ESRA19-0383 Case study: genicular nerve blocks – a novel approach to regional anaesthesia for knee surgery

Background and aims

Regional anaesthesia techniques for knee surgery can pose certain undesirable side effects, such as motor blockade in femoral nerve blockade resulting in difficulties in early mobilisation. Block-sparing of the lateral aspect of the knee as with adductor canal nerve blockade can occur. This case report describes an alternative method of providing regional anaesthesia post knee surgery.

Methods

An 18-year-old male presented for arthroscopic cruciate ligament repair. Using a high frequency linear ultrasound probe in the coronal plane the superolateral genicular nerve (SLGN) and superomedial genicular nerve (SMGN) were identified just proximal to lateral and medial femoral epicondyles, position was confirmed by Doppler identification of the corresponding vessels. A 22G 50mm ultrasound-visible stimulation needle was introduced in an in-plane view and 7 mls of 0.75% Ropivacaine was injected after negative aspiration beside each neuro-vascular bundle. There was no evidence of paraesthesia or pain post block. The patient proceeded with surgery under general anaesthesia.

Results

The patient‘s opioid requirements were minimal during the case and 24 hours post procedure was fully mobile, requiring no further opioids and minimal analgesia. He described no motor deficit.

Conclusions

Genicular nerve isolation has been used to diagnose and treat chronic knee pain. Regional anaesthesia techniques such as adductor canal nerve blocks have been used as motor-sparing techniques but may lead to incomplete blockade and therefore inadequate analgesia and unwanted muscle blockade. SLGN, SMGN and to a lesser extent inferomedial genicular nerve blockade has not been previously described in the acute surgical setting for analgesic purposes