Postoperative Knee Strength Following Total Knee Replacement: A Double-Blinded Randomized Comparison Study

Not Applicable

Completed

Brief Summary: Major surgery involving the knee is often associated with severe postoperative pain. Postoperative pain control remains a significant contributor to delayed recovery and length of hospital stay. Approaches to minimize postoperative pain after surgery are a matter of major concern due to the need for early mobilization, a crucial factor in good postoperative rehabilitation. Femoral nerve blocks by either continuous infusion or single injection of anesthetics provide an effective method for analgesia while minimizing the need for systemic opioid therapy, reducing the opioid induced side effects, and facilitating early ambulation. Administration of fentanyl has shown to be a highly effective method to control pain after Total Knee Replacement (TKR). The investigators hypothesize that fentanyl infusions will result in greater post-operative strength in the operative knee.

Detailed Description: All subjects scheduled to receive a unilateral, primary total knee replacement were evaluated for eligibility in the preoperative anesthesia center. Adults, older than 18 years of age, ASA I-III were included in the study. Subjects who were either pregnant, on anticoagulant therapy, allergic to opioids, local anesthetics, chronic pain patients, history of traumatic lower extremity injury, or had a body mass index of greater than 35 kg/m2 were excluded from the study.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

Arm && Interventions

Group	Intervention	Description
Femoral Nerve Ropivacaine	Ropivacaine	Ropivacaine 0.1% continuously delivered through a femoral nerve sheath catheter for 24 hours post-total knee replacement. All study drugs were continuously infused for a 24 hour period at a basal rate of 10ml/hour starting from the time the patient entered the post anesthesia care unit (PACU).
Femoral Nerve Fentanyl	Fentanyl	Fentanyl 3 µg/ml delivered continuously through a femoral nerve sheath catheter for 24 hours post-total knee replacement. All study drugs were continuously infused for a 24 hour period at a basal rate of 10ml/hour starting from the time the patient entered the post anesthesia care unit (PACU).
Intravenous Fentanyl with placebo	Fentanyl	Control group which received 0.9% normal saline delivered through a femoral nerve sheath catheter in addition to a continuous intravenous infusion of fentanyl 3 µg/ml via a PCA pump. All study drugs were continuously infused for a 24 hour period at a basal rate of 10ml/hour starting from the time the patient entered the post anesthesia care unit (PACU).

Primary Outcome Measures

Name	Time	Method
Comparison of Postoperative Strength (Extension)	24 hours post-surgery	To assess extension force postoperatively to discern differences in muscle strength retention between continuous femoral nerve sheath catheter administration of fentanyl or Ropivacaine or a continuous IV infusion of fentanyl.

Secondary Outcome Measures

Name	Time	Method
VAS Scores and Postoperative Supplemental Morphine Consumption	24 hours post-surgery	Secondary Objective * To determine the amount of required supplemental analgesia during the postoperative period. * To determine postoperative analgesia using a Visual Analog Scale (VAS) 0 - 10 centimeter line.
Serum Fentanyl Levels	24 hours post-surgery	To identify a difference in serum fentanyl levels among the groups.