Popliteal SNB:Evaluation of Block Dynamics After Subparaneural Injection Below CPN & TN

  • End date
    Jan 3, 2022
  • participants needed
  • sponsor
    Chinese University of Hong Kong
Updated on 3 February 2021


This study aims to assess the effect of twin subparaneural injection into individual paraneural sheaths of Common Peroneal Nerve (CPN) and Tibial Nerve (TN) below their point of divergence from the sciatic nerve on the sensory motor blockade after Popliteal Sciatic Nerve Block (PSNB) at the popliteal fossa (back of the thigh) for patients requiring lower limb surgeries.


Ultrasound (US) guided Popliteal Sciatic Nerve Block (PSNB) has been routinely used to provide surgical anaesthesia for ankle and foot surgeries, and the introduction of ultrasound (US) guidance has improved the ease and accuracy of performing PSNB. However, the challenge of achieving the optimal 'readiness for surgery' time after the US guided PSNB continues to confront anaesthesiologists. Cumulative evidence indicates that a subparaneural PSNB improves sensory motor block outcome when compared to subepimyseal PSNB where the local anaesthetic is deposited outside the paraneural sheath.

While these are encouraging results, producing sensory motor blockade, i.e. surgical anaesthesia in the area innervated by the sciatic nerve within 30 minutes of local anaesthetic (LA) injection, after a subparaneural PSNB, remains a challenge with the success rate varying from 62-92%. Reasons for this shortcoming, despite LA being deposited in subparaneural space, close to the epineurium of the sciatic nerve, is probably multifactorial as the nerve size, surface area exposed to local anaesthetic, and internal architecture (the connective tissue component) of the sciatic nerve and its branches are all seems to influence block onset time and completeness. It was observed from our clinical practice that distal subparaneural injection (twin halo) into individual paraneural sheaths of common peroneal nerve (CPN) and tibial nerve (TN) below the point of divergence at the popliteal fossa demonstrated a faster sensory motor blockade after PSNB. Therefore, this study aims to assess the effect of twin subparaneural injection into individual paraneural sheaths of CPN and TN below their point of divergence from the sciatic nerve on the sensory motor blockade after PSNB at the popliteal fossa.

Condition Musculoskeletal Diseases or Conditions
Treatment Popliteal Sciatic nerve block
Clinical Study IdentifierNCT04506879
SponsorChinese University of Hong Kong
Last Modified on3 February 2021


Yes No Not Sure

Inclusion Criteria

American Society of Anesthesiologists (ASA) physical status I-III scheduled to undergo elective foot and/or ankle surgery under regional anesthesia

Exclusion Criteria

Patient refusal, ASA physical status > , pregnancy, neuromuscular disorder, prior surgery in the popliteal fossa, coagulopathy, allergy to local anaesthetic drugs, and skin infection at the site of needle insertion
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