Scapholunate stabilization with dynamic extensor carpi radialis longus tendon transfer

Dynamic extensor carpi radialis longus tendon transfer to the distal pole of the scaphoid acts synchronously and synergistically with wrist motion to restore the slider crank mechanism of the scaphoid after scapholunate interosseous ligament (SLIL) injury. The procedure is designed to simulate a hypothetical dorsal radioscaphoid ligament that more closely approximates the normal viscoelastic forces acting on the scaphoid throughout all phases of wrist motion than does the static checkrein effect and motion limitations of capsulodesis or tenodesis. Extensor carpi radialis longus transfer may be independently sufficient to support normal or near-normal scapholunate and midcarpal kinematics and prevent further injury propagation in patients with partial SLIL tears and dynamic scapholunate instability. Extensor carpi radialis longus transfer alone may improve carpal congruity in patients with static scapholunate instability, but SLIL and dorsal lunate ligament repair or reconstruction is essential for favorable durable outcomes. Extensor carpi radialis longus transfer offers a simple and reasonable alternative to capsulodesis or tenodesis to support these ligament repairs or reconstructions, does not require intercarpal fixation, and allows rehabilitation to proceed expeditiously at approximately 1 month after surgery.     

Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: part III

PURPOSE: This study continued our previous investigations of the ligaments stabilizing the scaphoid and lunate in which we examined the scapholunate interosseous ligament, the radioscaphocapitate, and the scaphotrapezial ligament. In this current study, we examined the effects of sectioning the dorsal radiocarpal ligament, dorsal intercarpal ligament, scapholunate interosseous ligament, radioscaphocapitate, and scaphotrapezial ligaments. In the current study, the scapholunate interosseous ligament, radioscaphocapitate, and scaphotrapezial ligaments were sectioned in a different order than performed previously. METHODS: Three sets of 8 cadaver wrists were tested in a wrist joint motion simulator. In each set of wrists, only 3 of the 5 ligaments were cut in specific sequences. Each wrist was moved in continuous cycles of flexion-extension and radial-ulnar deviation. Kinematic data for the scaphoid and lunate were recorded for each wrist in the intact state, after the 3 ligaments were sectioned in various sequences and after the wrist was moved through 1,000 cycles of motion. RESULTS: Dividing the dorsal intercarpal or scaphotrapezial ligaments did not alter the motion of the scaphoid or lunate. Dividing the dorsal radiocarpal ligament alone caused a slight statistical increase in lunate radial deviation. Dividing the scapholunate interosseous ligament after first dividing the dorsal intercarpal, dorsal radiocarpal, or scaphotrapezial ligaments caused large increases in scaphoid flexion and lunate extension. CONCLUSIONS: Based on these findings, we concluded that the scapholunate interosseous ligament is the primary stabilizer and that the other ligaments are secondary stabilizers of the scapholunate articulation. Dividing the dorsal radiocarpal, dorsal intercarpal, or scaphotrapezial ligaments after cutting the scapholunate interosseous ligament produces further changes in scapholunate instability or results in changes in the kinematics for a larger portion of the wrist motion cycle.     

Internal decompression of dorsal wrist ganglions

A technique is described for internal decompression of dorsal wrist ganglions without first rupturing the cyst, including documentation of the ganglion's relation to the scapholunate interosseous ligament. Critical evaluation of the stalk's true origin indicates that dorsal wrist ganglions originate primarily at the synovial-capsular interface between the dorsal scaphoid ridge and the overlying extensor carpi radialis brevis tendon. Although the ultimate etiology of dorsal wrist ganglions still remains unproven, arthroscopic techniques allow a thorough evaluation of the carpal intrinsic and extrinsic ligaments for any associated carpal instability. Despite differences between various arthroscopic methods, the clinical advantages over open techniques remain minimal scarring, avoidance of stiffness after surgery, and a comprehensive joint evaluation.     

Dorsal wrist ligament insertions stabilize the scapholunate interval: cadaver study

This study examined sequential arthroscopic sectioning of volar, interosseous, and dorsal ligaments about the scapholunate complex in cadaver wrists. We attempted to clarify the contributions of the dorsal ligamentous complex to scapholunate instability and carpal collapse. We found that after sequential sectioning of volar ligaments and the scapholunate interosseous ligament, no scapholunate diastasis or excessive scaphoid flexion occurred. After dividing the dorsal intercarpal ligament, scapholunate instability occurred without carpal collapse. With sectioning of the dorsal radiocarpal ligament from the lunate, a dorsal intercalated scapholunate instability deformity ensued. This information may be of value in comprehending the pathogenesis of scapholunate instability and carpal collapse and in devising the rationales for conservative measures and surgical intervention.     

创伤性腕关节不稳定手术治疗

目的 报道创伤性腕不稳定的手术方法。方法 16例腕不稳定中,表现为舟月骨分离6例,以腕背侧镶嵌不稳定(DISI)为主10例。对于舟月骨分离及DISI采用舟月骨间韧带重建手术6例,舟月头骨固定手术3例;对于DISI采用背侧关节囊固定术3例,桡骨远端截骨矫正术4例。结果 术后观察1至2年患者疼痛明显缓解,手握力提高,日常生活满意度改善,功能较术前恢复。结论积极采取手术治疗腕不稳定,重建损伤韧带或纠正畸形,是治疗腕关节不稳定有效的方法。     

Severity of scapholunate instability is related to joint anatomy and congruency

PURPOSE: To determine whether the bony architecture of the distal radius and proximal scaphoid have a role in stabilizing the scaphoid, and to determine whether a relationship between the bony geometry measurements and the amount of wrist constraint could be determined. METHODS: Eight cadaver wrists were tested in a wrist joint motion simulator. The level of scapholunate instability after sectioning the scapholunate interosseous, radioscaphocapitate, and the scaphotrapezium ligaments was determined and related to radiographic measurements of volar tilt, lateral tilt (ulnar tilt of the radioscaphoid fossa), the depth of the radioscaphoid fossa, and 6 radii of curvature measurements of the proximal scaphoid and distal radius. The force to dorsally dislocate the scaphoid out of the radioscaphoid fossa was computed. RESULTS: The radioscaphoid fossa and scaphoid curvatures were larger in those wrists that did not show gross instability after ligamentous sectioning in the wrist simulator. Similarly, those wrists with a deeper radioscaphoid fossa and greater volar tilt were also more stable. The force required to dislocate these wrists was greater than in those wrists that showed gross carpal instability. CONCLUSIONS: This study suggests that the bony anatomy of the radius and scaphoid have a role in stabilizing the carpus after ligament injury. The effect of ligament sectioning on producing carpal instability may be moderated by the bone geometry of the radiocarpal joint. This may explain why some people may have a tear of the scapholunate interosseous ligament but not present with clinical symptoms.     

The occult dorsal carpal ganglion

Chronic wrist pain has many causes, the diagnosis of which is often difficult. Clinical and anatomical research in this area has replaced the diagnosis of "wrist sprain" with a differential diagnosis including carpal chondromalacia, dynamic carpal instability, positive and negative ulnar variance, triangular fibrocartilage complex injuries, and early carpal avascular necrosis. The ubiquitous dorsal ganglion can also cause chronic wrist discomfort and the diagnosis of "occult dorsal carpal ganglion" should be included in the differential diagnosis. Nine patients with chronic wrist pain were diagnosed clinically as having an occult dorsal carpal ganglion despite the absence of a palpable mass. Each was treated by limited dorsal capsulectomy with excision of a small portion of the dorsal scapho-lunate ligament, and small intracapsular ganglia and/or cystic mucinous degeneration of the capsule were found in all nine patients. Of the eight patients available for follow-up examination, the preoperative pain was relieved in seven of the eight and no recurrences were noted at follow-up averaging six months.     

The role of the dorsal intercarpal ligament in dynamic and static scapholunate instability

PURPOSE: Scapholunate instability (SLI) is the most common carpal instability. Recent studies have suggested that the dorsal intercarpal (DIC) and the dorsal radiocarpal ligaments play an important role in stabilization of the scaphoid and lunate. Differences between dynamic SLI and static SLI with a dorsal intercalated segment instability (DISI) are clearly described in the clinical literature; however, there has never been a clear explanation of the anatomic differences. This study describes the role of the DIC in the development of dynamic and static SLI with DISI in a cadaver model. METHODS: Five fresh cadavers were studied radiographically and by 3-dimensional digitization. Six increasing stages of instability were developed by sectioning progressively the following structures: the dorsal capsule, the palmar and proximal (membranous) portion of the scapholunate interosseous ligament, the DIC from its insertion on the scaphoid and trapezium, the dorsal scapholunate interosseous ligament from the scaphoid, the DIC ligament from its attachment on the lunate, and the lunotriquetral interosseous ligament. RESULTS: The scaphoid position and the scapholunate gap changed significantly after sectioning the entire scapholunate interosseous ligament and DIC from the scaphoid when a 5-kg load was applied. The lunate position was unchanged in both the loaded and the unloaded conditions. After detaching the DIC from the lunate, both the scaphoid and lunate moved and the scapholunate gap increased significantly in both loaded and unloaded conditions and showed a DISI deformity. CONCLUSIONS: This study describes an anatomic difference between dynamic and static scapholunate instability. Complete disruption of the scapholunate ligament did not result in the development of a static collapse of the lunate. The DIC had an important role in stabilizing the scaphoid and lunate and preventing DISI deformity. This study suggests that in the clinical setting the DIC ligament should be assessed intraoperatively and consideration should be given to repair and/or reconstruction of the DIC ligament attachments to both the scaphoid and the lunate.     

Patterns of carpal deformity in scaphoid nonunion: a 3-dimensional and quantitative analysis

PURPOSE: To clarify quantitatively the 3-dimensional deformity of the carpus in scaphoid nonunion on the basis of fracture location. METHODS: Three-dimensional computed tomography was used to examine 20 patients with scaphoid nonunion. Displacements of the distal and proximal fragments of the scaphoid, lunate, triquetrum, and capitate were visualized and quantified using a 3-dimensional image-matching technology. Cases were categorized as distal fracture (16 cases) or proximal fracture (4 cases) based on the location of the fracture line relative to the dorsal apex of the scaphoid ridge where the dorsal scapholunate interosseous ligament is attached. RESULTS: The displayed distal scaphoid fractures showed that the proximal fragment of the scaphoid, lunate, and triquetrum rotated into extension and supination. The distal fragment of the scaphoid and capitate translated dorsally without notable rotation. The deformity in proximal fractures was less remarkable than that in distal fractures. Most distal scaphoid nonunions had dorsal intercalated segment instability deformity patterns, whereas a dorsal intercalated segment instability occurred in only 1 case of a proximal fracture. CONCLUSIONS: Whether the fracture line passes distal or proximal to the dorsal apex of the scaphoid determines the subsequent carpal deformity. Dorsal translation of the distal fragment might be one of the factors in the development of degenerative change at the radial styloid.     

The effect of dorsal carpal ganglion excision on the scaphoid shift test

A clinical and radiographic review was performed on 18 patients (19 wrists) with dorsal carpal ganglia and associated positive scaphoid shift test. All patients underwent excision of the ganglion followed by 2 weeks of postoperative immobilization with the wrist in 20 degrees extension. All patients had wrist pain, a painful clunk on the Watson scaphoid shift test, localized tenderness on palpation of the scapholunate articulation and normal radiographs. Patients were assessed postoperatively by questionnaire and physical examination. Improved functional activity and decreased pain were noted in all patients. In 17 of 19 wrists, the positive preoperative Watson scaphoid shift test become negative. We believe that dorsal wrist ganglia are frequently associated with a positive scaphoid shift test and that excision of the ganglion followed by 2 weeks immobilization may lead to resolution of the signs and symptoms of instability, at least in the short term.     

腕舟骨周围韧带解剖学研究

目的观察和研究分布在腕舟骨周围的腕外源性或内源性韧带的结构及特点。方法采用１４侧成人尸体上肢，分离和解剖出舟骨周围的韧带，观察并记录其起止点、行程、长宽度及解剖结构特征。结果在舟骨周围观察到８根韧带，为桡舟头韧带（ＲＳＣ）、桡舟月韧带（ＲＳＬ）、桡月韧带（ＲＬ）、背侧腕间韧带（ＤＩＣ）、桡三角骨韧带（ＲＴ）、和舟月骨间韧带（ＳＬＩＬ）、舟骨大多角和舟骨小多角骨间韧带。ＲＳＣ、ＤＩＣ和ＳＬＩＬ对舟骨的位置、稳定性和运动尤为重要。结论腕舟骨周围存在复杂的韧带结构，其中ＲＳＣ、ＤＩＣ和ＳＬＩＬ对舟骨的稳定，舟骨骨折后畸形的形成、舟骨不稳定的形成起着重要作用。这些韧带的结构或功能在治疗腕不稳定中应予以恢复     

Bone malalignment in acute injuries of the wrist.

The purpose of this study was to analyze radiographic signs of carpal bone instability in patients with an acutely injured wrist. There were 80 patients (52 women and 28 men) with a fall on the outstretched hand. Fifty patients had a fracture of the distal radius, and eight had a scaphoid fracture. The patients with a bone fracture showed a larger scapholunate angle than those without a fracture (P less than 0.001, t-test). However, only four of them showed true carpal bone instability: two patients with a scaphoid fracture and one with a radius fracture had dorsiflexion instability of the wrist and one patient with a radius fracture had dorsal subluxation of the wrist. In addition, one patient without any bone fracture had scapholunate dissociation, one form of carpal bone instability. Although carpal bone instability is not frequent in an acutely injured wrist, its signs should be remembered in the radiographic analysis of the traumatic wrist to prevent subsequent articular disorders.     

The hysteresis effect in carpal kinematics

PURPOSE: Carpal bones show hysteresis that is dependent on the direction of wrist motion during a continuous active loading protocol. We describe an accurate methodology for analyzing the hysteresis effect and we apply this model to analyze the effect of sequential ligament sectioning on scapholunate instability. METHODS: In 8 fresh cadaver forearms scaphoid, lunate, and third metacarpal motions were recorded while each wrist was moved in continuous cycles of active motion in flexion-extension and radioulnar deviation. Motions were analyzed for the intact state and after sequential sectioning of the scapholunate interosseous, scaphotrapezium, and radioscaphocapitate ligaments. Carpal motion was curve-fitted with respect to the third metacarpal motion using optimization criteria. The area between the 2 curves that represents opposite directions of wrist motion was measured to give the total hysteresis area. Repeated-measures analysis of variance was used to determine significance. RESULTS: In the flexion-extension trials the scaphoid and lunate total hysteresis area was significantly greater than the intact state only after all 3 ligaments were sectioned. In the radioulnar deviation trials the scaphoid total hysteresis area was significantly greater than the intact after just scapholunate interosseous ligament sectioning; however, the lunate total hysteresis area decreased with additional sequential sectionings in 4 of the 8 specimens as compared with the intact state. These 4 specimens started with a significantly greater intact total hysteresis area than the other 4 specimens. CONCLUSIONS: The computation of the total hysteresis area from the hysteresis effect was found to be a sensitive technique to determine the subtle onset of abnormal carpal motion. By using this technique in a ligament sectioning study significant increases in the total hysteresis area were seen after just scapholunate interosseous ligament sectioning during wrist radioulnar deviation. This subtle change may signify the onset of dynamic scapholunate instability. The total hysteresis area of the lunate in a subset of lax specimens did not increase after ligament sectioning. This divergent behavior may explain why some patients with scapholunate instability do not develop dorsal intercalated segmental instability.     

Biomechanical evaluation of the ligamentous stabilizers of the scaphoid and lunate: Part II

PURPOSE: This study is a continuation of our previous investigation of the ligaments stabilizing the scaphoid and lunate. We evaluated the effects of sectioning the scapholunate interosseous ligament, radioscaphocapitate ligament, and scaphotrapezial ligament in 3 sequences. METHODS: Three sets of 8 cadaver forearms were placed in a wrist simulator and moved in continuous cycles of flexion-extension and radial-ulnar deviation. Kinematic data for the scaphoid and lunate were recorded for each wrist in the intact state, after the 3 ligaments were sectioned in various sequences and after the wrist was moved through 1,000 cycles of motion. RESULTS: Sectioning only the scaphotrapezium ligament (ST) or the radioscaphocapitate ligament (RSC) resulted in minimal angular changes to the motion of the scaphoid and lunate. Sectioning of the scapholunate interosseous ligament (SLIL) or 1,000 cycles of repetitive wrist motion after ligament sectioning altered scaphoid and lunate kinematics. CONCLUSIONS: Based on these findings it was concluded that the SLIL is the primary stabilizer and the RSC and ST are secondary stabilizers of the scapholunate articulation. Repetitive motion after ligament injury probably results in further carpal instability.     

Anatomic dissections relating the posterior interosseous nerve to the carpus, and the etiology of dorsal wrist ganglion pain

Prompted by the finding of a neuroma, which clinically simulated a recurrent ganglion, we dissected the terminal branches of the posterior interosseous nerve. A constant relationship between these terminal branches and the scapholunate ligament was demonstrated. Since most, if not all, dorsal wrist ganglions arise from the scapholunate ligament, we suggest that the aching wrist pain associated with a dorsal wrist ganglion may be due to a compression neuropathy of the posterior interosseous nerve.     

Scapholunate interosseous reconstruction and imbrication of palmar ligaments

Twenty-eight patients with scapholunate interosseous ligament disruption, carpal instability, and persistent wrist pain were treated by carpal reduction, stabilization, and palmar ligament reconstruction. In twenty-two of these patients pain was well controlled, carpal alignment was maintained, and they were able to resume their previous employment. Grip and pinch strengths averaged eighty-two percent and range of motion averaged seventy-six percent of the normal uninvolved side.     

Carpal ligament injuries with acute scaphoid fractures - a combined wrist injury

Fifty-two consecutive patients with acute scaphoid fractures were treated by closed reduction and percutaneous screw fixation. In addition, all underwent a wrist arthrogram and 22 patients also underwent a wrist arthroscopy. Eighteen patients (34%) had an associated carpal ligament injury (four scapholunate ligament, eight lunotriquetral ligament, two combined, three TFCC and one minor leak from the distal carpal row). These patients had worse Mayo wrist scores (no ligament injury median score=95: ligament injury median score=85) at a mean final follow-up of 61 weeks. We advocate that scaphoid fractures with associated carpal ligament injuries should be defined as a combined wrist injury.     

Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model

The purpose of this study was to evaluate in cadavers a new method for treating scapholunate dissociations, dorsal intercarpal ligament capsulodesis (DILC), and to compare its performance with that of a previously described soft tissue reconstruction, Blatt capsulodesis (BC). A cadaver model was used to simulate normal and abnormal wrist motions. The positions of the scaphoid and lunate and their changes with wrist motion and ligament condition were recorded using biplanar radiographs taken posteroanteriorly and laterally. The scapholunate gap was measured on the posteroanterior radiographs and the scapholunate angle was measured on the lateral view radiographs. Following scapholunate interosseous ligament sectioning, a diastasis developed between the scaphoid and lunate that was maximum in the clenched fist position 2.1 +/- 0.33 mm (mean +/- SEM) with the ligament intact versus 8.0 +/- 1.74 mm after the ligament was sectioned. Dorsal intercarpal ligament capsulodesis reduced gap formation more than BC, including when the specimens were in the clenched fist position: increased gap versus intact specimens equals 1.0 mm for DILC versus 3.7 mm for BC. The differences in diastasis were statistically significant between BC and DILC when the wrist was in extension, radial deviation, and clenched fist positions. After the scapholunate interosseous ligament was divided, the scaphoid flexed relative to the lunate. Both capsulodeses improved scapholunate alignment and there was a trend for DILC to correct the scapholunate angle more than BC. The results demonstrate that DILC is an attractive alternative to BC ex vivo. Because DILC does not tether the scaphoid to the distal radius, as BC does, improved wrist motion, especially flexion, might be possible in vivo. The use of DILC in the treatment of scapholunate dissociation warrants further investigation and clinical trials.     

Radiocarpal articular contact characteristics with scaphoid instability

The relative importance of the three major periscaphoid ligament complexes in maintaining the normal radiocarpal articulation was assessed. Pressure-sensitive film recorded the changes in radioscaphoid and radiolunate articular contact that occurred with sequential ligament sectioning in 12 cadaver wrists. Alterations in the radiocarpal articular contact as a result of ligament disruption are evident in the absence of the recognizable static x-ray changes of carpal instability. The scapholunate interosseous ligament is essential in preventing scapholunate diastasis and dorsoradial subluxation of the proximal scaphoid. Rotatory subluxation of the scaphoid occurs when disruption of the scapholunate interosseous ligament is coupled with disruption of either the palmar intracapsular radiocarpal ligaments or the scaphotrapezial ligament complex. These data help explain the development of degenerative arthritis caused by carpal ligamentous instability.     

Scapholunate ligament repair with capsulodesis reinforcement

The typical presentation of an acute scapholunate dislocation is swelling, pain, and deformity following acute trauma to the wrist. Radiographs corroborate a gross disturbance of carpal relationships. In a dorsal perilunate dislocation, the lateral radiograph shows the longitudinal axis of the capitate dorsal to the longitudinal axis of the radius and the proximal pole of the scaphoid rotated dorsally. A scapholunate angle of greater than 70 degrees on the lateral view is 1 accepted radiographic criterion for identifying an acute scapholunate dissociation. In the posterior-anterior (PA) projection, the carpus is foreshortened. A scapholunate interval of >2 mm is seen on the PA x-ray (Terry Thomas sign). The lunate is triangular instead of quadrangular in shape. Although closed reduction is possible, maintaining an anatomical reduction is extremely difficult. Therefore, all of these injuries require open reduction and internal fixation and repair of the scapholunate interosseous ligament. Although originally advocated for the treatment of some forms of chronic scapholunate dislocations (>3 months old), dorsal capsulodesis can be useful to reinforce the scapholunate interosseous ligament repair in the subacute setting (>3 weeks old).