KNEE Chondroprotective effects of a polycarbonate-urethane meniscal implant: histopathological results in a sheep model Gal Zur • Eran Linder-Ganz • Jonathan J. Elsner • Jonathan Shani • Ori Brenner • Gabriel Agar • Elliott B. Hershman • Steven P. Arnoczky • Farshid Guilak • Avi Shterling Received: 25 January 2010 / Accepted: 23 June 2010 / Published online: 16 July 2010 Ó Springer-Verlag 2010 Abstract Purpose Injury or loss of the meniscus generally leads to degenerative osteoarthritic changes in the knee joint. However, few surgical options exist for meniscal replace- ment. The goal of this study was to examine the ability of a non-degradable, anatomically shaped artificial meniscal implant, composed of Kevlar Ò -reinforced polycarbonate- urethane (PCU), to prevent progressive cartilage degener- ation following complete meniscectomy. Methods The artificial meniscus was implanted in the knees of mature female sheep following total medial meniscectomy, and the animals were killed at 3- and 6-months post-surgery. Macroscopic analysis and semi- quantitative histological analysis were performed on the cartilage of the operated knee and unoperated contralateral control joint. Results The PCU implants remained well secured throughout the experimental period and showed no signs of wear or changes in structural or material properties. His- tological analysis showed relatively mild cartilage degen- eration that was dominated by loss of proteoglycan content and cartilage structure. However, the total osteoarthritis score did not significantly differ between the control and operated knees, and there were no differences in the severity of degenerative changes between 3 and 6 months post-surgery. Conclusion Current findings provide preliminary evi- dence for the ability of an artificial PCU meniscal implant to delay or prevent osteoarthritic changes in knee joint following complete medial meniscectomy. Keywords Meniscus Á Synthetic Á Meniscectomy Á Animal model Á Allograft Introduction The menisci play an important role in knee joint biome- chanics. Clinical studies have shown that the loss of meniscus function, most often as a result of meniscal tear, leads to degenerative arthritis, presumably due to changes in cartilage load distribution [3, 15, 25]. In these cases, there is clearly a need to protect the articular cartilage by either repairing or replacing the meniscus. However, meniscal replacement still represents an unsolved problem in orthopedics. While meniscal allografts have been shown to heal to the capsule and relieve pain [40], their use is limited due to problems with availability, size matching, G. Zur and E. Linder-Ganz contributed equally to this work. G. Zur Á E. Linder-Ganz (&) Á J. J. Elsner Á J. Shani Á O. Brenner Á A. Shterling Research and Development Center, Active Implants Corporation, P.O. Box 8395, 42505 Netanya, Israel e-mail: eran.ganz@activeimplants.com G. Agar Department of Orthopedic Surgery, Assaf Harofe Medical Center, Zeriffin, Israel E. B. Hershman Department of Orthopaedic Surgery, Lenox Hill Hospital, New York, NY, USA S. P. Arnoczky Laboratory for Comparative Orthopaedic Research, College of Veterinary Medicine, Michigan State University, East Lansing, MI, USA F. Guilak Departments of Surgery and Biomedical Engineering, Duke University Medical Center, Durham, NC, USA 123 Knee Surg Sports Traumatol Arthrosc (2011) 19:255–263 DOI 10.1007/s00167-010-1210-5