LUNOTRIQUETRAL INJURIES

BY WARREN L. BUTTERFIELD, MD, ATUL B. JOSHI, MD, AND DAVID LICHTMAN, MD

Lunotriquetral injury is an important consideration in the evaluation of ulnar- sided wrist pain. An understanding of the anatomy, kinematics, and pathome- chanics of this injury assists in elucidating the diagnosis through history and physical examination. The use of appropriate radiographic imaging may provide additional support for the diagnosis. Arthroscopy has emerged as not only the gold standard for diagnosis of this injury, but also as an effective means of treatment. Treatment decisions must be based on both the degree of severity and acuity of the injury. Although the majority of patients will do well with nonoperative management, the indications for surgery and the varied outcomes of surgical management are discussed. Copyright © 2002 by the American Society for Surgery of the Hand

arpal instabilities result from a spectrum of pathomechanics, clinical presentation, and manage- injuries involving both osseous and ligamen- ment of lunotriquetral injuries. tous structures. Early literature on carpal in- C ERMINOLOGY stabilities focused on the scaphoid and the radial side T of the wrist; however, as advances in technology and surgical techniques have developed and a better un- arpal instabilities have been classified as static derstanding of wrist biomechanics has become avail- C(visible deformity on radiographs), dynamic (vis- able, there has been an increased understanding of ible deformity on stress radiographs or fluoroscopic ulnar carpal instabilities. stress tests), or predynamic (ligamentous injury with- As a group, ulnar carpal injuries are about one-sixth out radiographic deformity). In the case of lunotrique- as common as their radial counterparts.1 They are tral injuries, the term dissociation has been used clin- categorized into triquetrohamate, or midcarpal, insta- ically to describe static instability and the term sprain bility and lunotriquetral instability. Lunotriquetral has been used clinically to describe predynamic and injury is an unusual cause of ulnar-sided wrist pain. It dynamic instabilities.2 To avoid confusion, we often results from both traumatic and degenerative etiolo- refer to these injuries as unstable (equivalent of static), gies. This article discusses the anatomy, kinematics, dynamically unstable (equivalent of dynamic), and stable (equivalent of predynamic). We have titled the article as lunotriquetral injuries rather than instabilities to From the Department of Orthopedics, JPS Health Network, Fort emphasize that not all injuries are unstable. Worth, TX. Address reprint requests to Warren L. Butterfield, MD, Department of Orthopedics, JPS Health Network, 1500 S. Main St, Fort Worth, WRIST ANATOMY AND KINEMATICS TX. o achieve a functional range of motion and yet Copyright © 2002 by the American Society for Surgery of the Hand 1531-0914/02/0204-0006$35.00/0 Tstill maintain stability, the wrist requires a com- doi:10.1053/jssh.2002.36790 plex articular configuration that does not readily lend

JOURNAL OF THE AMERICAN SOCIETY FOR SURGERY OF THE HAND ⅐ VOL. 2, NO. 4, NOVEMBER 2002 195 196 LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL

mal, and dorsal surfaces of the bones, leaving the distal aspect of the joint in open communication with the midcarpal joint.3 The 3 regions are distinct.4 The dorsal and palmar interosseous ligaments are true ligaments, but the proximal ligament is actually a fibrocartilaginous membrane and provides little sta- bility. The palmar ligament is the thickest and stron- gest, and it is the most important in resisting palmar translation. The dorsal ligament is the most important for rotational resistance. They are equally responsible for resisting dorsal translation. The scaphotriquetral ligament passes along the distal margins of the dorsal surfaces of the scaphoid, lunate, and triquetrum and is considered a distal extension of the interosseous liga- ments.3 The proximal carpal row moves passively in re- sponse to compressive and tensile forces generated by bony structures and soft-tissue constraints. In the normally constrained wrist, the reactive forces across the midcarpal joint are balanced. In flexion and ex- tension, the proximal carpal row moves in synchrony with the distal carpal row and the metacarpals5; how- FIGURE 1. Palmar ligaments. ever, with ulnar and radial deviation, the dynamics become more complex. With radial deviation, com- pressive forces across the scaphoid-trapezoid-trape- itself to anatomic description and interpretation. In addition to guiding motion of the hand in space, the many intercarpal linkages serve as shock absorbers to diffuse and redirect force transmitted from the hand to the forearm. Aside from the insertion of the flexor carpi ulnaris on the pisiform and hook of the hamate, the carpal bones have no tendinous insertion; there- fore, these functions depend mostly on bony structures and soft-tissue constraints. The ligamentous anatomy of the wrist has been well described.3 Most of the ligaments are thickenings of the joint capsule with longitudinally oriented groups of collagen fibers. They are categorized as extrinsic (insertions on both the carpal bones and on structures external to the carpal bones) and intrinsic (insertions exclusively within the carpal bones). These ligaments are further divided into dorsal and palmar groups. The ligaments pertinent to our discussion are shown in Figures 1, 2, and 3. The intrinsic ligaments, interosseous and scapho- triquetral (Fig 3), tightly constrain the proximal row. The interosseous ligament covers the palmar, proxi- FIGURE 2. Dorsal ligaments. LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL 197

PATHOMECHANICS

ultiple cadaveric studies have helped to eluci- Mdate the mechanisms of lunotriquetral injury and to identify relevant anatomic structures. In 1980, Mayfiled et al7 presented a classic study on perilunate instability. They showed that loading in maximal extension, ulnar deviation, and intercarpal supination causes progressive injury (Fig 4). They defined a lesser arc, purely ligamentous, and a greater arc, involving carpal bones, around which injury progresses. This may produce combinations of bone and ligament in- juries. Note that via this mechanism, lunotriquetral injury does not occur until stage III, and would thus have multiple associated injuries. Pin et al8 showed in cadavers that carpal ligament injury forms a spectrum: from elastic elongation to permanent elongation to tear. He showed that extrin- sic ligaments have more capacity for stretch than intrinsics, such that the intrinsic ligaments can be completely disrupted whereas the extrinsic ligaments are only partially injured. He suggested this as the mechanism of the forme fruste injury (lunotriquetral FIGURE 3. Interosseous ligaments. instability as the only clinical manifestation of stage III perilunate injury) proposed by Lichtman et al.9 zium (STT) complex cause the distal pole of the Reagan et al2 described isolated lunotriquetral scaphoid to flex. The lunate and triquetrum follow sprains after wrist trauma. They suggested that hy- passively into flexion, and are forced to translate dor- pothenar loading from a fall on an outstretched hand sally and pronate as the triquetrum interacts with the in maximal extension and radial deviation would re- hamate. With ulnar deviation, the triquetrum en- sult in the reverse order of injury proposed by May- gages the hamate’s helical articular surface. As the filed et al.7 The first stage of this mechanism allows for hamate moves ulnarward, local joint reactive forces isolated lunotriquetral sprain. This group also classi- cause the triquetrum to extend while moving pal- fied lunotriquetral injuries, based on the integrity of marly down the helicoid track of the joint.5 This the interosseous ligaments, into the broad categories results in extension and palmar translation of the of sprains and dissociations. entire proximal row. Alexander and Lichtman10 have postulated that Horii et al5 showed that motion between the lunate isolated lunotriquetral injuries also may occur with and the triquetrum during flexion or extension was similar to motion between the 2 bones during radial the wrist palmar flexed. A dorsally applied force then or ulnar deviation. A clinical study has revealed that causes the interosseous fibers to fail but spares the complete synostosis of the lunate and triquetrum re- palmar radiolunotriquetral ligament. 11 sults in asymptomatic wrist function.6 These 2 points Palmer and Werner identified that ulnar positive support the concept that normal wrist mobility and variance causes increased ulnar loading and degener- stability require an intact lunotriquetral interosseous ative injuries on the ulnar side of the wrist. It is ligament that fixes both bones into a single mechan- conceivable that not only does ulnar positive variance ical unit and determines the position of the lunate result in degenerative changes, but also predisposes to throughout wrist range of motion. lunotriquetral injury with axial loading. 198 LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL

dynamic instability,12 but has been observed to allow slightly abnormal intercarpal motions.5,13 Additional sectioning of the palmar lunotriquetral ligaments re- sulted in dynamic volar intercalated segment instabil- ity (VISI),12,13 thus these ligaments were determined to be important for proper rotation of the carpal bones on radial or ulnar deviation. Still further sectioning of the dorsal radiocarpal ligaments (dorsal radiotrique- tral and dorsal scaphotriquetral) resulted in static VISI.5,12,13 In applying the ring concept of carpal kinematics, Lichtman10 postulated that there is a potential flexion moment at the STT link and an extension moment at the triquetrohamate link, and that these moments are balanced in the intact wrist. With a break at the lunotriquetral joint, compressive forces at the STT cause the scaphoid to flex. Simultaneously, the head of the capitate moves proximally into the lunotriquetral gap and causes the triquetrum to move ulnarward on the hamate, effectively creating an extension thrust on the triquetrum via movement on the helical slope. Because the lunate is still attached to the scaphoid, it will follow the scaphoid into flexion and create a VISI deformity. The extent of the deformity often correlates with the extent of ligament damage. In summary, the stability of the carpal complex is derived from a combination of precisely opposed, mul- tifaceted articular surfaces with both intrinsic and extrinsic ligamentous restraints. Damage to the in- terosseous ligaments results in micromotion instabil- ity that can cause synovitis or arthritis; however, interosseous ligament rupture is not sufficient to allow VISI because the extrinsic ligaments (dorsal radiocar- pal and palmar carpal ligaments) provide important secondary restraints. With damage to these secondary constraints, the opposing moments on the proximal row cause unbalanced movement into the predictable pattern of VISI. This imbalance will be manifested by either dynamic or static instability depending on the extent of ligamentous damage.

LINICAL RESENTATION AND XAMINATION FIGURE 4. (A) Perilunate injury. (B) Four stages of progres- C P E sive perilunar instability. he history and physical examination are impor- Cadaver studies also have identified the ligaments Ttant elements in correctly identifying lunotrique- that are important for lunotriquetral stability. Sec- tral injury. The typical patient will give a history of a tioning of the lunotriquetral interosseous ligaments specific injury, usually a fall on an outstretched hand; does not result in radiographically detectable static or however, twisting, pulling, pushing, catching, and LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL 199

a dorsal force to the pisiform/triquetrum and his other TABLE 1 thumb to apply a volar force to the lunate. Laxity Differential Diagnosis of Ulnar-Sided Wrist Pain compared with the other hand or reproduction of the Entrapment of the dorsal branch of the ulnar nerve patient’s symptoms is considered positive. A click Triangular fibrocartilage tear with neutral to ulnar deviation with the wrist prona- Ulnocarpal arthrosis Midcarpal instability ted and under axial compression has been reported to Kienbock’s disease be a predictable finding in patients with dynamic Extensor carpi ulnaris subluxation lunotriquetral injury.5 Injection of the midcarpal joint Extensor carpi ulnaris or flexor carpi ulnaris tendonitis 10 Distal radioulnar joint subluxation with local anesthetic can be a useful diagnostic tool. Pisotriquetral arthrosis Resolution of pain and increased grip strength after Fracture of the hook of the hamate, ulnar styloid, or injection are sensitive, but not specific, indicators of triquetrum Ulnocarpal impingement lunotriquetral injury. Chondromalacia of lunate or distal ulna Lunotriquetral synostosis Lunotriquetral injuries RADIOGRAPHIC STUDIES

tandard posteroanterior and lateral radiographs of Sboth wrists in neutral rotation allow for measure- striking also have been reported as inciting events.2 ment of static carpal alignment16 and for assessment of There is a high incidence of associated carpal bone, ulnar variance.17 The posteroanterior view should be carpal ligament, and triangular fibrocartilage complex inspected for carpal integrity and for the smooth arcs injuries.14 that are formed by the proximal and distal joint Patients often present several weeks, or even surfaces of the proximal carpal row (Gilula’s arcs 1 and months, after the acute injury. Ulnar-sided wrist pain 2) and the proximal joint surface of the capitate and is a common chief complaint. The patients often hamate (Gilula’s arc 3) (Fig 5). Disruption of these describe their pain as persistent with increased inten- arcs indicates ligament damage allowing subluxation sity after heavy use. Patients may provide additional or dislocation. Overlapping of normally parallel artic- history of clicking with ulnar deviation, grip weak- ular surfaces is also an indicator of ligament damage. ness, and/or a sense of wrist instability.10 The lateral view should be evaluated for interca- Physical examination should involve the entire lated collapse deformities. The most direct method of wrist and hand to rule out other causes of ulnar-sided wrist pain (Table 1). Unless the injury has occurred quite recently, there likely will be no swelling. The wrist may have some limitation of motion, and there is nearly always tenderness over the lunotriquetral joint. There are several diagnostic adjuvants that aid in correctly identifying lunotriquetral pathology. The ulnar snuffbox test15 is performed by applying lateral pressure to the triquetrum between the flexor carpi ulnaris and the extensor carpi ulnaris tendons. Pain is considered a positive test result. The ballottement test2 is performed by grasping the triquetrum and pisiform between the thumb and index finger of one hand and the lunate between the thumb and index finger of the other. The triquetrum is then rocked back and forth on the stabilized lunate. Again, pain is considered a positive test result. The shear test15 is performed by the examiner using one thumb to apply FIGURE 5. Gilula’s lines. 200 LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL

doing this is to compare the longitudinal axis of the and soft-tissue lesions that may mimic symptoms of lunate with the longitudinal axis of the capitate and lunotriquetral injury (eg, Kienbock’s disease, ulnar radius. They should be reasonably collinear. Another abutment syndrome).10 As newer imaging techniques method2 involves determining the longitudinal axis of emerge, and advances in technology improve resolu- the triquetrum and the longitudinal axis of the lunate. tion, MRI may play an increasingly valuable role as a The longitudinal axis of the triquetrum is defined as a diagnostic tool in the future. line passing through the distal triquetral angle and Other useful imaging techniques have been pro- bisecting the proximal articular surface. The longitu- posed.16 Movements that recreate the patient’s symp- dinal axis of the lunate is defined as a line bisecting toms viewed under fluoroscopy may reveal dynamic the distal and proximal surfaces of the lunate at right instability. A bone scan may be used to identify the angles to a line across the palmar and dorsal distal presence or absence of inflammation if patient malin- poles. The average normal lunotriquetral angle mea- gering is suspected. sures positive 14° (range, Ϫ3° to 31°), and the aver- age angle in wrists with lunotriquetral dissociation is ARTHROSCOPY Ϫ16° (range, Ϫ50° to Ϫ3°). The radiographic appearance of wrists with isolated rthroscopy22 is the most definitive modality for intrinsic ligament tears are typically normal; however, Athe evaluation of lunotriquetral injuries and has posteroanterior clenched fist (stress) views and pos- become the gold standard for diagnosis. It allows for teroanterior views in ulnar and radial deviation may definitive treatment of many soft-tissue injuries and reveal dynamic instability.16 Because Gilula’s lines are permits evaluation of ligament tears before undertak- not accurate indicators of lunotriquetral instability in ing open surgical treatment. This provides better radial or ulnar deviation views, comparison with the preoperative planning and facilitates an informed dis- other side must be performed to detect abnormalities cussion regarding treatment options with the patient. accurately. A systematic examination of the wrist is performed Arthrography14,18 has been used extensively in di- to identify all injuries. The degree of instability be- agnosing lunotriquetral injuries. Leakage of dye from tween the lunate and triquetrum can only be assessed the midcarpal joint into the radiocarpal joint or vice by evaluating both the midcarpal and radiocarpal versa is considered a positive test. The triple injection joints. Examination of the radiocarpal joint allows arthrogram in combination with cinearthrography in- assessment of the synovium, the proximal carpal ar- creases sensitivity and specificity; however, the proce- ticular surface, the radial and ulnar articular surfaces, dure is time consuming and has a high incidence of the scapholunate interval, the volar radiocarpal liga- false positives owing to increased numbers of asymp- ments, the lunotriquetral interosseous ligament, and tomatic degenerative perforations that develop with the triangular fibrocartilage complex. Because the in- increasing age. In light of the advantages of arthros- terosseous ligament does not extend distally, exami- copy in the diagnosis and management of these inju- nation of the midcarpal joint allows a good look into ries,18 we do not routinely use arthrography in the the lunotriquetral interval. Injuries can be classified work-up of these lesions. based on the integrity of the interosseous membrane A recent study19 showed that computed tomogra- as observed from the radiocarpal space and the con- phy of the wrist after dye injection of the radiocarpal gruity of the joint surface from both the midcarpal and midcarpal joints has similar sensitivity and spec- and the radiocarpal space (Table 2).23 ificity as compared with arthrography in the diagnosis of carpal ligament injuries. This modality has the TREATMENT added advantage of identifying the precise location of the lesion. We do not have experience with this everal factors must be considered when deciding technique. Son the optimal treatment plan for a patient. De- Although magnetic resonance imaging (MRI) has gree of stability, time elapsed since injury, associated not reliably diagnosed lunotriquetral ligament tears in injuries, ulnar positive variance, and demands of the published studies,20,21 it allows visualization of bone patient will all affect treatment choice. LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL 201

zation; however, if the injury is chronic, this is less TABLE 2 likely to be curative. A large portion of patients Geissler Classification with dynamically unstable injuries will obtain re- Attenuation or hemorrhage of interosseous ligament as lief of symptoms after shaver debridement25; how- viewed from the radiocarpal joint ever, one study1 revealed poor results with debride- No incongruency of carpal alignment as viewed from the midcarpal space ment alone. Therefore, recent investigators have Attenuation or hemorrhage of interosseous ligament as recommended that arthroscopic reduction and pin- viewed from the radiocarpal joint ning also be performed.27 The heads of the pins are Step-off of carpal alignment as viewed from the midcarpal space, probe is unable to pass into the buried subcutaneously and the wrist is splinted for gap 8 weeks. This provides very good results in most of Incongruency or step-off of carpal alignment as seen from bothradiocarpal and midcarpal spaces, these patients. probe may be passed between carpal bones For unstable lesions, as well as dynamically un- Incongruency or step-off of carpal alignment as seen stable lesions not amenable to arthroscopic treat- from bothradiocarpal and midcarpal spaces, gross instability withmanipulation, 2.7-mm ment, open surgical repair is indicated. The goals arthroscope may be passed through the gap of surgical intervention are the realignment of between the bones the lunocapitate axis, the reestablishment of the rotational integrity of the proximal row, and the reduction of excessive intercarpal motion. Direct ligament repair, ligament reconstruction, and arth- Initial treatment of stable injuries, both acute and rodesis all have been proposed as open surgical chronic, consists of immobilization. Either a carefully methods for the unstable injury. molded cast with a supporting pad under the pisiform Direct ligament repair2 is most appropriate in the or a wrist splint with a lateral supracondylar extension acute setting, before the torn ends of the ligament to prevent pronation24 will help to maintain optimal atrophy. Multiple strand repair using bone tunnels or alignment as ligament healing progresses and inflam- suture anchor implants is required in addition to mation subsides. Nonsteroidal anti-inflammatory K-wire fixation. The repair is protected for at least 6 medications and cortisone injections also may be nec- weeks, but may be continued longer if pain persists. essary, especially in injuries that present more than 3 The aim of repair is to restore carpal kinematics. to 4 weeks after the inciting event. The injury may 13 require 3 to 6 months of treatment for complete Although Ritt et al showed in cadavers that liga- resolution of symptoms.24 This will be curative in the ment repair does not reproduce normal carpal kine- 2,28 majority of patients; however, if symptoms do not matics, clinical results suggest that the procedure significantly improve within 6 weeks, arthroscopy is effectively relieves symptoms. Primary ligament re- warranted to further assess the injury and allow for pair is less efficacious when performed after the acute definitive treatment.25,26 inflammatory response or when performed in patients Arthroscopy allows direct visualization and re- demanding high use.28 pair of articular pathology. In stable injuries, the In patients with chronic injuries, ligament recon- fibrocartilaginous portion of the interosseous mem- struction should be weighed against lunotriquetral brane is often the only lunotriquetral structure fusion. Reconstruction is performed by using the ra- damaged. This portion of the interosseous mem- dial half of the extensor carpi ulnaris tendon, leaving brane heals poorly and is associated with ulnar- its distal attachment intact.15 The ligament is passed sided synovitis. Simple motorized shaver debride- through bone tunnels in the lunate and triquetrum to ment provides symptomatic relief in the majority of form a loop. The dorsal radiocarpal ligament is ad- patients.25,26 It is important to debride only the vanced and tacked onto the repair. K-wires are used to fibrocartilaginous portion of the ligament to avoid stabilize the repair, and it is protected for at least 6 producing iatrogenic instability. weeks. The argument in favor of reconstruction is that Dynamically unstable injuries, whether acute or it restores normal kinematics; however, the surgery is chronic, may be managed initially with immobili- technically demanding and has a high learning curve. 202 LUNOTRIQUETRAL INJURIES ⅐ BUTTERFIELD ET AL

Additionally, it is supported by only one published CONCLUSION outcome study at the present time.28 Our own experience has been that arthrodesis is a unotriquetral injury is an unusual cause of wrist reliable option if the lunotriquetral joint is adequately Lpain, but must be considered in the work-up of decorticated, autogenous bone graft is used, the cor- pain on the ulnar side. The pathomechanics of the rect anatomic relationships of the various carpal bones injury have been described and standard clinical and are maintained, and ulnar abutment, if present, is radiographic patterns have emerged. As with other properly addressed. Lunotriquetral fusion has been carpal instabilities, these injuries may be stable, dy- used widely with results varying from fair to excel- namically unstable, or unstable. The diagnosis usually lent.29-34 A recent series by Guidera et al29 showed a can be made on the basis of a good history and 100% fusion rate with 83% reporting good to very physical examination and confirmed by plain radiog- good pain relief in a series of 26 wrists undergoing raphy, arthroscopy, and, occasionally, MRI. A treat- arthrodesis with cancellous bone graft and parallel ment algorithm can be made based on the acuity of K-wires. It is interesting to note that patients with a the injury and the degree of the instability. Acute complete synostosis are generally asymptomatic, stable injuries are amenable to conservative treatment. whereas partial synostosis is associated with ulnar- Acute dynamically unstable injuries can be treated sided pain.35 Thus, one key to long-term success of with arthroscopically assisted percutaneous pinning arthrodesis may be the ability to obtain complete or conservative management. Acute dissociations, fusion. whether isolated or in combination with other inju- If static VISI is present, lunate-capitate-hamate- ries, should be opened and repaired under direct vi- triquetrum fusion should be considered. These treat- sion. The treatment of chronic injuries depends on the ments must be weighed against the options of wrist degree of stability and arthroscopic assessment. Stable fusion or proximal row carpectomy, which are merely injuries may be treated with arthroscopic debride- salvage procedures to relieve pain. ment. Dynamically unstable injuries require arthro- Finally, patients requiring surgical repair should be scopic debridement and pinning. Unstable injuries do assessed properly for ulnar variance, which would best with either a reconstruction or an arthrodesis. result in increased ulnar load bearing and ulnar im- The ultimate choice of treatment will have to reflect paction syndrome. If present, ulnar shortening17 must multiple factors, including patient needs (age, occu- be performed simultaneously, or the repair, recon- pation), associated findings (static VISI, ulnar variance), struction, or fusion most likely will fail. and the experience and preference of the surgeon.

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