Blood methyl methacrylate levels in patients having prosthetic joint replacement

The Bone Cement Hypercoagulation Syndrome: Pathophysiology, Mortality, and Prevention

Since Charnley introduced acrylic cement to seal metallic hip prostheses in the 1950s, reports of perioperative fatal cardiorespiratory and vascular dysfunctions have been published. Studies on humans and animals have shown neurogenic stimulation and substantial local and systemic activation of coagulation are caused by surgical bone marrow damage and chemical cell destruction by toxic monomeric methyl methacrylate from the implanted cement and other tissue-released substances. Venous blood-borne cell fragments and conjugates of activated cells from the surgical site are sequestered and trapped in the pulmonary microcirculation. A substantial hypercoagulation occurs in the lung circulation. Hypercoagulable blood is passed over to the arterial side and may cause vessel obliteration and organ damage. This process may affect the brain, heart, and kidneys and, through the release of vasoactive substances, introduce hemodynamic imbalances that can lead to fatal outcomes in susceptible populations such as elderly patients with hip fractures. The main underlying pathophysiologic processes leading to these occasionally devastating outcomes are a substantial activation of coagulation and cell destruction caused by the toxic substance released by curing bone cement and several vasoactive substances.

Effects of methyl methacrylate on Ca2+ uptake of cardiac sarcoplasmic reticulum

In isolated cardiac sarcoplasmic reticulum (SR) vesicles, methyl methacrylate (2.5-100mM) directly inhibited initial rates of Ca2+ uptake as well as the maximal uptake. Inhibition of SR Ca2+ uptake by methyl methacrylate was concentration-dependent, and the highest concentration of methyl methacrylate (100mM) almost completely inhibited the SR Ca2+ uptake. EC(50) of methyl methacrylate in percent inhibition of SR Ca2+ uptake was 16.1, 31.9, and 53.4mM at pCa 7.0, 6.6, and 6.0, respectively. At low Ca2+ concentrations (0.1-1 microM), SR vesicles treated with 20mM methyl methacrylate showed the decreased Ca2+ uptake rates. However, further increase of Ca2+ concentration to pCa 5.5 abolished the inhibitory effect of methyl methacrylate on SR Ca2+ uptake, showing no difference between the control and the methyl methacrylate-treated SR vesicles. From these results we could conclude that methyl methacrylate exerts a direct inhibition of cardiac SR Ca2+ uptake. This mechanism, at least in part, might contribute to the profound hypotension induced by methyl methacrylate. Supplementation of calcium ion appears to reduce the methyl methacrylate-induced cardiovascular disturbances efficiently.

Methyl methacrylate levels in unwashed salvage blood following unilateral total knee arthroplasty

To evaluate the safety of autologous reinfusion of drain blood in total knee arthroplasty (TKA), eight patients were prospectively evaluated to quantify levels of methyl methacrylate (MMA) monomer in systemic blood, and in their drain blood after unilateral cemented TKA. The systemic blood was analyzed before and after reinfusion of the drain blood. The drain blood was analyzed before reinfusion, and both before and after filtration through a 40-microm filter. A separate study was performed on 10 patients to assess the effect of blood, time, and filtration on MMA levels. Levels of MMA monomer in salvage blood were low enough to allow safe reinfusion. Systemic blood showed no evidence of MMA monomer either before reinfusion of salvage blood or at 5 minutes after reinfusion. Elimination of MMA is dependent on the time that MMA is exposed to blood and is independent of filtration.

Cardiorespiratory and vascular dysfunction related to major reconstructive orthopedic surgery

Major orthopedic reconstructive surgery is highly traumatic and may be associated with serious peri-operative cardiorespiratory and vascular complications which occasionally may be fatal. These complications are commonest in patients receiving cemented hip prostheses following femoral neck fractures. The etiology is multifactorial. Bone traumatization induces activation of the hemostatic system, i.e., thrombin generation, in venous blood draining the operation area. When this activated blood passes the lung, more thrombin is generated and the blood becomes hypercoagulable and causes fibrin-formation in the lung vessels, with trapping of cellular debris. Thrombin has many hormone-like effects beyond its function in the coagulation cascade system. It may increase vein wall permeability and cause constriction of vessels, which increases blood pressure in the lung. In addition, impaction of bone cement to fill bone cavities or to fix prostheses causes additional mechanical trauma and further release of procoagulant substances into venous blood. Further, release of the cytotoxic chemical methyl-methacrylate monomer into venous blood is superimposed on the thrombin-primed hemostatic disturbances in the lung microvasculature. All these effects may finally induce hemodynamic insufficiency, which occasionally may be fatal. To prevent these adverse reactions, thrombin activity should be reduced and impaction of bone cement minimized.

Methylmethacrylate monomer produces direct relaxation of vascular smooth muscle in vitro

Methylmethacrylate bone cement is associated with severe hypotensive reactions during surgery and anesthesia. The purpose of this in vitro study was to determine if methylmethacrylate monomer could produce hypotension by acting directly on vascular smooth muscle. Segments of human saphenous vein or rabbit thoracic aorta were cut into rings. The rings were mounted in isolated tissue chambers in order to measure isometric tension development. Methylmethacrylate monomer (methylmethacrylic acid ester) produced direct relaxation of venous or aortic rings preconstricted with either potassium ion or noradrenaline. The relaxation was concentration-dependent, occurring at concentrations from 10(-3) to 10(-1) M. The relaxation of rabbit aortic rings (preconstricted with noradrenaline) was unaffected by pre-treatment with atropine, propranolol, cimetidine, indomethacin, or methylene blue. Endothelial stripping with Triton X-100, sufficient to completely abolish acetylcholine-induced relaxation, also had little effect on methylmethacrylate-induced relaxation. Methylmethacrylate produced direct relaxation of rabbit aortic rings constricted with either potassium or noradrenaline in calcium-deficient media, and inhibited subsequent calcium-induced constriction. These results suggest that methylmethacrylate monomer may interfere with intracellular and extracellular calcium mobilization and excitation/contraction coupling in vascular smooth muscle. The direct relaxation of venous and arterial smooth muscle produced by methylmethacrylate monomer may contribute in part to the hypotension that can occur when acrylic bone cement is employed during orthopedic procedures.

Pulmonary function during and after total hip replacement. Findings in patients who have insertion of a femoral component with and without cement

Eleven patients who had a femoral component inserted with cement and twenty-three who had a femoral component inserted without cement were studied prospectively for changes in the pulmonary shunt associated with total hip replacement. The levels of oxygen in the arterial blood and the platelet counts were measured preoperatively and each morning for three days after the arthroplasty. Levels of oxygen in the arterial blood were determined intraoperatively, once before and once after the femoral component was inserted. Intraoperative shunt values increased 28 per cent when a femoral component was inserted with cement (p < 0.05), but they did not change when cement was not used. The average postoperative shunt values were higher than the average preoperative shunt values for both groups of patients, but only the values on the second postoperative day after a procedure with cement were significantly higher (p < 0.05). The ability of the patient to tolerate an increase in pulmonary shunt should be assessed when the femoral component is to be cemented during total hip replacement.

The biologic responses to orthopedic implants and their wear debris

The use of artificial materials in the treatment of orthopaedic conditions, most notably arthritis, over the past few decades has been increasing dramatically. Such use makes an understanding of the tissue responses to the various materials necessary to determine their effectiveness and acceptability. This review concentrates on the studies of the biological responses to the materials that are used mainly in joint replacements and fixation of fractures. In-vivo and in-vitro experimental studies of various metals, polymers and ceramics and their constituents are first presented with discussions regarding their clinical importance. Studies of clinically successful implants are then presented to illustrate the expected morphological features of incorporation and acceptance by the host tissues. The local and systemic effects complicating the use of the implanted materials as well as the failure of the implant are then presented.

Blood levels and half-life of methylmethacrylate after tourniquet release during knee arthroplasty

The blood levels and the half-life of monomeric methylmethacrylate after tourniquet release were studied in nine patients with osteoarthrosis or rheumatoid arthritis of the knee joint, treated with the Townley prosthesis under spinal anesthesia. Several ventricular extrasystoles were monitored in one patient with high blood levels of monomeric methylmethacrylate (119.80 micrograms/ml). The blood levels of monomeric methylmethacrylate ranged between 0.10 and 1.44 microgram/ml in the rest of the patients. The half-life of monomeric methylmethacrylate in vivo was 47-55 min.

Methylmethacrylate blood levels in patients with femoral neck fracture

The blood levels of monomeric methylmethacrylate were measured in 20 patients with fracture of the femoral neck, treated with a Thompson prosthesis under spinal anesthesia. Monomeric methylmethacrylate was detected in the blood stream in all patients; the maximum levels (mean 6.44 micrograms/ml, range 0.05-31.89 micrograms/ml) were measured 30 s after insertion of the Thompson prosthesis. A moderate drop in systolic blood pressure and a marked reduction of arterial oxygen tension was noted after cementation and insertion of the prosthesis; the mean maximum drops were 10.1 mm Hg (range 0-32 mm Hg) and 6.1 mm Hg (range 0-13.5 mm Hg) No dose-dependent correlation could be established between the levels of monomeric methylmethacrylate and the drop in arterial blood pressure or arterial oxygen tension.

Depressive effects of acrylic cement components on bone metabolism. Isotope release and phosphatase production studied in vitro

In vitro methyl methacrylate bone cement components were found to depress the release of radioactive calcium and proline as well as the activity of both alkaline and acid phosphatases. These effects were dose dependent and reached levels observed for dead bone. These observations may reflect part of the pathogenesis of loosening of joint replacements involving the use of bone cement.

Metabolism of methyl methacrylate: evidence for metabolism by the valine pathway of catabolism in rat and in man

1. Evidence to support the suggestion that methyl methacrylate is metabolized by the normal pathway of valine catabolism has been obtained by the administration of methyl [Me-14C]methacrylate to rats. 2. Of the administered dose, 80% was respired as 14CO2 as predicted, and methylmalonic acid, specifically labelled with 14C in a manner consistent with the proposed pathway of metabolism, was excreted (0.22%) dose). 3. Following administration of sodium [Me-2H3]methacrylate to a human subject, [Me-2H3]methylmalonic acid was detected in the urine by g.l.c.-mass spectrometry.

A dual mechanism for intestinal motor effects of methyl methacrylate vapor

The influence of methyl methacrylate (MMA) vapor on the motor activity of the isolated guinea pig ileum is summarized in this report. MMA vapor was delivered to innervated and denervated strips via the tissue bath air supply at a concentration of 755 +/- 38 ppm. Innervated strips usually showed spontaneous motor activities (sma) which developed shortly after the muscle was mounted. None of the denervated strips exhibited sma. Upon exposure to MMA vapor, there was a rapid and significant decrease in sma and in the contractile responses to electric field stimulation and 0.01 mg acetylcholine administration. Denervated strips demonstrated a similar reduction in response magnitude to electric field and drug stimulation but required a longer time period. The persistence of the MMA-induced inhibitory response of the denervated strips indicates that the inhibitory effect is partly due to a direct action of the agent upon the contractile mechanism of the small intestine.

New clinico-pathophysiological studies on the bone cement implantation syndrome

Implantation of endoprostheses with bone cement is followed by alterations of the circulation. Intoxication, caused by the monomer of bone cement or pulmonary embolism by intramedullary contents constitute the two mostly accepted pathophysiological hypotheses. Because of the lack of pulmonary and circulatory physiological data a clinical decision concerning the value of the hypotheses was not possible until now. Hip prosthesis implantation was analyzed in 15 patients by measuring equipment controlled by an on-line-computer. The device allowed a high rate of data retrieval. The bone cement implantation syndrome reveals itself as cardiorespiratory sequelae of a disseminated pulmonary embolism which is originating in intramedullary contents, squeezed intravasal. Usual prophylactic methods are revisited.

Methylmethacrylate hypersensitivity in a patient with cemented endoprosthesis. A case report

A case of methylmethacrylate monomer hypersensitivity in a 76-year-old patient with a cemented endoprosthesis is reported. The accuracy of the method for preoperative testing of a patient's sensitivity is discussed.

Metal sensitivity in patients with joint replacement arthroplasties

A high incidence of unexpected metal sensitivity was found in patients with metal-to-metal (McKee) hip arthroplasties. Patients with metal-to-plastic (Charnley) prostheses had no greater incidence of metal sensitivity than a control group awaiting operation. If metal sensitivity does occur loosening of the prosthesis may be a complication.