Quantitative analysis of scapholunate diastasis using stress speckle-tracking sonography: a proof-of-concept and feasibility 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.

Feasibility of ultrasound-based measurement of dorsal scaphoid displacement: A 3D-model study

The present study aimed to develop a reliable dynamic measurement technique, which can be used directly in the outpatient setting, based on dorsal subluxation of the scaphoid on scaphoid shift test. This study was designed to evaluate feasibility and to quantify dorsal subluxation of the scaphoid in relation to the lunate. Based on a scaphoid shift test under ultrasonography, a standardized 3D test model was developed to measure subluxation. Sagittal subluxation ranged between 0 and 6 mm, as checked on the implemented scale. Four hand surgeons trained in ultrasonography (experience level II-V) performed blinded measurements (total of 52, n = 13 per investigator) with a standardized measurement protocol. Dorsal subluxation of the scaphoid was measured in relation to the lunate. Interobserver reliability on intraclass correlation coefficient (ICC) was excellent, at 0.97 (95% confidence interval, 0.930-0.992). Mean overall absolute measurement error was 0.27 mm ± 0.21. Dorsal subluxation of the scaphoid can thus be accurately measured on ultrasound with excellent interobserver reliability, quantifying and improving clinical assessment of scapholunate instability.

Dynamic MRI of the wrist in less than 20 seconds: normal midcarpal motion and reader reliability

OBJECTIVE

To describe the normal motion pattern at the midcarpal compartment during active radial-ulnar deviation of the wrist using dynamic MRI, and to determine the observer performance for measurements obtained in asymptomatic volunteers.

METHODS

Dynamic MRI of 35 wrists in 19 asymptomatic volunteers (age mean 30.4 years, SD 8.6) was performed during active radial-ulnar deviation using a fast gradient-echo pulse sequence with 315 ms temporal resolution (acquisition time, 19 s). Two independent readers measured the transverse translation of the trapezium at the scaphotrapezium joint (STJ) and the capitate-to-triquetrum distance (CTD). Relationships between these measurements and laterality, sex, lunate type, and wrist kinematic pattern were evaluated.

RESULTS

At the STJ, the trapezium moved most in radial deviation, with an overall translation of 2.3 mm between ulnar and radial deviation. Mean CTD measurements were the greatest in ulnar deviation and varied 2.4 mm between ulnar and radial deviation. Mean CTD was greater in men than women in the neutral position (p = 0.019), and in wrists with type II lunate morphology during radial and ulnar deviation (p = 0.001, p = 0.014). There were no significant differences in trapezium translation or CTD with wrist laterality and kinematic pattern. Intraobserver and interobserver correlation coefficients were 0.97 and 0.87 for trapezium translation and 0.84 and 0.67 for CTD.

CONCLUSION

This study is the first to demonstrate the performance of dynamic MRI to quantify STJ motion and CTD. Dynamic MRI with a short acquisition time may be used as a tool to supplement static MRI in evaluation of the midcarpal compartment.

Scapholunate instability: improved detection with semi-automated kinematic CT analysis during stress maneuvers

OBJECTIVES

To evaluate the diagnostic performance of radioulnar deviation (RUD) and clenching fist (CF) maneuvers for the evaluation of scapholunate dissociation (SLD) using quantitative kinematic CT.

METHODS

Thirty-seven patients with suspected scapholunate instability were prospectively evaluated with kinematic CT. Two radiologists independently evaluated the SLD during RUD and CF maneuvers. Various dynamic parameters describing SLD were compared (maximal value, variation coefficient and range) in patients with and without scapholunate ligament ruptures confirmed by CT arthrography.

RESULTS

SLD in CF varied from 3.17 ± 0.38 to 3.24 ± 0.80 mm in controls and from 4.11 ± 0.77 and 4.01 ± 0.85 mm in patients with scapholunate ligament ruptures for reader 1 and 2 (p < 0.009). SLD in RUD varied from 3.35 ± 0.51 and 3.01 ± 0.78 mm in controls and from 4.51 ± 1.26 to 4.42 ± 1.75 mm in patients with scapholunate ligament ruptures for reader 1 and 2 (p varied from 0.001 to 0.002). The inter-observer variability was better for RUD (ICC = 0.85 versus 0.6 for RUD and CF respectively).

CONCLUSION

Analysis of SLD using kinematic CT has shown significant measurement differences between the groups with or without scapholunate instability with good diagnostic performance.

KEY POINTS

• Kinematic CT can quantitatively assess scapholunate dissociation. • SLD analysis on kinematic CT has excellent reproducibility with radioulnar deviation maneuver. • Scapholunate dissociation was significantly different in patients with and without instability. • Diagnostic performance for scapholunate instability identification was better with radioulnar deviation.