Methylmethacrylate plasma levels during total hip arthroplasty

Area of Science:

• Biomaterials Science
• Orthopedic Surgery
• Pharmacokinetics

Background:

• Methylmethacrylate (MMA) is a key component in bone cement used in orthopedic procedures like total hip arthroplasty.
• Understanding MMA pharmacokinetics is crucial for assessing patient safety and potential systemic effects following cement implantation.

Purpose of the Study:

• To quantify plasma concentrations of MMA after acetabular and femoral cement implantation during total hip arthroplasty.
• To determine the transpulmonary clearance and elimination half-life of MMA.

Main Methods:

• Blood samples were collected from pulmonary and radial artery catheters in 11 patients undergoing total hip arthroplasty.
• MMA concentrations were measured sequentially after acetabular and femoral cement placement.
• Analysis included peak concentrations, biexponential decay modeling, and calculation of area under the curve (AUC) for pulmonary and radial plasma samples.

Main Results:

• Peak MMA concentrations were significantly higher after acetabular (5.0 ± 1.3 µg/ml) compared to femoral (1.9 ± 0.6 µg/ml) cement implantation.
• MMA plasma levels decreased following a biexponential decay pattern with a short initial half-life (0.3 ± 0.1 min) and a terminal half-life (3 ± 0.7 min).
• Approximately 55.1 ± 7.8% of MMA was cleared during transpulmonary passage, indicating high pulmonary clearance.

Conclusions:

• MMA can be reliably measured in plasma after both acetabular and femoral cement implantation.
• Acetabular cement implantation results in higher peak MMA plasma concentrations than femoral implantation.
• MMA exhibits a short elimination half-life and significant pulmonary clearance, suggesting rapid systemic processing.