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SCIENTIFIC ARTICLE

Range of Motion Effects of Distal Pole Scaphoid

Excision and Triquetral Excision After

Radioscapholunate Fusion: A Cadaver Study

Khurram Pervaiz, MD,William H. Bowers, MD, Jonathan E. Isaacs, MD, John R. Owen, BS,Jennifer S. Wayne, PhD

Purpose Radioscapholunate (RSL) fusion is an effective surgical procedure for the treatmentof isolated radiocarpal arthritis. Although functional wrist motion is typically preservedthrough the midcarpal joint, many patients are still frustrated by postoperative limitations.The purpose of this study was to evaluate motion of cadaver wrists after simulated RSLfusion with excision of the distal pole of the scaphoid and the triquetrum.

Methods Ten fresh-frozen cadaver upper extremities were mounted on a custom testingapparatus after isolation of the flexor carpi radialis, flexor carpi ulnaris, extensor carpiradialis longus, and extensor carpi ulnaris tendons. Sequential loading of these tendonsresulted in flexion, extension, radial, and ulnar deviation. We subsequently measured rangeof motion with the use of digital photography. All specimens were tested in 4 states: intact(normal), RSL fusion (simulated), RSL fusion with distal scaphoid pole excision, and RSLfusion with distal scaphoid pole and triquetrum excision. The results were statisticallyanalyzed using a repeated measures analysis of variance.

Results Range of motion decreased to 39% to 46% of normal for flexion and extension and65% to 71% of normal for radial and ulnar deviation after simulated RSL fusion. Theaddition of distal pole of scaphoid excision resulted in flexion and extension returning to 72%to 79% of normal, and radial and ulnar deviation returning to 84% to 89% of normal.Excision of the triquetrum further increased flexion and extension to 87% to 97% of normal,and radial and ulnar deviation to 119% to 137% of normal.

Conclusions The combination of triquetral and distal scaphoid pole excision after RSL fusionimproves wrist motion to levels close to normal in the cadaver model. (J Hand Surg 2009;34A:832–837. Copyright © 2009 by the American Society for Surgery of the Hand. All rightsreserved.)Key words Radioscapholunate arthrodesis, distal scaphoid pole excision, wrist motion,radiocarpal arthritis.

rom

SOLATED RADIOCARPAL ARTHRITIS is most commonlyrelated to incongruent healing of the distal radialarticular surface after intra-articular fracture.1 When

onservative options are unable to provide adequate

From the Orthopaedic Research Laboratory, Departments of Orthopaedic Surgery and Biomedical Engi-neering, Virginia Commonwealth University; and the Hunter H. McGuire Veterans Affairs Medical Center,Richmond, Virginia.

Received for publication July 22, 2008; accepted in revised form February 6, 2009.

No benefits in any form have been received or will be received related directly or indirectly to the

subject of this article.

32 � © ASSH � Published by Elsevier, Inc. All rights reserved.

elief of resulting pain and stiffness, several surgicalptions exist including total wrist fusion, wrist replace-ent, and denervation. Radioscapholunate (RSL) fu-

ion is a particularly attractive option because it per-

orresponding author: Jennifer S. Wayne, PhD, P.O. Box 843067, Virginia Commonwealth Univer-ity, Richmond, VA 23284-3067; e-mail: jwayne@vcu.edu.

363-5023/09/34A05-0005$36.00/0oi:10.1016/j.jhsa.2009.02.007

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TRIQUETRAL AND DISTAL SCAPHOID POLE EXCISION 833

manently obliterates the painful RSL joint whilemaintaining some wrist motion across the preservedmidcarpal joint.1–3 Although this retained motion,which typically averages 33% to 40% of normal,1,2,4

is functionally useful, in our experience, patients arestill frustrated by the limitations. Efforts to improvepost-RSL fusion motion have included excision ofthe distal pole of the scaphoid. The intact scaphoidspans both the proximal and distal carpal rows andremoval of the distal pole unlocks the midcarpaljoint.4 Cadaveric biomechanical and clinical out-come studies have demonstrated modest improve-ments of 15% to 25% in range of motion after exci-sion of the distal pole.1,2,4 We hypothesize that thetriquetrum represents a second mechanical block tomidcarpal motion after RSL fusion with distal scaph-oid pole excision. The senior author (W.B.) has notedclinical improvement when triquetral excision hasbeen included as part of the index procedure. Thepurpose of this study was to evaluate motion of

FIGURE 1: Schematic of custom-designed loading apparatus tdeviation by applying 5-lb weights to selected tendons.

cadaver wrists after simulated RSL fusion with ex-

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cision of the distal pole of the scaphoid and thetriquetrum.

MATERIALS AND METHODSWe used 10 fresh-frozen, upper-extremity cadaverspecimens in this study, with an age range of 49 to 81years (65 � 13 SD years). None had evidence of wristtrauma, arthritis, or previous surgery. Each above-elbow specimen was mounted onto a custom-designedtesting frame (Fig. 1) with 2 0.125-inch (3.2-mm) di-ameter K-wires drilled through the radius and ulna tomaintain the forearm in a vertical position. To replicatephysiologic motion in the cadaver wrists, 4 tendonsproximal to the wrist were isolated and prepared forattachment of weights during the simulated range ofmotion: the flexor carpi radialis (FCR), flexor carpiulnaris (FCU), extensor carpi radialis longus (ECRL),and extensor carpi ulnaris (ECU). Each tendon wasattached to a 5-lb weight through synthetic wire forloading. These tendons were loaded in sequence to

duce alternately flexion, extension, radial deviation, and ulnar

o pro

reproduce flexion, extension, radial, and ulnar deviation

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834 TRIQUETRAL AND DISTAL SCAPHOID POLE EXCISION

in the wrist. The FCR and FCU were loaded together toreproduce flexion, the ECRL and ECU to reproduceextension, the FCR and ECRL for radial deviation, andthe ECU for ulnar deviation.

To track skeletal motion for calculating range ofmotion in flexion, extension, radial deviation, and ulnardeviation, 4 black markers were placed strategically inthe bones: 2 along the long axis of the radius and 2along the long axis of the third metacarpal. For eachmotion, the respective tendon(s) were loaded 5 timesfor 15 seconds each time, with a 5-second intervalbetween loads to account for soft tissue creep. Using aPanasonic PV-GS35 Digital Palmcorder (PanasonicCorporation of North America, Secaucus, NJ), we ob-tained digital images of the last 3 cycles to documentwrist position for range of motion calculations. Thecamera was positioned 30 cm away from the specimenin the coronal plane for flexion-extension motion and40 cm in the sagittal plane for radial-ulnar deviationmeasurements. The digital photographs were importedinto standard NIH Image J software (National Institutesof Health, Bethesda, MD), and angles between the 2sets of markers were measured to calculate the flexion-extension and radial-ulnar deviation arcs of motion.

We measured flexion, extension, and radial and ulnardeviation for each specimen in each of 4 states: intact(normal), RSL fusion (simulated), RSL fusion withdistal scaphoid pole excision, and RSL fusion withdistal scaphoid pole and triquetrum excision. To repre-sent the fused state, the radiocarpal joint was fixed byplacing 2 0.0625-inch (1.6-mm) diameter K-wiresacross both the radioscaphoid and radiolunate joints(Fig. 2). Wire placement and fusion alignment werethen confirmed with fluoroscopy (XiScan1000 C-armfluoroscope; XiTec Inc., Windsor Locks, CT). After

FIGURE 2: Digital radiographs documenting A RSL fusion viscaphoid, and C RSL fusion with removal of the distal pole of

measurements for this new state were obtained, the

JHS �Vol A, Ma

wrist then underwent excision of the distal pole of thescaphoid. A 5-cm longitudinal incision was madethrough the floor of the FCR sheath and the volar wristcapsule including the radioscaphocapitate ligament.The osteotomy level was marked just distal to the waistof the scaphoid as determined by fluoroscopic imagingand performed with a 10-mm oscillating saw (Model4100-400; Stryker, Allendale, NJ). After removal of thedistal pole, the volar capsule and ligaments were re-paired with 4–0 vicryl suture (Polygalactin 910; Ethi-con, Somerville, NJ). Finally, the triquetrum was ap-proached via a 3-cm dorsal incision directly over thetriquetrum and sharply excised using gentle traction anda number 15 scalpel blade. We repaired the dorsalcapsule and ligaments using 4–0 vicryl suture (Polyga-lactin 910; Ethicon). These incisions were designed forthe experiment and do not suggest clinical application.

We performed statistical analyses on each of the 4motions via a repeated-measures analysis of variance toassess the effects of wrist state (intact, RSL fusion, RSLfusion with distal scaphoid pole excision, and RSLfusion with distal scaphoid pole and triquetrum exci-sion). A significance level of p � .05 was consideredstatistically different.

RESULTSThe average range of motion for the intact (normal)wrist was 70° of flexion, 56° of extension, 30° of radialdeviation, and 31° of ulnar deviation. Range of motionwas found to decrease significantly to 39% of normalfor flexion, 46% of normal for extension, 65% of nor-mal for radial deviation, and 71% of normal for ulnardeviation after simulated RSL fusion (Fig. 3, Table 1).

Distal pole scaphoid excision after fusion resulted inimprovement in all 4 motions, with the maximum effect

-wires, B RSL fusion with removal of the distal pole of thecaphoid and triquetrum excision.

a 4 K

on flexion, extension, and radial deviation. Flexion,

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TRIQUETRAL AND DISTAL SCAPHOID POLE EXCISION 835

extension, and radial deviation motions were each sta-tistically greater than RSL fusion alone but still signif-icantly lower than normal. Ulnar deviation motion didnot increase substantially over RSL-alone values.

Excision of the triquetrum brought further gains in

FIGURE 3: Range of motion in flexion, extension, and radiafusion, RSL fusion with distal pole (DP) of the scaphoid remov

TABLE 1. Range of Motion for Intact (Normal)Wrist (SD) and Percentage of Intact for RSLFusion, RSL Fusion With Distal Pole (DP) ofScaphoid Removed, and RSL Fusion With DPand Triquetrum (Tri) Removed

IntactRSL

FusionDP

ExcisedTri

Excised

Flexion 70 (7)° 39% 79% 87%

*p � .001 *p � .001 *p � .001

†p � .001 †p � .001

‡p � .031

Extension 56 (8)° 46% 72% 97%

*p � .001 *p � .001 *p � .79

†p � .001 †p � .001

‡p � .001

Radialdeviation

30 (8)° 65% 89% 119%

*p � .001 *p � .05 *p � .009

†p � .001 †p � .001

‡p � .001

Ulnardeviation

31 (5)° 71% 84% 137%

*p � .001 *p � .016 *p � .001

†p � .1 †p � .001

‡p � .001

Statistical differences relative to *intact state, †fused state, and‡fused with DP excised state.

ROM, with its maximum effect on radial, ulnar devia-

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tion, and extension. In both flexion and extension, mo-tion statistically improved beyond RSL fusion alone orwith the addition of pole excision. However, only ex-tension motion was not significantly different from nor-mal. Both radial and ulnar deviations significantly im-proved beyond RSL fusion alone, or with the additionof pole excision, to levels that were above normal.

DISCUSSIONIsolated RSL osteoarthritis is primarily a posttraumaticcondition resulting from intra-articular distal radiusfractures. Nonsurgical treatment options include activ-ity modification, temporary immobilization, nonsteroi-dal anti-inflammatory medications, and selective intra-articular injections of corticosteroids. In many patientswith more advanced disease, however, the pain reliefgained by these efforts is limited.1 For these patients,multiple surgical options have been described includingtotal wrist fusion, denervation, wrist arthoplasty, andRSL fusion.1–5

Radioscapholunate fusion theoretically obliteratespain generators at the damaged RSL joint while main-taining some wrist motion across the preserved midcar-pal joint. Previous cadaver studies by McCombe et al.4

have shown that the range of motion falls to 42% ofnormal for the flexion-extension arc and 69% of normalfor the radial-ulnar deviation arc after an RSL fusion. Inour study, the flexion extension arc dropped to 39% to46% of normal with simulated RSL fusion, whereas theradial-ulnar deviation arc suffered a more modest de-crease, dropping to 65% to 71% of normal.

This amount of retained motion should be adequateto accomplish most activities of daily living. Review ofthe literature indicates that approximately 5° to 40° of

ulnar deviation for each of the states: intact (normal), RSLnd RSL fusion with DP and triquetrum (TRI) removed.

l and

flexion, 30° to 40° of extension, 10° of radial deviation,

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836 TRIQUETRAL AND DISTAL SCAPHOID POLE EXCISION

and 15° to 30° of ulnar deviation would be needed forday-to-day activities.6–10 The amount of retained mo-tion, however, may still be unsatisfactory to many pa-tients. The limitation of data assessing functionalmotion is that they do not consider strenuous orrepetitive tasks such as sports or physically demand-ing activities that would conceivably be more af-fected by loss of wrist motion.6 In addition, recentwork by Adams et al. has shown that reduced wristmotion increases the time to task performance.6

Several recent articles have emphasized the impor-tance of the dart thrower’s motion for most occupa-tional and vocational activities.11,12 Palmer et al. andWolfe et al. showed that many occupational activities,exemplified by hammer use, involved an arc of motionfrom radial deviation and wrist extension to ulnar de-viation and wrist flexion.9,11 Much of this motioncomes from the midcarpal joint but is lost by the block-ing effect of the scaphoid that bridges the proximal anddistal carpal row after RSL fusion.11–15 Other investi-gators have noted the compromised motion affected bythis block.2,4

Excision of the distal pole of the scaphoid to unlockthe midcarpal joint is one technique for improvingpost-RSL fusion motion.2,4 Improvements in motionhave been well documented in cadaveric and clinicaloutcomes studies.2,4,16 In their cadaver study, McCombeet al. found that the flexion-extension arc fell to 42%after RSL fusion and improved to 86% after distalscaphoid pole excision.4 Similarly the radial-ulnardeviation arc that fell to 69% after RSL fusion in-creased to 87% after distal scaphoid pole excision.Clinical work by Garcia-Elias et al.2 and Garcia-Elias and Lluch17 showed that range of motion withRSL arthrodesis (18° of flexion, 31° of extension, 6°of radial deviation, and 17° of ulnar deviation) im-proved considerably with a distal scaphoidectomy, to32° of flexion, 35° of extension, 14° of radial devi-ation, and 19° of ulnar deviation. In our study, theflexion-extension arc dropped to 39% to 46% ofnormal with RSL fusion increasing to 72% to 79%with distal scaphoid pole excision. The radial-ulnardeviation arc suffered a modest decrease comparedwith the flexion-extension arc, dropping to 65% to71% of normal after RSL fusion. Distal scaphoidpole excision increased this to 84% to 89% of nor-mal.

Whereas excision of the distal pole of the scaphoidshould alter vascular perfusion of the proximal scaph-oid pole and theoretically hinder the bone healing nec-essary for successful fusion, this did not turn out to be

the case in the studies by Garcia-Elias et al. and Garcia-

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Elias and Lluch. They reported improved fusion rates:no nonunions in their RSL fusion with distal pole ex-cision patients versus 6% to 27% reported nonunionrate with RSL fusion alone in previous studies.2,16–19

Those authors also reported a lower incidence of mid-carpal arthritis: 33% with RSL fusion alone versus 12%with RSL fusion combined with distal pole excision.2,16

They rationalized that distal scaphoid pole excisionremoves a strong lever arm and actually unloads theRSL arthrodesis so that fusion rates improve and inci-dence of secondary midcarpal arthritis decreases.

The triquetrum may represent a secondary blockadeto motion after RSL fusion. The senior author (W.B.)has noted clinical improvement when triquetral exci-sion has been included as part of the index procedure.Other authors have mentioned this as well.17,18 Al-though this empirically makes sense, our study is thefirst to evaluate and support this hypothesis objectively.Our results demonstrate improved motion, with 87% to97% of normal flexion and extension restored whentriquetral excision was coupled with distal scaphoidpole excision after simulated RSL fusion. Perhaps moreimportantly with regard to the preservation of the dartthrower’s axis, 119% to 137% of normal radial-ulnarmotion was restored. Thus, distal scaphoid pole exci-sion seems to improve the postfusion flexion-extensionarc, whereas triquetral excision has a greater effect onradial-ulnar motion.

Removal of both the triquetrum and distal scaphoidconverts the complex midcarpal joint into a simple balland socket joint. Distal row instability could be a the-oretical concern, but the bones of the distal row aretightly bound and removal of supportive proximalbones should not jeopardize this relationship. Thiswould be analogous to a proximal row carpectomy,where all the bones of the proximal row are removedand distal carpal instability is not a reported problem.20

We observed no distal row instability in any of our testspecimens, all of which were stressed under live fluo-roscopy to check for instability. Finally, much as re-moving the distal pole of the scaphoid decreases thelever arm and subsequent stresses at the radioscaphoidarthrodesis,2 triquetral excision may unload rotationalforces on the lunate and the radiolunate arthrodesis.

As with all cadaver studies, we cannot estimate theeffects of soft tissue responses such as scar tissue for-mation, connective tissue stiffness, and residual swell-ing. Because of this, our study may overestimate gainsin motion that could be expected clinically. Further-more, the excessive dissection associated with bothtriquetral and distal scaphoid excision may have unex-

pected effects on the vascularity of the lunate (or even

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TRIQUETRAL AND DISTAL SCAPHOID POLE EXCISION 837

proximal scaphoid) which could affect fusion rates. Inaddition, the triquetrum and its ligamentous attach-ments are richly innervated by sensory nerve fibers andmight have a role in neuromuscular stabilization on theulnar aspect of the wrist,21 a role that might be jeopar-dized by excision. Further in vivo investigations will benecessary to determine whether this will be a problemin a clinical setting. Pending these investigations beforewidespread adoption of this technique modification, thedemonstrated increases in motion seen in the cadavermodel when distal scaphoid pole and triquetral exci-sions are included with RSL fusion are encouraging.

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