This study analyzed the inherent relation between arterial blood mass flow and muscle atrophy of residual limb to provide some necessary information and theoretical support for the clinical rehabilitation of lower limb amputees. Three-dimensional arterial model reconstruction was performed on both intact side and residual limb of a unilateral transfemoral amputee who is the subject. Then hemodynamic calculation was carried out to comparatively analyze the mass flow state at each arterial outlet of both lower extremities. The muscle atrophy ratio of residual limb was calculated by measuring the cross-sectional area of bilateral muscles. Based on the blood supply relationship, the correlation between arterial blood flow reduction ratio and muscle atrophy ratio was discussed. The results showed that the mass flow of superficial femoral arteries and lateral circumflex femoral arteries severely reduced. Meanwhile rectus femoris, vastus lateralis and vastus medialis which were fed by these arteries showed great atrophy too. On the contrary, the mass flow of deep femoral arteries and medial femoral circumflex arteries slightly reduced. Meanwhile gracilis, adductor longus, long head of biceps which were fed by these arteries showed mild atrophy too. These results indicated that there might be a positive and promotion correlation between the muscle atrophy ratio and the blood mass flow reduction ratio of residual limb during rehabilitation.
Muscle atrophy of the residual limb after lower-limb amputation is a disadvantage of amputees' rehabilitation. To investigate the biomechanics mechanism of muscle atrophy of the residual limb, we built a finite element model of a residual limb including muscle, skeletons and main vessels based on magnetic resonance images of a trans-femoral amputee, and studied the biomechanics effects of the socket of the lower-limb prosthesis on the soft tissue and vessels in the residual limb. It was found that the descending branch of the lateral femoral circumflex artery suffered the most serious constriction due to the extrusion, while that of the deep femoral artery was comparatively light. Besides, the degree of the constriction of the descending branch of the lateral femoral circumflex vein, femoral vein and deep femoral vein decreased in turn, and that of the great saphenous vein was serious. The stress-strain in the anterior femoral muscle group were highest, while the stress concentration of the inferior muscle group was observed at the end of the thighbone, and other biomechanical indicators at the inferior region were also high. This study validated that the extrusion of the socket on the vessels could cause muscle atrophy to some degree, and provided theoretical references for learning the mechanism of muscle atrophy in residual limb and its effective preventive measures.
To provide a reference for determining the hemodynamic environment of blood vessels and the nutrient supply of residual limbs, as well as for rehabilitation treatments aimed at reducing muscle atrophy after amputation, this study employed contrast-enhanced computed tomography technology to obtain angiographic images of the vascular system in residual limbs. A vascular model was established through three-dimensional reconstruction and mesh generation, followed by hemodynamic analysis using the finite element method. Based on the blood flow velocities in the femoral artery—0.09 m/s at rest, 0.23 m/s during exercise, and 0.32 m/s during steady-state exercise—the inlet velocities of the residual limb arteries were determined. Calculations yielded the inlet flow velocity, blood flow rate, and blood supply volume. As the inlet velocity increased, the mass flow rates in the superficial femoral artery and deep femoral artery showed the most significant increases, reaching 2.50E-3 kg/s and 2.67E-3 kg/s, respectively. In contrast, the blood flow in the lateral and medial femoral circumflex arteries did not exhibit significant changes. Increasing the inflow velocity did not significantly alter the minimal wall shear stress in the vessels. However, the maximum wall pressure in each vessel rose significantly with increased mass flow rate. Excessively high wall pressure may trigger atherosclerosis, particularly in higher-positioned vessels such as the superficial femoral artery. In addition, due to differences in blood supply, muscles experienced varying degrees of atrophy. Specific treatments for atherosclerosis should be considered during limb rehabilitation. Future research might explore combining rehabilitation training with other methods to promote localized muscle blood supply.
