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NCT Number: NCT07302724

Drain Removal Before Versus After CPM in Primary Total Knee Arthroplasty

The aim of this prospective randomized controlled study was to determine whether the timing of drain removal in relation to continuous passive motion (CPM) application influences postoperative residual hematoma formation following primary total knee arthroplasty (TKA). Our primary hypothesis was that removing the drain after initiating CPM would result in less residual hematoma, as CPM-induced intra-articular fluid and blood mobilization would be evacuated through the drain before its removal, thereby reducing postoperative fluid accumulation.

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Key information

Conditions

Knee Osteoarthritis (Knee OA) Arthritis Joint Diseases Musculoskeletal Diseases Osteoarthritis Osteoarthritis, Knee Postoperative Hematoma Rheumatic Diseases Total Knee Anthroplasty

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Ankara Etlik City Hospital

Ankara, Turkey (Türkiye)

About this study

This prospective, parallel-group interventional study was conducted at a single tertiary care center between June 2025 and December 2025 following approval by the institutional ethics committee. All patients provided written informed consent prior to participation.

A total of 104 consecutive patients undergoing primary unilateral total knee arthroplasty (TKA) were enrolled during the study period. During follow-up, four patients from each group were lost, leaving 96 patients available for final analysis.

Participants were allocated into two groups using a sequential alternating allocation method (2-1-2-1 sequence). Although not computer-generated, this prospective allocation approach ensured balanced group sizes throughout enrollment. Due to the nature of the intervention, allocation concealment and blinding were not applied.

All surgical procedures were performed by senior arthroplasty surgeons using a standardized medial parapatellar approach under spinal anesthesia. A uniform perioperative protocol was applied to all patients, including antibiotic prophylaxis with intravenous cefazolin and thromboembolism prophylaxis with low-molecular-weight heparin. All procedures were performed under tourniquet control. A single standard intra-articular hemovac drain of identical size and model was placed in all patients prior to wound closure.

Postoperatively, all patients underwent a standardized continuous passive motion (CPM) protocol approximately 24 hours after surgery. CPM was applied for 1 hour with a motion range of 0-90 degrees under supervision of the physiotherapy team.

The only interventional difference between study groups was the timing of drain removal in relation to CPM therapy. In the first group, the hemovac drain was removed immediately before initiation of CPM. In the second group, the drain was removed immediately after completion of the CPM session. All other perioperative care and rehabilitation protocols were identical between groups.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age 18 years or older
  • Undergoing primary unilateral total knee arthroplasty (TKA) for end-stage knee osteoarthritis
  • Able to provide written informed consent
  • Able to comply with scheduled postoperative follow-up assessments

Exclusion criteria

  • Revision total knee arthroplasty
  • Previous infection in the index knee
  • Inflammatory arthropathy
  • Neuromuscular disorders affecting lower extremity function
  • Inability to attend follow-up visits

Treatment and study plan

Drain Removal Before CPM

Procedure

Hemovac drain removal performed approximately 24 hours after primary TKA, immediately before a standardized 1-hour CPM session (0-90°). All other surgical, perioperative, and rehabilitation protocols are identical across study arms.

Drain Removal After CPM

Procedure

A standardized 1-hour CPM session at 0-90° is administered approximately 24 hours after primary TKA. The hemovac drain is removed immediately after completion of the CPM session. All other surgical, perioperative, and rehabilitation protocols are identical across study arms.

Primary outcomes

  1. Residual Hematoma Formation

    Time frame: Preoperative; Postoperative Day 2; Day 14; Day 28

    Residual hematoma formation assessed by knee circumference measurements at the level of the superior pole of the patella. Circumference is measured on both the operated and contralateral knees. The difference from baseline and between-group differences are evaluated.

Secondary outcomes

  1. Wound Healing

    Time frame: Postoperative Day 2; Day 14

    Wound healing assessed using the Surgical Wound Aspect Score (SWAS), a clinical scoring system evaluating wound characteristics such as swelling (minimum = 0 points, maximum = 2 points), erythema (minimum = 0 points, maximum = 2 points), ecchymosis (minimum = 0 points, maximum = 2 points), blood drainage (minimum = 0 points, maximum = 2 points), and blisters (minimum = 0 points, maximum = 2 points). Finally, a score of 0 points (the best) to 10 points (the worst) was obtained by adding the results of these 5 parameters.

  2. Range of Motion (ROM)

    Time frame: Preoperative; Postoperative Day 2; Day 14; Day 28

    Goniometric measurement of knee flexion and extension on the operated limb. Differences from baseline and between groups are evaluated across postoperative follow-up visits.

  3. Pain Assessment

    Time frame: Preoperative; Postoperative Day 14; Day 28

    Pain intensity assessed using the Visual Analog Scale (VAS), ranging from 0 to 10, where 0 represents no pain and 10 represents the worst imaginable pain. Higher scores indicate greater pain severity.

  4. Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC)

    Time frame: Preoperative; Postoperative Day 28

    Functional outcome assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), ranging from 0 to 96, where higher scores indicate worse pain, stiffness, and functional limitation.

  5. Lysholm Knee Score

    Time frame: Preoperative; Postoperative Day 28

    Knee function assessed using the Lysholm Knee Score, ranging from 0 to 100, where higher scores indicate better knee function.

  6. Oxford Knee Score

    Time frame: Preoperative; Postoperative Day 28

    Patient-reported knee function assessed using the Oxford Knee Score, ranging from 0 to 48, where higher scores indicate better knee function.

Sponsors and collaborators

Lead sponsor

Ankara Etlik City Hospital

Other Gov

Registry information

Official study title

Drain Removal Before Versus After Continuous Passive Motion in Primary Total Knee Arthroplasty: Impact on Residual Hematoma in a Prospective Controlled Study

Important dates

Study start
2025
Primary completion
2025
Study completion
2025
First posted
Dec 24, 2025
Registry last updated
Dec 24, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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