Total Knee ArthroplastyDOLOTHROKNCT07869615
Comparison of DOACs and LMWH for Thromboprophylaxis After Total Knee Arthroplasty
A study testing Apixaban, Rivaroxaban and Enoxaparin (LMWH) in people with Total Knee Arthroplasty and Venous Thromboembolism, run by Military Hospital of Tunis at 1 site in Tunisia.
Trial summary
Yes. For these two fields, I would enter the following in English, based on your study protocol. 1. Brief Summary Copy and paste: This study aims to compare three thromboprophylaxis regimens in adults undergoing primary total knee arthroplasty: rivaroxaban 10 mg once daily, apixaban 2.5 mg twice daily, and… Read more about this study
- Who is it for?
- Ages 18 to 80 years
- Conditions the study is for
- Total Knee Arthroplasty, Venous Thromboembolism
- What is being tested?
- Apixaban, Rivaroxaban and Enoxaparin (LMWH)
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 138 participants
- Where
- 1 siteTunisia
- Study dates
- 15 Sep 2026to 15 Apr 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 80 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Adults aged 18 years or older undergoing elective primary unilateral total knee arthroplasty.
- Able to provide informed consent.
Who cannot join
- Allergy or contraindication to the study medications.
- Requirement for long-term therapeutic anticoagulation.
- Requirement for antiplatelet therapy.
- Pregnancy or lactation.
- Active cancer or cancer treatment.
- Documented previous venous thromboembolism in the target limb.
Show all 12Show fewer
- Hypercoagulable state.
- BMI >40 kg/m².
- Severe inflammatory disease.
- Age >80 years.
- Inability to comply with follow-up.
- Incomplete data.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Tunisia1 site, 1 recruiting
- Recruiting
Principal Military Hospital of Instruction of Tunis
Tunis, Tunis Governorate
Haythem Professor H. Elaskri, 54015050, haythem.elaskri@fmt.utm.tn
About this study
Official title: Direct Oral Anticoagulants (DOACs) Once Daily (OD) Versus Direct Oral Anticoagulants (DOACs) Twice Daily (TD) Versus Low-Molecular-Weight Heparin (LMWH) for Thromboprophylaxis After Primary Total Knee Arthroplasty: A Duplex Ultrasound Assessment
Yes. For these two fields, I would enter the following in English, based on your study protocol.
- Brief Summary
Read more
Copy and paste:
This study aims to compare three thromboprophylaxis regimens in adults undergoing primary total knee arthroplasty: rivaroxaban 10 mg once daily, apixaban 2.5 mg twice daily, and low-molecular-weight heparin (LMWH) once daily. The study will assess venous blood flow in the lower limbs using Doppler ultrasound and determine whether blood flow differs between the three treatment groups. Participants will be randomly assigned to one of the three treatment groups and followed for 28 days after surgery. Doppler ultrasound examinations will be performed at baseline and on Days 7, 15, 21, and 28. Additional assessments will include rehabilitation progress, postoperative bleeding, suspected venous thromboembolism, cardiovascular complications, and other postoperative complications. The study is being conducted at the Department of Anesthesiology, Principal Military Hospital of Instruction of Tunis.
Read the detailed description
Total knee arthroplasty is associated with a substantial risk of venous thromboembolism, and pharmacological thromboprophylaxis is routinely used after surgery. This study aims to compare three thromboprophylaxis strategies and their effects on postoperative venous hemodynamics following primary total knee arthroplasty.
Eligible adults undergoing elective primary unilateral total knee arthroplasty will be enrolled after providing written informed consent. Participants will be randomly assigned to one of three treatment groups: apixaban 2.5 mg twice daily, rivaroxaban 10 mg once daily, or weight-adjusted enoxaparin 40-60 mg once daily. According to the study protocol, patients receive an initial LMWH prophylactic treatment 6 hours after surgery and subsequently receive the randomized thromboprophylaxis regimen 24 hours after surgery. Treatment is planned for 14 days.
The primary objective is to compare peak systolic velocity (PSV) in major lower-limb veins between the three thromboprophylaxis groups using duplex Doppler ultrasound during the 28-day postoperative period. Additional Doppler parameters will include time-averaged mean velocity, vessel diameter, venous flow volume, respiratory phasicity, distal augmentation, and visible intraluminal sludging.
Secondary assessments will include postoperative rehabilitation, level of immobilization, articular stiffness, range of motion, static and dynamic pain, postoperative bleeding, anticoagulation-related adverse effects or overdose, suspected venous thromboembolism, return to the operating room, infections, and other postoperative complications.
Doppler assessments will be performed at baseline and on Days 7, 15, 21, and 28. The Doppler examiner will be blinded to the assigned anticoagulation regimen. Measurements will be performed using spectral Doppler ultrasound at the common femoral and popliteal veins.
The study plans to recruit at least 138 participants, with a minimum of 46 participants in each treatment group. The sample size was calculated to detect a 15% difference in the mean peak systolic velocity of the common femoral vein, with a two-sided alpha level of 0.05 and 80% statistical power.
- Conditions
- Total Knee Arthroplasty, Venous Thromboembolism
- Being tested
- Apixaban, Rivaroxaban, Enoxaparin (LMWH)
- Keywords
- Total Knee Arthroplasty, Thromboprophylaxis, Venous Blood Flow, Doppler Ultrasound, Rivaroxaban, Apixaban, Low-Molecular-Weight Heparin, Venous Thromboembolism
- Medical subject headings
- Venous Thromboembolism
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
ApixabanDrug
Apixaban 2.5 mg twice daily, starting 24 hours after surgery, for 14 days. Participants receive initial LMWH prophylaxis 6 hours after surgery before starting the assigned regimen.
RivaroxabanDrug
Rivaroxaban 10 mg once daily, starting 24 hours after surgery, for 14 days. Participants receive initial LMWH prophylaxis 6 hours after surgery before starting the assigned regimen.
Enoxaparin (LMWH)Drug
Enoxaparin 40-60 mg once daily, weight-adjusted, starting 6 hours after surgery, for 14 days.
| Study group | Role | What they receive |
|---|---|---|
| Apixaban | Experimental | Participants receive apixaban 2.5 mg twice daily for 14 days. Receives: Drug: Apixaban |
| Rivaroxaban | Experimental | Participants receive rivaroxaban 10 mg once daily for 14 days. Receives: Drug: Rivaroxaban |
| LMWH | Active comparator | Participants receive enoxaparin 40-60 mg once daily, weight-adjusted, for 14 days. Receives: Drug: Enoxaparin (LMWH) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Mean Peak Systolic Velocity of the Common Femoral Vein at Postoperative Days 0, 7, 15, 21, and 28
Peak systolic velocity (PSV) of the common femoral vein will be measured using duplex Doppler ultrasound at baseline (postoperative day 0) and on postoperative days 7, 15, 21, and 28. Results will be expressed in centimeters per second (cm/s) and summarized as mean and standard deviation at each time point for the three thromboprophylaxis groups: apixaban 2.5 mg twice daily, rivaroxaban 10 mg once daily, and enoxaparin once daily. The mean PSV will be compared between groups.
Measured: Postoperative day 0 through day 28.
Secondary outcomes (8)
Mean Time-Averaged Mean Velocity of the Common Femoral and Popliteal Veins
Time-averaged mean blood flow velocity will be measured separately in the common femoral and popliteal veins by duplex Doppler ultrasound at postoperative days 0, 7, 15, 21, and 28. Results will be expressed in centimeters per second (cm/s) and summarized as mean and standard deviation for each vein, treatment group, and time point.
Measured: Within 28 days after surgery
Mean Diameter of the Common Femoral and Popliteal Veins
The diameter of the common femoral vein and popliteal vein will be measured separately by duplex Doppler ultrasound at postoperative days 0, 7, 15, 21, and 28. Results will be expressed in millimeters (mm) and summarized as mean and standard deviation for each vein, treatment group, and time point.
Measured: Within 28 days after surgery
Mean Venous Blood Flow Volume in the Common Femoral and Popliteal Veins
Venous blood flow volume will be measured separately in the common femoral and popliteal veins by duplex Doppler ultrasound at postoperative days 0, 7, 15, 21, and 28. Results will be expressed in [confirmed unit] and summarized as mean and standard deviation for each vein, treatment group, and time point.
Measured: Within 28 days after surgery
Number of Participants with Normal Respiratory Phasicity in the Common Femoral and Popliteal Veins
Respiratory phasicity will be assessed separately in the common femoral and popliteal veins at postoperative days 0, 7, 15, 21, and 28. Findings will be classified as normal or reduced/blunted. The number and percentage of participants with normal respiratory phasicity will be reported for each vein, treatment group, and time point.
Measured: Within 28 days after surgery
Number of Participants with Preserved Distal Venous Flow Augmentation
Distal venous flow augmentation will be assessed separately in the common femoral and popliteal veins at postoperative days 0, 7, 15, 21, and 28 and classified as present or absent. The number and percentage of participants with augmentation present will be reported for each vein, treatment group, and time point.
Measured: Within 28 days after surgery
Number of Participants with Visible Intraluminal Venous Sludging
Visible intraluminal venous sludging will be assessed separately in the common femoral and popliteal veins by duplex Doppler ultrasound. Findings will be classified as present or absent. The number and percentage of participants with visible sludging will be reported for each vein, treatment group, and assessment time point.
Measured: Days 7, 15, 21, and 28
Number of Participants with Postoperative Complications
The number and percentage of participants experiencing clinically relevant postoperative bleeding, anticoagulation-related adverse events or overdose, suspected venous thromboembolism, return to the operating room, or postoperative infection will be reported during the 28-day follow-up. Each complication will be reported separately.
Measured: During the 28-day follow-up
Number of Participants with Postoperative Cardiovascular Complications
The number and percentage of participants experiencing cardiovascular complications during the 28-day postoperative follow-up will be reported. The specific cardiovascular events assessed will be defined according to the study protocol.
Measured: During the 28-day follow-up
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Oct 2026
- Study start15 Sep 2026
- Primary completion15 Apr 2027 (estimated)
- Study completion15 Apr 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Total Knee ArthroplastyStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Participants will be randomly assigned to one of three parallel thromboprophylaxis groups following primary total knee arthroplasty: rivaroxaban 10 mg once daily, apixaban 2.5 mg twice daily, or LMWH once daily. Participants will be followed for 28 days, with Doppler ultrasound assessments performed at baseline and on Days 7, 15, 21, and 28.
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 138 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Military Hospital of Tunis
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07869615
- Sponsor's protocol ID
- DOLOTHROK-2026
- Acronym
- DOLOTHROK
- Status last verified
- Oct 2026
- First submitted
- 4 Oct 2026
- Last updated
- 16 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Individual participant-level data will not be shared with other researchers because the study protocol does not include a plan for external IPD sharing. Participant data will be anonymized and securely stored for the purposes of the study.
Study at a glance
From the registry record, last updated by the sponsor on 16 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Direct Oral Anticoagulants (DOACs) Once Daily (OD) Versus Direct Oral Anticoagulants (DOACs) Twice Daily (TD) Versus Low-Molecular-Weight Heparin (LMWH) for Thromboprophylaxis After Primary Total Knee Arthroplasty: A Duplex Ultrasound Assessment
- ClinicalTrials.gov ID
- NCT07869615
- Acronym / sponsor ID
- DOLOTHROK / DOLOTHROK-2026
- Conditions
- Total Knee Arthroplasty, Venous Thromboembolism
- Keywords
- Total Knee Arthroplasty, Thromboprophylaxis, Venous Blood Flow, Doppler Ultrasound, Rivaroxaban, Apixaban, Low-Molecular-Weight Heparin, Venous Thromboembolism
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 138 participants (estimated)
- Lead sponsor
- Military Hospital of TunisUniversity, hospital or other
- Study start
- 15 Sep 2026 (actual)
- Primary completion
- 15 Apr 2027 (estimated)
- Study completion
- 15 Apr 2027 (estimated)
- First posted
- 9 Oct 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Yes. For these two fields, I would enter the following in English, based on your study protocol.
- Brief Summary
Copy and paste:
This study aims to compare three thromboprophylaxis regimens in adults undergoing primary total knee arthroplasty: rivaroxaban 10 mg once daily, apixaban 2.5 mg twice daily, and low-molecular-weight heparin (LMWH) once daily. The study will assess venous blood flow in the lower limbs using Doppler ultrasound and determine whether blood flow differs between the three treatment groups. Participants will be randomly assigned to one of the three treatment groups and followed for 28 days after surgery. Doppler ultrasound examinations will be performed at baseline and on Days 7, 15, 21, and 28. Additional assessments will include rehabilitation progress, postoperative bleeding, suspected venous thromboembolism, cardiovascular complications, and other postoperative complications. The study is being conducted at the Department of Anesthesiology, Principal Military Hospital of Instruction of Tunis.
Detailed description
Total knee arthroplasty is associated with a substantial risk of venous thromboembolism, and pharmacological thromboprophylaxis is routinely used after surgery. This study aims to compare three thromboprophylaxis strategies and their effects on postoperative venous hemodynamics following primary total knee arthroplasty.
Eligible adults undergoing elective primary unilateral total knee arthroplasty will be enrolled after providing written informed consent. Participants will be randomly assigned to one of three treatment groups: apixaban 2.5 mg twice daily, rivaroxaban 10 mg once daily, or weight-adjusted enoxaparin 40-60 mg once daily. According to the study protocol, patients receive an initial LMWH prophylactic treatment 6 hours after surgery and subsequently receive the randomized thromboprophylaxis regimen 24 hours after surgery. Treatment is planned for 14 days.
The primary objective is to compare peak systolic velocity (PSV) in major lower-limb veins between the three thromboprophylaxis groups using duplex Doppler ultrasound during the 28-day postoperative period. Additional Doppler parameters will include time-averaged mean velocity, vessel diameter, venous flow volume, respiratory phasicity, distal augmentation, and visible intraluminal sludging.
Secondary assessments will include postoperative rehabilitation, level of immobilization, articular stiffness, range of motion, static and dynamic pain, postoperative bleeding, anticoagulation-related adverse effects or overdose, suspected venous thromboembolism, return to the operating room, infections, and other postoperative complications.
Doppler assessments will be performed at baseline and on Days 7, 15, 21, and 28. The Doppler examiner will be blinded to the assigned anticoagulation regimen. Measurements will be performed using spectral Doppler ultrasound at the common femoral and popliteal veins.
The study plans to recruit at least 138 participants, with a minimum of 46 participants in each treatment group. The sample size was calculated to detect a 15% difference in the mean peak systolic velocity of the common femoral vein, with a two-sided alpha level of 0.05 and 80% statistical power.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 3
- Model description
- Participants will be randomly assigned to one of three parallel thromboprophylaxis groups following primary total knee arthroplasty: rivaroxaban 10 mg once daily, apixaban 2.5 mg twice daily, or LMWH once daily. Participants will be followed for 28 days, with Doppler ultrasound assessments performed at baseline and on Days 7, 15, 21, and 28.
| Arm | Type | Receives |
|---|---|---|
| Apixaban | Experimental | Drug: ApixabanParticipants receive apixaban 2.5 mg twice daily for 14 days. |
| Rivaroxaban | Experimental | Drug: RivaroxabanParticipants receive rivaroxaban 10 mg once daily for 14 days. |
| LMWH | Active comparator | Drug: Enoxaparin (LMWH)Participants receive enoxaparin 40-60 mg once daily, weight-adjusted, for 14 days. |
Who may qualify
- Ages
- 18 to 80 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (2 listed)
- Adults aged 18 years or older undergoing elective primary unilateral total knee arthroplasty.
- Able to provide informed consent.
Key exclusion criteria (12 listed)
- Allergy or contraindication to the study medications.
- Requirement for long-term therapeutic anticoagulation.
- Requirement for antiplatelet therapy.
- Pregnancy or lactation.
- Active cancer or cancer treatment.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| ApixabanApixaban 2.5 mg twice daily, starting 24 hours after surgery, for 14 days. Participants receive initial LMWH prophylaxis 6 hours after surgery before starting the assigned regimen. | Drug | Apixaban |
| RivaroxabanRivaroxaban 10 mg once daily, starting 24 hours after surgery, for 14 days. Participants receive initial LMWH prophylaxis 6 hours after surgery before starting the assigned regimen. | Drug | Rivaroxaban |
| Enoxaparin (LMWH)Enoxaparin 40-60 mg once daily, weight-adjusted, starting 6 hours after surgery, for 14 days. | Drug | LMWH |
Primary outcome
Mean Peak Systolic Velocity of the Common Femoral Vein at Postoperative Days 0, 7, 15, 21, and 28
Time frame: Postoperative day 0 through day 28.
Peak systolic velocity (PSV) of the common femoral vein will be measured using duplex Doppler ultrasound at baseline (postoperative day 0) and on postoperative days 7, 15, 21, and 28. Results will be expressed in centimeters per second (cm/s) and summarized as mean and standard deviation at each time point for the three thromboprophylaxis groups: apixaban 2.5 mg twice daily, rivaroxaban 10 mg once daily, and enoxaparin once daily. The mean PSV will be compared between groups.
8 secondary outcomes
Mean Time-Averaged Mean Velocity of the Common Femoral and Popliteal Veins
Time frame: Within 28 days after surgery
Mean Diameter of the Common Femoral and Popliteal Veins
Time frame: Within 28 days after surgery
Mean Venous Blood Flow Volume in the Common Femoral and Popliteal Veins
Time frame: Within 28 days after surgery
Number of Participants with Normal Respiratory Phasicity in the Common Femoral and Popliteal Veins
Time frame: Within 28 days after surgery
Number of Participants with Preserved Distal Venous Flow Augmentation
Time frame: Within 28 days after surgery
Number of Participants with Visible Intraluminal Venous Sludging
Time frame: Days 7, 15, 21, and 28
Number of Participants with Postoperative Complications
Time frame: During the 28-day follow-up
Number of Participants with Postoperative Cardiovascular Complications
Time frame: During the 28-day follow-up
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 16 Oct 2026.
- Individual participant dataSharing planned: No. Individual participant-level data will not be shared with other researchers because the study protocol does not include a plan for external IPD sharing. Participant data will be anonymized and securely stored for the purposes of the study.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Apixaban, Rivaroxaban and Enoxaparin (LMWH) in people with Total Knee Arthroplasty and Venous Thromboembolism, run by Military Hospital of Tunis at 1 site in Tunisia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 16 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Tunisia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Haythem Elaskri (54015050, haythem.elaskri@fmt.utm.tn), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Mean Peak Systolic Velocity of the Common Femoral Vein at Postoperative Days 0, 7, 15, 21, and 28 (time frame: Postoperative day 0 through day 28.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 16 Oct 2026.