This week’s Orthopaedic Crossfire® debate was part of the 33rd Annual Current Concepts in Joint Replacement® (CCJR®), Winter meeting, which took place in Orlando. This week’s topic is “The Bi-Cruciate Retaining Knee: A Bridge Too Far.” For is Mark W. Pagnano, M.D., Mayo Clinic, Rochester, Minnesota. Opposing is Adolph V. Lombardi, Jr., M.D., Mt. Carmel New Albany Surgical Hospital, New Albany, Ohio. Moderating is Thomas P. Sculco, M.D., Hospital for Special Surgery, New York, New York.
Moderator Sculco: This debate is sort of a throw-back topic. We’re going to talk bi-cruciate total knee replacement. And, we have an all Italian panel here. Pagnano, Lombardi and Sculco—with Mark Pagnano taking the negative side of using the bi-cruciate.
Dr. Pagnano: Thanks very much Tom. It is a pleasure to discuss the bi-cruciate retaining total knee replacement—which remains a bridge too far.
You and I as surgeons certainly want to make knee replacement operations reliable, reproducible and durable as we alleviate pain and improve function for our patients whether we use total knee replacement or partial knee replacement.
Total knee replacement, thankfully, has proved quite durable over the last several decades. Some implants do a little bit better. Some surgeons and institutions do a little bit better. But overall knee replacement is a durable operation.
In the last five years, much of the focus in the academic circles has shifted to function after total knee replacements with an interest in eliminating the so-called satisfaction gap, recognizing that some percentage of total knee replacement patients are not quite satisfied with their knee.
Surgeons have many thoughts on how to improve that function. Some focus on alignment. Better alignment goals and whether enabling technology like navigation or robotics might help. Others focus on advanced ligament balancing concepts, like sensor/tensor devices. We’re here to discuss ACL [anterior cruciate ligament] and PCL [posterior cruciate ligament] preserving total knees. And at the other end of the design spectrum are implants that provide guided motion, like ACL/PCL substituting total knee replacements.
Bi-cruciate retaining total knee replacement is conceptually appealing. Its appeal typically comes from references to the uni-compartmental knee. With the uni-compartmental knee, we know you can see better motion, quicker recovery, and movement closer to normal kinematics. Many surgeons assume that is because you save the ACL and the PCL. There’s no doubt that is happening. But in a uni-compartmental knee, things are markedly different than an ACL/PCL preserving total knee.
I think it’s a logical fallacy to assume that an ACL/PCL retaining total knee replacement will approximate the results of a uni-compartmental knee. A uni is really much, much less than one-third of a total knee replacement.
Think about the complex three-dimensional architecture of a knee, the joint contour, the trochlea, the transition zones, the offset. In a uni-compartmental knee, the only thing you’re changing is the joint surface. All other factors stay the same.
As soon as we switch to a total knee replacement, every one of those complex three-dimensional architecture elements is going to change.
Some have already recognized this (Saxena et al, Knee 2016) and are working on 3-D MRI analysis that looks at the tibia and shows that due to the highly variable proximal tibial topography, a monoblock, bi-cruciate baseplate is not likely to reproduce normal anatomy.
I’m sure Dr. Lombardi will review some of the retrospective data. Cloutier has a long-term follow-up of his individual series and showed the survivorship about the same as a standard total knee. And Pritchett had some data on bi-cruciate versus posterior cruciate retaining knees. Again, similar survival and a little bit of a preference for a bi-cruciate in some of the patients.
