Differential Diagnosis for 85-year-old Female with R Leg Pain

Single Most Likely Diagnosis

• Periarticular or stress fracture around the knee or proximal tibia: Given the patient's recent fall and the nature of her pain, which worsens when she takes pressure off, a stress or periarticular fracture is highly plausible. The fact that she landed on her right side, mostly on the hip, and has pain around the knee and proximal tibia, suggests a possible fracture in this area, especially considering her age and potential for osteoporosis.

Other Likely Diagnoses

• Osteonecrosis of the femur or tibia: The patient's recent steroid injection could be a risk factor for osteonecrosis, especially if she has been on long-term steroid therapy. The pain pattern and recent trauma also fit with this diagnosis.
• Soft tissue injury or bruising: Although the patient had a fall a week ago, soft tissue injuries can still cause significant pain, especially if the patient is taking pressure off the affected area, which might exacerbate the pain due to swelling or hematoma formation.
• Bursitis or tendinitis: The location of the pain around the knee and proximal tibia could suggest bursitis or tendinitis, possibly exacerbated by the fall or the steroid injection.

Do Not Miss Diagnoses

• Deep Vein Thrombosis (DVT): Given the patient's age, recent fall, and immobilization, DVT is a critical diagnosis not to miss. Although the pain pattern might not be typical, DVT can present with pain in the leg, especially if the patient is not moving much.
• Infection (e.g., cellulitis or osteomyelitis): Especially with the recent steroid injection, the patient might be at increased risk for infections. While less likely, infection is a diagnosis that could have severe consequences if missed.
• Neurological causes (e.g., neuropathy or radiculopathy): Although less directly related to the fall, neurological causes of pain should be considered, especially if the pain pattern is atypical or if there are other neurological symptoms.

Rare Diagnoses

• Bone tumor or metastasis: While rare, a bone tumor or metastasis could present with pain in the affected area, especially in an elderly patient. The recent fall might have coincidentally drawn attention to an existing condition.
• Vascular insufficiency or claudication: If the patient has significant vascular disease, pain in the leg could be related to insufficient blood flow, especially with activity or changes in position.