This week’s Orthopaedic Crossfire® debate was part of the 19th Annual Current Concepts in Joint Replacement® (CCJR®), Spring meeting, which took place in Las Vegas. This week’s topic is “Porous Metal Cones: Optimal Solution for Bone Deficiency” For is Robert T. Trousdale, M.D., Mayo Clinic, Rochester, Minnesota. Opposing is Thomas P. Sculco, M.D., Hospital for Special Surgery, New York, New York. Moderating is Paul F. Lachiewicz, M.D., Duke University Medical Center, Durham, North Carolina.
Dr. Trousdale: When it comes to the question of cones in revision total knee replacement, the answer is “Yes.”
Cones in revision total knees should be utilized because they’re reliable; at mid-term follow-up they’re durable. They’re relatively easy to do. And relatively fast to do compared to allografts. And I think it may solve a major problem in revision knee surgery (fixation).
The rate of revision knee surgeries is increasing and it’s estimated to rise over 600% (Kurtz et al., JBJS 2007) over the next 20 years or so. Aseptic loosening in the revision setting still remains a major, major problem, approximately 1/3 of revision TKAs (Lombardi et al., BJJ 2014).
What are the options for metaphyseal fixation? Do you use cement alone? Do you use cement with allograft? Or you can use metaphyseal sleeves or cones to fill in the defects.
With small defects, anything works. You can cement. You can use graft. You can use sleeves or cones. In small defects, it’s really a chip shot. I choose to use a small chunk of allograft, Steinmann pins, and a cemented stem to bypass small, very manageable defects.
The problem lies with the big defects. Do we use allografts or cones and/or sleeves? Today, the vast majority of my patients are getting either a cone or a sleeve for these big defects.
Traditionally, they’ve been dealt with, with large structural allografts. There are concerns with availability, disease transmission and I’ve found these relatively difficult to prepare and ensure good host contact against the bone. The mid-term results of allografts, both in this series as well as our experience, have been a little bit humbling. Ten years, 72% survivorship of these big, bulk allografts (Clatworthy et al., JBJS Am. 2001). I think we can do better.
Metaphyseal sleeves or cones—they come in a lot of different sizes—are easier than allograft. They allow for immediate weight-bearing if you cement the component around them. You can use cemented or cementless designs if you wish. There are a lot of different surface finishes and companies that make these types of implants.
The cones…I use them in large metaphyseal defects, whether it’s segmental or cavitary, where historically I would have used an allograft.
