Single-injection Modified 4 in 1 Block as Postoperative Analgesia in Total Knee Arthroplasty

Patients suffer from moderate to severe pain after TKA. Patients are asked to begin functional exercise as early as possible after surgery, and that requires adequate control of postoperative pain. Regional anesthesia divides into non-motor sparing peripheral nerve blocks as femoral n. block and sciatic n. block and motor sparing peripheral nerve block as adductor canal block and IPACK but these blocks have many drawbacks.

So new studies found that a modified 4 in-1 block blocks all these nerves and produces adequate analgesia without sparing areas.

Total knee arthroplasty (TKA) is regarded as the most effective method to reduce knee pain and improve knee function in patients with advanced knee osteoarthritis. Postoperative pain is an unpleasant experience for TKA and this pain might greatly influence patients' early rehabilitation.

Almost 60% of patients suffer moderate to severe pain after TKA and 25% of them could even develop related complications, such as longer hospitalization stays, unanticipated hospital admissions, readmissions, etc.

With the development of enhanced recovery after surgery, patients are asked to begin exercise as early as possible after surgery, and that requires adequate control of postoperative pain.

Multimodal systemic analgesia plays an essential role in controlling postoperative pain after TKA by controlling the inflammatory process, dealing with the neuropathic component of pain, and thus reducing the severity of pain.

Multimodal analgesia includes more than one pain-control modality (systemic analgesia and regional anaesthesia). Systemic analgesia includes acetaminophen, nonsteroidal anti-inflammatory drugs, steroids and opioids. Regional anaesthesia includes epidural analgesia, femoral n. block, adductor canal block, sciatic n. block, IPACK, etc. Regional anaesthesia divides into non-motor sparing peripheral nerve blocks as femoral n. block and sciatic n. block and motor sparing peripheral nerve block as adductor canal block and IPACK.

But these blocks have many drawbacks. Femoral n. block is associated with quadriceps muscle weakness leading to delay in patient's mobility. Sciatic n. block also causes foot drop. The Adductor canal block does not cover the skin on the back of the knee. Surgeons refuse IPACK because of diffusion of local anaesthetics disturbs the anatomy of the surgical field.

The Modified 4 in 1 block technique aims to block four nerves (saphenous nerve, obturator nerve, nerve to vastus medialis and sciatic nerve) through a single injection point by spreading up to the adductor canal in midthigh and below to the popliteal fossa. The investigator will conduct this randomized clinical trial to evaluate the quality of postoperative analgesia produced by a single injection modified 4 in 1 block and midsartorius adductor canal block with regard to total analgesic consumption in the first 24 hours postoperatively

Eligibility Criteria:
Inclusion Criteria:

* Body mass index (BMI) of 19-30 kg/m2
* American Society of Anesthesiologists (ASA) functional status of I-III

Exclusion Criteria:

* Drug hypersensitivity
* coagulopathy
* infection at the site of injection
* Traumatic arthirits