The article deals with adult spinal deformity (ASD), which leads to progressive decompensation of the spine and lower limbs. This decompensation reduces mobility and increases the risk of falls in the elderly. The compensatory chain includes posterior pelvic tilt, hip hyperextension, knee flexion, and ankle dorsiflexion. Long-term maintenance of these compensatory positions leads to degenerative changes in the joints of the lower limbs. The authors propose a "residual compensation potential" (RCP) evaluation framework that combines EOS imaging, 3D gait analysis, and electromyography (sEMG). RCP is intended to quantify the remaining compensatory capacity of the joints and to categorize patients for better planning of surgical and rehabilitation treatment. Assessment of ASD should include functional status of the lower extremities, not just static spinal alignment.