Scapholunate ligamentous communicating defects in symptomatic and asymptomatic wrists: characteristics

Detection of scapholunate interosseous ligament injury using dynamic computed tomography-derived arthrokinematics: A prospective clinical trial

Scapholunate interosseous ligament injuries are a major cause of wrist instability and can be difficult to diagnose radiographically. To improve early diagnosis of scapholunate ligament injuries, we compared injury detection between bilateral routine clinical radiographs, static CT, and dynamic four-dimensional CT (4DCT) during wrist flexion-extension and radioulnar deviation. Participants with unilateral scapholunate ligament injuries were recruited to a prospective clinical trial investigating the diagnostic utility of 4DCT imaging for ligamentous wrist injury. Twenty-one participants underwent arthroscopic surgery to confirm scapholunate ligament injury. Arthrokinematics, defined as distributions of interosseous proximities across radioscaphoid and scapholunate articular surfaces at different positions within the motion cycle, were used as CT-derived biomarkers. Preoperative radiographs, static CT, and extrema of 4DCT were compared between uninjured and injured wrists using Wilcoxon signed rank or Kolmogorov-Smirnov tests. Median interosseous proximities at the scapholunate interval were significantly greater in the injured versus the uninjured wrists at static-neutral and maximum flexion, extension, radial deviation, and ulnar deviation. Mean cumulative distribution functions at the radioscaphoid joint were not significantly different between wrists but were significantly shifted at the scapholunate interval towards increased interosseous proximities in injured versus uninjured wrists in all positions. Median and cumulative distribution scapholunate proximities from static-neutral and 4DCT-derived extrema reflect injury status.

Immunohistochemical Investigation of Mechanoreceptors Within the Injured Scapholunate Ligament

PURPOSE

Scapholunate ligaments (SLLs) play a well-established role in maintaining carpal alignment and kinematics, and are innervated with sensory mechanoreceptors located within the ligaments. They are involved in the afferent arc of dynamic wrist stability. The aim of this study was to describe the changes in these mechanoreceptor populations in injured SLLs.

METHODS

Injured SLLs were collected from human wrists at the time of SLL reconstruction or limited wrist fusion, where the ligament remnants would otherwise be discarded. These specimens were formalin-fixed and paraffin-embedded for immunohistochemical analysis to identify mechanoreceptors, which were then classified by type and location within the ligament.

RESULTS

A total of 15 ligaments were collected, with the interval from injury ranging from 39 days-20 years. Eleven ligaments were collected less than one year after injury, and four ligaments were collected two years or more after injury. A total of 66 mechanoreceptors were identified, with 50 mechanoreceptors identified in nine of the 11 specimens collected less than one year after injury. In this group, 54% of the mechanoreceptors resided in the volar subunit, 20% in the dorsal subunit, and 26% in the proximal subunit. Two of the four specimens collected two years or later after injury contained mechanoreceptors, all of which were located in the dorsal subunit. Increasing time from injury demonstrated a decline in mechanoreceptor numbers within the volar subunit.

CONCLUSIONS

Mechanoreceptors were consistently located in the SLL, particularly in the volar subunit of specimens collected less than one year after injury.

CLINICAL RELEVANCE

Ligament reconstruction techniques aim to primarily reconstitute the biomechanical function of the disrupted SLL; however, re-establishing the afferent proprioceptive capacity of the SLL may be a secondary objective. This suggests the need to consider the reconstruction of its volar subunit particularly in those managed within one year of injury.

Assessment of Scapholunate Instability on 4D CT Scans in Patients with Inconclusive Conventional Images

Background Initial imaging work-up using radiography and CT arthrography sometimes can be insufficient to identify a scapholunate (SL) instability (SLI) in patients suspected of having SL ligament tears. Purpose To determine the diagnostic performance of four-dimensional (4D) CT in the identification of SLI and apply the findings to patients suspected of having SLI and with inconclusive findings on radiographs and CT arthrograms. Materials and Methods This prospective single-center study enrolled participants suspected of having SLI (recent trauma, dorsal pain, positive Watson test results, decreased grip strength) between March 2015 and March 2020. Participants with wrist fractures, substantial joint stiffness, or history of wrist surgery were excluded. Each participant underwent radiography, CT arthrography, and 4D CT on the same day. Participants were divided into three groups: those with no SLI, those with SLI, and those with inconclusive results. SL gap and radioscaphoid and lunocapitate angle were measured using semiautomatic quantitative analysis of 4D CT images by two independent readers. Receiver operating characteristic curves were used to evaluate the diagnostic performance of 4D CT. Thresholds were determined with the Youden index and were applied to the inconclusive group. Results Of the 150 included participants (mean age, 41 years ± 14 [SD]; 102 male, 48 female), there were 63 with no SLI, 48 with SLI, and 39 with inconclusive results. The maximum value and range of SL gap measurements on 4D CT scans showed high sensitivity (83% [40 of 48] and 90% [43 of 48], respectively) and high specificity (95% [59 of 62] and 81% [50 of 62], respectively) in the identification of SLI. At least one of these parameters was abnormal on 4D CT scans in 17 of 39 (44%) participants in the inconclusive group, and 10 of 17 (59%) participants had confirmed SLI. In the 22 participants in the inconclusive group with no indication of SLI at 4D CT, follow-up showed no evidence of SLI in 10 (45%) and enabled confirmation of SLI via arthroscopy in three (14%). Conclusion Scapholunate gap measurements on kinematic 4D CT scans enabled correct identification of SLI in 59% of participants with inconclusive results on conventional images. ClinicalTrials.gov registration no. NCT02401568 © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Demehri and Ibad in this issue.

Carpal Instability: II. Imaging

Beyond clinical examination, the various forms of carpal instability are assessed with radiologic methods and arthroscopy. For this purpose, the imaging demand for spatial and contrast resolution is particularly high because of the small ligamentous structures involved. The entities of carpal instability are classified into degrees of severity. Early (dynamic) forms of instability can either be indirectly detected with X-ray stress views and cineradiography or by direct visualization of ruptured ligaments in high-resolution magnetic resonance (MR) imaging and MR or computed tomography (CT) arthrography, with the latter the standard of reference in imaging. Advanced (static) forms of carpal instability are sufficiently well detected on radiographs; visualization of early carpal osteoarthritis is superior on CT. To prevent disability of the hand, the radiologist has to provide an early and precise diagnosis. This case-based review highlights the imaging procedures suitable for detection and classification of carpal instability.

Multimodality Pitfalls of Wrist Imaging With a Focus on Magnetic Resonance Imaging: What the Radiologist Needs to Know

Numerous pitfalls are frequently encountered at multimodality imaging of the wrist, which may mimic various tendinous, osseous, capsuloligamentous, muscular, and neurovascular pathologic conditions. These pitfalls may be secondary to variant anatomy, artifactual due to magnetic resonance imaging or sonographic technique, or represent varying ranges of structure-specific normal including a spectrum of findings associated with aging in asymptomatic subjects. When an imaging finding of questionable significance is encountered, it is critical that the interpreting radiologist make every attempt to review any relevant clinical information in an effort to determine whether the imaging findings in question may account for the patient's presenting symptomology. In order to accurately diagnose true pathology at wrist imaging, it is imperative that the radiologist be familiar with the pitfalls discussed throughout this manuscript that may mimic disease. This familiarity will allow the radiologist to provide a more useful report for referring providers focusing on true pathology while eliminating potentially confusing or misleading findings which are inconsistent with the patient's clinical presentation.

The importance of radial multiplanar reconstructions for assessment of triangular fibrocartilage complex injury in CT arthrography of the wrist

Background

Triangular fibrocartilage complex (TFCC) lesions commonly cause ulnar-sided wrist pain and instability of the distal radioulnar joint. Due to its triangular shape, discontinuity of the TFCC is oftentimes difficult to visualize in radiological standard planes. Radial multiplanar reconstructions (MPR) may have the potential to simplify diagnosis in CT wrist arthrography. The objective of this study was to assess diagnostic advantages provided by radial MPR over standard planes for TFCC lesions in CT arthrography.

Methods

One hundred six patients (49 women, 57 men; mean age 44.2 ± 15.8 years) underwent CT imaging after wrist arthrography. Two radiologists (R1, R2) retrospectively analyzed three randomized datasets for each CT arthrography. One set contained axial, coronal and sagittal planes (MPR_Standard), while the other two included an additional radial reconstruction with the rotating center either atop the ulnar styloid (MPR_Styloid) or in the ulnar fovea (MPR_Fovea). Readers evaluated TFCC differentiability and condition. Suspected lesions were categorized using Palmer’s and Atzei’s classification and diagnostic confidence was stated on a five-point Likert scale.

Results

Compared to standard planes, differentiability of the superficial and deep TFCC layer was superior in radial reconstructions (R1/R2; MPR_Fovea: p < 0.001; MPR_Styloid: p ≤ 0.007). Palmer and Atzei lesions were present in 86.8% (92/106) and 52.8% (56/106) of patients, respectively. Specificity, sensitivity and accuracy for central Palmer lesions did not differ in radial and standard MPR. For peripheral Atzei lesions, sensitivity (MPR_Standard 78.6%/80.4%, MPR_Styloid 94.6%/94.6%, MPR_Fovea 91.1%/89.3%) and accuracy (MPR_Standard 86.8%/86.8%, MPR_Styloid 96.2%/96.2%, MPR_Fovea 94.3%/93.4%) improved with additional styloid-centered (p = 0.004/0.008) and fovea-centered (p = 0.039/0.125) reconstructions. No substantial difference was observed between both radial MPR (p = 0.688/0.250). Interrater agreement was almost perfect for each dataset (κ_Standard = 0.876, κ_Styloid = 0.894, κ_Fovea = 0.949). Diagnostic confidence increased with addition of either radial MPR (p < 0.001).

Conclusions

Ancillary radial planes improve accuracy and diagnostic confidence for detection of peripheral TFCC lesions in CT arthrography of the wrist.

Surgical Techniques for the Treatment of Acute Carpal Ligament Injuries in the Athlete

The treatment of athletes with carpal ligament injuries provides many challenges. Our initial goals remain to make a timely and accurate diagnosis, provide treatment options, and create an environment for shared decision making. To optimize outcomes and facilitate return to play, early surgical intervention may be warranted. This article reviews common carpal ligament injury patterns in the athlete with a focus on both classic and newer surgical techniques.

Intrinsic ligament and triangular fibrocartilage complex tears of the wrist: comparison of MDCT arthrography, conventional 3-T MRI, and MR arthrography

PURPOSE

This study compares the diagnostic performance of multidetector CT arthrography (CTA), conventional 3-T MR and MR arthrography (MRA) in detecting intrinsic ligament and triangular fibrocartilage complex (TFCC) tears of the wrist.

MATERIALS AND METHODS

Ten cadaveric wrists of five male subjects with an average age 49.6years (range 26-59years) were evaluated using CTA, conventional 3-T MR and MRA. We assessed the presence of scapholunate ligament (SLL), lunotriquetral ligament (LTL), and TFCC tears using a combination of conventional arthrography and arthroscopy as a gold standard. All images were evaluated in consensus by two musculoskeletal radiologists with sensitivity, specificity, and accuracy being calculated.

RESULTS

Sensitivities/specificity/accuracy of CTA, conventional MRI, and MRA were 100%/100%/100%, 66%/86%/80%, 100%/86%/90% for the detection of SLL tear, 100%/80%/90%, 60%/80%/70%, 100%/80%/90% for the detection of LTL tear, and 100%/100%/100%, 100%/86%/90%, 100%/100%/100% for the detection of TFCC tear. Overall CTA had the highest sensitivity, specificity, and accuracy among the three investigations while MRA performed better than conventional MR. CTA also had the highest sensitivity, specificity, and accuracy for identifying which component of the SLL and LTL was torn. Membranous tears of both SLL and LTL were better visualized than dorsal or volar tears on all three imaging modalities.

CONCLUSION

Both CT and MR arthrography have a very high degree of accuracy for diagnosing tears of the SLL, LTL, and TFCC with both being more accurate than conventional MR imaging.

Current perspectives on the advantages of 3-T MR imaging of the wrist

The use of 3-T magnetic resonance (MR) imaging systems with improved coil designs and high-resolution MR imaging sequences allows visualization of the musculoskeletal anatomy in exquisite detail and accurate characterization of abnormalities both in soft tissues and in bone. Current high-field-strength MR systems offer particular advantages for diagnostic imaging of the small joints of the extremities, especially the wrists, where multiple overlapping soft-tissue structures may be visually inseparable at lower field strengths because of limited contrast resolution. Diagnostic accuracy obtained with 3-T MR imaging of the wrist performed with an acquisition protocol that includes three-dimensional and proton density-weighted imaging sequences is nearly commensurate with that obtained with MR arthrography. Abnormalities of the ligaments, tendons, cartilage, nerves, blood vessels, and bone are clearly depicted, allowing accurate characterization of perforations, tears, and fractures, as well as various soft-tissue and intraosseous lesions (eg, ganglion cysts), vascular malformations, aneurysms, and neuropathies.

Wrist MRI Arthrogram v Wrist Arthroscopy: What are we Finding?

The aim of the study was to compare the radiological findings of wrist arthrogram with wrist arthroscopy. This allowed us to establish the accuracy (sensitivity, specificity) of MRI arthrogram as a diagnostic tool. Thirty patients (20 female and 10 male) have undergone both wrist MRI arthrogram and wrist arthroscopy over the last 3 years at a District General Hospital. The mean age at arthrogram was 42.4 years with an average 6.7 month interval between the two procedures.

The MRI arthrogram was reported by a consultant radiologist with an interest in musculoskeletal imaging and the arthroscopies performed by two upper limb surgeons. Patients who underwent both procedures were identified. The arthrogram reports and operation notes were examined for correlation. Three main areas of pathology were consistently examined: TFCC (triangular fibrocartilage complex), scapholunate and lunotriquetral ligament tears. The sensitivity and specificity of arthrogram was calculated for each. Other areas of pathology were also noted.

In the case of TFCC tears MRI arthrogram had 90% sensitivity and 75% specificity. The lunotriquetral ligament examination with this technique was 100% sensitivity and specificity. However for scapholunate ligament tears it only had 91% sensitivity and 88% specificity.

Wrist arthrogram and arthroscopy are both invasive techniques. In cost terms the arthrogram remains cheaper but is superseded by arthroscopy as it is both diagnostic and therapeutic.

MR arthrography of the wrist: controversies and concepts

Magnetic resonance arthrography (MRA) has become the preferred modality for imaging patients with internal derangement of the wrist. However, several aspects of MRA use need to be clarified before a standardized approach to the imaging of internal derangement of the wrist can be developed. The objective of the study is to evaluate the efficiency of different magnetic resonance (MR) sequences in the detection of lesions of the triangular fibrocartilage complex (TFCC) and scapholunate and lunotriquetral ligaments on direct MRA. Thirty-one consecutive direct magnetic resonance arthrographic examinations of the wrist using a wrist surface coil were performed for the assessment of the TFCC and intrinsic ligaments on a 1.5-T MR imaging system (Signa; 16 channel, Excite, GE Healthcare, Milwaukee, WI, USA). All patients had wrist pain, and in six cases, there was associated clinical carpal instability. The presence, location, and extent of TFCC, scapholunate ligament (SLL), and lunotriquetral ligament (LTL) lesions on T1 fat-saturated, multiplanar gradient recalled (MPGR) and short tau inversion recovery (STIR) images were identified, compared, and analyzed. Forty-one lesions of the TFCC, SLL, and LTL were visualized on contrast-sensitive (T1 fat-saturated) images in 23/31 (74.2%) patients. Twenty-one lesions of the TFCC and intrinsic ligaments were visualized on noncontrast-sensitive (MPGR and STIR) images (15 tears of the TFCC and six tears of the SLL and LTL). All of these lesions were seen on T1 fat-saturated images; 48.8% (20/41) lesions seen on T1 fat-saturated images (eight tears of TFCC and 12 tears of SLL and LTT) were not seen on MPGR and/or STIR images. Superior contrast resolution, joint distention, and the flow of contrast facilitate the diagnosis of lesions of the TFCC and intrinsic ligaments on contrast-sensitive sequences making MRA the preferred modality for imaging internal derangements of the wrist. Little agreement exists regarding the value and location of perforations of the intrinsic ligaments given that both traumatic and degenerative perforations may be symptomatic. Noncommunicating defects of the ulnar attachments of the triangular fibrocartilage (TFC), tears of the dorsal segment of the SLL, and defects at the lunate attachment of the SLL have a higher likelihood of being symptomatic and caused by trauma rather than by degenerative perforation. Although no consensus exists, it would appear that most arthrographies should be started with a radiocarpal injection. Injection into the distal radioulnar joint should be added if no communicational defects are visualized following radiocarpal injection in patients with ulnar-sided wrist pain.

[Early radiological diagnostics for scapholunate dissociation (SLD)]

The partial tear of the scapholunate ligament (pre-dynamic stage of SLD) as well as the complete tear (dynamic stage) does not lead to carpal malalignment. However, if the completely ruptured ligament is accompanied by lesions of the extrinsic ligaments, both the scaphoid and the lunate are malaligned already at rest (static stage of SLD). Later, osteoarthritis will develop, beginning in the radioscaphoid compartment, progressing to the midcarpal joint, and ending in a carpal collapse (osteoarthrotic stage of SLD). Dynamic SLD is detectable only in stress views and in cinematography. The high utility of MRI for directly visualizing the injured ligament is emphasized: reparation tissue is focally enhanced at the rupture site by intravenously applied contrast agent; the individual segments of the scapholunate ligament can be visualized in direct MR arthrography, therefore allowing differentiation of partial and complete ligamentous tears.

Axial oblique MR imaging of the intrinsic ligaments of the wrist: initial experience

OBJECTIVE

To evaluate two separate MR sequences acquired in the axial oblique plane, parallel to the long axis of the scapholunate (SL) and lunotriquetral (LT) ligaments, to determine whether the addition of these sequences to the standard MR wrist examination improves visualization of the intrinsic ligaments, and the evaluation of their integrity. To our knowledge, this plane has not been described in the literature previously.

DESIGN AND PATIENTS

In total we evaluated 26 patients with chronic wrist pain or instability, referred for MR imaging following assessment by an orthopedic surgeon or physiatrist. All patients underwent initial conventional tri-compartment wrist arthrography, which served as the reference standard. This was immediately followed by MR arthrography, in the standard coronal and true axial planes, as well as in the axial oblique plane. The SL and LT ligaments were initially assessed for the presence or absence of tear, using the standard coronal and true axial sequences, and subsequently re-evaluated with the addition of the axial oblique planes.

RESULTS

A total of ten intrinsic ligament tears were identified with conventional arthrography: six SL and four LT tears. Five of the six SL tears were identified on the standard sequences. All six were diagnosed with the addition of the oblique sequences. There were three false-positive SL tears identified using standard MR imaging, and two false-positives with the addition of the oblique sequences. No LT tear was identified on standard sequences, whereas all four were confidently seen with the addition of oblique images. No false-positives of the LT ligament were recorded with either standard or axial oblique sequences.

CONCLUSION

The study suggests that the addition of axial oblique MR sequences helps identify tears to the intrinsic ligaments of the wrist, particularly the LT ligament. In addition, the axial oblique images assist in localization of the tear.

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.

Funktionelle Anatomie und Biomechanik des Karpus

The wrist is an exceedingly complex structure composed of several joints and a dedicated ligamentous system. Its functional principles allow a wide range of carpal motion and make the wrist remarkably resistant to external stress forces:The proximal carpal row serves as an intercalated link interposed between the static elements of both the forearm and the distal carpal row. Like a flexible place-holder, the proximal row synchronously adapts to the spatial and temporal requirements of the wrist. There are synergistic movement patterns including simultaneous flexion of the proximal row as the wrist is deviated radially and simultaneous extension during ulnar deviation. Together with pronosupination of the radioulnar joints, the combined radial/ulnar inclination and flexion/extension enable spherical, out-of-plane movements of the hand. Carpal function is best explained by the "model of a ring under tension."This review addresses the anatomy and the biomechanics of the wrist and illustrates systematic image analysis by using carpal lines and angles as well as indices of carpal height.

Association between Extrinsic and Intrinsic Carpal Ligament Injuries at MR Arthrography and Carpal Instability at Radiography: Initial Observations

PURPOSE

To retrospectively compare the presence or absence of carpal instability on radiographs with the findings of magnetic resonance (MR) arthrographic evaluation of intrinsic and extrinsic ligament tears in patients with chronic wrist pain.

MATERIALS AND METHODS

The institutional review board approved this study and did not require informed consent. Signs of carpal instability were assessed on static and dynamic radiographs of the wrist obtained in 72 patients (24 female, 48 male; mean age, 36 years; age range, 14-59 years) with posttraumatic wrist pain. MR arthrography was subsequently performed. Two musculoskeletal radiologists independently analyzed the radiographs and MR images. Each intrinsic and extrinsic ligament was individually evaluated for the presence of a ligament tear. The extent of the tear also was recorded. Interobserver agreement regarding MR arthrographic findings was tested by calculating kappa statistics. Statistical comparison between radiography and MR arthrography was performed by using the Fisher exact test.

RESULTS

Twenty-five triangular fibrocartilage complex, 18 (five partial, 13 complete) scapholunate ligament, and 25 (10 partial, 15 complete) lunotriquetral ligament tears were visualized. Twenty-two (all complete) extrinsic ligament tears were detected: two radial collateral ligament, 10 radioscaphocapitate ligament, and 10 radiolunotriquetral ligament tears. Interobserver agreement regarding intrinsic and extrinsic ligament tear detection at MR arthrography was excellent (kappa = 0.80). Nineteen patients had evidence of carpal instability on radiographs. Fourteen (52%) of 27 patients with at least one complete intrinsic lesion had no sign of carpal instability. On the other hand, the association of scapholunate ligament and/or lunotriquetral ligament and extrinsic ligament tears was significantly correlated (P < .001) with carpal instability at radiography.

CONCLUSION

The presence or absence of carpal instability on radiographs depends on the association between intrinsic and extrinsic ligament tears-even partial ones-rather than on the presence of intrinsic ligament tears alone, even when the tears are complete.

Carpal instability

This review addresses the pathoanatomical basics as well as the clinical and radiological presentation of instability patterns of the wrist. Carpal instability mostly follows an injury; however, other diseases, like CPPD arthropathy, can be associated. Instability occurs either if the carpus is unable to sustain physiologic loads ("dyskinetics") or suffers from abnormal motion of its bones during movement ("dyskinematics"). In the classification of carpal instability, dissociative subcategories (located within proximal carpal row) are differentiated from non-dissociative subcategories (present between the carpal rows) and combined patterns. It is essential to note that the unstable wrist initially does not cause relevant signs in standard radiograms, therefore being "occult" for the radiologic assessment. This paper emphasizes the high utility of kinematographic studies, contrast-enhanced magnetic resonance imaging (MRI) and MR arthrography for detecting these predynamic and dynamic instability stages. Later in the natural history of carpal instability, static malalignment of the wrist and osteoarthritis will develop, both being associated with significant morbidity and disability. To prevent individual and socio-economic implications, the hand surgeon or orthopedist, as well as the radiologist, is challenged for early and precise diagnosis.

[Frequency of acute and chronic scapholunate dissociation in distal radius fractures. Different treatment plans]

BACKGROUND

Early diagnosis and appropriate treatment of acute scapholunate dissociation (SLD) is crucial for obtaining a favorable result in fractures of the distal radius. The aim of this study was to determine the incidence of acute SLD in a prospective study and to differentiate this entity from chronic SLD.

PATIENTS AND METHODS

A total of 120 patients with unilateral distal radius fractures were prospectively evaluated for SLD. Stress radiographs were obtained for all patients on the injured side after fixation of the distal radius fractures. In cases of SLD the unaffected side was examined to rule out chronic, bilateral SLD.

RESULTS

Acute SLD was detected in 13 patients (11%), 11 (9.1%) of whom had stage 3 injury. Chronic SLD with bilateral asymptomatic instability was seen in three patients (2.5%).

CONCLUSION

When treating fractures of the distal radius, acute SLD has to be ruled out and to be discriminated from chronic SLD. While acute SLD requires appropriate treatment, immediate treatment of chronic SLD is not indicated.

Variants, pitfalls and asymptomatic findings in wrist and hand imaging

Anatomic variants of the bones, ligaments, tendons and muscles are frequent findings in imaging of the wrist and hand. Many findings especially changes in the triangular fibrocartilage (TFC) and the interosseous ligaments are asymptomatic, their incidence is increasing with age, and they are frequently found bilaterally. Abnormalities such as increased signal within tendons are common in asymptomatic subjects. They may be explained by normal physiology, anatomical variability, MR artifacts or true abnormalities without clinical importance. Although it is not always possible to differentiate variants and artifacts from clinically relevant findings it is important to know their potential etiology and clinical importance and not to over report them as abnormality requiring additional imaging or treatment.

Interosseous Ligament Tears of the Wrist: Comparison of Multi–Detector Row CT Arthrography and MR Imaging

PURPOSE

To compare the accuracy of multi-detector row computed tomographic (CT) arthrography and magnetic resonance (MR) imaging in depicting tears of dorsal, central, and palmar segments of scapholunate (SL) and lunotriquetral (LT) ligaments in cadavers.

MATERIALS AND METHODS

Cadaver wrists were obtained and used according to institutional guidelines and with informed consent of donors prior to death. Nine cadaver wrists of eight subjects were evaluated. MR images were obtained with a 1.5-T MR unit. Imaging protocol included intermediate-weighted coronal and transverse fast spin-echo and coronal three-dimensional gradient-echo sequences. Multi-detector row CT arthrography was performed after tricompartmental injection of 3-6 mL of contrast material with a concentration of 160 mg per milliliter of iodine. Palmar, dorsal, and central segments of both ligaments were analyzed on transverse and coronal MR images and multiplanar multi-detector row CT reconstructions by two musculoskeletal radiologists working independently. Open inspection of the wrists was the reference standard. Sensitivity, specificity, accuracy, and positive and negative predictive values were calculated from the imaging and gross pathologic readings. Statistical significance was calculated with the McNemar test. Weighted kappa values for interobserver agreement were calculated for both imaging modalities.

RESULTS

All ligament segments could be visualized in all cases with both imaging modalities. CT arthrography was more sensitive (100%) than MR imaging (60%) in detection of palmar segment tears (P = .62); specificity of both imaging modalities was 77%. Sensitivity (CT arthrography, 86%; MR imaging, 79%) and specificity (CT arthrography, 50%; MR imaging, 25%) for detection of the central segment tears were determined. Dorsal segment tears were detected only with CT arthrography, while all tears were missed with MR imaging (P = .02). Interobserver agreement was better for multi-detector row CT arthrography (kappa = 0.37-0.78) than for MR imaging (kappa = -0.33 to -0.10).

CONCLUSION

Performance in depiction of palmar and central segment tears of SL and LT ligaments is almost equal for multi-detector row CT arthrography and MR imaging, with much higher interobserver reliability for CT arthrography. CT arthrography is significantly superior to MR imaging in the detection of dorsal segment tears of SL and LT ligaments.

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.

Second metatarsophalangeal joint arthrography: a cadaveric correlation study

Arthrography of the second metatarsophalangeal joint is an important diagnostic tool to evaluate the integrity of the plantar plate and to aid in the decision process for surgical intervention. A variety of filling patterns have been identified with lesser metatarsophalangeal joint arthrography and their significance with soft-tissue pathology remains to be completely understood. The purpose of this cadaveric study was to evaluate dye patterns in a series of arthrograms of the second metatarsophalangeal joint and to correlate them with identifiable anatomic lesions or structural variants. Thirty-nine cadaveric specimens (including 28 matched pairs) underwent second metatarsophalangeal joint arthrography with a colored radiopaque dye. Arthrographic findings were observed and recorded. Specimens exhibiting dye extravasation outside of the capsular constraints of the joint were dissected to discover any soft-tissue abnormalities. Twenty-one percent of specimens exhibited abnormal extravasation of dye outside of the joint capsule. A plantar plate tear was identified in 2 of these specimens. Filling of the first intermetatarsophalangeal bursa occurred in 6 specimens. However, because this finding was identified in 2 matched pairs, an anatomic variance is suggested rather than a pathologic entity. This cadaveric study shows that anatomic variances exist concerning the second metatarsophalangeal capsule and that arthrography should be correlated with the clinical scenario.

Sonography of the scapholunate ligament in four cadaveric wrists: correlation with MR arthrography and anatomy

OBJECTIVE

The objective of our study was to sonographically characterize the dorsal aspect of the scapholunate ligament in cadaveric wrists using arthrography, MR arthrography, and anatomic correlation as the gold standard.

MATERIALS AND METHODS

The dorsal aspect of the scapholunate ligament in four cadaveric wrists was evaluated on sonography without knowledge of the findings from standard arthrography, MR arthrography, and anatomic sectioning. The sonographic findings were compared with the findings from other modalities. The criteria for an abnormal scapholunate ligament included an abnormal contrast communication between the radiocarpal and midcarpal joints on arthrography and a discontinuity of the dorsal aspect of the scapholunate ligament that was documented both on MR arthrography and at anatomic sectioning.

RESULTS

Arthrography, MR arthrography, and anatomic sectioning showed the dorsal aspect of the scapholunate ligament to be normal in one specimen and abnormal in three specimens. On sonography, the normal scapholunate ligament was hyperechoic between the scaphoid and lunate bones. In the three cases of abnormality, a normal scapholunate ligament was not visualized, and an abnormal hypoechogenicity was present.

CONCLUSION

The dorsal aspect of the scapholunate ligament can be depicted on sonography; abnormality is present in patients in whom the normally hyperechoic fibrillar ligament is hypoechoic or absent.

Magnetic resonance imaging of the wrist ligaments

The advent of small arthroscopes has enabled the hand surgeon to visualize the ligaments of the wrist directly with resultant increased accuracy in diagnosing and treating pathology. Orthopaedists are now demanding a preoperative assessment and this, in turn, has necessitated that radiologists have a comprehensive understanding of wrist anatomy. High resolution MR imaging can identify the wrist ligaments reliably and provide information concerning their integrity. Interpretation is not straightforward; there is considerable anatomic variation, and there are perforations, defects and degenerative tears that can be troublesome in diagnosing injury. However, with experience and attention to anatomic detail, the radiologist can provide useful information regarding structural abnormalities. When injured, the ligaments of the wrist behave as other joint ligaments do. Findings following injury include discontinuity of normal striated bands, incomplete disruption, irregularities and alteration in normal signal. Fluid pooling around a ligament and concomitant bone injury are other clues to injury. The identification of such structural abnormalities may help to explain altered biomechanics and improve the management of patients following wrist injury.