JBJS | Comparison of Fixation of the Femoral Component without Cement and Fixation with Use of a Bone-Vacuum Cementing Technique for the Prevention of Fat Embolism During Total Hip Arthroplasty. A Prospective, Randomized Clinical Trial*

The Journal of Bone & Joint Surgery, Volume 81, Issue 6

Articles | June 01, 1999

Comparison of Fixation of the Femoral Component without Cement and Fixation with Use of a Bone-Vacuum Cementing Technique for the Prevention of Fat Embolism During Total Hip Arthroplasty. A Prospective, Randomized Clinical Trial*

ROCCO PAOLO PITTO, M.D.†; MATTHIAS KOESSLER, M.D.†; JOERN W. KUEHLE, M.D.†, ERLANGEN, GERMANY

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Investigation performed at the Department of Orthopaedic Surgery and the Department of Intensive Care and Anesthesiology, University of Erlangen-Nuremberg, Erlangen

The Journal of Bone & Joint Surgery. 1999; 81:831-43

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Abstract

Background: Acute hypotension, hypoxemia, cardiac arrest, and sudden death are well recognized complications during total hip arthroplasty, and they have been attributed to embolization of fat and bone marrow. An increase in intramedullary pressure in the femur is the most important pathogenic factor for the development of embolic events. Intravasation of fat, bone marrow, and bone debris during the implantation of a femoral component, and the embolization of these elements through the venous system located along the linea aspera and through the metaphyseal vessels, have been demonstrated experimentally and clinically. The purpose of the present study was to compare the effects of fixation of the femoral component without cement with those of fixation with a bone-vacuum cementing technique on the severity of embolic phenomena and cardiopulmonary impairment during total hip arthroplasty. Fixation with a conventional cementing technique was also evaluated as a control.Methods: Sixty patients (sixty hips) were entered into a prospective, randomized clinical trial. The patients were assigned to one of three groups. Group 1 consisted of twenty patients who had the femoral component inserted without cement, Group 2 comprised twenty patients who had the component inserted with a conventional cementing technique, and Group 3 included twenty patients who had fixation with the so-called bone-vacuum cementing technique. In the hips in Group 3, a suction of -800 millibars (-80,000 pascals) was applied to a proximal drainage cannula placed along the linea aspera and a distal drainage cannula placed in the diaphysis in order to produce a vacuum in the medullary cavity of the femur during the application of cement and the insertion of the stem. Transesophageal echocardiography and hemodynamic and blood-gas analysis were performed during the operation.Results: Severe embolic events (defined as a cascade of fine echogenic particles of less than five millimeters in diameter) were observed in seventeen (85 percent) of the twenty patients during insertion of the stem with use of a conventional cementing technique but in none of the patients who had the stem inserted without cement (p < 0.05). Insertion of the femoral component with the bone-vacuum cementing technique prevented embolic phenomena in all but one patient (5 percent). Arterial oxygen saturation decreased significantly (p < 0.05) from a mean of 99.5 to 92.9 percent after insertion of the stem with a conventional cementing technique, but only slight changes were observed in the patients who had fixation of the component without cement and in those who were managed with the bone-vacuum cementing technique. Intraoperative pulmonary shunt values increased a mean of 24 percent (p < 0.05) when the femoral component was inserted with a conventional cementing technique, but with the numbers available we did not detect a significant change in those values when the component was fixed without cement or when it was inserted with use of the bone-vacuum cementing technique.Conclusions: The present study showed that severe embolic events and intraoperative pulmonary impairment are common when a femoral component is fixed with use of a conventional cementing technique. The results clearly demonstrated a low risk of embolism during total hip arthroplasty when the femoral component was fixed without cement and when it was fixed with the bone-vacuum cementing technique. The ability of a patient to withstand an embolic event should be considered before fixation of the femoral component with use of a conventional cementing technique is planned.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Embolization of fat and bone-marrow elements during total hip arthroplasty is a phenomenon directly related to the operation that may have important cardiorespiratory and neurological effects^{4,6,12,17,19,35}. Woo et al.³⁹ reviewed several studies on total hip arthroplasty that included information about severe intraoperative complications. In those series, which ranged in size from 400 to 2012 procedures, they found that 0.6 to 10 percent of the patients had cardiac arrest and 0.02 to 0.5 percent of the patients died. In a series of 38,488 total hip arthroplasties, Parvizi et al.²² reported that twenty-three patients (0.06 percent) died intraoperatively.

Embolic events are believed to be directly related to increased intramedullary pressure caused by operative manipulation of the bone and thus are, at least partially, under the control of the operating surgeon. In fact, experimental and clinical evidence supports the theory that the most important pathogenic factor for the development of embolism is an increase in intramedullary pressure caused by mechanical compression of the femoral canal during the insertion of the stem^{3,15,16,32,38}.

Orsini et al.²¹, in an experimental study on dogs, found that the quantity of fat emboli and the severity of cardiorespiratory changes observed during total hip arthroplasty with cement were greater than those seen when cement was not used. In a study involving use of transesophageal echocardiography in humans, Christie et al.⁶ showed that insertion of the femoral component with cement caused more severe and more prolonged embolic cascades than did insertion of the component without cement. Ries et al.²⁶ reported that intraoperative pulmonary shunt values increased significantly (28 percent, p < 0.05) when the femoral component was inserted with cement, but the shunt values did not change when the component was inserted without cement. These findings suggest that patients who need a total hip arthroplasty, especially those who have underlying cardiorespiratory disease, may have less morbidity if the femoral component is inserted without cement than if it is inserted with cement.

The purpose of the present prospective, randomized clinical trial was to test the hypothesis that implantation of the femoral component without cement or with use of the bone-vacuum cementing technique substantially reduces the occurrence of intraoperative fat embolism and cardiorespiratory changes compared with that during implantation with a conventional cementing technique.

*Although none of the authors has received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this article, benefits have been or will be received, but are directed solely to a research fund, foundation, educational institution, or other nonprofit organization with which one or more of the authors is associated. Funds were received in total or partial support of the research or clinical study presented in this article. The funding sources were Doktor Robert Pfleger Foundation, Bamberg, Germany.

†Department of Orthopaedic Surgery (R. P. P. and J. W. K.) and Department of Intensive Care and Anesthesiology (M. K.), Friedrich-Alexander University Erlangen-Nuremberg, Waldkrankenhaus, Rathsberger Strasse 57, 91054 Erlangen, Germany. E-mail address for Dr. Pitto: pitto@rzmail.uni-erlangen.de.

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Fig. 1 Drawing showing the position of the proximal drainage cannula that is used in the bone-vacuum cementing technique. The cannula is placed between the greater and lesser trochanters, in the trochanteric fossa, along the projection of the linea aspera. POST. = posterior and ANT. = anterior.

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Fig. 2 Drawing showing the positions of the two 4.5-millimeter-diameter cannulae that are used in the bone-vacuum cementing technique. The intramedullary permeable restrictor is placed at the level of the distal unicortical venting hole, which must be drilled at least two centimeters distal to the expected location of the tip of the stem.

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Figs. 3-A through 3-D: Transesophageal echocardiograms made during total hip arthroplasty, showing the main echogenic patterns. Fig. 3-A: Grade 0. No emboli or small echogenic particles are evident.

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Fig. 3-B Grade 1. A few fine emboli are seen.

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Fig. 3-C Grade 2. A cascade of fine emboli or embolic masses with a diameter as large as five millimeters is evident, and the right atrium is opacified with echogenic material.

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Fig. 3-D Grade 3. Fine emboli are mixed with large embolic masses that have a diameter of more than five millimeters or with serpentine emboli.

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Figs. 4-A and 4-B: Graphs showing the distribution of embolic events observed with transesophageal echocardiography in the three groups of patients. The asterisks indicate that the intensity of the echogenic observations was significantly different from that in the other groups (p < 0.05). Fig. 4-A: Distribution of embolic events during the insertion of the stem. A grade-2 embolism (a cascade of fine emboli) occurred in 85 percent (seventeen) of the patients who had the stem inserted with a conventional cementing technique. A grade-3 embolism (large masses of more than five millimeters in diameter) was not observed during insertion of the stem.

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Fig. 4-B Distribution of embolic events observed a few seconds after the relocation of the hip joint. A grade-3 embolism (large masses of more than five millimeters in diameter) occurred in 50 percent (ten) of the patients who had the stem inserted with a conventional cementing technique.

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Fig. 5 Graph showing the mean intraoperative values (and standard errors of the mean) of oxygen saturation (SaO2) during total hip arthroplasty, when all patients were receiving 100 percent inspired oxygen, in the three groups of patients. The mean oxygen saturation decreased significantly (6.6 percent, p < 0.05) five minutes after insertion of the femoral component (event 4) and remained below the baseline values five minutes after relocation of the hip joint (event 5) for the patients who had insertion with a conventional cementing technique.

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Fig. 6 Graph showing the mean levels (and standard error of the mean) of end tidal carbon dioxide (PetCO2) in the three groups of patients. With a conventional cementing technique, the value decreased significantly (2.4 millimeters of mercury [0.32 kilopascal], p < 0.05) five minutes after insertion of the femoral component (event 4) and five minutes after relocation of the hip joint (event 5). Marked changes were not observed in patients who had insertion without cement or insertion with the bone-vacuum cementing technique.

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Fig. 7 Graph showing the mean perioperative pulmonary shunt values in the three groups of patients. The volumes measured during implantation of the cup (event 2) and preparation of the femur (event 3) were not higher than those during the initial phase of the operation (event 1). With a conventional cementing technique, the mean value five minutes after insertion of the femoral component (event 4) was significantly higher (24 percent, p < 0.05) than the mean intraoperative baseline value. However, the mean value two hours after the end of the operation (event 7) was not markedly higher than the mean value at the start of the operation.

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Fig. 8 Graph showing the mean perioperative pulmonary shunt values and the physical status of the sixty patients assessed according to the criteria of the American Society of Anesthesiologists (ASA)¹. A more pronounced and prolonged increase in the pulmonary shunt values was observed in patients with severe preexisting systemic disease who had a massive embolism during the operation. ASA 1 = a healthy patient, ASA 2 = mild systemic disease, ASA 3 = severe systemic disease that limited activity but was not incapacitating, and ASA 4 = incapacitating systemic disease that was a constant threat to life.

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TABLE I DATA ON THE PATIENTS*

*Group 1 = femoral component inserted without cement, Group 2 = femoral component inserted with conventional cementing technique, and Group 3 = femoral component inserted with the bone-vacuum cementing technique.†The values are given as the mean and the standard deviation.‡Physical status was determined according to the system of the American Society of Anesthesiologists¹. Class 1 = a healthy patient, class 2 = mild systemic disease, class 3 = severe systemic disease that limited activity but was not incapacitating, and class 4 = incapacitating systemic disease that was a constant threat to life.

Parameter	Group 1 (N = 20)	Group 2 (N = 20)	Group 3 (N = 20)
Gender (M/F)	8/12	7/13	9/11
Age† (yrs.)	65 ± 4.2	63 ± 4.5	67 ± 5.7
Weight† (kg)	72 ± 6	69 ± 5	77 ± 4
Height† (cm)	165 ± 21	171 ± 25	163 ± 22
Duration of op.† (mins.)	58 ± 12	71 ± 22	77 ± 16
Estimated blood loss† (ml)	964 ± 477	1105 ± 456	1012 ± 503
Physical status‡ (no. of patients)
Class 1	8	7	10
Class 2	6	7	3
Class 3	6	5	6
Class 4	0	1	1

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TABLE I DATA ON THE PATIENTS*

Parameter	Group 1 (N = 20)	Group 2 (N = 20)	Group 3 (N = 20)
Gender (M/F)	8/12	7/13	9/11
Age† (yrs.)	65 ± 4.2	63 ± 4.5	67 ± 5.7
Weight† (kg)	72 ± 6	69 ± 5	77 ± 4
Height† (cm)	165 ± 21	171 ± 25	163 ± 22
Duration of op.† (mins.)	58 ± 12	71 ± 22	77 ± 16
Estimated blood loss† (ml)	964 ± 477	1105 ± 456	1012 ± 503
Physical status‡ (no. of patients)
Class 1	8	7	10
Class 2	6	7	3
Class 3	6	5	6
Class 4	0	1	1

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TABLE II TRANSATRIAL EMBOLIC EVENTS DURING THE OPERATION*

*Group 1 = femoral component inserted without cement, Group 2 = femoral component inserted with a conventional cementing technique, and Group 3 = femoral component inserted with the bone-vacuum cementing technique. Grade 1 = a few fine emboli, grade 2 = a cascade of fine emboli or embolic masses with a diameter as large as five millimeters, and grade 3 = fine emboli mixed with embolic masses with a diameter of more than five millimeters. †The values are given as the mean and the standard deviation.

Event	Group 1			Group 2			Group 3
Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3
Preparation of femoral canal
No. (percent) of hips	2 (10)	3 (15)		4 (20)	2 (10)
Duration of embolic event† (secs.)	6 ± 2	3 ± 1		5 ± 1.5	4 ± 2
Implantation of stem
No. (percent) of hips	15 (75)			2 (10)	17 (85)		16 (80)	1 (5)
Duration of embolic event† (secs.)	4 ± 3			8 ± 6.5	11 ± 4		7 ± 3	4
Relocation of hip joint
No. (percent) of hips	11 (55)			4 (20)	5 (25)	10 (50)	13 (65)
Duration of embolic event† (secs.)	4 ± 2			5 ± 3.3	4 ± 2.5		4 ± 2

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TABLE II TRANSATRIAL EMBOLIC EVENTS DURING THE OPERATION*

Event	Group 1			Group 2			Group 3
Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3
Preparation of femoral canal
No. (percent) of hips	2 (10)	3 (15)		4 (20)	2 (10)
Duration of embolic event† (secs.)	6 ± 2	3 ± 1		5 ± 1.5	4 ± 2
Implantation of stem
No. (percent) of hips	15 (75)			2 (10)	17 (85)		16 (80)	1 (5)
Duration of embolic event† (secs.)	4 ± 3			8 ± 6.5	11 ± 4		7 ± 3	4
Relocation of hip joint
No. (percent) of hips	11 (55)			4 (20)	5 (25)	10 (50)	13 (65)
Duration of embolic event† (secs.)	4 ± 2			5 ± 3.3	4 ± 2.5		4 ± 2

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TABLE III ARTERIAL BLOOD PRESSURE*

*Group 1 = femoral component inserted without cement, Group 2 = femoral component inserted with a conventional cementing technique, and Group 3 = femoral component inserted with the bone-vacuum cementing technique. The values are given as the mean and the standard deviation in millimeters of mercury, with kilopascals in parentheses. †The difference was significant compared with the other groups (p < 0.05).

	Baseline Value		Value After Insertion of Stem
Diastolic	Systolic	Diastolic	Systolic
Group 1	68 ± 12 (9 ± 1.6)	131 ± 14 (17 ± 1.9)	71 ± 15 (9 ± 2.0)	127 ± 20 (17 ± 2.7)
Group 2	70 ± 16 (9 ± 2.1)	127 ± 9 (17 ± 1.2)	61 ± 13 (8 ± 1.7)	99 ± 18 (13 ± 2.4)†
Group 3	73 ± 13 (10 ± 1.7)	126 ± 12 (17 ± 1.6)	69 ± 9 (9 ± 1.2)	121 ± 16 (16 ± 2.1)

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TABLE III ARTERIAL BLOOD PRESSURE*

*Group 1 = femoral component inserted without cement, Group 2 = femoral component inserted with a conventional cementing technique, and Group 3 = femoral component inserted with the bone-vacuum cementing technique. The values are given as the mean and the standard deviation in millimeters of mercury, with kilopascals in parentheses. †The difference was significant compared with the other groups (p < 0.05).

	Baseline Value		Value After Insertion of Stem
Diastolic	Systolic	Diastolic	Systolic
Group 1	68 ± 12 (9 ± 1.6)	131 ± 14 (17 ± 1.9)	71 ± 15 (9 ± 2.0)	127 ± 20 (17 ± 2.7)
Group 2	70 ± 16 (9 ± 2.1)	127 ± 9 (17 ± 1.2)	61 ± 13 (8 ± 1.7)	99 ± 18 (13 ± 2.4)†
Group 3	73 ± 13 (10 ± 1.7)	126 ± 12 (17 ± 1.6)	69 ± 9 (9 ± 1.2)	121 ± 16 (16 ± 2.1)

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

We performed a prospective study of sixty patients with osteoarthritis of the hip joint who had a total hip arthroplasty with the femoral component inserted with or without cement. The patients were randomly assigned, with use of a computer program (Applicom, Erlangen, Germany), to one of three groups. Twenty patients had the femoral component inserted without cement (Group 1), twenty had the component inserted with a conventional cementing technique (Group 2), and twenty had the component inserted with the bone-vacuum cementing technique (Group 3). The main criteria for exclusion from the study were esophageal disease, metabolic bone disease, and an age of less than fifty-five years or more than seventy-five years. The study was approved by the Investigational Review Committee of the hospital. Particular attention was paid to informing the patients about the advantages and the disadvantages of fixation of the femoral component with and without cement. All patients signed an informed-consent form, and all operations were performed by the senior one of us (R. P. P.). The patient was placed in the supine position, and the hip joint was exposed through the direct lateral approach. A press-fit acetabular component was inserted without cement in fifty-one hips. A reinforcement ring was implanted without cement, and polymethylmethacrylate was used to fix the all-polyethylene cup into the ring, in the remaining nine hips.

In Group 1, the metaphyseal bone was removed and the femoral canal was opened with use of an osteotome. The chipped-tooth broaches (CLS; Sulzer Medica, Baar, Switzerland) that were used to prepare the femoral canal were inserted carefully after suctioning of the medullary contents. A tapered stem (CLS; Sulzer Medica) in the largest size that provided a stable press-fit then was inserted. Neither powered instruments nor pulsatile lavage were used.

In Group 2, the femoral canal was opened with use of an osteotome and the medullary cavity was prepared with chipped-tooth broaches (Osteal, Ceraver, Paris, France) after aspiration of fat and bone marrow. A bone plug was placed into the distal part of the femur, and pulsatile high-volume lavage of the bone surface was performed with normal saline solution. Vacuum-mixed standard-viscosity polymethylmethacrylate (Palacos R; Merck, Darmstadt, Germany) was inserted in an antegrade manner and pressurized with a cement gun (Scientific Development, Munich, Germany) before the insertion of the stem (Osteal, Ceraver). A Teflon (polytetrafluoroethylene) tube was used to vent the intramedullary canal during insertion of the stem.

In Group 3, the femur was prepared with use of special cutting tools coated with a fine, pure diamond surface (Scientific Development). These innovative operative instruments were developed to reduce the production of bone debris as well as to avoid an increase in intramedullary pressure and thus to prevent the risk of embolism of medullary content, which is common when standard broaches are used. A proximal drainage cannula with a diameter of 4.5 millimeters was positioned on the projection of the linea aspera into the cancellous bone of the intertrochanteric region (Fig. 1). Care was taken to avoid intramedullary placement of the twenty-millimeter-long cannula. A distal drainage cannula with a diameter of 4.5 millimeters was placed percutaneously two centimeters distal to the tip of the stem after unicortical predrilling with use of an intramedullary guide (Fig. 2). A permeable methacrylate plug (Scientific Development) was inserted into the femoral canal at the level of the drill-hole and was fixed with the threaded tip of the drainage cannula in order to avoid distal displacement during the application of the cement and the insertion of the stem. The porous structure (a pore size of one to two millimeters) acts as a filter and allows continuous passage of blood and air, but not cement, through the femoral canal. The two cannulae were connected with suction tubes to the vacuum pump (Vacumix; Braun, Melsungen, Germany), which provided suction of -800 millibars (-80,000 pascals). The drainage system was checked thoroughly to make sure that it was functioning adequately. No bleeding of the cancellous bone is visible if the suction system works correctly. The cannulae drained the femoral canal during the application of the cement and the insertion of the stem, which prevented an increase in the intramedullary pressure and promoted the intrusion of the polymethylmethacrylate into the cancellous bone. The bone surface was washed with pulsatile high-volume lavage before application of the same vacuum-mixed standard-viscosity polymethylmethacrylate that was used in Group 2. A cement gun was used to insert the cement in an antegrade manner and to provide pressurization. Finally, an anatomical femoral component (CTS; Scientific Development) was implanted. After the cement had hardened, the drainage cannulae were removed and the distal drill-hole of the diaphysis was filled with small chips of cancellous bone obtained from the autologous femoral head. The same amount of polymethylmethacrylate (eighty grams) was used in the patients in both Group 2 and Group 3. Although the design of the femoral components used in these two groups of patients was different, the total volume of the implants in the available sizes was similar.

The preoperative physical status of the patients was assessed according to the criteria of the American Society of Anesthesiologists¹. Class 1 indicated a healthy patient; class 2, mild systemic disease; class 3, severe systemic disease that limited activity but was not incapacitating; and class 4, incapacitating systemic disease that was a constant threat to life. The clinical data in the admission record and in the evaluation by the anesthesiologist were reviewed. Body plethysmography (Zan, Waldfenster, Germany) was performed one day before the operation in all patients to test pulmonary function. Preoperative assessment with transthoracic echocardiography was carried out only in patients who had known impairment of cardiac function.

General anesthesia was induced with Hypnomidate (propylene glycol) combined with fentanyl, and muscle relaxation was induced with pancuronium. Anesthesia was maintained with one-third to one-half the minimum alveolar concentration of isoflurane or desflurane, depending on the physical status of the patient. All patients had endotracheal intubation and were mechanically ventilated to maintain a constant level of end tidal carbon dioxide. The fractional inspired oxygen concentration was also maintained at a constant level (0.33 percent) during the operative procedure. All patients received 7000 units of heparin subcutaneously twelve hours before the total hip arthroplasty. Lost blood was replaced with predonated autologous blood and with blood obtained by means of intraoperative salvage with use of the Cell Saver (Haemonetics, Braintree, Massachusetts). A central venous line in the right internal jugular vein was used to monitor central venous pressure in patients who had an associated disease (class-3 or 4 physical status, according to the criteria of the American Society of Anesthesiologists¹). The end tidal carbon dioxide level as well as the oxygen saturation was measured continuously. We used the method suggested by Ries et al.²⁶ to derive the pulmonary shunt values (the proportion of the cardiac output that passes through the lungs without participating in gas-exchange).

During the operation, a five-megahertz monoplanar transesophageal echocardiography probe (Hewlett-Packard, Andover, Massachusetts) was inserted to allow visualization of the four chambers of the heart. After a baseline recording had been made, a test for a so-called flow patent foramen ovale was performed in each patient by injecting ten milliliters of agitated saline solution into a peripheral vein and observing the right and left atria. The intraoperative monitoring was continuously videotaped, and the images were analyzed by an observer who was unaware of the method of fixation of the femoral component. The echogenic patterns seen during the operation were considered to be grade 0 when there were no emboli, grade 1 when there were a few fine emboli, grade 2 when there was a cascade of fine emboli or embolic masses with a diameter as large as five millimeters, and grade 3 when there were fine emboli mixed with embolic masses with a diameter of more than five millimeters (Figs. 3-A, 3-B, 3-C and 3-D). The duration of the observed embolic phenomena was measured with use of the chronometer of the echocardiograph. Arterial and mixed venous blood was obtained for blood-gas analysis. The blood samples for hemodynamic measurement were drawn at the time of the operative incision (event 1), five minutes after implantation of the cup (event 2), after preparation of the femur (event 3), five minutes after insertion of the stem (event 4), five minutes after reduction of the hip joint (event 5), fifteen minutes after reduction of the hip joint (event 6), and two hours after the end of the operation (event 7).

The demographic data as well as the data on the severity and the duration of the transatrial embolic events during total hip arthroplasty in the three groups of patients were analyzed with a two-tailed unpaired t test. A repeated-measures analysis of variance and a Newman-Keuls test for intergroup comparisons were performed for all of the samples used for arterial blood-gas determination, for the measurement of end tidal carbon dioxide levels, and for each set of pulmonary shunt values. Differences were considered significant when the p value was less than 0.05.

Results

Introduction | Materials and Methods | Results | Discussion | References

The thirty-six women and twenty-four men had a mean age of 65.3 years. The mean duration of the operation was markedly shorter in Group 1 (insertion of the femoral component without cement) than in Group 2 (insertion of the component with a conventional cementing technique) or Group 3 (insertion of the component with the bone-vacuum cementing technique) (Table I). There was no significant difference among the three groups of patients with respect to gender, age, body weight, amount of blood loss, or associated systemic disease. A severe systemic disease (class 3 or 4, according to the criteria of the American Society of Anesthesiologists¹) was present in six patients (30 percent) in Group 1 (one had cardiovascular disease, one had hepatic insufficiency, two had chronic obstructive pulmonary disease, and two had hypertension); in six patients (30 percent) in Group 2 (two had hypertension, two had chronic obstructive pulmonary disease, and two had cardiovascular disease); and in seven patients (35 percent) in Group 3 (one had hypertension, one had cerebrovascular disease, two had chronic obstructive pulmonary disease, and three had cardiovascular disease).

No embolic events were observed with use of transesophageal echocardiography during the operative approach to the hip, the dislocation of the joint, the osteotomy of the femoral neck, the reaming of the acetabulum, or the insertion of the cup. Three patients (15 percent) in Group 1 and two patients (10 percent) in Group 2 had a transient grade-2 embolic response (embolic cascades of many fine particles for a duration of no more than six seconds) that was caused by the preparation of the femur with broaches (Table II).

No major transatrial embolisms (grade 2) occurred when a femoral component was implanted without cement (Group 1), and only one (of four seconds' duration) was observed in one patient (5 percent) during fixation of the femoral component with the bone-vacuum cementing technique (Group 3). In contrast, conventional insertion of the stem with cement (Group 2) caused a prolonged grade-2 embolism (a mean duration [and standard deviation] of 11 ± 4 seconds) in seventeen patients (85 percent) (Fig. 4-A). The difference in the intensity and the duration of the echogenic observations among the groups of patients was significant (p < 0.05). No embolic masses with a diameter of more than five millimeters (grade 3) were detected during the operations in Groups 1 and 3. However, such masses were observed after the relocation of the hip joint in ten patients (50 percent) in Group 2 (Fig. 4-B), and the appearance of these masses was directly related to the severity of the echogenic showers of fine particles that had occurred during the insertion of the stem. These macroemboli usually presented as serpentine masses and were probably caused by twisting of a thigh vessel, accumulation of bone marrow, and intravenous clotting during the implantation of the stem.

In five (8 percent) of the sixty patients (three in Group 1, one in Group 2, and one in Group 3), a patent foramen ovale was detected echocardiographically, but a so-called paradoxical embolism was not seen during the operation. Maximum flow of the infusion of the central venous catheter in some patients caused a grade-1 echocardiographic response. The generation of these artifacts can be avoided by retracting the catheter three to four centimeters cephalad and by reducing the amount of fluids to be infused.

The blood pressure in the patients in Groups 1 and 3 did not change markedly during the operation. In Group 2, after the insertion of the femoral component with a conventional cementing technique, fourteen of the seventeen patients who had a cascade of fine emboli (grade 2) reacted with a transient but significant decrease (p < 0.05) of systolic blood pressure of more than twenty millimeters of mercury (2.67 kilopascals) (Table III). The same hypotensive reactions followed the observation of a grade-2 or 3 embolism after the relocation of the hip joint. The heart rhythm and heart rate remained stable in all sixty patients during the operation.

Only slight changes in the intraoperative oxygen saturation values were observed in Groups 1 and 3. The oxygen saturation decreased significantly (p < 0.05) from a mean of 99.5 to 92.9 percent after the insertion of the femoral component with use of a conventional cementing technique (Fig. 5). These changes persisted during and after the relocation of the hip joint. Physiological baseline values were reached only at the end of the operation.

The levels of end tidal carbon dioxide remained stable during the operation in all patients in Groups 1 and 3, but there was a mean decrease of 2.4 millimeters of mercury (0.32 kilopascal), evidence of pulmonary impairment, in Group 2 (Fig. 6). The difference between the mean levels of end tidal carbon dioxide before and after insertion of the femoral component with use of a conventional cementing technique was significant (p < 0.05).

The mean pulmonary shunt values did not change markedly during the operation in the patients who had insertion of the stem without cement (an increase of 2 percent) or insertion with the bone-vacuum cementing technique (an increase of 3.5 percent). In contrast, insertion of the femoral component with a conventional cementing technique was followed by a significant increase of 24 percent (p < 0.05), indicating intraoperative cardiopulmonary impairment (Fig. 7). The baseline pulmonary shunt values calculated at the beginning of the operation were reached again at the end of the operation in most patients who had evidence of an embolism.

The increase in the pulmonary shunt values was markedly greater in the patients who had a poor preoperative physical status (class 3 or 4, according to the system of the American Society of Anesthesiologists¹) than in the healthy patients (class 1 or 2) (Fig. 8). Marked cardiopulmonary dysfunction persisted postoperatively in three of the six patients in Group 2 who had an associated severe systemic disease.

All patients were admitted to the recovery room after the operation. Twenty-two patients (37 percent) needed continuous monitoring of cardiopulmonary function (with electrocardiography, blood-gas analysis, pulsoximetry, measurement of peripheral arterial pressure and central venous pressure, and, if necessary, mechanical ventilation) and were transferred to the intensive-care unit, where they remained for a long duration (mean and standard deviation, 29 ± 9 hours). These circumstances are common in Germany. In the overall series, the mean stay in the recovery room and in the intensive-care unit was 12 ± 7 hours in Group 1, 30 ± 8 hours in Group 2, and 15 ± 5 hours in Group 3. None of the patients had transitory neurological alterations, such as nervousness and restlessness, during the recovery time, and none showed late clinical signs of a respiratory distress syndrome. The mean duration of hospitalization was 10.5 ± 4.5 days in Group 1, 12 ± 3.5 days in Group 2, and 10 ± 5 days in Group 3. Again, it must be pointed out that these long durations of hospitalization are typical for public institutions in Germany.

Discussion

Introduction | Materials and Methods | Results | Discussion | References

The purpose of the present prospective, randomized study was to compare the effect of fixation of the femoral component without cement and that of fixation with use of the bone-vacuum cementing technique on the prevention of fat embolism and cardiopulmonary impairment during total hip arthroplasty. We also evaluated a control group of patients who had insertion of the femoral component with a conventional cementing technique.

Cardiorespiratory effects of fat and bone-marrow embolism (systemic hypotension, hypoxemia, decreased cardiac output and increased pulmonary shunt values, elevated pulmonary-artery pressure, and cardiac arrest) have been examined in laboratory studies and in clinical practice, particularly after insertion of the femoral component with a conventional cementing technique^3,6,21,24,33. Fibrinolytic and lipolytic enzymes within the pulmonary circulation may diminish the effects of the embolic insult and may explain the erratic clinical occurrence of complications^5,6. Nevertheless, the sequelae of severe fat embolism in patients who have preexisting cardiopulmonary damage can be detrimental and can even lead to death^{9,12,22,27,35,39}. A study of data from a total joint registry showed that sudden death occurred during twenty-three (0.16 percent) of 14,469 primary hip arthroplasties in which the femoral component was inserted with cement, but no deaths occurred during 15,411 primary hip arthroplasties performed without cement²². Twenty-one (91 percent) of the twenty-three patients who died during the operation had known preexisting cardiovascular disease.

The decision to insert the femoral component with or without cement is usually based on parameters such as the age, gender, weight, and activity level of the patient as well as the quality of the bone and the anatomy of the proximal part of the femur, which are thought to be associated with the success or failure of the fixation of an implant in bone. The personal experience of the surgeon is also an important factor in the determination of the modality of fixation. Modern techniques of implantation with cement^31,36 provide a maximum bone-acrylic interlock by means of a combination of a lower viscosity of the cement and pressurization. However, these techniques generate extreme intramedullary pressures within the femoral canal, which often exceed the pressures in the general venous circulation and cause a disruption of the thin-walled medullary vessels. The disruption of the vessels allows the intravasation and flow of fat, bone marrow, bone debris, and polymethylmethacrylate through the natural drainage system of the diaphysis, located along the linea aspera, and through the metaphyseal veins^3,7,11,24,37. A number of investigators have stressed the important role of changes in intramedullary pressure in the genesis of intraoperative embolism^3,16,38,39. In an in vitro study of fixation of the femoral component with and without cement, Inadome et al.¹⁵ found that the pressures during the insertion of the femoral component with cement (mean, 3190.6 millimeters of mercury [425.31 kilopascals]) were markedly higher than those during insertion without cement (mean, 125.8 millimeters of mercury [16.8 kilopascals]). Furthermore, the elevation in pressure consistently persisted much longer when polymethylmethacrylate was used.

Some operative measures during the insertion of the stem, particularly in arthroplasties performed with cement, may substantially minimize the amount of widespread systemic delivery of embolic material. Moreover, pulsatile lavage has been shown in experiments to decrease the volume of fat emboli as well as the resultant respiratory changes^4,30. However, it does not eliminate the increase in pulmonary shunt volume associated with fixation of the stem with cement^25,26. In the past, venting of the femoral canal has been recommended to avoid an increase in intramedullary pressure and intravasation of fat and bone marrow^3,8,16,33. However, a simple drill-hole in the cortex was not found to be adequate to relieve intramedullary pressure in clinical practice. Furthermore, obstruction and migration of cement outside the femoral canal were quite frequent, resulting in the abandonment of this technique^16,32. Even the results observed in a study with use of a stem that had a long central cannula for the evacuation of medullary content during insertion¹³ could not be reproduced¹⁴. As a logical advancement of the principle of venting the femur, the bone-vacuum technique was developed, not only to produce an equilibrium in pressure but also to maintain a controlled decreased intramedullary pressure during the insertion of the stem. This is accomplished with use of one drainage cannula placed proximally along the linea aspera and one drainage cannula placed distal to the tip of the stem^7,25.

Transesophageal echocardiography allows fat and bone-marrow elements passing through the heart to be detected during orthopaedic operative procedures and those performed for the treatment of trauma^{6,10,25,38,39}. The nature of the echogenic particles cannot be directly identified, but Christie et al.⁶ found fat and bone marrow in the blood aspirated from the right atrium of patients who had embolization of fine echogenic cascades during hemiarthroplasty, and Woo et al.³⁹ observed a large amount of fat emboli in the pulmonary parenchyma of dogs who had severe echogenic cascades during a revision hip operation. Furthermore, the activation of intravascular coagulation combined with a venous stasis can explain the genesis of the mixed bone-marrow macroemboli observed after reduction of the hip joint^2,20,28,29. Nevertheless, the echocardiographic phenomena cannot be related solely to embolism of medullary content. In our study, maximum flow of the infusion of the central venous catheter caused artifacts similar to a grade-1 microembolism, and the same events could be observed when the tip of the catheter was placed too close to the right atrium.

A potentially important difference among the three study groups was the operative technique used to prepare the femur. In Group 3 (insertion of the femoral component with the bone-vacuum cementing technique), cutting tools coated with a fine, pure diamond surface were used instead of broaches. These special instruments were developed to reduce the production of bone debris as well as to avoid an increase in intramedullary pressure and thus to prevent the risk of embolism of medullary content, which is common when standard broaches are used. In the present study, transesophageal echocardiography showed severe echogenic cascades of fine particles (grade 2) during the preparation of the femur in three patients (15 percent) in Group 1 and in two patients (10 percent) in Group 2, but no embolism was detected in the patients in Group 3. These events, which preceded the actual insertion of the stem, remained subclinical, but they may have had an additive impact on pulmonary function at the end of the operation. Conversely, preparation of the femur with the diamond cutting tools probably contributed to the reduction of cardiorespiratory changes during the later, cementing phase.

Embolization of fat and bone marrow is common when a femoral component is fixed with a conventional cementing technique. Christie et al.⁶ reported echogenic events in nine of ten patients during hemiarthroplasty, and Ulrich et al.³³ found severe transatrial embolism, defined as a cascade of fine echogenic particles, during twelve of thirteen total hip replacements performed with use of polymethylmethacrylate. In the present study, similar phenomena were observed in seventeen patients (85 percent) during conventional cementing of the femoral component and in one patient (5 percent) during fixation of the component with the bone-vacuum cementing technique, but such phenomena did not appear when cement was not used. Even though fixation of the stem without cement appears to be safe, surgeons also should be aware of the risk of embolization during the initial preparation of the femur with broaches or reamers^15,39. The very low rate of embolic events detected during the insertion of the stems without cement may be related to the operative technique used in the present study. When the tapered stem was inserted, there was a tight fit at the edges of the implant, but enough space was left at the site of entrance to ensure decompression of the femoral canal. After stable fixation had been achieved, the gaps between the implant and bone were filled with autologous cancellous bone.

The present study demonstrated that it is not possible to prevent the embolization of fat and marrow completely during total hip arthroplasty with cement. Nevertheless, the application of polymethylmethacrylate with the bone-vacuum cementing technique significantly reduced (p < 0.05) the prevalence of severe and prolonged embolism. This finding does not contrast with the results of a previous study²⁴ in which severe transatrial embolic events (grade 2) were observed with transesophageal echocardiography during thirty-three (94 percent) of thirty-five arthroplasties in which a stem was inserted with a conventional cementing technique but during only five (14 percent) of thirty-five arthroplasties in which a stem was inserted with the bone-vacuum cementing technique.

The timing of echogenic events observed during the insertion of the femoral component and the relocation of the hip joint demonstrated a nearly immediate cause-and-effect relationship between severe embolism (grade 2 or 3) and changes in hemodynamic and cardiorespiratory function. Conversely, anesthesiological monitoring showed no substantial changes in hemodynamic parameters, oxygen saturation, end tidal carbon dioxide levels, and pulmonary shunt values in patients who had no echogenic signs of embolism or those who had a grade-1 embolism. The impairment of hemodynamic and cardiorespiratory function observed after a severe embolic event (grade 2 or 3) in the present study was consistent with the findings in other studies^6,26,31,38.

The blood pressure did not change after the stem was inserted with the bone-vacuum cementing technique or after it was inserted without cement, but hypotension occurred in fourteen patients (70 percent) after insertion of the stem with a conventional cementing technique. Heinrich et al.¹⁰ and Wenda et al.³⁸ also observed severe hypotensive events after major echogenic cascades during total hip arthroplasty performed with cement. We detected significant changes in oxygen saturation (p < 0.05) and end tidal carbon dioxide levels (p < 0.05) only in patients who had severe intraoperative echogenic events after insertion of the stem with a conventional cementing technique. A similar disturbance of the alveolar gas-exchange after echocardiographic diagnosis of embolism was reported by Christie et al.⁶ and Ulrich et al.³³. Of particular interest was the marked increase in the pulmonary shunt values (24 percent) observed in the present study after the femoral component was fixed conventionally with polymethylmethacrylate. Ries et al.²⁶ reported similar changes (28 percent) during total hip arthroplasty with cement, but when fixation was performed without cement the values did not increase markedly, just as they did not increase markedly in the present study (2 percent). In our study, the moderate increase in the mean pulmonary shunt value (3.5 percent) in the patients who had insertion of the component with the bone-vacuum cementing technique (Group 3) confirmed the efficacy of this technique in preventing impairment of cardiopulmonary function.

The method that we used to calculate shunt values from arterial blood-gas measurements might not be sensitive enough to detect subtle alterations, but it is a reliable way to assess changes in the results of comparative investigations²⁶.

Most of the patients in our study were more than sixty years old, and most had limited physical reserve because of severe systemic disease (class 3 or 4, according to the criteria of the American Society of Anesthesiologists¹). The low mechanical resistance of the weak trabeculae in osteoporotic bone may allow a considerable amount of fat and bone-marrow elements to enter the drainage veins of the femur and to reach the systemic circulation. Additional clinical trials are necessary to provide more information to substantiate this hypothesis. Osteoporosis and preexisting diseases, which are common in patients of advanced age, can play an important role in determining the quantity of material reaching the lungs and the ability of the patients to withstand an embolic insult²³. Therefore, the marked cardiorespiratory changes observed in our study after the transatrial embolic events should not necessarily be expected in all patients who have a total hip arthroplasty.

Patients who had a poor physical status (class 3 or 4, according to the criteria of the American Society of Anesthesiologists¹) had a greater risk of cardiopulmonary impairment after intraoperative embolic events. With the numbers available, no specific condition that predisposed the patients to clinically important pulmonary embolization could be identified. Two patients in Group 2 (fixation with a conventional cementing technique) had severe preexisting pulmonary obstructive disease, but only one of them had persistent impairment of respiratory function after the operation.

The duration in the intensive-care unit for protracted continuous monitoring of the cardiopulmonary function of patients who have associated systemic disease and the duration of hospitalization after total hip arthroplasty are typically longer in Europe than in the United States. The mean duration in the intensive-care unit and the mean duration of hospitalization of patients managed in our department were consistent with the experience in public institutions in our country. In the present study, the patients who had the stem inserted without cement and those who had the stem inserted with the bone-vacuum cementing technique were in the intensive-care unit for a shorter mean duration than the patients who had the stem inserted with a conventional cementing technique. However, several medical and logistical factors influenced the time of discharge of patients from the intensive-care unit, and a reliable comparison among groups was not possible.

With regard to the mechanical nature of fat embolism during the operative procedure, the echocardiographic results in the present study confirmed that the maximum amount of embolization of fat and bone-marrow elements occurs during insertion of the femoral component and that embolization is more pronounced after fixation with cement than after fixation without cement. The subsequent cardiorespiratory changes may remain subclinical for patients who have a good preoperative physical status, and they may be clinically important for those who have a poor physical status. Ries et al.²⁶ stated that the ability of a patient to tolerate an increase in intraoperative pulmonary shunt should be considered when the decision is made as to whether or not to fix the femoral component with cement during total hip arthroplasty. Lewallen¹⁸ suggested that the surgeon switch from a femoral stem designed to be inserted with cement to one designed to be inserted without cement if the patient's condition becomes unstable during the operative procedure or if the patient is found to be particularly sensitive to the earlier steps of the procedure that are known to be associated with major amounts of embolic material, such as preparation of the femur with broaches and insertion of the medullary plug²⁴. The present study confirmed that the bone-vacuum cementing technique is an effective alternative to fixation without cement that can be used to reduce the embolization of fat and bone-marrow elements and the risk of cardiopulmonary impairment. Despite the longer operative time and the risk of subsequent fracture of the femur due to the concentration of stress surrounding the venting-hole, which cannot be ignored, the bone-vacuum cementing technique should be seriously considered for patients who have preexisting cardiopulmonary disease. Ulrich³⁴ reported two stress fractures (0.3 percent) beneath the tip of the stem after 600 total hip arthroplasties performed with cement and with use of a distal venting hole. Since 1995, we have performed 130 total hip arthroplasties with use of the bone-vacuum cementing technique, and none of our patients has had a femoral fracture as a result of the procedure.

References

Introduction | Materials and Methods | Results | Discussion | References

American Society of Anesthesiologists: New classification of physical status. Anesthesiology,24: 111-114, 1963.24111 1963

Binns, M., and Pho, R.: Femoral vein occlusion during hip arthroplasty. Clin. Orthop.,255: 168-172, 1990.255168 1990 [PubMed]

Breed, A. L.: Experimental production of vascular hypotension, and bone marrow and fat embolism with methylmethacrylate cement. Clin. Orthop.,102: 227-244, 1974.102227 1974 [PubMed]

Byrick, R. J.; Bell, R. S.; Kay, J. C.; Waddell, J. P.; and Mullen, J. B.: High-volume, high-pressure pulsatile lavage during cemented arthroplasty. J. Bone and Joint Surg.,71-A: 1331-1336, Oct. 1989.71-A1331 1989

Charnley, J.: Risks of total hip replacement [letter]. British Med. J.,4: 101, 1975.4101 1975

Christie, J.; Burnett, R.; Potts, H. R.; and Pell, A. C. H.: Echocardiography of transatrial embolism during cemented and uncemented hemiarthroplasty of the hip. J. Bone and Joint Surg.,76-B(3): 409-412, 1994.76-B(3)409 1994

Draenert, K.: Modern cementing techniques. An experimental study of vacuum insertion of bone cement. Acta Orthop. Belgica,55: 273-293, 1989.55273 1989

Frost, P. M.: Cardiac arrest and bone cement. British Med. J.,3: 524, 1970.3524 1970

Gurd, A. R.: Fat embolism: an aid to diagnosis. J. Bone and Joint Surg.,52-B(4): 732-737, 1970.52-B(4)732 1970

Heinrich, H.; Kremer, P.; Winter, H.; Wörsdörfer O.; Ahnefeld, F. W.; and Wilder-Smith, O.: Embolic events during total hip replacement. An echocardiographic study. Acta Orthop. Belgica,54: 12-17, 1988.5412 1988

Herndon, J. H.; Bechtol, C. O.; and Crickenberger, D. P.: Fat embolism during total hip replacement. A prospective study. J. Bone and Joint Surg.,56-A: 1350-1362, Oct. 1974.56-A1350 1974

Hofmann, S.; Huemer, G.; Kratochwill, C.; Koller-Strametz, J.; Hopf, R.; Schlag, G.; and Salzer, M.: Pathophysiologie der Fettembolie in der Orthopädie und Traumatologie. Orthopäde,24: 84-93, 1995.2484 1995 [PubMed]

Hofmann, S.; Lange, A.; Engel, A.; Salzer, M.; and Eyb, R.: Femoral intramedullary pressure during cemented total hip replacement—comparison of retrograde piston filling versus hyperpressurized transprosthetic drainage system (TDS). Orthop. Trans.,21: 107, 1997.21107 1997

Hofmann, S.: Personal communication.

Inadome, T.; Wall, M. C.; Smith, C. L.; and Whiteside, L. A.: Femoral intramedullary pressure during in vitro cemented and cementless total hip arthroplasty. Orthop. Trans.,22: 154-155, 1998-1999.22154 1998-1999

Kallos, T.; Enis, J. E.; Gollan, F.; and Davis, J. H.: Intramedullary pressure and pulmonary embolism of femoral medullary contents in dogs during insertion of bone cement and a prosthesis. J. Bone and Joint Surg.,56-A: 1363-1367, Oct. 1974.56-A1363 1974

Levy, D.: The fat embolism syndrome. A review. Clin. Orthop.,261: 281-286, 1990.261281 1990 [PubMed]

Lewallen, D. G.: Neurovascular injury associated with hip arthroplasty. J. Bone and Joint Surg.,79-A: 1870-1880, Dec. 1997.79-A1870 1997

Lewallen, D.; Ereth, M.; and Holiday, A.: Fat embolism associated with THA. J. Bone and Joint Surg.,79-B (Supplement II): 172, 1997.79-B (Supplement II)172 1997

Modig, J.; Busch, C.; Olerud, S.; Saldeen, T.; and Waernbaum, G.: Arterial hypotension and hypoxaemia during total hip replacement: the importance of thromboplastic products, fat embolism and acrylic monomers. Acta Anaesth. Scandinavica,19: 28-43, 1975.1928 1975

Orsini, E. C.; Byrick, R. J.; Mullen, B. M.; Kay, J. C.; and Waddell, J. P.: Cardiopulmonary function and pulmonary microemboli during arthroplasty using cemented or non-cemented components. The role of intramedullary pressure. J. Bone and Joint Surg.,69-A: 822-832, July 1987.69-A822 1987

Parvizi, J.; Holiday, A. D.; Ereth, M. H.; and Lewallen, D. G.: Sudden death during primary hip arthroplasty. Read at the Twenty-seventh Open Scientific Meeting and the Fifth Combined Open Meeting of the Hip Society and AAHKS, Anaheim, California, Feb. 7, 1999.

Patterson, B. M.; Healey, J. H.; Cornell, C. N.; and Sharrock, N. E.: Cardiac arrest during hip arthroplasty with a cemented long-stem component. A report of seven cases. J. Bone and Joint Surg.,73-A: 271-277, Feb. 1991.73-A271 1991

Pitto, R. P.; Koessler, M.; and Draenert, K.: Prophylaxis of fat and bone marrow embolism in cemented total hip arthroplasty. Clin. Orthop.,355: 23-34, 1998.35523 1998 [PubMed]

Pitto, R. P.; Schramm, M.; Hohmann, D.; and Koessler, M.: Relevance of the drainage along the linea aspera for the reduction of fat embolism during cemented total hip arthroplasty. A prospective randomized clinical trial. Arch. Orthop. and Trauma Surg.,119: 146-150, 1999.119146 1999

Ries, M. D.; Lynch, F.; Rauscher, L. A.; Richman, J.; Mick, C.; and Gomez, M.: Pulmonary function during and after total hip replacement. Findings in patients who have insertion of a femoral component with and without cement. J. Bone and Joint Surg.,75-A: 581-587, April 1993.75-A581 1993

Rinecker, H.: New clinico-pathophysiological studies on the bone cement implantation syndrome. Arch. Orthop. and Traumatic Surg.,97: 263-274, 1980.97263 1980

Saldeen, T.: Intravascular coagulation in the lungs in experimental fat embolism. Acta Chir. Scandinavica,135: 653-662, 1969.135653 1969

Sharrock, N. E.; Go, G.; Harpel, P. C.; Ranawat, C. S.; Sculco, T. P.; and Salvati, E. A.: Thrombogenesis during total hip arthroplasty. Clin. Orthop.,319: 16-27, 1995.31916 1995 [PubMed]

Sherman, R. M. P.; Byrick, R. J.; Kay, J. C.; Sullivan, T. R.; and Waddell, J. P.: The role of lavage in preventing hemodynamic and blood-gas changes during cemented arthroplasty. J. Bone and Joint Surg.,65-A: 500-506, April 1983.65-A500 1983

Timperley, A. J.; Ling, R. S. M.; and Jones, P. R.: The effect of surgical technique on the quality of hip arthroplasty. J. Bone and Joint Surg.,74-B (Supplement II): 139-140, 1992.74-B (Supplement II)139 1992

Tronzo, R. G.; Kallos, T.; and Wyche, M. Q.: Elevation of intramedullary pressure when methylmethacrylate is inserted in total hip arthroplasty. J. Bone and Joint Surg.,56-A: 714-718, June 1974.56-A714 1974

Ulrich, C.; Burri, C.; Wörsdörfer, O.; and Heinrich, H.: Intraoperative transesophageal two-dimensional echocardiography in total hip replacement. Arch. Orthop. and Traumatic Surg.,105: 274-278, 1986.105274 1986

Ulrich, C.: Stellenwert der Entlastungsbohrung zur Reduzierung der Knochenmarkausschüttung bei zementierten Hüftendoprothesen. Orthopäde,24: 138-143, 1995.24138 1995 [PubMed]

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Figs. 3-A through 3-D: Transesophageal echocardiograms made during total hip arthroplasty, showing the main echogenic patterns. Fig. 3-A: Grade 0. No emboli or small echogenic particles are evident.

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Fig. 3-B Grade 1. A few fine emboli are seen.

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Fig. 3-C Grade 2. A cascade of fine emboli or embolic masses with a diameter as large as five millimeters is evident, and the right atrium is opacified with echogenic material.

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Fig. 3-D Grade 3. Fine emboli are mixed with large embolic masses that have a diameter of more than five millimeters or with serpentine emboli.

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TABLE I DATA ON THE PATIENTS*

Parameter	Group 1 (N = 20)	Group 2 (N = 20)	Group 3 (N = 20)
Gender (M/F)	8/12	7/13	9/11
Age† (yrs.)	65 ± 4.2	63 ± 4.5	67 ± 5.7
Weight† (kg)	72 ± 6	69 ± 5	77 ± 4
Height† (cm)	165 ± 21	171 ± 25	163 ± 22
Duration of op.† (mins.)	58 ± 12	71 ± 22	77 ± 16
Estimated blood loss† (ml)	964 ± 477	1105 ± 456	1012 ± 503
Physical status‡ (no. of patients)
Class 1	8	7	10
Class 2	6	7	3
Class 3	6	5	6
Class 4	0	1	1

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TABLE I DATA ON THE PATIENTS*

Parameter	Group 1 (N = 20)	Group 2 (N = 20)	Group 3 (N = 20)
Gender (M/F)	8/12	7/13	9/11
Age† (yrs.)	65 ± 4.2	63 ± 4.5	67 ± 5.7
Weight† (kg)	72 ± 6	69 ± 5	77 ± 4
Height† (cm)	165 ± 21	171 ± 25	163 ± 22
Duration of op.† (mins.)	58 ± 12	71 ± 22	77 ± 16
Estimated blood loss† (ml)	964 ± 477	1105 ± 456	1012 ± 503
Physical status‡ (no. of patients)
Class 1	8	7	10
Class 2	6	7	3
Class 3	6	5	6
Class 4	0	1	1

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TABLE II TRANSATRIAL EMBOLIC EVENTS DURING THE OPERATION*

Event	Group 1			Group 2			Group 3
Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3
Preparation of femoral canal
No. (percent) of hips	2 (10)	3 (15)		4 (20)	2 (10)
Duration of embolic event† (secs.)	6 ± 2	3 ± 1		5 ± 1.5	4 ± 2
Implantation of stem
No. (percent) of hips	15 (75)			2 (10)	17 (85)		16 (80)	1 (5)
Duration of embolic event† (secs.)	4 ± 3			8 ± 6.5	11 ± 4		7 ± 3	4
Relocation of hip joint
No. (percent) of hips	11 (55)			4 (20)	5 (25)	10 (50)	13 (65)
Duration of embolic event† (secs.)	4 ± 2			5 ± 3.3	4 ± 2.5		4 ± 2

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TABLE II TRANSATRIAL EMBOLIC EVENTS DURING THE OPERATION*

Event	Group 1			Group 2			Group 3
Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3	Grade 1	Grade 2	Grade 3
Preparation of femoral canal
No. (percent) of hips	2 (10)	3 (15)		4 (20)	2 (10)
Duration of embolic event† (secs.)	6 ± 2	3 ± 1		5 ± 1.5	4 ± 2
Implantation of stem
No. (percent) of hips	15 (75)			2 (10)	17 (85)		16 (80)	1 (5)
Duration of embolic event† (secs.)	4 ± 3			8 ± 6.5	11 ± 4		7 ± 3	4
Relocation of hip joint
No. (percent) of hips	11 (55)			4 (20)	5 (25)	10 (50)	13 (65)
Duration of embolic event† (secs.)	4 ± 2			5 ± 3.3	4 ± 2.5		4 ± 2

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TABLE III ARTERIAL BLOOD PRESSURE*

*Group 1 = femoral component inserted without cement, Group 2 = femoral component inserted with a conventional cementing technique, and Group 3 = femoral component inserted with the bone-vacuum cementing technique. The values are given as the mean and the standard deviation in millimeters of mercury, with kilopascals in parentheses. †The difference was significant compared with the other groups (p < 0.05).

	Baseline Value		Value After Insertion of Stem
Diastolic	Systolic	Diastolic	Systolic
Group 1	68 ± 12 (9 ± 1.6)	131 ± 14 (17 ± 1.9)	71 ± 15 (9 ± 2.0)	127 ± 20 (17 ± 2.7)
Group 2	70 ± 16 (9 ± 2.1)	127 ± 9 (17 ± 1.2)	61 ± 13 (8 ± 1.7)	99 ± 18 (13 ± 2.4)†
Group 3	73 ± 13 (10 ± 1.7)	126 ± 12 (17 ± 1.6)	69 ± 9 (9 ± 1.2)	121 ± 16 (16 ± 2.1)

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TABLE III ARTERIAL BLOOD PRESSURE*

*Group 1 = femoral component inserted without cement, Group 2 = femoral component inserted with a conventional cementing technique, and Group 3 = femoral component inserted with the bone-vacuum cementing technique. The values are given as the mean and the standard deviation in millimeters of mercury, with kilopascals in parentheses. †The difference was significant compared with the other groups (p < 0.05).

	Baseline Value		Value After Insertion of Stem
Diastolic	Systolic	Diastolic	Systolic
Group 1	68 ± 12 (9 ± 1.6)	131 ± 14 (17 ± 1.9)	71 ± 15 (9 ± 2.0)	127 ± 20 (17 ± 2.7)
Group 2	70 ± 16 (9 ± 2.1)	127 ± 9 (17 ± 1.2)	61 ± 13 (8 ± 1.7)	99 ± 18 (13 ± 2.4)†
Group 3	73 ± 13 (10 ± 1.7)	126 ± 12 (17 ± 1.6)	69 ± 9 (9 ± 1.2)	121 ± 16 (16 ± 2.1)