Avascular necrosis of the femur is a painful condition marked by a disruption in the blood supply to the femoral head, which causes the femur bone to distort; characterized by pain and restriction of movements at the affected joint with a limp. The study aimed to provide a case of nontraumatic stage-4 avascular necrosis of the left femoral head with gross 40-degree adductor deformity. In this report, a 27-year-old female complained of pain in her left hip joint and difficulty in walking. She was a known case of pyogenic arthritis with 5 cm of true shortening on her left side and a gross 40-degree adduction deformity of her left leg. According to Ficat and Arlet's grading system, an X-ray showed stage-4 avascular necrosis of the left femoral head. For this, she was managed with adductor tenotomy, medications, and physiotherapy management with a one-month rehabilitation protocol. A physiotherapy intervention consists of a non-weight-bearing phase and a weight-bearing phase. At the time of her physiotherapy discharge, the patient experienced alleviation from symptoms and achieved functional mobility that she had previously been unable to tolerate owing to pain. As a result, physical therapy rehabilitation has been proved to be highly beneficial. This case study concludes that multidisciplinary team including medical, surgical approach and physiotherapy rehabilitation played a vital role in reducing pain; enhance muscle strength, functional independence, and quality of life in patients with stage 4 avascular necrosis of the femur followed by pyogenic arthritis.