Effective lower extremity reconstruction requires a thorough understanding of anatomy, encompassing bones, muscles, vascular structures, and sensorial innervation. This chapter provides a comprehensive overview, emphasizing the importance of precise evaluation for case-specific planning. Lower extremity anatomy, including bones, muscles, vascular structures, and sensorial innervation, is explored. The examination process involves inspection, palpation, temperature assessment, pulse examination, neurological examination, and sensory examination. Notably, a grading system is presented for deep tendon reflexes and sensory perception. Additionally, diagnostic tools such as imaging studies, electrodiagnostic studies, bone scans, arthroscopy, joint aspiration, and the ankle-brachial index are discussed, offering valuable insights for reconstructive surgeons. This holistic approach to lower extremity examination and diagnostics is essential for formulating precise surgical plans, ensuring optimal outcomes, and addressing a myriad of musculoskeletal, neurological, vascular, and dermatological conditions in the lower limbs.