The investigators aimed to evaluate the efficacy of selective low volume ultrasound-guided blockades of the saphenous and obturator nerves on dynamic and rest pain 24-hours post-operatively for patients undergoing unilateral primary total knee arthroplasty.

A femoral nerve block is the recommended strategy in many surgical centers to supplement multimodal analgesic regime following total knee arthroplasty (TKA) (i.e. both for spinal and general anesthesia). However, a femoral nerve block will often result in quadriceps paralysis, and this will increase the risk for the patient to fall as long as the femoral block have effect. Thus, the search for sensory nerve blocks to stop pain after TKA is a very interesting topic. The saphenous nerve is a purely sensory nerve, and the posterior branch of the obturator nerve is a mixed nerve, where the motor component only affects part of the adductor major muscle.

Inclusion Criteria:

1. American Society of Anesthesiologists' physical classification I-III
2. Age ≥ 18 years undergoing primary unilateral total knee arthroplasty

Exclusion Criteria:

1. Inability to cooperate
2. Inability to speak and understand Danish
3. Allergy to any drugs used in the study
4. Drug or alcohol abuse
5. Pregnancy or nursing
6. Opioid abusers