LCS^® Duofix^™

DuoFix™ dual surface coating sets a new standard in natural implant fixation

DuoFix™ dual surface coating adds a new element to the performance of LCS® Complete™. The femoral and tibial components have a dual coating to encourage rapid bone ingrowth and implant stability. DuoFix™ builds on the proven mechanical structure of Porocoat®, Porous Coating* (9, 10) by adding an enhanced biological fixation layer, hydroxyapatite (HA) which acts as a catalyst to osteo-integration. This is applied extensively to cover the fixation interfaces.

Immediate mechanical stability

The unique combination of the DuoFix™ dual surface coating in conjunction with implant design, leads to immediate mechanical stability with accelerated osteointegration of the implant. (11) By minimising micro-motion at the bone implant interface, post-operative pain and early implant failure can be addressed.(12, 13, 14)

Deep bone ingrowth

Porocoat® porous coating is composed of optimally sized pores that allow deep bone ingrowth into its structure.( 17 ). The average pore size is 275 microns. In the DuoFix™ coating, Porocoat® is overlaid with a consistent, ‘line-of-sight’ plasma spray flame application of HA. This bioactive mineral formulation, with a composition similar to that of natural bone, acts as a catalyst for ongrowth, bridging gaps at the interface of up to 2 mm. (18, 19, 20)

Rapid development of a strong corticocancellous interlock

Histological studies show the formation of a dense cortico-cancellous interlock within twelve weeks of implantation, with minimal intervening fibrous tissue. (21, 22) Bone-to-implant shear strength increases progressively over this period, approaching the maximum shear strength of cortical bone.

With more than 30 years of clinical heritage to draw on, LCS® Complete™ DuoFix™ implants set new standards for mobile bearing knee replacement

9. Engh CA, Massin P. Cementless Total Hip Arthroplasty Using the Anatomic Medullary Locking Stem: 0-10 Year Results Using a Survivorship Analysis. Clin Orthop, 249, 1989.

10. Pilliar RM. Powder Metal-made Orthopaedic Implants with Porous Surface for Fixation by Tissue Ingrowth. Clin Orthop, 176, 1983.

11. Oakeshott RD, Komistek RD, Stiehl JB. The A/P Glide Knee Prosthesis - Rationales, Kinematics and Results. LCS Mobile Bearing Knee Arthroplasty. 25 Years of Worldwide Experience. Springer, 2002.

12. Cook SD, Salkeld SL, Patron LP, Barrack RL.
The Effect of Demineralised Bone Matrix Gel on Bone Ingrowth and Fixation of Porous Implants. J Arthroplasty, Vol 17, No 4, 2002.

13. Walsh WR, Kershener J, Zicat B. Micromotion of Cementless Tibial Components: DuoFix and LCS®. Orthopaedic Research Laboratories, Prince of Wales Hospital, Sydney, 1999.

14. Bragdon CR, Burhe D, Lowenstein JD, O’Connor DO, Ramamurit B, Jasty M, Harris WH, Differences in Stiffness of the Interface Between a Cementless Porous Implant and Cancellous Bone In Vivo in Dogs due to Varying Amounts of Implant Motion, J Arthroplasty, 8, 1987.

17. Svehla MJ, Morberg P, Bruce W, Zicat B, Sonnabend DH, Walsh WR. Effect of Surface Preparation on Implant Fixation. Orthopaedic Research Laboratories, Prince of Wales Hospital, Sydney, 2000.

18. Bobyn JD, Pilliar RM, Cameron HU, Weatherley GC. The Optimum Pore Size for the Fixation of Porous-Surfaced Metal Implants by the Ingrowth of Bone. Clin Orthop, 150, 1980.

19. Cook SD, Walsh KA, Haddad RJ. Interface Mechanics and Bone Ingrowth into Porous Co-Cr-Mo Alloy Implants. Clin Orthop, 193, 1985.

20. Bobyn JD, Jacobs JJ, Tanzer M, Urban RM et al. The Susceptibility of Smooth Implant Surfaces to Periimplant Fibrosis and Migration of Polyethylene Wear Debris. Clin Orthop, 311, 1995.

21. Soballe K, Hansen ES, Brocksted-Rasmussen H, et al. Early Fixation of Allogenic Bone Graft in Titanium and Hydroxyapatite Coated Implants. Trans. of the 33rd Annual Meeting, Orthop. Res. Soc 12, 216, 1989.

22. Soballe K, Hansen ES, Brocksted-Rasmussen H, Bünger C. Hydroxyapatite Coating Converts Fibrous Tissue to Bone Around Loaded Implants. J Bone Joint Surg, 75B(2), 270-278, 1993.