The aim of this prospective dose finding study is to estimate the minimal effective volume (ED95) for lidocaine 1.0% for filling the adductor canal when placing an adductor canal block. We will apply the Continual Reassessment Method (CRM) for estimating the ED95 and use an MRI scan to evaluate the main objective and ensure spread to the distal part of the adductor canal.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
40
US-guided adductor canal block
Aleris-Hamlet Hospitals Copenhagen
Søborg, Denmark
To estimate the ED 95 for the volume needed to fill the adductor canal distally.
This will be evaluated as a binary outcome using MRI; where the adductor canal is considered to be filled if the lidocaine injectate can be identified inside the canal in the first slice distally to the insertion of the adductor longus muscle on femur.
Time frame: MRI performed 15 minutes post block
To investigate the effect of volume on proximal spread to the femoral triangle
Evaluated as a binary outcome using MRI
Time frame: MRI performed 15 minutes post block
Quadriceps muscle strength
To investigate the effect of volume on quadriceps muscle strength, assessed as maximum voluntary isometric contraction (MVIC) and evaluated as a binary outcome (reduction by more or less than 25%).
Time frame: 1 hour post block
Pin prick test
To investigate the effect of volume on sensory block assessed by pin-prick in the saphenous innervation area and in the popliteal fossa.
Time frame: 1 hour post block
Temperature discrimination test
To investigate the effect of volume on sensory block assessed by cold sensation using alchohol swabs, in the saphenous innervation area and in the popliteal fossa.
Time frame: 1 hour post block
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