title: Graft hypertrophy of matrix-based autologous chondrocyte implantation: a two-year follow-up study of NOVOCART 3D implantation in the knee.
abstract: OBJECTIVE
  Graft hypertrophy is a major complication in the treatment for localized cartilage defects with autologous chondrocyte implantation (ACI) using periosteal flap and its further development, Novocart (a matrix-based ACI procedure). The aim of the present study is to investigate individual criteria for the development of graft hypertrophy by NOVOCART 3D implantation of the knee in the post-operative course of 2 years.
  
  
  METHODS
  Forty-one consecutive patients with 44 isolated cartilage defects of the knee were treated with NOVOCART 3D implants. Individual criteria and defect-associated criteria were collected. Follow-up MRIs were performed at 3, 6, 12 and 24 months. The NOVOCART 3D implants were measured and classified. The modified MOCART Score was used to evaluate quality and integration of the NOVOCART 3D implants in MRI.
  
  
  RESULTS
  Graft hypertrophy was observed in a total of 11 patients at all post-operative time points. We were able to show that NOVOCART 3D implantation of cartilage defects after acute trauma and osteochondritis dissecans (OCD) led to a significantly increased proportion of graft hypertrophy. No other individual criteria (age, gender, BMI) or defect-associated criteria (concomitant surgery, second-line treatment, defect size, fixation technique) showed any influence on the development of graft hypertrophy. The modified MOCART Score results revealed a significant post-operative improvement within 2 years.
  
  
  CONCLUSIONS
  The aetiology of cartilage defects appears to have a relevant influence for the development of graft hypertrophy. Patients, who were treated with NOVOCART 3D implants after an acute event (acute trauma or OCD), are especially at risk for developing a graft hypertrophy in the post-operative course of two years.
  
  
  METHODS
  Case series, Level IV.
authors: Department of Orthopaedic Surgery, University Hospital of Munich (LMU), Campus Großhadern, Marchioninistr. 15, 81377, Munich, Germany, thomas.niethammer@med.uni-muenchen.de.
authors: Thomas R
authors: TR
authors: Niethammer
authors: Matthias F
authors: MF
authors: Pietschmann
authors: Annie
authors: A
authors: Horng
authors: Björn P
authors: BP
authors: Roßbach
authors: Andreas
authors: A
authors: Ficklscherer
authors: Volkmar
authors: V
authors: Jansson
authors: Peter E
authors: PE
authors: Müller
mesh_terms: D000328:Adult; D000368:Aged; D019902:Chondrocytes / Q000637:transplantation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006984:Hypertrophy; D007592:Joint Diseases / Q000209:etiology / Q000601:surgery*; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D014182:Transplantation, Autologous / Q000009:adverse effects*; D055815:Young Adult