Differential Diagnosis for Left Sided Groin Pain

The patient presents with left sided groin pain that radiates to the left lower back, left bum cheek, and can extend down to the left lower knee, accompanied by a sensation of something being trapped or a pulling feeling. This pain is exacerbated by walking and has worsened over the last week, with some relief from naproxen and codeine. Based on these symptoms, the following differential diagnoses can be considered:

• Single Most Likely Diagnosis

  • Lumbar Radiculopathy or Sciatica: The pain radiating down to the knee, worsened by walking, and the feeling of something being trapped or a pulling sensation are classic symptoms for lumbar radiculopathy, often due to a herniated disc or spinal stenosis affecting the sciatic nerve.

• Other Likely Diagnoses

  • Trochanteric Bursitis: Inflammation of the bursa over the trochanteric area can cause pain in the groin, hip, and lower back, which can radiate down the thigh.
  • Piriformis Syndrome: The piriformis muscle can compress the sciatic nerve, leading to pain in the buttocks, hip, and down the leg, similar to sciatica.
  • Osteoarthritis of the Hip: Degenerative changes in the hip joint can cause groin pain that radiates to the knee, especially with weight-bearing activities like walking.
  • Sacroiliitis: Inflammation of the sacroiliac joint can cause pain in the lower back, buttocks, and sometimes radiate down the leg.

• Do Not Miss Diagnoses

  • Abdominal Aortic Aneurysm (AAA): Although less likely given the radiating pain pattern, an expanding AAA can cause lower back and groin pain and is a medical emergency.
  • Kidney Stones or Pyelonephritis: Severe pain in the flank or lower back that radiates to the groin could indicate a kidney stone or infection, both of which require prompt medical attention.
  • Spinal Infection or Abscess: Infections like osteomyelitis or discitis can cause severe back pain that radiates, and these conditions are medical emergencies.

• Rare Diagnoses

  • Neoplastic Processes: Tumors in the spine, hip, or surrounding soft tissues can cause progressive pain and neurological symptoms.
  • Chronic Compartment Syndrome: Increased pressure within a muscle compartment can cause pain, especially with activity, though it's less common in the presentation described.
  • Neurogenic Claudication: A condition related to spinal stenosis that causes pain, weakness, or fatigue in the legs and buttocks when walking or standing, relieved by rest.

Given the complexity and potential severity of some of these conditions, a thorough medical evaluation, including history, physical examination, and possibly imaging studies (like MRI for lumbar radiculopathy or abdominal ultrasound for AAA), is necessary to determine the exact cause of the patient's symptoms.