Understanding carpal instability: a radiographic perspective

Evaluating inter- and intraobserver reliability in radiographic determination of wrist alignment following scaphoid excision and four-corner arthrodesis

Background

Four-corner arthrodesis is commonly performed for advanced collapse patterns of wrist arthritis. Reduction of the capitolunate (CL) angle during four-corner fusion is crucial to allow for the greatest radiocarpal joint arc of motion. Previous studies demonstrate variable inter- and intraobserver reliability of measuring the CL angle. However, in a four-corner fusion, hardware implementation and scaphoid excision can complicate carpal alignment measurements. The purpose of this study is to investigate inter- and intraobserver reliability of measuring carpal alignment parameters following scaphoid excision and four-corner arthrodesis.

Methods

Three fellowship-trained orthopaedic hand surgeons evaluated 30 posteroanterior and lateral radiographs of wrists after scaphoid excision and four-corner fusion. Radiographic evaluation included analysis of the radiolunate angle (RL), CL angle, lunate posture, carpal height, carpal height ratio, hardware impingement, and arthrodesis technique. Intraclass correlation coefficients (ICCs) and kappa values were used to evaluate reliability of radiographic measurements.

Results

RL and CL angles demonstrated very good inter- (ICCs: 0.657 and 0.693, respectively) and intraobserver agreement (ICCs: 0.576 to 0.924 and 0.596 to 0.811, respectively). Hardware impingement metrics by dorsal prominence and radiocarpal prominence had excellent interobserver reliability of 0.821 and 0.803, respectively. ICC values for arthrodesis technique were equal to 1.00. The inter- and intraobserver ICC values for the number of screws/staples used were in excellent agreement ranging from 0.910 to 1.000.

Conclusions

Our study demonstrated favorable intra- and interobserver reliability at assessing carpal alignment following scaphoid excision and four-corner arthrodesis and these metrics potentially could be used in future research to evaluate long-term surgical outcomes.

Level of evidence

Level III, retrospective cohort study.

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.

Extended and weightbearing wrist 3-T MRI using a novel harness and flexible 24-channel glove coil to evaluate carpal kinematics: a pilot study in 10 volunteers

BACKGROUND

Wrist pain in the extended or extended weightbearing positions may be incompletely evaluated using standard magnetic resonance imaging (MRI) with standard rigid clamshell coils in the neutral position.

PURPOSE

To evaluate a flexible 24-channel glove coil and harness when imaging the wrist in neutral, dorsally extended, and weightbearing positions.

MATERIAL AND METHODS

Ten wrists in 10 asymptomatic volunteers (mean age = 29 years) were scanned. Participants underwent 3-T MRI using the harness and flexible glove coil, acquiring sagittal turbo spin echo (TSE) and half-Fourier acquisition single-shot turbo spin echo (HASTE) pulse sequences. Static TSE images were obtained in neutral, extended, and weightbearing positions using proton density parameters and independently evaluated by two radiologists for: dorsal radiocarpal ligament thickness; radiocapitate, radiolunate, and capitatolunate angles; palmar translation of the lunate on the radius; angulation of the extensor tendons; and distance from the distal extensor retinaculum to Lister's tubercle. Cine HASTE images were dynamically acquired between neutral-maximum extension to measure the radiocapitate angle.

RESULTS

Good reader agreement was observed (r > 0.73) for all measurements except palmar translation in the neutral position (r = 0.27). Significant increases in dorsal radiocarpal ligament thickness; radiocapitate, radiolunate and capitolunate angulation; and extensor tendon angulation were observed between the neutral and extended positions (P < 0.001). A further significant increase in these metrics between extended and weightbearing positions was also seen (P < 0.01).

CONCLUSION

Significant increases in dorsal radiocarpal ligament thickness, articular and tendon angulations occur during wrist extension, that further increase with dorsal weightbearing.

Wrist angle measurements in predicting the presence of a displaced scaphoid fracture

PURPOSE

Early diagnosis and treatment of scaphoid fractures is critical to achieve union and prevent wrist degenerative arthritis. Plain radiographic measurements can guide the early approach to suspected fractures. Specifically, the ability to predict fracture or fracture stability from plain radiographs may allow the traumatologist to expand initial referral to three-dimensional imaging. We evaluated the ability of four measured angles to predict presence of a scaphoid fracture and stability.

METHODS

Fifty patients with a scaphoid fracture and 50 patients without fracture were evaluated for the cortical ring sign, scapho-lunate gapping, lateral scapholunate (SL), radio-scaphoid (RS), radio-lunate (RL), and radio-capitate (RC) angles by two-blinded observers.

RESULTS

Measurement of an increased SL interval was associated with the presence of a scaphoid fracture as diagnosed on three-dimensional imaging [odds ratio (OR) 3.0, confidence interval (CI) 1.53-5.87, p =  < 0.01]. The measured RL angle was associated with fracture displacement (OR 1.13, 95% CI 1.02-1.25, p = 0.02).

CONCLUSIONS

Scapholunate gapping on plain radiographs in the context of a clinically suspected scaphoid fracture should increase suspicion for a fracture and may prompt earlier 3-dimensional imaging, while the presence of an abnormal radiolunate angle should increase wariness for instability and can be used in preoperative planning.

Bilateral Ulnar Deviation Supination Stress Test to Assess Dynamic Scapholunate Instability

PURPOSE

We describe a new radiologic test to assess the integrity of the scapholunate ligament in dynamic scapholunate dysfunction.

METHODS

A bilateral forearm-holding device was designed to perform a comparative radiographic assessment of the scapholunate joint gap during resisted isometric contraction of the extensor carpi ulnaris muscle with full supination of the forearm. The concept is based on the known scaphoid pronation effect of this muscle. Clinical data from 12 patients were collected retrospectively and used to analyze the patients' symptomatic and asymptomatic (contralateral) wrists with a newly developed test called the Bilateral Ulnar Deviation Supination (BUDS) test. A wrist arthroscopy was performed in all cases as a reference standard for the radiologic test.

RESULTS

The test was positive in 7 patients, with a mean scapholunate joint gap of 4.8 mm. The mean differences in the scapholunate joint gaps between both wrists were 2.6 mm in BUDS-positive patients and 0.2 mm in BUDS-negative patients. A Geissler stage III or IV scapholunate ligament rupture was confirmed in all BUDS-positive patients; by contrast, BUDS-negative patients exhibited either no lesion or a Geissler stage I injury.

CONCLUSIONS

The BUDS test is a new radiologic test based on proven biomechanical effects that is able to accurately assess dynamic scapholunate dysfunctions. The analysis carried out found a correlation between radiographic and arthroscopic findings. Further research is needed to confirm the validity and reliability of the test.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Twenty-four-channel high-impedance glove array for hand and wrist MRI at 3T

PURPOSE

To present a novel 3T 24-channel glove array that enables hand and wrist imaging in varying postures.

METHODS

The glove array consists of an inner glove holding the electronics and an outer glove protecting the components. The inner glove consists of four main structures: palm, fingers, wrist, and a flap that rolls over on top. Each structure was constructed out of three layers: a layer of electrostatic discharge flame-resistant fabric, a layer of scuba neoprene, and a layer of mesh fabric. Lightweight and flexible high impedance coil (HIC) elements were inserted into dedicated tubes sewn into the fabric. Coil elements were deliberately shortened to minimize the matching interface. Siemens Tim 4G technology was used to connect all 24 HIC elements to the scanner with only one plug.

RESULTS

The 24-channel glove array allows large motion of both wrist and hand while maintaining the SNR needed for high-resolution imaging.

CONCLUSION

In this work, a purpose-built 3T glove array that embeds 24 HIC elements is demonstrated for both hand and wrist imaging. The 24-channel glove array allows a great range of motion of both the wrist and hand while maintaining a high SNR and providing good theoretical acceleration performance, thus enabling hand and wrist imaging at different postures to extract kinematic information.

Wrist and Hand Trauma Imaging

Injuries to the wrist and hands occur frequently in athletes from the high forces applied during sporting events. The examples presented illustrate the important role imaging has in the diagnosis of wrist and hand injuries. In addition, different imaging modalities are complementary and various examinations may be needed to help guide the management of wrist and hand traumatic pathology.

Dual-energy CT collagen density mapping of wrist ligaments reveals tissue remodeling in CPPD patients: first results from a clinical cohort

OBJECTIVES

To evaluate differences in collagen density as detected by dual-energy computed tomography (DECT) of wrist ligaments between patients with calcium pyrophosphate-dihydrate deposition disease (CPPD) and a control group in order to gain insight into changes of the extracellular matrix in response to crystal deposition.

MATERIALS AND METHODS

This retrospective study included 28 patients (18 with CPPD, 10 controls) who underwent DECT of the wrist. Collagen density maps were reconstructed from the DECT datasets and used to measure densities in regions of interest (ROIs) placed in the scapholunate (SL) ligament (dorsal, palmar, proximal), lunotriquetral (LT) ligament, and extensor carpi radialis (ECR) tendon, (n = 260 measurements). The presence of calcifications on standard CT images in these regions was assessed by a blinded reader. Densities were compared with nonparametric tests, and linear regression analysis was performed to investigate the impact of age, sex, and CT- detected calcium deposition on collagen density.

RESULTS

Collagen density in the SL ligament was significantly higher in CPPD patients than in controls (overall mean: 265.4 ± 32.1 HU vs. 196.3 ± 33.8 HU; p < 0.001). In the ECR tendon, collagen densities did not differ significantly (p = 0.672): 161.3 ± 20.1 HU in CPPD vs. 163.6 ± 12.0 HU in controls. Regression analysis showed that diagnosis, but not age or calcification, had a significant impact on collagen density.

CONCLUSION

Collagen density of the SL ligament is significantly higher in CPPD patients than in control patients. Further research is needed to understand these changes in the extracellular matrix of ligaments in CPPD.

Imaging of Carpal Instabilities

Background The term “carpal instability” describes different debilitating wrist conditions, in which the carpus is unable to maintain its physiological range of motion and load transfer. Depending on the cause and location of the dysfunction, four groups can be defined: dissociative, non-dissociative, complex, and adaptive carpal instability. As the most common form by far, dissociative carpal instability can further be categorized as dorsal or palmar intercalated segment instability, contingent on the afflicted interosseous ligament.

Method This review article outlines the different entities of carpal instability, their pathophysiology, and their clinical presentation. It further discusses the diagnostic significance of different imaging methods as well as the established treatment options for each form of instability in context with the current literature.

Results and Conclusion Early detection and treatment of carpal instability are essential for preventing carpal osteoarthritis. Traumatic lesions of the scapholunate interosseous ligament are the most frequent cause of instability. They can occur in an isolated fashion or in context with other carpal injuries. While stress imaging and fluoroscopy facilitate the differentiation between dynamic and static forms of carpal instability, only MRI and CT/MR arthrography can directly reveal the extent of ligament discontinuity.

Key Points:

Citation Format

Four-dimensional CT Analysis of Wrist Kinematics during Radioulnar Deviation

Purpose To determine the technical feasibility of four-dimensional (4D) CT for analysis of the variation of radioscaphoid angle (RSA) and lunocapitate angle (LCA) during wrist radioulnar deviation. Materials and Methods In this prospective study, 37 participants suspected of having scapholunate instability were evaluated from January 2015 to December 2016 with 4D CT and CT arthrography (mean age ± standard deviation, 42.3 years ± 15; range, 21-75 years; 27 men [mean age, 44 years ± 15] and 10 women [mean age, 38 years ± 14]). Five angular parameters for RSA and LCA variation during radioulnar deviation were calculated by two independent readers. CT arthrography was used as the reference standard method for scapholunate ligament tear identification. Results In the control group (n = 23), the mean values for RSA were 103° ± 8 and 104° ± 9, whereas the mean values for LCA were 86° ± 9° and 90° ± 11° with a coefficient of variation of 11% and 13% for reader 1 and reader 2, respectively. The interobserver and intraobserver agreements were excellent for RSA and substantial to excellent for LCA. In the pathologic group (n = 14), LCA amplitude, standard deviation, and maximal angle were lower for both readers with respect to the control group, measuring 36% and 44% (P = .003), 37% and 44% (P = .002), and 13% and 19% (P = .003), respectively. RSA amplitude did not show statistically significant results in the pathologic group (P > .13). LCA yielded the highest sensitivity (71%-93%), whereas RSA yielded the highest specificity (87%-100%). Conclusion Semiautomatic four-dimensional CT analysis of the wrist during radioulnar deviation is technically feasible and reproducible for evaluation of carpal kinematic abnormalities. © RSNA, 2018 Online supplemental material is available for this article .

Comparison of outcomes between axial radial and axial ulnar carpal injuries

Axial carpal injuries are rare entities where a traumatic force transmits through the intermetacarpal space, dissociating the carpometacarpal joint and disrupting the distal carpal row in an axial radial or axial ulnar pattern via true axial force or compressive crush mechanism. Differences in outcomes remain unclear with regard to the specific type of axial carpal injury pattern. A retrospective case series identified 37 wrists (in 37 patients) over 25 years who presented to a Level 1 trauma centre, with 20 wrists experiencing an axial radial injury and 17 wrists experiencing an axial ulnar injury. Of all the variables evaluated, only axial radial injuries were identified as predictors of poor outcome as defined by Mayo Wrist scores with univariate analysis demonstrating 6 times increased risk and multivariate analysis demonstrating 15 times increased risk of a poor outcome compared with axial ulnar injuries. This knowledge will provide prognostic information to surgeons managing patients with these severe injuries.

LEVEL OF EVIDENCE

IV.

Update on operative treatment of scapholunate (SL) instability for radiologists: part 1-SL ligament repair, dorsal capsulodesis and SL ligament reconstruction

Scapholunate instability is the most common form of carpal instability. Imaging (especially radiography) plays an important role in the staging, management and post-operative follow-up of scapholunate (SL) instability. The goals of this article are to review the pre-operative staging of SL instability, the surgical options for repair and reconstruction of the SL ligament, along with the normal postoperative imaging findings as well as complications associated with these surgical options.

[Ligament injuries of the wrist]

The distal radioulnar joint, the triangular fibrocartilage complex (TFCC) and the wrist are stabilized by many ligaments allowing not only a wide range of motion but also providing sufficient stability. The complex arrangement of carpal ligaments and prosupination around the forearm joint enables multiaxial motion patterns. In the wrist, intra-articular ligaments can be differentiated from extra-articular capsular ligaments as well as intrinsic and extrinsic ligament courses. Imaging is essential for classification of dynamic and static instability patterns. This review article illustrates the ligamentous anatomy of the wrist, the symptoms of carpal instability as well as the diagnostic capability of projection radiography, cinematography, computed tomography (CT) arthrography, magnetic resonance imaging (MRI) and MR arthrography.

Hamate and pisiform coalition: a case report and introduction to the carpal C-sign on lateral radiograph

Hamate-pisiform coalition is an exceptional form of carpal coalition. Case reports are essential to gain a better understanding of this variant. We report a case of congenital bilateral hamate-pisiform coalition in a 20-year-old male discovered in the context of a right wrist trauma. Radiographs also revealed a bilateral scapholunate diastasis. Clinical examination and radiological findings suggested that the right wrist scapholunate diastasis was related to scapholunate instability. Left wrist scapholunate diastasis could be related to (1) a pathological feature or (2) a normal variant associated with hamate-pisiform coalition. Lateral radiographs showed a volar C-shaped osseous bridge corresponding to the coalition. We associated it with a new sign: the "carpal C-sign". Computed tomography with three-dimensional reconstruction provides helpful information about the type of coalition (osseous versus non-osseous) and excludes potential fracture. We discuss the specific embryologic features of the hamate-pisiform coalition, as well as its prevalence, radiographic classification, clinical significance, and treatment.