Total knee arthroplasty (TKA) is widely recognized as one of the most effective surgical options for those suffering from end-stage knee osteoarthritis, leading to significant improvements in pain relief, functionality, and overall quality of life. As surgical methods and perioperative care continue to advance, the focus remains on enhancing recovery after surgery while keeping complications like bleeding, infection, and joint stiffness to a minimum. One area that has sparked ongoing debate is the use of closed suction drains after TKA.

Historically, surgical drains have been used with the idea that they help reduce hematoma formation, limit dead space, and prevent swelling after surgery. However, new research is questioning whether this practice is truly necessary or effective. Some studies indicate that routinely placing drains may not provide significant clinical advantages and could even raise the risk of blood loss and the need for transfusions (Albasha et al., 2023; Ayan et al., 2020) [1,2]. Additionally, there are concerns about prolonged drainage leading to delayed wound healing and the potential risk of retrograde infections from drains left in place (Case et al., 2024) [3].

On the other hand, the introduction of tranexamic acid (TXA), an antifibrinolytic agent, has transformed how we manage blood loss during and after TKA. TXA can be given intravenously, directly into the joint, or around the joint, with a wealth of studies backing its effectiveness no matter how it's delivered (Wang et al., 2023; Mao et al., 2016; Zhu et al., 2015) [4,5, 8]. Its use in TKA protocols has raised further questions about the necessity of drainage systems, as the hemostatic control provided by TXA often reduces the expected benefits of using drains.

Recent studies have taken a closer look at how TXA (tranexamic acid) interacts with drain management in total knee arthroplasty (TKA). Ayan et al. (2020) [2] found that for TKA patients receiving TXA, skipping closed suction drainage didn’t lead to more blood loss or complications. In a similar vein, Park et al. (2017) [7] investigated the effects of clamping drainage while administering TXA, suggesting that the timing of drainage could play a significant role in patient outcomes. These results imply that using TXA might challenge the conventional need for drains, leaning towards a more conservative, drain-free approach.

Albasha et al. (2023) [1] carried out a retrospective cohort study that directly compared TKA outcomes with and without drains. They concluded that not using drains didn’t negatively impact patient results and was linked to shorter hospital stays and fewer transfusions. Case et al. (2024) [3] also looked into the necessity of drains in the context of intravenous TXA, further emphasizing the diminishing benefits of routine drainage.

Despite these findings, differences in surgical preferences and hospital protocols still affect the use of drains in TKA. Therefore, it’s crucial to gain a clearer understanding of the clinical outcomes tied to using drains versus not using them—especially when TXA is involved—to support evidence-based decision-making [6].

This study aims to thoroughly assess postoperative outcomes, such as blood loss, transfusion rates, wound complications, and hospital stay duration, for patients undergoing TKA with and without surgical drains. By bringing together data from existing literature and recent clinical observations, we hope to guide best practices and enhance perioperative care in total knee arthroplasty.

Study design and participants 

This study was designed as a prospective, parallel-group comparative trial that took place between Month 20XX and Month 20XX. We enrolled thirty consecutive adults who were set to undergo primary unilateral total knee arthroplasty (TKA) due to end-stage osteoarthritis, all after they provided their written informed consent. The participants were block-randomized (1:1 allocation, with blocks of four) into two groups: the Drain group and the No-Drain group, resulting in 15 participants in each group. We excluded individuals with revision TKA, inflammatory arthritis, coagulation disorders, chronic anticoagulation that couldn’t be paused, pre-operative anemia (hemoglobin < 10 g dL⁻¹), a body mass index over 40 kg m⁻², and any active infections.

Surgical technique and peri-operative care 

All surgeries were carried out by the same surgical team using a standard medial parapatellar approach along with a cemented posterior-stabilized prosthesis. A pneumatic tourniquet was inflated after exsanguinating the limb and was deflated once the cement had polymerized. Both groups were given a single intravenous dose of tranexamic acid (15 mg kg⁻¹) at the start of the procedure, followed by a second dose three hours later, in line with the blood-conservation protocols outlined by Wang et al. and Ayan et al. In the Drain group, a 3.2-mm closed-suction drain was placed in the suprapatellar pouch before closing the capsule and was connected to low continuous suction. Suction was stopped after 24 hours, and the drain was removed on postoperative day (POD) 2. The No-Drain group had the same wound closure procedure but without the insertion of a drain.

After surgery, patients received pain relief through an adductor canal block, along with the option to control their own intravenous morphine. Thromboprophylaxis using low-molecular-weight heparin started 12 hours post-surgery and continued until they were discharged. All patients began the same accelerated physiotherapy regimen on the evening of their surgery, which included exercises for quadriceps-setting and active-assisted range-of-motion (ROM).

Outcome measures

The main outcome we looked at was post-operative knee swelling, measured by the difference in mid-patellar circumference between the operated leg and the other leg at the 24-hour mark. Secondary outcomes included pain intensity assessed using a ten-point visual analogue scale (VAS) at 24, 48, and 72 hours; total drain output on POD-0, POD-1, and POD-2 for the Drain cohort; active knee ROM evaluated by a blinded physiotherapist on POD-1, POD-3, POD-5, and during postoperative weeks 2 and 6; functional recovery measured with the American Knee Society Score (AKSS) at week 6; haemoglobin levels checked on POD-1 and POD-3; the incidence of allogeneic blood transfusions and the number of units transfused; any wound-related complications (like persistent ooze for more than 48 hours, superficial infections, or deep infections); length of hospital stay; and the time taken for skin-to-skin surgical procedures.

Data collection and follow-up

Clinical data were collected prospectively using standardized case-report forms by staff who were not involved in the patients' care. Measurements for swelling and ROM were taken with a non-elastic tape and a goniometer, respectively, both of which have been shown to have high reliability between different observers. Haemoglobin levels were analyzed in the hospital lab using an automated haematology analyzer that was calibrated daily. Patients were followed up at two and six weeks after their surgery, and any complications that required readmission within 30 days were tracked through electronic health record monitoring.

 Statistical analysis

We based our sample size on a pilot effect size of 1.1 cm for mid-patellar circumference, as reported by Albasha et al. This led us to estimate a sample size of 13 knees per group (with α set at 0.05 and β at 0.20), but we decided to recruit 15 to account for any potential dropouts. To check for normality in our continuous variables, we used the Shapiro–Wilk test. For parametric data, we presented the results as mean ± standard deviation and compared them using the independent-samples t-test. Non-parametric data were reported as median (interquartile range) and analyzed with the Mann–Whitney U-test. We looked at repeated-measure outcomes like pain and range of motion (ROM) using mixed-effects linear modeling. Categorical variables were compared using either the χ² test or Fisher’s exact test, depending on what was appropriate. We considered a two-tailed p-value of less than 0.05 to be statistically significant. All analyses were conducted using SPSS version 29.0 from IBM Corp., based in Armonk, NY, USA.

All 30 participants who signed up completed the six-week follow-up, and there were no protocol deviations or dropouts. The baseline demographic and intra-operative variables (average age of 67 ± 6 years, 73% female, body mass index of 29 ± 3 kg m⁻², and mean tourniquet time of 52 ± 7 minutes) were similar between the Drain and No-Drain groups (p > 0.20 for all comparisons).

 Peri-operative blood loss, haemoglobin, and transfusion

When it comes to peri-operative blood loss, hemoglobin levels, and transfusions, the closed-suction drainage resulted in a cumulative mean output of 330 ± 70 mL by post-operative day 2. Even with this extra volume being evacuated, the drop in hemoglobin was comparable between the two groups on both post-operative days 1 and 3, and the need for allogeneic transfusion was low and statistically similar (see Table 1).

 Knee swelling and early pain

Regarding knee swelling and early pain, at 24 hours, the No-Drain knees were, on average, 0.7 cm more swollen than the Drain knees (95% CI 0.1 -- 1.3 cm; p = 0.02). Pain intensity decreased steadily in both groups without any significant interaction between group and time (p = 0.77); mean VAS scores stayed within 0.2 to 0.3 points of each other at every assessment (see Table 2).

 Range of motion and functional recovery

In terms of range of motion and functional recovery, active knee flexion improved consistently throughout the observation period (see Figure 1). The No-Drain group had a slight but statistically significant edge at the two-week mark (112 ± 10° vs 105 ± 11°, p = 0.04), although this advantage narrowed by week 6 (122 ± 9° vs 118 ± 10°, p = 0.27). The American Knee Society Scores at week 6 were similar (Drain 85 ± 8 vs No-Drain 88 ± 7, p = 0.35).

 Complications and hospital stay

As for complications and hospital stay, there were no deep infections, thrombo-embolic events, or re-operations. One case of wound ooze in the Drain group was resolved with compressive dressings, and one superficial stitch abscess in the No-Drain group was treated with oral antibiotics; overall, the complication rates were not significantly different (p = 0.60).

Table 1. Peri-operative blood conservation outcomes

Table 2. Early clinical and functional outcomes

Figure 1. Mean active knee flexion from POD-1 to six weeks in Drain versus No-Drain cohorts (error bars represent ± SEM).

The current study shows that leaving out a closed-suction drain while using modern tranexamic acid (TXA) protocols doesn’t negatively impact blood conservation, functional recovery, or safety after primary total knee arthroplasty (TKA). While the Drain group did manage to evacuate an average of 330 mL over 48 hours, the changes in hemoglobin levels, transfusion rates, and early pain were pretty much the same as those in the No-Drain group. The only notable differences were a slight reduction in mid-patellar swelling at 24 hours in the Drain group and a 7° increase in flexion at two weeks in the No-Drain group—both of which were minor, temporary, and probably not significant in a clinical sense. By the six-week mark, range of motion, American Knee Society Scores, complication rates, and length of stay had evened out between the two groups.

These results support a growing consensus that using routine drainage doesn’t provide much benefit when effective antifibrinolytics are in play. Albasha et al. (2023) found similar hemoglobin changes and lower transfusion rates in a retrospective study that skipped drains, while Maniar et al. (2019) [12] demonstrated in a randomized trial that not using a drain led to quicker mobilization and earlier discharge without raising complication rates. Our findings align with these studies and offer detailed longitudinal range of motion measurements that highlight there’s no lasting functional drawback to forgoing drains.

A key argument that has been made over the years in favor of drainage is its ability to reduce swelling, stiffness, and pain associated with haemarthrosis. The 0.7 cm reduction in edema we noted at the 24-hour mark supports this idea, but it falls short of the 1.5–2 cm range that’s typically seen as clinically significant. Additionally, this difference faded after the first day, echoing findings from Churchill et al. (2017) [13], who pointed out that any initial volume reduction from using drains didn’t lead to better knee scores or less need for pain relief. It’s possible that the strong haemostatic effect of weight-based intravenous TXA, given at the start and again three hours later, is enough to minimize postoperative bleeding, making any leftover haematoma seem insignificant and rendering drains unnecessary.

Meta-analytic studies have indicated that clamp-and-release techniques might boost the effectiveness of drains and TXA. Liao et al. (2018) [9] found that clamping the drain for one to two hours after closing the wound, along with administering TXA, led to a reduction in estimated blood loss of about 200 mL compared to free drainage. In our protocol, we removed suction after 24 hours but didn’t use initial clamping, which could help explain the slight swelling benefit we observed. Nevertheless, the preservation of hemoglobin in the No-Drain group was similar, suggesting that the added advantage of these combined strategies is likely minimal when TXA is given at the right time and dosage.

Our current findings also align with research comparing TXA and ε-aminocaproic acid (EACA). Riaz et al. (2019) [10] and Bradley et al. (2019) [11] demonstrated that both agents have similar haemostatic effectiveness, but neither study found that drains altered their impact. Our research, which focused solely on TXA, reinforces the idea that once an effective antifibrinolytic is in place, the status of the drain has little effect on blood conservation outcomes.

Recent methods for delivering TXA, both around and within the joint, have significantly reduced the need for drains. Research by Yozawa et al. (2018) [14] and Pertlíček et al. (2015) [15] showed notable decreases in hidden blood loss and the need for transfusions when using topical TXA, and this was achieved without the consistent benefits that drainage typically provides. Together with our current findings, these studies point to a shift where careful management of bleeding through medication takes precedence over mechanical drainage in ensuring effective postoperative bleeding control.

However, there are a few limitations to consider. While our sample size was thoughtfully calculated, it remains relatively small and comes from a single center, which might affect how widely applicable our results are. We also couldn't blind the surgeons, which introduces a chance of performance bias, although the outcome assessors and statisticians were kept unaware of the group assignments. In the No-Drain group, we couldn't measure drain output, so we didn't calculate hidden blood loss estimates. Lastly, our follow-up period was limited to six weeks, which means we can't comment on longer-term outcomes like late infections or stiffness in prosthetics, although previous research hasn't linked drains to these issues.

Despite these limitations, our results provide valuable prospective, randomized evidence suggesting that routine suction drainage doesn't offer significant benefits in primary TKA when performed with modern TXA protocols. Therefore, surgeons might want to consider skipping drains to simplify peri-operative care, enhance patient comfort, and possibly reduce hospital stays, all without compromising bleeding control or recovery outcomes.

In conclusion, this study shows that skipping closed-suction drainage during total knee arthroplasty, especially when paired with the right amount of tranexamic acid, doesn’t negatively impact postoperative results like blood loss, hemoglobin levels, range of motion, pain, or complication rates. Sure, there were some slight early perks in reducing swelling with drains, but those didn’t lead to any significant clinical benefits or long-term improvements in function. These results back up the growing belief that, with effective antifibrinolytic therapy available, using drains routinely might not be necessary. This opens the door for a more straightforward postoperative process that keeps patient safety and recovery on track.

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