Differential Diagnosis

The patient's symptoms and radiographic findings suggest a range of possible diagnoses. Here is a categorized differential diagnosis:

• Single most likely diagnosis

  • Osteoarthritis of the hip: The patient's x-ray shows mild degenerative changes in the hips bilaterally, and he experiences aching pain in the groin and hip that radiates to the knee, especially with prolonged standing and walking. Limited left leg external rotation and pain on flexion of the hip passive range of motion also support this diagnosis, given the mechanical stress from golfing.

• Other Likely diagnoses

  • Trochanteric bursitis: The patient's pain location and radiation pattern, along with the limitation in external rotation, could be consistent with trochanteric bursitis, especially given the repetitive stress from golfing.
  • Labral tear: The pain on flexion and limited external rotation could suggest a labral tear, particularly in the context of a golfer who pivots on the left leg, causing repetitive stress to the hip joint.
  • Piriformis syndrome: Although less likely given the radiographic findings, the radiation of pain down to the knee and the specific activities that exacerbate the pain could suggest piriformis syndrome, especially if the piriformis muscle is irritated or tight.

• Do Not Miss diagnoses

  • Avascular necrosis of the femoral head: This condition could present with hip pain and limited range of motion, and it is crucial to diagnose early to prevent further damage. The patient's age and activity level, along with the radiographic findings, make this a "do not miss" diagnosis.
  • Infection or septic arthritis: Although less likely without systemic symptoms or a clear source of infection, any hip pain with limited range of motion and pain on movement warrants consideration of infection, given the potential for severe consequences if missed.
  • Metastatic disease or multiple myeloma: In older adults, hip pain and degenerative changes could be the first presentation of metastatic disease or multiple myeloma. A thorough history and additional diagnostic tests would be necessary to rule out these conditions.

• Rare diagnoses

  • Synovial chondromatosis: A rare condition characterized by cartilaginous nodules within the synovium, which could cause hip pain, limited range of motion, and locking or catching sensations.
  • Osteonecrosis of the femoral head due to a specific cause (e.g., steroid use, sickle cell disease): Depending on the patient's medical history, other causes of osteonecrosis could be considered, though these would be less common without specific risk factors.