Ulnar impaction syndrome: MR imaging findings

High-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T: Comparison of surface coil and volume coil

PURPOSE

To evaluate high-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T using a surface coil (SC) or volume coil (VC).

MATERIALS AND METHODS

MRI was obtained from nine volunteers in the supine position with a 3-inch SC and in prone position with a transmit-receiver wrist VC at 3 T. Coronal two-dimensional-gradient echo (2D-GRE) images (TR/TE/FA = 500 msec/15 msec/40 degrees , 1 mm slice-thickness, 60 mm field of view [FOV], 192 x 256 matrix) and coronal 3D-GRE images (TR/TE/FA = 33 msec/15 msec/10 degrees , 0.8 mm slice-thickness, 80 mm FOV, 256 x 256 matrix) were used. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the TFCC and surrounding structures were measured. For qualitative measurement, visualization of TFCC and intercarpal ligaments was graded.

RESULTS

SNR of TFCC, cartilage, and bone marrow on 2D-GRE with SC/VC was as follows: 5.3/5.3 (TFCC), 16.5/14.4 (cartilage), and 3.61/3.96 (bone marrow). 3D-GRE showed similar SNR. Cartilage-TFCC/cartilage-bone marrow CNR were 11.1/12.8 (SC-2D-GRE), 8.8/10.5 (VC-2D-GRE), 14.1/15.5 (SC-3D-GRE), and 11.9/15.0 (VC-3D-GRE). Quantitative values were not significantly different between SC and VC. Visualization of TFCC and intercarpal ligament with SC was superior to that with VC. All structures show higher scores with 3D-GRE imaging compared to 2D-GRE imaging.

CONCLUSION

SC may provide superior qualitative and quantitative results and can be an alternative in case of difficulty in prone position at 3T.

Role of MR imaging in chronic wrist pain

Magnetic resonance (MR) imaging for chronic wrist pain is challenging. Correct assessment of the triangular fibrocartilage, hyaline cartilage, ligaments, and tendons has become mandatory for comprehensive decision making in wrist surgery. The MR technique, potential and limits of MR imaging in patients with chronic wrist pain will be discussed. MR arthrography with injection of gadolinium-containing contrast material into the distal radioulnar joint is suggested for evaluation of the triangular fibrocartilage. The clinically meaningful ulnar-sided peripheral tears are otherwise hard to diagnose. The diagnostic performance of MR imaging for interosseous ligament tears varies considerably. The sensitivity for scapholunate ligament tears is consistently better than for lunotriquetral ligament tears. Gadolinium-enhanced MR imaging is considered to be the best technique for detecting established avascularity of bone, but the assessment of the MR results remains challenging. Most cases of ulnar impaction syndrome have characteristic focal signal intensity changes in the ulnar aspect of the lunate. Avascular necrosis of the lunate (Kienböck's disease) is characterized by signal changes starting in the proximal radial aspect of the lunate. MR imaging is extremely sensitive for occult fractures. Questions arise if occult posttraumatic bone lesions seen on MR images only necessarily require the same treatment as fractures evident on plain films or computed tomography (CT) images. MR imaging and ultrasound are equally effective for detecting occult carpal ganglia. Carpe bossu (carpal boss) is a bony protuberance of a carpometacarpal joint II and III which may be associated with pain.

Imaging of Ulnar-Sided Wrist Pain

Ulnar-sided wrist pain has long been a diagnostic problem, partly because of the complex anatomy and many possible causes of pain in this region. This article discusses anatomy, pathophysiology, and imaging appearance of the more common causes, including tears of the triangular fibrocartilage complex, disorders of the distal radioulnar joint, tears of the lunotriquetral ligament, disorders of the extensor carpi ulnaris tendon, disorders of the pisotriquetral joint, the impingement and impaction syndromes, and ulnar wrist masses. Along with clinical history and physical examination, imaging is important in evaluation of ulnar-sided wrist pain. Conventional radiographs, conventional arthrography, CT, MRI, and MR arthrography are useful modalities that are often used in concert to help guide diagnosis and treatment.

MR Imaging of Ligaments and Triangular Fibrocartilage Complex of the Wrist

Imaging of the wrist with MR imaging can be difficult because of the small size of this joint, its complex anatomy, and its sometimes poorly understood pathologic lesions. A recent study by Hobby and coworkers of 98 patients revealed that MR imaging of the wrist influences clinicians' diagnoses and management plans in most patients. This article summarizes the current diagnostic criteria that can be useful in interpreting abnormalities of the wrist ligaments and triangular fibrocartilage complex (TFCC) of the wrist in this difficult topic in joint MR imaging.

Ulnar impaction syndrome

Although Palmer's classification of TFCC lesions differentiates post-traumatic central perforations (IA tears) from degenerative tears secondary to ulnocarpal impaction (IIC) [3], the distinction is not always clear clinically. In the final analysis, the literature suggests that as many as 25% of wrists with TFCC tears have residual symptoms following arthroscopic debridement alone [23], and it is likely that static or dynamic ul-nar positive variance plays a role [2,5,17,25]. The authors' results suggest that combined arthroscopic TFCC debridement and wafer resection are feasible and efficacious as treatment for all stages of ulnar impaction syndrome. When class II A and B changes are observed, that is, when a TFCC perforation has not yet developed, the authors have observed favorable results in most patients following arthroscopic TFCC central disc excision and wafer resection as an alternative to ulnar shortening osteotomy [33] or open wafer excision [10].

Results of ulnar shortening osteotomy for ulnocarpal impaction syndrome in wrists with neutral or negative ulnar variance

Ulnocarpal impaction syndrome was diagnosed in six wrists of five patients with neutral or negative ulnar variance. All underwent ulnar shortening with satisfactory results. The average grip strength increased from 53% to 78% and the range of flexion-extension increased from 82% to 93%, the mean Cooney's score improved from 25 to 83. These cases show that ulnocarpal impaction syndrome can occur in wrists with zero or negative ulnar variance, and that ulnar shortening is an effective treatment for such wrists.

Ulnar shortening osteotomy after Colles fracture

Ulnar shortening is well accepted in the treatment of ulnar abutment but less so in patients with a shortened radius and ulnar-sided wrist pain as a result of a Colles fracture. Sixteen patients with pain and reduced range of movement (ROM) and a median preoperative ulnar positive variance of 5 mm (range 0.5-11) had 17 osteotomies. Nine were male and seven female with a median age of 35 (range 15-55) years were operated on. Fifteen patients with 16 osteotomies could be reached for follow-up. The ulna was shortened by a median of 4.5 mm (range 3-12). The median pain score was reduced by 3 points (range 0-5). Postoperative ROM was improved in nine, unchanged in six, and reduced in one wrists. There were four complications: one re-fracture, two transient paraesthesiae, and one superficial infection. Seven of the patients regarded the result as excellent, six as good, three as fair, and none regarded it as poor. Thirteen of the 16 would have chosen the operation again, three would not.

Ulnocarpal impaction syndrome restricts even midcarpal range of motion

Ulnocarpal impaction syndrome is believed to be caused by abutment between the ulna and the ulnar carpus. We measured radiocarpal and midcarpal ranges of motion in 40 patients with ulnocarpal impaction syndrome by radiographic motion studies. The results showed that the radiocarpal and midcarpal ranges of motion were equally restricted in the affected wrist compared with the unaffected wrist. Therefore, motion of the radiocarpal joint and midcarpal joint contributed equally to total wrist motion bilaterally. No correlation between ulnar variance and the contribution of radiocarpal motion to overall wrist motion was found. Restriction of wrist motion in ulnocarpal impaction syndrome is not caused directly by abutment between the ulna and ulnar carpus, but a satisfactory explanation for restricted motion is still lacking.

Wrist MR Arthrography: How, Why, When

MR imaging of the wrist frequently represents a diagnostic challenge for radiologists because of the complex anatomy of this joint, small size of its components, and little known pathologic conditions. MR arthrography combines the advantages of conventional MR imaging and arthrography by improving the visualization of small intra-articular abnormalities. This article reviews the current role of MR arthrography in the evaluation of wrist joint disorders considering the relevant aspects of anatomy, techniques, and applications.

Lunate Chondromalacia: Evaluation of Routine MRI Sequences

OBJECTIVE

Chondromalacia is a commonly encountered abnormality at arthroscopy and may be responsible for significant clinical symptoms and disability. In the wrist, the most common location for chondromalacia is the lunate bone. Consequently, we sought to study the accuracy of clinical MRI in the assessment of lunate articular cartilage.

MATERIALS AND METHODS

MR images of 34 patients who underwent arthroscopy and had an MRI examination within 1 month of surgery were evaluated by two reviewers for the presence and location of lunate cartilage defects and subchondral edema.

RESULTS

Lunate cartilage defects were seen on MRI in 10 of the 13 patients with chondromalacia, but these defects were also incorrectly noted in three of 21 of patients without chondromalacia. The visible locations for cartilage defects were the ulnar aspect of the proximal lunate bone (n = 3), radial aspect of the proximal lunate bone (n = 4), ulnar aspect of the distal lunate bone (n = 2), and radial aspect of the distal lunate bone (n = 1). Subchondral marrow edema was observed in six of the 10 patients with chondromalacia seen on MRI; in all six patients, the edema was seen in the same quadrant as the cartilage defect. Marrow edema was detected in one patient without chondromalacia.

CONCLUSION

We conclude that lunate chondromalacia can be accurately assessed using routine MRI sequences, although there are occasional false-positive interpretations.

MR imaging of ligaments and triangular fibrocartilage complex of the wrist

Imaging of the wrist with MR imaging can be difficult because of the small size of this joint, its complex anatomy, and its sometimes poorly understood pathologic lesions. A recent study by Hobby and coworkers of 98 patients revealed that MR imaging of the wrist influences clinicians' diagnoses and management plans in most patients. This article summarizes the current diagnostic criteria that can be useful in interpreting abnormalities of the wrist ligaments and triangular fibrocartilage complex (TFCC) of the wrist in this difficult topic in joint MR imaging.

MR imaging findings in ulnar-sided wrist impaction syndromes

Ulnar-sided wrist impaction syndromes are a common source of ulnar pain and limitation of motion. These conditions refer to a group of pathologic entities that result from repetitive or acute forced impaction between the distal ulna and ulnar carpus or distal radius and surrounding soft tissues. MR imaging allows earlier detection of the bone and soft-tissue lesions that are present in the different ulnar-sided wrist impaction syndromes and is helpful in formulating the extensive differential diagnosis in patients with ulnar wrist pain and limitation of motion.

High-resolution MR imaging of triangular fibrocartilage complex (TFCC): comparison of microscopy coils and a conventional small surface coil

OBJECTIVE

To compare MR images of the triangular fibrocartilage complex (TFCC) using microscopy coils with those using a conventional surface coil qualitatively and quantitatively.

DESIGN AND PATIENTS

Proton density-weighted images and T2*-weighted images of the TFCC from ten normal volunteers were obtained with a conventional surface coil (C4 coil; 80 mm in diameter), a 47-mm microscopy surface coil and a 23-mm microscopy surface coil) at 1.5 T. Qualitative image analysis of MR images with three coils was performed by two radiologists who assigned one of five numerical scores (0, nonvisualization; 1, poor; 2, average; 3, good; 4, excellent) for five TFCC components, which were disc proper, triangular ligament, meniscus homologue, ulnotriquetral and ulnolunate ligament. Quantitative analysis included the signal-to-noise ratio (S/N) of the disc proper of TFCC, the lunate cartilage, the lunate bone and the contrast-noise-ratio (C/N) between articular cartilage and disc proper or bone marrow were measured.

RESULTS

All structures show higher scores qualitatively on MR with microscopy coils than those with a C4 coil, and the difference was significant with the exception of the ulnolunate ligament. MR with microscopy coils showed significantly higher S/N values than those with a conventional surface coil (P<0.05 to P<0.001). T2*-weighted images using microscopy coils showed significantly higher cartilage-disc proper C/N and cartilage-bone marrow C/N (P<0.01 to P<0.001). On proton density-weighted images, the C/N between cartilage and disc proper with two microscopy coils was significantly higher (P<0.01) than that with a conventional coil.

CONCLUSION

High-resolution MR images of the normal wrist using microscopy coils were superior to those using a conventional surface coil qualitatively and quantitatively. High-resolution MR imaging with a microscopy coil would be a promising method to diagnose TFCC lesions.

MR imaging of ulnocarpal impaction after fracture of the distal radius

OBJECTIVE

The purpose of our study was to evaluate the incidence of ulnocarpal impaction after distal radius fracture using MR imaging and to correlate imaging findings with those of radiography and clinical findings.

CONCLUSION

Ulnocarpal impaction is a common finding after distal radius fracture. MR imaging can detect characteristic bone marrow changes of the lunate early after the trauma. A significant correlation exists between MR imaging findings and the extent of posttraumatic ulnar variance and pain levels.

Clinically significant skeletal variations of the shoulder and the wrist: role of MR imaging

Several skeletal variations of the upper extremity may cause painful conditions or precipitate early degenerative changes, either spontaneously or in response to overuse and trauma. Magnetic resonance imaging has proved particularly useful for accurate interpretation of many of these clinically significant skeletal variations; however, the widespread use of MR imaging may have contributed to over-emphasizing their clinical importance, which is still controversial in many cases. We review, illustrate, and discuss clinically significant skeletal variations of the upper extremity as seen on MR images, particularly those involving the shoulder and the wrist. In the shoulder region, we evaluate variations of acromial and coracoid processes as well as variations and minor dysplastic deformities of the glenoid fossa. We also review different skeletal variations of the carpal region, including ulnar variance, ulnar styloid, lunate morphology, carpal coalition, and carpal accessory ossicles. The role of MR imaging in assessing the clinical importance of such conditions, whether potential, controversial, or well established, is emphasized in this review.

Imaging findings in ulnar-sided wrist impaction syndromes

Impaction syndromes related to ulnar-sided pain include ulnar impaction syndrome, ulnar impingement syndrome, ulnocarpal impaction syndrome secondary to nonunion of the ulnar styloid process, ulnar styloid impaction syndrome, and hamatolunate impingement syndrome. The most common of these, ulnar impaction syndrome, is a degenerative condition of the ulnar side of the wrist related to excessive load bearing across the ulnar carpus, triangular fibrocartilage (TFC) complex, and ulnar head. In an adequate clinical setting, characteristic osseous findings at radiography include positive ulnar variance in ulnar impaction syndrome, a short ulna in ulnar impingement syndrome, nonunion of the ulnar styloid process in ulnar impaction syndrome secondary to ulnar styloid nonunion, an excessively long ulnar styloid process in ulnar styloid impaction syndrome, and type II lunate bone in hamatolunate impingement syndrome. Nevertheless, confirmation of clinical and conventional radiographic findings with magnetic resonance (MR) imaging is often necessary to exclude other entities with similar clinical manifestations. MR imaging allows earlier detection of an abnormality in the TFC complex, cartilage, or bone marrow of carpal bones and is helpful in formulating the extensive differential diagnosis in patients with ulnar wrist pain and limitation of motion.

Combined arthroscopic TFCC debridement and wafer resection of the distal ulna in wrists with triangular fibrocartilage complex tears and positive ulnar variance

Because a certain percentage of patients with positive ulnar variance experience incomplete pain relief after triangular fibrocartilage complex (TFCC) debridement alone, we prospectively evaluated the feasibility and efficacy of combining arthroscopic TFCC debridement with arthroscopic wafer resection in such wrists as part of the same surgical procedure. We enrolled 12 patients between July 1998 and July 2000 and performed both subjective and objective assessment at follow-up with a minimum of 6 months and an average of 14 months. Seven posttraumatic and 5 degenerative tears were identified. Preoperative ulnar variance with a pronated grip x-ray averaged 2 mm and ranged between 1 and 4 mm. At final review 8 patients experienced complete pain relief and 4 experienced only minimal symptoms. The ulnocarpal stress test failed to elicit pain in any wrist. Nine patients were very satisfied, and 3 were satisfied. Grip strength improved 8 kg (36%). This procedure should be considered in the treatment of ulnar wrist pain when TFCC tears and positive ulnar variance coexist.

The importance of the pronated grip x-ray view in evaluating ulnar variance

Although dynamic increases in ulnar variance may accompany functional activity, radiographic assessment of ulnar variance traditionally has used a neutral rotation x-ray of the wrist that provides an image of the radioulnar length with the wrist unloaded. Such a view may underestimate variance in wrists in which power grip and pronation result in significant proximal migration of the radius. This study investigates the effect of a maximum grip effort in combination with forearm pronation on ulnar variance in 22 patients who presented with ulnar wrist pain. The pronated grip x-ray view resulted in statistically significant increases in ulnar variance. Preoperative ulnar variance should be measured using both neutral rotation and pronated grip x-rays before selecting treatment for causes of ulnar wrist pain that are affected by radioulnar length so that dynamic increases in ulnar variance are considered when operative treatment is necessary.

Ulnar impaction syndrome in the ulnar negative and neutral wrist. Diagnosis and pathoanatomy

Although the ulnar impaction syndrome occurs most commonly in the ulnar positive wrist, it can also occur in wrists with either ulnar negative or neutral variance. Dynamic increases in ulnar variance may accompany forceful grip and pronation, but diagnosis of the ulnar impaction syndrome can be difficult nonetheless. This report further substantiates the occurrence of this problem in wrists with neutral and negative variance, and provides a description of diagnostic findings and pathoanatomy.

Imaging of the hand and wrist

This article reviews many of the most commonly used modalities for imaging the hand and wrist. Particular attention is paid to proper radiographic positioning, with emphasis on the four-view wrist series. Standard wrist measurements are detailed, and wrist arthrography is also discussed. Techniques for cross-sectional imaging, computed tomography, and MR imaging are reviewed, and several examples are presented as to where MR imaging is diagnostically valuable.

Imaging of the hand: degeneration, impingement and overuse

Degenerative and overuse diseases as well as impingement syndromes of the hand are illustrated and discussed in this review article. Osteoarthritis of the interphalangeal joints as described by Heberden and Bouchard is a ubiquitous articular disease often associated with synovitis and erosive joint destruction. Osteoarthritis of the trapeziometacarpal joint is classified into four stages for proper indication of operation. Overuse can result in stenosing tenosynovitis around the wrist and in synovitis with or without impingement of the flexor or extensor tendons of the digitis or ruptures of the annular and cruciform pulleys. Although diagnosis of these entities is usually made by history and clinical investigation, ultrasound and MRI can be helpful tools in imaging of these diseases. Scapholunate advanced collapse (SLAC) and scaphoid nonunion advanced collapse (SNAC) are the characteristic degeneration pattern of the wrist and represent the degeneration mechanisms in scapholunate insufficiency and nonunion of the scaphoid. SLAC wrist is a gradual degeneration classified in three stages and found in posttraumatic scapholunate rupture, calcium pyrophosphate dehydrate deposition disease (CPPD), rheumatoid arthritis, neuropathic diseases, trauma, and beta 2-microglobulin associated amyloid deposition. Ulna impaction syndrome is increasingly recognized as a cause of ulnar sided pain and exhibits a characteristic MRI appearance.