Abstract
The aim of this study is to evaluate whether computer-assisted navigated TKA reduces perioperative blood loss. Patients were randomly divided into 2 groups and underwent either a conventional TKA (n = 40) or a TKA with computer-assisted navigation (n = 40). Perioperative blood loss was evaluated by laboratory parameters, postoperative drain output and number of required transfusions. Change in hemoglobin concentration and in hematocrit levels was similar. Also, there was no statistically significant difference in drain output and in the number of transfused units. The results of this study showed that TKA with computer-assisted navigation is similar to the conventional TKA regarding perioperative hemorrhage.
Keywords: TKA, Computer-assisted navigation, Blood loss, Hemorrhage
1. Introduction
Total knee arthroplasty (TKA) is associated with considerable blood loss due to extensive soft tissue releases and osteotomies and therefore blood transfusion is required in many cases.1, 2, 3 Allogenic blood transfusion is related to several adverse events such as infection transmission and fluid overload and given the aging population undergoing joint replacement the risk for development of these complications is significantly high.4 Several measures for reduction in TKA perioperative hemorrhage have been proposed including minimally invasive methods, use of a tourniquet, sealing of the femoral canal, antifibrinolytic agents and flexed position of the knee during the operation.
Although computer-assisted surgery (CAS) was initially introduced to improve TKA outcomes by a more accurate prosthesis positioning and better mechanical alignment, a secondary advantage of this method may be the reduced perioperative blood loss. This is mainly because femoral canal breaching which is believed to be one of the main causes of hemorrhage during TKA is not needed.5, 6, 7 However, the success rate of these reported benefits of the navigated technique widely varies since it depends on many factors such as the good knowledge of the computer software and the familiarization of the surgical team with the computer-assisted navigation method.9 Several studies have been conducted in order to evaluate the perioperative blood loss of CAS TKA, showing mixed results. Although the avoidance of femoral canal's breaching and the minimal soft tissue release decrease blood loss, some argue that prolongation of the operating time along with the insertion of bicortical tracker pins onto the tibia and femur may negate this benefit.4,6,10,11 In 2015 Han et al. published a meta-analysis in which they included 12 studies that compared blood loss between computer-assisted navigated TKA and conventional TKA.12 The authors reported that the change in hemoglobin concentration before and after surgery was less for the CAS group. Moreover, they found that blood loss via drainage and the calculated blood loss were lower with computer navigation than with conventional TKA. However, they did not find any significant difference regarding the requirements for transfusion, so the authors highlighted that the results of their study must be interpreted with caution regarding the clinical significance of their findings.
Our hypothesis is that computer-assisted navigation technique influences perioperative blood loss in TKA and in order to test this hypothesis we compared the blood loss between the conventional and the computer-assisted navigation technique for TKA.
2. Methods
2.1. Patients
This is a prospective study enrolling 80 patients who underwent TKA over a 2-year period. Patients were randomly allocated by draw to undergo either a conventional TKA (Conventional group, n = 40), or a TKA with computer assisted navigation (CAS group, n = 40). An informed consent was obtained from every patient, while the study was approved by the Institutional Review Board of the hospital. Recorded variables included age, sex, BMI, Charlson Comorbidity index (CCI), duration of surgery, laboratory parameters pertaining to hemorrhage, volume of collected blood in drains during the first 48 h, and the number of required transfusions. Patients on certain anticoagulants such as clopidogrel or aspirin that could not be discontinued during the perioperative period were excluded from the study. For the evaluation of blood loss 3 different parameters were assessed: postoperative change in relevant laboratory markers (hematocrit level and hemoglobin concentration) immediately after surgery and on the following 5 postoperative days, postoperative blood drainage during the first 48 h, and number of required transfusions intraoperatively and for the first 5 postoperative days. The threshold for transfusion was hemoglobin level less than 9 g/dL according to the hospital's protocol.
2.2. Surgery
Αll operations were performed under tourniquet by the same surgeon who had been using this navigation system for the past 5 years. A standard median incision and a medial parapatellar approach was used in all patients. The tourniquet was used until cementation at a pressure of 250 mmHg. For the TKA with computer-assisted navigation, the Orthopilot (by Aesculap) system was used. During the conventional method a drill hole on the femur for the insertion of the intramedullary instrumentation was done and at the end of the surgery this hole was plugged with bone form the chamfer bone cuts. For the patients in the computer-assisted navigation group the Columbus knee (by Aesculup) was used, while for the patients in the control group the Advance (by Wright) knee was used. Postoperatively all patients received a daily dose of LMWH for the first month and a daily dose of 100 mg aspiring for the following two weeks.
2.3. Statistical analysis
Statistical analysis included descriptive statistics of patients' demographics and laboratory parameters. The comparisons between the 2 groups for various variables such as demographics, laboratory parameters, drain output and number of transfusions were performed using the non-parametric Mann-Whitney U test for continuous variables and the chi-squared test for categorical variables. Moreover a linear regression analysis was performed for an adjusted analysis. On this analysis, the effect of the method of TKA (i.e. conventional or with navigation) on perioperative blood loss was adjusted for certain variables (age, sex, BMI, CCI, duration of surgery). Statistical significance for all tests was set at p value > 0.05. Statistical analysis was performed using the STATA software.
3. Results
The mean age of the patients who underwent TKA with computer-assisted navigation was 68.2 ± 6.4 years, ranging from 55 to 83, while the mean age of patients in the control group was 67.3 ± 12.6 years, ranging from 50 to 79. The study included 53 female patients (26 in the CAS group and 27 in the conventional group) and 27 male patients (14 in the CAS group and 13 in the conventional group). The duration of surgery was significantly longer for the CAS group (p = 0.01) Baseline characteristics of the study population are summarized in Table 1.
Table 1.
Demographics, preoperative laboratory values and duration of surgery.
| CAS group (n = 40) | Conventional group (n = 40) | P value | |
|---|---|---|---|
| Age (years) | 68.2 ± 6,4 (55–83) | 67.3 ± 12,6 (50–79) | 0.46 |
| Male gender (%) | 14 (35.0%) | 13 (32.5%) | 0.81 |
| Right side operated (%) | 21 (52.5%) | 18 (45.0%) | 0.50 |
| CCI | 2.2 ± 1.8 (0–3) | 3.1 ± 1.7 (0–5) | 0.18 |
| BMI (kg/m2) | 29.3 ± 3.1 (22.3–38) | 30.4 ± 2.9 (19.7–39.1) | 0.75 |
| Duration of surgery (minutes) | 90 ± 11 (78–115) | 75 ± 9 (60–85) | 0.01 |
| Preoperative hematocrit (vol%) | 41.2 ± 2,3 (33–50.1) | 39.6 ± 6.6 (32.3–49) | 0.63 |
| Preoperative hemoglobin (g/dL) | 13.5 ± 1.1 (10.3–16.1) | 13.0 ± 2.0 (10.8–16.4) | 0.68 |
Values are mean ± SD (range) or n (%).
Abbreviations: CAS, computer assisted surgery; BMI, body mass index; CCI, Charlson comorbidity index.
The postoperative change in the assessed laboratory parameters (hematocrit levels and hemoglobin concentration) at various perioperative times are presented in Table 2, Table 3. The hematocrit and hemoglobin levels showed a continuous decrease immediately after surgery and on the 1st, 2nd and 5th postoperative days in both groups. Although on the 30th postoperative day both hematocrit levels and hemoglobin conentration had been increased, they did not reach the preoperative levels. The change in hematocrit levels in the CAS group was lower than in the conventional group at all times except for the 5th postoperative day. However, change in hematocrit level was significantly lower in the CAS group only immediately after surgery (p = 0.02), while at all other times there was no statistically significant difference between the 2 groups (p > 0.05). Similarly, although postoperative change in hemoglobulin concentration in the CAS group was lower than in the conventional group at all times, no statistically significant difference was found at any of these perioperative times (p > 0.05). Likewise, when the evaluation of the effect of the TKA method on perioperative blood loss was adjusted for certain variables (BMI, sex, age, CCI, duration of surgery) using linear regression analysis, TKA with computer assisted navigation was also not correlated with a lower change in hematocrit levels (R squared = 0.03, p = 0.08) and hemoglobilin concentration (R squared = 0.01, p = 0.23). Results of linear regression analysis are summarized in Table 4.
Table 2.
Postoperative change in hematocrit level (vol %) per different times of blood sampling.
| Time of blood sampling | CAS group | Conventional group | P value |
|---|---|---|---|
| Immediately after surgery | 4.8 ± 0.22 | 6.9 ± 3.2 | 0.02 |
| 1st day postoperatively | 7.6 ± 1.1 | 7.9 ± 2.3 | 0.05 |
| 2nd day postoperatively | 9.4 ± 1.2 | 9.6 ± 1.3 | 0.09 |
| 5th day postoperatively | 9.8 ± 1.7 | 9.7 ± 2.6 | 0.96 |
| 30th day postoperatively | 3.5 ± 0.3 | 3.9 ± 1.3 | 0.16 |
Abbreviations: CAS, computer assisted surgery.
Table 3.
Postoperative change in hemoglobin concentration (gr/dL) per different times of blood sampling.
| Time of blood sampling | CAS group | Conventional group | P value |
|---|---|---|---|
| Immediately after surgery | 1.1 ± 0.22 | 1.2 ± 0.23 | 0.08 |
| 1st day postoperatively | 2.6 ± 0.9 | 2.9 ± 1.3 | 0.68 |
| 2nd day postoperatively | 3.1 ± 1.1 | 3.3 ± 1.4 | 0.09 |
| 5th day postoperatively | 3.3 ± 1.3 | 3.7 ± 0.9 | 0.16 |
| 30th day postoperatively | 1.2 ± 0.3 | 1.4 ± 0.8 | 0.66 |
Abbreviations: CAS, computer assisted surgery.
Table 4.
Linear regression analysis of the association between change in hematocrit levels and hemoglobin concentration with demographics, duration of surgery and method of TKA (i.e. conventional or with navigation).
| Multivariate analysis | Change in hematocrit |
Change in hemoglobulin |
||||||
|---|---|---|---|---|---|---|---|---|
| R2 | β | 95% CI | p-Value | R2 | β | 95% CI | p-Value | |
| BMI | 0.02 | −0.33 | [− 0.43, 0.81] | 0.22 | 0.02 | −0.13 | [− 0.17, 0.19] | 0.15 |
| Sex | 0.25 | 0.51 | [ − 0.32, 1.05] | 0.06 | 0.25 | 0.21 | [ − 0.03, 1.03] | 0.07 |
| TKA method | 0.03 | 0.37 | [ − 0.10, 0.88] | 0.08 | 0.01 | 0.13 | [ − 0.20, 1.25] | 0.23 |
| Age | 0.01 | 0.42 | [− 0.27, 1.12] | 0.23 | 0.01 | 0.54 | [− 0.37, 1.24] | 0.22 |
| Duration | 0.29 | −0.43 | [− 0.48, −0.40] | 0.003 | 0.28 | −0.10 | [− 0.12, −0.02] | 0.004 |
| CCI | 0.03 | −0.23 | [− 0.11, 0.24] | 0.08 | 0.03 | −0.08 | [− 0.16, 0.01] | 0.07 |
Abbreviations: TKA, total knee arthroplasty; BMI, body mass index; CCI, Charlson comorbidity index.
Data on blood transfusions for the patients in both groups at different perioperative times (intraoperatively, 1st, 2nd, 3rd, 4th and 5th postoperative day) are presented in Table 5. There was no statistically significant difference regarding the number of transfusions between the 2 groups at any of the assessed perioperative times. The multivariate linear regression further confirmed that the total number of transfusions was not affected by the method (i.e. conventional or with computer-assisted navigation) of TKA (R squared = 0.02, p = 0.16; Table 4). Last, data on drain output was available only for 22 patients from the conventional group (Fig. 1). The average volume of collected blood in drains during the first 48 h was 933.78 ± 317.87 ml for the CAS group and 892.73 ± 305.15 ml for the conventional group. These 2 vol of collected blood between the 2 groups were statistically similar (p = 0.62).
Table 5.
Number of blood transfusions in patients of the 2 groups intraoperatively and on the first 5 postoperative days.
| Time | CAS group | Conventional group | P value |
|---|---|---|---|
| Intraoperatively | 0.83 ± 0.11 | 0.95 ± 0.17 | 0.65 |
| 1st day postoperatively | 0.08 ± 0.05 | 0.13 ± 0.12 | 0.31 |
| 2nd day postoperatively | 0.10 ± 0.05 | 0.22 ± 0.08 | 0.27 |
| 3d day postoperatively | 0.08 ± 0.04 | 0.09 ± 0.06 | 0.96 |
| 4th day postoperatively | 0.08 ± 0.04 | 0.09 ± 0.06 | 0.96 |
| 5th day postoperatively | 0.05 ± 0.03 | 0.04 ± 0.04 | 0.97 |
Abbreviations: CAS, computer assisted surgery.
Fig. 1.
The blood loss distribution through drainage during the first 48 h after surgery (left: CAS group, right: Conventional group).
4. Discussion
The results of this study support that there is no significant difference in the amount of blood loss between TKA with computer-assisted navigation and the conventional method. Although hematocrit and hemoglobin in the computer-assisted surgery group were higher than those of the conventional group at almost all perioperative times, the only significant difference was found for the postoperative change in hematocrit levels immediately after surgery. Moreover, no statistically significant difference was found regarding the number of transfusions and the postoperative drain output between the 2 groups.
Certain studies have reported a significant decrease in blood loss in favor of TKA with computer-assisted navigation over the conventional method.13, 14, 15 Conteduca et al. conducted a prospective randomized study in 100 patients, who underwent TKA either with computer-assisted navigation or with the conventional technique.4 The authors compared the intraoperative blood loss between these two groups and they reported a statistically significant difference between the CAS and the conventional group. The average blood loss was 1974 ml and 1677 ml for the conventional and the CAS groups respectively. Based on their results the authors recommended computer-assisted surgery, especially for anemic patients. However, the postoperative blood loss which was found to be considerable in our study was not evaluated in that study. Similarly, Chauchan et al. compared CAS with conventional TKA in a total of 70 patients and reported a decrease in blood loss and an improved alignment for the CAS group.8 In a recent study Licini et al. compared CAS versus conventional TKA in 100 patients and found that CAS group demonstrated less drain output and hemoglobin change after surgery.16 Conversely, according to some other studies there is no difference regarding blood loss between the navigated TKA and the conventional TKA.7,17 Singla et al. in their study reported no significant difference in both total and hidden blood loss between the CAS and the conventional technique.18 The results of our study agree with the latter studies which dispute the reduced blood loss in the TKA with computer-assisted navigation.
Decrease in blood loss with the computer-assisted navigation method is mainly attributed to the fact that this method avoids breaching the intramedullary canal of the femur. Although TKA with computer-assisted navigation minimizes bleeding from the femoral canal, it still requires the insertion of two pins in the shafts of femur and tibia, which may be a potential cause for additional blood loss.17 Moreover, TKA with computer-assisted navigation is linked with increased duration of surgery. Therefore the mean tourniquet time may be longer for a surgery with the computer-assisted navigation technique. Although Alcelik et al. in his meta-analysis13 reported a significantly higher mean operative time (32 min) for joint replacement with computer-assisted navigation, there is a large body of evidence supporting that surgeon's experience on computer-assisted navigation techniques may considerably reduce the duration of surgery.19,20 Prolonged anoxia due to longer tourniquet time has been associated with activation of the antithrombin III and protein C pathways.21 This can result in further post-tourniquet bleeding which may also negate the advantage of not opening the femoral canal for the navigated TKA18,22
There are certain limitations of this study that must be addressed. Although the relatively small sample size of this study is a certain limitation, there are not many studies in the literature evaluating perioperative hemorrhage associated with CAS TKA in a large population. Second, another limitation of the study is that the methods that were used for the evaluation of blood loss do not accurately calculate and quantify the amount of blood loss. However, the combined use of our assessed parameters can indirectly estimate perioperative hemorrhage.
The primary hypothesis that computer-assisted navigation method reduces blood loss during TKA was not confirmed by the results of our study. We demonstrated that there is no significant difference in total blood loss between the TKA with computer-assisted navigation or the conventional method. The postoperative change in hematocrit levels and hemoglobin concentration (except for change in hematocrit levels immediately after surgery), the number of vials transfused and the mean blood loss through drains were similar for both the conventional method and the computer-assisted navigation. Considering the longer duration for the CAS technique and its high cost, this study questions the adoption of this method as a measure for reduction in perioperative blood loss.
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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