Prone Knee Extension Test – Saphenous Nerve Bias

Purpose of Prone Knee Extension Test – Saphenous Nerve Bias: To determine if the tension along the saphenous nerve contributes to the neurologic symptoms associated with radiculopathy (1, 2).

Patient position: Prone lying (3) and side-lying (4).

Examiner position: Standing beside the patient, at the side of the limb to be tested.

Procedure: Perform the limb/joint positioning sequence in the following order:

1. Neutral alignment at the cervical, thoracic and lumbar spine, while the patient is on prone lying (3, 5),
2. Hip extension and abduction (to the end of available range), followed by knee extension (with the examiner’s one hand holding the anterior aspect of the patient’s distal thigh and the other hand holding the patient’s foot),
3. Hip lateral rotation (6) or medial rotation (7), followed by ankle dorsiflexion and eversion,
4. Sensitizing position: Ankle plantarflexion if the symptoms are above the knee, hip medial rotation if the symptoms are above the knee, or contralateral side flexion of the spine (6, 8).

Outcome: This test is positive if (a) the limb/joint positioning sequence reproduces symptoms associated with radiculopathy, (b) the sensitizing position reproduces symptoms, and (c) there is a repeatable and measurable asymmetry between both sides along with the reproduction of symptoms.

Reference:

1. Butler DS, Matheson J. The Sensitive Nervous System: Noigroup Publications; 2000.
2. Kopell HP, Thompson WAL. Peripheral entrapment neuropathies: Williams & Wilkins; 1963.
3. Butler DS, Jones MA, Gore R. Mobilisation of the nervous system: Churchill Livingstone Melbourne etc.; 1991.
4. Porr J, Chrobak K, Muir B. Entrapment of the saphenous nerve at the adductor canal affecting the infrapatellar branch – a report on two cases. The Journal of the Canadian Chiropractic Association. 2013;57(4):341-9.
5. Magee DJ. Orthopedic Physical Assessment: Elsevier Health Sciences; 2013.
6. Petty NJ, Ryder D. Musculoskeletal Examination and Assessment E-Book: A Handbook for Therapists: Elsevier Health Sciences; 2017.
7. Shacklock M. Clinical neurodynamics: a new system of musculoskeletal treatment: Elsevier Health Sciences; 2005.
8. Loudon JK, Swift M, Bell S. The Clinical Orthopedic Assessment Guide: Human Kinetics; 2008.