Comparing two ways of positioning knee replacement implants and how they affect recovery, movement, and patient satisfaction after knee replacement surgery
| ISRCTN | ISRCTN13254958 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN13254958 |
| Sponsor | General University Hospital of Patras |
| Funder | Investigator initiated and funded |
- Submission date
- 26/04/2026
- Registration date
- 27/06/2026
- Last edited
- 15/06/2026
- Recruitment status
- Recruiting
- Overall study status
- Ongoing
- Condition category
- Musculoskeletal Diseases
Plain English summary of protocol
Background and study aims
Total knee replacement is a common operation used to treat severe knee arthritis. It usually reduces pain and helps people move more easily. However, some people are not fully satisfied after surgery and feel that their new knee does not move as naturally as they expected. Surgeons currently use different methods to position the knee replacement during surgery. This study aims to compare two of these methods to see how they affect pain, movement, daily function, and how satisfied patients feel after surgery. The overall goal is to find out whether one approach leads to better outcomes for patients.
Who can participate?
Adults aged 60–80 years with severe knee osteoarthritis who are scheduled to have a total knee replacement may be able to take part. Participants must not have had previous knee surgery and must be able and willing to attend follow-up visits for up to 2 years after their operation. People with certain medical conditions, such as inflammatory joint disease or major nerve or muscle problems affecting walking, cannot take part.
What does the study involve?
Participants will receive a standard total knee replacement as part of their normal clinical care. The difference between groups is how the surgeon positions the knee implant. One group will have the knee aligned using a traditional method that follows standard measurements, while the other group will have the knee aligned to better match their natural knee shape. After surgery, participants will attend follow-up appointments at 6 months, 12 months, and 24 months. At these visits, they will be asked to complete questionnaires about pain, knee function, quality of life, and satisfaction. X-rays will also be taken to assess knee alignment, and the research team will review medical records for any complications.
What are the possible benefits and risks of participating?
Participants may benefit from close follow-up after surgery and from contributing to research that could improve knee replacement outcomes in the future. However, taking part may not directly improve their own surgical result. The risks are the same as those linked to routine knee replacement surgery and standard follow-up care, including exposure to X-rays and the possibility of surgical complications. No additional major risks are expected from participating in the study.
Where is the study run from?
The study is run from the General University Hospital of Patras in Greece.
When is the study starting and how long is it expected to run for?
The study began recruiting participants in January 2025. Recruitment is expected to finish in January 2028, with follow-up continuing until January 2029.
Who is funding the study?
The study is investigator initiated and funded.
Who is the main contact?
Mr Michail Kroustalakis, mikekroustalakis@gmail.com
Contact information
Principal investigator, Public, Scientific
Tellou Agra 26
PATRAS
26442
Greece
 ORCID ID |
0009-0004-6937-5764 |
|---|---|
| Phone | +30 6939400309 |
| mikekroustalakis@gmail.com |
Study information
| Primary study design | Observational |
|---|---|
| Observational study design | Case-control study |
| Participant information sheet | 49425 PIS (Greek).pdf |
| Scientific title | A case-control study of clinical outcomes, functional performance, and patient satisfaction in kinematically aligned vs. mechanically aligned total knee arthroplasty using medial pivot implants |
| Study objectives | 1. Comparison of pre-operative and postoperative radiological image using the Coronal Plane Alignment of the Knee (CPAK) classification. 2. Patient reported outcomes that include pain, satisfaction rate and quality of life. 3. Comparison of Functional Performance: Range of Motion (ROM), results between the two groups. 4. Postoperative complications: implant wear, implant malalignment, revision rates. |
| Ethics approval(s) |
Approved 08/07/2025, Research and Ethics Committee of the University General Hospital of Patras (General University Hospital of Patras, Rio, Patras, 26504, Greece; +30 261 360 3000-3554; kefiap@pgnp.gr), ref: 283/8-7-2025 |
| Health condition(s) or problem(s) studied | Outcomes of kinematic alignment versus mechanical alignment technique in patients undergoing Total Knee Arthroplasty, using medial pivot implants |
| Methodology | The current study is a case–control study will compare outcomes between kinematically aligned (KA) and mechanically aligned (MA) total knee arthroplasty using medial pivot implants. Patients with end-stage knee osteoarthritis meeting eligibility criteria will be recruited and randomized into two groups. The surgical technique will be roughly the same differing only in the alignment of the limb. Baseline clinical and radiological data will be collected preoperatively, with follow-up assessments at 6, 12, and 24 months. Primary outcomes include patient-reported measures of pain, function, and satisfaction using scoring systems. Secondary outcomes include radiographic alignment, range of motion, and complication rates. Patients and outcome assessors will be blinded to group allocation. Statistical analysis will compare outcomes between groups, with significance set at p <0.05. Ethical approval and informed consent will be obtained prior to study initiation. |
| Intervention type | Procedure/Surgery |
| Primary outcome measure(s) |
|
| Key secondary outcome measure(s) |
|
| Completion date | 01/01/2029 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 60 Years |
| Upper age limit | 80 Years |
| Sex | All |
| Target sample size at registration | 50 |
| Key inclusion criteria | 1. Adults between 60-80 years old 2. Patients with end stage (K-L 3,4) primary knee osteoarthritis 3. Indicated for TKA 4. Eager and able to comply with the 2-year study’s follow-up |
| Key exclusion criteria | 1. Severe valgus or varus deformity (>15°) 2. Previous knee surgery 3. Inflammatory joint disease affecting the knee joint 4. Neuromuscular disorder affecting gait 5. BMI > 40 kg/m² |
| Date of first enrolment | 01/01/2025 |
| Date of final enrolment | 01/01/2028 |
Locations
Countries of recruitment
- Greece
Study participating centres
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|
Study outputs
| Output type | Details | Date created | Date added | Peer reviewed? | Patient-facing? |
|---|---|---|---|---|---|
| Other files | Sample size calculations | 27/04/2026 | No | No | |
| Participant information sheet | In Greek | 27/04/2026 | No | Yes | |
| Protocol file | 27/04/2026 | No | No |
Additional files
- 49425 Protocol.pdf
- Protocol file
- 49425 PIS (Greek).pdf
- In Greek
- 49425 Sample size calculations.pdf
- Sample size calculations
Editorial Notes
27/04/2026: Trial's existence confirmed by Research and Ethics Committee of the University General Hospital of Patras.
