Knee
ACL & PCL
Evidence: confirmed
Jerk Test of Hughston Special Test
Orthopedic Physical Examination & Clinical Assessment Guide
What is it used for?
- Diagnosing Anterolateral Rotatory Instability (ALRI) (ACL + Lateral Capsule).
- Similar to the Pivot Shift but performed in reverse (Flexion to Extension).
How to Perform
- Position: Patient supine, hip flexed 45°, knee flexed 90°.
- Action: Apply a Valgus stress and Internal Rotation to the tibia.
- Movement: Slowly extend the knee.
Interpretation of Results
- Positive Test: At ~20-30° of flexion, the tibia (which was subluxated anteriorly) suddenly reduces with a palpable 'jerk' or 'clunk'.
Clinical Context & Limitations
The Jerk Test of Hughston should be considered as one component of a comprehensive musculoskeletal assessment. No single special test has perfect diagnostic accuracy; thus, clinical decision-making should integrate test results with patient-reported symptoms, mechanism of injury, functional impairment, and relevant imaging.
Clinicians should be aware of potential false-positive results in patients with pain sensitisation, muscle guarding, or poor relaxation. For the Knee region, combining the Jerk Test of Hughston with complementary examination tests significantly improves overall diagnostic confidence.
References
- Magee, D. J. (2021). Orthopedic Physical Assessment.
