Li, a 79-year-old female, was admitted to the hospital with the main reason of “trauma to the left elbow joint with swelling and pain caused by a fall, and functional limitation of movement for 2 months”. Preoperative functional status: poor flexion activity of the left elbow joint, difficulty in dressing herself, difficulty in carrying bowls and eating. Specialized examination: deformity and swelling of the left elbow joint, loss of posterior elbow triangle alignment, deformed bone mass could be found, positive pressure pain in the medial and lateral elbow joints and longitudinal percussion pain in the left upper limb, extension of the left elbow joint about -25°, flexion about 33°, free movement of the left wrist joint and all fingers, normal tenderness and blood flow in the left upper limb. CT suggests: old fracture of the left elbow joint with traumatic arthritic changes, comminuted old fracture of the lower humerus with blurred fracture lines, dislocation of the severed end, scattered lamellar slightly dense shadow around, poor alignment of the left elbow joint, posterior displacement of the ulna and poorly defined soft tissue level around. Diagnosis: old left distal humerus fracture (through-condylar fracture) Family request: able to take care of himself (dressing, combing hair, carrying bowls, fetching things, etc.) Treatment: after admission to the hospital, all routine examinations were actively improved, and after excluding contraindications to surgery, a posterior ulnar hawk’s-jaw osteotomy of the distal humerus through-condylar fracture was performed by incision and internal fixation, and an iliac bone graft was taken. Postoperative recovery: 10 days after the operation, the left elbow joint extension was about -5° and flexion was about 95°, which could meet the basic needs of daily life.