Knee Osteoarthritis (Knee OA), Postoperative Hematoma, Total Knee Anthroplasty
Conditions
Brief summary
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.
Detailed description
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.
Interventions
PROCEDUREDrain Removal Before CPM
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.
PROCEDUREDrain Removal After CPM
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.
Sponsors
Ankara Etlik City Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
NONE
Intervention model description
Two-arm prospective parallel-group comparison of drain removal timing.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Residual Hematoma Formation | 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
| Measure | Time frame | Description |
|---|---|---|
| Oxford Knee Score | 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. |
| Wound Healing | 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. |
| Lysholm Knee Score | Preoperative; Postoperative Day 28 | Knee function assessed using the Lysholm Knee Score, ranging from 0 to 100, where higher scores indicate better knee function. |
| Pain Assessment | 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. |
| Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) | 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. |
| Range of Motion (ROM) | 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. |
Countries
Turkey (Türkiye)
Outcome results
None listed