Efficacy of Hematoma Block on Postoperative Pain After Femoral Intramedullary Rodding: A Randomized Trial

Femur Fracture

Femoral Intramedullary Rod, Hematoma Block

The purpose of this study is to evaluate the efficacy of an intra-operative, post-fixation fracture hematoma block compared to saline control on postoperative pain control in patients with acute femoral shaft fractures. Our primary outcome measure is visual analog scale (VAS) pain scores which are recorded at regular intervals.

This blinded, randomized control trial is being performed at the University of Cincinnati Medical Center. Patients will be randomly assigned to one of two treatment groups: Group One will be comprised of patients treated with fracture site injection containing 20 mL of 0.5% ropivacaine with an 18-gauge needle (150 mm length), Group Two will be comprised of patients treated with fracture site injection containing 20ml of normal saline. The injection will be administered by the orthopaedic trauma team after the insertion of the final intramedullary implant and skin closure prior to final surgical dressing application. The injection will be performed in a standard fashion with aspiration of hematoma followed by the injection. All postoperative management will be per standard of care. The size of the hematoma will have no effect on the procedure. When a hematoma block is utilized in the care of orthopaedic trauma patients, its aim is to infiltrate the anesthetic to the fracture edges and injured soft tissue to allow for pain control and fracture manipulation without additional sedation. Aspiration of the hematoma tells the clinician that the tip of the needle is near the fracture site and not in a neurovascular structure. The maximal single dose of ropivacaine without vasoconstrictor is 2-3 mg/kg.9 0.5% ropivacaine has 5 mg/mL of ropivacaine. 20 mL of 0.5% ropivacaine has 100 mg of ropivacaine. 100 mg of ropivacaine can be toxic to a patient less than 33-50 kg or 73-110 lb. If a patient weighs less than 110 lb, the ropivacaine dose will be scaled down below 2 mg/kg. Regional anesthesia including nerve blocks is not routinely used in the setting of traumatic femoral shaft fractures. A nerve block would compromise the patient's neurologic examination in the immediate postoperative period. Randomization will be performed via Microsoft Excel to generate random numbers. Allocation will be concealed and revealed to the surgical team in the hour prior to the procedure. The patients and the nursing staff who assess postoperative pain will be blinded to the treatment allocation. An a priori power analysis was performed to determine the sample size for the primary outcome measure. Prior literature has indicated that a difference of 1.3 on a VAS is clinically significant.5 Therefore, it was determined that a total of 44 patients were necessary per group to detect a 1.5-point difference on the VAS (power = 80%, p = 0.05).

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