gms | German Medical Science

Objectives: A Customized, Individually Made (CIM) TKA implant with a patient customized femoral component, customized tibial component and customized inserts has recently become available. The primary objective of this novel implant is to provide superior clinical outcomes, while reducing the risk of adverse events. Preliminary data obtained with this implant are encouraging. We report on the safety profile and outcomes for patients implanted with the CIM-TKA. Hence, the objective of this multicenter study was to prospectively analyze adverse events and outcomes scores on a larger series of patients implanted with a CIM-TKA.

Methods: At 9 centers a cohort of 303 patients were prospectively recruited and implanted with a CIM-TKA (iTotal CR, ConforMIS Inc., Bedford-MA). Institutional Review Board approval was obtained at all sites and all patients were consented prior to participating in the study. Consistent with the indications for cruciate retaining TKA, patients with compromised cruciate or collateral ligaments or having a varus/valgus deformity >15o were excluded from the study. Post-operative adverse events such as manipulations under anesthesia (MUA), transfusions and revision rates were tracked. In addition, patients were assessed for Range of Motion, the 2011 Knee Society Knee Scoring System^© (KSS), The Knee Injury and Osteoarthritis Outcome Score (KOOS) pre-operatively, at 6-months post-op, and 1 year post-operatively.

Results and Conclusion: Average age of the patient population was 65.4yrs (range: 40-84), while the average BMI was 30 (range: 18.5-41). 53% of the enrolled patients were female. Post-operative analysis of the 303 patients revealed that range of motion significantly improved from an average of 110o preoperatively to 123o at 2 years (p<0.05). Patients demonstrated significant improvements across all 5 domains of the KOOS (p<0.05) and 3 out of 4 domains of the KSS (Objective, Function and Satisfaction) (p<0.05) at two years. There have been 2 complete revisions (1 due to traumatic fracture from patient fall and 1 due to nickel allergy) to OTS TKA to date. 9 (2.97%) patients underwent MUAs and 5 patients (1.65%) received a blood transfusion after surgery.

The 1-year follow up data collected on CIM-TKA compares favorably to adverse events rate, as well as patient outcome scores, when compared to multicenter studies published on off-the-shelf implants. The manipulation rates of the CIM-TKA (2.97%) compare favorably to the published literature for OTS implants (4.6%) [1]. Results from this study also support previous findings2 that patients implanted with the CIM-TKA experience significant improvements in outcome scores from baseline post-surgery.