Ultra-high-resolution computed tomography (CT) imaging of the lunate in Kienböck’s disease: a feasibility study and preliminary observations

Introduction

Kienböck’s disease remains a challenging condition in hand surgery, with its etiology and pathogenesis still not fully elucidated. Recently, the wrist-joint tamponade has been proposed as a potential mechanism that may account for both traumatic and non-traumatic cases (1-4). The disease may progress from isolated lunate involvement to lunate collapse accompanied by carpal alignment changes, and eventually to advanced wrist arthritis. Once lunate collapse or fragmentation leads to carpal instability, the prognosis is poor and more aggressive treatment may be required (5). Several classification systems have been proposed, with the Lichtman classification being the most widely used (6-8). This classification depends primarily on plain radiographs in conjunction with magnetic resonance imaging (MRI) to evaluate disease severity and guide treatment. Because the trabecular bone plays a vital role in maintaining mechanical stability within the lunate, direct visualization of microstructural alterations may provide important clues for understanding the pathogenesis and progression of Kienböck’s disease (9,10). However, conventional imaging modalities have limited spatial resolution and therefore cannot depict trabecular microstructural changes.

Destruction of trabecular microstructure in Kienböck’s disease has been thought to compromise the mechanical stability of the lunate, thereby contributing to its collapse (10). Micro-computed tomography (micro-CT) can provide high-resolution, three-dimensional imaging of trabecular bone and is considered the gold standard for assessing trabecular microstructure. Previous micro-CT studies have offered valuable insights into the trabecular changes in Kienböck’s disease (10-12). Nevertheless, its clinical application is restricted by high radiation exposure and narrow scan field, confining its use to in vitro specimens and small animal experiments (9-13).

Recent advances in imaging technology have enabled the clinical application of ultra-high-resolution computed tomography (UHR-CT), which provides spatial resolution up to 100 µm while reducing radiation exposure. This modality allows in vivo assessment of trabecular bone structure (thickness~100–200 µm) and has been used in the field of otolaryngology, particularly for imaging of middle ear ossicles (14-17). However, its application to wrist imaging, especially for evaluating lunate trabeculae in Kienböck’s disease, has not yet been reported.

The present study aimed to evaluate the feasibility of UHR-CT for in vivo imaging of lunate trabeculae in patients with Kienböck’s disease. We further sought to characterize the trabecular changes across different disease stages and explore the potential of UHR-CT for improving diagnosis, classification, and understanding disease progression.

Methods

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional ethics board of Beijing Jishuitan Hospital, and individual consent for this retrospective analysis was waived. Patients diagnosed with Kienböck’s disease who underwent X-ray, UHR-CT, and MRI examinations at Beijing Jishuitan Hospital between 2022 and 2025 were included. The exclusion criteria were: (I) lunate fracture due to high energy trauma; (II) history of wrist surgery; (III) incomplete imaging data; (IV) patients with systemic metabolic bone disease. Ultimately, six patients with Kienböck’s disease were enrolled in this study. In addition, six age- and sex-matched cases with intact lunate undergoing UHR-CT examination served as a reference group.

Imaging acquisition

Standard posteroanterior and lateral radiographs of the wrist were obtained with the shoulder abducted 90 degrees and the elbow flexed 90 degrees. For the posteroanterior view, the forearm was pronated and the wrist was maintained in neutral position (no flexion/extension or radial/ulnar deviation). For the lateral view, the forearm was positioned in neutral rotation with the wrist kept neutral. MRI was performed with a 3.0 T whole body MRI scanner (Achieva, Philips Healthcare) equipped with a wrist coil. UHR-CT imaging was performed using a UHR-CT scanner (Ultra3D, LargeV, Beijing, China). The scanning parameters were as follows: voltage =100–110kVp, current =120–180 mAs, field of view =65×65 mm, and isotropic voxel size =0.1 mm. Each scan comprised 320–370 slices. The effective radiation dose of UHR-CT was approximately 82.99 µSv. The raw data were reconstructed into images with a slice thickness of 0.1 mm.

Image analysis

The radiographic assessment included: the radioscaphoid angle, Ståhl index, and the Nattrass index (18-20). MRI was used to evaluate bone marrow signal changes within the lunate and the status of the articular cartilage. The stage of Kienböck’s disease was determined according to the Lichtman classification based on a combination of radiographic and MRI findings. Staging was independently assessed by two senior physicians and determined by consensus. The UHR-CT images of the lunate were analyzed through both qualitative and quantitative assessments to characterize trabecular microstructure across different disease stages. For qualitative assessment, the following features were evaluated: (I) the regularity and orientation of trabecular alignment; (II) the uniformity of bone density distribution within the lunate; and (III) the presence of microfractures, or cortical discontinuities. For quantitative analysis, the trabecular bone parameters were calculated within a predefined volume of interest (VOI), as described in previous studies (10,13). The following morphological parameters were measured using the BoneJ plugin in ImageJ software: trabecular thickness (Tb.Th, µm), trabecular spacing (Tb.Sp, µm), and bone volume fraction (bone volume/total volume) (BV/TV, %) (21).

Statistical analysis

Because of the limited sample size, patients were grouped according to the status of carpal alignment for exploratory comparison: the normal alignment group (stage I–IIIA) and the malalignment group (stage IIIB–IV). Continuous variables were expressed as mean and standard deviation and categorical data as frequencies or percentages. Conventional hypothesis tests were considered underpowered and therefore not performed. Instead, exploratory effect sizes (Hedges’ g) with 95% confidence intervals (CIs) were calculated to describe the magnitude and direction of group differences. Hedge’s g values of 0.2, 0.5 and 0.8 were interpreted as small, moderate and large effect sizes, respectively (22,23). All analyses were performed using R version 4.3.1 (R Foundation for Statistical Computing, Vienna, Austria).

Results

Patient demographics

The clinical characteristics of the enrolled patients were summarized in Table 1. This study included three males and three females, with a mean age of 25±10.8 years (range, 15–44 years) at the time of diagnosis. All patients had unilateral involvement, with the left side affected in four cases. According to the Lichtman classification, two patients were classified as stage I, one stage IIIA, two stage IIIB, and one stage IIIC. Therefore, the normal alignment group included three patients and malalignment group included three patients. The median symptom duration was 5 months in the malalignment group and 12 months in the normal alignment group. The malalignment group showed a larger radioscaphoid angle (median 62.8°; range, 61.5–70.4°) compared with the normal alignment group (median 40.9°; range, 39.7–46.5°). Conversely, both the Ståhl index (median 0.38; range, 0.31–0.39 vs. median 0.53, range, 0.43–0.65) and the Nattrass index (median 1.39; range, 1.36–1.42 vs. median 1.52, range, 1.45–1.61) were lower in the malalignment group. Values in the reference group were within the reported normal ranges for all three indices and were comparable to those of the normal alignment group.

Qualitative assessment of UHR-CT findings

On UHR-CT, the lunate in the reference group typically showed an intact cortical bone and a well-organized trabecular architecture, with radially oriented trabeculae nearly perpendicular to the radiolunate and capitolunate articular surfaces (Figure 1). In patients with Kienböck’s disease, both groups demonstrated the evidence of trabecular fractures within the affected lunate. In the normal alignment group, fine microfractures or focal trabecular discontinuities were present, and the lunate generally exhibited a uniform bone density distribution with mild regional variation, no consistent anatomical localization pattern was observed in this pilot cohort (Figure 2). In contrast, the malalignment group demonstrated pronounced structural disruption, characterized by fragmented, disorganized trabeculae with markedly irregular orientation. The lunate showed heterogeneous bone density, characterized by coexisting sclerotic regions of high density and cystic or necrotic areas of low density. In addition, degenerative cortical destruction, marginal irregularities, and subchondral bone erosion were visible in the distal radius, scaphoid, triquetrum, and capitate, consistent with early arthritic changes (Figure 3).

Figure 1 A 40-year-old female presented with left wrist pain after trauma and underwent UHR-CT to exclude an occult fracture. Coronal (A), axial (B), and sagittal (C) UHR-CT images revealed an intact lunate with fine, well-organized trabeculae and homogeneous bone density. UHR-CT, ultra-high-resolution computed tomography.

Figure 2 A 15-year-old male complained of mild left wrist pain for three months. He had no history of trauma. Posteroanterior (A) and lateral (B) radiographs of the left wrist showed no apparent abnormalities. Sagittal (C) and coronal (D) T2-weighted MRI images revealed a localized area of high signal intensity within the lunate (indicated by white arrow). He was diagnosed with Lichtman I Kienböck’s disease and underwent a UHR-CT scan. Coronal (E), sagittal (F), and axial (G) UHR-CT images demonstrated focal trabecular microfracture of the affected lunate, corresponding to the area of high signal intensity on T2-weighted MRI (indicated by white arrow). The patient was treated conservatively with splint immobilization. MRI, magnetic resonance imaging; UHR-CT, ultra-high-resolution computed tomography.

Figure 3 A 44-year-old female presented with right wrist pain with limited range of motion. The patient had no history of other diseases. Posteroanterior (A) and lateral (B) radiographs of the right wrist showed flattened and fragmented lunate with the radioscaphoid angle greater than 60°. Coronal (C) T1-weighted MRI image showed diffuse hypointensity of the lunate, whereas coronal (D) and sagittal (E) T2-weighted MRI images depicted diffuse hyperintensity of the lunate. She was diagnosed with Lichtman IIIC Kienböck’s disease. Coronal (F), sagittal (G), and axial (H) UHR-CT images demonstrated lunate fragmentation with disordered and impaired trabecular structure, accompanied by uneven bone intensity, trabecular thickening, and extensive bone resorption. The patient subsequently underwent lunate excision combined with tendon ball arthroplasty. MRI, magnetic resonance imaging; UHR-CT, ultra-high-resolution computed tomography.

Quantitative assessment of UHR-CT findings

Quantitative comparison of the trabecular morphological parameters on UHR-CT were presented in Tables 2,3.

Reference vs. normal alignment group

The BV/TV was higher in the normal alignment group (0.45±0.04) than in the reference group (0.40±0.02), with a large effect size (Hedges’ g =1.36, 95% CI: −0.61 to 3.33). Tb.Th increased from 539±38 µm in the reference group to 612±56 µm in the normal alignment group (Hedges’ g =1.40, 95% CI: −0.58 to 3.38). Conversely, Tb.Sp decreased from 1,022±234 to 776±92 µm (Hedges’ g =−1.09, 95% CI: −2.99 to 0.82).

Normal alignment vs. malalignment group

Compared with the normal alignment group, the malalignment group demonstrated higher BV/TV (0.66±0.06 vs. 0.45±0.04; Hedges’ g =3.20, 95% CI: 0.42 to 5.98), greater Tb.Th (721±9 vs. 612±56 µm; Hedges’ g =2.18, 95% CI: −0.35 to 4.71), and reduced Tb.Sp (776±92 vs. 521±70 µm; Hedges’ g =−2.50, 95% CI: −4.78 to −0.22).

Based on the above, a clear graded pattern was observed across the three groups for each parameter, with progressive changes from reference to normal alignment to malalignment group (Figure 4). Although some confidence intervals included zero, all effect sizes were large, suggesting biologically meaningful microstructural differences and the exploratory nature.

Figure 4 Bar plots showing quantitative assessment of the trabecular morphological parameters on UHR-CT across the reference, normal alignment, and malalignment groups. BV/TV, bone volume fraction (bone volume/total volume); Tb.Th, trabecular thickness; Tb.Sp, trabecular spacing; UHR-CT, ultra-high-resolution computed tomography.

Discussion

This exploratory study is the first to evaluate the in vivo trabecular microstructure of the lunate in patients with Kienböck’s disease using UHR-CT, providing preliminary insights into microstructural progression of this disease.

In clinical practice, the diagnosis of Kienböck’s disease is typically based on patient history, clinical presentation, and imaging examinations. Conventional imaging modalities, including X-rays, CT, and MRI, can detect changes in bone density and morphology but provide limited information on trabecular levels alterations at different disease stages due to their low spatial resolution. In Lichtman stage I, the lunate generally appears normal on plain radiographs or CT, while MRI typically shows uniformly decreased signal intensity on T1-weighted images and increased signal intensity on T2-weighted images (24). However, in the present study, the UHR-CT images of stage I Kienböck’s disease revealed focal trabecular microfractures within the lunate, suggesting that UHR-CT may detect early structural compromise of the lunate before gross morphological deformation becomes apparent on plain radiographs. In addition, when correlated with MRI, we found that the microfractures or necrotic areas identified on UHR-CT corresponded to areas of high signal intensity on T2-weighted images, supporting the previously reported hypothesis that synovial fluid may infiltrate the lunate from the fracture lines and show as a high T2 signal (25). Historically, Kienböck proposed that a primary nutritional disturbance of the lunate may precede secondary fracture of weakened bone. Accordingly, the trabecular microfractures observed on UHR-CT may reflect secondary structural failure in compromised bone rather than the initiating cause of osteonecrosis. As UHR-CT directly depicts trabecular microarchitecture, it may serve as a complementary tool to MRI by providing additional staging-relevant microstructural information. Therefore, we believed it may be integrated with conventional imaging modalities to refine clinical staging system. Moreover, it can also be used to monitor trabecular changes to evaluate the efficacy of different treatment strategies.

Previous in vitro micro-CT studies investigated the trabecular microstructure parameters of the lunate. However, due to specimen limitations, these analysis had been limited to stage IIIB or more advanced Kienböck cases. By comparing cadaveric specimens with excised stage IIIB Kienböck lunates, researchers found that the Kienböck lunates exhibited increased BV/TV, Tb.Th, but decreased Tb.Sp (10,12,13). Unlike these studies, the introduction of UHR-CT allows in vivo assessment of trabecular microstructure in patients at earlier stages. In our study, quantitative UHR-CT analysis revealed a consistent, biologically plausible gradient of trabecular alteration, with trabecular bone becoming progressively denser and thicker from reference to normal alignment and finally to malalignment group. Together with previous research, these findings suggested that such trabecular bone changes may represent a reparative or adaptive remodeling response to chronic injury (10,12). Importantly, our results extend previous in vitro observations to in vivo imaging of clinical patients. Moreover, the observed changes in trabecular parameters raise the possibility that metrics derived from UHR-CT may serve as potential indicators for monitoring disease progression or predicting lunate collapse.

Our study has several limitations. First, the sample size was small, therefore, the findings should be regarded as preliminary and interpreted with caution, and definitive conclusions cannot be drawn. Second, although these patients received different treatments, follow-up imaging with UHR-CT was not performed to monitor subsequent trabecular bone changes, which should be addressed in future research. Third, because patients were grouped by carpal alignment status for exploratory purposes instead of being analyzed by Lichtman stage, robust stage-stratified comparisons were not feasible, and stage-specific threshold values based on trabecular parameters cannot be reliably defined in the present cohort. Future studies with larger sample size and longitudinal follow-up are warranted to validate these findings. Furthermore, establishing threshold values of trabecular parameters at different disease stages and integrating them with artificial intelligence or machine learning may help clinicians predict the risk of lunate collapse and enable early intervention.

Conclusions

In conclusion, our study is the first to demonstrate the feasibility of using UHR-CT for in vivo evaluation of lunate trabecular microstructure in patients with Kienböck’s disease. It is expected to become a valuable examination for early diagnosis, staging, and follow-up of Kienböck’s disease.

Acknowledgments

None.

Footnote

Funding: This work was supported by Natural Science Foundation of Beijing Municipality (No. 7222087).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-1-2822/coif). All authors declared that this study was supported by Natural Science Foundation of Beijing Municipality (No. 7222087). The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the institutional ethics board of Beijing Jishuitan Hospital, and individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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