title: Imaging features of iBalance, a new high tibial osteotomy: what the radiologist needs to know.
abstract: OBJECTIVE
  To describe the post-surgical imaging appearance and complications of high tibial osteotomy in patients with the iBalance implant system (iHTO; Arthrex, Naples, FL, USA).
  
  
  METHODS
  Retrospective, institutional review board-approved, Health Insurance Portability and Accountability Act-compliant review of imaging after 24 iBalance procedures was performed with attention to: correction of varus malalignment, healing at the osteotomy site, resorption of the osteoinductive compound, and complications.
  
  
  RESULTS
  Immediate correction of the varus deformity was present in all cases. Lobular radiolucency was present in all cases, more pronounced on the lateral knee radiograph, simulating infection or erosive disease. Four radiographic signs of healing were observed: blurring at the opposing osteotomy bony margins and at the osteoinductive compound and the adjacent bone interface, callus formation, and resorption of the osteoinductive compound. Complications were present in 33 % of cases, including fracture through the lateral tibial cortex (21 %), genu varum recurrence (8 %), painful exuberant bone formation (4 %), persistent pain, requiring total knee arthroplasty (4 %), and non-union (after >6 months' follow-up), with suspected infection (4 %).
  
  
  CONCLUSIONS
  Radiologists should be aware of the normal radiographic appearance following iBalance high tibial osteotomy, which may be confused with infection. Radiologists should also be aware of potential post-operative complications and compare all post-operative radiographs with the immediate post-operative examination to detect collapse of the osteotomy site and recurrence of varus angulation.
authors: Department of Radiology, New York University Langone Medical Center, New York, NY, USA. Erin.Fitzgerald@nyumc.org.
authors: Erin FitzGerald
authors: EF
authors: Alaia
authors: Department of Radiology, New York University Langone Medical Center, New York, NY, USA.
authors: Christopher J
authors: CJ
authors: Burke
authors: Department of Orthopedic Surgery, Hospital for Joint Diseases/New York University Langone Medical Center, New York, NY, USA.
authors: Michael J
authors: MJ
authors: Alaia
authors: Department of Orthopedic Surgery, Hospital for Joint Diseases/New York University Langone Medical Center, New York, NY, USA.
authors: Eric J
authors: EJ
authors: Strauss
authors: Department of Radiology, New York University Langone Medical Center, New York, NY, USA.
authors: Gina A
authors: GA
authors: Ciavarra
authors: Centro de Diagnóstico Dr. Enrique Rossi, Buenos Aires, Argentina.
authors: Ignacio
authors: I
authors: Rossi
authors: Department of Radiology, New York University Langone Medical Center, New York, NY, USA.
authors: Zehava Sadka
authors: ZS
authors: Rosenberg
mesh_terms: D000328:Adult; D017760:Bone Malalignment / Q000000981:diagnostic imaging* / Q000601:surgery*; D000069343:Bone-Implant Interface; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010027:Osteotomy / Q000379:methods*; D019736:Prostheses and Implants; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging* / Q000601:surgery*; D016896:Treatment Outcome
keywords: Knee; Orthopedic operative procedures