Imaging assessment of dorsal scaphoid displacement in patients with scapholunate ligament tears: what is the best option for quantitative assessment?

OBJECTIVE: To compare four different methods for the quantitative assessment of dorsal scaphoid displacement in patients with scapholunate ligament tears. METHODS: A total of 160 consecutive patients who underwent CT arthrography to evaluate a suspected scapholunate ligament tear were prospectively included in this study approved by the local ethics committee. MR images were available for 65 of these patients. Two readers independently evaluated the dorsal scaphoid displacement on conventional radiographs with the dorsal tangential line (DTL) method, the posterior radioscaphoid angle (PRSA) on both CT and MR, and the radioscaphoid congruency ratio on MR. These measurements were compared in groups of patients with and without scapholunate ligament tears. RESULTS: The measurement interobserver agreement was considered excellent for the DTL and the PRSA on CT (ICC = 0.93 and 0.88, respectively), good for the PRSA (ICC = 0.65) on MR, and moderate for the RSCR (ICC = 0.49). There was a significant increase in the values of DTL and PRSA on CT between patients with normal and ruptured SLIL (p < 0.0001). The same tendency was seen on MR-based methods, but these differences were only significant for one reader. The only method that allowed the differentiation between patients with normal and partially ruptured SLIL was the PRSA on CT. PRSA on CT yielded the best diagnostic performance for SLIL rupture (a sensitivity and a specificity of 70-82% and 70-72%). CONCLUSION: DTL on standard radiographs and the PRSA on CT are the most consistent imaging indicators of SDD with an excellent interobserver reproducibility. KEY POINTS: • Dorsal scaphoid displacement is an important prognostic factor in patients with scapholunate instability. • Quantitative assessment of dorsal scaphoid displacement can be performed on conventional radiographs and CT with an excellent reproducibility. • The posterior radioscaphoid angle on CT yielded the best diagnostic performance for the identification of scapholunate ligament tears and the only method allowing differentiation between patients with normal and partially torn ligaments.

Four-Dimensional CT Analysis of Dorsal Intercalated Segment Instability in patients with Suspected Scapholunate Instability.

Background In this study we sought to evaluate the contribution of dynamic four-dimensional computed tomography (4DCT) relative to the standard imaging work-up for the identification of the dorsal intercalated segment instability (DISI) in patients with suspected chronic scapholunate instability (SLI). Methods Forty patients (22 men, 18 women; mean age 46.5 ± 13.1 years) with suspected SLI were evaluated prospectively with radiographs, arthrography, and 4DCT. Based on radiographs and CT arthrography, three groups were defined: positive SLI ( n = 16), negative SLI ( n = 19), and questionable SLI ( n = 5). Two independent readers used 4DCT to evaluate the lunocapitate angle (LCA) (mean, max, coefficient of variation [CV], and range values) during radioulnar deviation. Results The interobserver variability of the 4DCT variables was deemed excellent (intraclass correlation coefficient = 0.79 to 0.96). Between the three groups, there was no identifiable difference for the LCA mean . The LCA max values were lower in the positive SLI group (88 degrees) than the negative SLI group (102 degrees). The positive SLI group had significantly lower LCA cv (7% vs. 12%, p = 0.02) and LCA range (18 vs. 27 degrees, p = 0.01) values than the negative SLI group. The difference in all the LCA parameters between the positive SLI group and the questionable SLI group was not statistically significant. When comparing the negative SLI and questionable SLI groups, the LCA cv ( p = 0.03) and LCA range ( p = 0.02) values were also significantly different. The best differentiation between patients with and without SLI was obtained with a LCA cv and LCA range threshold values of 9% (specificity of 63% and sensitivity of 62%) and 20 degrees (specificity of 71% and sensitivity of 63%), respectively. Conclusion In this study, 4DCT appeared as a quantitative and reproducible relevant tool for the evaluation of DISI deformity in cases of SLI, including for patients presenting with questionable initial radiography findings. Level of evidence This is a Level III study.

Evaluation of Dorsal Scaphoid Displacement Using Posterior Radioscaphoid Angle in Patients With Suspected Scapholunate Instability: A Preliminary Study.

PURPOSE: To assess the validity and reliability of the posterior radioscaphoid angle (PRSA), an indicator of dorsal displacement of the scaphoid, in distinguishing wrists with and without chronic scapholunate instability (SLI). METHODS: We prospectively evaluated 40 patients (22 men and 18 women; mean age, 46 ± 13 years) with suspected SLI with radiographs and computed tomography arthrography. Based on these data, 3 groups were defined: positive SLI (n = 16), negative SLI (n = 19), and questionable SLI (n = 5). An independent reader measured the PRSA on sagittal computed tomography images using the same procedure. RESULTS: The PRSA median values were significantly lower in the negative SLI group (98°) compared with the positive SLI (110°) and questionable SLI (111°) groups. The difference between the positive SLI and questionable SLI groups was not significant. The best differentiation between patients with and without SLI was obtained with a PRSA threshold value of 103° (specificity of 86% and sensitivity of 79%). CONCLUSIONS: In this preliminary study, PRSA analysis offers a quantitative tool for the evaluation of dorsal scaphoid displacement in cases of SLI, including for patients presenting with questionable initial radiography findings. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

Assessment of scapholunate instability with dynamic computed tomography.

We performed a prospective study to evaluate the values of dynamic four-dimensional computed tomography in assessing suspected chronic scapholunate instability. Forty patients were evaluated with radiographs, arthrography, and four-dimensional computed tomography. On plain radiographs and computed tomography, we found 16 patients with definite scapholunate instability, five with questionable scapholunate instability, and 19 with absence of scapholunate instability. We used four-dimensional computed tomography to evaluate the size of the scapholunate gap during radioulnar deviation. The mean and maximal values of the gap size were lowest in the patients with absence of scapholunate instability and highest in those with definite scapholunate instability. When comparing the scapholunate gap sizes of the patients with absent and questionable scapholunate instability, the range of the gap sizes was significantly higher in the patients with questionable scapholunate instability. We conclude that four-dimensional computed tomography aids assessment of chronic scapholunate instability, which allows the differentiation between patients without and those with definite or questionable scapholunate instability. Level of evidence: II.