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Radiographic Evaluation of the Modified Brunelli Technique Versus the Blatt Capsulodesis for Scapholunate Dissociation in a Cadaver Model
SCIENTIFIC ARTICLE
Radiographic Evaluation of the Modified Brunelli Technique Versus the Blatt Capsulodesis for Scapholunate Dissociation in a Cadaver Model Patrick J. Pollock, MD, Ryan N. Sieg, MD, Martin F. Baechler, MD, Danielle Scher, MD, Neal B. Zimmerman, MD, Norman H. Dubin, PhD
Purpose A variety of soft tissue surgical procedures have been developed for treatment of scapholunate (SL) dissociation. The purpose of this study was to compare the degree of correction obtained (as measured on preoperative and postoperative radiographs) when performing the modified Brunelli technique (MBT) with that of the more commonly performed Blatt capsulodesis (BC) and to evaluate each technique after simulated wrist motion. Methods Five cadaver wrists were used for this study. The SL interval, SL angle, and radiolunate angle were recorded radiographically, with the SL ligament intact, for each wrist in several loaded positions: neutral, flexion, extension, radial deviation, ulnar deviation, and clenched fist. The SL interosseous ligament was then completely incised, and the radiographic measurements were repeated to demonstrate SL instability. The radiographic measurements were then repeated after MBT reconstruction and after BC reconstruction. Additional radiographic measurements were taken after simulated wrist motion. Results Sectioning of the SL ligament resulted in radiographic evidence of SL dissociation. Use of the MBT demonstrated improved correction of the SL interval and the SL angle in the clenched fist position, which was statistically significant when compared with BC. The correction for the SL angle was maintained on the MBT specimens with simulated wrist motion. Conclusions The results demonstrate that in this cadaver model, the MBT better restores the normal carpal relationship of the SL interval and SL angle when compared to the BC, as measured on radiographs. This correction might correlate with improved carpal dynamics and improved clinical outcomes. (J Hand Surg 2010;35A:1589–1598. © 2010 Published by Elsevier Inc. on behalf of the American Society for Surgery of the Hand.) Key words Blatt capsulodesis, modified Brunelli technique, scapholunate dissociation, scapholunate advanced collapse (SLAC) wrist.
From the William Beaumont Army Medical Center, Department of Orthopaedics, El Paso, TX; Walter Reed National Military Medical Center, Integrated Department of Orthopaedics and Rehabilitation, Washington, DC, and Bethesda, MD, The Curtis National Hand Center, Union Memorial Hospital, Baltimore, MD.
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
Received for publication February 5, 2010; accepted in revised form June 24, 2010.
Corresponding author: Ryan Sieg, MD, William Beaumont Army Medical Center, Department of Orthopaedics, 5005 N. Piedras St., El Paso, TX 79920; e-mail: [email protected].
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of Defense or the United States government.
This study was funded by a grant from the Raymond M. Curtis Research Foundation, The Curtis National Hand Center, Union Memorial Hospital, Baltimore, MD.
0363-5023/10/35A10-0003$36.00/0 doi:10.1016/j.jhsa.2010.06.029
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weakness are common complaints of patients presenting to emergency rooms and orthopedic clinics. A substantial portion of these patients will have carpal instability, the most common being scapholunate (SL) dissociation.1 Untreated, SL dissociation has been associated with degenerative changes of the wrist.2 Patients with chronic SL dissociation treated nonsurgically often do poorly and might eventually require surgical management.3 Hence, the goal of surgery is to restore normal mechanics of the wrist in order to relieve pain, restore function, and minimize the chance of the wrist developing degenerative arthritis progressing to an SL advanced collapse pattern. The optimal surgical treatment of chronic SL instability with an irreparable SL interosseous ligament (SLIL) without osteoarthritis is yet to be determined. Intercarpal arthrodesis is associated with low fusion rates, decreased range of motion, and altered joint contact stresses, which potentially leads to arthritis.4 – 6 Soft tissue procedures have the theoretical advantage of preserving intercarpal motion; however, their ability to restore the normal carpal relationship in order to prevent degenerative arthritis is not certain. Many reconstructive procedures have been described in the literature. Some of the techniques used today include repair of the SLIL, screw reduction, debridement, capsulodesis, tenodesis, bone-tissue-bone fixation, and combinations thereof.7–15 The single most common surgical procedure performed for chronic SL instability with an irreparable SLIL without osteoarthritis in the United States and Canada is the Blatt capsulodesis (BC).16 In 1987, Blatt described a dorsal capsulodesis to correct the excessive scaphoid flexion associated with SL dissociation.17 This technique creates a tether from the dorsal rim of the radius to the distal scaphoid in order to limit scaphoid flexion, but it does not address the primary stabilizer, the SLIL.18 Blatt initially reported good results and the elimination of symptoms, allowing patients to return to sports. However, after surgery, radiographs often do not show restoration of normal anatomy and with time, patients who have dorsal capsulodesis might develop arthritic changes due to the inability to maintain the normal carpal relationship.19 –23 Although some patients with these changes seem to be asymptomatic, other patients go on to develop SL advanced collapse wrist arthritis, which might require further surgery. The long-term (⬎10 y) incidence of this phenomenon is not well known. In 1995, Brunelli described a surgical technique using a slip of the flexor carpi radialis (FCR) tendon to
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RIST PAIN AND
provide SL stability.24 Scaphoid flexion is corrected by routing the FCR tendon through the distal volar surface of the scaphoid and securing it to the dorsal and ulnar aspects of the radius, thus addressing both distal and volar secondary stabilizing ligaments, as well as the SLIL. Van Den Abbeele, Talwaker, and Garcia-Elias modified the procedure to avoid the tenodesis crossing the radiocarpal joint by attaching the FCR tendon to the dorsal pole of the lunate as well as looping it around the radiolunotriquetral ligament and suturing the tendon back onto itself.25–27 This modification has been referred to as the modified Brunelli technique (MBT). Early clinical results for these techniques were also comparable with those reported for dorsal capsulodesis with regard to pain relief, grip strength, and range of motion.28 There are few studies evaluating the ability of the MBT to correct and maintain carpal alignment.28 –31 To our knowledge, there have been no cadaveric studies directly comparing the MBT to the BC. The purpose of this study was to evaluate the degree of correction obtained (as measured on preoperative and postoperative radiographs) for SL dissociation when performing the modified Brunelli tenodesis compared to the more commonly performed BC in a cadaveric model. MATERIALS AND METHODS Five cadaveric upper extremities without physical examination findings or radiographic evidence of injury, instability, or degenerative changes were obtained and stored at ⫺4°C until the time of testing. The specimens were thawed at room temperature and disarticulated at the elbow joint, preserving the proximal radioulnar joint. Midline forearm volar and dorsal incisions with skin flaps were created to expose the 3 wrist extensor tendons, 2 wrist flexor tendons, and 8 finger flexor tendons. Half of the FCR tendon was transected proximally and split longitudinally, thus allowing one half of the tendon to provide tension with its normal insertion and the other half to be used later for the MBT. The skin flaps were closed, covering the tendons in the distal forearm. Number 5 Ethibond sutures (Ethicon, Inc., Somerville, NJ) were secured to the exposed tendons proximally, including the intact half of the FCR tendon, using an interlocking grasping suture technique. The forearm was then mounted on a plywood stand in a vertical orientation. Longitudinal 5-mm pins were placed in the proximal ulna and radius. An additional, transverse 5-mm pin was placed in the distal radius. Threaded pins were drilled into the plywood stand, and
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FIGURE 2: A PA radiograph of a neutral wrist.
FIGURE 1: Example of weight suspension for loading conditions.
an external fixator frame was constructed to connect the forearm to the plywood stand. Small, metal S-shaped hooks were then connected to the number 5 Ethibond suture (Ethicon, Inc.) and prepared to suspend weights to simulate different wrist positions according to Slater (Fig. 1).32,33 The amount of weight was the same for all specimens and achieved the desired wrist positions in each instance. The degree of motion achieved varied slightly between specimens, depending on the cadaver wrist and soft tissues. With the loads applied, each wrist reached the maximum excursion that could be achieved in the desired wrist direction. Wrist flexion was created with 5 lb weights applied to both the FCR and the flexor carpi ulnaris tendons. Wrist extension was created with 5 lb of weight on the extensor carpi ulnaris tendon and 5 lb on the combined extensor carpi radialis brevis and longus tendons. Ulnar deviation was created with 5 lb on both the flexor and extensor carpi ulnaris tendons. Radial deviation was created with 5 lb on the FCR and 5 lb on the combined extensor carpi radialis brevis and longus tendons. A clenched fist was simulated with a 20-lb
weight applied to the flexor digitorum superficialis and profundus tendons with the wrist positioned in 20° of extension, confirmed by a goniometer. All 8 finger flexors were sutured side-to-side in order to load them equally. Radiographs were obtained using the Fluoroscan III Imaging System C-Arm (Model #50700; Fluoroscan Imaging Systems, Inc., Northbrook, IL). The miniature c-arm was positioned to obtain standardized posteroanterior (PA) images of the wrist, as reported previously in the literature (Fig. 2).34 Radiographic images were then obtained with the intact wrist in neutral, flexion, extension, ulnar deviation, radial deviation, and the clenched fist position. This condition is referred to as intact. The floor was marked with tape to the position of the plywood frame. The frame was rotated 90° to obtain standard lateral radiographs of the wrist without moving the Fluoroscan.35 When the lateral images were properly aligned, the floor was again marked, and radiographs were obtained in similar wrist positions. We then surgically created SL instability through a dorsal capsulotomy, using 2.5⫻ magnification surgical loupes to improve visualization. This was done by opening the third dorsal wrist compartment, elevating the extensor retinaculum, and creating a 1-cm-wide dorsal capsular flap, centered over the SL interval. This capsular flap was later used for the BC reconstruction. The remainder of the dorsal capsule was elevated, sparing the dorsal intercarpal ligament and the dorsal radiotriquetral ligament. This exposed the necessary carpals and SLIL, which was transected sharply using a number 15 scalpel blade followed by division of the volar radioscaphocapitate ligament to create SL dissociation. According to Short et al.,18 the SLIL is the
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primary stabilizer of the SL articulation and the radioscaphocapitate ligament is a secondary stabilizer. After sectioning both ligaments, we found the scaphoid to be unstable, with grossly increased mobility. The dorsal capsular flap and the remainder of the dorsal capsule were closed using interrupted 2-0 Ethibond sutures, followed by closure of the extensor retinaculum and skin. This condition, which is referred to as cut, then had radiographic imaging in both the PA and lateral radiographic views in all wrist positions, using the loading conditions described earlier. The first surgical stabilization procedure to be performed on the unstable specimen was determined by the toss of a coin, resulting in the MBT being performed initially. The MBT was performed as described in the literature.28 The volar skin was reopened, exposing the distally attached FCR tendon slip. Removing the previous skin, retinaculum, and capsule sutures exposed the dorsal scaphoid. A K-wire was then drilled through the dorsal bare area on the scaphoid and exited the volar distal pole of the scaphoid. A cannulated 3.2-mm drill was then used to drill through the scaphoid. The FCR tendon slip was then passed from the volar surface through the scaphoid, exiting dorsally. A 3.5-mm TwinFix suture anchor with number 2 DuraBraid suture (Smith & Nephew, London, UK) was then placed into the lunate, positioned at the lunate insertion of the SL ligament. The FCR tendon slip was passed dorsally across the lunate and looped around the radiotriquetral ligament. The scaphoid and lunate were reduced by manual manipulation while we simultaneously tensioned the FCR tendon slip until the joint surfaces matched the anatomic alignment before ligament sectioning, as judged by the surgeon. Once the SL interval was reduced, the FCR tendon slip was sutured to the dorsal surface of the lunate, using the suture from the suture anchor. The FCR was further secured by suturing the free end of the tendon slip back to itself on the dorsum of the lunate. The dorsal capsule, extensor retinaculum, and both volar and dorsal skin incisions were closed. Next, the specimen was again secured to the plywood using the external fixator, and radiographic imaging was obtained. The specimen was then removed from the frame, the Brunelli reconstruction was taken down, and the BC was performed, as described in the literature.17 A similar 3.5-mm TwinFix suture anchor (Smith & Nephew) was placed in the dorsal scaphoid distal to the axis of rotation and 3 mm from the scaphotrapezio-trapezoidal joint. The scaphoid and lunate were reduced by manual manipulation until the joint surfaces matched the anatomic alignment before ligament sectioning. The 1-cm-
FIGURE 3: An SL interval measurement on a PA radiograph. Reprinted with permission from Green’s Operative Hand Surgery, 5th ed., Vol. 1, Garcia-Elias M, Geissler WB, Carpal instability, pp. 535– 604, Copyright Elsevier, 2005.
wide dorsal capsular flap was secured to the distal dorsal scaphoid, using the suture anchor. Suturing the free capsule tissue margins to the 3 sides of the 1-cmwide capsule flap closed the dorsal capsule. The extensor retinaculum and skin were closed with sutures, the specimen was again secured to the frame, and radiographic imaging was performed. Each subsequent specimen was chosen from the supply of cadaver extremities in a random order and tested in a similar manner. The order of the procedures alternated. The second and fourth specimens started with BC, and the third and fifth specimens started with the MBT. The second surgical reconstruction procedure was left intact in each specimen, leaving 3 with the BC and 2 with the MBT, in order to evaluate the durability of each procedure after simulated wrist motion. Each wrist was carefully cycled manually by the senior author (P.J.P.) from flexion to extension, reaching the extent of the soft tissue constraints through 100 repetitions, and imaging was repeated. We chose 100 cycles to allow adequate creep of the soft tissues and to likely reach a stable final end state of the reconstructive procedures. After completion of testing on all 5 specimens, the digital images were downloaded to a computer software program (Adobe Photoshop 6.0; Adobe Systems Inc., San Jose, CA) to measure the SL interval and both the SL and the radiolunate (RL) angles. The SL interval was measured on PA radiographs as the distance between the midpoint of the scaphoid and the lunate (Fig. 3). A 4.54-cm-long K-wire, measured by a commercially available digital caliper (Small Mode SPI 2000
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FIGURE 4: Carpal angle determination. This figure demonstrates 3 illustrated lateral radiographic views of the wrist carpals. A Line “S” represents a parallel line drawn along the volar surface of the scaphoid. B Line “L” represents a line drawn perpendicular to the 2 distal poles of the lunate. C Line “R” represents a line drawn parallel to the medullary canal of the radius. Reprinted with permissin from Green’s Operative Hand Surgery, 5th ed., Vol. 1, Garcia-Elias M, Geissler WB, Carpal instability, pp. 535– 604, Copyright Elsevier, 2005.
31– 415–3; Mitutoyo, Aurora, IL) was included in the PA radiographs of all specimens to calibrate length measurements, eliminating the effect of magnification to improve assessment of the SL interval. The wire was placed by hand transversely, just proximal to the carpal bones on the volar surface of the radius. The length of the wire was measured by the software program and recorded to the same degree of accuracy as the caliper. The SL interval was measured as recommended by Kindynis, using the software program.36 The true SL interval was then calculated by using the conversion factor derived from the known length of the wire to correct for magnification. The SL angle was measured on lateral radiographs using the volar surface of the scaphoid and a perpendicular line drawn from the 2 distal poles of the lunate (Fig. 4).35 The RL angle was measured according to the line drawn perpendicular to the 2 distal poles of the lunate and a line parallel to the medullary canal of the radius (Fig. 4).35 An independent power analysis on SL interval indicated that a sample size of 5 would allow an 80% chance of detecting a 30% change at the .05 probability level, assuming a standard deviation in SL interval size of 0.5 mm. The statistical analysis was performed using a repeated-measure analysis of variance, with significance set at p⬍.05. This analysis allowed each of the 5 intact specimens to act as the control for the subsequent measurements on the same cadaver specimen. To determine which of the 4 different conditions (intact, cut, MBT, BC) were significantly different from the rest, a range of nonsignificance was determined using a Tukey
test with significance set at p⬍.05. The cycled specimens were analyzed separately. The magnitude of change from precycling to postcycling was determined for both the MBT and BC specimens and compared using Student’s t-test with significance set at p⬍.05. RESULTS Scapholunate interval The SL interval increased in all wrist positions after SL dissociation was surgically created. This was statistically significant (p⬍.05) with the wrist in flexion, radial deviation, and the clenched fist position. The clenched fist position demonstrated the greatest increase, from 2.9 ⫾ 0.6 mm (mean ⫾ SD) when the ligaments were intact to 5.0 ⫾ 0.3 mm when the ligaments were sectioned. The clenched fist radiograph maximally stresses the SL ligament and has been shown in the literature to best evaluate SL instability.37 The first row of Table 1 summarizes the SL interval obtained for all 4 conditions (intact, cut, MBT, BC) of the SL ligaments with the wrist in the clenched fist position and the additional change in SL interval with cycling. Surgical reconstruction using the MBT better restored the normal SL interval than did the BC (Fig. 5). After the MBT, there were no significant differences in the SL interval when compared to the intact specimens in any wrist position. After the BC, the SL interval remained significantly increased (p⬍.05) compared with the intact specimens when the wrist was placed in the clenched fist position. There were no significant
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TABLE 1. Average SL Interval in the Clenched Fist Position, Average SL Angle in the Clenched Fist Position, and Average RL Angle in Radial Deviation for All Wrist Conditions of the SL Ligaments
1. Scapholunate interval in the clenched fist position (mean ⫾ SD; mm)
Intact
Cut
MBT
BC
2.9 ⫾ 0.6
5.0 ⫾ 0.3*
2.6 ⫾ 0.6
4.6 ⫾ 0.4*
2. Scapholunate angle in the clenched 54.8 ⫾ 6.1 70.5 ⫾ 3.4* 58.8 ⫾ 3.1 67.2 ⫾ 3.7* fist position (mean ⫾ SD; °) 4.0 ⫾ 1.6 16.3 ⫾ 7.1*
3. Radiolunate angle in radial deviation (mean ⫾ SD; °)
9.2 ⫾ 2.1
6.4 ⫾ 6.3
MBT Change With BC Change With Cycling (n⫽2) Cycling (n⫽3) 0.3 ⫾ 0.4
0.3 ⫾ 0.5
⫺0.6 ⫾ 1.1†
3.3 ⫾ 0.7†
6.0 ⫾ 2.8
0.7 ⫾ 3.5
*Denotes statistically significant difference from the intact state. †Denotes statistically significant difference between MBT and BC for cycled specimens.
6 5 neutral 4
flexion extension
3
radial ulnar
2
fist 1 0 Intact
Cut
MBT
BC
MBT Cycled
BC Cycled
FIGURE 5: Average SL interval for all conditions and positions (mm).
differences in the SL interval when compared to the intact specimens for the other wrist positions after BC. In addition to comparing the intact group with each reconstructed group, comparisons were made between the 2 reconstructed groups. In the clenched fist position, there was a significant increase in the SL interval measured after BC compared with MBT (4.6 ⫾ 0.4 mm vs 2.6 ⫾ 0.6 mm, respectively; p⬍.05). No significant differences were noted with the other wrist positions. After simulated wrist motion, there were no significant differences in the magnitude of change from precycling to postcycling in the 2 MBT cycled specimens or in the 3 BC specimens. Scapholunate angle The SL angle demonstrated increased values in all wrist positions after SL dissociation was surgically created. This was statistically significant (p⬍.05) with the wrist in radial deviation and in the clenched fist position. The
clenched fist position demonstrated the greatest increase, from 54.8° ⫾ 6.1° when the ligaments were intact to 70.5° ⫾ 3.4° when the ligaments were sectioned. The second row of Table 1 summarizes the SL angle obtained for all 4 conditions (intact, cut, MBT, BC) of the SL ligaments with the wrist in the clenched fist position and the additional change in SL angle with cycling. Surgical reconstruction using the MBT better restored the normal SL angle than did the BC (Fig. 6). After the MBT, there were no significant differences in the SL angle when compared to the intact specimens in any wrist position. After the BC, the SL angle remained statistically increased (p⬍.05) compared with the intact specimens when the wrist was placed in flexion and in the clenched fist position. There were no significant differences in the SL angle when compared to the intact specimens for the other wrist positions after BC. There was a statistically significant increase in the SL angle measured after BC compared with the MBT in
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90 80 70
neutral
60
flexion
50
extension
40
radial
30
ulnar
20
fist
10 0 Intact
Cut
MBT
BC
MBT Cycled
BC Cycled
FIGURE 6: Average SL angle for all wrist conditions and positions (°).
RL angle 50 40 neutral
30
flexion
20
extension
Extension 10
radial ulnar
0
Flexion 10
fist
Intact
Cut
MBT
BC
MBT Cycled
BC Cycled
20 FIGURE 7: Average RL angle for all wrist conditions and positions (°).
the clenched fist position (67.2° ⫾ 3.7° vs 58.8° ⫾ 3.1°, respectively; p⬍.05) and flexion (80.7° ⫾ 2.3° vs 64.9° ⫾ 4.9°, respectively; p⬍.05). After simulated wrist motion, there was a significant difference in the magnitude of change from precycling to postcycling between the MBT and BC in the clenched fist position (p⫽.016). On average, the SL angle for the 2 cycled MBT specimens changed by ⫺0.6 ⫾ 1.1 mm and the 3 BC specimens changed by 3.3 ⫾ 0.7 mm (Table 1). Radiolunate angle As expected, after SL dissociation was surgically created, the RL angle demonstrated increases in lunate extension with most wrist positions except extension and the clenched fist position. Both of these wrist po-
sitions result in extension of the entire carpus in relationship to the radius, which naturally extends the lunate and possibly matches or surpasses the magnitude of abnormal lunate extension seen with SL dissociation. Only with the wrist in radial deviation was the increased lunate extension statistically significant, increasing from 4.0° ⫾ 1.6° when the ligaments were intact to 16.3° ⫾ 7.1° when the ligaments were sectioned (p⬍.05). The third row in Table 1 summarizes the RL angle obtained for all 4 conditions (intact, cut, MBT, BC) of the SL ligaments with the wrist in radial deviation and the additional change in RL angle with cycling. After surgical reconstruction, both the MBT and the BC demonstrated no statistically significant differences in RL angle when compared to the intact specimens.
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Figure 7 shows the average RL angles for all wrist conditions of the SL ligaments and loading positions. With the wrist in radial deviation, the MBT corrected the RL angle to a final value of 9.2° ⫾ 2.1°, whereas the BC corrected the RL angle to a final value of 6.4° ⫾ 6.3°. There was no statistically significant difference for the amount of RL angle correction with the wrist in radial deviation when comparing the 2 procedures. After simulated wrist motion, there were no significant differences in the magnitude of change from precycling to postcycling between the MBT and the BC for any wrist position. DISCUSSION Since Blatt first described the dorsal capsulodesis in 1987, numerous treatments have been developed, and continue to be developed, for SL dissociation, suggesting persistent disappointment with current outcomes from the described surgical procedures. The BC is still commonly performed. One intuitive criticism of the BC is that the reconstruction is nonanatomic. Reconstructing the ligamentous anatomy to restore the normal carpal relationships would be expected to result in normal forces being distributed to the articular surfaces of the carpals, relieving pain, preventing degenerative changes, and restoring wrist function. The commonly performed BC is a soft tissue procedure that attempts to preserve the majority of wrist motion. The associated loss of wrist flexion is believed to be secondary to the dorsal tether of the scaphoid to the radius. The MBT has the theoretical advantage of a more anatomic correction of SL dissociation. The FCR tendon slip is attached distally and volarly at its normal insertion on the index metacarpal. This prevents the distal pole of the scaphoid from flexing by reconstructing or reinforcing the volar ligaments, which are thought to be secondary stabilizers that are injured or lax. This FCR tendon slip is passed through the body of the scaphoid, exits the dorsum of the proximal scaphoid, and is secured to the dorsal lunate, reconstructing the normal anatomy of the dorsal SLIL. The FCR tendon slip is tensioned, using the distal portion of the dorsal radiotriquetral ligament to act as a pulley and reduce the SL interval, by pulling the proximal scaphoid ulnarly toward the lunate. Although this part of the modified procedure is not anatomic, looping the FCR slip around the dorsal radiotriquetral ligament does effectively reattach the lunate to the dorsal radiotriquetral ligament, which is normal. The abnormal lunate extension is corrected under direct visualization and theoretically held in place by the reconstructed dorsal SL ligament.
In our study, BC poorly corrected the SL interval and angle after SL dissociation and demonstrated an increase in SL angle after simulated wrist motion compared to MBT. The MBT better corrected the SL interval and angle and maintained the SL angle after wrist motion. The difference in correction of the RL angle between the 2 procedures did not reach statistical significance. The number of specimens in the cycled groups consisted of only 2 specimens in the MBT group and 3 specimens in the BC group. There was a trend toward increased lunate extension after cycling the MBT specimens in several wrist positions. Perhaps the FCR tendon, which is secured to the dorsal lunate and distal to the axis of rotation for lunate flexion and extension, has a tendency to hyperextend the lunate. If this does occur in vivo, it could result in abnormal articulation between the lunate and capitate and proceed with degenerative changes similar to those seen with SL advanced collapse. Previous authors have reported the radiographic outcomes of both the BC and the MBT clinically and in cadaveric models. Moran et al.19 retrospectively evaluated the BC in 11 patients. Initial postoperative radiographs demonstrated a decrease in the SL interval and angle, but after an average follow-up evaluation of 54 months, the correction of both was lost. Slater et al.32 evaluated the BC radiographically in a cadaveric model. After surgical correction, the BC failed to restore the SL interval (p⬍.05). Links et al.31 retrospectively evaluated 21 patients who received the MBT, after an average follow-up of 29 months. When compared to preoperative radiographs, there was an average 15° ⫾ 5° decrease in the SL angle and 1.6 ⫾ 0.8 mm decrease in the SL interval. Moran et al.28 retrospectively analyzed 15 patients who had surgical reconstruction for chronic SL instability using the MBT, at an average follow-up of 36 months. When compared to preoperative radiographs, the SL angle correction was maintained and found to be statistically significant (p⫽.04). Both of these studies suggest that the MBT corrects and maintains the normal carpal relationship for a minimum of 3 years. However, in a retrospective analysis of 19 patients with a mean follow-up of 37 months after MBT, Chabas et al.30 reported a loss of the SL angle correction that was present immediately after surgery. Thus, there are conflicting data for the efficacy of the MBT to maintain carpal anatomy. To our knowledge, only one cadaveric study has been performed to evaluate the radiographic outcomes of the MBT. In 2008, Howlett et al.38 compared distal-
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exiting scaphoid tunnel placement with proximalexiting tunnel placement using Mersilene tape (Ethicon, Inc., Somerville, NJ) in place of the FCR tendon. After surgical reconstruction, the SL angle decreased to within 15° ⫾ 10° of the mean intact specimen for the proximal tunnel and 4° ⫾ 7° for the distal tunnel. This difference was statistically significant (p⬍.05) in favor of distal tunnel placement. The SL interval significantly decreased (p⬍.05) for both groups when compared to the intact specimen; however, there was no statistical difference between the 2 groups when comparing the 2 tunnel placements alone. Limitations of this study include the use of Mersilene tape (Ethicon, Inc.), which, according to Howlett, is stiffer than tendon and does not accurately represent an in vivo model. In addition, there were no measurements after simulated wrist motion to evaluate the ability to maintain correction. This study has several limitations. The specimens are cadavers and do not allow healing of tissue to provide more durable reconstructions, especially tendon healing to bone. The correlation between radiographic measurements and clinical outcomes—such as pain relief, wrist motion, and grip strength—is not known. Also, assumptions cannot be made on long-term clinical outcomes as they relate to radiographic measurements and degenerative changes. The static PA and lateral radiographs measuring 3 carpal relationships does not fully evaluate the static and dynamic relationship of the carpal bones, which Berdia described as being a complex relationship that depends on wrist position and the direction of wrist motion.39 Although there was a statistically significant difference in the magnitude of change of the SL angle between the MBT and BC for the cycled specimens, only a small number of specimens were used for this part of the investigation. Additional studies are required to evaluate the durability of these reconstructive procedures. The MBT prevents scaphoid flexion by 2 points of fixation with a distal volar buttress and proximal dorsal tether. The SL interval is directly reduced by ulnarly directed tension on the proximal scaphoid, recreating the dorsal SL ligament. This results in greater corrections of both the SL interval and the SL angle, and it better withstands simulated wrist motion when compared to the BC. The BC tethers the scaphoid distally to prevent flexion, but it does not secure the proximal scaphoid. The SL interval is reduced after the BC indirectly, as scaphoid flexion is corrected. The improved radiographic measurements observed with the MBT imply improved anatomic restoration in cadavers and potentially improved clinical outcomes in patients. Further long-term clinical studies to compare radio-
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graphic correction, degenerative changes, and patient outcomes are needed to determine the optimal surgical treatment for chronic SL instability. REFERENCES 1. Jones WA. Beware the sprained wrist. The incidence and diagnosis of scapholunate instability. J Bone Joint Surg 1988;70B:293–297. 2. Watson HK, Ballet FL. The SLAC wrist: scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg 1984;9A:358 – 365. 3. Stanley JK, Trail IA. Carpal instability. J Bone Joint Surg 1994;76B: 691–700. 4. Hom S, Ruby LK. Attempted scapholunate arthrodesis for chronic scapholunate dissociation. J Hand Surg 1991;16A:334 –339. 5. Augsburger S, Necking L, Horton J, Bach AW, Tencer AF. A comparison of scaphoid-trapezium-trapezoid fusion and four-bone tendon weave for scapholunate dissociation. J Hand Surg 1992; 17A:360 –369. 6. Garcia-Elias M, Cooney WP, An KN, Linscheid RL, Chao EY. Wrist kinematics after limited intercarpal arthrodesis. J Hand Surg 1989; 14A:791–799. 7. Bleuler P, Shafighi M, Donati OF, Gurunluoglu R, Constantinescu MA. Dynamic repair of scapholunate dissociation with dorsal extensor carpi radialis longus tenodesis. J Hand Surg 2008;33A:281–284. 8. Opreanu RC, Baulch M, Katranji A. Reduction and maintenance of scapholunate dissociation using the TwinFix screw. Eplasty 2009;9:e7. Epub 2009 Jan 29. 9. Szabo RM. Scapholunate ligament repair with capsulodesis reinforcement. J Hand Surg 2008;33A:1645–1654. 10. Harvey EJ, Berger RA, Osterman AL, Fernandez DL, Weiss AP. Bone-tissue-bone repairs for scapholunate dissociation. J Hand Surg 2007;32A:256 –264. 11. Minami A, Kato H, Iwasaki N. Treatment of scapholunate dissociation: ligamentous repair associated with modified dorsal capsulodesis. Hand Surg 2003;8:1– 6. 12. Schweizer A, Steiger R. Long-term results after repair and augmentation ligamentoplasty of rotatory subluxation of the scaphoid. J Hand Surg 2002;27A:674 – 684. 13. Szabo RM, Slater RR Jr, Palumbo CF, Gerlach T. Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: clinical results. J Hand Surg 2002;27A:978 –984. 14. Dunn MJ, Johnson C. Static scapholunate dissociation: a new reconstruction technique using a volar and dorsal approach in a cadaver model. J Hand Surg 2001;26A:749 –754. 15. Short WH, Werner FW, Sutton LG. Treatment of scapholunate dissociation with a bioresorbable polymer plate: a biomechanical study. J Hand Surg 2008;33A:643– 649. 16. Zarkadas PC, Gropper PT, White NJ, Perey BH. A survey of the surgical management of acute and chronic scapholunate instability. J Hand Surg 2004;29A:848 – 857. 17. Blatt G. Capsulodesis in reconstructive hand surgery. Dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna. Hand Clin 1987;3:81–102. 18. Short WH, Werner FW, Green JK, Masaoka S. Biomechanical evaluation of ligamentous stabilizers of the scaphoid and lunate: part II. J Hand Surg 2005;30A:24 –34. 19. Moran SL, Cooney WP, Berger RA, Strickland J. Capsulodesis for the treatment of chronic scapholunate instability. J Hand Surg 2005; 30A:16 –23. 20. Pomerance J. Outcome after repair of the scapholunate interosseous ligament and dorsal capsulodesis for dynamic scapholunate instability due to trauma. J Hand Surg 2006;31A:1380 –1386. 21. Deshmukh SC, Givissis P, Belloso D, Stanley JK, Trail IA. Blatt’s capsulodesis for chronic scapholunate dissociation. J Hand Surg 1999;24B:215–220.
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22. Muermans S, De Smet L, Van Ransbeeck H. Blatt dorsal capsulodesis for scapholunate instability. Acta Orthop Belg 1999;65:434 – 439. 23. Gajendran VK, Peterson B, Slater RR Jr, Szabo RM. Long-term outcomes of dorsal intercarpal ligament capsulodesis for chronic scapholunate dissociation. J Hand Surg 2007;32A:1323–1333. 24. Brunelli GA, Brunelli GR. A new technique to correct carpal instability with scaphoid rotary subluxation: a preliminary report. J Hand Surg 1995;20A:S82–S85. 25. Van Den Abbeele KL, Loh YC, Stanley JK, Trail IA. Early results of a modified Brunelli procedure for scapholunate instability. J Hand Surg 1998;23B:258 –261. 26. Talwalkar SC, Edwards AT, Hayton MJ, Stilwell JH, Trail IA, Stanley JK. Results of tri-ligament tenodesis: a modified Brunelli procedure in the management of scapholunate instability. J Hand Surg 2006;31B:110 –117. Epub 2005 Nov 15. 27. Garcia-Elias M, Lluch AL, Stanley JK. Three-ligament tenodesis for the treatment of scapholunate dissociation: indications and surgical technique. J Hand Surg 2006;31A:125–134. 28. Moran SL, Ford KS, Wulf CA, Cooney WP. Outcomes of dorsal capsulodesis and tenodesis for treatment of scapholunate instability. J Hand Surg 2006;31A:1438 –1446. 29. De Smet L, Van Hoonacker P. Treatment of chronic static scapholunate dissociation with the modified Brunelli technique: preliminary results. Acta Orthop Belg 2007;73:188 –191. 30. Chabas JF, Gay A, Valenti D, Guinard D, Legre R. Results of the modified Brunelli tenodesis for treatment of scapholunate instability: a retrospective study of 19 patients. J Hand Surg 2008;33A:1469 –1477.
31. Links AC, Chin SH, Waitayawinyu T, Trumble TE. Scapholunate interosseous ligament reconstruction: results with a modified Brunelli technique versus four-bone weave. J Hand Surg 2008;33A:850 – 856. 32. Slater RR Jr, Szabo RM, Bay BK, Laubach J. Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model. J Hand Surg 1999;24A:232–239. 33. Brand PW, Beach RB, Thompson DE. Relative tension and potential excursion of muscles in the forearm and hand. J Hand Surg 1981; 6A:209 –219. 34. Schuind FA, Linscheid RL, An KN, Chao EY. A normal data base of posteroanterior roentgenographic measurements of the wrist. J Bone Joint Surg 1992;74A:1418 –1429. 35. Larsen CF, Mathiesen FK, Lindequist S. Measurements of carpal bone angles on lateral wrist radiographs. J Hand Surg 1991;16A: 888 – 893. 36. Kindynis P, Resnick D, Kang HS, Haller J, Sartoris DJ. Demonstration of the scapholunate space with radiography. Radiology 1990; 175:278 –280. 37. Lawand A, Foulkes GD. The “clenched pencil” view: a modified clenched fist scapholunate stress view. J Hand Surg 2003;28A:414 – 418. 38. Howlett JP, Pfaeffle HJ, Waitayawinyu T, Trumble TE. Distal tunnel placement improves scaphoid flexion with the Brunelli tenodesis procedure for scapholunate dissociation. J Hand Surg 2008;33A: 1756 –1764. 39. Berdia S, Short WH, Werner FW, Green JK, Panjabi M. The hysteresis effect in carpal kinematics. J Hand Surg 2006;31A:594 – 600.
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Radiographic Evaluation of the Modified Brunelli Technique Versus the Blatt Capsulodesis for Scapholunate Dissociation in a Cadaver Model Patrick J. Pollock, MD, Ryan N. Sieg, MD, Martin F. Baechler, MD, Danielle Scher, MD, Neal B. Zimmerman, MD, Norman H. Dubin, PhD
Purpose A variety of soft tissue surgical procedures have been developed for treatment of scapholunate (SL) dissociation. The purpose of this study was to compare the degree of correction obtained (as measured on preoperative and postoperative radiographs) when performing the modified Brunelli technique (MBT) with that of the more commonly performed Blatt capsulodesis (BC) and to evaluate each technique after simulated wrist motion. Methods Five cadaver wrists were used for this study. The SL interval, SL angle, and radiolunate angle were recorded radiographically, with the SL ligament intact, for each wrist in several loaded positions: neutral, flexion, extension, radial deviation, ulnar deviation, and clenched fist. The SL interosseous ligament was then completely incised, and the radiographic measurements were repeated to demonstrate SL instability. The radiographic measurements were then repeated after MBT reconstruction and after BC reconstruction. Additional radiographic measurements were taken after simulated wrist motion. Results Sectioning of the SL ligament resulted in radiographic evidence of SL dissociation. Use of the MBT demonstrated improved correction of the SL interval and the SL angle in the clenched fist position, which was statistically significant when compared with BC. The correction for the SL angle was maintained on the MBT specimens with simulated wrist motion. Conclusions The results demonstrate that in this cadaver model, the MBT better restores the normal carpal relationship of the SL interval and SL angle when compared to the BC, as measured on radiographs. This correction might correlate with improved carpal dynamics and improved clinical outcomes. (J Hand Surg 2010;35A:1589–1598. © 2010 Published by Elsevier Inc. on behalf of the American Society for Surgery of the Hand.) Key words Blatt capsulodesis, modified Brunelli technique, scapholunate dissociation, scapholunate advanced collapse (SLAC) wrist.
From the William Beaumont Army Medical Center, Department of Orthopaedics, El Paso, TX; Walter Reed National Military Medical Center, Integrated Department of Orthopaedics and Rehabilitation, Washington, DC, and Bethesda, MD, The Curtis National Hand Center, Union Memorial Hospital, Baltimore, MD.
No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
Received for publication February 5, 2010; accepted in revised form June 24, 2010.
Corresponding author: Ryan Sieg, MD, William Beaumont Army Medical Center, Department of Orthopaedics, 5005 N. Piedras St., El Paso, TX 79920; e-mail: [email protected].
The opinions or assertions contained herein are the private views of the authors and are not to be construed as official or reflecting the views of the Department of Defense or the United States government.
This study was funded by a grant from the Raymond M. Curtis Research Foundation, The Curtis National Hand Center, Union Memorial Hospital, Baltimore, MD.
0363-5023/10/35A10-0003$36.00/0 doi:10.1016/j.jhsa.2010.06.029
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weakness are common complaints of patients presenting to emergency rooms and orthopedic clinics. A substantial portion of these patients will have carpal instability, the most common being scapholunate (SL) dissociation.1 Untreated, SL dissociation has been associated with degenerative changes of the wrist.2 Patients with chronic SL dissociation treated nonsurgically often do poorly and might eventually require surgical management.3 Hence, the goal of surgery is to restore normal mechanics of the wrist in order to relieve pain, restore function, and minimize the chance of the wrist developing degenerative arthritis progressing to an SL advanced collapse pattern. The optimal surgical treatment of chronic SL instability with an irreparable SL interosseous ligament (SLIL) without osteoarthritis is yet to be determined. Intercarpal arthrodesis is associated with low fusion rates, decreased range of motion, and altered joint contact stresses, which potentially leads to arthritis.4 – 6 Soft tissue procedures have the theoretical advantage of preserving intercarpal motion; however, their ability to restore the normal carpal relationship in order to prevent degenerative arthritis is not certain. Many reconstructive procedures have been described in the literature. Some of the techniques used today include repair of the SLIL, screw reduction, debridement, capsulodesis, tenodesis, bone-tissue-bone fixation, and combinations thereof.7–15 The single most common surgical procedure performed for chronic SL instability with an irreparable SLIL without osteoarthritis in the United States and Canada is the Blatt capsulodesis (BC).16 In 1987, Blatt described a dorsal capsulodesis to correct the excessive scaphoid flexion associated with SL dissociation.17 This technique creates a tether from the dorsal rim of the radius to the distal scaphoid in order to limit scaphoid flexion, but it does not address the primary stabilizer, the SLIL.18 Blatt initially reported good results and the elimination of symptoms, allowing patients to return to sports. However, after surgery, radiographs often do not show restoration of normal anatomy and with time, patients who have dorsal capsulodesis might develop arthritic changes due to the inability to maintain the normal carpal relationship.19 –23 Although some patients with these changes seem to be asymptomatic, other patients go on to develop SL advanced collapse wrist arthritis, which might require further surgery. The long-term (⬎10 y) incidence of this phenomenon is not well known. In 1995, Brunelli described a surgical technique using a slip of the flexor carpi radialis (FCR) tendon to
W
RIST PAIN AND
provide SL stability.24 Scaphoid flexion is corrected by routing the FCR tendon through the distal volar surface of the scaphoid and securing it to the dorsal and ulnar aspects of the radius, thus addressing both distal and volar secondary stabilizing ligaments, as well as the SLIL. Van Den Abbeele, Talwaker, and Garcia-Elias modified the procedure to avoid the tenodesis crossing the radiocarpal joint by attaching the FCR tendon to the dorsal pole of the lunate as well as looping it around the radiolunotriquetral ligament and suturing the tendon back onto itself.25–27 This modification has been referred to as the modified Brunelli technique (MBT). Early clinical results for these techniques were also comparable with those reported for dorsal capsulodesis with regard to pain relief, grip strength, and range of motion.28 There are few studies evaluating the ability of the MBT to correct and maintain carpal alignment.28 –31 To our knowledge, there have been no cadaveric studies directly comparing the MBT to the BC. The purpose of this study was to evaluate the degree of correction obtained (as measured on preoperative and postoperative radiographs) for SL dissociation when performing the modified Brunelli tenodesis compared to the more commonly performed BC in a cadaveric model. MATERIALS AND METHODS Five cadaveric upper extremities without physical examination findings or radiographic evidence of injury, instability, or degenerative changes were obtained and stored at ⫺4°C until the time of testing. The specimens were thawed at room temperature and disarticulated at the elbow joint, preserving the proximal radioulnar joint. Midline forearm volar and dorsal incisions with skin flaps were created to expose the 3 wrist extensor tendons, 2 wrist flexor tendons, and 8 finger flexor tendons. Half of the FCR tendon was transected proximally and split longitudinally, thus allowing one half of the tendon to provide tension with its normal insertion and the other half to be used later for the MBT. The skin flaps were closed, covering the tendons in the distal forearm. Number 5 Ethibond sutures (Ethicon, Inc., Somerville, NJ) were secured to the exposed tendons proximally, including the intact half of the FCR tendon, using an interlocking grasping suture technique. The forearm was then mounted on a plywood stand in a vertical orientation. Longitudinal 5-mm pins were placed in the proximal ulna and radius. An additional, transverse 5-mm pin was placed in the distal radius. Threaded pins were drilled into the plywood stand, and
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FIGURE 2: A PA radiograph of a neutral wrist.
FIGURE 1: Example of weight suspension for loading conditions.
an external fixator frame was constructed to connect the forearm to the plywood stand. Small, metal S-shaped hooks were then connected to the number 5 Ethibond suture (Ethicon, Inc.) and prepared to suspend weights to simulate different wrist positions according to Slater (Fig. 1).32,33 The amount of weight was the same for all specimens and achieved the desired wrist positions in each instance. The degree of motion achieved varied slightly between specimens, depending on the cadaver wrist and soft tissues. With the loads applied, each wrist reached the maximum excursion that could be achieved in the desired wrist direction. Wrist flexion was created with 5 lb weights applied to both the FCR and the flexor carpi ulnaris tendons. Wrist extension was created with 5 lb of weight on the extensor carpi ulnaris tendon and 5 lb on the combined extensor carpi radialis brevis and longus tendons. Ulnar deviation was created with 5 lb on both the flexor and extensor carpi ulnaris tendons. Radial deviation was created with 5 lb on the FCR and 5 lb on the combined extensor carpi radialis brevis and longus tendons. A clenched fist was simulated with a 20-lb
weight applied to the flexor digitorum superficialis and profundus tendons with the wrist positioned in 20° of extension, confirmed by a goniometer. All 8 finger flexors were sutured side-to-side in order to load them equally. Radiographs were obtained using the Fluoroscan III Imaging System C-Arm (Model #50700; Fluoroscan Imaging Systems, Inc., Northbrook, IL). The miniature c-arm was positioned to obtain standardized posteroanterior (PA) images of the wrist, as reported previously in the literature (Fig. 2).34 Radiographic images were then obtained with the intact wrist in neutral, flexion, extension, ulnar deviation, radial deviation, and the clenched fist position. This condition is referred to as intact. The floor was marked with tape to the position of the plywood frame. The frame was rotated 90° to obtain standard lateral radiographs of the wrist without moving the Fluoroscan.35 When the lateral images were properly aligned, the floor was again marked, and radiographs were obtained in similar wrist positions. We then surgically created SL instability through a dorsal capsulotomy, using 2.5⫻ magnification surgical loupes to improve visualization. This was done by opening the third dorsal wrist compartment, elevating the extensor retinaculum, and creating a 1-cm-wide dorsal capsular flap, centered over the SL interval. This capsular flap was later used for the BC reconstruction. The remainder of the dorsal capsule was elevated, sparing the dorsal intercarpal ligament and the dorsal radiotriquetral ligament. This exposed the necessary carpals and SLIL, which was transected sharply using a number 15 scalpel blade followed by division of the volar radioscaphocapitate ligament to create SL dissociation. According to Short et al.,18 the SLIL is the
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primary stabilizer of the SL articulation and the radioscaphocapitate ligament is a secondary stabilizer. After sectioning both ligaments, we found the scaphoid to be unstable, with grossly increased mobility. The dorsal capsular flap and the remainder of the dorsal capsule were closed using interrupted 2-0 Ethibond sutures, followed by closure of the extensor retinaculum and skin. This condition, which is referred to as cut, then had radiographic imaging in both the PA and lateral radiographic views in all wrist positions, using the loading conditions described earlier. The first surgical stabilization procedure to be performed on the unstable specimen was determined by the toss of a coin, resulting in the MBT being performed initially. The MBT was performed as described in the literature.28 The volar skin was reopened, exposing the distally attached FCR tendon slip. Removing the previous skin, retinaculum, and capsule sutures exposed the dorsal scaphoid. A K-wire was then drilled through the dorsal bare area on the scaphoid and exited the volar distal pole of the scaphoid. A cannulated 3.2-mm drill was then used to drill through the scaphoid. The FCR tendon slip was then passed from the volar surface through the scaphoid, exiting dorsally. A 3.5-mm TwinFix suture anchor with number 2 DuraBraid suture (Smith & Nephew, London, UK) was then placed into the lunate, positioned at the lunate insertion of the SL ligament. The FCR tendon slip was passed dorsally across the lunate and looped around the radiotriquetral ligament. The scaphoid and lunate were reduced by manual manipulation while we simultaneously tensioned the FCR tendon slip until the joint surfaces matched the anatomic alignment before ligament sectioning, as judged by the surgeon. Once the SL interval was reduced, the FCR tendon slip was sutured to the dorsal surface of the lunate, using the suture from the suture anchor. The FCR was further secured by suturing the free end of the tendon slip back to itself on the dorsum of the lunate. The dorsal capsule, extensor retinaculum, and both volar and dorsal skin incisions were closed. Next, the specimen was again secured to the plywood using the external fixator, and radiographic imaging was obtained. The specimen was then removed from the frame, the Brunelli reconstruction was taken down, and the BC was performed, as described in the literature.17 A similar 3.5-mm TwinFix suture anchor (Smith & Nephew) was placed in the dorsal scaphoid distal to the axis of rotation and 3 mm from the scaphotrapezio-trapezoidal joint. The scaphoid and lunate were reduced by manual manipulation until the joint surfaces matched the anatomic alignment before ligament sectioning. The 1-cm-
FIGURE 3: An SL interval measurement on a PA radiograph. Reprinted with permission from Green’s Operative Hand Surgery, 5th ed., Vol. 1, Garcia-Elias M, Geissler WB, Carpal instability, pp. 535– 604, Copyright Elsevier, 2005.
wide dorsal capsular flap was secured to the distal dorsal scaphoid, using the suture anchor. Suturing the free capsule tissue margins to the 3 sides of the 1-cmwide capsule flap closed the dorsal capsule. The extensor retinaculum and skin were closed with sutures, the specimen was again secured to the frame, and radiographic imaging was performed. Each subsequent specimen was chosen from the supply of cadaver extremities in a random order and tested in a similar manner. The order of the procedures alternated. The second and fourth specimens started with BC, and the third and fifth specimens started with the MBT. The second surgical reconstruction procedure was left intact in each specimen, leaving 3 with the BC and 2 with the MBT, in order to evaluate the durability of each procedure after simulated wrist motion. Each wrist was carefully cycled manually by the senior author (P.J.P.) from flexion to extension, reaching the extent of the soft tissue constraints through 100 repetitions, and imaging was repeated. We chose 100 cycles to allow adequate creep of the soft tissues and to likely reach a stable final end state of the reconstructive procedures. After completion of testing on all 5 specimens, the digital images were downloaded to a computer software program (Adobe Photoshop 6.0; Adobe Systems Inc., San Jose, CA) to measure the SL interval and both the SL and the radiolunate (RL) angles. The SL interval was measured on PA radiographs as the distance between the midpoint of the scaphoid and the lunate (Fig. 3). A 4.54-cm-long K-wire, measured by a commercially available digital caliper (Small Mode SPI 2000
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FIGURE 4: Carpal angle determination. This figure demonstrates 3 illustrated lateral radiographic views of the wrist carpals. A Line “S” represents a parallel line drawn along the volar surface of the scaphoid. B Line “L” represents a line drawn perpendicular to the 2 distal poles of the lunate. C Line “R” represents a line drawn parallel to the medullary canal of the radius. Reprinted with permissin from Green’s Operative Hand Surgery, 5th ed., Vol. 1, Garcia-Elias M, Geissler WB, Carpal instability, pp. 535– 604, Copyright Elsevier, 2005.
31– 415–3; Mitutoyo, Aurora, IL) was included in the PA radiographs of all specimens to calibrate length measurements, eliminating the effect of magnification to improve assessment of the SL interval. The wire was placed by hand transversely, just proximal to the carpal bones on the volar surface of the radius. The length of the wire was measured by the software program and recorded to the same degree of accuracy as the caliper. The SL interval was measured as recommended by Kindynis, using the software program.36 The true SL interval was then calculated by using the conversion factor derived from the known length of the wire to correct for magnification. The SL angle was measured on lateral radiographs using the volar surface of the scaphoid and a perpendicular line drawn from the 2 distal poles of the lunate (Fig. 4).35 The RL angle was measured according to the line drawn perpendicular to the 2 distal poles of the lunate and a line parallel to the medullary canal of the radius (Fig. 4).35 An independent power analysis on SL interval indicated that a sample size of 5 would allow an 80% chance of detecting a 30% change at the .05 probability level, assuming a standard deviation in SL interval size of 0.5 mm. The statistical analysis was performed using a repeated-measure analysis of variance, with significance set at p⬍.05. This analysis allowed each of the 5 intact specimens to act as the control for the subsequent measurements on the same cadaver specimen. To determine which of the 4 different conditions (intact, cut, MBT, BC) were significantly different from the rest, a range of nonsignificance was determined using a Tukey
test with significance set at p⬍.05. The cycled specimens were analyzed separately. The magnitude of change from precycling to postcycling was determined for both the MBT and BC specimens and compared using Student’s t-test with significance set at p⬍.05. RESULTS Scapholunate interval The SL interval increased in all wrist positions after SL dissociation was surgically created. This was statistically significant (p⬍.05) with the wrist in flexion, radial deviation, and the clenched fist position. The clenched fist position demonstrated the greatest increase, from 2.9 ⫾ 0.6 mm (mean ⫾ SD) when the ligaments were intact to 5.0 ⫾ 0.3 mm when the ligaments were sectioned. The clenched fist radiograph maximally stresses the SL ligament and has been shown in the literature to best evaluate SL instability.37 The first row of Table 1 summarizes the SL interval obtained for all 4 conditions (intact, cut, MBT, BC) of the SL ligaments with the wrist in the clenched fist position and the additional change in SL interval with cycling. Surgical reconstruction using the MBT better restored the normal SL interval than did the BC (Fig. 5). After the MBT, there were no significant differences in the SL interval when compared to the intact specimens in any wrist position. After the BC, the SL interval remained significantly increased (p⬍.05) compared with the intact specimens when the wrist was placed in the clenched fist position. There were no significant
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TABLE 1. Average SL Interval in the Clenched Fist Position, Average SL Angle in the Clenched Fist Position, and Average RL Angle in Radial Deviation for All Wrist Conditions of the SL Ligaments
1. Scapholunate interval in the clenched fist position (mean ⫾ SD; mm)
Intact
Cut
MBT
BC
2.9 ⫾ 0.6
5.0 ⫾ 0.3*
2.6 ⫾ 0.6
4.6 ⫾ 0.4*
2. Scapholunate angle in the clenched 54.8 ⫾ 6.1 70.5 ⫾ 3.4* 58.8 ⫾ 3.1 67.2 ⫾ 3.7* fist position (mean ⫾ SD; °) 4.0 ⫾ 1.6 16.3 ⫾ 7.1*
3. Radiolunate angle in radial deviation (mean ⫾ SD; °)
9.2 ⫾ 2.1
6.4 ⫾ 6.3
MBT Change With BC Change With Cycling (n⫽2) Cycling (n⫽3) 0.3 ⫾ 0.4
0.3 ⫾ 0.5
⫺0.6 ⫾ 1.1†
3.3 ⫾ 0.7†
6.0 ⫾ 2.8
0.7 ⫾ 3.5
*Denotes statistically significant difference from the intact state. †Denotes statistically significant difference between MBT and BC for cycled specimens.
6 5 neutral 4
flexion extension
3
radial ulnar
2
fist 1 0 Intact
Cut
MBT
BC
MBT Cycled
BC Cycled
FIGURE 5: Average SL interval for all conditions and positions (mm).
differences in the SL interval when compared to the intact specimens for the other wrist positions after BC. In addition to comparing the intact group with each reconstructed group, comparisons were made between the 2 reconstructed groups. In the clenched fist position, there was a significant increase in the SL interval measured after BC compared with MBT (4.6 ⫾ 0.4 mm vs 2.6 ⫾ 0.6 mm, respectively; p⬍.05). No significant differences were noted with the other wrist positions. After simulated wrist motion, there were no significant differences in the magnitude of change from precycling to postcycling in the 2 MBT cycled specimens or in the 3 BC specimens. Scapholunate angle The SL angle demonstrated increased values in all wrist positions after SL dissociation was surgically created. This was statistically significant (p⬍.05) with the wrist in radial deviation and in the clenched fist position. The
clenched fist position demonstrated the greatest increase, from 54.8° ⫾ 6.1° when the ligaments were intact to 70.5° ⫾ 3.4° when the ligaments were sectioned. The second row of Table 1 summarizes the SL angle obtained for all 4 conditions (intact, cut, MBT, BC) of the SL ligaments with the wrist in the clenched fist position and the additional change in SL angle with cycling. Surgical reconstruction using the MBT better restored the normal SL angle than did the BC (Fig. 6). After the MBT, there were no significant differences in the SL angle when compared to the intact specimens in any wrist position. After the BC, the SL angle remained statistically increased (p⬍.05) compared with the intact specimens when the wrist was placed in flexion and in the clenched fist position. There were no significant differences in the SL angle when compared to the intact specimens for the other wrist positions after BC. There was a statistically significant increase in the SL angle measured after BC compared with the MBT in
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90 80 70
neutral
60
flexion
50
extension
40
radial
30
ulnar
20
fist
10 0 Intact
Cut
MBT
BC
MBT Cycled
BC Cycled
FIGURE 6: Average SL angle for all wrist conditions and positions (°).
RL angle 50 40 neutral
30
flexion
20
extension
Extension 10
radial ulnar
0
Flexion 10
fist
Intact
Cut
MBT
BC
MBT Cycled
BC Cycled
20 FIGURE 7: Average RL angle for all wrist conditions and positions (°).
the clenched fist position (67.2° ⫾ 3.7° vs 58.8° ⫾ 3.1°, respectively; p⬍.05) and flexion (80.7° ⫾ 2.3° vs 64.9° ⫾ 4.9°, respectively; p⬍.05). After simulated wrist motion, there was a significant difference in the magnitude of change from precycling to postcycling between the MBT and BC in the clenched fist position (p⫽.016). On average, the SL angle for the 2 cycled MBT specimens changed by ⫺0.6 ⫾ 1.1 mm and the 3 BC specimens changed by 3.3 ⫾ 0.7 mm (Table 1). Radiolunate angle As expected, after SL dissociation was surgically created, the RL angle demonstrated increases in lunate extension with most wrist positions except extension and the clenched fist position. Both of these wrist po-
sitions result in extension of the entire carpus in relationship to the radius, which naturally extends the lunate and possibly matches or surpasses the magnitude of abnormal lunate extension seen with SL dissociation. Only with the wrist in radial deviation was the increased lunate extension statistically significant, increasing from 4.0° ⫾ 1.6° when the ligaments were intact to 16.3° ⫾ 7.1° when the ligaments were sectioned (p⬍.05). The third row in Table 1 summarizes the RL angle obtained for all 4 conditions (intact, cut, MBT, BC) of the SL ligaments with the wrist in radial deviation and the additional change in RL angle with cycling. After surgical reconstruction, both the MBT and the BC demonstrated no statistically significant differences in RL angle when compared to the intact specimens.
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Figure 7 shows the average RL angles for all wrist conditions of the SL ligaments and loading positions. With the wrist in radial deviation, the MBT corrected the RL angle to a final value of 9.2° ⫾ 2.1°, whereas the BC corrected the RL angle to a final value of 6.4° ⫾ 6.3°. There was no statistically significant difference for the amount of RL angle correction with the wrist in radial deviation when comparing the 2 procedures. After simulated wrist motion, there were no significant differences in the magnitude of change from precycling to postcycling between the MBT and the BC for any wrist position. DISCUSSION Since Blatt first described the dorsal capsulodesis in 1987, numerous treatments have been developed, and continue to be developed, for SL dissociation, suggesting persistent disappointment with current outcomes from the described surgical procedures. The BC is still commonly performed. One intuitive criticism of the BC is that the reconstruction is nonanatomic. Reconstructing the ligamentous anatomy to restore the normal carpal relationships would be expected to result in normal forces being distributed to the articular surfaces of the carpals, relieving pain, preventing degenerative changes, and restoring wrist function. The commonly performed BC is a soft tissue procedure that attempts to preserve the majority of wrist motion. The associated loss of wrist flexion is believed to be secondary to the dorsal tether of the scaphoid to the radius. The MBT has the theoretical advantage of a more anatomic correction of SL dissociation. The FCR tendon slip is attached distally and volarly at its normal insertion on the index metacarpal. This prevents the distal pole of the scaphoid from flexing by reconstructing or reinforcing the volar ligaments, which are thought to be secondary stabilizers that are injured or lax. This FCR tendon slip is passed through the body of the scaphoid, exits the dorsum of the proximal scaphoid, and is secured to the dorsal lunate, reconstructing the normal anatomy of the dorsal SLIL. The FCR tendon slip is tensioned, using the distal portion of the dorsal radiotriquetral ligament to act as a pulley and reduce the SL interval, by pulling the proximal scaphoid ulnarly toward the lunate. Although this part of the modified procedure is not anatomic, looping the FCR slip around the dorsal radiotriquetral ligament does effectively reattach the lunate to the dorsal radiotriquetral ligament, which is normal. The abnormal lunate extension is corrected under direct visualization and theoretically held in place by the reconstructed dorsal SL ligament.
In our study, BC poorly corrected the SL interval and angle after SL dissociation and demonstrated an increase in SL angle after simulated wrist motion compared to MBT. The MBT better corrected the SL interval and angle and maintained the SL angle after wrist motion. The difference in correction of the RL angle between the 2 procedures did not reach statistical significance. The number of specimens in the cycled groups consisted of only 2 specimens in the MBT group and 3 specimens in the BC group. There was a trend toward increased lunate extension after cycling the MBT specimens in several wrist positions. Perhaps the FCR tendon, which is secured to the dorsal lunate and distal to the axis of rotation for lunate flexion and extension, has a tendency to hyperextend the lunate. If this does occur in vivo, it could result in abnormal articulation between the lunate and capitate and proceed with degenerative changes similar to those seen with SL advanced collapse. Previous authors have reported the radiographic outcomes of both the BC and the MBT clinically and in cadaveric models. Moran et al.19 retrospectively evaluated the BC in 11 patients. Initial postoperative radiographs demonstrated a decrease in the SL interval and angle, but after an average follow-up evaluation of 54 months, the correction of both was lost. Slater et al.32 evaluated the BC radiographically in a cadaveric model. After surgical correction, the BC failed to restore the SL interval (p⬍.05). Links et al.31 retrospectively evaluated 21 patients who received the MBT, after an average follow-up of 29 months. When compared to preoperative radiographs, there was an average 15° ⫾ 5° decrease in the SL angle and 1.6 ⫾ 0.8 mm decrease in the SL interval. Moran et al.28 retrospectively analyzed 15 patients who had surgical reconstruction for chronic SL instability using the MBT, at an average follow-up of 36 months. When compared to preoperative radiographs, the SL angle correction was maintained and found to be statistically significant (p⫽.04). Both of these studies suggest that the MBT corrects and maintains the normal carpal relationship for a minimum of 3 years. However, in a retrospective analysis of 19 patients with a mean follow-up of 37 months after MBT, Chabas et al.30 reported a loss of the SL angle correction that was present immediately after surgery. Thus, there are conflicting data for the efficacy of the MBT to maintain carpal anatomy. To our knowledge, only one cadaveric study has been performed to evaluate the radiographic outcomes of the MBT. In 2008, Howlett et al.38 compared distal-
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exiting scaphoid tunnel placement with proximalexiting tunnel placement using Mersilene tape (Ethicon, Inc., Somerville, NJ) in place of the FCR tendon. After surgical reconstruction, the SL angle decreased to within 15° ⫾ 10° of the mean intact specimen for the proximal tunnel and 4° ⫾ 7° for the distal tunnel. This difference was statistically significant (p⬍.05) in favor of distal tunnel placement. The SL interval significantly decreased (p⬍.05) for both groups when compared to the intact specimen; however, there was no statistical difference between the 2 groups when comparing the 2 tunnel placements alone. Limitations of this study include the use of Mersilene tape (Ethicon, Inc.), which, according to Howlett, is stiffer than tendon and does not accurately represent an in vivo model. In addition, there were no measurements after simulated wrist motion to evaluate the ability to maintain correction. This study has several limitations. The specimens are cadavers and do not allow healing of tissue to provide more durable reconstructions, especially tendon healing to bone. The correlation between radiographic measurements and clinical outcomes—such as pain relief, wrist motion, and grip strength—is not known. Also, assumptions cannot be made on long-term clinical outcomes as they relate to radiographic measurements and degenerative changes. The static PA and lateral radiographs measuring 3 carpal relationships does not fully evaluate the static and dynamic relationship of the carpal bones, which Berdia described as being a complex relationship that depends on wrist position and the direction of wrist motion.39 Although there was a statistically significant difference in the magnitude of change of the SL angle between the MBT and BC for the cycled specimens, only a small number of specimens were used for this part of the investigation. Additional studies are required to evaluate the durability of these reconstructive procedures. The MBT prevents scaphoid flexion by 2 points of fixation with a distal volar buttress and proximal dorsal tether. The SL interval is directly reduced by ulnarly directed tension on the proximal scaphoid, recreating the dorsal SL ligament. This results in greater corrections of both the SL interval and the SL angle, and it better withstands simulated wrist motion when compared to the BC. The BC tethers the scaphoid distally to prevent flexion, but it does not secure the proximal scaphoid. The SL interval is reduced after the BC indirectly, as scaphoid flexion is corrected. The improved radiographic measurements observed with the MBT imply improved anatomic restoration in cadavers and potentially improved clinical outcomes in patients. Further long-term clinical studies to compare radio-
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graphic correction, degenerative changes, and patient outcomes are needed to determine the optimal surgical treatment for chronic SL instability. REFERENCES 1. Jones WA. Beware the sprained wrist. The incidence and diagnosis of scapholunate instability. J Bone Joint Surg 1988;70B:293–297. 2. Watson HK, Ballet FL. The SLAC wrist: scapholunate advanced collapse pattern of degenerative arthritis. J Hand Surg 1984;9A:358 – 365. 3. Stanley JK, Trail IA. Carpal instability. J Bone Joint Surg 1994;76B: 691–700. 4. Hom S, Ruby LK. Attempted scapholunate arthrodesis for chronic scapholunate dissociation. J Hand Surg 1991;16A:334 –339. 5. Augsburger S, Necking L, Horton J, Bach AW, Tencer AF. A comparison of scaphoid-trapezium-trapezoid fusion and four-bone tendon weave for scapholunate dissociation. J Hand Surg 1992; 17A:360 –369. 6. Garcia-Elias M, Cooney WP, An KN, Linscheid RL, Chao EY. Wrist kinematics after limited intercarpal arthrodesis. J Hand Surg 1989; 14A:791–799. 7. Bleuler P, Shafighi M, Donati OF, Gurunluoglu R, Constantinescu MA. Dynamic repair of scapholunate dissociation with dorsal extensor carpi radialis longus tenodesis. J Hand Surg 2008;33A:281–284. 8. Opreanu RC, Baulch M, Katranji A. Reduction and maintenance of scapholunate dissociation using the TwinFix screw. Eplasty 2009;9:e7. Epub 2009 Jan 29. 9. Szabo RM. Scapholunate ligament repair with capsulodesis reinforcement. J Hand Surg 2008;33A:1645–1654. 10. Harvey EJ, Berger RA, Osterman AL, Fernandez DL, Weiss AP. Bone-tissue-bone repairs for scapholunate dissociation. J Hand Surg 2007;32A:256 –264. 11. Minami A, Kato H, Iwasaki N. Treatment of scapholunate dissociation: ligamentous repair associated with modified dorsal capsulodesis. Hand Surg 2003;8:1– 6. 12. Schweizer A, Steiger R. Long-term results after repair and augmentation ligamentoplasty of rotatory subluxation of the scaphoid. J Hand Surg 2002;27A:674 – 684. 13. Szabo RM, Slater RR Jr, Palumbo CF, Gerlach T. Dorsal intercarpal ligament capsulodesis for chronic, static scapholunate dissociation: clinical results. J Hand Surg 2002;27A:978 –984. 14. Dunn MJ, Johnson C. Static scapholunate dissociation: a new reconstruction technique using a volar and dorsal approach in a cadaver model. J Hand Surg 2001;26A:749 –754. 15. Short WH, Werner FW, Sutton LG. Treatment of scapholunate dissociation with a bioresorbable polymer plate: a biomechanical study. J Hand Surg 2008;33A:643– 649. 16. Zarkadas PC, Gropper PT, White NJ, Perey BH. A survey of the surgical management of acute and chronic scapholunate instability. J Hand Surg 2004;29A:848 – 857. 17. Blatt G. Capsulodesis in reconstructive hand surgery. Dorsal capsulodesis for the unstable scaphoid and volar capsulodesis following excision of the distal ulna. Hand Clin 1987;3:81–102. 18. Short WH, Werner FW, Green JK, Masaoka S. Biomechanical evaluation of ligamentous stabilizers of the scaphoid and lunate: part II. J Hand Surg 2005;30A:24 –34. 19. Moran SL, Cooney WP, Berger RA, Strickland J. Capsulodesis for the treatment of chronic scapholunate instability. J Hand Surg 2005; 30A:16 –23. 20. Pomerance J. Outcome after repair of the scapholunate interosseous ligament and dorsal capsulodesis for dynamic scapholunate instability due to trauma. J Hand Surg 2006;31A:1380 –1386. 21. Deshmukh SC, Givissis P, Belloso D, Stanley JK, Trail IA. Blatt’s capsulodesis for chronic scapholunate dissociation. J Hand Surg 1999;24B:215–220.
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31. Links AC, Chin SH, Waitayawinyu T, Trumble TE. Scapholunate interosseous ligament reconstruction: results with a modified Brunelli technique versus four-bone weave. J Hand Surg 2008;33A:850 – 856. 32. Slater RR Jr, Szabo RM, Bay BK, Laubach J. Dorsal intercarpal ligament capsulodesis for scapholunate dissociation: biomechanical analysis in a cadaver model. J Hand Surg 1999;24A:232–239. 33. Brand PW, Beach RB, Thompson DE. Relative tension and potential excursion of muscles in the forearm and hand. J Hand Surg 1981; 6A:209 –219. 34. Schuind FA, Linscheid RL, An KN, Chao EY. A normal data base of posteroanterior roentgenographic measurements of the wrist. J Bone Joint Surg 1992;74A:1418 –1429. 35. Larsen CF, Mathiesen FK, Lindequist S. Measurements of carpal bone angles on lateral wrist radiographs. J Hand Surg 1991;16A: 888 – 893. 36. Kindynis P, Resnick D, Kang HS, Haller J, Sartoris DJ. Demonstration of the scapholunate space with radiography. Radiology 1990; 175:278 –280. 37. Lawand A, Foulkes GD. The “clenched pencil” view: a modified clenched fist scapholunate stress view. J Hand Surg 2003;28A:414 – 418. 38. Howlett JP, Pfaeffle HJ, Waitayawinyu T, Trumble TE. Distal tunnel placement improves scaphoid flexion with the Brunelli tenodesis procedure for scapholunate dissociation. J Hand Surg 2008;33A: 1756 –1764. 39. Berdia S, Short WH, Werner FW, Green JK, Panjabi M. The hysteresis effect in carpal kinematics. J Hand Surg 2006;31A:594 – 600.
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