Patho-morphogenetic remodeling of a severely atrophic unilateral right lower limb: a calibrated gross–radiographic case report

Abstract Bone and muscle remodel jointly in response to neural drive and mechanical loading, and both undergo profound degeneration under chronic disuse or denervation. Quantitatively calibrated descriptions of such extreme remodeling at single-limb level, integrating radiology with gross and cross-sectional anatomy, remain scarce. We report a formalin-fixed right lower limb from an elderly male cadaver showing severe unilateral atrophy. Premortem anteroposterior radiographs of the knee and foot, each bearing a 10-mm scale marker, were used to derive a distal-diaphyseal cortical index for the tibia and fibula, the ankle plantar-flexion angle, and heel-pad thickness. The limb then underwent layered dissection and mid-thigh cross-sectioning to quantify compartmental muscle area fractions. The distal tibial and fibular cortical indices were 0.131 and 0.433, respectively, indicating extreme cortical thinning of the tibia with relatively spared fibular cortex. The ankle was fixed in approximately 34.9° of plantar flexion, and the heel pad measured 9.8 mm. Only about 12.5% of the mid-thigh cross-section consisted of contractile muscle (anterior compartment 13.3%, medial 3.3%, posterior 20.4%), with extensive fatty replacement. Radiographs and anatomical findings were concordant for diffuse osteopenia, tendon prominence, and severe myosteatosis. Taken together, the calibrated metrics support long-standing disuse with probable partial denervation of this limb. Beyond documenting an extreme phenotype of coupled bone–muscle degeneration, this case illustrates a simple, reproducible workflow for quantitative analysis in single-case musculoskeletal pathology using visible scale references and explicitly defined regions of interest.