1. Department of Orthopedic Surgery, University Hospital Maastricht, The Netherlands.
2. IsoTis Orthobiologics, MB Bilthoven, The Netherlands.
3. Department of BMI, Twente University, MB Bilthoven, The Netherlands.
4. Present address, Department of Orthopedic Surgery, Groningen University Medical Center, Groningen, The Netherlands.
5. Present address, Department of Biomedical Engineering, Groningen University Medical Center, Groningen, The Netherlands.
6. Present address, CellCoTec, Bilthoven, The Netherlands.