ELSEVIER 0267-6605(94)00009-3 Clinical Materials 16 (1994) 201-210 © 1994 Elsevier Science Limited Printed in Great Britain. All rights reserved 0267-6605/94/$7.00 Human Osteoblast Response to PTFE Surfaces W. R. Walsh, * M. Olmedo, H. D. Kim, L. Zou & A.-P. C. Weiss Department of Orthopaedics, Brown University, Biomechanics Laboratory and Hand-Microsurgical Laboratory, Rhode Island Hospital, Providence, RI 02903, USA (Received 6 June 1994; sent for revision 29 July 1994; accepted 19 August 1994) Abstract: Recently, expanded polytetrafluoroethylene (ePTFE, Gortex) vascular grafts have been rolled and used for interpositional arthroplasties of the carpus in the wrist. Little data, however, are available on the response of human osteo- blasts to ePTFE. In-vitro cell culture is a useful method to determine initial cell-biomaterial interactions. The present study explores the morphological and mitogenic response of human bone cells cultured on vascular grade ePTFE grafts. The present findings suggest that neither the inner nor the outer surface of ePTFE, in its present form, support osteoblast growth. PTFE may be a suitable material to act as a space filler for carpal bone interpositional arthroplasties. INTRODUCTION Anatomical, clinical, functional and biomechanical requirements have motivated the development of biomaterials and prosthetic devices for a number of soft tissue (vascular, skin, ligament prosthetics) and hard tissue (total joint replacements, bone sub- stitutes) applications. A greater understanding of cell-material surface interactions has become increasingly important in the development and modification of existing materials for new clinical applications. One example involves prosthetic replacements for bones of the carpus, most com- monly the trapezium, in the treatment of traumatic or degenerative disorders of the wrist which has become an essential component of hand surgery today. Biomaterials used for carpal bone replacements need to provide pain relief and allow normal load transmission for proper wrist kinematics. Arthro- plasty of the carpal bones with silicone rubber implants has been used clinically since 1965. 1 More than 130000 patients in 83 countries have * To whom correspondence should be addressed at: Centre for Biomedical Engineering, University of New South Wales, Syd- ney, NSW 2052, Australia. 201 had silicone implant arthroplasty of carpal bones with successful pain relief and increased function. I However, recent long-term studies have demon- strated failure of silicone carpal bone replacements and the presence of wear debris, apparently due to fragmentation from repeated cyclical loading. 1 Sili- cone has also been implicated as a causative agent of one type of particular synovitis. Silicone parti- cles, however, are not affected by the lysosomal enzymes in a normal macrophage foreign body giant cell response. 1 The silicone particles may be 'regurgitated' and the unused enzymes released into the joint space inducing a reactive synovitis. 1 Recently, rolled vascular grafts of expanded poly- tetrafluoroethylene (ePTFE, Gortex, W. L. Gore and Assoc. Flagstaff, AZ) have been used clinically for interpositional arthroplasty of the carpometa- carpal joint. PTFE has also been successfully applied as a vascular graft due to its strength, flexi- bility and bioinertness.' The mechanical properties and biocompatibility of PTFE may lend itself as an ideal material for use as carpal bone replace- ments. The ability of PTFE to function as a carpal bone replacement requires an understanding of cell-biomaterial interactions and whether or not osteoblasts have an affinity to PTFE. Long-term use of PTFE in this type of arthroplasty may