Lower extremity: hip, knee, fibula, ankle and foot

4 min read. Updated October 9, 2026.Founders

Psoas

  • A tight iliopsoas makes hip extension painful or limited, causes low back and hip pain, and gives a positive Thomas test.
  • The traditional psoas pattern: a flexed L1 or L2 rotated and sidebent toward the tight side, the pelvis shifted away from it, and often a tight piriformis on the opposite side with a related oblique sacral pattern.
  • Psoas spasm can be secondary to appendicitis or other retroperitoneal irritation, not only a muscle problem.

The rest of this guide is for founders

Founders get every guide, endless cases with an AI tutor, and Anki export of their misses. Here is what is inside:

  1. Psoas
  2. Piriformis
  3. Knee
  4. Fibular head
  5. Ankle and foot

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