Cotton Test | Syndesmosis Injury | Ankle Assessment

The syndesmosis is the interosseous membrane that connects the tibia to the fibula. A syndesmosis rupture can result from both inversion trauma and, more importantly, from trauma to the ankle joint in external rotation and dorsiflexion. According to the guideline on ankle injuries of the Dutch Association of Physical Therapists, KNGF, the incidence of syndesmosis injury among all ankle injuries is approximately 1%.
The Cotton test is designed to test for syndesmosis instability caused by the separation of the tibia and fibula, which are held together by four different ligaments. According to Beumer et al. (2002), the Cotton test has a sensitivity of only 25% and its specificity was not measured.

To perform this test, stabilize the distal tibia and fibula with one hand and apply a lateral translation force to the foot with your other hand.

The test is positive for a syndesmosis lesion with a translation of more than 3 to 5 mm or if a clunk is heard or felt.

Other common orthopedic tests for syndesmosis injuries are:

• Dorsiflexion External Rotation Stress Test / Kleiger’s Test
• Syndesmosis Ligament Tenderness
• Fibular Translation Test
• Syndesmosis Squeeze Test
• Syndesmosis Signs & Symptoms
• Crossed Leg Test
• Heel Thump Test

Beumer, A., Swierstra, B. A., & Mulder, P. G. (2002). Clinical diagnosis of syndesmotic ankle instability: evaluation of stress tests behind the curtains. Acta Orthopaedica Scandinavica, 73(6), 667-669.ISO 690