Pain associated with hip surgery -a significant problem-Complications, morbidities, and low levels of patient satisfaction.Two blocks that have recently become popular for hip analgesia include pericapsular nerve group (PENG) block and SIFI block.There is paucity in literature regarding these blocks and to which one is more efficacious.

We hypothesised that SIFI block would provide better analgesia without significant quadriceps muscle weakness when compared with the PENG block following THA.

The study will be carried out in accordance with the ethical principles of the Declaration of Helsinki, 2013. Its procedure will be explained to each patient, and a written and informed consent will be taken for participation in this study and for the use of the patient data for educational and research purposes. The consultant doing the pre-anaesthetic check-up will carry out a consecutive sampling of all eligible participants and enroll them into the study. Randomisation will be done by an independent statistician using software for block randomisation techniques of varying block sizes (3–5). Allocation concealment will be done using serially numbered, opaque, sealed envelopes (SNOSE technique). The sealed envelope will be opened by a consultant who is not part of the study once the patient  reaches the pre-medication room, thus assigning the participant to the intervention. This assigned consultant then performs the block in the block room. All observations will be done in the operating room and PACU  by the investigator  who is unaware of the regional block performed.  All the participants will remain blinded to the block administered.

NRS score will be explained to the patients at the time of pre-operative assessment.Pre-procedure pain will be  assessed during rest as well as on movement (15° passive elevation) of the affected limb and recorded on numeric pain rating scale (NRS) [0 = no pain; 10 = worst imaginable pain].

The blocks will be performed in supine position following sterile techniques. Both the blocks will be performed as per the standard USguided techniques using 30 ml 0.2 % ropivacaine with 4mg dexamethasone.

After the block, patient  will be shifted to the operating room and will be continuously monitored with non-invasive blood pressure every 5 minutes, continuous ECG and pulse oximetry and for signs of local anaesthetic toxicity for 30 minutes. Thirty minutes after the blocks, analgesia will be measured by NRS at rest and on passive limb elevation. If any patient had NRS >5, intravenous (IV) fentanyl 20 µg will be given every 5 minutes till NRS score becomes 3, and then, they will be allowed for sitting position for SA.NRS score will be explained to the patients at the time of pre-operative assessment.Pre-procedure pain will be  assessed during rest as well as on movement (15° passive elevation) of the affected limb and recorded on numeric pain rating scale (NRS) [0 = no pain; 10 = worst imaginable pain].

The blocks will be performed in supine position following sterile techniques. Both the blocks will be performed as per the standard USguided techniques using 30 ml 0.2 % ropivacaine with 4mg dexamethasone.

After the block, patient  will be shifted to the operating room and will be continuously monitored with non-invasive blood pressure every 5 minutes, continuous ECG and pulse oximetry and for signs of local anaesthetic toxicity for 30 minutes. Thirty minutes after the blocks, analgesia will be measured by NRS at rest and on passive limb elevation. If any patient had NRS >5, intravenous (IV) fentanyl 20 µg will be given every 5 minutes till NRS score becomes 3, and then, they will be allowed for sitting position for SA.