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Partial Trapezoid Excision in Thumb CMC Arthroplasty for STT Arthritis: A Cadaveric Study
SCIENTIFIC ARTICLE
Partial Trapezoid Excision in Thumb CMC Arthroplasty for STT Arthritis: A Cadaveric Study Alex Ferikes, MD,* Gregory Merrell, MD*
Purpose Thumb carpometacarpal (CMC) joint arthroplasty is one of the most commonly performed surgeries by hand surgeons. A large portion of these patients also have scaphotrapezoidal (ST) arthritis in addition to CMC arthritis. The purposes of this study were to quantify the amount of transverse trapezoid resection necessary to prevent ST impingement and to compare an oblique with a transverse osteotomy of the trapezoid. Methods A total of 9 cadaveric specimens were used and were randomly placed into 2 groups. Group 1 had sequential transverse osteotomies and the space between the scaphoid and trapezoid was measured in various wrist positions. Group 2 had oblique osteotomies and the ST distance was measured in multiple wrist positions. Results In group 1, there was no contact between the scaphoid and trapezoid in neutral wrist position after any resection. The half and two-thirds transverse osteotomies did not have contact at 20 radial deviation (RD) and 30 wrist flexion (WF). In 1 of the 5 specimens, there was contact at one-third resection in either isolated RD or WF. In 3 specimens, there was contact at one-third resection with 20 of radial deviation combined with 30 WF. In group 2, there was no contact in any specimen in any wrist position tested. At neutral, there was 3.7 mm of space between the scaphoid and trapezoid measured at the radial side. In 20 RD and 0 WF, an average space remaining was 2.8 mm. In 0 RD and 30 WF, there was an average space of 2.3 mm remaining. At 20 RD and 30 WF, there was an average space remaining of 1.8 mm. At the extreme of RD and WF, there was an average space remaining of 1.4 mm. Conclusions An oblique osteotomy of the trapezoid did not have any ST contact in 20 RD and 30 WF. The transverse osteotomies had contact with only one-third resection. Therefore, if a transverse osteotomy of the trapezoid is performed, more than one-third of the bone should be resected to minimize the risk for bony impingement in positions of WF, RD, or both. Clinical relevance In ST arthritis, an oblique osteotomy of the trapezoid may prevent impingement while allowing for less overall bony resection compared with a transverse osteotomy. (J Hand Surg Am. 2019;-(-):1.e1-e4. Copyright Ó 2020 by the American Society for Surgery of the Hand. All rights reserved.) Key words Scaphotrapezial arthritis, trapezoid excision.
From the *Indiana Hand to Shoulder Center, Indianapolis, IN. Received for publication June 11, 2018; accepted in revised form December 4, 2019. G. M. received support from the Indiana Hand Education and Research Fund. The other author declares that he has no relevant conflicts of interest. Corresponding author: Alex Ferikes, MD, Indiana Hand to Shoulder Center, 8501 Harcourt Road, Indianapolis, IN 46260; e-mail: [email protected]. 0363-5023/19/---0001$36.00/0 https://doi.org/10.1016/j.jhsa.2019.12.003
O
carpometacarpal (CMC) joint is common and CMC arthroplasty for this problem is one of the most common procedures performed by hand surgeons. A large proportion of these patients also have scaphotrapezium-trapezoid (STT) arthritis in addition to CMC arthritis.1e7 A previous anatomic study with 393 cadavers, average age 67 years, showed that about 20% of wrists had at least some arthritic changes at STEOARTHRITIS OF THE THUMB
Ó 2020 ASSH
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Published by Elsevier, Inc. All rights reserved.
r
1.e1
1.e2
TRAPEZOID EXCISION IN THUMB CMC ARTHROPLASTY
the STT joint.8 A different cadaveric study in 73 wrists showed that there was evidence of STT arthritis in 83% of specimens.9 Scaphotrapezium-trapezoid arthritis coexisting with CMC arthritis may present similarly in patients with isolated CMC arthritis. Symptoms may include deep aching pain at the base of the thumb and pain with grasping and twisting activities.7 Unidentified and untreated STT arthritis in patients undergoing CMC arthroplasty can lead to persistent pain and potentially cause failure after surgery for basal joint arthritis.5 When faced with scaphotrapezoidal (ST) arthritis while performing a CMC arthroplasty, a decision must be made as to what is necessary to address this issue properly. A previous study1 showed that excising 2 mm from the proximal portion of the trapezoid prevented contact at the ST joint when there was no traction on the fingers. Our objectives in this study were 3-fold: to investigate the amount of trapezoid resection, performed in a transverse fashion, necessary to prevent ST contact with various hand positions; to determine which hand positions were most likely to cause ST contact; and to determine whether an oblique osteotomy would allow for less bone resection while minimizing the risk for ST contact, compared with a transverse osteotomy. Our hypothesis, based on our clinical observations, was that there would be ST contact in positions of radial deviation (RD) and wrist flexion (WF). We also believed that an oblique osteotomy of the trapezoid would minimize the risk for ST impingement while allowing for more preservation of trapezoid bone stock.
FIGURE 1: Intraoperative x-ray of oblique osteotomy (arrowhead) performed of the trapezoid. This was done in conjunction with a CMC arthroplasty.
extensor pollicis brevis and performing a longitudinal capsulotomy. Care was taken to dissect the trapezium carefully from its anatomic position. Once it was removed in its entirety, the ST joint was examined. We scored marks at the one-third, one-half, and twothirds points of the overall height of the trapezoid after we measured these points with a micrometer. Sequential osteotomies were made transversely across the trapezoid, taking one-third and then onehalf and two-thirds of the trapezoid using a straight osteotome. After each resection, the wrist was placed in various positions: 20 RD and wrist neutral, 0 RD and 30 flexion, and 20 RD and 30 flexion, and then finally the wrist was taken through extremes of motion to see at what angle impingement occurred. In the second group, 4 cadavers were dissected. The same surgical approach was employed as in the first group. In these specimens, once the ST joint was reached, an oblique osteotomy was made. The radial side of the osteotomy began at the midpoint of the trapezoid and ended with about 1 mm of ST space on the ulnar side (Fig. 1). Each wrist was then taken through various positions to see at what angles impingement would occur. All measurements were recorded with a micrometer at the radial side of the osteotomy.
MATERIALS AND METHODS We obtained a sample of convenience of 9 cadaveric specimens sectioned at a level proximal to the elbow joint for this study and randomly assigned to 1 of 2 groups. The age of the cadavers ranged from 45 to 88 years (mean age, 66 years). No ST arthritis was noted on gross examination of the specimens. The lead author performed all dissections. In each cadaver, the contact points at the ST joint were observed with RD, WF, or both after resection of one-third of the trapezoid using a transverse cut. The wrists were placed manually in these positions and were measured with a goniometer. The space between the trapezoid and scaphoid increased with either wrist extension or ulnar deviation; therefore, these positions were not measured in the study. In the first group, 5 cadavers were dissected. A standard dorsal approach to the CMC joint was performed, retracting the abductor pollicis longus and J Hand Surg Am.
RESULTS In group 1, there was no contact between the scaphoid and trapezoid in neutral wrist position after any resection. In 1 of the 5 specimens, there was contact after the one-third resection in either isolated r
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TRAPEZOID EXCISION IN THUMB CMC ARTHROPLASTY
None of the two-thirds osteotomies had contact at any wrist position. They had a remaining space averaging 5.0 mm in neutral (range, 4.0e6.9 mm), 3.5 mm in 20 RD and 0 WF (range, 2.4e4.6 mm), 2.9 mm in 0 RD and 30 WF (range, 2.2e4.2 mm), and 2.5 mm in 20 RD and 30 WF (range, 1.7e3.7 mm) (Table 1). In addition, for group 1, we measured the angles of contact for each osteotomy. For the one-third osteotomies, this contact angle averaged 33 RD and 19 WF. In the one-half osteotomies, the first specimen had no contact even at 55 RD and 20 WF; however, the other 4 specimens had an average contact angle of 47 RD and 20 WF. The two-thirds osteotomies had no contact regardless of the wrist position, with an average space at 55 RD and 20 WF of 1.4 mm (range, 0.7e2.5 mm). In group 2, there was no contact in any specimen in any wrist position tested. There was a remaining space averaging 3.7 mm in neutral (range, 2.8e5.0 mm), 2.8 mm in 20 RD and 0 WF (range, 1.6e4.5 mm), 2.3 mm in 0 RD and 30 WF (range, 1.0e3.6 mm), and 1.8 mm in 20 RD and 30 WF (range, 1.0e3.2 mm). We tested the extreme wrist position of 20 RD and 55 WF; there was an average of 1.4 mm space remaining (range, 0.7e2.5 mm) (Table 2).
TABLE 1. Group 1 Results: Increasing Transverse Osteotomies. Raw Data From Each Cadaver in Transverse Osteotomy Group (Measurements in Millimeters of Space Remaining Between Scaphoid and Trapezoid) Extent of Transverse Osteotomy Wrist Position
1/3
1/2
2/3
2.9
5.3
6.9
20 RD, 0 Flex
1.9
2.0
4.4
0 RD, 30 Flex
2.1
2.8
3.3
1.4
1.5
3.0
Neutral
1.5
3.2
5.5
20 RD, 0 Flex
0.5
2.1
4.6
0 RD, 30 Flex
1.2
2.0
4.2
20 RD, 30 Flex
0.4
1.5
3.7
1.4
2.7
4.0
20 RD, 0 Flex
0.5
1.0
2.4
0 RD, 30 Flex
0.3
0.6
2.2
0.5
1.9
Cadaver #1 Neutral
20 RD, 30 Flex Cadaver #2
Cadaver #3 Neutral
20 RD, 30 Flex
Contact
Cadaver #4 Neutral
2.8
4.8
20 RD, 0 Flex
Contact
1.7
1.5
3.1
0 RD, 30 Flex
Contact
1.1
2.5
20 RD, 30 Flex
Contact
0.9
1.7
DISCUSSION Brown et al3 analyzed 69 cadaver thumbs radiographically and visually, noting both CMC and STT arthritis in 60% of specimens. However, radiographs and direct inspection of the STT joint at the time of surgery correlated with the radiographic findings in only 39% of cases. In the one-third osteotomies of group 1, there was an average space remaining of 1.9 mm in a neutral position, yet there was still contact at the ST joint in various wrist positions with 3 of 5 specimens. That amount of resection may be insufficient to prevent ST contact. We found that after a transverse osteotomy, the most likely position of contact at the ST joint is with RD and WF. However, when performing an oblique osteotomy, we noted no points of contact and there was an average of 1.8 mm of space remaining in 20 RD and 30 WF. In addition, there was no contact in any of the group 1 cadavers after resection of one-half the trapezoid. A potential point of concern is proximal migration of the index finger metacarpal after partial removal of the trapezoid. Wright et al6 examined the effects of partial or complete trapezoidectomy in conjunction with trapeziectomy in a cadaveric model. They showed that trapezium
Cadaver #5 Neutral
2.1
3.5
4.6
20 RD, 0 Flex
1.6
2.0
3.3
0 RD, 30 Flex 20 RD, 30 Flex
0.90
1.5
2.6
Contact
0.8
2.3
RD or flexion. In 3 of the 5 specimens, there was contact at one-third resection with 20 RD combined with 30 flexion. In osteotomies in which there was no contact, the remaining space averaged 1.9 mm in neutral (range, 1.4e2.9 mm), 1.1 mm in 20 RD and 0 WF (range, 0.5e1.9 mm), 1.1 mm in 0 RD and 30 WF (range, 0.3e2.1 mm), and 0.9 mm in 20 RD and 30 WF (range, 0.4e1.4 mm). None of the one-half osteotomies had contact at any wrist position. There was a remaining space averaging 3.5 mm in neutral (range, 2.7e5.3 mm), 1.7 mm in 20 RD and 0 WF (range, 1.0e2.1 mm), 1.6 mm in 0 RD and 30 WF (range, 0.6e2.8 mm), and 1.1 mm in 20 RD and 30 WF (range, 0.5e1.5 mm). J Hand Surg Am.
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TABLE 2.
TRAPEZOID EXCISION IN THUMB CMC ARTHROPLASTY
Average Space Remaining for Oblique Osteotomy Group (All Measurements in mm) Wrist Position
Space remaining (range)
Neutral
20 RD, 0 Flex
0 RD, 30 Flex
20 RD, 30 Flex
20 RD, 55 Flex
3.7 (2.8e5.0)
2.8 (1.6e4.5)
2.3 (1.0e3.6)
1.8 (1.0e3.2)
1.4 (0.7e2.5)
excision and partial trapezoidectomy had important effects on the biomechanics of the index metacarpal when loaded longitudinally. They also showed that even when 50% or more of the trapezoid was left, there was still 1 to 2 mm of proximal migration under load. We therefore disagree with the conclusion of Wright et al that a 50% transverse resection would be sufficient. In a neutral wrist position there was more than 3 mm of space, but in positions of WF or RD there is less than 2 mm of space, so proximal migration would put the trapezoid at risk for contact with the scaphoid. In our study, the one-third oblique osteotomy group had an average of 1.8 mm of space remaining, so this may be insufficient under conditions of axial load to prevent ST contact completely. There were limitations to this study. We did not perform tendon loading when performing our measurements; doing so might have changed our findings, likely decreasing the osteotomy space. We also had a limited number of specimens, and these did not have obvious signs of osteoarthritis at either the CMC or ST joints. When performing a transverse osteotomy of the trapezoid, one-half of the trapezoid or more should be resected to minimize contact in positions of RD or WF. If an oblique osteotomy is performed, only the
J Hand Surg Am.
radial half requires excision with a much smaller resection on the ulnar side. REFERENCES 1. 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. 2. Armstrong AL, Hunter JB, Davis TR. The prevalence of degenerative arthritis of the base of the thumb in postmenopausal women. J Hand Surg Br. 1994;19(3):340e341. 3. Brown GC, Roh MS, Strauch RJ, et al. Radiography and visual pathology of the osteoarthritic scaphotrapezio-trapezoidal joint, and its relationship to trapeziometacarpal osteoarthritis. J Hand Surg Am. 2003;28(5):739e743. 4. Barron OA, Catalano LW. Thumb basal joint arthritis. In: Wolfe SWW, Hotchkiss RN, Pederson WC, Kozin SH, eds. Green’s Operative Hand Surgery. 6th ed. Philadelphia, PA: Elsevier; 2011: 417. 5. Irwin AS, Maffulli N, Chesney RB. Scapho-trapezoid arthritis: a cause of residual pain after arthroplasty of the trapezio-metacarpal joint. J Hand Surg Br. 1995;20(3):346e352. 6. 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. 7. Wolf JM. Treatment of scaphotrapezio-trapezoid arthritis. Hand Clin. 2008;24(3):301e306. 8. Moritomo H, Viegas SF, Nakamura K, et al. The scaphotrapeziotrapezoidal joint. Part 1: an anatomic and radiographic study. J Hand Surg Am. 2000;25(5):899e910. 9. Bhatia A, Pisoh T, Touam C, et al. Incidence and distribution of scaphotrapeziotrapezoidal arthritis in 73 fresh cadaveric wrists. Ann Chir Main Memb Super. 1996;15(4):220e225.
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Partial Trapezoid Excision in Thumb CMC Arthroplasty for STT Arthritis: A Cadaveric Study Alex Ferikes, MD,* Gregory Merrell, MD*
Purpose Thumb carpometacarpal (CMC) joint arthroplasty is one of the most commonly performed surgeries by hand surgeons. A large portion of these patients also have scaphotrapezoidal (ST) arthritis in addition to CMC arthritis. The purposes of this study were to quantify the amount of transverse trapezoid resection necessary to prevent ST impingement and to compare an oblique with a transverse osteotomy of the trapezoid. Methods A total of 9 cadaveric specimens were used and were randomly placed into 2 groups. Group 1 had sequential transverse osteotomies and the space between the scaphoid and trapezoid was measured in various wrist positions. Group 2 had oblique osteotomies and the ST distance was measured in multiple wrist positions. Results In group 1, there was no contact between the scaphoid and trapezoid in neutral wrist position after any resection. The half and two-thirds transverse osteotomies did not have contact at 20 radial deviation (RD) and 30 wrist flexion (WF). In 1 of the 5 specimens, there was contact at one-third resection in either isolated RD or WF. In 3 specimens, there was contact at one-third resection with 20 of radial deviation combined with 30 WF. In group 2, there was no contact in any specimen in any wrist position tested. At neutral, there was 3.7 mm of space between the scaphoid and trapezoid measured at the radial side. In 20 RD and 0 WF, an average space remaining was 2.8 mm. In 0 RD and 30 WF, there was an average space of 2.3 mm remaining. At 20 RD and 30 WF, there was an average space remaining of 1.8 mm. At the extreme of RD and WF, there was an average space remaining of 1.4 mm. Conclusions An oblique osteotomy of the trapezoid did not have any ST contact in 20 RD and 30 WF. The transverse osteotomies had contact with only one-third resection. Therefore, if a transverse osteotomy of the trapezoid is performed, more than one-third of the bone should be resected to minimize the risk for bony impingement in positions of WF, RD, or both. Clinical relevance In ST arthritis, an oblique osteotomy of the trapezoid may prevent impingement while allowing for less overall bony resection compared with a transverse osteotomy. (J Hand Surg Am. 2019;-(-):1.e1-e4. Copyright Ó 2020 by the American Society for Surgery of the Hand. All rights reserved.) Key words Scaphotrapezial arthritis, trapezoid excision.
From the *Indiana Hand to Shoulder Center, Indianapolis, IN. Received for publication June 11, 2018; accepted in revised form December 4, 2019. G. M. received support from the Indiana Hand Education and Research Fund. The other author declares that he has no relevant conflicts of interest. Corresponding author: Alex Ferikes, MD, Indiana Hand to Shoulder Center, 8501 Harcourt Road, Indianapolis, IN 46260; e-mail: [email protected]. 0363-5023/19/---0001$36.00/0 https://doi.org/10.1016/j.jhsa.2019.12.003
O
carpometacarpal (CMC) joint is common and CMC arthroplasty for this problem is one of the most common procedures performed by hand surgeons. A large proportion of these patients also have scaphotrapezium-trapezoid (STT) arthritis in addition to CMC arthritis.1e7 A previous anatomic study with 393 cadavers, average age 67 years, showed that about 20% of wrists had at least some arthritic changes at STEOARTHRITIS OF THE THUMB
Ó 2020 ASSH
r
Published by Elsevier, Inc. All rights reserved.
r
1.e1
1.e2
TRAPEZOID EXCISION IN THUMB CMC ARTHROPLASTY
the STT joint.8 A different cadaveric study in 73 wrists showed that there was evidence of STT arthritis in 83% of specimens.9 Scaphotrapezium-trapezoid arthritis coexisting with CMC arthritis may present similarly in patients with isolated CMC arthritis. Symptoms may include deep aching pain at the base of the thumb and pain with grasping and twisting activities.7 Unidentified and untreated STT arthritis in patients undergoing CMC arthroplasty can lead to persistent pain and potentially cause failure after surgery for basal joint arthritis.5 When faced with scaphotrapezoidal (ST) arthritis while performing a CMC arthroplasty, a decision must be made as to what is necessary to address this issue properly. A previous study1 showed that excising 2 mm from the proximal portion of the trapezoid prevented contact at the ST joint when there was no traction on the fingers. Our objectives in this study were 3-fold: to investigate the amount of trapezoid resection, performed in a transverse fashion, necessary to prevent ST contact with various hand positions; to determine which hand positions were most likely to cause ST contact; and to determine whether an oblique osteotomy would allow for less bone resection while minimizing the risk for ST contact, compared with a transverse osteotomy. Our hypothesis, based on our clinical observations, was that there would be ST contact in positions of radial deviation (RD) and wrist flexion (WF). We also believed that an oblique osteotomy of the trapezoid would minimize the risk for ST impingement while allowing for more preservation of trapezoid bone stock.
FIGURE 1: Intraoperative x-ray of oblique osteotomy (arrowhead) performed of the trapezoid. This was done in conjunction with a CMC arthroplasty.
extensor pollicis brevis and performing a longitudinal capsulotomy. Care was taken to dissect the trapezium carefully from its anatomic position. Once it was removed in its entirety, the ST joint was examined. We scored marks at the one-third, one-half, and twothirds points of the overall height of the trapezoid after we measured these points with a micrometer. Sequential osteotomies were made transversely across the trapezoid, taking one-third and then onehalf and two-thirds of the trapezoid using a straight osteotome. After each resection, the wrist was placed in various positions: 20 RD and wrist neutral, 0 RD and 30 flexion, and 20 RD and 30 flexion, and then finally the wrist was taken through extremes of motion to see at what angle impingement occurred. In the second group, 4 cadavers were dissected. The same surgical approach was employed as in the first group. In these specimens, once the ST joint was reached, an oblique osteotomy was made. The radial side of the osteotomy began at the midpoint of the trapezoid and ended with about 1 mm of ST space on the ulnar side (Fig. 1). Each wrist was then taken through various positions to see at what angles impingement would occur. All measurements were recorded with a micrometer at the radial side of the osteotomy.
MATERIALS AND METHODS We obtained a sample of convenience of 9 cadaveric specimens sectioned at a level proximal to the elbow joint for this study and randomly assigned to 1 of 2 groups. The age of the cadavers ranged from 45 to 88 years (mean age, 66 years). No ST arthritis was noted on gross examination of the specimens. The lead author performed all dissections. In each cadaver, the contact points at the ST joint were observed with RD, WF, or both after resection of one-third of the trapezoid using a transverse cut. The wrists were placed manually in these positions and were measured with a goniometer. The space between the trapezoid and scaphoid increased with either wrist extension or ulnar deviation; therefore, these positions were not measured in the study. In the first group, 5 cadavers were dissected. A standard dorsal approach to the CMC joint was performed, retracting the abductor pollicis longus and J Hand Surg Am.
RESULTS In group 1, there was no contact between the scaphoid and trapezoid in neutral wrist position after any resection. In 1 of the 5 specimens, there was contact after the one-third resection in either isolated r
Vol. -, - 2019
TRAPEZOID EXCISION IN THUMB CMC ARTHROPLASTY
None of the two-thirds osteotomies had contact at any wrist position. They had a remaining space averaging 5.0 mm in neutral (range, 4.0e6.9 mm), 3.5 mm in 20 RD and 0 WF (range, 2.4e4.6 mm), 2.9 mm in 0 RD and 30 WF (range, 2.2e4.2 mm), and 2.5 mm in 20 RD and 30 WF (range, 1.7e3.7 mm) (Table 1). In addition, for group 1, we measured the angles of contact for each osteotomy. For the one-third osteotomies, this contact angle averaged 33 RD and 19 WF. In the one-half osteotomies, the first specimen had no contact even at 55 RD and 20 WF; however, the other 4 specimens had an average contact angle of 47 RD and 20 WF. The two-thirds osteotomies had no contact regardless of the wrist position, with an average space at 55 RD and 20 WF of 1.4 mm (range, 0.7e2.5 mm). In group 2, there was no contact in any specimen in any wrist position tested. There was a remaining space averaging 3.7 mm in neutral (range, 2.8e5.0 mm), 2.8 mm in 20 RD and 0 WF (range, 1.6e4.5 mm), 2.3 mm in 0 RD and 30 WF (range, 1.0e3.6 mm), and 1.8 mm in 20 RD and 30 WF (range, 1.0e3.2 mm). We tested the extreme wrist position of 20 RD and 55 WF; there was an average of 1.4 mm space remaining (range, 0.7e2.5 mm) (Table 2).
TABLE 1. Group 1 Results: Increasing Transverse Osteotomies. Raw Data From Each Cadaver in Transverse Osteotomy Group (Measurements in Millimeters of Space Remaining Between Scaphoid and Trapezoid) Extent of Transverse Osteotomy Wrist Position
1/3
1/2
2/3
2.9
5.3
6.9
20 RD, 0 Flex
1.9
2.0
4.4
0 RD, 30 Flex
2.1
2.8
3.3
1.4
1.5
3.0
Neutral
1.5
3.2
5.5
20 RD, 0 Flex
0.5
2.1
4.6
0 RD, 30 Flex
1.2
2.0
4.2
20 RD, 30 Flex
0.4
1.5
3.7
1.4
2.7
4.0
20 RD, 0 Flex
0.5
1.0
2.4
0 RD, 30 Flex
0.3
0.6
2.2
0.5
1.9
Cadaver #1 Neutral
20 RD, 30 Flex Cadaver #2
Cadaver #3 Neutral
20 RD, 30 Flex
Contact
Cadaver #4 Neutral
2.8
4.8
20 RD, 0 Flex
Contact
1.7
1.5
3.1
0 RD, 30 Flex
Contact
1.1
2.5
20 RD, 30 Flex
Contact
0.9
1.7
DISCUSSION Brown et al3 analyzed 69 cadaver thumbs radiographically and visually, noting both CMC and STT arthritis in 60% of specimens. However, radiographs and direct inspection of the STT joint at the time of surgery correlated with the radiographic findings in only 39% of cases. In the one-third osteotomies of group 1, there was an average space remaining of 1.9 mm in a neutral position, yet there was still contact at the ST joint in various wrist positions with 3 of 5 specimens. That amount of resection may be insufficient to prevent ST contact. We found that after a transverse osteotomy, the most likely position of contact at the ST joint is with RD and WF. However, when performing an oblique osteotomy, we noted no points of contact and there was an average of 1.8 mm of space remaining in 20 RD and 30 WF. In addition, there was no contact in any of the group 1 cadavers after resection of one-half the trapezoid. A potential point of concern is proximal migration of the index finger metacarpal after partial removal of the trapezoid. Wright et al6 examined the effects of partial or complete trapezoidectomy in conjunction with trapeziectomy in a cadaveric model. They showed that trapezium
Cadaver #5 Neutral
2.1
3.5
4.6
20 RD, 0 Flex
1.6
2.0
3.3
0 RD, 30 Flex 20 RD, 30 Flex
0.90
1.5
2.6
Contact
0.8
2.3
RD or flexion. In 3 of the 5 specimens, there was contact at one-third resection with 20 RD combined with 30 flexion. In osteotomies in which there was no contact, the remaining space averaged 1.9 mm in neutral (range, 1.4e2.9 mm), 1.1 mm in 20 RD and 0 WF (range, 0.5e1.9 mm), 1.1 mm in 0 RD and 30 WF (range, 0.3e2.1 mm), and 0.9 mm in 20 RD and 30 WF (range, 0.4e1.4 mm). None of the one-half osteotomies had contact at any wrist position. There was a remaining space averaging 3.5 mm in neutral (range, 2.7e5.3 mm), 1.7 mm in 20 RD and 0 WF (range, 1.0e2.1 mm), 1.6 mm in 0 RD and 30 WF (range, 0.6e2.8 mm), and 1.1 mm in 20 RD and 30 WF (range, 0.5e1.5 mm). J Hand Surg Am.
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TABLE 2.
TRAPEZOID EXCISION IN THUMB CMC ARTHROPLASTY
Average Space Remaining for Oblique Osteotomy Group (All Measurements in mm) Wrist Position
Space remaining (range)
Neutral
20 RD, 0 Flex
0 RD, 30 Flex
20 RD, 30 Flex
20 RD, 55 Flex
3.7 (2.8e5.0)
2.8 (1.6e4.5)
2.3 (1.0e3.6)
1.8 (1.0e3.2)
1.4 (0.7e2.5)
excision and partial trapezoidectomy had important effects on the biomechanics of the index metacarpal when loaded longitudinally. They also showed that even when 50% or more of the trapezoid was left, there was still 1 to 2 mm of proximal migration under load. We therefore disagree with the conclusion of Wright et al that a 50% transverse resection would be sufficient. In a neutral wrist position there was more than 3 mm of space, but in positions of WF or RD there is less than 2 mm of space, so proximal migration would put the trapezoid at risk for contact with the scaphoid. In our study, the one-third oblique osteotomy group had an average of 1.8 mm of space remaining, so this may be insufficient under conditions of axial load to prevent ST contact completely. There were limitations to this study. We did not perform tendon loading when performing our measurements; doing so might have changed our findings, likely decreasing the osteotomy space. We also had a limited number of specimens, and these did not have obvious signs of osteoarthritis at either the CMC or ST joints. When performing a transverse osteotomy of the trapezoid, one-half of the trapezoid or more should be resected to minimize contact in positions of RD or WF. If an oblique osteotomy is performed, only the
J Hand Surg Am.
radial half requires excision with a much smaller resection on the ulnar side. REFERENCES 1. 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. 2. Armstrong AL, Hunter JB, Davis TR. The prevalence of degenerative arthritis of the base of the thumb in postmenopausal women. J Hand Surg Br. 1994;19(3):340e341. 3. Brown GC, Roh MS, Strauch RJ, et al. Radiography and visual pathology of the osteoarthritic scaphotrapezio-trapezoidal joint, and its relationship to trapeziometacarpal osteoarthritis. J Hand Surg Am. 2003;28(5):739e743. 4. Barron OA, Catalano LW. Thumb basal joint arthritis. In: Wolfe SWW, Hotchkiss RN, Pederson WC, Kozin SH, eds. Green’s Operative Hand Surgery. 6th ed. Philadelphia, PA: Elsevier; 2011: 417. 5. Irwin AS, Maffulli N, Chesney RB. Scapho-trapezoid arthritis: a cause of residual pain after arthroplasty of the trapezio-metacarpal joint. J Hand Surg Br. 1995;20(3):346e352. 6. 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. 7. Wolf JM. Treatment of scaphotrapezio-trapezoid arthritis. Hand Clin. 2008;24(3):301e306. 8. Moritomo H, Viegas SF, Nakamura K, et al. The scaphotrapeziotrapezoidal joint. Part 1: an anatomic and radiographic study. J Hand Surg Am. 2000;25(5):899e910. 9. Bhatia A, Pisoh T, Touam C, et al. Incidence and distribution of scaphotrapeziotrapezoidal arthritis in 73 fresh cadaveric wrists. Ann Chir Main Memb Super. 1996;15(4):220e225.
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