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Effect of calf-thigh intermittent pneumatic compression device after total hip arthroplasty: comparative analysis with plantar compression on the effectiveness of reducing thrombogenesis and leg swelling
J Orthop Sci (2003) 8:807–811 DOI 10.1007/s00776-003-0706-y
Effect of calf-thigh intermittent pneumatic compression device after total hip arthroplasty: comparative analysis with plantar compression on the effectiveness of reducing thrombogenesis and leg swelling Motoyuki Fujisawa, Masatoshi Naito, Isao Asayama, Taichi Kambe, and Kei Koga Department of Orthopaedic Surgery, Fukuoka University School of Medicine, 45-1 Nanakuma, Johnan-ku, Fukuoka 814-0180, Japan
Abstract The purpose of this study was to evaluate the efficacy of two intermittent pneumatic compression devices as prophylaxis against intravascular coagulation and leg swelling following total hip arthroplasty. We studied 121 patients by assessing thrombogenesis using the D-dimer level before and after total hip arthroplasty. In addition, the patients’ postoperative swelling was evaluated by measuring the thigh and lower leg circumference. Altogether, 58 patients were assigned to the calf-thigh pneumatic compression group, and the other 63 were assigned to the plantar compression group; the two pneumatic compression devices were compared to evaluate which was more effective for reducing thrombogenesis. At 7 days postoperatively, the mean D-dimer levels of the calfthigh compression group and the plantar compression group were 8.86 and 9.26 µg/ml, respectively. There was no significant difference (P ⫽ 0.697) between the two groups. However, the increased ratio of the circumference of the thigh, which was compared after arthroplasty, averaged 1.22% in the calfthigh compression group and 3.19% in the plantar compression group, which was significantly different (P ⬍ 0.01). Calf-thigh pneumatic compression was found to be more effective than plantar compression for reducing thigh swelling during the early postoperative stage. Key words Deep vein thrombosis · Intermittent pneumatic compression · Calf-thigh pneumatic compression
Introduction Ever since Gardner and Fox8 described a physiological pumping mechanism in the foot and the venous foot pump for preventing deep vein thrombosis (DVT) there have been numerous studies documenting the safety, inexpensiveness, and effectiveness of intermittent pneumatic compression (IPC) for preventing DVT after
Offprint requests to: M. Fujisawa Received: April 9, 2003 / Accepted: July 11, 2003
hip2,6,12,13 and knee7,14,16 arthroplasties. Most of these authors described the results obtained when the foot pump was used. In the meantime, Elliott et al.5 carried out a comparison of the calf-thigh pump with the plantar pump, exploring the possibility of preventing DVT after trauma. They conducted their study using ultrasonography and reported a lower incidence of DVT in the calf-thigh pump group. In reports on the use of the calf-thigh pump after total hip arthroplasty (THA), the prevalence of proximal DVT was reported to be 6% by Woolson17 and 3.8% by Hooker et al.9 The effect of the calf-thigh pump seemed similar to that of the plantar pump, with the incidence of DVT after plantar pump use reported as 3.3% by Bradley et al.2 Few reports, however, have precisely compared the effect of the calf-thigh pump and the plantar pump after THA. The optimal characteristics of these pumps for reducing DVT after THA have not been established. Westrich et al.15 evaluated seven pneumatic compression devices, including the plantar and calf-thigh pumps. They reported that calf and foot and calf pneumatic compression produced the greatest increase in peak venous velocity, whereas the calf-thigh pump produced the greatest increase in venous volume. However, their examination was performed on only 10 patients, and the results of their venous velocity and volume measurements varied widely, which weakens the validity of their results. Therefore, we compared the calf-thigh pump with the plantar pump to evaluate the effectiveness of reducing thrombogenesis and leg swelling after 121 THAs.
Materials and methods A series of 121 patients who had undergone THA were randomly allocated in the order in which they had been hospitalized: 58 patients in the calf-thigh pump group
808
M. Fujisawa et al.: Calf-thigh pumping after THA
Table 1. Specifications of two intermittent pneumatic compression devices Device Calf-thigh pump (Medomer) Foot pump (A-V impulse system)
Chamber
Pressure (mmHg)
Cycle time (s)
Inflation time (s)
2
20–80
14
3.1
1
120–160
20
0.4
who were fitted with the Medomer Automatic Air Massager (Nitto Kohki, Tokyo, Japan) and 63 patients in the plantar pump group who were fitted with the A-V impulse system (Orthofix Vascular Novamedix, Andover, UK). These two IPC devices are different with respect to the number of chambers, air pressure, cycles of inflation, and inflation times (Table 1). The exclusion criteria caused any patients with a history of DVT, pulmonary embolism, congestive heart failure, venous insufficiency, or the presence of a malignant tumor to be excluded from the study. Informed consent was obtained from all patients. All 121 arthroplasties were performed by the same surgeon. The procedures were done with the patient in the lateral decubitus position under epidural anesthesia, with implantation of the uncemented acetabular shell and femoral stem (VerSys Prosthesis, Zimmer). We assayed the D-dimer to evaluate intravascular coagulation preoperatively and again on days 7, 14, and 21 postoperatively. The D-dimer testing was performed by latex immunoassay. We also measured the circumferences of the thigh and lower leg to evaluate postoperative swelling of the legs. The circumference of the thigh (COT) was measured at a point 10 cm above the upper pole of the patella, and the circumference of the lower leg (COL) was measured at the widest point of the lower leg. The COT and COL of the bilateral legs were marked on the skin with an indelible marker preoperatively. We took the measurements at 6 a.m. on the day of the operation and again at the same time on days 3, 7, 14, and 21 postoperatively. Each of the measurement values was the median of three measurements; they were compared to the preoperative measurements (taken as 100%). All patients in both groups underwent the same postoperative management. Immediately after the operation, all patients were fitted with either a plantar pump or a calf-thigh pump. The fitting time for both groups was 4 h per day over a period of 21 days in all patients based on the report7 from our department indicating that there was no significant difference in the D-dimer level after arthroplasty for patients who were fitted with an IPC 4 h per day and those who were fitted 18 h per day. All patients began to walk on the third day after
Table 2. Demographic data for patients in the two groups Parameter
Calf-thigh pump
Plantar pump
No. Male : female Age (years), mean and range Duration of operation (min), mean and range Body mass index, mean and range
58 8 : 50 61.36 (20–84) 94.7 (55–180) 23.6 (16.1–39.4)
63 10 : 53 62.21 (41–86) 95.5 (55–225) 24.1 (18.1–37.0)
surgery and were able to bear nearly their full weight on the operated leg. They were discharged 3 weeks after the operation. No anticoagulant drugs or antiembolism stockings were used. Statistical analyses of the patient data were performed using the chi-square test for gender and Student’s t-test for age, duration of the operation, and body mass index. The D-dimer values and the circumference measurements were analyzed using Student’s t-test for a comparison of the two groups. The paired t-test was used to compare the differences between weeks.
Results All 121 patients completed the trial. The two groups were well matched with regard to gender, age, leg operated on, duration of the operation, and body mass index (Table 2). There were no significant differences in baseline characteristics between the two groups. None of the 121 patients developed the typical symptoms of DVT or pulmonary embolism. D-dimer Preoperatively, the D-dimer levels averaged 0.94 µg/ml in the calf-thigh pump group and 0.88 µg/ml in the plantar pump group (Table 3). On postoperative day (POD) 7, the mean D-dimer levels were 8.86 µg/ml in the calf-thigh pump group and 9.26 µg/ml in the plantar pump group. The D-dimer levels of both groups showed significant increases over their preoperative values (P ⬍
M. Fujisawa et al.: Calf-thigh pumping after THA
809
Table 3. Postoperative changes in D-dimer levels: calf-thigh pump versus plantar pump groups Change in D-dimer levels (µg/ml) Days after operation
Calf-thigh pump
Before operation 7 14 21
0.94 8.86 8.99 5.81
⫾ 1.38 ⫾ 6.09 ⫾ 6.67 ⫾ 4.75
* NS *
Plantar pump
P
⫾ 0.71 ⫾ 4.87 ⫾ 4.65 ⫾ 3.09
NS NS NS NS
0.88 9.26 8.92 5.33
* NS *
* ⬍ 0.01
Fig. 1. Curves (circles, calf-thigh pump; diamonds, plantar pump group) show changes in the circumference of the thigh (COT). Reduction of Postoperative swelling was reduced earlier in the calf-thigh pump group than in the plantar pump group. The average COT of the calf-thigh pump group was significantly smaller (by 1.98%) than that of the plantar pump group at postoperatively day 7 (P ⬍ 0.01)
Fig. 2. Curves (circles, calf-thigh pump; diamonds, plantar pump group) show changes in the circumference of the lower leg (COL). The COL of the calf-thigh pump group was smaller than that of the plantar pump group. The reduction in the plantar pump group from days 14 to 21 was significant (P ⬍ 0.01)
0.0001). However, there were no significant differences from POD 7 to POD 14 in either group. The mean Ddimer level was significantly decreased from POD 14 to POD 21 in both groups (P ⬍ 0.0001). No statistically significant differences were observed between the two groups in regard to mean D-dimer levels for any assay date.
and from POD 7 to POD 14 (2.11%) (P ⬍ 0.001). The plantar pump group showed deterioration on POD 7 compared to that on POD 3. This was followed by a significant reduction (3.68%) (P ⬍ 0.001) from POD 7 to POD 14. Thus, the postoperative swelling in the calf-thigh pump group was reduced earlier than in the plantar pump group. The COL of the operated legs (Fig. 2) was smaller in the calf-thigh pump group than in the plantar pump group on each day measurements were taken, but the difference between the two groups was not significant. The COL of the operated legs from POD 14 to POD 21 after the operation in the plantar pump group was significantly reduced (P ⬍ 0.01).
Postoperative swelling of lower extremity The results of the circumference measurements of the thighs of the operated legs showed no significant differences at POD 3 (Fig. 1). However, by POD 7, the COT in the calf-thigh pump group was significantly smaller (by 1.98%) than that of the plantar pump group (P ⬍ 0.01). On PODs 14 and 21, no significant differences were seen between the two groups. In terms of the timedependent changes of the postoperative swelling reduction, the calf-thigh pump group showed a significant reduction from POD 3 to POD 7 (1.76%) (P ⬍ 0.01)
Discussion Studies evaluating DVT once depended on venography2,6,13,16 but have recently employed ultrasonogra-
810
phy.5,9,12,14,17 We assayed the D-dimer level to evaluate intravascular coagulation preoperatively and postoperatively because the procedure is objective, has greater reliability, and is less invasive and laborintensive than venography or venous ultrasonography. The assay can be done by the usual blood collection method. D-dimer is a degradation product that occurs when a thrombus is dissolved by the fibrinolytic system. This activation occurs after the solidification stage. Thus, an elevated D-dimer level in the blood indicates the existence of venous thrombosis. A high value for the D-dimer concentration has been reported to show a strong correlation with DVT results obtained by venography3 or venous ultrasonography.1 On day 7 after arthroplasty in a previous study conducted by our institute,7 the D-dimer level in patients using the foot pump was 10.5 µg/ml, whereas in patients using no pump it was significantly elevated (to 16.5 µg/ ml). In the present study, we found that the D-dimer levels were less than 10 µg/ml in both the plantar and calf-thigh pump groups, and there were no significant differences between the two groups in regard to sequential D-dimer values. These results suggest that the calfthigh pump is similar to the plantar pump in terms of its effectiveness in reducing thrombogenesis after THA. In addition, the D-dimer remained higher for 2 weeks after THA but decreased significantly thereafter. These results suggest that thrombus existed to a certain extent until 2 weeks after surgery, even though weight was borne on the operated leg and active ankle joint motion exercise was performed as much as possible during the early postoperative period. Therefore, it is necessary to use the IPC more than 2 weeks after surgery because thrombogenesis at POD 14 did not significantly decrease compared with that at POD 7, although Dahl et al.4 reported that it was necessary to be aware of the possibility of asymptomatic DVT during the first week after surgery. Postoperative swelling of the thigh, as measured by COT, was reduced earlier in the calf-thigh pump group than in the plantar pump group. Based on this result, it appears that compression that includes the entire leg is effective for reducing thigh swelling. However, in this study, there were no significant differences in D-dimer levels, and the reason may be that the two devices had equivalent effects. The advantage of the plantar pump was that it exerted higher pressure than the calf-thigh pump, whereas the calf-thigh pump provided compression over a wider area. We used two commercial devices, but it may be necessary to compare the device using the same amount of pressure or the same areas to confirm the advantage of one type of pump over the other. Several reports10,11 have suggested that IPC has some effect beyond its mechanical factors. Santori et al.11 re-
M. Fujisawa et al.: Calf-thigh pumping after THA
ported that the effects of the A-V Impulse System were not limited to its physical action, and that it had the effect of activating the fibrinolytic system by stimulating vascular endothelial cells. Liu et al.,10 using rat IPC models, investigated how the rapid increase in venous velocity induced by IPC produced a strong shear stress to the vascular endothelium, which in turn stimulated increased release of nitric oxide, thereby causing systemic vasodilatation. Therefore, the reducted swelling of the thigh might be due to vasodilatation caused by shear stress to the thigh.
Conclusions The results of this study, based on D-dimer levels, suggest that the calf-thigh pump is as effective a device for reducing thrombogenesis after THA as the plantar pump. In addition, the calf-thigh pump effectively reduces swelling of the thigh during the early stage following THA.
References 1. Bongard O, Wicky J, Peter R, et al. D-dimer plasma measurement in patients undergoing major hip surgery: use in the prediction and diagnosis of postoperative proximal vein thrombosis. Thromb Res 1994;74:487–93. 2. Bradley JG, Krugener GH, Jager HJ. The effectiveness of intermittent plantar venous compression in prevention of deep venous thrombosis after total hip arthroplasty. J Arthroplasty 1993;8:57– 61. 3. Cofrancesco E, Cortellaro M, Corradi A, et al. Coagulation activation markers in the prediction of venous thrombosis after elective hip surgery. Thromb Haemost 1997;77:267–9. 4. Dahl OE, Gudmundsen TE, Haukeland L. Late occurring clinical deep vein thrombosis in joint-operated patients. Acta Orthop Scand 2000;71:47–50. 5. Elliott CG, Dudney TM, Egger M, et al. Calf-thigh sequential pneumatic compression compared with plantar venous compression to prevent deep-vein thrombosis after non-lower extremity trauma. J Trauma 1999;47:25–32. 6. Fordyce MJF, Ling RSM. A venous foot pump reduces thrombosis after total hip replacement. J Bone Joint Surg Br 1992;74:45–9. 7. Fujiwara A, Ogata K, Hara M. The use of venous foot pump after total knee arthroplasty: an experimental study. Seikeigeka to Saigaigeka (Orthopedics and Traumatology) 1998; 47:370–3 (in Japanese). 8. Gardner AMN, Fox RH. The venous pump of the human footpreliminary report. Bristol Med Chir J 1983;98:109–12. 9. Hooker JA, Lachiewicz PF, Kelley SS. Efficacy of prophylaxis against thromboembolism with intermittent pneumatic compression after primary and revision total hip arthroplasty. J Bone Joint Surg Am 1999;81:690–6. 10. Liu K, Chen LE, Seaver AV, et al. Intermittent pneumatic compression of legs increases microcirculation in distant skeletal muscle. J Orthop Res 1999;17:88–95. 11. Santori FS, Vitullo A, Stopponi M, et al. Prophylaxis against deep-vein thrombosis in total hip replacement: comparison of heparin and foot impulse pump. J Bone Joint Surg Br 1994;76: 579–83.
M. Fujisawa et al.: Calf-thigh pumping after THA 12. Stannard JP, Harris RM, Bucknell AL, et al. Prophylaxis of deep venous thrombosis after total hip arthroplasty by using intermittent compression of the plantar venous plexus. Am J Orthop 1996;25:127–34. 13. Warwick D, Harrison J, Glew D, et al. Comparison of the use of a foot pump with the use of low-molecular-weight heparin for the prevention of deep-vein thrombosis after total hip replacement: a prospective, randomised trial. J Bone Joint Surg Am 1998;80: 1158–66. 14. Westrich GH, Sculco TP. Prophylaxis against deep venous thrombosis after total knee arthroplasty: pneumatic plantar compres-
811 sion and aspirin compared with aspirin alone. J Bone Joint Surg Am 1996;78:826–34. 15. Westrich GH, Specht LM, Sharrock NE, et al. Pneumatic compression hemodynamics in total hip arthroplasty. Clin Orthop 2000;372:180–91. 16. Wilson NV, Das SK, Kakkar VV, et al. Thrombo-embolic prophylaxis in total knee replacement: evaluation of the A-V Impulse System. J Bone Joint Surg Br 1992;74:50–2. 17. Woolson ST. Intermittent pneumatic compression prophylaxis for proximal deep venous thrombosis after total hip replacement. J Bone Joint Surg Am 1996;78:1735–40.
Effect of calf-thigh intermittent pneumatic compression device after total hip arthroplasty: comparative analysis with plantar compression on the effectiveness of reducing thrombogenesis and leg swelling Motoyuki Fujisawa, Masatoshi Naito, Isao Asayama, Taichi Kambe, and Kei Koga Department of Orthopaedic Surgery, Fukuoka University School of Medicine, 45-1 Nanakuma, Johnan-ku, Fukuoka 814-0180, Japan
Abstract The purpose of this study was to evaluate the efficacy of two intermittent pneumatic compression devices as prophylaxis against intravascular coagulation and leg swelling following total hip arthroplasty. We studied 121 patients by assessing thrombogenesis using the D-dimer level before and after total hip arthroplasty. In addition, the patients’ postoperative swelling was evaluated by measuring the thigh and lower leg circumference. Altogether, 58 patients were assigned to the calf-thigh pneumatic compression group, and the other 63 were assigned to the plantar compression group; the two pneumatic compression devices were compared to evaluate which was more effective for reducing thrombogenesis. At 7 days postoperatively, the mean D-dimer levels of the calfthigh compression group and the plantar compression group were 8.86 and 9.26 µg/ml, respectively. There was no significant difference (P ⫽ 0.697) between the two groups. However, the increased ratio of the circumference of the thigh, which was compared after arthroplasty, averaged 1.22% in the calfthigh compression group and 3.19% in the plantar compression group, which was significantly different (P ⬍ 0.01). Calf-thigh pneumatic compression was found to be more effective than plantar compression for reducing thigh swelling during the early postoperative stage. Key words Deep vein thrombosis · Intermittent pneumatic compression · Calf-thigh pneumatic compression
Introduction Ever since Gardner and Fox8 described a physiological pumping mechanism in the foot and the venous foot pump for preventing deep vein thrombosis (DVT) there have been numerous studies documenting the safety, inexpensiveness, and effectiveness of intermittent pneumatic compression (IPC) for preventing DVT after
Offprint requests to: M. Fujisawa Received: April 9, 2003 / Accepted: July 11, 2003
hip2,6,12,13 and knee7,14,16 arthroplasties. Most of these authors described the results obtained when the foot pump was used. In the meantime, Elliott et al.5 carried out a comparison of the calf-thigh pump with the plantar pump, exploring the possibility of preventing DVT after trauma. They conducted their study using ultrasonography and reported a lower incidence of DVT in the calf-thigh pump group. In reports on the use of the calf-thigh pump after total hip arthroplasty (THA), the prevalence of proximal DVT was reported to be 6% by Woolson17 and 3.8% by Hooker et al.9 The effect of the calf-thigh pump seemed similar to that of the plantar pump, with the incidence of DVT after plantar pump use reported as 3.3% by Bradley et al.2 Few reports, however, have precisely compared the effect of the calf-thigh pump and the plantar pump after THA. The optimal characteristics of these pumps for reducing DVT after THA have not been established. Westrich et al.15 evaluated seven pneumatic compression devices, including the plantar and calf-thigh pumps. They reported that calf and foot and calf pneumatic compression produced the greatest increase in peak venous velocity, whereas the calf-thigh pump produced the greatest increase in venous volume. However, their examination was performed on only 10 patients, and the results of their venous velocity and volume measurements varied widely, which weakens the validity of their results. Therefore, we compared the calf-thigh pump with the plantar pump to evaluate the effectiveness of reducing thrombogenesis and leg swelling after 121 THAs.
Materials and methods A series of 121 patients who had undergone THA were randomly allocated in the order in which they had been hospitalized: 58 patients in the calf-thigh pump group
808
M. Fujisawa et al.: Calf-thigh pumping after THA
Table 1. Specifications of two intermittent pneumatic compression devices Device Calf-thigh pump (Medomer) Foot pump (A-V impulse system)
Chamber
Pressure (mmHg)
Cycle time (s)
Inflation time (s)
2
20–80
14
3.1
1
120–160
20
0.4
who were fitted with the Medomer Automatic Air Massager (Nitto Kohki, Tokyo, Japan) and 63 patients in the plantar pump group who were fitted with the A-V impulse system (Orthofix Vascular Novamedix, Andover, UK). These two IPC devices are different with respect to the number of chambers, air pressure, cycles of inflation, and inflation times (Table 1). The exclusion criteria caused any patients with a history of DVT, pulmonary embolism, congestive heart failure, venous insufficiency, or the presence of a malignant tumor to be excluded from the study. Informed consent was obtained from all patients. All 121 arthroplasties were performed by the same surgeon. The procedures were done with the patient in the lateral decubitus position under epidural anesthesia, with implantation of the uncemented acetabular shell and femoral stem (VerSys Prosthesis, Zimmer). We assayed the D-dimer to evaluate intravascular coagulation preoperatively and again on days 7, 14, and 21 postoperatively. The D-dimer testing was performed by latex immunoassay. We also measured the circumferences of the thigh and lower leg to evaluate postoperative swelling of the legs. The circumference of the thigh (COT) was measured at a point 10 cm above the upper pole of the patella, and the circumference of the lower leg (COL) was measured at the widest point of the lower leg. The COT and COL of the bilateral legs were marked on the skin with an indelible marker preoperatively. We took the measurements at 6 a.m. on the day of the operation and again at the same time on days 3, 7, 14, and 21 postoperatively. Each of the measurement values was the median of three measurements; they were compared to the preoperative measurements (taken as 100%). All patients in both groups underwent the same postoperative management. Immediately after the operation, all patients were fitted with either a plantar pump or a calf-thigh pump. The fitting time for both groups was 4 h per day over a period of 21 days in all patients based on the report7 from our department indicating that there was no significant difference in the D-dimer level after arthroplasty for patients who were fitted with an IPC 4 h per day and those who were fitted 18 h per day. All patients began to walk on the third day after
Table 2. Demographic data for patients in the two groups Parameter
Calf-thigh pump
Plantar pump
No. Male : female Age (years), mean and range Duration of operation (min), mean and range Body mass index, mean and range
58 8 : 50 61.36 (20–84) 94.7 (55–180) 23.6 (16.1–39.4)
63 10 : 53 62.21 (41–86) 95.5 (55–225) 24.1 (18.1–37.0)
surgery and were able to bear nearly their full weight on the operated leg. They were discharged 3 weeks after the operation. No anticoagulant drugs or antiembolism stockings were used. Statistical analyses of the patient data were performed using the chi-square test for gender and Student’s t-test for age, duration of the operation, and body mass index. The D-dimer values and the circumference measurements were analyzed using Student’s t-test for a comparison of the two groups. The paired t-test was used to compare the differences between weeks.
Results All 121 patients completed the trial. The two groups were well matched with regard to gender, age, leg operated on, duration of the operation, and body mass index (Table 2). There were no significant differences in baseline characteristics between the two groups. None of the 121 patients developed the typical symptoms of DVT or pulmonary embolism. D-dimer Preoperatively, the D-dimer levels averaged 0.94 µg/ml in the calf-thigh pump group and 0.88 µg/ml in the plantar pump group (Table 3). On postoperative day (POD) 7, the mean D-dimer levels were 8.86 µg/ml in the calf-thigh pump group and 9.26 µg/ml in the plantar pump group. The D-dimer levels of both groups showed significant increases over their preoperative values (P ⬍
M. Fujisawa et al.: Calf-thigh pumping after THA
809
Table 3. Postoperative changes in D-dimer levels: calf-thigh pump versus plantar pump groups Change in D-dimer levels (µg/ml) Days after operation
Calf-thigh pump
Before operation 7 14 21
0.94 8.86 8.99 5.81
⫾ 1.38 ⫾ 6.09 ⫾ 6.67 ⫾ 4.75
* NS *
Plantar pump
P
⫾ 0.71 ⫾ 4.87 ⫾ 4.65 ⫾ 3.09
NS NS NS NS
0.88 9.26 8.92 5.33
* NS *
* ⬍ 0.01
Fig. 1. Curves (circles, calf-thigh pump; diamonds, plantar pump group) show changes in the circumference of the thigh (COT). Reduction of Postoperative swelling was reduced earlier in the calf-thigh pump group than in the plantar pump group. The average COT of the calf-thigh pump group was significantly smaller (by 1.98%) than that of the plantar pump group at postoperatively day 7 (P ⬍ 0.01)
Fig. 2. Curves (circles, calf-thigh pump; diamonds, plantar pump group) show changes in the circumference of the lower leg (COL). The COL of the calf-thigh pump group was smaller than that of the plantar pump group. The reduction in the plantar pump group from days 14 to 21 was significant (P ⬍ 0.01)
0.0001). However, there were no significant differences from POD 7 to POD 14 in either group. The mean Ddimer level was significantly decreased from POD 14 to POD 21 in both groups (P ⬍ 0.0001). No statistically significant differences were observed between the two groups in regard to mean D-dimer levels for any assay date.
and from POD 7 to POD 14 (2.11%) (P ⬍ 0.001). The plantar pump group showed deterioration on POD 7 compared to that on POD 3. This was followed by a significant reduction (3.68%) (P ⬍ 0.001) from POD 7 to POD 14. Thus, the postoperative swelling in the calf-thigh pump group was reduced earlier than in the plantar pump group. The COL of the operated legs (Fig. 2) was smaller in the calf-thigh pump group than in the plantar pump group on each day measurements were taken, but the difference between the two groups was not significant. The COL of the operated legs from POD 14 to POD 21 after the operation in the plantar pump group was significantly reduced (P ⬍ 0.01).
Postoperative swelling of lower extremity The results of the circumference measurements of the thighs of the operated legs showed no significant differences at POD 3 (Fig. 1). However, by POD 7, the COT in the calf-thigh pump group was significantly smaller (by 1.98%) than that of the plantar pump group (P ⬍ 0.01). On PODs 14 and 21, no significant differences were seen between the two groups. In terms of the timedependent changes of the postoperative swelling reduction, the calf-thigh pump group showed a significant reduction from POD 3 to POD 7 (1.76%) (P ⬍ 0.01)
Discussion Studies evaluating DVT once depended on venography2,6,13,16 but have recently employed ultrasonogra-
810
phy.5,9,12,14,17 We assayed the D-dimer level to evaluate intravascular coagulation preoperatively and postoperatively because the procedure is objective, has greater reliability, and is less invasive and laborintensive than venography or venous ultrasonography. The assay can be done by the usual blood collection method. D-dimer is a degradation product that occurs when a thrombus is dissolved by the fibrinolytic system. This activation occurs after the solidification stage. Thus, an elevated D-dimer level in the blood indicates the existence of venous thrombosis. A high value for the D-dimer concentration has been reported to show a strong correlation with DVT results obtained by venography3 or venous ultrasonography.1 On day 7 after arthroplasty in a previous study conducted by our institute,7 the D-dimer level in patients using the foot pump was 10.5 µg/ml, whereas in patients using no pump it was significantly elevated (to 16.5 µg/ ml). In the present study, we found that the D-dimer levels were less than 10 µg/ml in both the plantar and calf-thigh pump groups, and there were no significant differences between the two groups in regard to sequential D-dimer values. These results suggest that the calfthigh pump is similar to the plantar pump in terms of its effectiveness in reducing thrombogenesis after THA. In addition, the D-dimer remained higher for 2 weeks after THA but decreased significantly thereafter. These results suggest that thrombus existed to a certain extent until 2 weeks after surgery, even though weight was borne on the operated leg and active ankle joint motion exercise was performed as much as possible during the early postoperative period. Therefore, it is necessary to use the IPC more than 2 weeks after surgery because thrombogenesis at POD 14 did not significantly decrease compared with that at POD 7, although Dahl et al.4 reported that it was necessary to be aware of the possibility of asymptomatic DVT during the first week after surgery. Postoperative swelling of the thigh, as measured by COT, was reduced earlier in the calf-thigh pump group than in the plantar pump group. Based on this result, it appears that compression that includes the entire leg is effective for reducing thigh swelling. However, in this study, there were no significant differences in D-dimer levels, and the reason may be that the two devices had equivalent effects. The advantage of the plantar pump was that it exerted higher pressure than the calf-thigh pump, whereas the calf-thigh pump provided compression over a wider area. We used two commercial devices, but it may be necessary to compare the device using the same amount of pressure or the same areas to confirm the advantage of one type of pump over the other. Several reports10,11 have suggested that IPC has some effect beyond its mechanical factors. Santori et al.11 re-
M. Fujisawa et al.: Calf-thigh pumping after THA
ported that the effects of the A-V Impulse System were not limited to its physical action, and that it had the effect of activating the fibrinolytic system by stimulating vascular endothelial cells. Liu et al.,10 using rat IPC models, investigated how the rapid increase in venous velocity induced by IPC produced a strong shear stress to the vascular endothelium, which in turn stimulated increased release of nitric oxide, thereby causing systemic vasodilatation. Therefore, the reducted swelling of the thigh might be due to vasodilatation caused by shear stress to the thigh.
Conclusions The results of this study, based on D-dimer levels, suggest that the calf-thigh pump is as effective a device for reducing thrombogenesis after THA as the plantar pump. In addition, the calf-thigh pump effectively reduces swelling of the thigh during the early stage following THA.
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