Execution
- 1Position the patient sitting with the leg hanging over the table and the knee flexed to 90 degrees.
- 2Stabilize the lower leg with one hand.
- 3Hold the foot in plantigrade at approximately 90 degrees.
- 4Apply passive external rotation stress to the foot and ankle.
- 5Ask whether pain is produced over the anterior or posterior tibiofibular ligaments or interosseous membrane.
Positive outcome
Pain over the syndesmosis region during external rotation stress is positive for high ankle sprain. Medial pain with talar displacement away from the medial malleolus may suggest deltoid ligament injury rather than isolated syndesmosis injury. Pain location should be recorded precisely.
Studies
| Study | Reliability | Sn | Sp | LR+ | LR− |
|---|---|---|---|---|---|
| Sman et al. (2013) | prospective diagnostic accuracy, n=87, MRI reference | 71 | 63 | 1.93 | 0.46 |
| Sman et al. (2015) | systematic review follow-up | NA | NA | NA | NA |
CommentMagee describes the external rotation stress test as a core syndesmosis provocation test. Sman 2013 found Sn 71%, Sp 63%, LR+ 1.93 against MRI reference — a positive test increases the likelihood of syndesmosis injury about 2-fold. Combined with positive syndesmosis ligament palpation, OR for syndesmosis injury was 3.9 (p=0.004). The literature supports using it with palpation, squeeze, and functional findings rather than alone. Because stress may also provoke deltoid injury, medial clear-space concern should lead to imaging or medical review.
Moderate Clinical Value