title: Repair of a chondral defect using a cell free scaffold in a young patient--a case report of successful scaffold transformation and colonisation.
abstract: BACKGROUND
  Chondral defects of the articular surface are a common condition that can lead to osteoarthritis if not treated. Therapy of this condition is a topic of constant debate and a variety of chondral repair strategies are currently used. One strategy involves implantation of a cell-free matrix of type I collagen (COL1), to provide a scaffold for chondrocyte migration and proliferation and extracellular matrix production. Although several studies have suggested that chondrocytes can move, to the best of our knowledge there is still no proof of chondrocyte occurrence in a former cell-free scaffold for articular cartilage repair in humans.
  
  
  METHODS
  An 18-year-old male patient underwent arthroscopic surgery of the knee for patellar instability and a chondral defect of the femoral condyle. Clinical outcome scores were recorded pre-operatively, after 6 weeks and after 6, 12, 24 and 36 months. MRI was recorded after 6 weeks and after 6, 12, 24 and 36 months postoperatively. At 42 months after implantation of a cell-free type I collagen matrix and reconstruction of the medial patellofemoral ligament, the patient was again treated arthroscopically for a tear of the medial meniscus of the same knee. A biopsy of the previous chondral defect was taken during arthroscopy for histological examination.
  
  
  CONCLUSIONS
  In addition to good clinical and radiological results reported for cell-free scaffolds for cartilage repair in several other studies, transformation of the scaffold could be observed during re-arthroscopy for the meniscal tear. Histological examination of the specimen revealed articular cartilage with vital chondrocytes and a strong staining reaction for type II collagen (COL II), but no reaction for type I collagen staining. This might indicate a complete transformation of the scaffold and supports the theory that cell free scaffolds could support cell migration. Although the cell source remains unclear, migrating chondrocytes from the periphery remain a possibility.
authors.affiliation: Department of Orthopedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, Marburg 35043, Germany.
authors.forename: Karl F
authors.initials: KF
authors.lastname: Schüettler
authors.forename: Johannes
authors.initials: J
authors.lastname: Struewer
authors.forename: Marga B
authors.initials: MB
authors.lastname: Rominger
authors.forename: Peter
authors.initials: P
authors.lastname: Rexin
authors.forename: Turgay
authors.initials: T
authors.lastname: Efe
mesh_terms: D000293:Adolescent; D001182:Arthroscopy / Q000379:methods*; D002357:Cartilage Diseases / Q000378:metabolism / Q000473:pathology / Q000601:surgery*; D002465:Cell Movement / Q000502:physiology; D002474:Cell-Free System / Q000378:metabolism / Q000473:pathology; D019902:Chondrocytes / Q000166:cytology / Q000378:metabolism / Q000637:transplantation*; D024042:Collagen Type I / Q000008:administration & dosage / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D016896:Treatment Outcome
chemical_list: D024042:Collagen Type I