Metaphyseal cones in Revision Total Knee Arthroplasties (TKAs)

Message from Matthew P. Abdel, MD

Rochester, MN 

Aseptic loosening continues to be a common cause of failure after primary total knee arthroplasty (TKA), with several series showing it to be the most common cause after chronic periprosthetic joint infection (PJI)1. Frequently, aseptic loosening of the femur and/or tibia results in substantial bone loss, and thus compromised fixation in the revision setting2. Over the past decade, several advances have contributed to the improving success of revision TKAs. Arguably, one of the greatest improvements has been the innovation of metaphyseal fixation, particularly metaphyseal cone augments. Metaphyseal fixation has numerous benefits, including the ability to address bone loss while simultaneously improving long-term fixation through biologic fixation2.

Early generations of metaphyseal cones were limited by cone sizes and geometries, combined with a difficult preparation that was often time-consuming. As such, there may be a risk of intraoperative periprosthetic fracture when impacting the final cone. However, Stryker raised the bar in 2015 with the introduction of the Triathlon Tritanium Cone Augments for both the femur (Slide 1) and tibia (Slide 2)3.

In my opinion, there are several benefits to Stryker’s Triathlon Tritanium Cone Augments that deserve particular attention. Foremost, the additive manufactured technology allows for a host of sizes and geometries to be produced with Tritanium, a highly porous metal with biologic fixation technology. This is essential as symmetric (Slide 3) and lobe-shaped cones (Slide 4) are now available for the tibia. This allows the surgeon to address Anderson Orthopedic Research Institute (AORI) type IIA (Slide 5) and IIB (Slide 6) or III defects. Moreover, the design of the femoral cone allows for AORI type II (Slide 7) and III defects to be managed without removing a large amount of bone4. Second, in my opinion, the preparation is facile, safe, and saves substantial time intraoperatively. Based on an intramedullary guided milling system (Slide 8), a precise bony preparation may be completed and allow for an optimized bony apposition without the need for bone fillers.

Given the above, it is my preference to use Stryker’s Triathlon Tritanium Cone Augments on both the femur and tibia for all revision TKAs, particularly those with increased levels of constraint. Since I have found the preparation requires virtually no extra time, and I find it to be very precise with the milling system, I am inclined to address bone defects with Stryker’s Triathlon Tritanium Cone Augments, while also gaining the potential of long-term biologic fixation. While cemented or uncemented stems may be utilized with the cones, it is my preference to utilize short to mid-length cemented stems (Slide 9). Not only do I believe this allows for the local delivery of antibiotics and adjustments to deformed bony anatomy, but I believe it also allows for immediate rigid fixation, promoting biologic fixation of the cones.



  1. Abdel MP, Ledford CK, Kobic A, Taunton MJ, Hanssen AD. Contemporary failure aetiologies of the primary, posterior-stabilised total knee arthroplasty. Bone Joint J. 2017 May;99-B(5):647-652.
  2. Sculco PK, Abdel MP, Hanssen AD, Lewallen DG. The management of bone loss in revision total knee arthroplasty: rebuild, reinforce, and augment. Bone Joint J. 2016 Jan;98-B(1 Suppl A):120-4.
  3. Faizan A1, Bhowmik-Stoker M1, Alipit V1, Kirk AE1, Krebs VE2, Harwin SF3, Meneghini RM. Development and Verification of Novel Porous Titanium Metaphyseal Cones for Revision Total Knee Arthroplasty. J Arthroplasty. 2017 Jun;32(6):1946-1953.
  4. Leibowitz E, Lipschutz D, Soliman M, Meneghini M. Virtual Bone Analysis Determines Metaphyseal Augment Fit. ORS 2015 Meeting Poster.