Final answer:
The patient has used a patellar tendon bearing prosthesis for at least 20 years.
Step-by-step explanation:
The patient has used a patellar tendon bearing prosthesis for at least 20 years. This type of prosthetic device, which is designed to support the knee joint, has been in use for over two decades. The X-rays shown in Figure 5.3 demonstrate a post-operative knee joint replacement, indicating that the patient has undergone an artificial knee replacement surgery.