- Email: [email protected]
LOWER RISK OF THROMBOEMBOLIC DISEASE AFTER TOTAL HIP REPLACEMENT WITH NON-CEMENTED THAN WITH CEMENTED PROSTHESES
769
Every patient was abnormal in one or more of the tests. Three patients (1,4, and 6) were abnormal in the proctogram only but six (8-13) were abnormal in all three tests. Of the seven patients who could not expel a balloon, five could not expel any barium paste and four expelled 50 ml of fluid. The EMG recordings showed that the puborectalis and external anal sphincter muscles contracted on simulated defaecation in eleven of the thirteen patients. In one of the remaining two, the resting EMG was so active that no change could be detected on voluntary contraction or straining and the pelvic floor was seen to rise when she attempted to expel barium paste. In the final patient the record was technically unsatisfactory because of previous anal surgery.
Preliminary Communication LOWER RISK OF THROMBOEMBOLIC DISEASE AFTER TOTAL HIP REPLACEMENT WITH NON-CEMENTED THAN WITH CEMENTED PROSTHESES
C. W. FRANCIS1
V. J. MARDER1
C. M. EVARTS2
Hematology Unit, Department of Medicine,1 and Department of Orthopaedics,2 University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
Discussion
The experimental models described here show that there is a group of patients with intractable constipation in whom the primary abnormality is an inability to empty the rectum. These patients have difficulty in expelling a semi-solid stool, and most cannot expel a small soft bolus normally. The five patients who were not helped by a high-fibre diet or laxatives were all unable to expel a balloon, barium paste, or more than a small proportion of the fluid from the rectum. Three of these patients also said they were unable to pass flatus. These observations may explain why this severe type of constipation can present such an intractable problem in treatment. Perhaps extra fibre helps patients who can pass soft solid stools, and laxatives may help those who can pass semi-solid material or liquid from the rectum. No dietary or drug therapy is likely to help those who find it almost impossible to expel anything from the rectum. Two patients in this group had had unsuccessful colectomy with ileorectal anastomosis. This operation can help many patients with severe constipation possibly by reducing the consistency of the stool entering the rectum. The failure of this operation to help these two patients can be explained by their difficulty in emptying fluid from the rectum. One had been taught to pass a proctoscope daily to enable her to evacuate anything. When 500 ml saline was introduced she was able to expel only 140 ml with repeated straining over 10 min; when a proctoscope was passed 400 ml fluid drained from the rectum. The other patient said that she was unable to evacuate therapeutic enemas and she expelled only 10 of 500 ml fluid over 4 min. It would be wise to test defaecatory function before this operation is advised. Why do these patients have difficulty in emptying the rectum? All had normal rectoanal inhibitory reflexes, showing that the smooth muscle of the internal anal sphincter relaxed on rectal distension. All except two (patients 11 and 12) felt a normal urge to defaecate as a balloon in the rectum was distended; these two patients did not experience this sensation at any time. Lack of rectal sensation did not, therefore, appear to be a major factor in the failure of defaecation. It appears that these patients tend to contract the striated muscle of the pelvic floor on attempted defaecation, unlike normal subjects in whom relaxation of these muscles occurs. 1,11-13 So far, no medical or surgical treatment has been found that successfully corrects this abnormality.14 G K. T. was McLaughlin fellow, Dalhousie Scotia, Canada.
University, Halifax,
Nova
Summary
antithrombin III plus heparin as prophylaxis against thrombosis after total hip replacement, an unexpectedly low incidence of postoperative thromboembolic disease was found in patients receiving non-cemented (0 of 23) rather than cemented prostheses (4 of 13, 31%). Despite the small number of patients, the difference was significant and necessitated modification of the protocol. These preliminary findings suggest that the type of hip replacement used was more important than the type of antithrombotic medication in preventing venous thrombosis and pulmonary embolism. INTRODUCTION
THROMBOEMBOLIC disease is a common complication after total hip replacement surgery; the incidence of postoperative deep-vein thrombosis is 45-70%,1-4 of pulmonary embolism 10%,5-7 and of fatal pulmonary embolism 1-3%.’’° Although there is controversy about the relative efficacy and risks of anticoagulant prophylaxis, several regimens have been recommended, including aspirin,
dextran, warfarin, and subcutaneous heparin.2,6,8,11-19 During the course of a randomised, prospective trial of two prophylactic anticoagulant regimens in patients having total hip replacement, we found an unexpectedly low incidence of
G. K. TURNBULL AND OTHERS REFERENCES
2.
Lennard-Jones JE. Severe chronic constipation of young women, "Idiopathic Slow Transit Constipation". Gut 1986; 27: 41-48. Binder HJ, Donovitz M A new look at laxative action. Gastroenterology 1975; 69:
3.
Hardcastle JD, Wilkins JL. The action of sennosides and related compounds on human
1. Preston DM,
1001-05. colon and rectum. Gut
1970; 11: 1038-42. DM, Lennard-Jones JE, Thomas BM The balloon proctogram. Br J Surg 1984; 71: 29-32. Preston DM, Lennard-Jones JE Anismus in chronic constipation. Dig Dis Sci 1985;
4. Preston
5.
30: 413-18. 6. Barnes PRH, Lennard-Jones 7. 8.
9. 10.
11. 12. 13.
Correspondence should be addressed to J. E. L.-J., St Mark’s Hospital, City Road, London EC IV 2PS.
the course of a prospective, randomised trial comparing dextran 40 with
During
14.
JE. Balloon expulsion from the rectum in constipation of different types. Gut 1985; 26: 1049-52. Bartram CI, Mahieu PHG. Radiology of the pelvic floor. In: Henry MM, Swash M, ed. Coloproctology and the pelvic floor London Butterworth, 1985: 151-85. Hinton JM, Lennard-Jones JE, Young AC. A new method for studying gut transit time using radio opaque markers. Gut 1969; 10: 842-47. Preston DM, Lennard-Jones JE, Thomas BM. Towards a radiologic definition of idiopathic megacolon Gastrointest Radiol 1985; 10: 167-69. Preston DM, Hawley PR, Lennard-Jones JE, Todd IP. Results of colectomy for severe idiopathic constipation in women (Arbuthnot Lane’s disease). Br J Surg 1984; 71: 547-52. Barnes PRH. Megacolon in adults. Br J Surg 1985; 72 (supply: S10-12. Parks AG, Porter NH, Melzak J. Experimental study of the reflex mechanism controlling the muscles of the pelvic floor. Dis Colon Rect 1962; 5: 407-14. Womack NR, Williams NS, Holmfield JHM, Morrrison JFB, Simpkins KC. New method for the dynamic assessment of anorectal function in constipation. Br J Surg 1985; 72: 994-98 Barnes PRH, Hawley PR, Preston DM, Lennard-Jones JE. Experience of posterior division ofthe puborectalis muscle in the management of chronic constipation. Br J Surg 1985; 72: 475-77.
770 venous thromboembolic disease in who received non-cemented prostheses.
postoperative
patients
PATIENTS AND METHODS
Adult patients scheduled for total hip replacement were eligible for the study if they did not have child-bearing potential, congestive heart failure, allergic sensitivity to iodinated contrast agents, or any disorder thought to present a haemorrhagic risk. All patients gave written, informed consent, according to the Declaration of Helsinki. Younger patients were selected for non-cemented fixation, and patients older than 62 years for cemented hip replacement. The patients were randomly assigned to receive either dextran 40 (loading dose of 10 ml/kg of 6% dextran 40 solutiop begun 2 h before operation and continuously infused over 12 h, followed by a maintenance dose of 7 ml/kg daily as a constant infusion for 5’5 days) or a combination of antithrombin III (’Kybernin’, Hoechst-Roussel, Somerville, New Jersey: intravenously as an initial dose of 1500 U 2 h before operation and 1000 U/day for 5 days) and subcutaneous heparin (5000 U every 12 h beginning 2 h before operation and continuing for 5 days). Cemented total hip replacement used the dual-lock prosthesis, whereas non-cemented porous metal-coated dual-lock prostheses were used. An anterolateral approach was used for both procedures, but there were several differences in technique. Many tiny drill holes were made throughout the subchondral bone with the noncemented porous-coated system, while many seating holes of diameter 5 mm were made for the cemented prosthesis. A metalbacked cup was used after injection of cement under pressure, whereas the porous-coated acetabular cups were driven in with force, depending on a press fit for stability. Introduction of the cemented femoral prostheses also used a plastic plug that blocked distal flow of the cement and allowed pressurisation of cement proximally. The non-cemented system was inserted directly to achieve an external tight press fit. Thigh-length elastic stockings were worn on the non-operated leg after the operation and on the operated leg after removal of the dressing. For the first 2 postoperative days all patients remained in bed with active range of motion exercises; they began ambulation on the 3rd postoperative
day.
venograph
Bilateral ascending was carried out between days 6 and 8 in 33 patients, on day 5 in 1, and on day 9 in 2. Technical problems limited venography to one side only in 2 patients and precluded it in 1 patient. Statistical analysis included Student’s t test, the chi-square test with Yates’ correction,21 and logistic regression analysis, by a Poisson model, of the occurrence of thromboembolic disease onto a function of several clinical variables.
and duration of surgery (B) in cemented or cemented prostheses.
Age (A)
Patients with thrombi
23 patients received a non-cemented total hip replacement and 13 a cemented prosthesis (see table). As would be expected since age was a selection criterion for the type of surgery, the mean age of the cemented group was significantly higher than that of the non-cemented group (72
CHARACTERISTICS OF PATIENTS
indicated
non-
by circled dots.
p<0’ 005) (see figure). The ratio of men to women different in the two groups, but the proportions receiving antithrombin III and heparin or dextran were similar. Duration of surgery was significantly longer (figure) in patients receiving a cemented hip owing to the additional time required for cement preparation and injection. No patient who had a non-cemented hip replacement had venous thrombosis, compared with 31% (4 of 13) of those receiving the cemented prosthesis. A 68-year-old woman who received dextran and an 81-year-old woman who received antithrombin III and heparin had deep-vein thrombosis confined to the calf, venographically detected on days 6 and 7, respectively; a 70-year-old man who received dextran had multiple thrombi on day 6 in small muscular calf veins; and a 75-year-old woman who received antithrombin III and heparin did not have venography, but showed clinical symptoms of pulmonary embolism, confirmed by pulmonary angiography, on the 14th postoperative day. The difference in incidence of thrombotic complications between the two groups was significant by a two-tailed chi-square test (=5-14, p<0’025). When the data were analysed by logistic regression, the type of surgery was significantly v
RESULTS
are
patients receiving
55 years,
was
771
the occurrence of thromboembolic disease while other clinical parameters-age, sex, (p=0-04), duration of surgery, and type of drug prophylaxis-did not contribute.
related
to
DISCUSSION
We thank Beverly Webster, RN, for help in the conduct of this study and Carol Weed for preparing the typescript. This work was supported in part by grant HL-30616 and clinical investigator award (C. W. F.) no HL-00733 from the National Heart, Lung and Blood Institute, Bethesda, Maryland, and by a grant from Hoechst-Roussel Pharmaceuticals. The work was done in part during the tenure of an established investigatorship from the American Heart Association (C. W. F.) and with funds contributed by the New York State
Affiliate,
.
The significant difference in the incidence of postoperative thromboembolic disease in the two groups is due primarily to the remarkable absence of venous thrombosis in patients receiving non-cemented hip replacements. In other studies using venographic diagnosis, the lowest frequencies of6 venous thrombosis include 14% in a dextran-treated group, 11% after prophylaxis with subcutaneous heparin,’8and 13% with adjusted subcutaneous heparin.19 The incidence of thromboembolic disease in our patients receiving cemented ,prostheses (31 %) is similar to that reported in most other studies using anticoagulant prophylaxis and venographic diagnosis, all of which included only patients that received the cemented type of total hip prosthesis. Thus, the range of reported incidence of thromboembolic disease for dextran is 25-57%,’ for warfarin 21-33%,’ for heparin 28-87%,’’’ and for aspirin 25-80%."’’26 Although the significant difference in the age distribution between our two patient groups may account for part of the difference in risk of postoperative thromboembolic disease, the logistic regression analysis indicates that it was not a significant contributor. Sikorski et al4 described an agerelated increased risk of postoperative thromboembolism after hip replacement (35% in patients younger than 61 years compared with 56% in those over 70 years), but most studies have not found a significant relation. 1,8,13,17,23,27,28 Insertion of the cemented prosthesis entails a longer operation because of the need to prepare, pressurise, and inject the cement. While, in general, longer operations predispose to a greater risk of thromboembolism, duration of surgery has not been a significant contributing factor in four studies of total hip replacement.’,’,"," In our study the logistic regression model did not indicate that duration of surgery was an important variable contributing to thromboembolism; there was considerable overlap in duration in the two groups, and the patients with thrombi were represented throughout the distribution (figure). The surgical technique, type of prosthesis, and absence of cement could also contribute to the lower incidence of thrombi in the non-cemented group. The monomer of the methylmethacrylate cement circulates after injection29 and could help cause a hypercoagulable state. The high-pressure injection of cement into the medullary cavity releases fat, bone-marrow cells, and platelets into the circulation, and these materials have been found in association with fibrin in the lungs.3o,3i Also, the heat released during polymerisation of the cement could cause endothelial damage in contiguous veins, which may predispose to thrombosis. The use of non-cemented prostheses is increasing because of evidence that there is less loosening of the prosthesis with time, making fewer revisions necessary, and making the operation applicable to younger patients. Our finding that patients receiving a non-cemented prosthesis may also have a lower incidence of postoperative thromboembolic complications is preliminary and must be interpreted cautiously, since small numbers were involved and the study was not designed to investigate this relation. However, the lower risk of postoperative thromboembolism may justify clinical trials to establish whether less intensive anticoagulant prophylaxis will be effective in such patients.
Inc.
Correspondence should be addressed to C. W. F., PO Box 610, Hematology Unit, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, USA.
REFERENCES 1
Hampson WGJ, Lucas HK, Harris FC, Roberts PH. Failure of low-dose heparin to prevent deep-vein thrombosis after hip-replacement arthroplasty. Lancet 1974; ii.
2.
Sagar S, Stamatakts JD, Higgins AF, et al. Efficacy of low-dose heparin in prevention of extensive deep-vein thrombosis in patients undergoing total-hip replacement.
795-97.
Lancet 1976; i: 1151-54. EW, Harris WH. Prevention of venous thromboembolism in orthopaedic patients. J Bone Joint Surg 1976, 58-A: 903-12. Sikorski JM, Hampson WG, Staddon GE The natural history and aetiology of deep vein thrombosis after total hip replacement. J Bone Joint Surg 1981, 63-B: 171-77. Harris WH, Salzman EW, DeSanctis RW. The prevention of thromboembolic disease by prophylactic anticoagulation J Bone Joint Surg 1967; 49-A: 81-89 Evarts CM, Fell EJ. Prevention ofthromboembolic disease after elective surgery ofthe hip. J Bone Joint Surg 1971; 53-A: 1271-80. Johnson R, Green JR, Charnley J. Pulmonary embolism and its prophylaxis following the Charnley total hip replacement. Clin Orthop Rel Res 1977; 127: 123-32. Tubiana R, Duparc J. Prevention of thrombo-embolic complications in orthopaedic and accident surgery. J Bone Joint Surg 1961; 43-B: 7-15. Coventry MB, Nolan DR, Beckenbaugh RD. "Delayed" prophylactic anticoagulation: a study of results and complications in 2,012 total hip arthroplasties J Bone Joint Surg 1973; 55-A: 1487-92. Lowe LW. Venous thrombosis and embolism. J Bone Joint Surg 1981; 63-B: 155-67. Harris WH, Salyman EW, Athanasoulis CA, Waltman AC, DeSanctis RW. Aspirin prophylaxis of venous thromboembolism after total hip replacement. N Engl J Med
3. Salzman 4. 5.
6. 7.
8 9.
10. 11.
1977; 297: 1246-49. WH, Athanasoulis CA, Waltman AC, Salzman EW. High and low-dose aspirin prophylaxis against venous thromboembolic disease in total hip replacement. J Bone Joint Surg 1982; 64-A: 63-66 13. Harris WH, Salzman EW, DeSanctis RW, Coutts RD. Prevention of venous thromboembolism following total hip replacement. JAMA 1972; 220: 1319-22. 14. Rothermel JE, Weissinger JB, Stinchfield FE. Dextran 40 and thromboembolism in total hip replacement surgery. Arch Surg 1973; 106: 135-37. 15. Bergqvist D, Efsing HO, Hallbook T, Hedlund T. Thromboembolism after elective 12. Harris
and post-traumatic hip surgery-a controlled prophylactic trial with dextran 70 and low-dose heparin. Acta Chir Scand 1979; 145: 213-18. 16. Salzman DW, Harris WH, DeSanctis RW Anticoagulation for prevention of
thromboembolism following fractures ofthe hip. N Engl J Med 1966; 275: 122-30 CW, Marder VJ, Evarts CM, Yaukoolbodi S. Two-step warfarin therapy. Prevention of postoperative venous thrombosis without excessive bleeding. JAMA 1983; 249: 374-78. Morris GK, Henry APJ, Preston BJ. Prevention of deep-vein thrombosis by low-dose heparin in patients undergoing total hip replacement. Lancet 1974; ii: 797-800. Leyvraz PF, Richard J, Bachmann F, et al. Adjusted versus fixed-dose subcutaneous heparin in the prevention of deep-vein thrombosis after total hip replacement. N Engl J Med 1983; 309: 954-58. DeWeese JA, Rogoff SM. Phlebographic patterns of acute deep venous thrombosis of the leg. Surgery 1963; 53: 99-108. Snedcor GW, Cochran WG. Statistical methods, 7th ed. Ames, Iowa: Iowa State
17. Francis
18. 19.
20 21.
University Press, 1980 WH, Salzman EW, Athanasoulis C, Waltman AC, Baum S, DeSanctis RW. Comparison of warfarin, low-molecular-weight dextran, aspirin, and subcutaneous heparin in prevention of venous thromboembolism following total hip replacement. J Bone Joint Surg 1974; 56-A: 1552-62. Johnson R, Charmichael JHE, Almond HGA, Loynes RP. Deep venous thrombosis following Charnley arthroplasty. Clin Orthop Rel Res 1978; 132: 24-30. Pinto DJ. Controlled trial of an anticoagulant (warfarin sodium) in the prevention of venous thrombosis following hip surgery Br J Surg 1970; 57: 349-52. Evarts CM, Alfidi RJ Thromboembolism after total hip reconstruction JAMA 1973;
22. Harris
23.
24. 25.
225: 515-16 JD, Kakkar VV, Lawrence D, Bentley PG, Nairn D, Ward V. Failure of aspirin to prevent postoperative deep vein thrombosis in patients undergoing total hip replacement. Br Med J 1978, i: 1031 Salvati EA, Lachiewicz P. Thromboembolism following total hip-replacement arthroplasty. The efficacy of dextran-aspirin and dextran-warfarin in prophylaxis J Bone Joint Surg 1976; 58-A: 921-25 Hume M, Turner RH, Kuriakose TX, Surprenant J. Venous thrombosis after total hip replacement. Combined monitoring as a guide for prophylaxis and treatment. J Bone Joint Surg 1976; 58-A: 933-38. Ling RSM, James ML. Blood pressure and bone cement Br Med J1971, ii 404 Modig J, Busch C, Olerad S, Saldeen T, Waernbaum G, Arterial hypotension and hypoxaemia during total hip replacement: the importance of thromboplastic products, fat embolism and acrylic monomers. Arch Anaesthesiol Scand 1975; 19: 28-43 Alexander JP, Barron DW. Biochemical disturbances associated with total hip replacement J Bone Joint Surg 1979; 61-B: 101-06
26. Stamatakis
27.
28.
29. 30.
31.
Every patient was abnormal in one or more of the tests. Three patients (1,4, and 6) were abnormal in the proctogram only but six (8-13) were abnormal in all three tests. Of the seven patients who could not expel a balloon, five could not expel any barium paste and four expelled 50 ml of fluid. The EMG recordings showed that the puborectalis and external anal sphincter muscles contracted on simulated defaecation in eleven of the thirteen patients. In one of the remaining two, the resting EMG was so active that no change could be detected on voluntary contraction or straining and the pelvic floor was seen to rise when she attempted to expel barium paste. In the final patient the record was technically unsatisfactory because of previous anal surgery.
Preliminary Communication LOWER RISK OF THROMBOEMBOLIC DISEASE AFTER TOTAL HIP REPLACEMENT WITH NON-CEMENTED THAN WITH CEMENTED PROSTHESES
C. W. FRANCIS1
V. J. MARDER1
C. M. EVARTS2
Hematology Unit, Department of Medicine,1 and Department of Orthopaedics,2 University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
Discussion
The experimental models described here show that there is a group of patients with intractable constipation in whom the primary abnormality is an inability to empty the rectum. These patients have difficulty in expelling a semi-solid stool, and most cannot expel a small soft bolus normally. The five patients who were not helped by a high-fibre diet or laxatives were all unable to expel a balloon, barium paste, or more than a small proportion of the fluid from the rectum. Three of these patients also said they were unable to pass flatus. These observations may explain why this severe type of constipation can present such an intractable problem in treatment. Perhaps extra fibre helps patients who can pass soft solid stools, and laxatives may help those who can pass semi-solid material or liquid from the rectum. No dietary or drug therapy is likely to help those who find it almost impossible to expel anything from the rectum. Two patients in this group had had unsuccessful colectomy with ileorectal anastomosis. This operation can help many patients with severe constipation possibly by reducing the consistency of the stool entering the rectum. The failure of this operation to help these two patients can be explained by their difficulty in emptying fluid from the rectum. One had been taught to pass a proctoscope daily to enable her to evacuate anything. When 500 ml saline was introduced she was able to expel only 140 ml with repeated straining over 10 min; when a proctoscope was passed 400 ml fluid drained from the rectum. The other patient said that she was unable to evacuate therapeutic enemas and she expelled only 10 of 500 ml fluid over 4 min. It would be wise to test defaecatory function before this operation is advised. Why do these patients have difficulty in emptying the rectum? All had normal rectoanal inhibitory reflexes, showing that the smooth muscle of the internal anal sphincter relaxed on rectal distension. All except two (patients 11 and 12) felt a normal urge to defaecate as a balloon in the rectum was distended; these two patients did not experience this sensation at any time. Lack of rectal sensation did not, therefore, appear to be a major factor in the failure of defaecation. It appears that these patients tend to contract the striated muscle of the pelvic floor on attempted defaecation, unlike normal subjects in whom relaxation of these muscles occurs. 1,11-13 So far, no medical or surgical treatment has been found that successfully corrects this abnormality.14 G K. T. was McLaughlin fellow, Dalhousie Scotia, Canada.
University, Halifax,
Nova
Summary
antithrombin III plus heparin as prophylaxis against thrombosis after total hip replacement, an unexpectedly low incidence of postoperative thromboembolic disease was found in patients receiving non-cemented (0 of 23) rather than cemented prostheses (4 of 13, 31%). Despite the small number of patients, the difference was significant and necessitated modification of the protocol. These preliminary findings suggest that the type of hip replacement used was more important than the type of antithrombotic medication in preventing venous thrombosis and pulmonary embolism. INTRODUCTION
THROMBOEMBOLIC disease is a common complication after total hip replacement surgery; the incidence of postoperative deep-vein thrombosis is 45-70%,1-4 of pulmonary embolism 10%,5-7 and of fatal pulmonary embolism 1-3%.’’° Although there is controversy about the relative efficacy and risks of anticoagulant prophylaxis, several regimens have been recommended, including aspirin,
dextran, warfarin, and subcutaneous heparin.2,6,8,11-19 During the course of a randomised, prospective trial of two prophylactic anticoagulant regimens in patients having total hip replacement, we found an unexpectedly low incidence of
G. K. TURNBULL AND OTHERS REFERENCES
2.
Lennard-Jones JE. Severe chronic constipation of young women, "Idiopathic Slow Transit Constipation". Gut 1986; 27: 41-48. Binder HJ, Donovitz M A new look at laxative action. Gastroenterology 1975; 69:
3.
Hardcastle JD, Wilkins JL. The action of sennosides and related compounds on human
1. Preston DM,
1001-05. colon and rectum. Gut
1970; 11: 1038-42. DM, Lennard-Jones JE, Thomas BM The balloon proctogram. Br J Surg 1984; 71: 29-32. Preston DM, Lennard-Jones JE Anismus in chronic constipation. Dig Dis Sci 1985;
4. Preston
5.
30: 413-18. 6. Barnes PRH, Lennard-Jones 7. 8.
9. 10.
11. 12. 13.
Correspondence should be addressed to J. E. L.-J., St Mark’s Hospital, City Road, London EC IV 2PS.
the course of a prospective, randomised trial comparing dextran 40 with
During
14.
JE. Balloon expulsion from the rectum in constipation of different types. Gut 1985; 26: 1049-52. Bartram CI, Mahieu PHG. Radiology of the pelvic floor. In: Henry MM, Swash M, ed. Coloproctology and the pelvic floor London Butterworth, 1985: 151-85. Hinton JM, Lennard-Jones JE, Young AC. A new method for studying gut transit time using radio opaque markers. Gut 1969; 10: 842-47. Preston DM, Lennard-Jones JE, Thomas BM. Towards a radiologic definition of idiopathic megacolon Gastrointest Radiol 1985; 10: 167-69. Preston DM, Hawley PR, Lennard-Jones JE, Todd IP. Results of colectomy for severe idiopathic constipation in women (Arbuthnot Lane’s disease). Br J Surg 1984; 71: 547-52. Barnes PRH. Megacolon in adults. Br J Surg 1985; 72 (supply: S10-12. Parks AG, Porter NH, Melzak J. Experimental study of the reflex mechanism controlling the muscles of the pelvic floor. Dis Colon Rect 1962; 5: 407-14. Womack NR, Williams NS, Holmfield JHM, Morrrison JFB, Simpkins KC. New method for the dynamic assessment of anorectal function in constipation. Br J Surg 1985; 72: 994-98 Barnes PRH, Hawley PR, Preston DM, Lennard-Jones JE. Experience of posterior division ofthe puborectalis muscle in the management of chronic constipation. Br J Surg 1985; 72: 475-77.
770 venous thromboembolic disease in who received non-cemented prostheses.
postoperative
patients
PATIENTS AND METHODS
Adult patients scheduled for total hip replacement were eligible for the study if they did not have child-bearing potential, congestive heart failure, allergic sensitivity to iodinated contrast agents, or any disorder thought to present a haemorrhagic risk. All patients gave written, informed consent, according to the Declaration of Helsinki. Younger patients were selected for non-cemented fixation, and patients older than 62 years for cemented hip replacement. The patients were randomly assigned to receive either dextran 40 (loading dose of 10 ml/kg of 6% dextran 40 solutiop begun 2 h before operation and continuously infused over 12 h, followed by a maintenance dose of 7 ml/kg daily as a constant infusion for 5’5 days) or a combination of antithrombin III (’Kybernin’, Hoechst-Roussel, Somerville, New Jersey: intravenously as an initial dose of 1500 U 2 h before operation and 1000 U/day for 5 days) and subcutaneous heparin (5000 U every 12 h beginning 2 h before operation and continuing for 5 days). Cemented total hip replacement used the dual-lock prosthesis, whereas non-cemented porous metal-coated dual-lock prostheses were used. An anterolateral approach was used for both procedures, but there were several differences in technique. Many tiny drill holes were made throughout the subchondral bone with the noncemented porous-coated system, while many seating holes of diameter 5 mm were made for the cemented prosthesis. A metalbacked cup was used after injection of cement under pressure, whereas the porous-coated acetabular cups were driven in with force, depending on a press fit for stability. Introduction of the cemented femoral prostheses also used a plastic plug that blocked distal flow of the cement and allowed pressurisation of cement proximally. The non-cemented system was inserted directly to achieve an external tight press fit. Thigh-length elastic stockings were worn on the non-operated leg after the operation and on the operated leg after removal of the dressing. For the first 2 postoperative days all patients remained in bed with active range of motion exercises; they began ambulation on the 3rd postoperative
day.
venograph
Bilateral ascending was carried out between days 6 and 8 in 33 patients, on day 5 in 1, and on day 9 in 2. Technical problems limited venography to one side only in 2 patients and precluded it in 1 patient. Statistical analysis included Student’s t test, the chi-square test with Yates’ correction,21 and logistic regression analysis, by a Poisson model, of the occurrence of thromboembolic disease onto a function of several clinical variables.
and duration of surgery (B) in cemented or cemented prostheses.
Age (A)
Patients with thrombi
23 patients received a non-cemented total hip replacement and 13 a cemented prosthesis (see table). As would be expected since age was a selection criterion for the type of surgery, the mean age of the cemented group was significantly higher than that of the non-cemented group (72
CHARACTERISTICS OF PATIENTS
indicated
non-
by circled dots.
p<0’ 005) (see figure). The ratio of men to women different in the two groups, but the proportions receiving antithrombin III and heparin or dextran were similar. Duration of surgery was significantly longer (figure) in patients receiving a cemented hip owing to the additional time required for cement preparation and injection. No patient who had a non-cemented hip replacement had venous thrombosis, compared with 31% (4 of 13) of those receiving the cemented prosthesis. A 68-year-old woman who received dextran and an 81-year-old woman who received antithrombin III and heparin had deep-vein thrombosis confined to the calf, venographically detected on days 6 and 7, respectively; a 70-year-old man who received dextran had multiple thrombi on day 6 in small muscular calf veins; and a 75-year-old woman who received antithrombin III and heparin did not have venography, but showed clinical symptoms of pulmonary embolism, confirmed by pulmonary angiography, on the 14th postoperative day. The difference in incidence of thrombotic complications between the two groups was significant by a two-tailed chi-square test (=5-14, p<0’025). When the data were analysed by logistic regression, the type of surgery was significantly v
RESULTS
are
patients receiving
55 years,
was
771
the occurrence of thromboembolic disease while other clinical parameters-age, sex, (p=0-04), duration of surgery, and type of drug prophylaxis-did not contribute.
related
to
DISCUSSION
We thank Beverly Webster, RN, for help in the conduct of this study and Carol Weed for preparing the typescript. This work was supported in part by grant HL-30616 and clinical investigator award (C. W. F.) no HL-00733 from the National Heart, Lung and Blood Institute, Bethesda, Maryland, and by a grant from Hoechst-Roussel Pharmaceuticals. The work was done in part during the tenure of an established investigatorship from the American Heart Association (C. W. F.) and with funds contributed by the New York State
Affiliate,
.
The significant difference in the incidence of postoperative thromboembolic disease in the two groups is due primarily to the remarkable absence of venous thrombosis in patients receiving non-cemented hip replacements. In other studies using venographic diagnosis, the lowest frequencies of6 venous thrombosis include 14% in a dextran-treated group, 11% after prophylaxis with subcutaneous heparin,’8and 13% with adjusted subcutaneous heparin.19 The incidence of thromboembolic disease in our patients receiving cemented ,prostheses (31 %) is similar to that reported in most other studies using anticoagulant prophylaxis and venographic diagnosis, all of which included only patients that received the cemented type of total hip prosthesis. Thus, the range of reported incidence of thromboembolic disease for dextran is 25-57%,’ for warfarin 21-33%,’ for heparin 28-87%,’’’ and for aspirin 25-80%."’’26 Although the significant difference in the age distribution between our two patient groups may account for part of the difference in risk of postoperative thromboembolic disease, the logistic regression analysis indicates that it was not a significant contributor. Sikorski et al4 described an agerelated increased risk of postoperative thromboembolism after hip replacement (35% in patients younger than 61 years compared with 56% in those over 70 years), but most studies have not found a significant relation. 1,8,13,17,23,27,28 Insertion of the cemented prosthesis entails a longer operation because of the need to prepare, pressurise, and inject the cement. While, in general, longer operations predispose to a greater risk of thromboembolism, duration of surgery has not been a significant contributing factor in four studies of total hip replacement.’,’,"," In our study the logistic regression model did not indicate that duration of surgery was an important variable contributing to thromboembolism; there was considerable overlap in duration in the two groups, and the patients with thrombi were represented throughout the distribution (figure). The surgical technique, type of prosthesis, and absence of cement could also contribute to the lower incidence of thrombi in the non-cemented group. The monomer of the methylmethacrylate cement circulates after injection29 and could help cause a hypercoagulable state. The high-pressure injection of cement into the medullary cavity releases fat, bone-marrow cells, and platelets into the circulation, and these materials have been found in association with fibrin in the lungs.3o,3i Also, the heat released during polymerisation of the cement could cause endothelial damage in contiguous veins, which may predispose to thrombosis. The use of non-cemented prostheses is increasing because of evidence that there is less loosening of the prosthesis with time, making fewer revisions necessary, and making the operation applicable to younger patients. Our finding that patients receiving a non-cemented prosthesis may also have a lower incidence of postoperative thromboembolic complications is preliminary and must be interpreted cautiously, since small numbers were involved and the study was not designed to investigate this relation. However, the lower risk of postoperative thromboembolism may justify clinical trials to establish whether less intensive anticoagulant prophylaxis will be effective in such patients.
Inc.
Correspondence should be addressed to C. W. F., PO Box 610, Hematology Unit, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, USA.
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