gms | German Medical Science

Objectives: Over the past decade, the number of uni-compartmental knee arthroplasties (UKA) performed has increased by 30%, as numerous studies have demonstrated shorter hospital stays, decreased perioperative morbidity, faster functional recovery, increased range of motion (ROM), and improved knee kinematics versus total knee arthroplasty (TKA). More recently, a customized, individually made (CIM) UKA has been introduced in the market, which reproduces the patient's J-curve, with the goals of improving patient satisfaction and functional outcomes. However, there are no known studies that report the clinical and functional outcomes of this device. Hence, the purpose of this study was to assess clinical and patient-reported outcomes utilizing CIM unicondylar knee replacement (UKR) prostheses.

Methods: A prospectively recruited cohort of 118 patients were implanted with 120 CIM-UKR (110 were medial/10 lateral) at 8 centers. Patients who were diagnosed with unicompartmental osteoarthritis of the medial or lateral compartment and consented to take part in the study were included. Patients with a BMI>35, compromised cruciate or collateral ligaments or had a varus/valgus deformity >15o were excluded from the study. Patients were assessed for the Knee Society Knee and Function Scores, WOMAC & ROM pre-operatively, at 6-months post-op, 1 year post-op and 2 years post-operatively. Patients were also asked about their satisfaction level and if the movement of their implanted knee felt natural.

Results: Range-of-motion was improved to an average of 11o from 120o pre-operatively to 131o at 2 years post-op (117o at 6 wks, 129o at 6 months and 129o at 1 year). Patients demonstrated marked improvements from baseline scores across all measured domains. A total of 96 patients have reached their 2-year follow up visit to date. Average KSS Knee Scores at 2-years are 94, KSS Function 91, scaled WOMAC 90, and VAS Pain 1.3. Additionally, 99% of patients said they were satisfied, with 89% reporting they were very or extremely satisfied with their UKR and 89% stated that the movement of their knee felt natural. To date 2 patients have undergone revision for tibial loosening yielding a mechanical revision rate of 1.67% at the 2 year post-operative interval.

Discussion: There are a multitude of studies of off-the-shelf mobile and fixed-bearing UKR. The 2-year follow up data collected on CIM UKR compares favorably to both published scores as well as revision rates for off-the-shelf implants. Importantly, a very high percentage of patients reportedly were extremely satisfied with the CIM UKR procedure. Additionally, 89% of patients reported that they had a natural feeling in their CIM UKR.