МОРФОЛОГІЧНІ ЗМІНИ В СИСТЕМІ «ГРУДИНА − РЕБРА − ХРЕБЕТ» ПІСЛЯ МОДЕЛЮВАННЯ МЕХАНІЧНОГО НАПРУЖЕННЯ В ЕКСПЕРИМЕНТІ

Chest wall deformities frequently coexist with spinal pathology. Our histological investigations reveal not only distinct morphological alterations but also significant changes in the physicochemical properties of costal cartilage compared to healthy controls. Despite these findings, the precise pathogenetic mechanisms connecting localized cartilage lesions to progressive chest wall deformity development remain incompletely understood. In this experimental study using a rat model, we aimed to systematically analyze morphological changes in the sternum-ribs-spine biomechanical system under sustained mechanical stress and examine the complex interrelationships among its structural components. The research cohort comprised 14 rats, with 8 subjects undergoing surgical induction of spinal deformity. Comprehensive radiographic evaluations were conducted immediately post-operation and at 1, 2, and 3-month intervals to quantify spinal deformity angles. Parallel morphological assessments at 1 and 3 months employed a validated semiquantitative scoring system to evaluate temporal changes throughout the biomechanical system. Our findings demonstrate progressive structural deterioration across all system components. The costovertebral joints, intervertebral discs, and vertebral endplates exhibited the most severe degenerative changes, characterized by: fibrous cartilage dissection, tissue fragmentation with distinctive ribbon-like proliferations, and pathological detritus accumulation within joint spaces. Rib heads showed marked structural compromise including deformation, cartilage layer attenuation, and necrotic foci formation. Intervertebral discs displayed nucleus pulposus degradation, annulus fibrosus integrity loss, chondrocyte depletion, and reduced cellular density. Vertebral endplates manifested cavitary lesions, disrupted chondrocyte columnar organization, and extensive apoptotic activity. Notably, by the 3-month endpoint, while persistent degenerative changes predominated, we observed localized reparative phenomena including fibrocartilage proliferation zones and measurable improvement in specific regions (most significantly in costovertebral joints, with severity scores decreasing from 2.3 to 1.5 points). However, complete architectural restoration remained elusive. Concomitant musculoskeletal involvement was evident through pathological muscle changes: cross-striation disruption, sarcomere disorganization, fiber homogenization, and myocyte nuclear hypertrophy. These results establish that chronic mechanical loading induces comprehensive structural compromise throughout the sternum-ribs-spine system. The persistence of degenerative changes at 3 months post-intervention suggests both partial irreversibility of damage and limited endogenous repair capacity under sustained biomechanical stress. Importantly, our data confirm a bidirectional pathological relationship, with spinal degeneration actively exacerbating anterior thoracic wall deformation. These insights significantly advance our understanding of chest wall deformity pathogenesis and provide a scientific foundation for developing targeted corrective interventions and rehabilitation protocols.