Evaluation of Kienböck's disease through distal radius sagittal plane analysis.

Background: Kienböck's disease poses challenges in plate placement during radial shortening osteotomy due to steep metaphyseal inclination of the distal radius. While coronal plane analyses have been extensively studied, sagittal plane deformities remain underexplored. This study addresses the anatomical variations in the sagittal plane associated with Kienböck's disease. The primary questions include: (1) Are sagittal plane deformities more prevalent in Kienböck's disease? (2) Do these deformities influence treatment strategies or outcomes?

Hypothesis: We hypothesize that anatomical variations in the sagittal plane of the distal radius are significantly associated with Kienböck's disease, potentially impacting surgical plate fitting and lunate loading.

Patients and methods: This retrospective study included 43 patients with Kienböck's disease confirmed by imaging, compared to a matched control group of 43 individuals. Lateral wrist radiographs were analysed for palmar tilt (PT), teardrop angle (TDA), teardrop inclination angle (TIA), and tear height ratio (RTH). Lichtman stages were determined via MRI, and functional outcomes were assessed using the Patient-Rated Wrist Evaluation (PRWE). Statistical analyses compared these parameters between the groups.

Results: Kienböck patients exhibited a significantly lower TDA (58.1 ± 7.9 vs 65.8 ± 3.4, p = 0.0001) and higher TIA (35.9 ± 5.0 vs 29.6 ± 3.53, p = 0.0000) compared to controls. PT and RTH did not differ significantly. These findings suggest distinct sagittal plane deformities in Kienböck's disease, with potential implications for surgical interventions.

Discussion: While coronal plane parameters have been the focus in Kienböck's disease, this study highlights the importance of sagittal plane analyses. The identified differences in TDA and TIA may explain challenges in surgical plate fitting. Further biomechanical studies are required to validate these findings and optimise treatment strategies.

Level of evidence: III; Diagnostic.