1. a Department of Polymer Technology, The Royal Institute of Technology, 10044 Stockholm, Sweden
2. b Department of Polymer Technology, The Royal Institute of Technology, 10044 Stockholm, Sweden
3. c Department of Experimental Research and Department of Orthopedics, University of Lund, Malmö General Hospital, 21401 Malmö, Sweden
4. d Department of Experimental Research and Department of Orthopedics, University of Lund, Malmö General Hospital, 21401 Malmö, Sweden