Plasma Ropivacaine Concentrations Following Local Infiltration Analgesia in Total Knee Arthroplasty: A Pharmacokinetic Study to Determine Safety Following Fixed-Dose Administration.

BACKGROUND AND OBJECTIVES: The primary aim of this study was to examine the pharmacokinetics of ropivacaine in patients undergoing elective total knee arthroplasty with local infiltration analgesia as the primary analgesic method. We also sought to determine the incidence of biochemical toxicity through measurement of plasma ropivacaine concentrations over the first 24 hours postoperatively. METHODS: This was a prospective, observational study of 15 patients undergoing elective total knee arthroplasty. Local infiltration analgesia was administered by standard technique with 300 mg ropivacaine and epinephrine 5 µg/mL. Total ropivacaine concentrations were taken at specified time intervals in the 24 hours after tourniquet release and analyzed by liquid chromatography-mass spectrometry. RESULTS: Fifteen patients were enrolled into the study. The median peak ropivacaine concentration was 0.57 µg/mL, with a range of 0.32 to 0.88 µg/mL, and occurred between 6 and 24 hours. Age (P = 0.04), weight (P = 0.04), creatinine (P = 0.02), and female sex (P = 0.03) were important predictors of peak concentration. Age (P = 0.02), female sex (P = 0.01), and baseline α1 acid glycoprotein concentrations (P = 0.03) were important predictors for the area under the curve from a ropivacaine concentration versus time plot. CONCLUSIONS: The peak total ropivacaine concentration was below quoted toxic concentrations (2.2 µg/mL) in all patients. This peak occurred later than has previously been described in those undergoing neuraxial or peripheral nerve block, occurring between 6 and 24 hours. The influence of age, weight, and renal function on systemic ropivacaine concentration should be considered when planning local infiltration analgesia. Female sex is a factor that has not previously been associated with peak ropivacaine concentrations.

Open Ankle Dislocation Without Fractures With Tibialis Posterior Tendon Interposition Through the Interosseous Space.

Open ankle dislocations without fracture are rare injuries. Dislocation or interposition of adjacent tendons are a rare associated feature of ankle fracture-dislocation. We report an extremely unusual case of open ankle dislocation without fracture with concurrent tibialis posterior tendon interposition through the interosseous space that was detected incidentally on computed tomography. We highlight the clinical, radiologic, and intraoperative features to avoid missing similar diagnoses.

Open reduction and intramedullary stabilisation of subtrochanteric femur fractures: A retrospective study of 56 cases.

Subtrochanteric femur fractures commonly present with predictable displacement because of the deforming muscle forces acting upon the proximal femur. For this reason, successful closed reduction and femoral nailing can be a technically demanding procedure. Open reduction prior to nail placement has been advocated to improve and maintain anatomic fracture alignment. The purpose of this study was to evaluate the results of patients with closed subtrochanteric femur fractures treated with open reduction and a reamed antegrade statically locked intramedullary nail. An initial query of our database identified 154 patients who had sustained a subtrochanteric femur fracture over the defined study period. Ninety-six patients had adequate radiographic and clinical follow-up. Fifty-six (58%) patients were treated with open reduction and nail placement. There were no wound complications or infections and all patients went on to successful osseous union. There was no loss of reduction and a final coronal and sagittal plane deformity of <5 degrees in 55 of 56 (98%) patients. Open reduction of closed subtrochanteric femur fractures followed by intramedullary nailing leads to high union rates with rare complications.