Differential Diagnosis for 87-year-old Male with Left Hip Pain

Single Most Likely Diagnosis

• Osteoarthritis (OA) of the Hip: Given the patient's age, the description of the pain (mild to moderate, aching, radiating from hip to knee), and the physical exam findings (tender to the greater trochanter and glutes, some pain with passive internal rotation of the hip), OA is a common condition in this age group that matches the clinical presentation.

Other Likely Diagnoses

• Trochanteric Bursitis: The tenderness over the greater trochanter and pain with passive internal rotation could also suggest trochanteric bursitis, a condition that involves inflammation of the bursa over the greater trochanter.
• Gluteal Strain or Tendinopathy: Given the pain location and the involvement of the glutes, a strain or tendinopathy of the gluteal muscles or tendons could be considered, especially in an active individual.
• Lumbar Radiculopathy: Although the patient denies numbness or tingling, lumbar radiculopathy could still be a consideration, especially if the pain radiates to the knee, as it might suggest nerve root irritation.

Do Not Miss Diagnoses

• Hip Fracture: Despite no reported trauma, the possibility of a stress fracture or an occult fracture, especially in an elderly patient, must be considered due to the potential for significant morbidity and mortality if missed.
• Avascular Necrosis (AVN) of the Femoral Head: This condition can present with hip pain and is a significant concern in older adults, especially if there's a history of steroid use or other risk factors, due to its potential for rapid progression to severe arthritis.
• Infection (Septic Arthritis): Although less likely without systemic symptoms or a clear source of infection, septic arthritis is a medical emergency that requires prompt diagnosis and treatment to prevent serious complications.

Rare Diagnoses

• Piriformis Syndrome: This condition involves the piriformis muscle compressing the sciatic nerve and could present with pain radiating down the leg, but it's less common and typically associated with more specific symptoms like sciatica.
• Neoplastic Processes (Bone Tumors): While rare, primary or metastatic bone tumors could present with hip pain and should be considered, especially if there's a known history of cancer or if the pain is persistent and unexplained by other diagnoses.