Tibial External Rotation Test

Other Names

The TERT. Fig. 1-A With the patient sitting with the knee at 90° of flexion, internally rotate the leg. Fig. 1-B While holding the leg in the internally rotated position, ask the patient to forcefully extend the knee against the moderate manual resistance that you are providing. Fig. 1-C With the knee at 90° of flexion, externally rotate the leg. Fig. 1-D While holding the leg externally rotated, ask the patient to forcefully extend the knee against the moderate manual resistance that you are providing. Look for lateral subluxation of the patella or apprehension when the knee is at about 25° of flexion.

• Tibial External Rotation Test (TERT)
• External Rotation Patellar Instability Test
• Dynamic Tibial Rotation Test for Patella
• Patellar Subluxation External Rotation Test

---

Purpose

• Evaluate for patellar instability as a cause of knee pain

---

Description

• Patient seated with knee flexed to 90°
• Examiner internally rotates the tibia
• Patient performs active knee extension against moderate resistance
• Test is repeated with the tibia externally rotated
• Examiner observes for patellar tracking, subluxation, or apprehension
• Positive test:
  • Lateral patellar subluxation or apprehension
  • Occurs around ~25° of knee flexion
  • Present with external rotation but not internal rotation

---

Pathology

• Patellar Instability

---

Evidence

• Unknown

---

See Also

• Knee Pain
• Knee Anatomy
• Physical Exam Knee

---