L3+L4: Patellar Tendon Reflex

Execution:

  1. The patient is in sitting or supine position
  2. The examiner bends the patient’s contralateral knee slightly and keeps it supported, so that the patient can completely relax
  3. The examiner then hits the patellar tendon above the tibial tuberosity with the reflex hammer that is held with a relaxed wrist between thumb and index finger

 

Positive Outcome: Hyporeflexia compared to the other side

Study Reliability Sn Sp LR+ LR-
Hancock et al. (2011): L3/L4 Disc Herniation NA 50 83 2.92 0.6
Hancock et al. (2011): L4/L5 Disc Herniation NA 19 82 1.03 0.99
Iversen et al. (2013) NA 67 83 3.96 0.4
Comment: The Patellar Tendon Reflex has a weak association with a lumbar disc herniation at level L3/L4, possible affecting nerves L3 or L4