weiss AP, Sachar K, Glowacki KA. Arthroscopic debridement alone for intercarpal ligament tears. J Hand Surg 1997; 22A:344 –349. Wintman B, Gelberman R, Katz J. Dynamic scapholunate instability: results of treatment with dorsal capsulodesis. J Hand Surg 1995;20A:971–979. Wolf JM, Weiss AP. Bone-retinaculum-bone reconstruction of scapholunate ligament injuries. Orthop Clin North Am 2001;32:241–246, viii. Wyrick JD, Youse BD, Kiefhaber TR. Scapholunate ligament repair and capsulodesis for the treatment of static scapholunate dissociation. J Hand Surg 1998;23B:776 –780. Zarkadas PC, Gropper PT, White NJ, Perey BH. A survey of the surgical management of acute and chronic scapholunate instability. J Hand Surg 2004;29A:848 – 857. Blatt G. Capsulodesis in reconstructive hand surgery. Dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna. Hand Clin 1987;3: 81–102. Kleinman W, Carrol C. Scapho-trapezio-trapezoid arthrodesis for treatment of static and dynamic scapholunate instability: a ten year prospective on pitfalls and complications. J Hand Surg 1990;15A:408 – 414. Brunelli F, Spalvieri C, Bremner-Smith A, Papalia I, Pivato G. [Dynamic correction of static scapholunate instability using an active tendon transfer of extensor brevi carpi radialis: preliminary report.] Chir Main 2004;23:249 –253. Brunelli GA, Brunelli GR. A new technique to correct carpal instability with scaphoid rotary subluxation: a preliminary report. J Hand Surg 1995;20A:S82–S85. Davis CA, Culp RW, Hume EL, Osterman AL. Reconstruction of the scapholunate ligament in a cadaver model using a bone-ligament-bone autograft from the foot. J Hand Surg 1998;23A:884 – 892.
42. Berger RA, Imeada T, Berglund L, An KN. Constraint and material properties of the subregions of the scapholunate interosseous ligament. J Hand Surg 1999;24A:953–962. 43. Kauer J. Functional anatomy of the wrist. Clin Orthop 1980; 149:9 –20. 44. Short W, Werner F, Fortino M, Palmer A, Mann K. A dynamic biomechanical study of scapholunate ligament sectioning. J Hand Surg 1995;20A:986 –999. 45. Short WH, Werner FW, Green JK, Masaoka S. Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: part II. J Hand Surg 2005;30A:24 –34. 46. Tang JB, Ryu J, Omokawa S, Wearden S. Wrist kinetics after scapholunate dissociation: the effect of scapholunate interosseous ligament injury and persistent scapholunate gaps. J Orthop Res 2002;20:215–221. 47. Viegas SF, Yamaguchi S, Boyd NL, Patterson RM. The dorsal ligaments of the wrist: anatomy, mechanical properties, and function. J Hand Surg 1999;24A:456 – 468. 48. Cuenod P, Charriere E, Papaloizos MY. A mechanical comparison of bone-ligament-bone autografts from the wrist for replacement of the scapholunate ligament. J Hand Surg 2002;27A:985–990. 49. Harvey E, Hanel D. Autograft replacements for the scapholunate ligament: a biomechanical comparison of hand based autografts. J Hand Surg 1999;24A:963–967. 50. Harvey E, Hanel D. What is the ideal replacement for the scapholunate ligament in a chronic dissociation? Can J Plast Surg 2000;8:143–146. 51. Berger RA. The gross and histologic anatomy of the scapholunate interosseous ligament. J Hand Surg 1996;21A: 170 –178. 52. Garcia-Elias M, Lluch AL, Stanley JK. Three-ligament tenodesis for the treatment of scapholunate dissociation: indications and surgical technique. J Hand Surg 2006;31A:125– 134. 53. Harvey EJ, Hanel DP. Bone-ligament-bone reconstruction for scapholunate disruption. Tech Hand Upper Extrem Surg 2002;6:2–5. 54. Werther JR, Guelmi K, Mazodier F, Doursounian L. Use of the extensor retinaculum as a donor site for bone-ligamentbone grafts. Surg Radiol Anat 2001;23:295–299. 55. Ritt MJ, Berger RA, Kauer JM. The gross and histologic anatomy of the ligaments of the capitohamate joint. J Hand Surg 1996;21A:1022–1028. 56. Herbert TJ. Acute rotary dislocation of the scaphoid: a new technique of repair using Herbert screw fixation across the scapho-lunate joint. World J Surg 1991;15:463– 469. 57. Walsh JJ, Berger RA, Cooney WP. Current status of scapholunate interosseous ligament injuries. J Am Acad Orthop Surg 2002;10:32– 42.
Scapholunate dissociation is a commonly seen and treated form of carpal instability. Several surgical options have been used for the repair of scapholunate instability over the past 50 years. These have included benign neglect, reduction and percutaneous pinning, primary repair, partial fusions, tendon weaves, and combinations of these. Recent advancements in scapholunate repair and anatomy have been aimed at a more physiologic repair. Composite replacement of the entire scapholunate interval, similar to other tendon repairs seen in orthopedic surgery, has become popular. Bone–tissue– bone (BTB) autograft replacement from the foot has been used but the problems of a secondary surgical site have resulted in other graft site selections. Currently more commonly used grafts are bone–retinaculum– bone, third or second metacarpal– carpal bone, or hamate– capitate grafts, all performed with or without screw augmentation. Vascularized autograft replacement on pedicled grafts from the hand is being explored. This review discusses the surgeons’ indications and technical details of the surgery. The lack of long-term outcome measurements for these BTB surgeries makes it difficult for the hand surgeon to determine the appropriate use of these treatment modalities, but early reports have indicated that the BTB graft will be an important part of scapholunate dissociation treatment. (J Hand Surg 2007;32A:256 –264. Copyright © 2007 by the American Society for Surgery of the Hand.) Key words: Scapholunate dissociation, wrist, autograft, DISI, ligament.
capholunate dissociation is arguably the most common form of carpal instability.1– 4 Rotatory subluxation of the scaphoid produces well-documented degenerative changes in the wrist.4 – 8 Treatment for the acute dislocation is aimed at regaining the normal anatomy through either maintenance of reduction in a cast after percutaneous pinning, or surgical anatomic reduction and repair of the ligamentous relationships.5,9 –36 Several different approaches for the management of acute dissociation exist, but there is general dissatisfaction with the outcomes after acute repair of the scapholunate interosseous ligament (SLIL). Classic articles reviewing acute repair were not rigorous in outcome measurements— either radiographic or functional.7,37 The treatment of chronic dissociation is even more controversial. Previously, the most common surgical option for
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dissociation was intercarpal fusion.38 This is an option that seems to be far from ideal because patients have decreased range of motion and strength rating. Fusions do not restore normal wrist kinematics and eventually may lead to additional wrist arthrosis. In the absence of degenerative changes in the carpal bones, the optimal treatment would be anatomic restoration of the scapholunate ligament; the flexor carpi radialis and the extensor carpi radialis brevis have been used previously.39,40 Other treatment options reported include, but are not limited to, primary repair of the ligament with the possible addition of reinforcing autologous tissue,13,26 capsulodesis,20 scaphoid allograft,12 ligament reconstruction using dorsal periosteum from the radius near Lister’s tubercle,30 or ligament replacement from the foot.41 Tendon repairs and autologous or cadaveric ten-
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don graft augmentation are not without difficulties according to the literature. Balancing the tendon length and maintenance of the bony anatomy are demanding. Capsulodesis has been successful in only some centers, and has been associated with a loss of wrist motion. Allograft replacement has been restricted by the availability of suitable grafts and expense. Instead attention slowly has become centered on the replacement of the dorsal portion of the SLIL. Several biomechanical and anatomic studies have identified this area to be the most structurally and functionally important area of the SLIL.8,42– 47 Replacement of this area is facile through the dorsal extensile approach that currently is used for other repairs. An attempt to achieve a reconstruction that more closely reproduces the dorsal support of the SLIL has generated research into using bone–tissue– bone (BTB) composite grafts.27,30,31,34,41,48 –50 A large body of research is centered on the design use of other tendon grafts in orthopedic surgery, such as the anterior cruciate ligament. The success of a BTB graft in the replacement of this high-demand ligament probably sparked an interest in grafts for the SLIL. Tarsometatarsal joint autograft,27,41 SLIL allograft,5,12 capitohamate ligament composite,42 metacarpal– carpal composite,49 and bone–retinaculum– bone autograft harvested from the dorsal radius30 all have been examined. The biomechanical goal has been a replacement graft with a strength and stiffness approaching that of the SLIL. All of these procedures currently are investigational; however, early to medium-length follow-up reports of these techniques all have been favorable, and one or more BTB grafts undoubtedly will play a part in the future management of SLIL repair.
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straints to differential rotation between the scaphoid and the lunate. The greatest yield strength was found in the dorsal region (260.3 ⫾ 118.1 N), followed by the palmar region (117.9 ⫾ 21.3 N) and the proximal region (62.7 ⫾ 32.2 N). Similar results in other studies44,45 have led to the conclusion that the dorsal portion of the scapholunate ligament is the most important for carpal stability and therefore the best physiologic target for corrective surgery. Technically, this also is appealing because of the easier dorsal approach used to perform the repair. These biomechanical studies also provided other investigators with the ideal strength to aim for in the design of a replacement BTB graft.
Remote Bone–Tissue–Bone Grafts It is only recently that BTB grafts have been used for scapholunate dissociation. Svoboda et al27 reported the biomechanical properties of foot autografts in 1996. The SLIL and 3 cadaveric autograft candidates from the foot were harvested as BTB complexes. Servohydraulic testing until failure compared their stiffness and strength values. Analysis indicated that the stiffness values for the tarsometatarsal ligament and the SLIL were statistically similar; however, the strength values of all 3 autografts from the foot were significantly less than those of the SLIL. Davis et al41 examined an alternate BTB from the foot that more closely approached the characteristics of the SLIL. Although their graft (the dorsal–medial portion of the navicular–first cuneiform ligament) was weaker than the SLIL, they believed it was a good clinical option and continue to perform this surgery. They perform the graft harvest through a 4-cm medial incision with fluoroscopic control. The tibialis anterior is released
The Scapholunate Interval Although the integrity of the scapholunate ligament may not be the only determinant of the scapholunate angle and the resultant arthritic changes of the wrist, it certainly is the most obvious constraint to the scapholunate interval. Several studies have looked at the relative importance of various portions of the scapholunate ligament. Berger et al42,51 studied the material and constraint properties of the dorsal, proximal, and palmar regions of the scapholunate ligament. Determinations of constraint to differential rotation and translation as well as failure strength were made. The dorsal region of the scapholunate ligament offered the greatest constraint to differential translation, whereas both the dorsal and palmar regions showed statistically significant combined con-
Figure 1. Approach for the harvest of the foot-based BTB graft. The navicular-cuneiform site has been shown to be the graft most biomechanically similar to the SLIL (T.A., tibialis anterior; M.M., medial malleolus).
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Figure 2. Bone–retinaculum– bone graft showing the necessary steps in surgery. (A) A large irreparable scapholunate gap (large white arrow) was visualized at the time of surgery in a 49-year-old man. (B) Trough fashioned in the scaphoid (black arrow) and the lunate (white arrow) after the scapholunate interval was reduced anatomically and held in place with K-wire fixation. The K-wires are in the volar portion of the 2 bones to prevent protrusion in the trough. (C) The BTB graft from the dorsal retinaculum was placed in the trough and held in place with 2 small screws. (D) Sufficient K-wire fixation has been placed to maintain the scapholunate angle and the interval on lateral and anteroposterior fluoroscopy. The 2 internal fixation screws are seen well placed within the lunate and the scaphoid. (E) At the 2-year follow-up evaluation the interval has been well maintained without increased arthrosis.
and retracted posteriorly for best access (Fig. 1). They attempt to harvest a graft that is 10 ⫻ 5 ⫻ 5 mm on each side of the joint. The graft is secured in the manner popularized by Weiss31 (Fig. 2). Osterman and Culp have treated 49 patients with the SLIL graft, with an average follow-up period of 2 years (A. Osterman, personal communication, June 2006). They have had several cases of tissue stretching during healing without loss of angulation. In their subgroup of patients with static SLIL, only 1 patient has had graft failure, patients have obtained 80% of motion, and have increased their grip strength by 30%. Of note, they based their treatment options for
a SLIL injury as per Garcia-Elias et al,52 in which complete tears that were irreparable, nonarthritic, dynamic, reducible, and greater than 4 mm usually were treated with a BTB graft (⫾ a temporary bridging screw). Although morbidity of the secondary foot incision has not been reported widely, several investigators34,36,50 have reflected on the dangers of surgery on an otherwise healthy lower extremity. More recently, researchers have reported on other sites used that are remote from the hand. A BTB harvested from the iliac crest has been compared biomechanically with the dorsal SL ligament and believed to be statistically similar.17 Despite several reports on the
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morbidity of an iliac crest bone graft harvest in the literature, perhaps the nature of a BTB graft would minimize these complications.
Isolated Dorsal Retinaculum Grafts Weiss30 first described a BTB from the dorsum of the hand that was harvested near Lister’s tubercle (third extensor compartment base) on the distal radius. Harvesting of the extensor retinaculum and bone block allowed the fashioning of a bone–retinaculum– bone composite graft that was used to reconstruct the dorsal portion of the SLIL. Bone plugs of the graft were fitted into the dorsal scaphoid and the lunate with a retinaculum–periosteal soft-tissue sleeve arching between these 2 bones.31,53 Figure 2 shows the basic surgical technique used in all BTB surgeries. A 49-year-old man with a complete SL tear (Fig. 2A) complained of pain with any loading activity. Intraoperative photographs showed the trough fashioned in the reduced scaphoid and lunate (Fig. 2B) and the graft held in place with 2 small screws (Fig. 2C). Fluoroscopy from the time of surgery showed good reduction of the scapholunate interval (Fig. 2D). At the 2-year follow-up evaluation the patient had no pain with equal grip strength (extension/flexion, 65/50 ft-lb; radial deviation/ulnar deviation, 15/30 ft-lb). Follow-up radiographs from that time (Fig. 2E) showed maintenance of the scapholunate interval. This technique was evaluated over a short-term follow-up evaluation in 19 patients (mainly with dynamic instability). The SLIL was reduced and pinned for 8 weeks with cast immobilization. In the initial clinical series by Weiss,31 14 patients were treated with this technique. The follow-up period averaged 3.6 years. In general, the range of motion decreased slightly from the preoperative values, but grip strength improved and patients were satisfied with the procedure. A second study25 reported on the biomechanical testing of this reconstruction. The BTB and dorsal SLIL specimens were harvested from 6 fresh-frozen human cadaveric forearms. The BTB autograft was significantly weaker than the SLIL. The investigators believed that because the mean cross-sectional area of the dorsal SLIL was more than 3 times as large as that of the BTB autograft, the failure stress (failure force/crosssectional area) of the BTB autograft was not markedly different from that of the dorsal scapholunate ligament. They believed that the BTB autograft was appropriate graft material for scapholunate ligament reconstruction, but that structural parity with the dorsal SLIL ultimately will depend on remodeling and
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hypertrophy during healing. Other investigators54 have looked at the viability of retinacular grafts from the distal radius. An overview of the anatomy of the extensor retinaculum, with radiographic and morphometric measurements, was accomplished.55 Ten cadaver wrists were dissected and the thick portion of the retinaculum and its insertions on the radius in the different extensor compartments were studied. A comparison of dissections with radiographs showed that the radial compartments 1, 2, and 3 were suitable for bone–ligament– bone grafting. The mean compartment length was 11.7 mm for compartment 1, 17 mm for compartment 2, and 7.3 mm for compartment 3. This leaves several options in the distal radius for a BTB graft harvest.
Metacarpal-Carpal–Based Bone–Tissue–Bone Grafts Other investigators began to look at options based within the hand itself that might have better biomechanical characteristics to replace the SLIL. The carpometacarpal bone–ligament– bone complex at the base of the second or third metacarpal was proposed as a replacement for the SLIL.49 These articulations are relatively immobile and therefore were seen as expendable if needed for SLIL reconstruction. Both of these grafts also were obtainable easily through the same dissection used for the SLIL repair. These grafts also provide a cartilaginous replacement for the SLIL interval on both the scaphoid and lunate surfaces. Harvey and Hanel49 performed a biomechanical study of cadaveric-matched SLILs, second metacarpal–trapezoid ligaments, third metacarpal– capitate ligaments, and the dorsal retinaculums. Stiffness and strength were obtained from fresh-frozen specimens tested to failure with a servohydraulic apparatus as performed in previous studies. The second metacarpal–trapezoid ligament and the third metacarpal– capitate ligament most closely approximated the stiffness and strength of the SLIL. The dorsal periosteal retinaculum was significantly less stiff and weaker than the SLIL. These 2 new grafts were seen as desirable graft replacements. Another group of researchers substantiated these findings. The mechanical properties of 2 intracarpal ligaments were compared with those of the dorsal component of the SLIL. Trapezoid–to–second metacarpal and capitate–to–trapezoid ligaments and the dorsal part of the SLIL were obtained as bone–ligament– bone grafts from fresh-frozen cadavers. Servohydraulic testing showed that the capitate–to–trapezoid ligament closely approximated the load to failure and
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and protected as it is traced back to the radial artery (Fig. 4B, C). The dorsal intercarpal ligament is incised and repaired during the procedure. The origin of the artery is dissected back to the radial artery proper, freeing sufficient length origin from the radial artery is freed and the resultant to allow placement of the graft in the trough fashioned on the scaphoid and lunate as per Weiss31 (Fig. 4D). The graft is protected by pinning for 8 weeks, and this is followed up by careful mobilization and return to all activities by 3 months. Figure 3. Radiographs 1 year after SLIL repair with a third metacarpal– carpal autograft. The revascularization phase of healing has resulted in a weakened SLIL and the outcome is a stretched ligamentous graft. Figure courtesy of Dr. G. M. Elder.
stiffness of the dorsal SLIL, whereas the trapezoid– to–second metacarpal ligament was significantly stronger and stiffer than the dorsal SLIL. The investigators believed that these 2 grafts were viable options to replace the dorsal SLIL. A small clinical series with short-term follow-up evaluation has shown the third metacarpal– carpal BTB to be successful.50 This technique has been published and is similar to the technique used by Weiss31 for a dorsal retinacular graft. Personal experience with 25 of these surgeries has shown only a limited number of complications. In general the clinical outcome is good and has been successful in the hands of several surgeons. The 2 main complications are graft pullout, usually from the lunate, and graft stretching, with an increased scapholunate interval but no loss of the scapholunate angle (Fig. 3). Graft pullout occurs from a lack of healing in the patchy vascularized lunate and typically is seen in chronic dissociations or lunate dislocations. Lack of healing eventually results in bone or hardware failure. Stretching of the SLIL replacement occurs after several months, with loss of the tight SLIL interval. Presumably this is caused by the revascularization phase of healing, causing graft weakness.
Vascularized Metacarpal-Carpal–Based Bone–Tissue–Bone Grafts In an attempt to prevent these 2 observed complications a vascularized BTB has been designed and is currently in use. A typical third metacarpal– carpal graft can be harvested based on the radial-sided intermetacarpal artery (Fig. 4A). This artery is lifted
Carpal-Based Bone–Tissue–Bone Grafts After their work with scapholunate biomechanics, Ritt et al55 looked at hand-based BTB options for SLIL replacement. In particular they believed that the capitohamate joint would provide an adequate ligament. The study of the capitohamate joint revealed 3 interosseous ligaments: the dorsal, deep, and palmar interosseous ligaments. Their physical attributes were tested in a computer-controlled multiaxis testing machine. In the intact joint complex, the average dorsopalmar rotational displacement was approximately 9° in each direction. Based on sequential sectioning it was found that the dorsal ligament provided 76% of the rotational resistance with palmar rotation of the capitate and 44% of the translational constraint with palmar translation of the capitate. The deep ligament provided 51% of the rotational resistance with dorsal rotation of the capitate and 63% of the translational resistance with dorsal translation of the capitate. With proximal-distal translation, the dorsal ligament was the most important constraint in each direction. In resisting distraction, each of the 3 ligaments was equally effective. Failure testing showed that the deep ligament was strongest at 289 N, followed by the palmar ligament at 171 N, and the dorsal ligament at 133 N. They have progressed to clinical implementation with the harvest of the dorsal capitohamate joint (excluding the deep and palmar ligaments) as a BTB graft (Fig. 5).56 The BTB is supplemented by a capsulodesis. The patients have protected motion beginning at 4 weeks until pin removal at 8 weeks. Strengthening starts at 3 months and athletes are allowed to return to full activity by 20 weeks. Clinical results have been promising but have yet to be published. Berger performs the BTB graft only if (1) any angular carpal malalignments are reduced easily, (2) there is no degenerative joint disease, and (3) the lunate is not translated ulnarly more than 50% off of the lunate fossa (R. Berger, personal communication, June 2006).
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Figure 4. Vascularized BTB graft from the hand. Based on the intermetacarpal and radial arteries the graft is harvested with a pedicle of sufficient length to allow translation to the trough fashioned in the scaphoid and the lunate. (A) Dorsal approach to harvest the vascularized third metacarpal– carpal BTB. The thin arrow shows the consistent branch of the intermetacarpal artery. This can be traced with careful dissection to the terminal dorsal branch of the radial artery. The large black arrowheads point to K-wires placed on both the radial and ulnar sides of the wrist. The K-wires must be placed volar to avoid protrusion into the fashioned trough in the scaphoid and lunate, but also to avoid injury to the branches of the radial artery. (B) Intraoperative fluoroscopy showing closure of the scapholunate interval with several K-wires. The smaller K-wires delineate the graft harvest site at the third metacarpal– capitate interval. Three K-wires are used at the limits of the harvest site (C) to delineate the resection margins for safety. The fourth corner of the graft has no K-wire placed because this is the region of artery insertion (radial capitometacarpal joint). (C) Superimposed graphics represent important landmarks. The square is the harvest site for the BTB that is based on the intermetacarpal artery system (multiple white arrows). (D) The graft has been harvested (large black arrowhead) and translated proximally to the trough in the scaphoid and the lunate. The white arrows show the ulnar and radial placement of the K-wire fixation for safety of the radial artery. The small white arrowheads trace the vascular pedicle and graft in place within the trough.
Augmented Dorsal Retinaculum Grafts In 1991, Herbert56 first reported the concept of an augmented repair using a Herbert screw (Zimmer Inc, Warsaw, IN). The surgical technique involved open reduction and re-attachment of the ligament to the bone, combined with Herbert screw fixation across the scapholunate joint. The screw was left in situ for 12 to 18 months, allowing sufficient time for ligament healing and restoration of carpal stability. He believed this technique allowed early postoperative wrist motion. Excellent results were achieved in the majority of patients but a subgroup of patients showed increasing carpal collapse deformity. Primary repair has such varied results57 that the failures may have been caused by inherent deficiencies in the
Figure 5. The black arrow shows the capitohamate intercarpal ligaments that are retained as a BTB from a dorsal exposure. Only the dorsal ligament composite is taken, which does not destabilize the carpal relationship.
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Figure 6. Herbert screw augmentation of the BTB graft. (A) After reduction of the widened interval through a dorsal approach the Herbert screw drill is placed percutaneously from the radial side through the scaphoid into the center of the lunate (LUN). The drill must be parallel to the radius joint at the scapholunate ligament. (B) Immediate postoperative view of the repair with 2 small screws holding the BTB in place and the larger Herbert screw spanning the 2 bones. (C) After 1 year the spanning screw has been removed. The lunate screw also has been removed. The interval has been maintained. (D) The lateral view at 1 year also shows maintenance of the scapholunate angle.
primary repair technique. Other surgeons have started to use this Herbert screw technique with a BTB graft for the restoration of ligament continuity. Fernandez has had preliminary clinical experience with this technique (D. Fernandez, personal communication, June 2006). He used the BTB graft used by Weiss30 plus a Herbert screw to treat a small group of patients. Initial reduction of the scapholunate interval is performed with a sharp towel clamp through a dorsal approach. Herbert screw fixation is performed
percutaneously from the radial side. It is important to ensure that the screw is parallel to the distal radius in the anteroposterior view to ensure appropriate flexion without screw loosening and anatomic scapholunate articulation (Fig. 6A). The BTB grafting then is performed in the normal fashion (Fig. 6B). K-wire immobilization is not used. The Herbert screw is removed at 9 months to 1 year (Fig. 6C, D). Fernandez had 80% of his first 20 patients return to their previous working levels when he used Herbert screw
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augmentation (D. Fernandez, personal communication, June 2006). One patient had pullout of the screw and stretching of the ligament, and another patient was left with a fixed dorsal intercalated segment instability deformity. There are several options to repair a SLIL insufficiency. The options discussed in this article encompass the newest approaches to the problem. Unquestionably, the early results for these procedures are excellent compared with other historical options; however, no randomized control groups have been established. The procedures are not technically beyond the scope of all hand surgeons, and except for the vascularized option, are not beyond the capabilities of any orthopedic surgeon. Other surgeons have stated that the reason that these procedures function is because of an arthrodesis between the scaphoid and lunate and that long-term outcomes will be poor. It is unlikely that fusion is the mode of success for these procedures. It is obvious from radiographic studies that there is a clear space between the 2 bones. Also, in a fluoroscopic study performed at our institution, the scaphoid and lunate continued to move in relation to each other. The BTB repair, in whatever form the surgeon chooses, is a good option for scapholunate repair and will be part of the future armamentarium of all hand surgeons. Received for publication July 18, 2006; accepted in revised form November 20, 2006. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Edward J. Harvey, MD, Chief of Hand and Microvascular Surgery, Division of Orthopaedic Surgery, McGill University Health Centre—Montreal General Site, 1650 Cedar Ave, Room B5.159.5, Montreal, Quebec, Canada H3G1A4; e-mail: Edward.harvey@ much.mcgill.ca. Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A02-0019$32.00/0 doi:10.1016/j.jhsa.2006.11.011
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