Osteo Arthritis of the Knee
Conditions
Keywords
Robot-Assisted Total Knee Arthroplasty, Minimally Invasive Surgery, Minimal Incision, MISI
Brief summary
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.
Detailed description
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.
Interventions
PROCEDUREMISI Robot-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.
PROCEDUREStandard Robotic-Assisted Total Knee Arthroplasty
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.
Sponsors
Hallym University Kangnam Sacred Heart Hospital
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
SINGLE (Outcomes Assessor)
Masking description
Participants will not be informed of their assigned intervention. The operating surgeon and surgical team cannot be masked because they perform the assigned procedure. Postoperative clinical and scar assessments will be conducted by an independent outcome assessor who was not involved in the surgery and is unaware of the treatment allocation. Because the interventions result in different incision and pin-site patterns, complete maintenance of participant masking cannot be guaranteed.
Intervention model description
Participants will be randomly assigned in a 1:1 ratio to either the MISI technique or the standard technique for robotic-assisted total knee arthroplasty.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Adults aged 18 years or older * Degenerative knee osteoarthritis requiring robotic-assisted total knee arthroplasty * Body mass index below 30 kg/m² * Preoperative knee flexion of 90 degrees or greater * Ability to understand the study information and provide written informed consent
Exclusion criteria
* Skin lesions or conditions that may adversely affect wound healing * Previous intra-articular surgery of the affected knee * Inflammatory arthritis, including rheumatoid arthritis * Severe hepatic or renal disease associated with poor general health * Comorbid conditions that may substantially affect mobility, including Parkinson disease, sequelae of poliomyelitis, or stroke * Inability or unwillingness to complete the required follow-up * Any medical or other condition that, in the investigator's judgment, makes participation inappropriate
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Patient and Observer Scar Assessment Scale Score | 3 months after surgery | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Patient and Observer Scar Assessment Scale Score | 3 and 6 weeks after surgery | 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. |
| Main Surgical Incision Length | During surgery and on postoperative day 1 | 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. |
| Intraoperative Incision Stretching Index | During surgery | 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. |
| Postoperative Gauze Oozing Grade | Postoperative days 1, 2, 4, and 6 | 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. |
| Thigh Pain at Rest on the Numeric Rating Scale | Postoperative days 1, 2, 4, and 6 | 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. |
| Thigh Pain During Active Hip Flexion on the Numeric Rating Scale | Postoperative days 1, 2, 4, and 6 | 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. |
| Tenderness at the Standardized Tracking Pin-Site Location | Postoperative days 1, 2, 4, and 6 | 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. |
| Ability to Perform Straight-Leg Raising | Postoperative days 1, 2, 4, and 6 | 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. |
| Pain During the Resisted Straight-Leg-Raising Test | Postoperative days 1, 2, 4, and 6 | 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. |
| Incidence of Tracking Pin-Site Complications | Postoperative days 1, 2, 4, and 6 and postoperative week 3 | 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. |
| Forgotten Joint Score-12 | 6 and 12 months after surgery | 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. |
| Western Ontario and McMaster Universities Osteoarthritis Index | 6 and 12 months after surgery | 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. |
Countries
South Korea
Contacts
CONTACTHo-Jung Jung, MD, PhD
PRINCIPAL_INVESTIGATORJoong-Il Kim, MD, PhD
Hallym University Kangnam Sacred Heart Hospital
Outcome results
None listed