title: Bicompartmental individualized knee replacement : Use of patient-specific implants and instruments (iDuo™).
abstract: OBJECTIVE
  Bicompartmental knee replacement in patients with combined osteoarthritis (OA) of the medial or lateral and patellofemoral compartment. Patient-specific instruments and implants (ConforMIS iDuo™) with a planning protocol for optimal implant fit.
  
  
  METHODS
  Bicompartmental OA of the knee (Kellgren & Lawrence stage IV) affecting both the medial or lateral and patellofemoral compartment after unsuccessful conservative or joint-preserving surgery.
  
  
  METHODS
  Tricompartmental OA, knee ligament instabilities, knee deformities >15° (varus, valgus, extension deficit). Relative contraindication: body mass index >40; prior unicompartmental knee replacement or osteotomies.
  
  
  METHODS
  Midline or parapatellar medial skin incision, medial arthrotomy; identify mechanical contact zone of the intact femoral condyle (linea terminalis); remove remaining cartilage and all osteophytes that may interfere with the correct placement of the individually designed instruments. Balance knee in extension with patient-specific balancing chips. Resection of proximal tibia with an individual cutting block; confirm axial alignment using an extramedullary alignment guide, balance flexion gap using spacer blocks in 90° flexion. Final femur preparation with resection of the anterior trochlea. After balancing and identification of insert heights, final tibial preparation is performed. Implant is cemented in 45° of knee flexion. Remove excess cement and final irrigation, followed by closure.
  
  
  METHODS
  Sterile wound dressing; compressive bandage. No limitation of active/passive range of motion (ROM). Partial weight bearing 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
  In all, 44 patients with bicompartmental OA of the medial and patellofemoral compartment were treated. Mean age 59 years. Minimum follow-up 12 months. Implant converted to TKA due to tibial loosening (1 patient); patella resurfacing (3 patients). No further revisions or complications. Radiographic analyses demonstrated ideal fit of the implant with less than 2 mm subsidence or overhang. KSS pain scores improved from preoperatively 5.7 to 1.7 postoperatively with level walking, and from 7.3 preoperatively to 2.8 postoperatively with climbing stairs or inclines. The WOMAC score improved from preoperatively 43 to 79 postoperatively.
authors.affiliation: Department of Orthopaedic Surgery, Orthopädische Klinik König-Ludwig-Haus, Julius-Maximilians-University Würzburg, Brettreichstraße 11, 97074, Würzburg, Germany.
authors.forename: A F
authors.initials: AF
authors.lastname: Steinert
authors.affiliation: Sportklinik Stuttgart, Taubenheimstrasse 8, 70372, Stuttgart, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Beckmann
authors.affiliation: Department of Orthopaedic Surgery, Orthopädische Klinik König-Ludwig-Haus, Julius-Maximilians-University Würzburg, Brettreichstraße 11, 97074, Würzburg, Germany.|Regenerative Medicine, Institute of Health and Biomedical Innovation, Queensland University of Technology, 60 Musk Avenue, 4059, Kelvin Grove, Brisbane, Australia.
authors.forename: B M
authors.initials: BM
authors.lastname: Holzapfel
authors.affiliation: Department of Orthopaedic Surgery, Orthopädische Klinik König-Ludwig-Haus, Julius-Maximilians-University Würzburg, Brettreichstraße 11, 97074, Würzburg, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Rudert
authors.affiliation: Department of Orthopaedic Surgery, Orthopädische Klinik König-Ludwig-Haus, Julius-Maximilians-University Würzburg, Brettreichstraße 11, 97074, Würzburg, Germany. j-arnholdt.klh@uni-wuerzburg.de.
authors.forename: J
authors.initials: J
authors.lastname: Arnholdt
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods* / Q000534:rehabilitation; D019317:Evidence-Based Medicine; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000601:surgery*; D057071:Patellofemoral Joint / Q000000981:diagnostic imaging / Q000601:surgery*; D018802:Patient-Centered Care / Q000379:methods; D011474:Prosthesis Design; D017755:Prosthesis Fitting / Q000295:instrumentation / Q000379:methods*; D016896:Treatment Outcome
keywords: Bicompartmental knee arthroplasty; Knee joint; Patellofemoral knee osteoarthritis; Patient-specific implants; Patient-specific instruments