title: Changes in articular cartilage after meniscectomy and meniscus replacement using a biodegradable porous polymer implant.
abstract: OBJECTIVE
  To evaluate the long-term effects of implantation of a biodegradable polymer meniscus implant on articular cartilage degeneration and compare this to articular cartilage degeneration after meniscectomy.
  
  
  METHODS
  Porous polymer polycaprolacton-based polyurethane meniscus implants were implanted for 6 or 24 months in the lateral compartment of Beagle dog knees. Contralateral knees were meniscectomized, or left intact and served as controls. Articular cartilage degeneration was evaluated in detail using India ink staining, routine histology, immunochemistry for denatured (Col2-¾M) and cleaved (Col2-¾C(short)) type II collagen, Mankin's grading system, and cartilage thickness measurements.
  
  
  RESULTS
  Histologically, fibrillation and substantial immunohistochemical staining for both denatured and cleaved type II collagen were found in all three treatment groups. The cartilage of the three groups showed identical degradation patterns. In the 24 months implant group, degradation appeared to be more severe when compared to the 6 months implant group and meniscectomy group. Significantly more cartilage damage (India ink staining, Mankin's grading system, and cartilage thickness measurements) was found in the 24 months implant group compared to the 6 months implant group and meniscectomy group.
  
  
  CONCLUSIONS
  Degradation of the cartilage matrix was the result of both mechanical overloading as well as localized cell-mediated degradation. The degeneration patterns were highly variable between animals. Clinical application of a porous polymer implant for total meniscus replacement is not supported by this study.
authors.affiliation: Orthopaedic Research Lab, Department of Orthopaedics, Radboud University Nijmegen Medical Centre, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands. g.hannink@orthop.umcn.nl
authors.forename: Gerjon
authors.initials: G
authors.lastname: Hannink
authors.forename: Tony G
authors.initials: TG
authors.lastname: van Tienen
authors.forename: Arend Jan
authors.initials: AJ
authors.lastname: Schouten
authors.forename: Pieter
authors.initials: P
authors.lastname: Buma
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001707:Biopsy, Needle; D002358:Cartilage, Articular / Q000473:pathology*; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D007150:Immunohistochemistry; D020007:Implants, Experimental; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D008592:Menisci, Tibial / Q000473:pathology / Q000601:surgery*; D019637:Orthopedic Procedures / Q000379:methods; D011108:Polymers; D016062:Porosity; D011474:Prosthesis Design; D011897:Random Allocation; D018709:Statistics, Nonparametric
chemical_list: D011108:Polymers
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