Carpal Ligament Instability

Updated: Aug 24, 2022
Author: Sunjay Berdia, MD; Chief Editor: Harris Gellman, MD 


Practice Essentials

Carpal ligament instability has been broadly defined as any malalignment of the carpus. This may be evident on plain radiography as a static deformity; alternatively, the situation may be a dynamic one, which becomes evident only when external forces are placed on the wrist. The malalignment may appear after a single traumatic event or may be secondary to chronic attenuation of supporting ligaments after a traumatic event or secondary to an underlying disease process (eg, rheumatoid arthritis,pseudogout).

Others have stressed the importance of distinguishing misalignment from true instability and pointed out that an alteration of carpal alignment is not always pathologically unstable.[1, 2] This view suggests a somewhat narrower definition of carpal instability.

The human wrist joint is a complex arrangement of small bones and ligaments that form a mobile yet stable link from the powerful forearm to the hand. The normally functioning carpus can position the hand precisely relative to the forearm and provides remarkably stable transmission of forces. Motion and stability of the carpus provide the critical foundation for maximum hand function from precise fine motor control to power grip activities.

When the normal mechanics of the wrist are disrupted, the instability of the carpal bones results in weakness, stiffness, chronic pain, and often arthritis if not treated appropriately. Although the early clinical and radiographic findings may be subtle, an understanding of wrist kinematics and instability patterns can facilitate early diagnosis and management. Unfortunately, selecting the optimal treatment remains a difficult judgment in most cases.

Linscheid et al described traumatic carpal instability in 1972.[3] Since the early reports, anatomic and biomechanical studies have provided a foundation for understanding carpal motion, stresses, and pathologic instability.[4, 5] Building on these studies, various models have been suggested to explain the remarkable strength and mobility of this complex joint and the predictable patterns of failure.

This article presents concepts of pathologic carpal instability, common classification patterns, and early treatment options that may avoid protracted dysfunction. Treatment of wrist instability remains a hotly debated topic among hand surgeons. Such treatment is necessarily complex and is usually specific to the type of instability present. Appropriate hand therapy is essential to maximize recovery but requires an appreciation of the limitations of carpal instability dysfunction and the goals of various treatment options.


Carpal bones

The wrist contains eight carpal bones. Anatomically and functionally, these bones are divided into proximal and distal rows. The proximal row is formed by the scaphoid, the lunate, and the triquetrum. Although the pisiform is anatomically located on the palmar surface of the proximal row, it is a sesamoid bone within the flexor carpi ulnaris tendon; it does not contribute to the kinematics of the proximal row. The trapezium, the trapezoid, the capitate, and the hamate form the distal row.

Carpal ligaments

Multiple ligaments help stabilize the wrist to the forearm and hand. Extrinsic ligaments span the radiocarpal joint, whereas intrinsic ligaments form connections between individual carpal bones.


An important extrinsic ligament on the dorsal aspect of the wrist is the dorsal radiocarpal ligament (see the first image below). This ligament originates on the radius and has minor attachments to the lunate, with the bulk of the attachment on the triquetrum. There are many more extrinsic ligaments on the volar aspect of the wrist. From radial to ulnar, they include the radioscaphocapitate, radioscapholunate, short radiolunate, long radiolunate, ulnolunate, and ulnotriquetral ligaments (see the second image below).

(Click image to enlarge.) Dorsal carpal ligaments. (Click image to enlarge.) Dorsal carpal ligaments. Copyright Mayo Clinic, used with permission of Mayo Foundation.
(Click image to enlarge.) Volar carpal ligaments. (Click image to enlarge.) Volar carpal ligaments. Copyright Mayo Clinic, used with permission of the Mayo Foundation.


The intrinsic ligaments are stout structures that originate and insert within the carpus. The two most important intrinsic ligaments are the scapholunate interosseous ligament (SLIL) and the lunotriquetral interosseous ligament (LTIL). The SLIL, which joins the scaphoid and the lunate, is probably one of the most important ligaments in the wrist. Injury of the SLIL can result in one of most common causes of carpal instability: scapholunate dissociation.

The SLIL is a C-shaped ligament that is divided into three separate components, as follows[6] :

  • The proximal component is made up of fibrocartilage and has minimal mechanical strength
  • The other two components, the dorsal SLIL (dSLIL) and the palmar SLIL (pSLIL), have true ligament characteristics; the dSLIL is stouter than the pSLIL

The LTIL connects the lunate and triquetrum. Like the SLIL, the LTIL is C-shaped and has three separate components. Unlike the SLIL, it has a palmar component that is stouter than its volar component.

Two intrinsic ligaments that cross from the proximal row to the distal row are the scaphocapitate ligament and the dorsal intercarpal ligament. The scaphocapitate ligament crosses the volar midcarpal joint and attaches from the distal pole of the scaphoid to the body of the capitate. Across the dorsal midcarpal joint, the dorsal intercarpal ligament originates from the triquetrum, attaches to the scaphoid dorsal ridge, and then inserts into the dorsal distal third of the scaphoid and to the scaphoid-trapezium ligament.


Column theory of carpal kinematics

Over the past several decades, many theoretical models have been described to explain the complexities of carpal motion. The column theory, first proposed by Navarro in 1935,[7] recognized some motion between the bones of the proximal row and divided the wrist into the following three columns:

  • Radial column, consisting of the scaphoid, the trapezium, and the trapezoid
  • Central column, including the lunate and the capitate
  • Ulnar column, consisting of the triquetrum and the hamate

Although this theory does not explain the coupled motions that occur within the proximal and distal rows, it does help explain the load patterns seen through the wrist.

Row theory of carpal kinematics

The row theory of carpal kinematics is based on the observation that the proximal and distal rows work as two separate functional units. Gilford et al expanded on this theory by noting that flexion-extension motions of the wrist are accomplished by relatively equal contributions from the radiolunate and lunocapitate joints, and they proposed that each row rotates around a single center of rotation near its proximal articular surface (see the image below).[8]

The scaphoid acts like a bridge between the proxim The scaphoid acts like a bridge between the proximal and distal row and protects the link from collapsing.

Gilford et al also emphasized the instability of such a two-link system under load and the tendency for the system to crumple without a stabilizing mechanism.[8] They believed that the scaphoid should be considered part of both rows and underscored its importance as a bridge, or tie rod, to stabilize an otherwise unstable arrangement (see the image below).

The wrist is a simple link between the proximal an The wrist is a simple link between the proximal and distal rows. The pivot point is at the center of rotation of the capitate and lunate. This joint, without other supporting structures, is stable only in tension. It is unstable in compression, as this figure depicts, and tends to collapse.

Because no tendons insert on the scaphoid, lunate, and triquetrum, in 1972 Linscheid et al considered the scaphoid, lunate, and capitate to be an intercalated segment interposed between the articular surfaces of the radius and ulna and the rigidly bound distal carpal row.[3]

Muscle contractions impart rotational moments to the proximal row through the distal row, and carpal motion is governed by a combination of ligamentous and articular constraints. The strong interosseous ligaments between the three proximal carpal bones enable them to move in a synchronized fashion during wrist motion. The scaphoid, lunate, and triquetrum rotate in the same primary direction, albeit to different magnitudes, during any motion of the hand.

A specific example of this interaction may be observed during radial-ulnar deviation. As the wrist deviates ulnarly, the entire proximal row extends. Conversely, as the wrist deviates radially, the entire proximal row flexes. Although the mechanism by which this occurs has not been fully elucidated, most authors believe that this motion is a result of a combination of ligamentous constraints and carpal articular geometry between the proximal intercalated row and the distal row.

A theory proposed by Linscheid and Dobyns in 1989 was that the distal pole of the scaphoid flexes because of pressure by the trapezium and trapezoid during radial deviation.[9] The rest of the proximal row then flexes because of the strong interosseous ligaments connecting the lunate to the scaphoid and the triquetrum to the lunate.

In another theory, Weber proposed that the unique helicoidal shape of the triquetrohamate articulation forces the distal row to translate dorsally and the triquetrum to tilt into extension as the wrist deviates ulnarly.[10] Dorsal translation of the distal row contributes to an extension moment on the proximal row. The opposite occurs during radial deviation with palmarly directed force on the proximal row, causing flexion.

Combined column-row theory of carpal kinematics

Some have theorized that an individual's carpal kinematic behavior can be explained by some combination of the columnar theory with the row theory.

Craigen and Stanley analyzed radiographs of 52 normal wrists and found that from ulnar deviation to radial deviation, the amount of scaphoid shortening and ulnar translation of the scaphoid varies in a normal distribution.[11] If the scaphoid shortens more, it translates less. By their interpretation, a column-type wrist shows greater shortening. They also found that females were more likely to have greater scaphoid shortening and less translation.

This individual variation in kinematic behavior was also supported by Garcia-Elias et al, who attributed it to individual variation in laxity.[12] They examined 60 healthy volunteers and found that physiologic differences in wrist ligamentous laxity affected carpal kinematics. In radial-ulnar deviation, the scaphoid of very lax wrists moved preferentially in the sagittal plane (flexion-extension), whereas in the more rigid wrists, the scaphoid moved preferentially in the frontal plane (radioulnar deviation).

Oval-ring theory of carpal kinematics

The oval-ring theory functionally depicts the carpus as a transverse ring formed by proximal and distal rows and joined by two physiologic links, one radial and the other ulnar.[13] The radial link is the mobile scaphotrapezial joint, and the ulnar link is the rotatory triquetrohamate joint.


Carpal ligament instability results from an injury to one or more ligamentous or bony constraints in the wrist. Depending on the force, rate, and point of impact and on the position of the wrist, a fall on an outstretched wrist can result in a range of injuries, including the following:

This type of trauma can also result in injury to one or more ligamentous structures in the wrist, causing carpal instability. Perilunate instability is described as progressing from the scapholunate and the capitolunate to the lunotriquetral joint.

Using a cadaveric trauma model, Mayfield et al observed progressive injury patterns when the wrist was loaded in extension, ulnar deviation, and carpal supination.[14] This perilunar instability is divided into the following four stages (see the image below):

  • Stage I - The SLIL is injured
  • Stage II - Further trauma results in dorsal subluxation of the capitate relative to the lunate
  • Stage III - As the load increases, the LTIL is injured, causing a perilunate dislocation
  • Stage IV - The lunate is dislocated from the radiolunate fossa
Mayfield perilunate instability pattern. Copyright Mayfield perilunate instability pattern. Copyright Mayo Clinic, used with permission of the Mayo Foundation.

However, if the carpus is pronated and the hypothenar area is struck first, an ulnar traumatic pattern may be observed. Specifically, disruption of the ulnotriquetral ligament complex and the LTIL occurs.[15] As the triquetrum no longer holds the lunate, it falls into a flexed position because of pressure from the capitate and its connection with the scaphoid. With attenuation or injury to the dorsal intercarpal ligament, a volar intercalated-segment instability (VISI) pattern ensues; this can be visualized on lateral radiography. An LTIL tear most commonly results in a VISI deformity.

In addition to a direct loading type of trauma, rotational force to the wrist can also result in ligamentous injuries—for example, the forces that occur when one holds a power drill while the drill bit is jammed. This type of trauma can result in injuries to the LTIL and ulnotriquetral ligament complex and result in the lunotriquetral instability.[16]

Some instability patterns arise after chronic attrition of supporting ligaments. One traumatic event may result in some subtle ligamentous injury but no clear instability initially. However, over time, continued normal daily loading of the wrist can result in symptomatic instability. An example is seen with scaphoid fractures, where a dorsal intercalated-segment instability (DISI) deformity tends to appear late after the initial traumatic event.

Supporting ligaments can also be important in preventing carpal instability in the presence of other significant ligamentous injury. For example, many cadaveric studies have shown that isolated sectioning of the SLIL does not result in a frank radiographic scapholunate gap or dissociation.

In 1986, Johnson and Carrera described a midcarpal instability in which the capitate dorsally subluxates out of the cup of the lunate during a fluoroscopic dorsal-displacement stress test.[17] This is associated with a painful snap or click that reproduces the patient's symptoms. They attributed the cause of this instability to attenuation of the radioscaphocapitate ligament after prior trauma.

Paul et al found that trapeziectomy in the treatment of trapeziometacarpal arthritis could adversely affect carpal stability and therefore should be performed with caution in wrists with dynamic or static carpal instability.[18]


In 1975, Dobyns et al reviewed their experience and found that 10% of all carpal injuries resulted in instability.[19]

In 1988, Jones evaluated 100 consecutive patients with wrist sprains by using dynamic radiography (clenched-fist views) and found that 19 had an increased scapholunate gap.[20]

The incidence of carpal instability that is associated with other specific fractures is relatively high. Reviewing 134 distal radius fractures, Tang in 1992 found radiographic evidence of carpal instability in 30% of the cases.[21]

Geissler and Freedland prospectively reviewed 60 displaced intra-articular distal radius fractures that were being treated with arthroscopy-assisted reduction and internal fixation.[22] They found that 43% had concomitant tears in the fibrocartilage complex and 32% also had tears in the scapholunate ligament.

Weber reviewed 36 patients with acute scaphoid waist fractures and found that 28% had a DISI deformity.[23]




The diagnosis of carpal instability in patients with obvious fracture and carpal instability patterns on radiography is sometimes relatively easy. Making the diagnosis in patients with subtle carpal instability can be more difficult. These patients often present with a history of a traumatic event. Noting the position of the wrist at the time of injury and determining the resultant force vector are extremely valuable.

Patients may have pain; if so, its location can be important when making the diagnosis. They may also have weakness and feelings of giving away. They may have clicking or snapping sensations on certain motions or upon loading the wrist.

Physical Examination

As in many situations, physical examination starts with palpation. Nearly every critical ligament on the wrist can be palpated. Point tenderness over specific carpal ligaments, such as the scapholunate interosseous ligament (SLIL) or the lunotriquetral interosseous ligament (LTIL), may represent injuries to those ligaments. Pain at the extremes of motion may be present. Many dynamic maneuvers have been described to diagnose specific carpal instabilities.

Scaphoid shift test

One of the most common tests is the scaphoid shift test, described by Watson described in 1997 (see the image below).[24] In this test, the examiner's thumb is placed on the scaphoid tuberosity of the volar aspect of the wrist. Pressure is applied to the tuberosity as the wrist is passively brought from ulnar to radial deviation. This pressure attempts to block normal scaphoid flexion.

(Click Image to enlarge.) Watson scaphoid shift te (Click Image to enlarge.) Watson scaphoid shift test.

In theory, if the SLIL is torn and scapholunate instability is present,[25] the proximal scaphoid subluxates dorsally over the rim of the radius. A positive result is obtained if a painful "clunk" is elicited as the scaphoid reduces back into the radial scaphoid fossa when the thumb pressure is released.

Easterling and Wolfe showed that the results of this test may be positive in a significant number of asymptomatic healthy wrists.[26] Therefore, examination of the contralateral uninjured wrist is critical. In addition to the classic definition of a positive result, some surgeons believe that when the maneuver elicits only pain and no subluxation, this may signal a lesser scapholunate instability, such as a partial tear of the SLIL.

Maneuvers for diagnosing lunotriquetral instability

A few maneuvers have been described that can help diagnose lunotriquetral instability. It is important to distinguish lunotriquetral instability from a tear in the triangular fibrocartilage.

The Kleinman shear test (see the image below) is performed with the wrist in neutral position.[27] The examiner's contralateral thumb is placed over the dorsal lunate while the ipsilateral thumb loads the pisotriquetral joint with a dorsally directed force. A shear force is created across the lunotriquetral joint. A positive result is obtained when this maneuver produces pain.

(Click Image to enlarge.) Kleinman shear test. (Click Image to enlarge.) Kleinman shear test.

The Reagan shuck test (see the image below) is similar, except that the examiner's thumb and index finger grasp the whole pisotriquetral unit.[28] The contralateral thumb and index finger hold the lunate. The lunotriquetral joint is stressed by applying dorsally directed force with one hand and volarly directed force with the other hand. This force is switched in the opposite directions in both hands. This creates a shear stress at the lunotriquetral joint. If pain is elicited, the result is positive.

Reagan shuck test. Reagan shuck test.

Linscheid described a compression test in which the examiner uses a thumb to apply a load in the radial direction at the ulnar border of the triquetrum (see the image below).[29] This loading results in a compression force across the lunotriquetral joint. If this maneuver produces pain, the result is considered positive.

Linscheid compression test. Linscheid compression test.

Lichtman et al described a pivot shift test for midcarpal instability.[30] This maneuver is a combination ulnar deviation, axial compression, and pronation of the wrist. A positive result is obtained when this maneuver results in a painful wrist click.

Another test for midcarpal instability (as described above) is a dorsal-displacement stress test.[17] Under fluoroscopic control, a positive result is obtained when the capitate subluxates dorsally as compared with the lunate and when the patient experiences a painful snap or click.



Imaging Studies

Plain radiography

Standard radiographic examination of the wrist should include a posteroanterior (PA) view in neutral rotation, as well as lateral views. Both the symptomatic and the asymptomatic wrist should be evaluated. Static instability patterns can be seen with these radiographs. Additional radiographs (eg, PA grip, PA maximum radial deviation, PA maximum ulnar deviation, lateral maximum flexion, and lateral maximum extension views) can also be obtained and can help diagnose dynamic instability.

To determine scapholunate dissociation, the scapholunate gap can be measured on PA and PA grip radiographs. However, obtaining a PA view that clearly shows the scapholunate gap without some bony overlap can be difficult. Findings should always be compared side to side.[31]  Kindynis et al suggested angling the x-ray tube to obtain a clearer view of the scapholunate joint and to measure the space at the level of the midportion of the flat ulnar facet of the scaphoid.[32]

The amount of gap that is diagnostic of scapholunate dissociation has been a subject of debate. Many authors have defined the gap as pathologic if it exceeds 3 mm.[29, 33] In 1991, Cautilli and Wehbe measured the gap on 100 normal radiographs and found a mean distance of 3.7 mm (range, 2.5-5 mm). Given the wide range, comparing the injured wrist with the contralateral uninjured wrist is crucial before scapholunate dissociation is diagnosed.

If the lunate is dorsiflexed more than 15º than the capitate on lateral radiography, the diagnosis of a dorsal intercalated-segment instability (DISI) deformity is confirmed. Conversely, a volar intercalated-segment instability (VISI) deformity is defined if the lunate if volarly flexed more than 15º. A DISI deformity is associated with scapholunate instability, whereas a VISI deformity is associated with lunotriquetral instability.

In addition, the scapholunate angle (SLA) can be measured on lateral radiography. In scapholunate instability, the scaphoid tends to assume a volarly flexed posture. Consequently, the SLA, which normally measures 30-60º (average, 46º), increases to more than 70º.[3]  Conversely, in lunotriquetral instability, the lunate is usually palmarly flexed, and the SLA can be less than 30º.[33]

Rachunek et al (N = 414) retrospectively studied the utility of static and dynamic radiographs for diagnosis of SLIL injury as compared with the surgical records of arthroscopies.[34]  The parameters found to have the highest diagnostic value were scapholunate distance (SLD) in ulnar inclination, SLD in PA projection, and SLA. Further investigation of SLIL pathology was considered appropriate in the case of an SLD of 2.7 mm in ulnar inclination, an SLD of 1.9 mm in PA projection, and an SLA of 63°. 

McMurty et al defined a method to determine ulnar translocation on PA radiography (see the image below).[35]  The distance between the center of the capitate and a line extending from the intermedullary axis of the ulna is divided by the length of the third metacarpal. McMurty et al found that this ratio was 0.30 ± 0.03 in normal wrists but was smaller in patients with ulnar translocation.

McMurty ulnar translation measurement. McMurty ulnar translation measurement.

Other imaging modalities

Other diagnostic imaging studies that may be considered in this setting include the following[36, 37] :

  • Fluoroscopy
  • Wrist arthrography
  • Computed tomography (CT)
  • Magnetic resonance imaging (MRI)
  • Ultrasonography (US)

Wrist cineradiography has been shown to be a good modality for diagnosing carpal instability.[38]

Because the false-positive rate is relatively high for arthrography (especially in those >40 y), some have suggested comparing images of the injured wrist with images in the contralateral uninjured wrist.[39]  Communication between the different compartments of the wrist may not be a result of trauma but, rather, may be a result of age-related degenerative changes.[40]

Arthroscopy remains the criterion standard for diagnosing specific ligament injuries in the wrist.[41, 42, 43, 44]  Both radiocarpal and midcarpal joints should be evaluated. More important, surgical management can take place in the same setting.

Leng et al studied a proposed dynamic four-dimensional (4D) CT imaging technique that generated images with high spatial and temporal resolution without requiring periodic joint motion.[45] Preliminary results from this cadaveric study demonstrated the feasibility of detecting joint instability using this technique. A study by Athlani et al (N = 40) found 4D CT to be a quantitative and reproducible tool for the evaluation of DISI deformity in cases of scapholumate instability.[46]

Abou Arab et al found that kinematic CT was effective for quantitative assessment of scapholunate dissociation.[47]  Flat-panel cone-beam CT arthrography has been suggested as a means of diagnosing scapholunate ligament tears.[48]


Many schemes have been described to classify the different degrees of carpal instability. The one described by Linscheid et al is one of the earliest and probably the easiest to use.[30, 3]

Linscheid et al separated most instabilities into two groups on the basis of the orientation of the proximal row relative to the distal row. They used the lunate to define the orientation of the proximal row, and they used the capitate to define the orientation of the distal row because it is most easily seen on lateral radiography. In this system, if the lunate is dorsally flexed relative to the distal row (capitate) on lateral radiography, the instability is considered a DISI. The proximal row is the intercalated segment because no tendons directly insert on it. Similarly, if the lunate is palmarly flexed relative to the distal row, the instability is defined as a VISI.

These two patterns have been further subclassified into dissociative and nondissociative types.[2, 1] The dissociative type occurs when the injury results in instability between adjacent carpal bones within a row. For example, scapholunate instability is most commonly associated with a dorsiflexed lunate; this pattern is called a DISI deformity, dissociative type. Dissociative carpal instability is also referred to as carpal instability dissociative (CID).

A nondissociative type occurs when the DISI or VISI pattern is secondary to an injury that results in instability between rows. This nondissociative pattern has also been called midcarpal instability or carpal instability nondissociative (CIND).

Another type of carpal instability, carpal instability complex (CIC), exhibits characteristics of both CID and CIND.

Two patterns that do not fit this classification are ulnar translocation and dorsal subluxation of the carpus. Ulnar translocation is defined as an ulnar shift of the entire carpus relative to the radius. This type of instability is seen in wrists with rheumatoid arthritis after chronic attrition of radial-side extrinsic ligaments and bony changes. Dorsal subluxation describes a dorsal shift of the entire carpus relative to the radius. This pattern, also called adaptive carpal instability, is often seen after malunion of distal radius fractures where the radius has lost its normal volar tilt.

Two other adjectives commonly used in classifying carpal instabilities are static and dynamic. A static instability is one that can be clearly recognized on routine radiography by a loss of the normal alignment.[49]  A dynamic instability is any instability that requires external forces placed on the carpus to elicit an instability pattern. Therefore, the diagnosis of dynamic instability relies on other means, such as dynamic radiography, physical examination with provocative maneuvers, or arthroscopic evaluation.



Approach Considerations

Although the diagnosis of wrist instability has been known for decades, the treatment of wrist instability remains a hotly debated topic among hand surgeons. Such treatment is necessarily complex and is usually specific to the type of instability present. A full, detailed review of all of the available treatment options is beyond the scope of this article. To simplify the discussion, treatment is summarized below under the headings of the following specific types of instabilities:

  • Scapholunate instability
  • Lunotriquetral instability
  • Midcarpal instability
  • Ulnar translocation

Surgical Therapy

Scapholunate instability

There is no consensus on the appropriate treatment of scapholunate instability. The treatment is usually specific to the different stages or degree of injury.[50, 51] Partial tears of the scapholunate interosseous ligament (SLIL) are thought to represent occult or predynamic instability.[24, 52] For these injuries, most recommend an initial trial of splinting, casting, or both.[52, 53] Arthroscopic debridement with or without pinning can be an option in these patients in whom initial conservative treatment is unsuccessful.[54, 55]

A complete tear of the SLIL may not by itself lead to an acute scapholunate gap or diastasis. Biomechanical studies support the concept that additional supporting ligaments must also be injured for this gap to be apparent. In addition, attenuation of these ligaments may lead to a diastasis that is observed late with respect to the initial injury date. In either case, a complete tear of the SLIL is suggested in the presence of a significant scapholunate diastasis on static or dynamic radiography.

With complete SLIL tears, cast immobilization does not reduce or prevent scapholunate diastasis.[52] Significant force occurs at the scapholunate interval on wrist loading. Options for acute management of these tears include the following:

  • Direct repair with or without dorsal capsulodesis
  • Arthroscopic debridement, reduction, and pinning

Some recommend the latter treatment for acute (< 3 mo) tears that have evidence of instability on static radiography (gap < 3 mm or dorsal intercalated-segment instability [DISI]).[54, 55]  A retrospective study by Weiss et al showed that 33% of patients who underwent arthroscopic debridement, reduction, and pinning of complete SLIL tears had persistent pain and required further surgery.[56]

In a study involving 17 patients with chronic scapholunate instability (average duration, 9.5 mo), 13 of whom had a DISI deformity, Ho et al described an arthroscopy-assisted minimally invasive approach to repair of both the dorsal SLIL component and the volar component.[57] At an average follow-up of 48.3 months, 13 patients had returned to their preinjury job level, 11 had no wrist pain, and six had some pain on either maximum exertion or at the extreme of motion. There were no major complications, and all of the patients were satisfied with the operation and its outcome.

Most reconstructive wrist surgeons recommend direct repair for acute (< 6 wk) tears if a sufficient SLIL remnant is present.[52, 58] Lavernia et al reported on dorsal capsulodesis to augment a direct repair and demonstrated good results in 81% of their patients.[59] Satisfactory results were seen even as long as 3 years after injury.

In patients with an unrepairable SLIL but a reducible scapholunate interval and without degenerative changes, an indirect or direct ligament reconstruction has been advocated. Typically, the presentation is chronic, and the SLIL is usually not repairable. Indirect ligament reconstruction is based on stabilizing the scaphoid to prevent the rotatory subluxation that often occurs in scapholunate instability.

Some indirect ligament reconstructions also attempt to close the scapholunate gap. The most widely used indirect ligament reconstruction is the Blatt dorsal capsulodesis.[60] This technique uses a flap of dorsal capsule to tether the scaphoid tuberosity to retard scaphoid flexion. Because the flap is attached to the distal radius, wrist flexion is significantly reduced by 20% on average.

Other techniques attempt to avoid limitation of flexion by not tethering the scaphoid to the radius.[61, 62] Several such techniques have been described. As Berger et al initially proposed,[20] a strip of dorsal intercarpal ligament detached from the triquetrum can be used to tether the distal scaphoid pole to the lunate or radius (see the image below). Slater et al used a portion of the dorsal intercarpal ligament that attaches to the distal scaphoid and trapezoid and reinserted it to the distal pole of scaphoid tuberosity.[62] These authors believe that this technique not only serves to limit scaphoid flexion but also reduces the scapholunate gap more effectively than the Blatt capsulodesis does.

Mayo dorsal intercarpal (DIC) capsulodesis. Copyri Mayo dorsal intercarpal (DIC) capsulodesis. Copyright Mayo Clinic, used with permission of Mayo Foundation.

Direct ligament reconstruction is indicated when the SLIL is not directly repairable, when the scapholunate dissociation is reducible, and when no evidence of degenerative arthritis is observed. Some also believe that evidence of carpal instability (DISI) should be absent.[52]

Techniques for this approach involve either a tendon to reconstruct the SLIL or a bone-ligament-bone construct.[52, 63, 64, 65, 66] All of these techniques have had some degree of success, but they are not universally durable. They require a long period of wrist immobilization and result in some loss of final wrist motion.

Brunelli and Brunelli described one such technique that showed promise.[64] Their technique used a strip of the flexor carpi radialis (FCR) and wove it through the scaphoid. The tendon was also sutured across the scapholunate interval. Limited intercarpal fusions are indicated when carpal instability (DISI) is present without gross evidence of degenerative changes at the radiocarpal joint.[52]

Fusions that have been described involve the scaphocapitolunate,[67] the scaphotrapezial trapezoid,[27, 68, 69, 70, 71] the scaphocapitate,[72] and the scapholunate.[73] Viegas et al found that the scaphocapitolunate and scapholunate fusions distributed the load more uniformly across both the scaphoid and lunate fossae than the scaphotrapezial trapezoid or scaphocapitate fusions.[74]

For studies of other techniques, see Garcia-Elias[75] , Ogunro[76] , Short[77] , and Danoff.[78]

When arthritic change (advanced scapholunate collapse) or a wide, irreducible scapholunate gap is present, options include proximal-row carpectomy or scaphoid excision and fusion of the lunate, triquetrum, capitate, and hamate (four-corner fusion). Significant degenerative changes at the proximal hamate or of the lunate fossa are a contraindication for proximal-row carpectomy. Once pancarpal arthritis involves the lunate fossa, the best surgical option may be total wrist fusion.

Lunotriquetral instability

There is no consensus on the appropriate treatment of lunotriquetral instability. The treatment algorithm can probably be based on the type and age of the injury. A partial tear of the lunotriquetral interosseous ligament (LTIL) may be clinically suspected and should not have the associated volar intercalated-segment instability (VISI) deformity. Reagan et al recommended a period of immobilization for acute injuries.[28] Others have recommended arthroscopic evaluation and percutaneous pinning.[16]

For patients in whom conservative treatment fails, lunotriquetral dissociation direct repair with or without augmentation has been advocated. Repairing the LTIL by using an open technique to reattach it back to the site of its avulsion (usually from the triquetrum) has good results.[28] Augmentation is usually in the form of a capsulodesis. The goal of capsulodesis is to prevent excessive flexion of the proximal row by imbricating the dorsal radiotriquetral ligament.[16]

For patients who present late after their initial injury, surgical management includes the following:

  • Capsulodesis
  • Ligament reconstruction
  • Arthrodesis
  • Ulnar shortening

Shin et al described a ligament reconstruction that used a distally based strip of the extensor carpi ulnaris tendon.[79]  Pillukat et al found this approach to yield a high percentage of good-to-excellent results, with only rare complications.[80]

Because some patients with symptomatic lunotriquetral instability also have ulnar impaction syndrome, Ruby treated these patients with chronic lunotriquetral tears with ulnar shortening alone, especially if they have positive or neutral ulnar variance.[16] Ulnar shortening is believed to tighten the volar ulnotriquetral and ulnolunate ligaments, thereby indirectly improving lunotriquetral stability. However, this treatment may be ill advised in the patient with a VISI deformity, because tightening of these volar ligaments may exacerbate the deformity.

As a treatment for lunotriquetral instability, lunotriquetral fusion is controversial. Pin et al used a compression screw and achieved fusions in all 11 patients in their study.[81] Three patients (27%) had persistent pain, and the 11 patients achieved a postoperative grip strength of only 59% as compared with the uninjured side.

Kirschenbaum et al reported results after lunotriquetral fusion that were slightly better.[82] Among 14 patients, only one had persistent pain, and the average grip strength was 94% as compared with the contralateral side. In two patients, fusion did not occur: One underwent repeat fusion, whereas the other was not symptomatic. Wrist motion was also well preserved in this series: about 80-85% as compared with the uninjured wrist.

The results of these two studies notwithstanding, others authors have reported nonunion rates as high as 57%, persistent pain in 52%, and decreased in wrist motion in 31%.[83]

Instead of lunotriquetral fusion, some authorities have recommended lunotriquetrohamate[33] or triquetrohamate[15] fusions. Further studies are needed to fully evaluate these fusions.

Midcarpal instability

Johnson and Carrera advocated tightening the radiocapitate ligament in patients who had a positive result on fluoroscopic dorsal-displacement stress testing.[17] Their technique consists of tethering the middle portion of the radiocapitate ligament to the radiotriquetral ligament to close the space of Poirier. Slight extension of the wrist is lost after this procedure.

Lichtman et al reviewed 13 patients (15 procedures) who underwent surgery for midcarpal instability over an 8-year period. They found that all six of the limited midcarpal arthrodeses were successful, whereas six of the nine soft-tissue reconstructions failed.[13]

Carpal instability that results from distal radius malunion can be effectively treated by correcting the malalignment of the radius. Opening wedge osteotomy of the radius at the location of the deformity to correct radial malalignment usually also corrects the carpal instability.

Chaudhry et al described a soft-tissue stabilization technique using a palmaris longus graft in six patients (seven wrists) with palmar midcarpal instability.[84]  They achieved good medium-term results in most cases; the procedure retained some midcarpal mobility, eliminated "clunking" in most patients, and provided a noteworthy improvement in grip strength and function. Further evaluation in larger studies with a longer follow-up would be required to assess the value of this approach.

In a study of 23 consecutive patients (12 male, 11 female; average age, 27 y) with 27 symptomatic wrists, von Schroeder treated midcarpal instability with an initial 6 weeks of full immobilization followed, in cases of recurrence, by plication of the dorsal capsule and extrinsic ligaments to stabilize the midcarpal joint; if plication failed, four-corner intercarpal arthrodesis was performed (n = 2).[85] All patients had less pain at final follow-up. Female patients younger than 25 years with hypermobility and without major traumatic or work-related injuries had the greatest improvements; outcomes were poorer in men older than 25 years with moderate or severe trauma (mostly work-related).

Ulnar translocation

In the rheumatoid wrist, ulnar translocation is usually effectively treated with radiolunate fusion.[86] Significant arthritis at the radioscaphoid joint may also require radioscaphoid fusion. Total wrist fusion is probably the best option if significant midcarpal arthrosis is present as well.