A periprosthetic fracture is a fracture that occurs at the location of the prosthesis. This includes periprosthetic fractures following artificial joint replacement and also periprosthetic fractures following partial internal fixation. They are commonly caused by trauma, osteolysis, pathology, aging, or excessive wear. They often occur at the proximal end of the joint prosthesis or around the prosthesis, either when the prosthesis is placed during surgery or, more commonly, after surgery. In the elderly, periprosthetic fractures can occur with very low violence and are often highly complicating and disabling, even fatal. Although periprosthetic fractures can occur in every artificial joint in the body, they occur more frequently in the lower extremities because of weight bearing, Zhang Lihai of the Department of Traumatology, Beijing 301 Hospital. In elderly patients with periprosthetic fractures, the local biological and mechanical characteristics are both the cause of the fracture and affect its treatment and prognosis. Implantation of an artificial prosthesis can disrupt the local blood supply, and reduced bone volume and loosening of the prosthesis can reduce its mechanical stability. Bone loss or resorption may also be due to poor placement or misalignment of the initial replacement, resulting in elevated stresses on the surrounding bone due to abnormal physiological loading. Although each case of periprosthetic fracture is different from each other, all should be treated individually. Case: Patient Male 79 years old, periprosthetic fracture after reverse shoulder arthroplasty. The patient had undergone multiple surgeries due to a failed proximal humeral fracture fixation infection and finally used a reverse shoulder arthroplasty to obtain good shoulder function. This time, he inadvertently fell again, resulting in a periprosthetic fracture and a concomitant injury to the radial nerve. Difficulties: poor soft tissue condition after multiple local surgeries; cemented prosthesis with weak bone tissue activity; very thin humerus with osteoporosis and insufficient bone mass; occupied prosthesis with difficulty in fixation; radial nerve contusion, indicating that the nerve is being trapped at the fracture break. The patient has been treated with a reverse shoulder joint replacement with no chance of revision in case of failure. Difficulty level: Grade IV Surgical treatment: Release the entrapped nerve and remove the excess bone cement. Strong fixation was obtained using a nail plate system combined with titanium cables. Extensive bone grafting and structural bone grafting to promote bone healing. Postoperatively, the nerve injury gradually recovered, the fracture healed well, and the joint functioned well.