Patient-specific cruciate-retaining total knee replacement with individualized implants and instruments (iTotal™ CR G2)

Objective Treatment of tricompartimental osteoarthritis (OA) using customized instruments and implants for cruciate-retaining total knee arthroplasty. Use of patient-specific instruments and implants (ConforMIS iTotal(TM) CR G2) together with a 3D-planning protocol (iView (R)). Retropatellar resurfacing is optional. Indications Symptomatic tricompartmental OA of the knee (Kellgren-Lawrence stage IV) with preserved posterior cruciate ligament (PCL) after unsuccessful conservative or joint-preserving surgical treatment. Contraindications Knee ligament instabilities of the posterior cruciate or collateral ligaments. Infection. Relative contraindication: knee deformities >15 degrees (varus, valgus, flexion); prior partial knee replacement. Surgical technique Midline or parapatellar medial skin incision, medial arthrotomy; distal femoral resection with patient-specific cutting block; tibial resection using either a cutting jig for the anatomic slope or a fixed 5 degrees slope. Balancing the knee in extension and flexion gap using patient-specific spacer. The final tibial preparation achieved with gap-balanced placement of the femoral cutting jigs. Kinematic testing using anatomic trial components. Final implant components are cemented in extension. Wound layers are sutured. Drainage is optional. Postoperative management Sterile wound dressing; compressive bandage. No limitation of the active and passive range of motion. Optional partial weight bearing during the first 2 weeks, then transition to full weight bearing. Follow-up directly after surgery, at 12 and 52 weeks, then every 1-2 years. Results Overall 60 patients with tricompartmental knee OA and preserved PCL were treated. Mean age was 66 (range 45-76) years. Minimum follow-up was 12 months. There was 1 septic revision after a low-grade infection, 1 reoperation to replace the patellar due to patellar osteoarthritis and 3 manipulations under anesthesia (MUAs) to increase range of motion. Radiographic analyses demonstrated an ideal implant fit with less than 2 mm subsidence or overhang. The WOMAC score improved from 154.8 points preoperatively to 83.5 points at 1 year and 59.3 points at 2 years postoperatively. The EuroQol-5D Score also improved from 11.1 points preoperatively to 7.7 points at 1 year postoperatively.

Automated summary

This study treated 60 patients with tricompartimental knee osteoarthritis and preserved PCL using customized instruments and implants, resulting in significant symptomatic improvement postoperatively with low rate of adverse events.