To arrive at the diagnosis of the patient's condition, we need to analyze the given information and x-ray findings associated with the previous history of Road Traffic Accident (RTA) and symptoms of pain and swelling. Let's objectively consider the characteristics of each potential diagnosis:
- Osteogenic sarcoma: A malignant bone tumor more common in children and adolescents. It often presents with a mass, bone pain, and localized swelling.
- Ewing's sarcoma: Another type of malignant bone tumor, typically affecting younger individuals, presenting with pain and a palpable mass. It commonly involves the diaphysis of long bones.
- Chronic osteomyelitis: A chronic bone infection often following an injury or surgery. It is characterized by persistent pain and swelling at the site with potential alteration in the structure on x-ray.
- Multiple myeloma: A cancer of plasma cells, more common in older adults, which can cause bone pain and fractures. It usually appears in the skull, spine, pelvis, and ribs.
In the case described, the presence of pain and swelling at the same site of previous RTA, combined with the x-ray findings, suggests the possibility of a chronic bone infection or damage resulting from the trauma experienced during the RTA.
Chronic osteomyelitis often develops after an open fracture or surgical procedure that might have contaminated the site with bacteria, leading to persistent infection and inflammation, hence the symptom pattern described.
Given these considerations and the nature of the question, the most probable diagnosis is:
Chronic osteomyelitis