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Published online before print February 1, 2002, 10.1148/radiol.2223010466
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(Radiology 2002;222:763-770.)
© RSNA, 2002

Musculoskeletal Imaging

Pisotriquetral Joint: Assessment with MR Imaging and MR Arthrography1

Nicolas H. Theumann, MD, Christian W. A. Pfirrmann, MD, Christine B. Chung, MD, Gregory E. Antonio, MD, Debra J. Trudell, RA and Donald Resnick, MD

1 From the Department of Radiology, Veterans Administration Medical Center, 3350 La Jolla Village Dr, San Diego, CA 92161 (N.H.T., C.W.A.P., C.B.C., G.E.A., D.J.T., D.R.); and Department of Radiology, CHUV, Lausanne, Switzerland (N.H.T.). Received February 15, 2001; revision requested April 9; final revision received September 10; accepted September 19. Supported by the Swiss Radiological Society and the Swiss National Science Foundation. Address correspondence to D.R. (e-mail: dresnick@ucsd.edu).


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
PURPOSE: To evaluate magnetic resonance (MR) imaging and MR arthrographic findings in the pisotriquetral joint (PTJ) and their contribution to assessment of PTJ osteoarthritis.

MATERIALS AND METHODS: Images of 22 fresh human cadaveric PTJs were obtained with both conventional and arthrographic MR techniques. The MR appearances of all intraarticular and periarticular structures were analyzed and correlated with anatomic slices. Two readers graded visibility of anatomic structures and severity of joint abnormalities. Differences in the visibility ratings at standard MR imaging and at MR arthrography were calculated. Association between the type of pisiform insertion of ligament or muscle with cartilaginous abnormalities of the PTJ was assessed. The association between cartilaginous lesions and osteoarthritic changes was calculated.

RESULTS: The tendon sheath, the fibrous capsule, and cartilaginous surfaces were better visualized at MR arthrography than at MR imaging. Pisohamate and pisometacarpal ligaments were slightly better seen on MR arthrograms. Tendons, muscles, and retinacular structures were well demonstrated at both conventional MR and MR arthrography. Cartilaginous lesions and osteophytes were easily identified and were detected more often in the pisiform bone than in the triquetral bone. Communication of the PTJ with the radiocarpal joint was noted in 18 (82%) of 22 wrists.

CONCLUSION: MR imaging and/or MR arthrography allows visualization of all anatomic structures of the PTJ. MR arthrography improves visualization of findings of osteoarthritis.

© RSNA, 2002

Index terms: Arthritis, 433.711 • Magnetic resonance (MR), arthrography, 433.121419 • Wrist, arthritis, 433.711 • Wrist, MR, 433.1214


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Pain and tenderness are common in the palmar and ulnar aspects of the wrist in the area of the pisiform bone (1). When chronic, this pain may be due to tendinopathy at the insertion site of the ulnar flexor tendon, to carpal fractures, or to osteoarthritis of the pisotriquetral joint (PTJ). The PTJ is the second most common site of osteoarthritis in the wrist after the scaphotrapezial joint, if the first carpometacarpal joint is excluded (2). Instability of the PTJ is a recognized complication of osteoarthritis of this joint (3). Degenerative changes of the PTJ often remain undiagnosed at clinical and radiographic evaluation (3). Although they are not usually performed, several methods for imaging the PTJ have been proposed. A profile view can be obtained when the hands are placed in 30° of supination (4), allowing evaluation of the joint and adjacent bone. Arthrography of the PTJ has also been used alone (5) or in combination with radiocarpal joint arthrography (6) to evaluate intraarticular abnormalities of the PTJ. Computed tomography (CT) and CT arthrography allow more precise visualization of this joint (7). These imaging methods offer more thorough analysis of the articulation but are limited because of their lack of soft-tissue contrast.

A potential role of magnetic resonance (MR) imaging in the assessment of abnormalities of the PTJ has been explored in a few investigations (8,9), although to our knowledge no report exists that details the possible role of MR arthrography in the evaluation of the PTJ. The purpose of our study was to evaluate the MR imaging and MR arthrographic findings of the PTJ and the contribution of these examinations to the assessment of osteoarthritis of this joint.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 
Cadavers and Specimen Preparation
Twenty-two fresh human hands were harvested from 17 nonembalmed cadavers (12 women, five men; age range at death, 45–90 years; mean age at death, 75 years) collected over a period of 3 months. The specimens were derived from arms cut through the distal portions of the radius and ulna. The specimens were immediately deep-frozen at -40°C (Forma Bio-Freezer; Forma Scientific, Marietta, Ohio). All specimens were allowed to thaw for 24 hours at room temperature prior to routine radiography. Posteroanterior and lateral projections with 30° of supination of the wrist were obtained prior to MR imaging to exclude gross abnormalities such as fracture or dislocation.

MR Imaging
MR imaging studies were obtained with a 1.5-T MR imaging unit (Signa; GE Medical Systems, Milwaukee, Wis) with either a dedicated wrist coil for assessment of the PTJ with the wrist in neutral position (n = 22) or a wrap coil for assessment of the PTJ with the wrist in extension and in the flexed position (n = 7). Each hand was placed in a prone position in the center of the gantry. Four sequences were performed with the wrist in neutral position. These included transverse, coronal, and sagittal T1-weighted spin-echo sequences (repetition time msec/echo time msec, 500/12; section thickness, 2 mm; interspace, 0.5 mm; number of signals acquired [NSA], two; field of view [FOV], 6 x 6 cm; matrix, 512 x 256; acquisition time, 4 minutes 24 seconds for each sequence). Thereafter, sagittal T1-weighted spin-echo images with fat suppression (500/12; section thickness, 2 mm; interspace, 0.5 mm; NSA, two; FOV, 6 x 6 cm; matrix, 512 x 256; acquisition time, 6 minutes 40 seconds) were obtained.

MR Arthrography
With fluoroscopic guidance, the wrist was placed in a lateral position (with the thumb down and the wrist flexed) and was moved gradually into supination until the PTJ was well delineated. A 22-gauge (0.7 x 40.0-mm) needle was inserted directly through the skin from an ulnar approach and was advanced into the PTJ. The position of the tip of the needle was verified with a test injection of a small amount of iohexol (Omnipaque 350; Nycomed Amersham, Princeton, NJ), an iodinated contrast material. Subsequently, approximately 1–3 mL of a solution of 1 mol/L gadopentetate dimeglumine (Magnevist; Schering, Berlin, Germany) diluted in 250 mL of saline and mixed with an equal amount of iodinated contrast agent (Omnipaque 350) was injected in the joint with fluoroscopic control. The injections were performed by two of the authors (N.H.T., C.W.A.P.). The exact volume injected depended on the amount required to achieve joint distention without encountering substantial pressure, to avoid capsular rupture. If a communication with the radiocarpal joint or the distal radioulnar joint was present, 4–6 mL of the solution was added. Conventional lateral and posteroanterior radiographs were then obtained to document the presence of intraarticular contrast.

MR imaging was performed within 30 minutes following injection of the contrast agent. With the wrist in neutral position (ie, in pronosupination and radioulnar flexion) and with the elbow flexed at 90°, MR sequences (not including the sagittal fat-saturated T1-weighted sequence) were performed that were identical to the first three sequences performed before opacification of the joint. Coronal fast three-dimensional gradient-recalled-echo images (50/12; section thickness, 0.7 mm; interspace, 0; NSA, two; FOV, 7 x 7 cm; flip angle, 60°; matrix, 512 x 256; acquisition time, 10 minutes 40 seconds) were then obtained. In seven of the wrists, sagittal T1-weighted spin-echo MR images (500/12; section thickness, 2 mm; interspace, 0.5 mm; NSA, three; FOV, 9 x 9 cm; matrix, 512 x 256; acquisition time, 6 minutes 30 seconds) were also acquired in positions of maximum passive flexion and passive extension.

Radiologic-Anatomic Correlation
After imaging, all cadaveric specimens were immediately frozen in neutral positions at -40°C for at least 24 hours and were subsequently sliced with a band saw into 2-mm-thick slices (corresponding to the thickness of the MR images) along one of the following imaging planes, according to lines drawn on the specimen at the time of imaging: coronal (n = 7), sagittal (n = 7), or transverse (n = 8). Photographs of each slice were obtained.

The MR images and anatomic slices were simultaneously interpreted in consensus by two musculoskeletal radiologists (N.H.T., C.W.A.P.) Intra- and periarticular structures were identified according to descriptions in the literature (10–12); their appearances on MR images were correlated with their appearances in the anatomic slices. Data were recorded for the following articular structures: (a) the musculotendinous structures (of the ulnar flexor tendon and the abductor muscle of the little finger) (Fig 1); (b) the ligamentous structures (the pisohamate ligament, the pisometacarpal ligament [Fig 1], the tendon sheath of the ulnar extensor tendon associated with the dorsal carpal ligament, the fibrous capsule, and the transverse carpal ligament [Fig 1], which is divided into two different fibrous bands on its ulnar side: the ligamentum carpi palmare and the ligamentum flexorum, both of which delimit the Guyon canal) (1); and (c) the articular surfaces of the pisiform bone and the triquetral bone.



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  		Figure 1. Right-hand palmar view of the anatomic structures in the region of the pisiform bone.

 
The appearance of each normal structure on MR images and on MR arthrograms was graded on a continuous scale from 1 to 4 (1, nonvisible; 2, visible but nonanalyzable; 3, visible and analyzable; and 4, excellent visualization with sharp outlines). The visibility was rated as good when the average of these scores was equal to or greater than 3.5. Differences in the visibility ratings between standard MR imaging and MR arthrography were calculated with the Wilcoxon signed rank test (13); the significance level was P < .05.

On the basis of analysis of the MR images (not including the MR arthrographic images), the same two observers reached a consensus regarding the following measurements: The width and thickness of the ulnar flexor tendon were measured on transverse images 3 mm proximal to its insertion in the pisiform bone. The length, width, and thickness of the pisohamate ligament and the pisometacarpal ligament were measured in the midsubstance of the ligaments. The ligamentous anatomy at the distal aspect of the pisiform bone was categorized into three different types according to the classification proposed by Yamaguchi et al (12). Type A corresponded to a situation in which the pisohamate ligament and the pisometacarpal ligament inserted on the palmar and distal aspects of the pisiform bone, and type B corresponded to the insertion of the pisohamate ligament on the radial side of the pisiform bone, deep to the insertion of the pisometacarpal ligament. Type C anatomy was similar to type B anatomy but with an additional ligamentous slip between the pisometacarpal ligament and the distal aspect of the hook of the hamate bone. The sites of proximal attachment of the abductor muscle of the little finger were also recorded as either being restricted to the pisiform bone or as including partial extension to the pisometacarpal ligament. Any association between the insertion type of the pisohamate ligament, pisometacarpal ligament, or abductor muscle of the little finger and cartilaginous abnormalities of the PTJ was assessed with the Mann-Whitney test (13).

On the basis of the MR images and the MR arthrograms, the same two observers evaluated the following features in consensus: The shape of the articular surfaces of the pisiform bone and the triquetral bone was recorded as flat, concave, or convex in the transverse and sagittal planes. The degree of osteoarthritic chondral changes on both articular surfaces was rated as follows: Grade 0 corresponded to normal cartilage, grade 1 corresponded to irregularity of the surface of the cartilage, grade 2 corresponded to cartilaginous damage or thinning that did not extend to the subchondral bone, grade 3 corresponded to lesions that reached the subchondral bone without osseous abnormalities, and grade 4 corresponded to cartilaginous lesions that extended to the subchondral bone with associated osseous abnormalities. The location of the chondral lesions was recorded as central, peripheral, or global. The presence of osteophytes and their location (proximal, distal, medial, or lateral) in the pisiform bone and in the triquetral bone were also noted. The maximal sizes of the articular surfaces of these bones were measured in transverse and sagittal planes. The maximal lengths of the proximal and distal articular recesses were also measured in the sagittal plane. The presence of any communication between the PTJ and the radiocarpal joint was recorded. The distance between the center of the articular surface of the pisiform bone and the central articular surface of the triquetral bone in positions of flexion and extension of the wrist were measured; these measurements were used to indicate dorsoventral excursion. Associations between the cartilaginous lesions and the other osteoarthritic characteristics cited above were calculated with the Spearman rank test (13).


   RESULTS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
DISCUSSION
 REFERENCES
 
The results of the analysis of the MR studies are detailed in Tables 1–4.


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  		TABLE 1. Rating of Differences in Visibility between Standard MR Imaging and MR Arthrography

 

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  		TABLE 2. Measurements of Ulnar Flexor Tendon, Pisohamate Ligament, and Pisometacarpal Ligament

 

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  		TABLE 3. Characteristics of Articular Structures

 

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  		TABLE 4. Correlation between Articular Structure Measurements and Presence of Cartilaginous Lesions

 
Musculotendinous Structures
The tendon of the ulnar flexor muscle inserted in the proximal and palmar aspects of the pisiform bone in all cases. Some fibers of the ulnar flexor tendon generally extended beyond the pisiform bone and were continuous with the fibers of the pisohamate ligament and the pisometacarpal ligament (Fig 2). The ulnar flexor tendon could be well seen on both MR images and MR arthrograms. The mean tendinous width and thickness were 8.3 mm and 3.2 mm, respectively.



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  		Figure 2a. (a) Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the left pisiform bone with the wrist in extended position. The bulk of the fibers of the ulnar flexor tendon (straight arrow) insert on the proximal aspect of the pisiform bone (P). Additional strands extend over the pisiform bone to join the fibers of the pisohamate ligament (curved arrow). The pisohamate ligament extends from the palmar distal aspect of the pisiform bone (insertion type A) to the hook of the hamate bone (H). T = triquetral bone, U = ulna. (b) Coronal T1-weighted spin-echo (500/12) MR image of the pisiform bone (P). The ulnar nerve follows the shape of the left pisiform bone in the Guyon canal (arrowheads). Arrow = ulnar flexor tendon.

 


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  		Figure 2b. (a) Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the left pisiform bone with the wrist in extended position. The bulk of the fibers of the ulnar flexor tendon (straight arrow) insert on the proximal aspect of the pisiform bone (P). Additional strands extend over the pisiform bone to join the fibers of the pisohamate ligament (curved arrow). The pisohamate ligament extends from the palmar distal aspect of the pisiform bone (insertion type A) to the hook of the hamate bone (H). T = triquetral bone, U = ulna. (b) Coronal T1-weighted spin-echo (500/12) MR image of the pisiform bone (P). The ulnar nerve follows the shape of the left pisiform bone in the Guyon canal (arrowheads). Arrow = ulnar flexor tendon.

 
The abductor muscle of the little finger was well seen in all studies. Two different types of proximal insertion were observed. In 19 (86%) of 22 cases, the tendinous fibers arose from the pisiform bone and from the pisometacarpal ligament (Fig 3). In the remaining three (14%) of 22 cases, the fibers arose only from the pisiform bone.



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  		Figure 3. Coronal T1-weighted spin-echo (500/12) MR image of the right pisiform bone (P). The pisohamate ligament (straight arrow) extends from the distal aspect of the pisiform bone to the hook of the hamate bone (H). The abductor muscle of the little finger (curved arrows) inserts proximally on the pisiform bone and the pisometacarpal ligament (arrowheads).

 
Ligamentous Structures
The pisohamate ligament was visualized as a strong fibrous structure arising from the radial aspect of the distal pole of the pisiform bone (Fig 2). Type A insertions were noted in 14 (64%) of 22 cases, type B insertions were noted in eight (36%) of 22 cases, and no cases of type C insertions were observed. No association was observed between these two types of insertion and cartilaginous lesions of the pisiform bone (P = .428) or the triquetral bone (P = .804). The pisohamate ligament was significantly (P = .006) better visualized on MR arthrograms than on standard MR images (with mean visibility ratings of 4.0 and 3.4, respectively). Its average measurements were 7.3 mm in length, 6.6 mm in width, and 6.2 mm in thickness. It extended distally to the hook of the hamate bone.

The pisometacarpal ligament was visualized as a thinner and longer fibrous structure than the pisohamate ligament. In all cases, it arose from the distal aspect of the pisiform bone and extended to the bases of the fourth and fifth metacarpal bones. It coursed through the concavity along the ulnar aspect of the hook of the hamate bone (Fig 4); its average measurements were 10.2 mm in length, 3.3 mm in width, and 2.9 mm in thickness. A significant (P = .001) difference in visualization was noted between MR images and MR arthrograms (a mean visibility rating of 4.0 was obtained with MR arthrography, while a rating of 3.3 was obtained at conventional MR imaging).



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  		Figure 4a. (a) Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the pisiform bone (P) with the right wrist in extended position. The pisometacarpal ligament (arrowheads) extends from the palmar distal aspect of the pisiform bone to the base of the fifth metacarpal (MC5). Curved arrows = short flexor muscle of little finger, straight arrow = ulnar flexor tendon, T = triquetral bone. (b) Sagittal anatomic correlation of the pisiform bone with the right wrist in neutral position. The pisometacarpal ligament (arrowheads) extends from the palmar distal aspect of the pisiform bone (P) to the base of the fifth metacarpal (MC5). Arrow = ulnar flexor tendon, T = triquetral bone. (c) Transverse T1-weighted spin-echo (500/12) MR image of the distal row of the right carpus. The pisometacarpal ligament (arrowheads) courses through the concavity along the ulnar aspect of the hook of the hamate bone (curved arrow).

 


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  		Figure 4b. (a) Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the pisiform bone (P) with the right wrist in extended position. The pisometacarpal ligament (arrowheads) extends from the palmar distal aspect of the pisiform bone to the base of the fifth metacarpal (MC5). Curved arrows = short flexor muscle of little finger, straight arrow = ulnar flexor tendon, T = triquetral bone. (b) Sagittal anatomic correlation of the pisiform bone with the right wrist in neutral position. The pisometacarpal ligament (arrowheads) extends from the palmar distal aspect of the pisiform bone (P) to the base of the fifth metacarpal (MC5). Arrow = ulnar flexor tendon, T = triquetral bone. (c) Transverse T1-weighted spin-echo (500/12) MR image of the distal row of the right carpus. The pisometacarpal ligament (arrowheads) courses through the concavity along the ulnar aspect of the hook of the hamate bone (curved arrow).

 


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  		Figure 4c. (a) Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the pisiform bone (P) with the right wrist in extended position. The pisometacarpal ligament (arrowheads) extends from the palmar distal aspect of the pisiform bone to the base of the fifth metacarpal (MC5). Curved arrows = short flexor muscle of little finger, straight arrow = ulnar flexor tendon, T = triquetral bone. (b) Sagittal anatomic correlation of the pisiform bone with the right wrist in neutral position. The pisometacarpal ligament (arrowheads) extends from the palmar distal aspect of the pisiform bone (P) to the base of the fifth metacarpal (MC5). Arrow = ulnar flexor tendon, T = triquetral bone. (c) Transverse T1-weighted spin-echo (500/12) MR image of the distal row of the right carpus. The pisometacarpal ligament (arrowheads) courses through the concavity along the ulnar aspect of the hook of the hamate bone (curved arrow).

 
The sheath of the ulnar extensor tendon appeared in all cases as a thick fibrous band that blended with the dorsal carpal ligament and attached to the ulnar aspect of the pisiform bone (Fig 5). On the conventional MR images, the sheath of the ulnar extensor tendon was not well delineated. With MR arthrography, the visualization of this structure was facilitated (yielding a mean visibility rating of 4.0 versus the 1.3 obtained at conventional MR imaging).



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  		Figure 5a. (a) Transverse T1-weighted spin-echo (500/12) MR image of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (white arrow) is not well seen. The transverse carpal ligament lies over the carpal tunnel and inserts in the ulnar flexor tendon (black arrow) near the ligamentum carpi palmare (white arrowheads). (b) Transverse T1-weighted spin-echo (500/12) MR arthrogram of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (black arrow) is well visualized. The Guyon canal is delimited by the ligamentum carpi palmare (white arrowheads) and the ligamentum flexorum (curved white arrow). The thick white arrow points to the ulnar flexor tendon. Note the focal cartilage defect in the triquetral bone (upper open white arrow) and the global cartilage defect in the pisiform bone (lower open white arrow). (c) Transverse anatomic correlation of the first row of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (white arrow) is not well visualized. The transverse carpal ligament lies over the carpal tunnel and inserts on the ulnar flexor tendon (black arrow) near the ligamentum carpi palmare (white arrowheads).

 


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  		Figure 5b. (a) Transverse T1-weighted spin-echo (500/12) MR image of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (white arrow) is not well seen. The transverse carpal ligament lies over the carpal tunnel and inserts in the ulnar flexor tendon (black arrow) near the ligamentum carpi palmare (white arrowheads). (b) Transverse T1-weighted spin-echo (500/12) MR arthrogram of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (black arrow) is well visualized. The Guyon canal is delimited by the ligamentum carpi palmare (white arrowheads) and the ligamentum flexorum (curved white arrow). The thick white arrow points to the ulnar flexor tendon. Note the focal cartilage defect in the triquetral bone (upper open white arrow) and the global cartilage defect in the pisiform bone (lower open white arrow). (c) Transverse anatomic correlation of the first row of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (white arrow) is not well visualized. The transverse carpal ligament lies over the carpal tunnel and inserts on the ulnar flexor tendon (black arrow) near the ligamentum carpi palmare (white arrowheads).

 


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  		Figure 5c. (a) Transverse T1-weighted spin-echo (500/12) MR image of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (white arrow) is not well seen. The transverse carpal ligament lies over the carpal tunnel and inserts in the ulnar flexor tendon (black arrow) near the ligamentum carpi palmare (white arrowheads). (b) Transverse T1-weighted spin-echo (500/12) MR arthrogram of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (black arrow) is well visualized. The Guyon canal is delimited by the ligamentum carpi palmare (white arrowheads) and the ligamentum flexorum (curved white arrow). The thick white arrow points to the ulnar flexor tendon. Note the focal cartilage defect in the triquetral bone (upper open white arrow) and the global cartilage defect in the pisiform bone (lower open white arrow). (c) Transverse anatomic correlation of the first row of the right wrist. The dorsal carpal ligament (black arrowheads) inserts in the ulnar aspect of the pisiform bone. The fibrous capsule (white arrow) is not well visualized. The transverse carpal ligament lies over the carpal tunnel and inserts on the ulnar flexor tendon (black arrow) near the ligamentum carpi palmare (white arrowheads).

 
The fibrous capsule of the PTJ extended along the radial border of the triquetral bone to the ipsilateral border of the pisiform bone. It was not visible on the standard MR images (which yielded a mean visibility rating of 1.2 for this structure) but was well seen at MR arthrography with a mean visibility rating of 4.0 (Fig 5).

The transverse carpal ligament covered the carpal tunnel and divided into two ligaments on its ulnar side—the ligamentum carpi palmare and the ligamentum flexorum (Fig 5). The ligamentum carpi palmare extended over the proximal portion of the Guyon canal and inserted in the distal fibers of the ulnar flexor tendon. The ligamentum flexorum constituted the floor of the Guyon canal, and its insertion in the pisiform bone was more distal than that of the ligamentum carpi palmare.

Articular Structures
The pisiform bone articulated with the triquetral bone on an ovoid articulating surface, which was significantly better visualized with MR arthrography (with a mean visibility rating of 4.0 vs the 2.1 obtained at standard MR imaging). Cartilaginous lesions were observed in 20 (91%) of 22 cases (Figs 5b, 6). The mean grade of the cartilaginous lesions was 2.3, and these lesions were either peripheral (in 10 [50%] of 20 cases) or global (10 [50%] of 20 cases). No central lesions were observed. In 12 (55%) of 22 cases, one or more osteophytes were reported, which were usually proximal (in eight [67%] of 12 cases), distal (in seven [58%] of 12 cases), or both (in six [50%] of 12 cases). Less frequently (in five [42%] of 12 cases), lateral osteophytes were noted. In only one case was a medial osteophyte observed. There was no association between the size of the articular surface and the presence of cartilaginous lesions.



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  		Figure 6. Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the pisiform bone with the left wrist in flexed position. Much of the cartilage of the pisiform bone (black arrow) is absent. Note the movement of the midpoints (arrows) of the articular surfaces (arrowheads) of the pisiform bone and the triquetral bone (T). H = hamate bone, MC = fifth metacarpal, U = ulna.

 
The triquetral articular surface opposite the pisiform bone was also much better seen at MR arthrography, with a mean visibility rating of 4.0, than at standard MR imaging, which yielded a mean visibility rating of 2.0. Cartilaginous lesions were observed in 16 (73%) of 22 cases (Fig 5b). The mean grade of these lesions was 1.6, and the distribution of these lesions was either peripheral (in 13 [81%] of 16 cases) or, less frequently, global (in three [19%] of 16 cases). No central lesions were observed. An osteophyte was seen in only one case (5%) of the 22 cases, and its location was proximal. There was no association between the size of the articular surface and the presence of cartilaginous lesions.

The proximal recess of the PTJ was smooth and round (Fig 7), and this joint communicated with the radiocarpal joint in 18 (82%) of 22 cases. The mean maximal size of the proximal recess was 7.8 mm. The distal recess of the PTJ was much smaller and more rectangular, with the distal margin of the recess parallel to the distal aspect of the pisiform bone. The mean maximal size of the distal recess was 2.3 mm. No association was found between osteoarthritis and the size of the recesses. With regard to the dorsoventral excursion of the pisiform bone and triquetral bone, the mean separation between them was 2 mm in the proximal direction with the wrist in flexion (Fig 6) and 4.4 mm in the distal direction with the wrist in extension (Figs 2, 4).



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  		Figure 7. Sagittal T1-weighted spin-echo (500/12) MR arthrogram of the pisiform bone with the left wrist in neutral position. Note the round shape of the proximal recess of the PTJ (arrowheads) compared with the small and flat shape of the distal recess (small black arrows). Curved arrow = pisometacarpal ligament, large black arrow = ulnar flexor tendon, H = hamate bone, MC = fifth metacarpal, P = pisiform bone, T = triquetral bone.

 

   DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
REFERENCES
 
The exact function of the pisiform bone is not known, but aside from being a focal point of soft-tissue attachment in the medial aspect of the wrist, it is believed to act as a lever (much like the patella), increasing the force of wrist flexion (11). The effective function of the musculotendinous unit that attaches to the pisiform bone depends on the pisiform bone serving as a point of contact between the ulnar flexor muscle and the carpus through the pisohamate ligament and the pisometacarpal ligament during flexion of the wrist. The stability of the PTJ is dependent on two groups of opposing forces. On the ulnar side, the forces originate from the ulnar flexor muscle, the ulnar collateral ligament, the abductor muscle of the little finger, and, in part, the pisometacarpal ligament. On the radial side, the forces originate mainly from the pisohamate ligament and the transverse carpal ligament through the ligamentum carpi palmare and the ligamentum flexorum (1). However, the ulnar flexor tendon, the pisohamate ligament, and the pisometacarpal ligament are considered to be the main stabilizers of the pisiform bone (11). Soft-tissue failure can lead to distal pisiform bone dislocation (14) and instability of the PTJ. This instability may result in ulnar nerve irritation in the Guyon canal (15) and secondary osteoarthritis (3,16) related to increased motion of the PTJ.

The main supporting structures, such as the ulnar flexor tendon, the abductor muscle of the little finger, the ligamentum carpi palmare, and the ligamentum flexorum, were well visualized at both standard MR imaging and MR arthrography. The pisohamate ligament and the pisometacarpal ligament were substantially better identified at MR arthrography, probably because of the resultant distention of the PTJ after intraarticular injection. The fibrous capsule and the tendon sheath of the ulnar extensor tendon were either not visualized or were poorly visualized at MR imaging because of their contiguity with articular structures. These same structures, which are in contact with the PTJ, were well visualized at MR arthrography. The ulnar collateral ligament was not included in our analysis because it was not possible to identify this ligament as a distinct structure. Only some hypointense fibers blending with the tendon sheath of the ulnar extensor tendon were visible. The existence of the ulnar collateral ligament has been disputed in a previous report (17). Visualization of the Guyon canal (including the ligamentum carpi palmare and the ligamentum flexorum) was always rated as good because of a layer of fat around the neurovascular structures.

Osteoarthritis of the PTJ can develop insidiously or following an injury to the pisiform bone (18). In our study, there was a high frequency of cartilaginous lesions, with lesions of higher grade being more common in the pisiform bone than in the triquetral bone. Green reported similar results (19), but two studies (11,12) have demonstrated that the incidence of osteoarthritis in the pisiform bone and the incidence of osteoarthritis in the triquetral bone are approximately the same. In our study, the cartilaginous lesions were mainly peripheral in location and, less frequently, were global but were never isolated to the central portion of the joint. This observation is in agreement with the results reported by Yamaguchi et al (12).

Most of the osteophytes reported in our study were proximal or distal rather than medial or lateral. These observations suggest that osteoarthritis arises from movements of the joint that are more accentuated in a proximal-distal direction than in a mediolateral direction. These results are in agreement with those reported by Pevny et al (11), who demonstrated that proximal-distal motion, even under stable conditions, may lead to articular cartilage changes in the presence of soft-tissue imbalance. We did not find any correlation between the size of the proximal and distal recesses and the presence of osteochondral lesions. Our measurements of the joint surfaces are in agreement with the results of an anatomic study of 119 specimens by Beckers and Koebke (1). They found that in instances of osteoarthritis, the articular surfaces of the pisiform bone were 7% wider than normal and the articular surfaces of the triquetral bone were 3% wider. In our study, we did not find any association between the size of the articular surface and osteoarthritis of the PTJ. The frequency of communication between the PTJ and the radiocarpal joint (in 18 [82%] of 22 cases) in our study was similar to that reported in the literature (88%) (20). No association was found between this communication and the presence of cartilage disease.

The treatment of osteoarthritis of the PTJ is initially conservative and consists of local injections of steroid preparations (15). Excision of the pisiform bone is of benefit in restoring function and alleviating symptoms when conservative treatment is not sufficient (3,21).

There are four limitations to this study. First, clinical information was very limited, which is a common problem in cadaveric studies. Routine radiography, however, allowed exclusion of marked osseous abnormalities. Because osteoarthrosis tends to be characterized by asymmetric joint involvement, we have thus assumed the specimens to be independent of each other, although we acknowledge that 10 wrists were derived from the same five subjects. Second, the number of specimens was small, and resulting observations often did not reach statistical significance. Third, the use of cadaveric specimens allowed us to place the region of interest exactly in the center of the gantry, in the best position for imaging, a situation that is not always possible in patients. Clinically available equipment, however, was used in this study. Fourth, grading of structure visibility at MR is subjective. We used fewer but distinct differentiating categories in an attempt to improve on this.

In conclusion, MR imaging and MR arthrography provide good visualization of the anatomic structures in and around the PTJ. MR arthrography enhances the visualization of some of the structures around the PTJ and allows assessment of the chondral surfaces of the pisiform bone and the triquetral bone.


   FOOTNOTES
 
Abbreviations: FOV = field of view, NSA = number of signals acquired, PTJ = pisotriquetral joint

Author contributions: Guarantors of integrity of entire study, N.H.T., C.W.A.P., D.R., C.B.C., G.E.A.; study concepts, N.H.T., C.W.A.P., D.R.; study design, N.H.T.; literature research, N.H.T.; experimental studies, N.H.T., D.J.T.; data acquisition, N.H.T., C.W.A.P., D.J.T., C.B.C.; data analysis/interpretation, N.H.T., C.W.A.P., C.B.C.; statistical analysis, C.W.A.P.; manuscript preparation, N.H.T., C.B.C.; manuscript definition of intellectual content, N.H.T., D.R.; manuscript editing, D.R., C.B.C., G.E.A.; manuscript revision/review, D.R., G.E.A.; manuscript final version approval, D.R., N.H.T.


   REFERENCES
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS
 DISCUSSION
 REFERENCES
 

  1. Beckers A, Koebke J. Mechanical strain at the pisotriquetral joint. Clin Anat 1998; 11:320-326.
  2. Fischer E. Piso-triquetral arthrosis and the so-called pisiform secundarium. Radiologe 1988; 28:338-344[German].
  3. Belliappa PP, Burke FD. Excision of the pisiform in piso-triquetral osteoarthritis. J Hand Surg Br 1992; 17:133-136.
  4. Gardner-Thorpe D, Giddins GE. A reliable technique for radiographic imaging of the pisotriquetral joint. J Hand Surg Br 1999; 24:252.
  5. Weston WJ, Kelsey CK. Functional anatomy of the pisocuneiform joint. Br J Radiol 1973; 46:692-694.
  6. Resnick D, Andre M, Kerr R, Pineda C, Guerra J, Jr, Atkinson D. Digital arthrography of the wrist: a radiographic-pathologic investigation. AJR Am J Roentgenol 1984; 142:1187-1190.
  7. Cone RO, Szabo R, Resnick D, et al. Computed tomography of the normal soft tissues of the wrist. Invest Radiol 1983; 18:546-551.
  8. Pretorius ES, Epstein RE, Dalinka MK. MR imaging of the wrist. Radiol Clin North Am 1997; 35:145-161.
  9. Brown RR, Fliszar E, Cotten A, Trudell D, Resnick D. Extrinsic and intrinsic ligaments of the wrist: normal and pathologic anatomy at MR arthrography with three-compartment enhancement. RadioGraphics 1998; 18:667-674.
  10. Laude M, Le Gars D, Boudin G. Functional anatomy of the pisiform bone. Bull Assoc Anat (Nancy) 1979; 63:451-458[French].
  11. Pevny T, Rayan GM, Egle D. Ligamentous and tendinous support of the pisiform, anatomic and biomechanical study. J Hand Surg Am 1995; 20:299-304.
  12. Yamaguchi S, Viegas SF, Patterson RM. Anatomic study of the pisotriquetral joint: ligamentous anatomy and cartilagenous change. J Hand Surg Am 1998; 23:600-606.
  13. Siegel S, Castellan NJJ. Non parametric statistics for the behavioral sciences New York, NY: McGraw-Hill, 1988.
  14. Minami M, Yamazaki J, Ishii S. Isolated dislocation of the pisiform: a case report and review of the literature. J Hand Surg Am 1984; 9:125-127.
  15. Carroll RE, Coyle MP, Jr. Dysfunction of the pisotriquetral joint: treatment by excision of the pisiform. J Hand Surg Am 1985; 10:703-707.
  16. Seradge H, Seradge E. Pisotriquetral pain syndrome after carpal tunnel release. J Hand Surg Am 1989; 14:858-862.
  17. Taleisnik J, Gelberman RH, Miller BW, Szabo RM. The extensor retinaculum of the wrist. J Hand Surg Am 1984; 9:495-501.
  18. Paley D, McMurtry RY, Cruickshank B. Pathological conditions of the pisiform and pisotriquetral joint. J Hand Surg Am 1987; 12:110-119.
  19. Green DP. Pisotriquetral arthritis: a case report. J Hand Surg Am 1979; 4:465-467.
  20. Viegas SF, Patterson RM, Hokanson JA, Davis J. Wrist anatomy: incidence, distribution, and correlation of anatomic variations, tears, and arthrosis. J Hand Surg Am 1993; 18:463-475.
  21. Krag C. Osteoarthritis of the piso-triquetral articulation. Hand 1974; 6:181-184.



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