This is a randomized, observer-masked, controlled study. Subjects will be patients undergoing bilateral total knee arthroplasty (TKA). One side (left or right) will be randomized to one of two treatment groups: a postoperative ropivacaine concentration of 0.1% or 0.4%. The contralateral side will receive the other possible ropivacaine concentration of 0.1% or 0.4%. The basal rate and patient-controlled bolus volume will depend upon the treatment group, but the total dose of local anesthetic is the same for each. For the duration of the study, all patients will receive the current usual and customary analgesics for bilateral TKA patients. All patients will receive a ropivacaine perineural infusions initiated in the operating room and continued until at least the afternoon of postoperative day (POD) 2, as well as oral acetaminophen, a sustained-release oral opioid; and celecoxib. Rescue opioid and route of administration will be determined by pain severity using a Numeric Rating Scale of 0-10, with 0 equal to no pain and 10 being the worst imaginable pain.
The investigators propose to test the null hypothesis that differing concentrations of ropivacaine (0.1% vs. 0.4%) at an equal total dose has no impact on quadriceps muscle strength during a continuous femoral nerve block following total knee arthroplasty (TKA). These results will help define the optimal concentration of local anesthetic used for continuous peripheral nerve blocks.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
48
Patients will be randomized to one of two groups: Ropivicaine 0.1% infusion on the right leg and Ropivicaine 0.4% infusion on the left leg, or Ropivicaine 0.4% infusion on the right leg and Ropiviciane 0.1% infusion on the left leg for treatment of postoperative pain following bilateral TKA. Both groups will receive the same total dose of medication and will have the infusion for the two days following surgery.
The Cleveland Clinic, Main Campus
Cleveland, Ohio, United States
Quadriceps Femoris Muscle Strength Maximum Voluntary Isometric Contraction (MVIC)
A device was used called a dynamometer to measure the force during maximum voluntary isometric contraction. The dynamometer was placed on ipsilateral anterior tibia perpendicular to the tibial crest, just proximal to the medial malleolus. Subjects were asked to take 2 seconds to come to maximum effort contracting the quadriceps, maintain this effort for 5 seconds, and then relax.
Time frame: morning of postoperative day 2
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