Ankle & Foot
Structural & Biomechanical
Evidence: suggestive
Jack Test** Special Test
Orthopedic Physical Examination & Clinical Assessment Guide
What is it used for?
- Assessing hindfoot and subtalar flexibility in cases of flexible flatfoot.
- Evaluating the mechanical action of the plantar fascia (windlass mechanism).
How to Perform
- Position: Have the patient stand or sit with weight on the foot.
- Action: Manually dorsiflex the big toe.
- Observation: Watch for the formation of a medial arch. Dorsiflexing the toe should pull the plantar fascia, shorten the foot, and elevate the arch (windlass effect).
Interpretation of Results
- Positive Result (Normal/Flexible): The medial arch appears or increases when the toe is dorsiflexed.
- Negative Result (Rigid): The arch does not change, suggesting a rigid flatfoot.
Clinical Context & Limitations
The Jack Test** 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 Ankle & Foot region, combining the Jack Test** with complementary examination tests significantly improves overall diagnostic confidence.
References
- Jack Test Foot Flexibility - Orthofixar
- Magee, D. J. (2021). Orthopedic Physical Assessment (7th ed.). Elsevier.
