Prospective Comparative Study of Clinical Outcomes and Complications in Medial Knee Prostheses: Fixed Bearing Versus Mobile Bearing Design (FiMo_UKP)

This prospective study aims to systematically compare the clinical and radiological outcomes and complications of mobile versus fixed unicompartimental knee prostheses.

Study Overview

• Status: Recruiting
• Conditions: Medial Gonarthrosis

Detailed Description

In knee surgery, two dominant designs exist for the medial unicompartmental knee prosthesis (UKP): the fixed bearing (FB) and mobile bearing (MB) designs. The FB design is technically simpler to implant but has shown higher rates of early polyethylene wear in some studies. MB implants theoretically offer advantages in joint kinematics and load distribution but carry a risk of insert dislocation and periprosthetic fractures. An additional advantage of MB implants is the possibility of cementless implantation, potentially avoiding cement-related complications and reducing operative time.

• Study Type: Observational
• Enrollment (Estimated): 200

Contacts and Locations

• Study Contact: Name: Lenka Stroobant; Phone Number: +32496867115; Email: lenka.stroobant@ugent.be

Study Locations

• Belgium
  • Oost-Vlaanderen
    • Ieper, Oost-Vlaanderen, Belgium, 8900
      • Recruiting
      • Orthopedic department
      • Contact: Francois Hardeman, MD; Phone Number: 057 35 73 70; Email: francois.hardeman@yperman.net

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Probability Sample

Study Population

Patients eligible for a unicompartmental medial knee prosthesis based on the eligibility criteria.

Description

Inclusion Criteria:

• Age between 50 and 80 years
• Indication for medial UKP
• Intact anterior cruciate ligament
• Good bone quality based on imaging
• ASA score ≤ 3

Exclusion Criteria:

• Inflammatory joint diseases
• Collateral ligament instability
• Simultaneous bilateral procedure
• BMI > 35
• History of fracture or osteotomy in the knee joint
• Neuromuscular diseases
• Oncological indications

Study Plan

How is the study designed?

Number of groups / cohorts

2

Cohorts and Interventions

Group / Cohort
Mobile UKP; Mobile unicompartmental knee prosthesis
Fixed UKP; Fixed unicompartmental knee prosthesis

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
OKS	Oxford Knee Score	Preoperatively, 6 weeks, 4 months, 12 months, and 24 months postoperatively.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
AMI	Arthrogenic Muscle Inhibition - DOI: 10.1002/ksa.12804 for grading	Evaluate AMI (Arthrogenic Muscle Inhibition) preoperative, at 6 weeks and 4 months postoperative.
Surgery time	Operative time	Peroperatively
Complications	Postoperative complications	Within 2 years postoperatively
Revision or reoperation	Revision or reoperation	Within 2 years postoperatively
c-FCA	Coronal Femoral Component Alignment - Varus/valgus alignment for the femoral component is measured on the AP radiograph in relation to the anatomical axis of the tibia. 0° degrees is considered neutral.	6 weeks and 4 months postoperatively
EQ-5D-5L	The 5-level EQ-5D version.	Preoperatively, 6 weeks, 4 months, 12 months, and 24 months postoperatively.
NRS	Numeric Rating Scale	Preoperatively, one week, 6 weeks, 4 months, 12 months, and 24 months postoperatively.]
KOOS-PS	Knee Injury and Osteoarthritis Outcome Score-Physical function Short form	Preoperatively, 6 weeks, 4 months, 12 months, and 24 months postoperatively.
c-TCA	Coronal Tibial Component Alignment - Varus/valgus alignment for the tibial component is measured on the AP radiograph in relation to the anatomical axis of the tibia. 0° is considered neutral.	6 weeks and 4 months postoperatively
s-FCA	Sagittal Femoral Component Alignment - Flexion/extension is measured on a lateral radiograph, relative to the posterior tibial cortex. A posteroinferior slope of 7° is considered neutral.	6 weeks and 4 months postoperatively
s-FCA	Sagittal Femoral Component Alignment - Flexion/extension is measured on a lateral radiograph, relative to the posterior femoral cortex. 0° is considered neutral.	6 weeks and 4 months postoperatively
RLL	Radiolucencies - Radiolucencies after UKR are divided into two types: physiological and pathological. The former are < 2 mm thick, well defined, and accompanied by a parallel radiodense line, whereas the latter are > 2 mm thick, ill defined, and lacking accompanying radiodense lines. The pattern observed should be recorded as well as their location, which is divided into six zones on the AP view of the tibial component and six zones on the lateral view of the femoral component. Evaluation based on the zones of the Knee Society.	6 weeks and 4 months postoperatively

Collaborators and Investigators

• Sponsor: Jan Yperman Hospital

Study record dates

Study Major Dates

• Study Start (Actual): December 8, 2025
• Primary Completion (Estimated): December 31, 2029
• Study Completion (Estimated): December 31, 2029

Study Registration Dates

• First Submitted: June 11, 2026
• First Submitted That Met QC Criteria: June 25, 2026
• First Posted (Actual): July 1, 2026

Study Record Updates

• Last Update Posted (Actual): July 1, 2026
• Last Update Submitted That Met QC Criteria: June 25, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: FiMO JYZ2025-10

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No