| IPACK | LIA | Femoral Nerve Block | Adductor Canal block | Sciatic Nerve Block |
Usual volume of LA (mls) | 15 | 150 | 10 - 15 | 10 - 20 | 10 - 25 |
Nerves covered | Terminal sensory branches of obturator, CPN and tibial nerves | Local & systemic effects | Femoral nerve | Saphenous nerve | Posterior Tibial nerve at popliteal fossa |
Advantages | Safer blocks than central neuraxial blocks especially in patients with coagulopathy or patients on antiplatelet agents. | ||||
| 1) Localised to periarticular region with sparing of vastus muscles; 2) Minimal weakness thus facilitates early rehabilitation; 3) Relatively easy to perform with lower risk of nerve injury; 4) Potential of covering saphenous nerve. | 1) Performed by surgeon and thus less concern of graft infection; 2) Studies have shown that it works as well as Femoral nerve block; 3) Do not require additional ultrasound machine/trained anaesthetist. | 1) Simple and superficial block that can be performed by most anaesthetist; 2) Proven to have opioid sparing and pain scores in knee procedures [2] . | 1) Simple and superficial block that can be performed by most anaesthetists; 2) Avoids blockade of the vastus lateralis and vastus intermedius with less impairment of hip flexion. | 1) Definitive coverage of the posterior knee; 2) Relatively easy to perform. |
Disadvantages | 1) Relatively deep block compared to the other peripheral nerve blocks; 2) LA spread may affect sciatic nerve with potential of motor blockade; 3) Performed near surgical site hence risk of surgical site contamination; 4) New technique with few studies; 5) Few anaesthetists performs the technique; 6) Ideal approach and volume yet to be determined. | 1) Large volume required with risk of LA toxicity; 2) Variability in technique, volume and concoction by various surgeons; 3) Not pre-emptive and hence risk of wind up phenomenon. | 1) Results in motor blockade with risk of fall and delayed rehabilitation; 2) Has not been found to be more advantageous than multimodal analgesia [2] ; 3) Does not cover posterior aspect of the knee. | 1) Blocked performed at site of tourniquet may increase the risk of nerve injury (direct pressure, LA axonal toxicity and needle penetration); 2) May still block the branches to the Vastus medial is if large volume is given; 3) The Adductor canal or sub Sartorius definition is still controversial. | 1)Foot drop may occur if the common peroneal nerve is blocked; 2) May delay rehabilitation and discharge; 3) Does not cover anterior aspect of the knee. |