- Email: [email protected]
The Biomechanical Consequences of Trapeziectomy and Partial Trapezoidectomy in the Treatment of Thumb Carpometacarpal and Scaphotrapeziotrapezoid Arthritis
SCIENTIFIC ARTICLE
The Biomechanical Consequences of Trapeziectomy and Partial Trapezoidectomy in the Treatment of Thumb Carpometacarpal and Scaphotrapeziotrapezoid Arthritis Noor Alolabi, MD,* Alexander W. Hooke, MA,† Sanjeev Kakar, MD*
Purpose To determine, using a biomechanical cadaveric model, whether, in the treatment of thumb carpometacarpal and scaphotrapeziotrapezoid arthritis, partial trapezoid resection following trapeziectomy causes carpal, specifically lunocapitate and scapholunate, instability. Materials and methods Eight fresh-frozen mid-forearm cadaver specimens with type I lunates and devoid of basilar thumb arthritis were used in the study. Specimens were mounted onto a wrist simulator applying cyclical wrist flexion/extension and radial/ulnar deviation motions. Carpal kinematics, specifically lunocapitate and scapholunate joint relationships, were measured at 4 different conditions: (1) a native intact state, (2) after trapeziectomy, (3) after 2-mm partial trapezoid resection, and (4) after 4-mm partial trapezoid resection. Results During both flexion/extension and radial/ulnar deviation of the wrist, the lunocapitate and scapholunate joint relationship did not show any notable change following any of trapeziectomy, 2mm, or 4-mm trapezoid resection compared with the intact state. Changes to the lunocapitate and scapholunate angles were clinically insignificant—a maximum of 6 and 4 change, respectively. Conclusions This biomechanical cadaveric study shows that performing a trapeziectomy followed by up to 4 mm of proximal trapezoid resection has a negligible effect upon carpal, specifically lunocapitate and scapholunate, stability. Further research is needed to elucidate the long-term clinical consequences of limited trapezoid resection in vivo. Clinical relevance There may be no clinically relevant effects of resection of up to 4 mm of trapezoid in the surgical management of combined basilar thumb and scaphotrapeziotrapezoid arthritis. (J Hand Surg Am. 2019;-(-):1.e1-e7. Copyright Ó 2019 by the American Society for Surgery of the Hand. All rights reserved.) Key words Trapezoidectomy, trapeziectomy, pantrapezial arthritis, thumb arthritis, carpal instability.
T
(CMC) joint arthritis is a very common cause of pain and dysfunction. A classification system by Eaton et al1 describes 4 stages of thumb basal joint arthritis, HUMB CARPOMETACARPAL
From the *Department of Orthopedic Surgery, Division of Hand and Microvascular Surgery; and the †Materials and Structural Testing Core, Mayo Clinic, Rochester, MN. Received for publication August 29, 2018; accepted in revised form June 28, 2019. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
with the final stage involving combined CMC and scaphotrapeziotrapezoid (STT) joint arthritis. Scaphotrapeziotrapezoid joint arthritis may be involved in up to 62% of patients with first CMC joint Corresponding author: Sanjeev Kakar, MD, Department of Orthopaedic Surgery, Division of Hand Surgery, Mayo Clinic, 200 1st St. SW, Rochester, MN 55905; e-mail: Kakar.Sanjeev@ mayo.edu. 0363-5023/19/---0001$36.00/0 https://doi.org/10.1016/j.jhsa.2019.06.015
Ó 2019 ASSH
r
Published by Elsevier, Inc. All rights reserved.
r
1.e1
1.e2
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
arthritis.2 If STT joint arthritis is left untreated following treatment of CMC arthritis, it may be a source of continued pain.3 Whereas a substantial amount of evidence is available for the treatment of CMC degenerative disease, little has been written on the treatment of concomitant scaphotrapezoid arthritis. Historically, treatment of isolated STT arthritis has included arthrodesis or distal scaphoid excision. When combined with first CMC arthritis, however, treatment commonly involves a partial proximal trapezoid resection, with or without partial distal scaphoid resection.2e8 Although this has been shown to be effective for pain relief, studies have demonstrated possible symptomatic carpal instability.9,10 Such instability could later result in arthritic changes and, ultimately, pain. The biomechanical consequences of partial trapezoid resection following trapezium excision arthroplasty for combined first CMC and STT joint arthritis are poorly understood. We hypothesize that performing a trapeziectomy and partial trapezoid resection does not result in carpal instability. The purpose of this study was to determine the effect of partial trapezoid resection following trapeziectomy on carpal, specifically lunocapitate and scapholunate, stability using a biomechanical cadaveric model.
table using a vicelike clamp on the hand (stationary) while the distal forearm was mounted via K-wires passing through the radius and ulna to a motor-driven stage that moves to create the desired wrist motion. A stepper motor connected to the stage via timing belt pulleys rotates the stage through the desired arc of motion. A mild compressive force (15 N) was statically applied across the wrist using 4 pneumatic actuators sutured to the 5 tendons: FCU, FCR, ECU, and ECRL/ ECRB. The combination of the hand being mounted to an unconstrained X-Y stage and pneumatic muscle loading enabled the cadaveric limb to move about the desired axis of rotation in an unconstrained manner, similar to what would be experienced in vivo. Cyclical motion evaluation Each of the 8 specimens was tested under a series of 4 conditions: (1) a native, intact state (Intact), (2) after trapeziectomy (eTrapezium), (3) after 2-mm (w20%) partial trapezoid resection (2-mm Trapezoid), and (4) after 4-mm (w40%) partial trapezoid resection (4-mm Trapezoid). Owing to the progressive nature of these procedures, their order was not randomized between specimens. Within each condition, the specimen was evaluated via cyclical testing about 2 functional axes of motion, flexion/extension and radial/ulnar deviation. The wrist underwent 100 cycles for each axis of motion driven by the mechanized movement of the forearm. The hand was cycled through each motion cycle at approximately 70 /s. The position and orientation of the hand (tracked via a sensor on the third metacarpal), scaphoid, lunate, capitate, and forearm (tracked via a sensor on the radius) were recorded at 60 Hz using motion capture software (The Motion Monitor;, Innovative Sports Training, Inc., Chicago, IL) for the final 5 cycles of motion. After each 100-cycle evaluation, the wrist was repositioned on the simulator to accommodate the next functional motion to be evaluated. Upon completion of cyclical testing about each of the flexion/extension and radial/ulnar deviation motions, the wrist sequentially underwent the 3 procedures of interest. The maximum wrist motion required for daily activities has been shown to be 60 extension, 54 flexion, 40 ulnar deviation, and 17 radial deviation with the majority of functional tasks falling within a range of 40 each of wrist flexion and extension, and 40 of combined radial/ulnar deviation.12 With this in mind, we targeted 120 of combined wrist flexion/ extension, and 60 of combined radial/ulnar deviation to create a functional evaluation while minimizing the risk of a test-order confounding effect.
MATERIALS AND METHODS Specimen preparation After institutional review board approval, a sample of convenience of 8 fresh-frozen mid-forearm cadaver specimens with type I lunates and no signs of arthritis (as determined by fluoroscopy), were chosen for use in the study. Custom sensor mounts utilizing suture anchors and pins were placed percutaneously under fluoroscopy into the dorsal scaphoid, lunate, capitate, third metacarpal, and radius to use for rigid fixation of motion tracking sensors. Superficial tissue was removed in the proximal forearm and a set of four tendons—flexor carpi ulnaris (FCU), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), and extensor carpi radialis longus and brevis (ECRL/ ECRB) stitched together—were prepared with sutures to allow static loading during testing (Figs, 1, 2). Wrist simulator A wrist simulator was used to move the wrist through a cyclical motion about a single axis of rotation under displacement control.11 Cyclical motion about the flexion/extension and radial/ulnar deviation axes was separately performed. For all tested motions, the specimen was mounted to a small, unconstrained X-Y J Hand Surg Am.
r
Vol. -, - 2019
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
1.e3
FIGURE 1: Sample specimen with motion trackers mounted to a wrist stimulator for wrist radial/ulnar deviation motion.
FIGURE 2: Sample specimen with motion trackers mounted to a wrist stimulator for wrist flexion/extension motion.
Kinematics and data analysis Kinematic motion was captured using a combination of Moiré Phase Tracking 3-dimensional motion tracking sensor hardware (MPT; Metria Innovation, Inc., Milwaukee, WI) and motion capture software (The Motion Monitor) to evaluate the hand, wrist, and forearm kinematics. This device enables measurement of the 3-dimensional position and orientation of sensors attached to the bones relative to an absolute coordinate system generated by a single camera. The position and orientation accuracy of the system are 0.4 mm and 0.05 , respectively. These were rigidly mounted to the radius, third metacarpal, capitate, lunate, and scaphoid. The anatomical coordinate systems of the hand and forearm were defined using a calibrated digitizing stylus according to the International Society of Biomechanics standards.13 The coordinate systems of the capitate, lunate, and scaphoid were aligned to that of the hand (tracked via the third metacarpal sensor) with the wrist in the J Hand Surg Am.
neutral position. Euler angles were then computed with the rotation sequence about the mediolateral (flexion/extension), anterior-posterior (radial/ulnar deviation), and superior-inferior (pronation/supination) axes.
Surgical technique A 5-cm dorsal longitudinal incision overlying the thumb CMC joint was made and the interval between the abductor pollicis longus and extensor pollicis brevis was identified. The CMC joint dorsal capsule was incised longitudinally and the trapezium was fully exposed and released circumferentially. The trapezium was excised en bloc or in a piecemeal fashion with care taken to protect the underlying FCR tendon. A partial trapezoid resection, taking out 2 mm (w20%) followed by another 2 mm, was then performed using an osteotome with care taken to protect the adjacent capitate. r
Vol. -, - 2019
1.e4
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
Data analysis The last 5 of the 100 cycles performed were averaged and used for kinematic analysis. In an effort to evaluate for midcarpal instability, lunocapitate kinematics were evaluated during wrist flexion/extension and radial/ulnar deviation motions for each of the 4 conditions. We also similarly evaluated the scapholunate relationship for each condition. Lunocapitate and scapholunate angles were computed at 5 intervals of both flexion/ extension and radial/ulnar deviation axes. The intercarpal motion about both axes was analyzed for all wrist conditions. The differences between wrist conditions at each 5 interval were analyzed. RESULTS Lunocapitate kinematics During 120 arc of wrist flexion/extension, the lunocapitate joint experienced 40 arc of flexion/ extension motion (Fig. 3) and 20 arc of radial/ulnar deviation (Fig. 4). Compared with the intact state, the flexion/extension relationship of the lunocapitate joint during wrist flexion/extension motion did not change when a trapeziectomy was performed. After both 2-mm and 4-mm trapezoid resection, a 5 increase in extension of the joint was shown. The radial/ulnar deviation relationship of the joint was the same after a trapeziectomy or a 4-mm trapezoid resection, compared with the intact state. Following the 2-mm trapezoid resection, a 2 shift of ulnar deviation was illustrated. The lunocapitate joint experienced a 25 arc of radial/ulnar axial motion (Fig. 5) and a 20 arc of flexion/extension axial motion (Fig. 6) in a 65 arc of wrist radial/ulnar deviation. Both the trapeziectomy and the 2-mm trapezoid resection shifted the lunocapitate joint up to 6 in the ulnar direction, and the 4-mm trapezoid resection shifted the joint in the radial direction 2 . The difference in the lunocapitate joint relationship between the 2-mm and the 4-mm resections was at its greatest (8 ) when the wrist was in 30 of ulnar deviation. In the flexion/extension axis, the trapeziectomy shifted the lunocapitate joint into 2 more flexion during wrist radial/ulnar deviation motion versus the intact position. The 2-mm and 4-mm trapezoid resections maintained a similar position to that of the intact state.
FIGURE 3: Lunocapitate joint angle about the flexion/extension axis during wrist flexion/extension. Error bars represent SD.
trapeziectomy shifted the joint into 2 of increased flexion, and the 2-mm and 4-mm trapezoid resections resulted in 2 to 4 of increased flexion. There was minimal difference between the 2 trapezoid resection conditions for the majority (40 flexion to 50 extension) of the wrist arc of motion. In the radial/ ulnar axis, the trapeziectomy, 2-mm, and 4-mm trapezoid resection conditions all resulted in shifts of under 2 of the joint compared with the intact state. Although following a similar pattern of motion, the 2mm and 4-mm trapezoid resection conditions shifted the joint approximately 2 more radially than the trapeziectomy did. During 60 arc of wrist radial/ulnar deviation, 8 of both radial/ulnar deviation (Fig. 9) and flexion/ extension (Fig. 10) motions were seen in the scapholunate joint. All of trapeziectomy, 2-mm, and 4mm trapezoid resection conditions resulted in a radial shift of 1 to 4 of the joint, with the 4-mm resection showing 1 to 2 higher shift than the other 2 conditions, especially in increased wrist radial deviation. All 3 conditions shifted the scapholunate joint into 4 to 6 greater flexion. DISCUSSION The prevalence of STT arthritis has been reported to be as high as 46% to 62% in cases of preexisting trapeziometacarpal disease.2,14,15 Tomaino et al2 reported on 37 patients who underwent trapezium excision arthroplasty, having addressed the presence of concomitant STT arthritis in 23 patients with performing a proximal trapezoid excision of approximately 2 mm. No increased morbidity was associated with the partial
Scapholunate kinematics The scapholunate joint experienced 30 of flexion/ extension (Fig. 7) and 10 of radial/ulnar deviation arcs (Fig. 8) during 120 arc of wrist flexion/extension. Compared with the intact state, the J Hand Surg Am.
r
Vol. -, - 2019
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
1.e5
FIGURE 4: Lunocapitate joint angle about the radial/ulnar deviation axis during wrist flexion/extension. Error bars represent SD.
FIGURE 6: Lunocapitate joint angle about the flexion/extension axis during wrist radial/ulnar deviation. Error bars represent SD.
FIGURE 5: Lunocapitate joint angle about the radial/ulnar deviation axis during wrist radial/ulnar deviation. Error bars represent SD.
FIGURE 7: Scapholunate joint angle about the flexion/extension axis during wrist flexion/extension. Error bars represent SD.
trapezoid resection and both procedures yielded similar grip and pinch strengths. However, the authors did not specifically examine for carpal instability. In a biomechanical cadaveric study, Wright et al16 showed that resection of 50% of the trapezoid after trapeziectomy for the treatment of combined first CMC and scaphotrapezoid arthritis did not result in proximal migration of the second metacarpal. However, when a complete trapezoidectomy was performed, the index metacarpal did migrate proximally, although only by 1 mm. Despite the results of the previous 2 reports showing no increased morbidity, there is still concern that performing a proximal trapezoid resection in conjunction with a trapeziectomy may result in carpal instability. Rectenwald et al9 reported on 2 patients
developing symptomatic nondissociative dorsal intercalated segment instability (DISI) collapse after trapeziectomy and resection of proximal half of the trapezoid for pantrapezial arthritis. They concluded that ligamentous compromise maybe related to the amount of trapezoid resected. Yuan et al17 reported that the frequency of DISI after trapeziectomy alone increased from 27% before surgery to 50% after surgery. The incidence of DISI in patients who had concomitant STT was even higher at 62% after surgery. They concluded that patients with pantrapezial arthritis are more likely to progress to instability after surgery. It should be noted, however, that this study included 33 patients over a 7-year period. The study’s conclusions are
J Hand Surg Am.
r
Vol. -, - 2019
1.e6
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
FIGURE 8: Scapholunate joint angle about the radial/ulnar deviation axis during wrist flexion/extension. Error bars represent SD.
FIGURE 10: Scapholunate joint angle about the flexion/extension axis during wrist radial/ulnar deviation. Error bars represent SD.
FIGURE 9: Scapholunate joint angle about the radial/ulnar deviation axis during wrist radial/ulnar deviation. Error bars represent SD.
resection, and a trapeziectomy and 4-mm proximal trapezoid resection did not result in any meaningful carpal instability. The maximum change in lunocapitate and scapholunate angles were 6 and 8 , respectively, which may be of little clinical significance. Normal variance in scapholunate angle is approximately 6 with wrist radial/ulnar deviation.20 Moreover, when considering DISI and volar intercalated segmental instability deformities, a change of greater than 30 from normal variance is thought to be of significance, again showing that the differences observed in this study are probably of little clinical significance. The goal of partial trapezoid resection is to relieve contact between the proximal trapezoid and the distal scaphoid on loading. This can usually be achieved with minimal resection of approximately 2 to 4 mm. Depending on the size of the patient’s hand, 4 mm equates to approximately 40% to 60% of the trapezoid. The model showed minimal differences between 2 mm and 4 mm of trapezoid resection. As with any biomechanical study, there are some limitations. The normal physiological loading of the thumb and the wrist is intricate and complex. Dartthrower’s motion, where the wrist is moved from extension and radial deviation to flexion and ulnar deviation, is an important type of wrist movement to measure because it is believed to provide a stable platform for the generation of force and accuracy during power and precision grip activities.21 Our model did not specifically test for this but did include the motions seen with dart-throwers, namely wrist flexion/extension and radial/ulnar deviation, separately. It is difficult to say with certainty whether the
echoed by Tay et al18 who noted that STT arthritis occasionally presents with a DISI pattern, but that it was unclear whether patients are predisposed to the instability secondary to the arthritis or whether the instability causes it. Ferris et al19 surveyed 697 wrist radiographs of patients over 50 years and found a likely association of static DISI occurring as a consequence of STT osteoarthritis. This study’s biomechanical model examined the lunocapitate and scapholunate relationships, specifically looking for evidence of carpal instability at 4 different sequential conditions. Overall, the results showed that performing a trapeziectomy alone, a trapeziectomy and 2-mm proximal trapezoid J Hand Surg Am.
r
Vol. -, - 2019
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
combined motions would have resulted in differing data but, given the very small changes we observed, we do not think that is likely. Second, the sequence of the 4 conditions tested could not be randomized owing to the progressive nature of these procedures. Third, a sample size of 8 cadaveric specimens was a sample of convenience. The differences observed were negligible and a statistical analysis was not warranted. Fourth, in the previous clinical studies, surgeries were performed on patients with STT arthritis whereas the cadaver specimens had no signs of arthritis or instability. Furthermore, although normal wrist kinematics were simulated and very accurate and precise motion devices were utilized, because a cadaveric model was used, we cannot state the long-term effects this resection might have with multiple loadings that would occur in vivo. Lastly, biomechanical changes in planes other than ones specifically studied are also not assessed. In conclusion, this study shows that performing a trapeziectomy followed by limited proximal trapezoid resection does not result in lunocapitate or scapholunate instability. Further research is indicated to elucidate the long-term consequences of limited trapezoid resection in vivo.
6. Garcia-Elias M, Lluch A. Partial excision of the scaphoid: is it ever indicated? Hand Clin. 2001;17(4):687e695. 7. Malerich MM, Clifford J, Eaton B, Eaton R, Littler JW. Distal scaphoid excision arthroplasty for the treatment of degenerative arthritis secondary to scaphoid nonunion. J Hand Surg Am. 1999;24(6):1196e1205. 8. Parry JA, Kakar S. Dual mini TightRope suspensionplasty for thumb basilar joint arthritis: a case series. J Hand Surg Am. 2015;40(2): 297e302. 9. Rectenwald JP, Green DP, Dobyns JH. Symptomatic carpal collapse after trapeziectomy and partial trapezoidectomy: report of two cases. J Hand Surg Am. 2005;30(4):706e710. 10. Corbin C, Warwick D. Midcarpal instability after excision arthroplasty for scapho-trapezial-trapezoid (STT) arthritis. J Hand Surg Eur Vol. 2009;34(4):537e538. 11. Kraisarin J, Dennison DG, Berglund LJ, An KH, Shin AY. Biomechanical comparison of three fixation techniques used for four-corner arthrodesis. J Hand Surg Eur Vol. 2011;36(7): 560e567. 12. Ryu J, Palmer AK, Cooney WP. Wrist joint motion. In: An KN, Berger RA, Cooney WP, eds. Biomechanics of the Wrist Joint. New York: Springer-Verlag; 1991:37e60. 13. Wu G, van der Helm FC, Veeger HE, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion—part II: shoulder, elbow, wrist and hand. J Biomech. 2005;38(5):981e992. 14. North ER, Eaton RG. Degenerative joint disease of the trapezium: a comparative radiographic and anatomic study. J Hand Surg Am. 1983;8(2):160e167. 15. Brown GD III, Roh MS, Strauch RJ, Rosenwasser MP, Ateshian GA, Mow VC. Radiography and visual pathology of the osteoarthritic scaphotrapezio-trapezoidal joint, and its relationship to trapeziometacarpal osteoarthritis. J Hand Surg Am. 2003;28(5): 739e743. 16. Wright TW, Thompson J, Conrad BP. Loading of the index metacarpal after trapezial and partial versus complete trapezoid resection. J Hand Surg Am. 2006;31(1):58e62. 17. Yuan BJ, Moran SL, Tay SC, Berger RA. Trapeziectomy and carpal collapse. J Hand Surg Am. 2009;34(2):219e227. 18. Tay SC, Moran SL, Shin AY, Linscheid RL. The clinical implications of scaphotrapezium-trapezoidal arthritis with associated carpal instability. J Hand Surg Am. 2007;32(1):47e54. 19. Ferris BD, Dunnett W, Lavelle JR. An association between scaphotrapezio-trapezoid osteoarthritis and static dorsal intercalated segment instability. J Hand Surg Br. 1994;19(3):338e339. 20. Kobayashi M, Berger RA, Nagy L, et al. Normal kinematics of carpal bones: a three-dimensional analysis of carpal bone motion relative to the radius. J Biomech. 1997;30(8):787e793. 21. Wolfe SW, Crisco JJ, Orr CM, Marzke MW. The dart-throwing motion of the wrist: is it unique to humans? J Hand Surg Am. 2006;31(9):1429e1437.
REFERENCES 1. Eaton RG, Glickel SZ, Littler JW. Tendon interposition arthroplasty for degenerative arthritis of the trapeziometacarpal joint of the thumb. J Hand Surg Am. 1985;10(5):645e654. 2. Tomaino MM, Vogt M, Weiser R. Scaphotrapezoid arthritis: prevalence in thumbs undergoing trapezium excision arthroplasty and efficacy of proximal trapezoid excision. J Hand Surg Am. 1999;24(6):1220e1224. 3. Irwin AS, Maffulli N, Chesney RB. Scapho-trapezoid arthritis. A cause of residual pain after arthroplasty of the trapeziometacarpal joint. J Hand Surg Br. 1995;20(3):346e352. 4. Varitimidis SE, Fox RJ, King JA, Taras J, Sotereanos DG. Trapeziometacarpal arthroplasty using the entire flexor carpi radialis tendon. Clin Orthop Relat Res. 2000;370:164e170. 5. Garcia-Elias M, Lluch AL, Farreres A, Castillo F, Saffar PH. Resection of the distal scaphoid for scaphotrapeziotrapezoid osteoarthritis. J Hand Surg Br. 1999;2(4):B:448e452.
J Hand Surg Am.
1.e7
r
Vol. -, - 2019
The Biomechanical Consequences of Trapeziectomy and Partial Trapezoidectomy in the Treatment of Thumb Carpometacarpal and Scaphotrapeziotrapezoid Arthritis Noor Alolabi, MD,* Alexander W. Hooke, MA,† Sanjeev Kakar, MD*
Purpose To determine, using a biomechanical cadaveric model, whether, in the treatment of thumb carpometacarpal and scaphotrapeziotrapezoid arthritis, partial trapezoid resection following trapeziectomy causes carpal, specifically lunocapitate and scapholunate, instability. Materials and methods Eight fresh-frozen mid-forearm cadaver specimens with type I lunates and devoid of basilar thumb arthritis were used in the study. Specimens were mounted onto a wrist simulator applying cyclical wrist flexion/extension and radial/ulnar deviation motions. Carpal kinematics, specifically lunocapitate and scapholunate joint relationships, were measured at 4 different conditions: (1) a native intact state, (2) after trapeziectomy, (3) after 2-mm partial trapezoid resection, and (4) after 4-mm partial trapezoid resection. Results During both flexion/extension and radial/ulnar deviation of the wrist, the lunocapitate and scapholunate joint relationship did not show any notable change following any of trapeziectomy, 2mm, or 4-mm trapezoid resection compared with the intact state. Changes to the lunocapitate and scapholunate angles were clinically insignificant—a maximum of 6 and 4 change, respectively. Conclusions This biomechanical cadaveric study shows that performing a trapeziectomy followed by up to 4 mm of proximal trapezoid resection has a negligible effect upon carpal, specifically lunocapitate and scapholunate, stability. Further research is needed to elucidate the long-term clinical consequences of limited trapezoid resection in vivo. Clinical relevance There may be no clinically relevant effects of resection of up to 4 mm of trapezoid in the surgical management of combined basilar thumb and scaphotrapeziotrapezoid arthritis. (J Hand Surg Am. 2019;-(-):1.e1-e7. Copyright Ó 2019 by the American Society for Surgery of the Hand. All rights reserved.) Key words Trapezoidectomy, trapeziectomy, pantrapezial arthritis, thumb arthritis, carpal instability.
T
(CMC) joint arthritis is a very common cause of pain and dysfunction. A classification system by Eaton et al1 describes 4 stages of thumb basal joint arthritis, HUMB CARPOMETACARPAL
From the *Department of Orthopedic Surgery, Division of Hand and Microvascular Surgery; and the †Materials and Structural Testing Core, Mayo Clinic, Rochester, MN. Received for publication August 29, 2018; accepted in revised form June 28, 2019. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
with the final stage involving combined CMC and scaphotrapeziotrapezoid (STT) joint arthritis. Scaphotrapeziotrapezoid joint arthritis may be involved in up to 62% of patients with first CMC joint Corresponding author: Sanjeev Kakar, MD, Department of Orthopaedic Surgery, Division of Hand Surgery, Mayo Clinic, 200 1st St. SW, Rochester, MN 55905; e-mail: Kakar.Sanjeev@ mayo.edu. 0363-5023/19/---0001$36.00/0 https://doi.org/10.1016/j.jhsa.2019.06.015
Ó 2019 ASSH
r
Published by Elsevier, Inc. All rights reserved.
r
1.e1
1.e2
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
arthritis.2 If STT joint arthritis is left untreated following treatment of CMC arthritis, it may be a source of continued pain.3 Whereas a substantial amount of evidence is available for the treatment of CMC degenerative disease, little has been written on the treatment of concomitant scaphotrapezoid arthritis. Historically, treatment of isolated STT arthritis has included arthrodesis or distal scaphoid excision. When combined with first CMC arthritis, however, treatment commonly involves a partial proximal trapezoid resection, with or without partial distal scaphoid resection.2e8 Although this has been shown to be effective for pain relief, studies have demonstrated possible symptomatic carpal instability.9,10 Such instability could later result in arthritic changes and, ultimately, pain. The biomechanical consequences of partial trapezoid resection following trapezium excision arthroplasty for combined first CMC and STT joint arthritis are poorly understood. We hypothesize that performing a trapeziectomy and partial trapezoid resection does not result in carpal instability. The purpose of this study was to determine the effect of partial trapezoid resection following trapeziectomy on carpal, specifically lunocapitate and scapholunate, stability using a biomechanical cadaveric model.
table using a vicelike clamp on the hand (stationary) while the distal forearm was mounted via K-wires passing through the radius and ulna to a motor-driven stage that moves to create the desired wrist motion. A stepper motor connected to the stage via timing belt pulleys rotates the stage through the desired arc of motion. A mild compressive force (15 N) was statically applied across the wrist using 4 pneumatic actuators sutured to the 5 tendons: FCU, FCR, ECU, and ECRL/ ECRB. The combination of the hand being mounted to an unconstrained X-Y stage and pneumatic muscle loading enabled the cadaveric limb to move about the desired axis of rotation in an unconstrained manner, similar to what would be experienced in vivo. Cyclical motion evaluation Each of the 8 specimens was tested under a series of 4 conditions: (1) a native, intact state (Intact), (2) after trapeziectomy (eTrapezium), (3) after 2-mm (w20%) partial trapezoid resection (2-mm Trapezoid), and (4) after 4-mm (w40%) partial trapezoid resection (4-mm Trapezoid). Owing to the progressive nature of these procedures, their order was not randomized between specimens. Within each condition, the specimen was evaluated via cyclical testing about 2 functional axes of motion, flexion/extension and radial/ulnar deviation. The wrist underwent 100 cycles for each axis of motion driven by the mechanized movement of the forearm. The hand was cycled through each motion cycle at approximately 70 /s. The position and orientation of the hand (tracked via a sensor on the third metacarpal), scaphoid, lunate, capitate, and forearm (tracked via a sensor on the radius) were recorded at 60 Hz using motion capture software (The Motion Monitor;, Innovative Sports Training, Inc., Chicago, IL) for the final 5 cycles of motion. After each 100-cycle evaluation, the wrist was repositioned on the simulator to accommodate the next functional motion to be evaluated. Upon completion of cyclical testing about each of the flexion/extension and radial/ulnar deviation motions, the wrist sequentially underwent the 3 procedures of interest. The maximum wrist motion required for daily activities has been shown to be 60 extension, 54 flexion, 40 ulnar deviation, and 17 radial deviation with the majority of functional tasks falling within a range of 40 each of wrist flexion and extension, and 40 of combined radial/ulnar deviation.12 With this in mind, we targeted 120 of combined wrist flexion/ extension, and 60 of combined radial/ulnar deviation to create a functional evaluation while minimizing the risk of a test-order confounding effect.
MATERIALS AND METHODS Specimen preparation After institutional review board approval, a sample of convenience of 8 fresh-frozen mid-forearm cadaver specimens with type I lunates and no signs of arthritis (as determined by fluoroscopy), were chosen for use in the study. Custom sensor mounts utilizing suture anchors and pins were placed percutaneously under fluoroscopy into the dorsal scaphoid, lunate, capitate, third metacarpal, and radius to use for rigid fixation of motion tracking sensors. Superficial tissue was removed in the proximal forearm and a set of four tendons—flexor carpi ulnaris (FCU), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), and extensor carpi radialis longus and brevis (ECRL/ ECRB) stitched together—were prepared with sutures to allow static loading during testing (Figs, 1, 2). Wrist simulator A wrist simulator was used to move the wrist through a cyclical motion about a single axis of rotation under displacement control.11 Cyclical motion about the flexion/extension and radial/ulnar deviation axes was separately performed. For all tested motions, the specimen was mounted to a small, unconstrained X-Y J Hand Surg Am.
r
Vol. -, - 2019
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
1.e3
FIGURE 1: Sample specimen with motion trackers mounted to a wrist stimulator for wrist radial/ulnar deviation motion.
FIGURE 2: Sample specimen with motion trackers mounted to a wrist stimulator for wrist flexion/extension motion.
Kinematics and data analysis Kinematic motion was captured using a combination of Moiré Phase Tracking 3-dimensional motion tracking sensor hardware (MPT; Metria Innovation, Inc., Milwaukee, WI) and motion capture software (The Motion Monitor) to evaluate the hand, wrist, and forearm kinematics. This device enables measurement of the 3-dimensional position and orientation of sensors attached to the bones relative to an absolute coordinate system generated by a single camera. The position and orientation accuracy of the system are 0.4 mm and 0.05 , respectively. These were rigidly mounted to the radius, third metacarpal, capitate, lunate, and scaphoid. The anatomical coordinate systems of the hand and forearm were defined using a calibrated digitizing stylus according to the International Society of Biomechanics standards.13 The coordinate systems of the capitate, lunate, and scaphoid were aligned to that of the hand (tracked via the third metacarpal sensor) with the wrist in the J Hand Surg Am.
neutral position. Euler angles were then computed with the rotation sequence about the mediolateral (flexion/extension), anterior-posterior (radial/ulnar deviation), and superior-inferior (pronation/supination) axes.
Surgical technique A 5-cm dorsal longitudinal incision overlying the thumb CMC joint was made and the interval between the abductor pollicis longus and extensor pollicis brevis was identified. The CMC joint dorsal capsule was incised longitudinally and the trapezium was fully exposed and released circumferentially. The trapezium was excised en bloc or in a piecemeal fashion with care taken to protect the underlying FCR tendon. A partial trapezoid resection, taking out 2 mm (w20%) followed by another 2 mm, was then performed using an osteotome with care taken to protect the adjacent capitate. r
Vol. -, - 2019
1.e4
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
Data analysis The last 5 of the 100 cycles performed were averaged and used for kinematic analysis. In an effort to evaluate for midcarpal instability, lunocapitate kinematics were evaluated during wrist flexion/extension and radial/ulnar deviation motions for each of the 4 conditions. We also similarly evaluated the scapholunate relationship for each condition. Lunocapitate and scapholunate angles were computed at 5 intervals of both flexion/ extension and radial/ulnar deviation axes. The intercarpal motion about both axes was analyzed for all wrist conditions. The differences between wrist conditions at each 5 interval were analyzed. RESULTS Lunocapitate kinematics During 120 arc of wrist flexion/extension, the lunocapitate joint experienced 40 arc of flexion/ extension motion (Fig. 3) and 20 arc of radial/ulnar deviation (Fig. 4). Compared with the intact state, the flexion/extension relationship of the lunocapitate joint during wrist flexion/extension motion did not change when a trapeziectomy was performed. After both 2-mm and 4-mm trapezoid resection, a 5 increase in extension of the joint was shown. The radial/ulnar deviation relationship of the joint was the same after a trapeziectomy or a 4-mm trapezoid resection, compared with the intact state. Following the 2-mm trapezoid resection, a 2 shift of ulnar deviation was illustrated. The lunocapitate joint experienced a 25 arc of radial/ulnar axial motion (Fig. 5) and a 20 arc of flexion/extension axial motion (Fig. 6) in a 65 arc of wrist radial/ulnar deviation. Both the trapeziectomy and the 2-mm trapezoid resection shifted the lunocapitate joint up to 6 in the ulnar direction, and the 4-mm trapezoid resection shifted the joint in the radial direction 2 . The difference in the lunocapitate joint relationship between the 2-mm and the 4-mm resections was at its greatest (8 ) when the wrist was in 30 of ulnar deviation. In the flexion/extension axis, the trapeziectomy shifted the lunocapitate joint into 2 more flexion during wrist radial/ulnar deviation motion versus the intact position. The 2-mm and 4-mm trapezoid resections maintained a similar position to that of the intact state.
FIGURE 3: Lunocapitate joint angle about the flexion/extension axis during wrist flexion/extension. Error bars represent SD.
trapeziectomy shifted the joint into 2 of increased flexion, and the 2-mm and 4-mm trapezoid resections resulted in 2 to 4 of increased flexion. There was minimal difference between the 2 trapezoid resection conditions for the majority (40 flexion to 50 extension) of the wrist arc of motion. In the radial/ ulnar axis, the trapeziectomy, 2-mm, and 4-mm trapezoid resection conditions all resulted in shifts of under 2 of the joint compared with the intact state. Although following a similar pattern of motion, the 2mm and 4-mm trapezoid resection conditions shifted the joint approximately 2 more radially than the trapeziectomy did. During 60 arc of wrist radial/ulnar deviation, 8 of both radial/ulnar deviation (Fig. 9) and flexion/ extension (Fig. 10) motions were seen in the scapholunate joint. All of trapeziectomy, 2-mm, and 4mm trapezoid resection conditions resulted in a radial shift of 1 to 4 of the joint, with the 4-mm resection showing 1 to 2 higher shift than the other 2 conditions, especially in increased wrist radial deviation. All 3 conditions shifted the scapholunate joint into 4 to 6 greater flexion. DISCUSSION The prevalence of STT arthritis has been reported to be as high as 46% to 62% in cases of preexisting trapeziometacarpal disease.2,14,15 Tomaino et al2 reported on 37 patients who underwent trapezium excision arthroplasty, having addressed the presence of concomitant STT arthritis in 23 patients with performing a proximal trapezoid excision of approximately 2 mm. No increased morbidity was associated with the partial
Scapholunate kinematics The scapholunate joint experienced 30 of flexion/ extension (Fig. 7) and 10 of radial/ulnar deviation arcs (Fig. 8) during 120 arc of wrist flexion/extension. Compared with the intact state, the J Hand Surg Am.
r
Vol. -, - 2019
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
1.e5
FIGURE 4: Lunocapitate joint angle about the radial/ulnar deviation axis during wrist flexion/extension. Error bars represent SD.
FIGURE 6: Lunocapitate joint angle about the flexion/extension axis during wrist radial/ulnar deviation. Error bars represent SD.
FIGURE 5: Lunocapitate joint angle about the radial/ulnar deviation axis during wrist radial/ulnar deviation. Error bars represent SD.
FIGURE 7: Scapholunate joint angle about the flexion/extension axis during wrist flexion/extension. Error bars represent SD.
trapezoid resection and both procedures yielded similar grip and pinch strengths. However, the authors did not specifically examine for carpal instability. In a biomechanical cadaveric study, Wright et al16 showed that resection of 50% of the trapezoid after trapeziectomy for the treatment of combined first CMC and scaphotrapezoid arthritis did not result in proximal migration of the second metacarpal. However, when a complete trapezoidectomy was performed, the index metacarpal did migrate proximally, although only by 1 mm. Despite the results of the previous 2 reports showing no increased morbidity, there is still concern that performing a proximal trapezoid resection in conjunction with a trapeziectomy may result in carpal instability. Rectenwald et al9 reported on 2 patients
developing symptomatic nondissociative dorsal intercalated segment instability (DISI) collapse after trapeziectomy and resection of proximal half of the trapezoid for pantrapezial arthritis. They concluded that ligamentous compromise maybe related to the amount of trapezoid resected. Yuan et al17 reported that the frequency of DISI after trapeziectomy alone increased from 27% before surgery to 50% after surgery. The incidence of DISI in patients who had concomitant STT was even higher at 62% after surgery. They concluded that patients with pantrapezial arthritis are more likely to progress to instability after surgery. It should be noted, however, that this study included 33 patients over a 7-year period. The study’s conclusions are
J Hand Surg Am.
r
Vol. -, - 2019
1.e6
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
FIGURE 8: Scapholunate joint angle about the radial/ulnar deviation axis during wrist flexion/extension. Error bars represent SD.
FIGURE 10: Scapholunate joint angle about the flexion/extension axis during wrist radial/ulnar deviation. Error bars represent SD.
FIGURE 9: Scapholunate joint angle about the radial/ulnar deviation axis during wrist radial/ulnar deviation. Error bars represent SD.
resection, and a trapeziectomy and 4-mm proximal trapezoid resection did not result in any meaningful carpal instability. The maximum change in lunocapitate and scapholunate angles were 6 and 8 , respectively, which may be of little clinical significance. Normal variance in scapholunate angle is approximately 6 with wrist radial/ulnar deviation.20 Moreover, when considering DISI and volar intercalated segmental instability deformities, a change of greater than 30 from normal variance is thought to be of significance, again showing that the differences observed in this study are probably of little clinical significance. The goal of partial trapezoid resection is to relieve contact between the proximal trapezoid and the distal scaphoid on loading. This can usually be achieved with minimal resection of approximately 2 to 4 mm. Depending on the size of the patient’s hand, 4 mm equates to approximately 40% to 60% of the trapezoid. The model showed minimal differences between 2 mm and 4 mm of trapezoid resection. As with any biomechanical study, there are some limitations. The normal physiological loading of the thumb and the wrist is intricate and complex. Dartthrower’s motion, where the wrist is moved from extension and radial deviation to flexion and ulnar deviation, is an important type of wrist movement to measure because it is believed to provide a stable platform for the generation of force and accuracy during power and precision grip activities.21 Our model did not specifically test for this but did include the motions seen with dart-throwers, namely wrist flexion/extension and radial/ulnar deviation, separately. It is difficult to say with certainty whether the
echoed by Tay et al18 who noted that STT arthritis occasionally presents with a DISI pattern, but that it was unclear whether patients are predisposed to the instability secondary to the arthritis or whether the instability causes it. Ferris et al19 surveyed 697 wrist radiographs of patients over 50 years and found a likely association of static DISI occurring as a consequence of STT osteoarthritis. This study’s biomechanical model examined the lunocapitate and scapholunate relationships, specifically looking for evidence of carpal instability at 4 different sequential conditions. Overall, the results showed that performing a trapeziectomy alone, a trapeziectomy and 2-mm proximal trapezoid J Hand Surg Am.
r
Vol. -, - 2019
TRAPEZIECTOMY AND PARTIAL TRAPEZOIDECTOMY
combined motions would have resulted in differing data but, given the very small changes we observed, we do not think that is likely. Second, the sequence of the 4 conditions tested could not be randomized owing to the progressive nature of these procedures. Third, a sample size of 8 cadaveric specimens was a sample of convenience. The differences observed were negligible and a statistical analysis was not warranted. Fourth, in the previous clinical studies, surgeries were performed on patients with STT arthritis whereas the cadaver specimens had no signs of arthritis or instability. Furthermore, although normal wrist kinematics were simulated and very accurate and precise motion devices were utilized, because a cadaveric model was used, we cannot state the long-term effects this resection might have with multiple loadings that would occur in vivo. Lastly, biomechanical changes in planes other than ones specifically studied are also not assessed. In conclusion, this study shows that performing a trapeziectomy followed by limited proximal trapezoid resection does not result in lunocapitate or scapholunate instability. Further research is indicated to elucidate the long-term consequences of limited trapezoid resection in vivo.
6. Garcia-Elias M, Lluch A. Partial excision of the scaphoid: is it ever indicated? Hand Clin. 2001;17(4):687e695. 7. Malerich MM, Clifford J, Eaton B, Eaton R, Littler JW. Distal scaphoid excision arthroplasty for the treatment of degenerative arthritis secondary to scaphoid nonunion. J Hand Surg Am. 1999;24(6):1196e1205. 8. Parry JA, Kakar S. Dual mini TightRope suspensionplasty for thumb basilar joint arthritis: a case series. J Hand Surg Am. 2015;40(2): 297e302. 9. Rectenwald JP, Green DP, Dobyns JH. Symptomatic carpal collapse after trapeziectomy and partial trapezoidectomy: report of two cases. J Hand Surg Am. 2005;30(4):706e710. 10. Corbin C, Warwick D. Midcarpal instability after excision arthroplasty for scapho-trapezial-trapezoid (STT) arthritis. J Hand Surg Eur Vol. 2009;34(4):537e538. 11. Kraisarin J, Dennison DG, Berglund LJ, An KH, Shin AY. Biomechanical comparison of three fixation techniques used for four-corner arthrodesis. J Hand Surg Eur Vol. 2011;36(7): 560e567. 12. Ryu J, Palmer AK, Cooney WP. Wrist joint motion. In: An KN, Berger RA, Cooney WP, eds. Biomechanics of the Wrist Joint. New York: Springer-Verlag; 1991:37e60. 13. Wu G, van der Helm FC, Veeger HE, et al. ISB recommendation on definitions of joint coordinate systems of various joints for the reporting of human joint motion—part II: shoulder, elbow, wrist and hand. J Biomech. 2005;38(5):981e992. 14. North ER, Eaton RG. Degenerative joint disease of the trapezium: a comparative radiographic and anatomic study. J Hand Surg Am. 1983;8(2):160e167. 15. Brown GD III, Roh MS, Strauch RJ, Rosenwasser MP, Ateshian GA, Mow VC. Radiography and visual pathology of the osteoarthritic scaphotrapezio-trapezoidal joint, and its relationship to trapeziometacarpal osteoarthritis. J Hand Surg Am. 2003;28(5): 739e743. 16. Wright TW, Thompson J, Conrad BP. Loading of the index metacarpal after trapezial and partial versus complete trapezoid resection. J Hand Surg Am. 2006;31(1):58e62. 17. Yuan BJ, Moran SL, Tay SC, Berger RA. Trapeziectomy and carpal collapse. J Hand Surg Am. 2009;34(2):219e227. 18. Tay SC, Moran SL, Shin AY, Linscheid RL. The clinical implications of scaphotrapezium-trapezoidal arthritis with associated carpal instability. J Hand Surg Am. 2007;32(1):47e54. 19. Ferris BD, Dunnett W, Lavelle JR. An association between scaphotrapezio-trapezoid osteoarthritis and static dorsal intercalated segment instability. J Hand Surg Br. 1994;19(3):338e339. 20. Kobayashi M, Berger RA, Nagy L, et al. Normal kinematics of carpal bones: a three-dimensional analysis of carpal bone motion relative to the radius. J Biomech. 1997;30(8):787e793. 21. Wolfe SW, Crisco JJ, Orr CM, Marzke MW. The dart-throwing motion of the wrist: is it unique to humans? J Hand Surg Am. 2006;31(9):1429e1437.
REFERENCES 1. Eaton RG, Glickel SZ, Littler JW. Tendon interposition arthroplasty for degenerative arthritis of the trapeziometacarpal joint of the thumb. J Hand Surg Am. 1985;10(5):645e654. 2. Tomaino MM, Vogt M, Weiser R. Scaphotrapezoid arthritis: prevalence in thumbs undergoing trapezium excision arthroplasty and efficacy of proximal trapezoid excision. J Hand Surg Am. 1999;24(6):1220e1224. 3. Irwin AS, Maffulli N, Chesney RB. Scapho-trapezoid arthritis. A cause of residual pain after arthroplasty of the trapeziometacarpal joint. J Hand Surg Br. 1995;20(3):346e352. 4. Varitimidis SE, Fox RJ, King JA, Taras J, Sotereanos DG. Trapeziometacarpal arthroplasty using the entire flexor carpi radialis tendon. Clin Orthop Relat Res. 2000;370:164e170. 5. Garcia-Elias M, Lluch AL, Farreres A, Castillo F, Saffar PH. Resection of the distal scaphoid for scaphotrapeziotrapezoid osteoarthritis. J Hand Surg Br. 1999;2(4):B:448e452.
J Hand Surg Am.
1.e7
r
Vol. -, - 2019