Bone Density, Microarchitecture, and Geometry Assessment in Patients with Pachydermoperiostosis Using Second-Generation High-Resolution Peripheral Quantitative Computed Tomography: A Case-Control Study.

Pachydermoperiostosis (PDP) is a rare genetic disorder manifesting with periostosis, clubbing, and thickened skin. The impact of PDP on bone density and microarchitecture is underexplored despite the potential derangement in bone health due to systemic inflammation. This cross-sectional case-control study was conducted in a tertiary care center in north India from July 2022 to July 2023. We compared treatment naïve PDP patients (n = 8) with age and BMI-matched apparently healthy controls. All participants underwent clinical examination and estimation of biochemical parameters including calcium, phosphorus, alkaline phosphatase, 25(OH)D, and iPTH. Bone turnover markers C-terminal telopeptide of type I collagen (CTX) and procollagen type I N-propeptide (P1NP) were also assessed. All patients underwent areal and volumetric bone density measurements using dual-energy X-ray absorptiometry (DXA) and high-resolution peripheral quantitative computed tomography (HR-pQCT). HR-pQCT analysis revealed diminished cortical volumetric bone mineral density and altered microarchitecture in PDP patients at the radius and tibia, characterized by increased cortical porosity. Bone geometry assessment demonstrated increased cross-sectional bone area both in the cortical and trabecular compartments. Finite element analysis (FEA) indicated a substantial reduction in failure load, cortical and trabecular von Mises stress (VMS) at the tibia and stiffness at the radius in PDP patients compared to controls. PDP patients had similar biochemical and bone turnover parameters to controls. Individuals with PDP show reduced cortical vBMD with disrupted bone microarchitecture. These changes may reflect PGE2-mediated inflammation and bone resorption, suggesting increased fracture risk and the need for ongoing monitoring.