Stress fractures of lower limb amputation stumps: clinical, radiological, and morphological features

Background. Stress fractures of amputation stumps of the lower extremities are an understudied complication of prosthesis use that develops against the background of impaired bone remodeling and repeated mechanical stress. Aim: to investigate the clinical, radiological, and morphological features of stress fractures of lower limb amputation stumps and to determine their relationship with the ti­ming and nature of prosthetic rehabilitation. Materials and ­methods. Twenty-three patients aged 21–49 years with stress fractures of lower limb amputation stumps were examined at various times after prosthetic fitting. A clinical assessment of pain syndrome and gait function was performed, as well as an X-ray examination with analysis of the condition of the cortical layer and trabecular architectonics, morphological examination of bone tissue based on materials from revision surgical interventions. Additionally, an analysis of systemic and local risk factors for stress fractures was performed. Statistical processing of the results was made using parametric methods, with a statistical significance level of p < 0.05. Results. It was found that early stress fractures (≤ 4 months after prosthetic fitting) form against the background of incomplete structural and functional formation of the stump and active reparative osteogenesis; in 72 % of cases, they occur within the first 2.5 months and are accompanied by moderate disturbances in cortical and trabecular architectonics. Fractures in this group were localized mainly in areas of maximum mechanical stress and anatomical vascular vulnerabi­lity. Late stress fractures (> 4 months after prosthetic fitting) were characterized by severe osteoporosis, hyperostosis, cystic remodeling of the medullary canal, and gross disruption of the trabecular structure, reflecting chronic pathological remodeling of bone tissue. Bilateral amputation was associated with accelerated formation of stress fractures regardless of the timing of prosthetic replacement. Conclusions. Stress fractures of lower limb amputation stumps are the result of an imbalance between bone remodeling processes and repeated mechanical stress. The timing and quality of prosthesis use, gait biomechanics, and a combination of systemic and local factors determine the nature and rate of damage development, which justifies the need for an individualized approach to prosthetic rehabilitation and a phased load dosage.