An interventional study of MISI Robot-Assisted Total Knee Arthroplasty and Standard Robotic-Assisted Total Knee Arthroplasty in Osteo Arthritis of the Knee, sponsored by Hallym University Kangnam Sacred Heart Hospital. Not yet recruiting at 1 site in South Korea. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-08-14.
Sponsored by Hallym University Kangnam Sacred Heart Hospital · Not applicable, Interventional, and Treatment
This randomized controlled trial will compare a minimal-incision and soft-tissue-preserving (MISI) technique with the standard surgical technique in patients undergoing robotic-assisted total knee arthroplasty for knee osteoarthritis. A total of 100 participants will be randomly assigned in a 1:1 ratio to undergo either the MISI technique, which uses a reduced skin incision, limited soft-tissue dissection, and modified tracking pin placement, or the standard technique. The primary outcome is postoperative scar assessment at 3 months. Secondary outcomes include incision length, wound oozing, thigh pain and tenderness, recovery of straight-leg raising, tracking pin-related complications, patellar height, patient-reported scar assessments, and functional outcomes during follow-up.
Robotic-assisted total knee arthroplasty requires surgical exposure and placement of tracking pins. Conventional techniques may involve a relatively long incision, broader soft-tissue dissection, and diaphyseal pin insertion. The MISI technique was developed to reduce surgical invasiveness through a shorter incision, limited soft-tissue dissection, and modified tracking pin placement that avoids diaphyseal pin insertion.
Participants will be randomly assigned to the MISI or standard technique in a 1:1 ratio. Clinical evaluations will be performed during follow-up for up to 12 months. The study will assess whether the MISI technique improves scar-related outcomes and early recovery without increasing procedure-related complications.
Exclusion Criteria:
Participants will undergo robotic-assisted total knee arthroplasty using the minimal incision and minimal soft-tissue injury (MISI) technique. The procedure uses an approximately 10-cm main incision with limited soft-tissue dissection. Two femoral tracking pins are inserted through the main incision, and one tibial tracking pin is inserted through an additional approximately 5-mm incision.
Procedure: MISI Robot-Assisted Total Knee Arthroplasty
Participants will undergo robotic-assisted total knee arthroplasty using the standard surgical technique. Tracking arrays are secured using the conventional pin placement method, with four tracking pins placed in the femoral and tibial regions and an additional femoral incision.
Procedure: Standard Robotic-Assisted Total Knee Arthroplasty
Robot-assisted total knee arthroplasty performed using an approximately 10-cm main incision, limited soft-tissue dissection, two femoral tracking pins inserted through the main incision, and one tibial tracking pin inserted through an additional approximately 5-mm incision.
Robot-assisted total knee arthroplasty performed using the standard incision and soft-tissue exposure, with conventional placement of four tracking pins in the femoral and tibial regions and an additional femoral incision.
Patient and Observer Scar Assessment Scale Score
The combined Patient and Observer Scar Assessment Scale (POSAS) score is calculated by summing the total Patient Scale score and the total Observer Scale score. Each scale consists of six items rated from 1 to 10, resulting in a score of 6 to 60 for each scale and a combined score ranging from 12 to 120. Higher scores indicate poorer scar quality. The Observer Scale will be completed by an independent outcome assessor blinded to treatment allocation.
Time frame: 3 months after surgery
Patient and Observer Scar Assessment Scale Score
The combined Patient and Observer Scar Assessment Scale (POSAS) score is calculated by summing the total Patient Scale score and the total Observer Scale score. Each scale consists of six items rated from 1 to 10, resulting in a score of 6 to 60 for each scale and a combined score ranging from 12 to 120. Higher scores indicate poorer scar quality. The Observer Scale will be completed by an independent outcome assessor blinded to treatment allocation.
Time frame: 3 and 6 weeks after surgery
Main Surgical Incision Length
The length of the main surgical incision will be measured in centimeters. The initial incision length will be measured immediately after the skin incision with the knee in extension, and the final incision length will be measured before wound closure. The incision length will also be evaluated on postoperative day 1. Separate tracking pin-site incisions will not be included.
Time frame: During surgery and on postoperative day 1
Intraoperative Incision Stretching Index
The incision stretching index is calculated as the maximum length of the main incision during knee flexion and maximal surgical retraction divided by the initial incision length measured with the knee in extension. A value of 1 indicates no stretching, and higher values indicate greater intraoperative stretching of the incision and surrounding soft tissue.
Time frame: During surgery
Postoperative Gauze Oozing Grade
Postoperative wound oozing will be assessed according to the amount of blood or exudate visible on the surgical dressing using a prespecified ordinal grading scale. Higher grades indicate more extensive wound oozing.
Time frame: Postoperative days 1, 2, 4, and 6
Thigh Pain at Rest on the Numeric Rating Scale
Participants will rate thigh pain at rest using an 11-point numeric rating scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain.
Time frame: Postoperative days 1, 2, 4, and 6
Thigh Pain During Active Hip Flexion on the Numeric Rating Scale
Participants will rate thigh pain during active hip flexion while maintaining knee extension and without external resistance. Pain will be assessed using an 11-point numeric rating scale ranging from 0 to 10, where 0 indicates no pain and 10 indicates the worst imaginable pain.
Time frame: Postoperative days 1, 2, 4, and 6
Tenderness at the Standardized Tracking Pin-Site Location
Tenderness elicited by palpation at a prespecified standardized anatomical location corresponding to the tracking pin region will be rated using an 11-point numeric rating scale ranging from 0 to 10, where 0 indicates no tenderness and 10 indicates the worst imaginable tenderness.
Time frame: Postoperative days 1, 2, 4, and 6
Ability to Perform Straight-Leg Raising
The participant's ability to independently raise the operated lower extremity while maintaining knee extension will be recorded as a binary outcome: able or unable to perform straight-leg raising. The number and proportion of participants able to perform the test will be compared between groups.
Time frame: Postoperative days 1, 2, 4, and 6
Pain During the Resisted Straight-Leg-Raising Test
Pain during resisted straight-leg raising will be assessed using a 100-mm visual analog scale, where 0 mm indicates no pain and 100 mm indicates the worst imaginable pain.
Time frame: Postoperative days 1, 2, 4, and 6
Incidence of Tracking Pin-Site Complications
Tracking pin sites will be examined for complications, including erythema, swelling, wound drainage, infection, and pin-related fracture. The occurrence of one or more prespecified pin-site complications will be recorded as a binary outcome, and the number and proportion of participants with any complication will be reported.
Time frame: Postoperative days 1, 2, 4, and 6 and postoperative week 3
Forgotten Joint Score-12
The Forgotten Joint Score-12 is a 12-item patient-reported questionnaire assessing awareness of the operated knee during daily activities. Scores are transformed to a scale ranging from 0 to 100, with higher scores indicating less awareness of the artificial joint and a better outcome.
Time frame: 6 and 12 months after surgery
Western Ontario and McMaster Universities Osteoarthritis Index
The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) assesses knee pain, stiffness, and physical function. The 24 items are scored using a 5-point Likert scale, producing a total score ranging from 0 to 96. Higher scores indicate more severe symptoms and poorer physical function.
Time frame: 6 and 12 months after surgery
Plan to share: No
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Hallym University Kangnam Sacred Heart Hospital