SCIENTIFIC ARTICLE
Comparison of the Anatomical Dimensions and Mechanical Properties of the Dorsoradial and Anterior Oblique Ligaments of the Trapeziometacarpal Joint P. D’Agostino, MD, F. D. Kerkhof, MSc, M. Shahabpour, MD, J.-P. Moermans, MD, F. Stockmans, MD, E. E. Vereecke, PhD
Purpose The respective roles of the dorsoradial (DRL) and anterior oblique (AOL) ligaments in stability of the highly mobile trapeziometacarpal (TMC) joint remain disputed. Earlier publications have pointed to the AOL as the key stabilizing structure; yet, more recent publications have challenged the stabilizing role of the AOL, favoring the DRL as the main TMC joint stabilizer. We executed an anatomical study of the ligaments, including detailed dissection to quantify the length, width, and thickness of the AOL and DRL and tested the material properties of these ligaments. Methods Thirteen fresh frozen cadaveric thumbs from 9 specimens were used. Length, width, and thickness of the AOL and DRL were measured on magnetic resonance imaging and/or after dissection. Next, the first metacarpal and trapezium were isolated together with both ligaments, and both bones were cut sagittally to isolate a first metacarpaleAOLetrapezium and first metacarpaleDRLetrapezium complex from each thumb. These samples were subjected to cyclic loading in displacement-controlled tests. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample. Results Our results showed that the DRL is significantly shorter and thicker than the AOL, which is thin and ill-defined. Our results also indicate that the DRL has a higher stiffness than the AOL, making it a more likely candidate to provide joint stability. Conclusions Although the AOL has been asserted to be the primary restraint to dorsoradial subluxation, this view has been challenged over the past 10 years by several studies. These studies have shown the AOL to be relatively weak and compliant compared with the intermetacarpal and dorsoradial ligaments and have demonstrated that the DRL is the strongest and stiffest ligament of the TMC joint. Our studies confirm these findings. Clinical relevance This study indicates that the DRL is relatively stiff and thick, suggesting it should be repaired or reconstructed when disrupted to restore stability of the TMC joint.
From the Department of Development and Regeneration @ Kulak, Biomedical Sciences, KU Leuven; the Hand Clinic, Louise Medical Center; the Europe Clinic, St-Elisabeth Clinic; the Department of Radiology, UZ Brussel; the Centre de Chirurgie de la Main, Clinique du Parc Léopold; HUDERF, ULB, Brussels; and the Handgroep, AZ Groeninge, Kortrijk, Belgium. Received for publication July 23, 2013; accepted in revised form February 20, 2014.
to our disposal, and the anonymous reviewers for their valuable comments on the original manuscript. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
This study was partially funded via a research chair to E.E.V. and F.S. donated by the company Materialise (Materialise-Kulak Chair on Hand Surgery).
Corresponding author: Priscilla D’Agostino, MD, Department of Development and Regeneration @ Kulak, Biomedical Sciences Group, KU Leuven, Etienne Sabbelaan 53, B-8500 Kortrijk, Belgium; e-mail: [email protected].
The authors thank Stefan Goovaerts (KU Leuven) for his invaluable support in executing the material testing, the Biomechanics Section of the KU Leuven for putting their material tester
0363-5023/14/---0001$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2014.02.025
Ó 2014 ASSH
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
(J Hand Surg Am. 2014;-:-e-. Copyright Ó 2014 by the American Society for Surgery of the Hand. All rights reserved.) Key words Anterior oblique ligament, dorsoradial ligament, surgical approach, thumb base ligaments, trapeziometacarpal joint.
T
(TMC) joint is complex with high intrinsic mobility and limited intrinsic stability, offering a wide range of motion to the thumb.1 The particular configuration of the articular facets of the joint, to date described as a saddle joint with 2 axes of stable movement, is responsible for the wide range of motion.2,3 The high intrinsic mobility and the intensive use of the thumb in daily activities has been linked to the high prevalence osteoarthritis of the TMC joint.4e6 In addition, this joint is also a frequent site of fracture, especially Bennett and Rolando fractures of the first metacarpal base (MC1). Epidemiologically, the MC1 fracture is the second most frequent hand fracture in adults.7 Both TMC joint pathologies, osteoarthritis and MC1 fractures, often require surgical treatment with exposure of the TMC joint via an anterior (ie, elevating the thenar muscles) or a posterior approach (access between the abductor pollicis longus and the extensor pollicis brevis tendons). Although the ligamentous TABLE 1. Ligaments AOL
DRL
anatomy is not always on a surgeon’s mind, the surgical plan is often indirectly guided by ligamentous anatomy. For example, ligamentoplasty after trapeziectomy using a flexor carpi radialis slip was originally proposed with the functional importance of the anterior oblique ligament (AOL) as prime stabilizer in mind,8 dorsal capsulorrhaphy after total joint replacement is believed to improve joint stability,9 and probably the clearest example is the ligamentoplasty proposed by Eaton and Littler2 for TMC joint instability, which was intended to reconstruct the AOL2 but which has been challenged to also reconstruct the dorsoradial ligament (DRL).10,11 Classically, the choice of 1 surgical approach over the other is based on the surgeon’s education and experience and on some early descriptions of the TMC joint-stabilizing structures.2 The anatomical structures transsected vary according to the surgical approach (anterior vs posterior), and this may have an important impact on the functional outcome of the procedure.
HE TRAPEZIOMETACARPAL
AOL and DRL Nomenclature Anatomical Nomenclature
Studies
TMC ligament
von Lanz and Wachsmuth, 195932
Palmar ligament (superficial) Ulnar ligament (deep)
Spinner, 196533 Weitbrecht and Kaplan, 196934
Anterior ligament
Eaton and Littler, 196935
Lunate ligament
Rouvière and Delmas, 197036
Ulnar ligament
Pieron, 197337 Imaeda et al, 199338
Palmar oblique ligament
Bojsen-Møller, 197639
Palmar beak ligament
Pellegrini et al, 199328
Superficial AOL Deep AOL
Pellegrini, 199127 Bettinger et al, 199912
Retinaculometacarpal ligament
Kuhlmann, 20013
Radial ligament of CMC joint
Haines, 194440
Lateral ligament
Spinner, 196533
Dorsal ligament
Weitbrecht and Kaplan, 196934
Laterodorsal ligament
Pieron, 197337
Lateral ligament of CMC joint
Napier, 198041
APL expansion
Pellegrini et al, 199328
Dorsoradial ligament
Bettinger et al, 199912
DRL þ dorsal central ligament
Ladd et al, 201216
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
TABLE 2.
Sample Composition
Individuals
Sample
Age (y)
Sex
AOL
DRL
Eaton Stage
1
622
85
M
R
R
II
2
624
78
F
R, L
R, L
I
3
628
52
M
R, L
R, L
I
4
632
58
M
R
R
I
5
633*
66
F
R, L
R, L
II
6
635
78
M
L
L
I
7
636
86
F
L
L
II
8
639
72
M
L
L
I
9
655*
88
F
R, L
R, L
II
n ¼ 13
n ¼13
n¼9 *Samples for which no MRI data were available.
Anatomical studies do not agree on the identification, nomenclature, and role of the ligaments (Table 1). Up to 16 different ligaments have been described,12 of which the DRL and the deep portion of the AOL are regarded as main stabilizers of the TMC joint.10e18 Our study focused on the differences in anatomy and material properties between the DRL and the AOL. Our study aimed to provide qualitative and quantitative anatomical data of the DRL and AOL that could be used to identify and preserve or reconstruct the strongest stabilizing structures and help in choosing the best surgical approach. The anatomical and mechanical data presented in this study could also contribute to establish new concepts of TMC joint surgical reconstructive procedures.
FIGURE 1: Coronal T2-weighted MRI of a cadaver specimen injected with contrast agent and with indication of the DRL (thick arrow) and AOL (thin arrow).
MATERIALS AND METHODS Specimens Thirteen fresh frozen hands from 9 human specimens with an average age of 74 years were used for this study. The sample included both males and females and both left and right hands (unilateral and bilateral sampling) (Table 2). The specimens were segmented above the elbow and were kept frozen at -18 C until they were dissected. Standard x-rays and visual inspection of the joint surfaces were used to ascertain the absence of musculoskeletal pathologies. Specimens with Eaton stage III and IV (radiographic classification as defined by Van Heest and Kallemeier19) were excluded from the study.
the thawed cadaveric hands. MRIs were done on a set of 9 hands because we had limited access to MRI, so MRI could not be obtained for all 13 specimens. The TMC joint was injected with a gadolinium contrast agent by a hand surgeon (P.D.A.) using fluoroscopic control.20,21 Then, specimens underwent MRI following an a priori defined protocol of acquisition sequences in coronal, sagittal, and oblique planes. The resolution of the sequences was as follows: pd spair vista, T2W-TSE and PDW-TSE (2-mm slices); voxel size: 0.284 mm, 3D DESS (0.45-mm slices); voxel size: 0.253 mm. These acquisition sequences were chosen because they provided the best combination of image contrast and spatial resolution allowing good visualization and accurate 2-dimensional measurement of the ligaments (Fig. 1). Length and thickness of the ligaments were obtained on selected calibrated MRI images in different planes using dedicated image processing software
MRI acquisition and analysis Prior to dissection, magnetic resonance images (MRI) (3T Achieva, Philips Medical Systems, Universitair Ziekenhuis Brussel, Brussels, Belgium) were taken of J Hand Surg Am.
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
FIGURE 2: A Harvesting en bloc of the MC1 and trapezium (Trap). B The DRL is delineated in green adjacent to the posterior oblique ligament (POL). During our dissections, the DRL appeared like a continuous sheet at the dorsoradial side of the joint; we did not observe a DCL as a distinct ligament. C The AOL is indicated in blue.
(ImageJ 1.45s, W. Rasband, National Institutes of Health, Washington, DC). Lengths were measured between the deep osseous attachments of the ligaments. Several measurements were obtained on each sequence, and the arithmetic mean of all measurements per ligament was calculated.
for each specimen. This resulted in 26 separate boneligament-bone complexes used to evaluate the material properties of the 2 ligaments (13 AOL and 13 DRL) (Fig. 3). These samples were mounted in a material testing rig (LM1-TestBench, Bose Corp., Eden Prairie, MN), and cyclic, displacement-controlled tests (2 Hz; 40 cycles; preconditioning at 0.5 N) were executed on each sample until a maximal loading of 150 N (7/26), until ligament rupture (12/26), bone rupture (5/26), or simultaneous ligament and bone rupture (2/26)15,23 (Fig. 4). Throughout the experiment, the sample was kept moist with saline. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample. The stiffness was calculated as the slope of the linear part of the force-displacement curve in cycle 20 to account for conditioning of the ligament in the first cycles. The highest recorded stiffness obtained in the different subsequent tests was reported for each ligament. The hysteresis was calculated as the difference between the ascending and the descending curves (expressed in percentages). Stiffness was calculated to assess the stabilizing role of both ligaments, whereas hysteresis indicated the energy loss during loading.
Dissection technique and measurements Before dissection, the hands were thawed at room temperature. Exposure of the TMC joint was achieved through a combined dorsal and volar approach, reflecting all anatomical structures until reaching the deep ligament layer. The dissection was performed under 4.5 loupe magnification by a fully trained hand surgeon (P.D.A.). The origin, insertion, and fiber orientation of both the DRL and the AOL were identified based on anatomical descriptions of Berger.22 Length and width of the ligaments were measured in a position of in situ maximal passive tension as described by Bettinger et al12 with a digital caliper (CDCP30PMX, Mitutoya, Kawasaki, Japan; 0.01 mm). Sample preparation and material testing The MC1 and trapezium were harvested en bloc with both ligaments attached in each cadaver hand (Fig. 2). All ligaments except for the DRL and AOL were removed before material testing. An ultrasonic bone saw was used to sagittally cut the bones in a MC1AOL-trapezium and MC1-DRL-trapezium complex J Hand Surg Am.
Statistical analysis All data are reported as mean SD for the DRL and AOL, respectively. Pairwise Wilcoxon signed rank r
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FIGURE 3: A Preparation of the samples prior to mounting in the material tester. Shown are B MC1-AOL-Trap (blue) and MC1-DRLTrap (green) complexes and C a close view of the articular surfaces of the TMC joint.
FIGURE 4: A Bone blocks are filled with epoxy to provide extra strength to the bone. B Asterisk shows the ligament rupture.
tests were used to compare the length measurements obtained via MRI and via dissection and to compare the dimensions and material properties between both ligaments. Wilcoxon tests were chosen because not all obtained measurements displayed a clearly normal distribution. Significance was set at P of .05.
originates from the dorsoradial tubercle of the trapezium and inserts onto the dorsal edge of the base of MC1 (Fig. 5). The length of the DRL obtained via MRI amounted on average to 10.0 mm (SD ¼ 1.1 mm) versus 12.9 mm (SD ¼ 2.1 mm) obtained during dissection. The average thickness of the DRL was 1.1 mm (SD ¼ 0.2 mm) and the average width was 12.1 mm (SD ¼ 1.6 mm) (Tables 3, 4 and 5). The AOL is located just beneath the thenar muscles and is intimately linked to them. The AOL originates from the volar tubercle of the trapezium and inserts across the volar ulnar tubercle (palmar beak) of the first metacarpal (Fig. 6). In our dissections, we consistently found a single layer with a thin and fragile structure. The length of the AOL measured via MRI gave an average length of 12.2 mm (SD ¼ 2.1 mm), and the length obtained during dissection amounted on
RESULTS Anatomical description and dimensions of the ligaments Both ligaments were identified in all 13 unfixed hands using the principles of Berger.22 The DRL is covered on its dorsoradial side by the abductor pollicis longus, which attaches distally on the lateral side of the first metacarpal and is located just radially to the posterior oblique ligament, which is immediately adjacent to the DRL. The DRL J Hand Surg Am.
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FIGURE 5: Macroscopic anatomy of the DRL as observed during detailed dissection, in flexion A and extension B of the thumb.
TABLE 3.
Length Measurements Obtained via MRI and Dissection for DRL and AOL DRL
AOL
MRI Length (mm)
Dissection Length (mm)
MRI Length (mm)
Dissection Length (mm)
622R
10.0
17.4
14.0
18.8
624R
10.0
13.3
14.3
13.5
624L
9.0
12.5
14.1
15.0
628R
11.6
13.1
13.2
13.5
628L
11.5
12.1
12.4
13.9
632R
10.3
12.4
10.7
12.8
635L
8.5
11.4
12.2
10.9
636L
9.2
14.5
10.8
11.1
639L
9.7
13.5
7.7
12.1
Mean
10.0
12.9
12.2
13.0
1.0
2.1
2.1
2.6
Sample
SD %RSD
11
17
18
20
%RSD ¼ relative SD (percentage).
average to 13.0 mm (SD ¼ 2.6 mm). The average thickness of the AOL was 0.6 mm (SD ¼ 0.1 mm), and average width was 13. 6 mm (SD ¼ 2.6 mm) (Tables 3, 4, and 5). Statistical analysis of the anatomical data demonstrated a significant difference between the length of the DRL obtained via MRI and during dissection (W ¼ 0; P < .005). The methods did not result in a significantly different length measurement for the AOL (W ¼ 37; P ¼ .1). The MRI method was considered to give the most accurate and reproducible measurement of ligament length and thickness because MRI allows exact and precise visualization of the footprint of the ligament on bone and was, therefore, used in further analysis. Comparison of the MRI dimensions of the DRL and the AOL indicated that the DRL was significantly shorter, thicker, and narrower than the AOL.
DRL was 89 N/mm (SD ¼ 21 N/mm) and of the AOL was 65 N/mm (SD ¼ 30 N/mm). The hysteresis of the DRL amounted on average to 25% (SD ¼ 3%) and 21% (SD ¼ 4%) for the AOL (Tables 4 and 5). Statistical analysis of the data demonstrated the DRL to be significantly stiffer than the AOL (W ¼ 78; P < .05), with a significantly higher hysteresis (W ¼ 66; P < .05) (Tables 4 and 5). DISCUSSION Functional significance of the volar and dorsal ligaments To date, strong importance has been given to the AOL in providing TMC joint stability and in restraining dorsoradial subluxation. Our findings suggest, however, that at least equal importance should be given to the stiffer and thicker DRL, a finding that is also supported by recent biomechanical studies. The longstanding importance given to the AOL is upheld by the success of surgical procedures that include AOL reconstruction.8,24e26 In 1973, Eaton and Littler2 described the dorsal ligament as a thin and poorly defined structure and posited that it contributed
Material properties of the ligaments Force-elongation curves of each DRL and AOL sample are represented in Figure 7. The average stiffness of the J Hand Surg Am.
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
TABLE 4.
Dimensions and Material Properties of the DRL
Specimens
Length* (mm)
Thickness* (mm)
Width (mm)
S (MPa)
H (%)
624R
10.0
1.2
10.9
79
27
624L
9.0
1.3
11.9
76
622R
10.0
1.2
14.4
97
24
628L
11.5
1.2
11.3
107
21
635L
8.5
1.1
11.9
96
23
639L
9.7
0.8
11.3
52
32
636L
9.2
0.9
11.4
87
25
632R
10.3
1.1
10.2
73
22
628R
11.6
1.2
10.7
140
24
633L
12.3
91
26
633R
15.8
100
24
655L
11.3
78
26
655R n
11.5
81
23
9
13
13
13
10.0
1.1
12.1
89
25
1.0
0.2
1.6
21
3
9
Mean SD H, hysteresis; S, stiffness. *MRI measurements.
TABLE 5.
Dimensions and Material Properties of the AOL
Specimens
Length* (mm)
Thickness* (mm)
Width (mm)
S (MPa)
H (%)
624R
14.3
0.7
14.3
60
19
624L
14.1
0.9
12.6
23
24
622R
14.0
0.7
20.5
79
22
628L
12.4
0.6
13.8
58
25
635L
12.2
0.6
10.2
25
22
639L
7.7
0.4
12.8
109
13
636L
10.8
0.6
13.6
65
22
632R
10.7
0.7
12.7
68
15
628R
13.2
0.6
13.5
105
25
633L
12.3
81
19
633R
15.2
102
24
655L
11.9
33
23
655R
13.4
38
23
n Mean SD
9
13
13
13
12.2
9
0.6
13.6
65
21
2.1
0.1
2.6
30
4
H, hysteresis; S, stiffness. *MRI measurements.
little to the stability of the joint. The AOL, however, was considered as the key structure in maintaining thumb stability. In 1991, Pellegrini27 suggested a direct correlation between the condition of the articular J Hand Surg Am.
surfaces of the TMC joint and the integrity of the AOL, supporting the importance of the AOL in articular wear. Pellegrini et al28 also demonstrated that detachment or laxity of the AOL leads to dorsal r
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
FIGURE 6: Macroscopic anatomy of the AOL as observed during detailed dissection, in flexion A and extension B of the thumb.
FIGURE 7: Force-elongation curves of A the DRL and B AOL samples. Each loop represents a different sample.
translation of MC1 on the trapezium in lateral pinch. Imaeda et al29 suggested that TMC joint stability is provided by the AOL combined with secondary support from the intermetacarpal and ulnar collateral ligaments. Based on these findings, de la Caffinière30 recommended a posterior approach of the TMC joint in total joint arthroplasty to preserve the anterior ligaments and their stabilizing function. The importance of the anterior ligaments has, however, been challenged by several studies. Strauch and colleagues13 pointed to the DRL as the primary restraint to dorsoradial subluxation in traumatic dislocations of the TMC joint. In a biomechanical study, Van Brenk et al14 confirmed the role of the DRL as the most important ligament in preventing dorsoradial subluxation and advocated preserving or reconstructing it in TMC joint surgery. Bettinger et al12 recognized that the AOL is thin, weak, and translucent whereas the DRL is the shortest, broadest, and thickest TMC joint ligament. More recently, Nanno and colleagues10 confirmed that the DRL was the thickest ligament attached to the trapezium and suggested that the DRL should contribute substantially to TMC joint stability. However, the importance of a ligament cannot accurately be inferred solely from dimensions and position, because its stabilizing potential is largely determined by its material properties. In 2000, Bettinger et al15 determined the relative stiffness and strength of all ligaments surrounding the J Hand Surg Am.
TMC joint. The DRL was the strongest and stiffest ligament stabilizing the TMC joint, whereas the AOL was relatively weak and compliant and, therefore, identified as a poor stabilizer of the TMC joint. In 2007, Colman et al11 generated conflicting data with the earlier work of Pellegrini in a biomechanical cadaver study.1,28 After random transsection of the AOL or DRL, the DRL proved to be more important than the AOL in providing stability and preventing dorsoradial translation of the base of MC1. Finally, 2 recent studies of the TMC joint ligaments conducted by Ladd and colleagues16,17 also challenged the primary importance of the AOL. They consistently identified the AOL as a thin, capsular tissueelike structure with low cellularity, inferring it would be a poor stabilizer of the TMC joint. These studies10,11,14e16 confirmed earlier suggestions of Strauch and colleagues14,18 that the DRL, and not the volar ligaments, is the primary restraint to dorsal translation of the TMC joint, a finding supported by the higher stiffness of the DRL compared with the AOL as demonstrated in our study and by Bettinger et al.15 Whereas Bettinger et al12,15 provided a comprehensive overview of the ligaments surrounding the TMC joint, our study specifically focused on the differences between the DRL and the AOL, in terms of both anatomy and material properties, in order to infer which ligament should be preserved and/ or reconstructed to achieve joint stability. Furthermore, r
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we did not find clear evidence that the AOL is present as 2 distinct structures (superficial and deep) as described in previous studies.12,27 Macroscopically, we found the AOL to be a poorly defined, diaphanous, and capsular-like structure.
REFERENCES 1. Pellegrini VD Jr. Pathomechanics of the thumb trapeziometacarpal joint. Hand Clin. 2001;17(2):175e184, viieviii. 2. Eaton RG, Littler JW. Ligament reconstruction for painful thumb carpometacarpal joint. J Bone Joint Surg Am. 1973;55(8):1655e1666. 3. Kuhlmann JN. Importance of the posteromedial trapeziometacarpal ligamentous complex. Chir Main. 2001;20(1):31e47. 4. Armstrong AL, Hunter JB, Davis TR. The prevalence of degenerative arthritis of the base of the thumb in postmenopausal woman. J Hand Surg Br. 1994;19(3):340e341. 5. Winzeler S, Rosenstein BD. Occupational injury and illness of the thumb. Causes and solutions. AAOHN J. 1996;44(10):487e492. 6. Haara M, Heliovaara M, Kroger H, et al. Osteoarthritis in the carpometacarpal joint of the thumb. Prevalence and associations with disability and mortality. J Bone Joint Surg Am. 2004;86(7): 1452e1457. 7. Court-Brown CM, Caesar B. Epidemiology of adult fractures: a review. Injury. 2006;37(8):691e697. 8. Burton RI, Pellegrini VD Jr. Surgical management of basal joint arthritis of the thumb. Part II. Ligament reconstruction with tendon interposition arthroplasty. J Hand Surg Am. 1986;11(3):324e332. 9. Teissier J. Lateral approach: the royal way for the trapezo-metacarpal prosthesis. Chir Main. 2011;30:S95eS97. 10. Nanno M, Buford WL Jr, Patterson RM, Andersen CR, Viegas SF. Three-dimensional analysis of the ligamentous attachments of the first carpometacarpal joint. J Hand Surg Am. 2006;31(7):1160e1170. 11. Colman M, Mass DP, Draganich LF. Effects of the deep anterior oblique and dorsoradial ligaments on trapeziometacarpal joint stability. J Hand Surg Am. 2007;32(3):310e317. 12. Bettinger PC, Linscheid RL, Berger RA, Cooney WP, An K-N. An anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal joint. J Hand Surg Am. 1999;24(4):786e798. 13. Strauch RJ, Behrman MJ, Rosenwasser MP. Acute dislocation of the carpometacarpal joint of the thumb: An anatomic and cadaver study. J Hand Surg Am. 1994;19(1):93e98. 14. Van Brenk B, Richards RR, Mackay MB, Boynton EL. A biomechanical assessment of ligaments preventing dorsoradial subluxation of the trapeziometacarpal joint. J Hand Surg Am. 1998;23(4):607e611. 15. Bettinger P, Smutz W, Linscheid R, Cooney W, An K-N. Material properties of the trapezial and trapeziometacarpal ligaments. J Hand Surg Am. 2000;25(6):1085e1095. 16. Ladd AL, Lee J, Hagert E. Macroscopic and microscopic analysis of the thumb carpometacarpal ligaments. A cadaveric study of ligament anatomy and histology. J Bone Joint Surg Am. 2012;94(16):1468e1477. 17. Zhang AY, Van Nortwick S, Hagert E, Ladd AL. Thumb carpometacarpal ligaments inside and out: a comparative study of arthroscopic and gross anatomy from the Robert A. Chase Hand and Upper Limb Center at Stanford University. J Wrist Surg. 2013;2(1):55e62. 18. Strauch RJ, Rosenwasser MP, Behrman MJ. A biomechanical assessment of ligaments preventing dorsoradial subluxation of the trapeziometacarpal joint. J Hand Surg Am. 1999;24(1):198e199. 19. Van Heest AE, Kallemeier P. Thumb carpal metacarpal arthritis. J Am Acad Orthop Surg. 2008;16(3):140e151. 20. Cardoso FN, Kim HJ, Albertotti F, Botte MJ, Resnick D, Chung CB. Imaging the ligaments of the trapeziometacarpal joint: MRI compared with MR arthrography in cadaveric specimens. AJR Am J Roentgenol. 2009;192(1):W13eW19. 21. Pike J, Koulouris G, van Wettering N, Hoy G. MR imaging of thumb carpometacarpal joint ligament injuries. J Hand Surg Br. 2004;29(1): 46e54. 22. Berger RA. The anatomy of the ligaments of the wrist and distal radioulnar joints. Clin Orthop Relat Res. 2001;383:32e40. 23. Vereecke EE, Channon AJ. The role of hind limb tendons in gibbon locomotion: springs or strings? J Exp Biol. 2013;216(Pt 21):3971e3980. 24. Eaton RG, Lane LB, Littler JW, Keyser JJ. Ligament reconstruction for the painful thumb carpometacarpal joint: A long-term assessment. J Hand Surg Am. 1984;9(5):692e699.
Limitations of the study There are some critical considerations to be made linked to the sample composition and experimental procedure of this study. The mean age of our specimens was relatively high (74 y) and may have had an impact on ligament integrity, but it is comparable with those of other studies.12,27 Subjects with advanced stages of osteoarthritis were excluded to ensure sampling of normal ligamentous structures, representative for normal TMC anatomy (Table 2). Two different methods were used to measure length and thickness of the ligaments. Statistical analysis of our results indicated a significant difference between length measurements obtained via MRI and those obtained with a caliper. MRI was selected as the most accurate method because we noted difficulties in identifying the exact location of the ligament insertions during dissection, whereas precise identification of these ligaments insertions was possible on high resolution MRI. In addition, MRI allowed in situ measurement of the ligament dimensions in a resting thumb position. CLINICAL RELEVANCE Stability of the TMC joint relies on muscles, tendons, and ligaments crossing the joint. Laxity of the ligaments has been proposed as a mechanism for the development of osteoarthritis of the TMC joint.31 Understanding ligament function is thus of primordial importance in optimizing surgical interventions. Preservation or reconstruction of all ligaments is not always possible during surgery. A choice has then to be made to sacrifice or reconstruct certain ligaments or ligament functions. Our results point to significant differences in dimensions and material properties between the AOL and the DRL and support the findings of the most recent studies that underline the functional importance of the thick DRL.10,11,14e16,18 Our findings suggest that Eaton and Littler’s concept, relying on the volar ligament,10 should be reconsidered and that the importance of the DRL should be taken into account when planning surgeries with an extensive (ie, noneligament sparing) approach or ligament reconstruction of the TMC joint. J Hand Surg Am.
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25. 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. 26. Thompson JS. Surgical treatment of trapeziometacarpal arthrosis. Adv Orthop Surg. 1986;10:105. 27. Pellegrini VD Jr. Osteoarthritis of the trapeziometacarpal joint: the pathophysiology of articular cartilage degeneration. I. Anatomy of the aging joint. J Hand Surg Am. 1991;16(6):967e974. 28. Pellegrini VD Jr, Olcott CW, Hollenberg G. Contact patterns in the trapeziometacarpal joint: the role of the palmar beak ligament. J Hand Surg Am. 1993;18(2):238e244. 29. Imaeda T, An KN, Cooney W III. Functional anatomy and biomechanics of the thumb. Hand Clin. 1992;8(1):9e15. 30. de la Caffinière JY. Longevity factors in total trapezometacarpal prosthèses. Chir Main. 2001;20(1):63e67. 31. Jonsson H, Valtysdottir S, Kjartansson O, Brekkan A. Hypermobility associated with osteoarthritis of the thumb base: a clinical and radiological subset of hand osteoathritis. Ann Rheum Dis. 1996;55(8):540e543. 32. von Lanz TR, Wachsmuth W. Das sattelgelenk des daumes, articulatio carpo-metacarpes pollicis. In: Praktische anatomie: ein lehrund
J Hand Surg Am.
33. 34. 35. 36. 37.
38. 39. 40. 41.
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hilfsbuch der anatomischen grundlagen ärztlichen Handelns. Berlin: Springer-Verlag; 1959:261. Spinner M, ed. Kaplan’s Functional and Surgical Anatomy of the Hand. 2nd ed. Philadelphia: JB Lippincott; 1965:121e124. Weitbrecht J, Kaplan EB. Syndesmology. Philadelphia: WB Saunders; 1969. Eaton RG, Littler JW. A study of the basal joint of the thumb. Treatment of its disabilities by fusion. J Bone Joint Surg Am. 1969;51(4):661e668. Rouvière H, Delmas A. Anatomie Humaine. Descriptive, topographique et fonctionnelle. Paris: Elsevier-Masson; 1970. Pieron A. The mechanism of the first carpometacarpal (CMC) joint. An anatomical and mechanical analysis. Acta Orthop Scand. 1973;148: 1e104. Imaeda T, An K-N, Cooney WP III, Linscheid R. Anatomy of trapeziometacarpal ligaments. J Hand Surg Am. 1993;18(2):226e231. Bojsen-Møller F. Osteoligamentous guidance of the movements of the human thumb. Am J Anat. 1976;147(1):71e80. Haines RW. The mechanism of rotation of the first carpo-metacarpal joint. J Anat. 1944;78(Pt 1e2):44e46. Napier J. Hands. New York: Pantheon; 1980:71.
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Comparison of the Anatomical Dimensions and Mechanical Properties of the Dorsoradial and Anterior Oblique Ligaments of the Trapeziometacarpal Joint P. D’Agostino, MD, F. D. Kerkhof, MSc, M. Shahabpour, MD, J.-P. Moermans, MD, F. Stockmans, MD, E. E. Vereecke, PhD
Purpose The respective roles of the dorsoradial (DRL) and anterior oblique (AOL) ligaments in stability of the highly mobile trapeziometacarpal (TMC) joint remain disputed. Earlier publications have pointed to the AOL as the key stabilizing structure; yet, more recent publications have challenged the stabilizing role of the AOL, favoring the DRL as the main TMC joint stabilizer. We executed an anatomical study of the ligaments, including detailed dissection to quantify the length, width, and thickness of the AOL and DRL and tested the material properties of these ligaments. Methods Thirteen fresh frozen cadaveric thumbs from 9 specimens were used. Length, width, and thickness of the AOL and DRL were measured on magnetic resonance imaging and/or after dissection. Next, the first metacarpal and trapezium were isolated together with both ligaments, and both bones were cut sagittally to isolate a first metacarpaleAOLetrapezium and first metacarpaleDRLetrapezium complex from each thumb. These samples were subjected to cyclic loading in displacement-controlled tests. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample. Results Our results showed that the DRL is significantly shorter and thicker than the AOL, which is thin and ill-defined. Our results also indicate that the DRL has a higher stiffness than the AOL, making it a more likely candidate to provide joint stability. Conclusions Although the AOL has been asserted to be the primary restraint to dorsoradial subluxation, this view has been challenged over the past 10 years by several studies. These studies have shown the AOL to be relatively weak and compliant compared with the intermetacarpal and dorsoradial ligaments and have demonstrated that the DRL is the strongest and stiffest ligament of the TMC joint. Our studies confirm these findings. Clinical relevance This study indicates that the DRL is relatively stiff and thick, suggesting it should be repaired or reconstructed when disrupted to restore stability of the TMC joint.
From the Department of Development and Regeneration @ Kulak, Biomedical Sciences, KU Leuven; the Hand Clinic, Louise Medical Center; the Europe Clinic, St-Elisabeth Clinic; the Department of Radiology, UZ Brussel; the Centre de Chirurgie de la Main, Clinique du Parc Léopold; HUDERF, ULB, Brussels; and the Handgroep, AZ Groeninge, Kortrijk, Belgium. Received for publication July 23, 2013; accepted in revised form February 20, 2014.
to our disposal, and the anonymous reviewers for their valuable comments on the original manuscript. No benefits in any form have been received or will be received related directly or indirectly to the subject of this article.
This study was partially funded via a research chair to E.E.V. and F.S. donated by the company Materialise (Materialise-Kulak Chair on Hand Surgery).
Corresponding author: Priscilla D’Agostino, MD, Department of Development and Regeneration @ Kulak, Biomedical Sciences Group, KU Leuven, Etienne Sabbelaan 53, B-8500 Kortrijk, Belgium; e-mail: [email protected].
The authors thank Stefan Goovaerts (KU Leuven) for his invaluable support in executing the material testing, the Biomechanics Section of the KU Leuven for putting their material tester
0363-5023/14/---0001$36.00/0 http://dx.doi.org/10.1016/j.jhsa.2014.02.025
Ó 2014 ASSH
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Published by Elsevier, Inc. All rights reserved.
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
(J Hand Surg Am. 2014;-:-e-. Copyright Ó 2014 by the American Society for Surgery of the Hand. All rights reserved.) Key words Anterior oblique ligament, dorsoradial ligament, surgical approach, thumb base ligaments, trapeziometacarpal joint.
T
(TMC) joint is complex with high intrinsic mobility and limited intrinsic stability, offering a wide range of motion to the thumb.1 The particular configuration of the articular facets of the joint, to date described as a saddle joint with 2 axes of stable movement, is responsible for the wide range of motion.2,3 The high intrinsic mobility and the intensive use of the thumb in daily activities has been linked to the high prevalence osteoarthritis of the TMC joint.4e6 In addition, this joint is also a frequent site of fracture, especially Bennett and Rolando fractures of the first metacarpal base (MC1). Epidemiologically, the MC1 fracture is the second most frequent hand fracture in adults.7 Both TMC joint pathologies, osteoarthritis and MC1 fractures, often require surgical treatment with exposure of the TMC joint via an anterior (ie, elevating the thenar muscles) or a posterior approach (access between the abductor pollicis longus and the extensor pollicis brevis tendons). Although the ligamentous TABLE 1. Ligaments AOL
DRL
anatomy is not always on a surgeon’s mind, the surgical plan is often indirectly guided by ligamentous anatomy. For example, ligamentoplasty after trapeziectomy using a flexor carpi radialis slip was originally proposed with the functional importance of the anterior oblique ligament (AOL) as prime stabilizer in mind,8 dorsal capsulorrhaphy after total joint replacement is believed to improve joint stability,9 and probably the clearest example is the ligamentoplasty proposed by Eaton and Littler2 for TMC joint instability, which was intended to reconstruct the AOL2 but which has been challenged to also reconstruct the dorsoradial ligament (DRL).10,11 Classically, the choice of 1 surgical approach over the other is based on the surgeon’s education and experience and on some early descriptions of the TMC joint-stabilizing structures.2 The anatomical structures transsected vary according to the surgical approach (anterior vs posterior), and this may have an important impact on the functional outcome of the procedure.
HE TRAPEZIOMETACARPAL
AOL and DRL Nomenclature Anatomical Nomenclature
Studies
TMC ligament
von Lanz and Wachsmuth, 195932
Palmar ligament (superficial) Ulnar ligament (deep)
Spinner, 196533 Weitbrecht and Kaplan, 196934
Anterior ligament
Eaton and Littler, 196935
Lunate ligament
Rouvière and Delmas, 197036
Ulnar ligament
Pieron, 197337 Imaeda et al, 199338
Palmar oblique ligament
Bojsen-Møller, 197639
Palmar beak ligament
Pellegrini et al, 199328
Superficial AOL Deep AOL
Pellegrini, 199127 Bettinger et al, 199912
Retinaculometacarpal ligament
Kuhlmann, 20013
Radial ligament of CMC joint
Haines, 194440
Lateral ligament
Spinner, 196533
Dorsal ligament
Weitbrecht and Kaplan, 196934
Laterodorsal ligament
Pieron, 197337
Lateral ligament of CMC joint
Napier, 198041
APL expansion
Pellegrini et al, 199328
Dorsoradial ligament
Bettinger et al, 199912
DRL þ dorsal central ligament
Ladd et al, 201216
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
TABLE 2.
Sample Composition
Individuals
Sample
Age (y)
Sex
AOL
DRL
Eaton Stage
1
622
85
M
R
R
II
2
624
78
F
R, L
R, L
I
3
628
52
M
R, L
R, L
I
4
632
58
M
R
R
I
5
633*
66
F
R, L
R, L
II
6
635
78
M
L
L
I
7
636
86
F
L
L
II
8
639
72
M
L
L
I
9
655*
88
F
R, L
R, L
II
n ¼ 13
n ¼13
n¼9 *Samples for which no MRI data were available.
Anatomical studies do not agree on the identification, nomenclature, and role of the ligaments (Table 1). Up to 16 different ligaments have been described,12 of which the DRL and the deep portion of the AOL are regarded as main stabilizers of the TMC joint.10e18 Our study focused on the differences in anatomy and material properties between the DRL and the AOL. Our study aimed to provide qualitative and quantitative anatomical data of the DRL and AOL that could be used to identify and preserve or reconstruct the strongest stabilizing structures and help in choosing the best surgical approach. The anatomical and mechanical data presented in this study could also contribute to establish new concepts of TMC joint surgical reconstructive procedures.
FIGURE 1: Coronal T2-weighted MRI of a cadaver specimen injected with contrast agent and with indication of the DRL (thick arrow) and AOL (thin arrow).
MATERIALS AND METHODS Specimens Thirteen fresh frozen hands from 9 human specimens with an average age of 74 years were used for this study. The sample included both males and females and both left and right hands (unilateral and bilateral sampling) (Table 2). The specimens were segmented above the elbow and were kept frozen at -18 C until they were dissected. Standard x-rays and visual inspection of the joint surfaces were used to ascertain the absence of musculoskeletal pathologies. Specimens with Eaton stage III and IV (radiographic classification as defined by Van Heest and Kallemeier19) were excluded from the study.
the thawed cadaveric hands. MRIs were done on a set of 9 hands because we had limited access to MRI, so MRI could not be obtained for all 13 specimens. The TMC joint was injected with a gadolinium contrast agent by a hand surgeon (P.D.A.) using fluoroscopic control.20,21 Then, specimens underwent MRI following an a priori defined protocol of acquisition sequences in coronal, sagittal, and oblique planes. The resolution of the sequences was as follows: pd spair vista, T2W-TSE and PDW-TSE (2-mm slices); voxel size: 0.284 mm, 3D DESS (0.45-mm slices); voxel size: 0.253 mm. These acquisition sequences were chosen because they provided the best combination of image contrast and spatial resolution allowing good visualization and accurate 2-dimensional measurement of the ligaments (Fig. 1). Length and thickness of the ligaments were obtained on selected calibrated MRI images in different planes using dedicated image processing software
MRI acquisition and analysis Prior to dissection, magnetic resonance images (MRI) (3T Achieva, Philips Medical Systems, Universitair Ziekenhuis Brussel, Brussels, Belgium) were taken of J Hand Surg Am.
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
FIGURE 2: A Harvesting en bloc of the MC1 and trapezium (Trap). B The DRL is delineated in green adjacent to the posterior oblique ligament (POL). During our dissections, the DRL appeared like a continuous sheet at the dorsoradial side of the joint; we did not observe a DCL as a distinct ligament. C The AOL is indicated in blue.
(ImageJ 1.45s, W. Rasband, National Institutes of Health, Washington, DC). Lengths were measured between the deep osseous attachments of the ligaments. Several measurements were obtained on each sequence, and the arithmetic mean of all measurements per ligament was calculated.
for each specimen. This resulted in 26 separate boneligament-bone complexes used to evaluate the material properties of the 2 ligaments (13 AOL and 13 DRL) (Fig. 3). These samples were mounted in a material testing rig (LM1-TestBench, Bose Corp., Eden Prairie, MN), and cyclic, displacement-controlled tests (2 Hz; 40 cycles; preconditioning at 0.5 N) were executed on each sample until a maximal loading of 150 N (7/26), until ligament rupture (12/26), bone rupture (5/26), or simultaneous ligament and bone rupture (2/26)15,23 (Fig. 4). Throughout the experiment, the sample was kept moist with saline. The obtained force-displacement curves were used to calculate stiffness and hysteresis of each sample. The stiffness was calculated as the slope of the linear part of the force-displacement curve in cycle 20 to account for conditioning of the ligament in the first cycles. The highest recorded stiffness obtained in the different subsequent tests was reported for each ligament. The hysteresis was calculated as the difference between the ascending and the descending curves (expressed in percentages). Stiffness was calculated to assess the stabilizing role of both ligaments, whereas hysteresis indicated the energy loss during loading.
Dissection technique and measurements Before dissection, the hands were thawed at room temperature. Exposure of the TMC joint was achieved through a combined dorsal and volar approach, reflecting all anatomical structures until reaching the deep ligament layer. The dissection was performed under 4.5 loupe magnification by a fully trained hand surgeon (P.D.A.). The origin, insertion, and fiber orientation of both the DRL and the AOL were identified based on anatomical descriptions of Berger.22 Length and width of the ligaments were measured in a position of in situ maximal passive tension as described by Bettinger et al12 with a digital caliper (CDCP30PMX, Mitutoya, Kawasaki, Japan; 0.01 mm). Sample preparation and material testing The MC1 and trapezium were harvested en bloc with both ligaments attached in each cadaver hand (Fig. 2). All ligaments except for the DRL and AOL were removed before material testing. An ultrasonic bone saw was used to sagittally cut the bones in a MC1AOL-trapezium and MC1-DRL-trapezium complex J Hand Surg Am.
Statistical analysis All data are reported as mean SD for the DRL and AOL, respectively. Pairwise Wilcoxon signed rank r
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
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FIGURE 3: A Preparation of the samples prior to mounting in the material tester. Shown are B MC1-AOL-Trap (blue) and MC1-DRLTrap (green) complexes and C a close view of the articular surfaces of the TMC joint.
FIGURE 4: A Bone blocks are filled with epoxy to provide extra strength to the bone. B Asterisk shows the ligament rupture.
tests were used to compare the length measurements obtained via MRI and via dissection and to compare the dimensions and material properties between both ligaments. Wilcoxon tests were chosen because not all obtained measurements displayed a clearly normal distribution. Significance was set at P of .05.
originates from the dorsoradial tubercle of the trapezium and inserts onto the dorsal edge of the base of MC1 (Fig. 5). The length of the DRL obtained via MRI amounted on average to 10.0 mm (SD ¼ 1.1 mm) versus 12.9 mm (SD ¼ 2.1 mm) obtained during dissection. The average thickness of the DRL was 1.1 mm (SD ¼ 0.2 mm) and the average width was 12.1 mm (SD ¼ 1.6 mm) (Tables 3, 4 and 5). The AOL is located just beneath the thenar muscles and is intimately linked to them. The AOL originates from the volar tubercle of the trapezium and inserts across the volar ulnar tubercle (palmar beak) of the first metacarpal (Fig. 6). In our dissections, we consistently found a single layer with a thin and fragile structure. The length of the AOL measured via MRI gave an average length of 12.2 mm (SD ¼ 2.1 mm), and the length obtained during dissection amounted on
RESULTS Anatomical description and dimensions of the ligaments Both ligaments were identified in all 13 unfixed hands using the principles of Berger.22 The DRL is covered on its dorsoradial side by the abductor pollicis longus, which attaches distally on the lateral side of the first metacarpal and is located just radially to the posterior oblique ligament, which is immediately adjacent to the DRL. The DRL J Hand Surg Am.
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
FIGURE 5: Macroscopic anatomy of the DRL as observed during detailed dissection, in flexion A and extension B of the thumb.
TABLE 3.
Length Measurements Obtained via MRI and Dissection for DRL and AOL DRL
AOL
MRI Length (mm)
Dissection Length (mm)
MRI Length (mm)
Dissection Length (mm)
622R
10.0
17.4
14.0
18.8
624R
10.0
13.3
14.3
13.5
624L
9.0
12.5
14.1
15.0
628R
11.6
13.1
13.2
13.5
628L
11.5
12.1
12.4
13.9
632R
10.3
12.4
10.7
12.8
635L
8.5
11.4
12.2
10.9
636L
9.2
14.5
10.8
11.1
639L
9.7
13.5
7.7
12.1
Mean
10.0
12.9
12.2
13.0
1.0
2.1
2.1
2.6
Sample
SD %RSD
11
17
18
20
%RSD ¼ relative SD (percentage).
average to 13.0 mm (SD ¼ 2.6 mm). The average thickness of the AOL was 0.6 mm (SD ¼ 0.1 mm), and average width was 13. 6 mm (SD ¼ 2.6 mm) (Tables 3, 4, and 5). Statistical analysis of the anatomical data demonstrated a significant difference between the length of the DRL obtained via MRI and during dissection (W ¼ 0; P < .005). The methods did not result in a significantly different length measurement for the AOL (W ¼ 37; P ¼ .1). The MRI method was considered to give the most accurate and reproducible measurement of ligament length and thickness because MRI allows exact and precise visualization of the footprint of the ligament on bone and was, therefore, used in further analysis. Comparison of the MRI dimensions of the DRL and the AOL indicated that the DRL was significantly shorter, thicker, and narrower than the AOL.
DRL was 89 N/mm (SD ¼ 21 N/mm) and of the AOL was 65 N/mm (SD ¼ 30 N/mm). The hysteresis of the DRL amounted on average to 25% (SD ¼ 3%) and 21% (SD ¼ 4%) for the AOL (Tables 4 and 5). Statistical analysis of the data demonstrated the DRL to be significantly stiffer than the AOL (W ¼ 78; P < .05), with a significantly higher hysteresis (W ¼ 66; P < .05) (Tables 4 and 5). DISCUSSION Functional significance of the volar and dorsal ligaments To date, strong importance has been given to the AOL in providing TMC joint stability and in restraining dorsoradial subluxation. Our findings suggest, however, that at least equal importance should be given to the stiffer and thicker DRL, a finding that is also supported by recent biomechanical studies. The longstanding importance given to the AOL is upheld by the success of surgical procedures that include AOL reconstruction.8,24e26 In 1973, Eaton and Littler2 described the dorsal ligament as a thin and poorly defined structure and posited that it contributed
Material properties of the ligaments Force-elongation curves of each DRL and AOL sample are represented in Figure 7. The average stiffness of the J Hand Surg Am.
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AOL AND DRL ANATOMY AND MECHANICAL PROPERTIES
TABLE 4.
Dimensions and Material Properties of the DRL
Specimens
Length* (mm)
Thickness* (mm)
Width (mm)
S (MPa)
H (%)
624R
10.0
1.2
10.9
79
27
624L
9.0
1.3
11.9
76
622R
10.0
1.2
14.4
97
24
628L
11.5
1.2
11.3
107
21
635L
8.5
1.1
11.9
96
23
639L
9.7
0.8
11.3
52
32
636L
9.2
0.9
11.4
87
25
632R
10.3
1.1
10.2
73
22
628R
11.6
1.2
10.7
140
24
633L
12.3
91
26
633R
15.8
100
24
655L
11.3
78
26
655R n
11.5
81
23
9
13
13
13
10.0
1.1
12.1
89
25
1.0
0.2
1.6
21
3
9
Mean SD H, hysteresis; S, stiffness. *MRI measurements.
TABLE 5.
Dimensions and Material Properties of the AOL
Specimens
Length* (mm)
Thickness* (mm)
Width (mm)
S (MPa)
H (%)
624R
14.3
0.7
14.3
60
19
624L
14.1
0.9
12.6
23
24
622R
14.0
0.7
20.5
79
22
628L
12.4
0.6
13.8
58
25
635L
12.2
0.6
10.2
25
22
639L
7.7
0.4
12.8
109
13
636L
10.8
0.6
13.6
65
22
632R
10.7
0.7
12.7
68
15
628R
13.2
0.6
13.5
105
25
633L
12.3
81
19
633R
15.2
102
24
655L
11.9
33
23
655R
13.4
38
23
n Mean SD
9
13
13
13
12.2
9
0.6
13.6
65
21
2.1
0.1
2.6
30
4
H, hysteresis; S, stiffness. *MRI measurements.
little to the stability of the joint. The AOL, however, was considered as the key structure in maintaining thumb stability. In 1991, Pellegrini27 suggested a direct correlation between the condition of the articular J Hand Surg Am.
surfaces of the TMC joint and the integrity of the AOL, supporting the importance of the AOL in articular wear. Pellegrini et al28 also demonstrated that detachment or laxity of the AOL leads to dorsal r
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FIGURE 6: Macroscopic anatomy of the AOL as observed during detailed dissection, in flexion A and extension B of the thumb.
FIGURE 7: Force-elongation curves of A the DRL and B AOL samples. Each loop represents a different sample.
translation of MC1 on the trapezium in lateral pinch. Imaeda et al29 suggested that TMC joint stability is provided by the AOL combined with secondary support from the intermetacarpal and ulnar collateral ligaments. Based on these findings, de la Caffinière30 recommended a posterior approach of the TMC joint in total joint arthroplasty to preserve the anterior ligaments and their stabilizing function. The importance of the anterior ligaments has, however, been challenged by several studies. Strauch and colleagues13 pointed to the DRL as the primary restraint to dorsoradial subluxation in traumatic dislocations of the TMC joint. In a biomechanical study, Van Brenk et al14 confirmed the role of the DRL as the most important ligament in preventing dorsoradial subluxation and advocated preserving or reconstructing it in TMC joint surgery. Bettinger et al12 recognized that the AOL is thin, weak, and translucent whereas the DRL is the shortest, broadest, and thickest TMC joint ligament. More recently, Nanno and colleagues10 confirmed that the DRL was the thickest ligament attached to the trapezium and suggested that the DRL should contribute substantially to TMC joint stability. However, the importance of a ligament cannot accurately be inferred solely from dimensions and position, because its stabilizing potential is largely determined by its material properties. In 2000, Bettinger et al15 determined the relative stiffness and strength of all ligaments surrounding the J Hand Surg Am.
TMC joint. The DRL was the strongest and stiffest ligament stabilizing the TMC joint, whereas the AOL was relatively weak and compliant and, therefore, identified as a poor stabilizer of the TMC joint. In 2007, Colman et al11 generated conflicting data with the earlier work of Pellegrini in a biomechanical cadaver study.1,28 After random transsection of the AOL or DRL, the DRL proved to be more important than the AOL in providing stability and preventing dorsoradial translation of the base of MC1. Finally, 2 recent studies of the TMC joint ligaments conducted by Ladd and colleagues16,17 also challenged the primary importance of the AOL. They consistently identified the AOL as a thin, capsular tissueelike structure with low cellularity, inferring it would be a poor stabilizer of the TMC joint. These studies10,11,14e16 confirmed earlier suggestions of Strauch and colleagues14,18 that the DRL, and not the volar ligaments, is the primary restraint to dorsal translation of the TMC joint, a finding supported by the higher stiffness of the DRL compared with the AOL as demonstrated in our study and by Bettinger et al.15 Whereas Bettinger et al12,15 provided a comprehensive overview of the ligaments surrounding the TMC joint, our study specifically focused on the differences between the DRL and the AOL, in terms of both anatomy and material properties, in order to infer which ligament should be preserved and/ or reconstructed to achieve joint stability. Furthermore, r
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we did not find clear evidence that the AOL is present as 2 distinct structures (superficial and deep) as described in previous studies.12,27 Macroscopically, we found the AOL to be a poorly defined, diaphanous, and capsular-like structure.
REFERENCES 1. Pellegrini VD Jr. Pathomechanics of the thumb trapeziometacarpal joint. Hand Clin. 2001;17(2):175e184, viieviii. 2. Eaton RG, Littler JW. Ligament reconstruction for painful thumb carpometacarpal joint. J Bone Joint Surg Am. 1973;55(8):1655e1666. 3. Kuhlmann JN. Importance of the posteromedial trapeziometacarpal ligamentous complex. Chir Main. 2001;20(1):31e47. 4. Armstrong AL, Hunter JB, Davis TR. The prevalence of degenerative arthritis of the base of the thumb in postmenopausal woman. J Hand Surg Br. 1994;19(3):340e341. 5. Winzeler S, Rosenstein BD. Occupational injury and illness of the thumb. Causes and solutions. AAOHN J. 1996;44(10):487e492. 6. Haara M, Heliovaara M, Kroger H, et al. Osteoarthritis in the carpometacarpal joint of the thumb. Prevalence and associations with disability and mortality. J Bone Joint Surg Am. 2004;86(7): 1452e1457. 7. Court-Brown CM, Caesar B. Epidemiology of adult fractures: a review. Injury. 2006;37(8):691e697. 8. Burton RI, Pellegrini VD Jr. Surgical management of basal joint arthritis of the thumb. Part II. Ligament reconstruction with tendon interposition arthroplasty. J Hand Surg Am. 1986;11(3):324e332. 9. Teissier J. Lateral approach: the royal way for the trapezo-metacarpal prosthesis. Chir Main. 2011;30:S95eS97. 10. Nanno M, Buford WL Jr, Patterson RM, Andersen CR, Viegas SF. Three-dimensional analysis of the ligamentous attachments of the first carpometacarpal joint. J Hand Surg Am. 2006;31(7):1160e1170. 11. Colman M, Mass DP, Draganich LF. Effects of the deep anterior oblique and dorsoradial ligaments on trapeziometacarpal joint stability. J Hand Surg Am. 2007;32(3):310e317. 12. Bettinger PC, Linscheid RL, Berger RA, Cooney WP, An K-N. An anatomic study of the stabilizing ligaments of the trapezium and trapeziometacarpal joint. J Hand Surg Am. 1999;24(4):786e798. 13. Strauch RJ, Behrman MJ, Rosenwasser MP. Acute dislocation of the carpometacarpal joint of the thumb: An anatomic and cadaver study. J Hand Surg Am. 1994;19(1):93e98. 14. Van Brenk B, Richards RR, Mackay MB, Boynton EL. A biomechanical assessment of ligaments preventing dorsoradial subluxation of the trapeziometacarpal joint. J Hand Surg Am. 1998;23(4):607e611. 15. Bettinger P, Smutz W, Linscheid R, Cooney W, An K-N. Material properties of the trapezial and trapeziometacarpal ligaments. J Hand Surg Am. 2000;25(6):1085e1095. 16. Ladd AL, Lee J, Hagert E. Macroscopic and microscopic analysis of the thumb carpometacarpal ligaments. A cadaveric study of ligament anatomy and histology. J Bone Joint Surg Am. 2012;94(16):1468e1477. 17. Zhang AY, Van Nortwick S, Hagert E, Ladd AL. Thumb carpometacarpal ligaments inside and out: a comparative study of arthroscopic and gross anatomy from the Robert A. Chase Hand and Upper Limb Center at Stanford University. J Wrist Surg. 2013;2(1):55e62. 18. Strauch RJ, Rosenwasser MP, Behrman MJ. A biomechanical assessment of ligaments preventing dorsoradial subluxation of the trapeziometacarpal joint. J Hand Surg Am. 1999;24(1):198e199. 19. Van Heest AE, Kallemeier P. Thumb carpal metacarpal arthritis. J Am Acad Orthop Surg. 2008;16(3):140e151. 20. Cardoso FN, Kim HJ, Albertotti F, Botte MJ, Resnick D, Chung CB. Imaging the ligaments of the trapeziometacarpal joint: MRI compared with MR arthrography in cadaveric specimens. AJR Am J Roentgenol. 2009;192(1):W13eW19. 21. Pike J, Koulouris G, van Wettering N, Hoy G. MR imaging of thumb carpometacarpal joint ligament injuries. J Hand Surg Br. 2004;29(1): 46e54. 22. Berger RA. The anatomy of the ligaments of the wrist and distal radioulnar joints. Clin Orthop Relat Res. 2001;383:32e40. 23. Vereecke EE, Channon AJ. The role of hind limb tendons in gibbon locomotion: springs or strings? J Exp Biol. 2013;216(Pt 21):3971e3980. 24. Eaton RG, Lane LB, Littler JW, Keyser JJ. Ligament reconstruction for the painful thumb carpometacarpal joint: A long-term assessment. J Hand Surg Am. 1984;9(5):692e699.
Limitations of the study There are some critical considerations to be made linked to the sample composition and experimental procedure of this study. The mean age of our specimens was relatively high (74 y) and may have had an impact on ligament integrity, but it is comparable with those of other studies.12,27 Subjects with advanced stages of osteoarthritis were excluded to ensure sampling of normal ligamentous structures, representative for normal TMC anatomy (Table 2). Two different methods were used to measure length and thickness of the ligaments. Statistical analysis of our results indicated a significant difference between length measurements obtained via MRI and those obtained with a caliper. MRI was selected as the most accurate method because we noted difficulties in identifying the exact location of the ligament insertions during dissection, whereas precise identification of these ligaments insertions was possible on high resolution MRI. In addition, MRI allowed in situ measurement of the ligament dimensions in a resting thumb position. CLINICAL RELEVANCE Stability of the TMC joint relies on muscles, tendons, and ligaments crossing the joint. Laxity of the ligaments has been proposed as a mechanism for the development of osteoarthritis of the TMC joint.31 Understanding ligament function is thus of primordial importance in optimizing surgical interventions. Preservation or reconstruction of all ligaments is not always possible during surgery. A choice has then to be made to sacrifice or reconstruct certain ligaments or ligament functions. Our results point to significant differences in dimensions and material properties between the AOL and the DRL and support the findings of the most recent studies that underline the functional importance of the thick DRL.10,11,14e16,18 Our findings suggest that Eaton and Littler’s concept, relying on the volar ligament,10 should be reconsidered and that the importance of the DRL should be taken into account when planning surgeries with an extensive (ie, noneligament sparing) approach or ligament reconstruction of the TMC joint. J Hand Surg Am.
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25. 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. 26. Thompson JS. Surgical treatment of trapeziometacarpal arthrosis. Adv Orthop Surg. 1986;10:105. 27. Pellegrini VD Jr. Osteoarthritis of the trapeziometacarpal joint: the pathophysiology of articular cartilage degeneration. I. Anatomy of the aging joint. J Hand Surg Am. 1991;16(6):967e974. 28. Pellegrini VD Jr, Olcott CW, Hollenberg G. Contact patterns in the trapeziometacarpal joint: the role of the palmar beak ligament. J Hand Surg Am. 1993;18(2):238e244. 29. Imaeda T, An KN, Cooney W III. Functional anatomy and biomechanics of the thumb. Hand Clin. 1992;8(1):9e15. 30. de la Caffinière JY. Longevity factors in total trapezometacarpal prosthèses. Chir Main. 2001;20(1):63e67. 31. Jonsson H, Valtysdottir S, Kjartansson O, Brekkan A. Hypermobility associated with osteoarthritis of the thumb base: a clinical and radiological subset of hand osteoathritis. Ann Rheum Dis. 1996;55(8):540e543. 32. von Lanz TR, Wachsmuth W. Das sattelgelenk des daumes, articulatio carpo-metacarpes pollicis. In: Praktische anatomie: ein lehrund
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hilfsbuch der anatomischen grundlagen ärztlichen Handelns. Berlin: Springer-Verlag; 1959:261. Spinner M, ed. Kaplan’s Functional and Surgical Anatomy of the Hand. 2nd ed. Philadelphia: JB Lippincott; 1965:121e124. Weitbrecht J, Kaplan EB. Syndesmology. Philadelphia: WB Saunders; 1969. Eaton RG, Littler JW. A study of the basal joint of the thumb. Treatment of its disabilities by fusion. J Bone Joint Surg Am. 1969;51(4):661e668. Rouvière H, Delmas A. Anatomie Humaine. Descriptive, topographique et fonctionnelle. Paris: Elsevier-Masson; 1970. Pieron A. The mechanism of the first carpometacarpal (CMC) joint. An anatomical and mechanical analysis. Acta Orthop Scand. 1973;148: 1e104. Imaeda T, An K-N, Cooney WP III, Linscheid R. Anatomy of trapeziometacarpal ligaments. J Hand Surg Am. 1993;18(2):226e231. Bojsen-Møller F. Osteoligamentous guidance of the movements of the human thumb. Am J Anat. 1976;147(1):71e80. Haines RW. The mechanism of rotation of the first carpo-metacarpal joint. J Anat. 1944;78(Pt 1e2):44e46. Napier J. Hands. New York: Pantheon; 1980:71.
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