Is the ACL necessary for a successful total knee arthroplasty (replacement)?

Recently, due to advertising, there has been considerable discussion about keeping the anterior cruciate ligament (ACL) in total knee arthroplasty (replacement). The item being advertised is a tibial (lower part of leg) component that is shaped like a horseshoe and allows the surgeon to retain the ACL. The surgeons at OSMS do the most total knee replacements in the region and this is a question that is asked frequently.

So, is it necessary to keep the ACL? Here is our take:

Arthritis & Support. In most severely arthritic knees, the ACL is torn or absent from degeneration. Therefore, the great majority of total knee designs the last 20-25 years have routinely removed the ACL even if present. The design and shape of the artificial components in these knee designs essentially take over for the ACL and provide the necessary stability in the knee.

Long Term Survivorship. It is known that by replacing the knee with artificial components, the kinematics (how the bones move in relation to each other) can dramatically change. Therefore altering this movement by keeping the ACL may have an undesired effect on long term survivorship of the replacement depending on the type of knee components used.

Past Outcomes. Interestingly, in the beginning of total knee arthroplasty, many designs tried to keep the ACL with this horseshoe design, but failed due to premature breaking and wear of the tibial component. The newer designs uses newer materials to make the component stronger, but long term studies looking at survivorship still are yet to come.

With all of that being said, this still may be a concept that is appropriate for the right individual, but would require a discussion and exam by an orthopedic surgeon who is extremely knowledgeable and skilled in total knee arthroplasty.