Master Techniques in Orthopedic Surgery Knee CH21

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PART IV Revision Total Knee Arthroplasty

FIGURE 21-6. In each knee system, a variety of trial tibial augments are available including blocks and wedges of varying thicknesses.

FIGURE 21-7. Some type I and smaller type IIA defects may be treated with a system-specific metal sleeve.

Commercially pure tantalum is formed into a porous trabecular geometry that approximates the structure of cancellous bone. 14-16 TM has two to three times the porosity of conventional porous metal coatings, which helps maximize the potential for bone ingrowth. 14-16 In addition, owing to its inherent strength, it may be used without the need for conventional metal backing to create structural augments. Widespread use in many areas of orthopedic reconstruction has demonstrated the rapid manner in which osseous ingrowth into this tantalum substrate occurs. 14-16 Porous titanium cones are currently available from two manufacturers and are produced using different technology. A newly released cone system with 3D printed titanium (Tritanium; Stryker)

FIGURE 21-8. Tantalum cones are used independently of the prosthesis to reconstruct metaphyseal bone loss in the tibia or femur. A stepped tibial cone is demonstrated before implantation.

FIGURE 21-9. Three-dimensional printed titanium cones are also used independently of the prosthesis. However, the recently released system is based on an intramedullary guided milling system.