title: Characteristic complications after autologous chondrocyte implantation for cartilage defects of the knee joint.
abstract: BACKGROUND
  Although autologous chondrocyte implantation (ACI) is a well-established therapy for the treatment of isolated cartilage defects of the knee joint, little is known about typical complications and their treatment after ACI.
  
  
  OBJECTIVE
  Unsatisfactory outcome after ACI is associated with technique-related typical complications.
  
  
  METHODS
  Case series; Level of evidence, 4.
  
  
  METHODS
  A total of 309 consecutive patients with 349 ACI procedures of the knee joint were analyzed. Three different ACI techniques were used: periosteum-covered ACI in 52 cases (14.9%), Chondrogide (Geistlich Biomaterials, Wolhusen, Switzerland) membrane-covered ACI in 215 cases (61.6%), and a 3-dimensional matrix-associated ACI (BioSeed-C, Biotissue Technologies, Freiburg, Germany) in 82 cases (23.5%). In 52 patients, revision surgery was performed for persistent clinical problems. These patients were analyzed for defect size and location, technique of ACI, and intraoperative findings during revision surgery. The mean time of follow-up for patients after ACI was 4.5 years (standard deviation, +/- 1.5).
  
  
  RESULTS
  Four typical major complications were identified: hypertrophy of the transplant, disturbed fusion of the regenerative cartilage and the healthy surrounding cartilage, insufficient regenerative cartilage, and delamination. These diagnoses covered a total of 88.5% of the patients who underwent revision surgery. The overall complication rate was highest in the group of patients treated with periosteum-covered ACI (P = .008). The incidence of symptomatic hypertrophy was 5.2% for all techniques and defect locations; the highest incidence was in patients treated with periosteum-covered ACI (15.4%) (P = .001). The incidence of disturbed fusion was highest in the Chondrogide-covered ACI (3.7%) and the matrix-associated ACI group (4.8%). Concerning the incidence of complications by defect location, there was a tendency for increased complications in patellar defects (P = .095). Within the patellar defects group, no correlation was found for the occurrence of delamination, insufficient regeneration, and disturbed fusion. As a statistical trend, an increased rate of hypertrophy was found for patellar defects (P = .091).
  
  
  CONCLUSIONS
  A major proportion of complications after ACI can be summarized by 4 major diagnoses (symptomatic hypertrophy, disturbed fusion, delamination, and graft failure). Among those, the overall complication rate and incidence of hypertrophy of the transplant were higher for periosteum-covered ACI. Furthermore, an increased rate of symptomatic hypertrophy was found for patellar defects. Therapeutic concepts need to be developed to treat these typical complications of ACI.
authors.affiliation: Department of Orthopaedic Surgery and Traumatology, Freiburg University Hospital, Freiburg im Breisgau, Germany. philipp.niemeyer@uniklinik-freiburg.de
authors.forename: Philipp
authors.initials: P
authors.lastname: Niemeyer
authors.forename: Jan M
authors.initials: JM
authors.lastname: Pestka
authors.forename: Peter C
authors.initials: PC
authors.lastname: Kreuz
authors.forename: Christoph
authors.initials: C
authors.lastname: Erggelet
authors.forename: Hagen
authors.initials: H
authors.lastname: Schmal
authors.forename: Norbert P
authors.initials: NP
authors.lastname: Suedkamp
authors.forename: Matthias
authors.initials: M
authors.lastname: Steinwachs
mesh_terms: D000328:Adult; D002356:Cartilage / Q000473:pathology / Q000601:surgery*; D019902:Chondrocytes / Q000637:transplantation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000473:pathology / Q000601:surgery*; D008297:Male; D016378:Tissue Transplantation / Q000009:adverse effects*; D014182:Transplantation, Autologous; D017211:Treatment Failure; D016896:Treatment Outcome; D055815:Young Adult