Imaging of Ulnar Sided Wrist Pain

Claire A. Coggins, MD

Department of Radiology, Virginia Commonwealth University, Main Hospital, 3rd Floor, Room 3-343, 1250 East Marshall Street, Richmond, VA 23298, USA

Ulnar-sided wrist pain has long been a diagnostic dilemma for both radiologists and hand surgeons. The small size of the anatomic structures, the diversity of disorders that can cause symptoms, and the high rate of asymptomatic findings at the ulnar aspect of the wrist are some of the factors that contribute to the difficulty of diagnosis and management in this region. In fact, ulnar wrist pain has been called the ''low back pain of the wrist'' [1]. Previous authors have described as many as 44 different entities to consider in the differential diagnosis of ulnar-sided wrist pain. This article focuses on the more common causes of pain in this region, including tears of the triangular fibrocartilage complex (TFCC), disorders of the distal radioulnar joint (DRUJ), tears of the lunotriquetral ligament, disorders of the extensor carpi ulnaris (ECU) tendon, disorders of the pisotriquetral joint, the impingement and im-paction syndromes, and ulnar wrist masses.

Anatomy, pathophysiology, and radiographic appearance of the various entities are discussed, including a brief review of treatment options. The goal of this article is to provide a concise approach to the diagnosis and imaging of a difficult but common problem.

Several different imaging modalities can be useful in the evaluation of ulnar-sided wrist pain. Conventional radiographs may demonstrate ulnar variance, carpal alignment, evidence of acute or remote trauma, and degenerative changes. CT is most useful for evaluation of DRUJ subluxation. Conventional arthrography (single compartment or three compartment) can detect complete and partial tears of the TFCC, as well as unidirectional communicating defects between the radiocarpal and midcarpal joints. MRI is useful for evaluation of ligament disruption, cartilage defects, tendon abnormalities, occult fractures, and avascular necrosis. MR arthrography combines the usefulness of conventional arthrography in detecting full-thickness TFCC tears with the ability to visualize marrow, ligaments, and soft tissues [2]. High-resolution MR with a dedicated wrist coil is essential in achieving the spatial resolution and

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IMAGING MODALITIES

signal-to-noise ratio to evaluate the small structures about the wrist [3]. Skeletal scintigraphy, although sensitive, is not specific and has limited use in evaluation of ulnar wrist pain. Likewise, sonography has limited use in this region and is used primarily for evaluation of ganglia or other masses.

TRIANGULAR FIBROCARTILAGE COMPLEX

The TFCC functions as a cushion for the ulnar carpus, absorbing approximately 20% of the axial load of the wrist, and as a major stabilizer of the DRUJ [4]. Palmer and Werner [5] defined the TFCC as composed of five structures:

Triangular fibrocartilage proper (articular disc) and volar and dorsal radioulnar

(RU) ligaments Ulnocarpal meniscus Ulnocarpal ligaments Ulnar collateral ligament (UCL] ECU tendon sheath

The triangular fibrocartilage proper and volar and dorsal RU ligaments arise from the ulnar border of the sigmoid notch of the radius and insert at the base of the ulnar styloid [4]. The dorsal and volar RU ligaments as well as the peripheral 20% of the articular disc are well vascularized. The inner 80% of the articular disc is avascular, as is its radial attachment [6,7]. On the volar aspect of the wrist, the volar RU ligament extends distally to the lunate and trique-trum as the ulnolunate and ulnotriquetral ligaments, respectively. The UCL extends from the base of the ulnar styloid to the hamate and to the fifth meta-carpal base. The ulnocarpal meniscus, or meniscus homologue, is a thickening of the UCL that passes distally to attach to the ulnar aspect of the triquetrum [4,5]. At the dorsal aspect of the wrist, the floor of the ECU tendon sheath passes distally to attach to the triquetrum, hamate, and fifth metacarpal base [8]. The interval between the meniscus homologue, the ulnotriquetral ligament, and the UCL is referred to as the prestyloid recess, which is an extension of the radiocarpal joint (Fig. 1) [9].

Tears of the TFCC can be either traumatic or degenerative. Traumatic injury is usually the result of hyperrotation of the forearm, distraction of the wrist, or axial loading. Traumatic tears of the TFCC tend to occur closer to the radius than degenerative tears (Fig. 2) [4].

Degenerative tears of the TFCC usually result from chronic loading on the ulnar aspect of the wrist and tend to occur in the thinner central portion of the articular disc [4].

In 1978, Mikic [10] evaluated 180 cadaver wrists and demonstrated that TFCC degeneration is directly related to age; statistically, all patients older than 50 have a degenerated TFCC, and many have perforations. Mikic found no TFCC perforations in patients younger than 30. In addition, Viegas and colleagues [11] examined 393 cadaver wrists and found a direct relation between the age of the specimen and the incidence of TFCC tears. In light of these

Dorsal View

Dorsal View

Tfcc Meniscus Homologue

volar (top) and dorsal (bottom) radioulnar ligaments

Fig. 1. Triangular fibrocartilage complex. Dorsal view coronal and axial illustrations of the wrist demonstrate the components of the TFCC. The triangular fibrocartilage proper (asterisks) and volar and dorsal RU ligaments arise from the ulnar border of the sigmoid notch of the radius and insert at the base of the ulnar styloid. The interval between the meniscus homologue, the ulnotriquetral ligament, and the UCL is referred to as the prestyloid recess (curved arrow). D, dorsal; L, lunate; S, scaphoid; T, triquetrum; V, volar.

volar (top) and dorsal (bottom) radioulnar ligaments

Fig. 1. Triangular fibrocartilage complex. Dorsal view coronal and axial illustrations of the wrist demonstrate the components of the TFCC. The triangular fibrocartilage proper (asterisks) and volar and dorsal RU ligaments arise from the ulnar border of the sigmoid notch of the radius and insert at the base of the ulnar styloid. The interval between the meniscus homologue, the ulnotriquetral ligament, and the UCL is referred to as the prestyloid recess (curved arrow). D, dorsal; L, lunate; S, scaphoid; T, triquetrum; V, volar.

findings, TFCC tears must be evaluated in the context of the patient's age, symptoms, and clinical examination to determine whether the TFCC tear is actually the cause of the patient's pain or merely an incidental finding.

In 1988, Palmer [4] devised a classification for lesions of the TFCC, with Type I tears being traumatic and Type II tears degenerative (Table 1).

MRI, conventional arthrography, and MR arthrography are the most useful modalities for imaging the TFCC. Conventional arthrography may be useful in excluding complete tears of the TFCC. However, there can be a connection between the radiocarpal and distal RU joints in 7% to 35% of asymptomatic individuals [12,13]. On MRI, the TFCC is best viewed on coronal images, where it is seen as a low T1, low T2 signal intensity structure extending from the ulnar aspect of the distal radius to the base of the ulnar styloid. When degeneration of the TFC is present, there may be intermediate signal intensity within the TFC on short TE images that does not increase on T2 or T2* images [14]. Degeneration can also appear as thinning of the TFC [3]. When a perforation is present, there may be intermediate signal intensity on T1 and proton-density spin-echo images, which increases on T2-weighted and gradient echo images [15]. In partial tears, the signal abnormality extends

Fig. 2. Traumatic TFCC tears. Coronal fat-suppressed T2-weighted image (A) demonstrates a focal tear at the radial aspect of the triangular fibrocartilage (TFC) (arrow), representing a traumatic tear in this 42-year-old patient who is status post trauma. The patient also has a radial styloid fracture (arrowhead) and a scapholunate ligament tear (asterisk). Coronal fat-suppressed T1-weighted image from an MR arthrogram (B) demonstrates avulsion of the TFC from the sigmoid notch of the radius (arrow), consistent with a Palmer class 1D traumatic tear of the TFC. The patient also has avulsion of the scapholunate ligament, with associated bony avulsion of the scaphoid (arrowhead).

only to one articular surface, whereas in complete tears, the signal abnormality extends to both proximal and distal articular surfaces (Fig. 3) [3]. Fluid signal intensity in the DRUJ may be seen with TFC tears, but this is nonspecific and may also be seen with synovitis or DRUJ irritation [15]. The presence of gadolinium in the DRUJ after MR arthrography increases the specificity. However, as mentioned previously, there can be a communication between the radiocar-pal and distal RU joints in asymptomatic individuals.

Table 1

Palmer classification for triangular fibrocartilage complex lesions

Class 1: Traumatic

1A: Central perforation 1B: Ulnar avulsion with/without distal ulnar fracture

1C: Avulsion from lunate or triquetrum 1D: Avulsion from sigmoid notch of radius

Class 2: Degenerative 2A: TFCC wear

2B: TFCC wear + lunate and/or ulnar chondromalacia 2C: TFCC perforation + lunate and/or ulnar chondromalacia 2D: TFCC perforation + lunate and/or ulnar chondromalacia + LT ligament tear 2E: TFCC perforation + lunate and/or ulnar chondromalacia + LT ligament tear + ulnocarpal arthritis

Abbreviation: LT, lunotriquetral.

Adapted from Palmer AK. Triangular fibrocartilage complex lesion: a classification. J Hand Surg [Am] 1989;14(4):596; with permission.

Tfcc Homologue

Fig. 3. Partial TFCC tear. Coronal T1-weighted (A) and fat-suppressed T2-weighted (B) images demonstrate increased T1, increased T2 signal intensity along the undersurface of the triangular fibrocartilage (arrows) that does not extend to the distal articular surface, consistent with a partial TFCC tear.

Fig. 3. Partial TFCC tear. Coronal T1-weighted (A) and fat-suppressed T2-weighted (B) images demonstrate increased T1, increased T2 signal intensity along the undersurface of the triangular fibrocartilage (arrows) that does not extend to the distal articular surface, consistent with a partial TFCC tear.

Over the past 20 years, several authors have reported wide variation in sensitivity, specificity, and accuracy of MRI compared with arthroscopy. Sensitivity has ranged from 17% to 100%, specificity from 79% to 93%, and accuracy from 64% to 97% [16-21]. The lower numbers reflect studies evaluating the peripheral TFCC. The peripheral TFCC is difficult to evaluate on conventional MRI because of the loose connective tissue in this region, which can appear hy-perintense on T2-weighted images, mimicking a tear. Most recently, Schmitt and colleagues [22] studied 125 patients with MR arthrography and arthroscopic correlation in 2003. They demonstrated a sensitivity of 97.1%, a specificity of 96.4%, and an accuracy of 96.8% for the detection of TFCC lesions. Although more studies of MR arthrography are necessary, MR arthrography may prove to be most useful for evaluating MR problem areas, such as ul-nar-sided TFCC tears (Fig. 4).

LUNOTRIQUETRAL LIGAMENT

The lunotriquetral ligament (LTL) is a true ligament in its dorsal and volar aspects and is membranous in the proximal fibrocartilaginous region [23]. The volar portion is the strongest portion of the LTL [24,25]. The dorsal and volar portions attach directly to bone, whereas the membranous portion attaches to hyaline cartilage [15]. The LTL acts as one of the three major stabilizers of the LT joint, along with the volar radiolunotriquetral ligament and the dorsal radiocarpal ligament [26]. The scaphoid imparts a flexion moment, and the tri-quetrum imparts an extension moment, with a ''balanced lunate'' suspended between them [23,27]. When there is disruption of the ligamentous attachment between the lunate and triquetrum, the lunate becomes unbalanced and flexes with the scaphoid, leading to a volar intercalated segmental instability (VISI) deformity [23].

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Responses

  • BERYLLA FAIRBAIRN
    What is meniscal homologue?
    5 years ago
  • Blake
    Are wrist undersurface tfcc tears surgical?
    4 years ago

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