The four ligaments.
Four main ligaments hold the knee together and control how it moves:
- Anterior cruciate ligament (ACL). Runs through the centre of the knee and stops the shin bone sliding forwards and rotating excessively. The one most often injured in sport.
- Posterior cruciate ligament (PCL). Stops the shin bone sliding backwards. Injured less often, typically by a direct blow to the front of the bent knee, including dashboard injuries.
- Medial collateral ligament (MCL). On the inner side, resisting force from the outside. The most commonly injured knee ligament overall, and the one that most reliably heals without surgery.
- Lateral collateral ligament (LCL) and the posterolateral corner. On the outer side. Less commonly injured in isolation and more significant when it is, because untreated posterolateral injury compromises other reconstructions.
Why this page is on a joint replacement site.
Professor Rodda does not reconstruct ligaments. The reason this condition matters here is what happens later.
A knee that has torn its ACL has a substantially increased risk of osteoarthritis over the following two to three decades, whether or not it was reconstructed. Part of that is the initial impact injury to the cartilage at the moment of rupture, part is the meniscal damage that frequently accompanies it, and part is the altered mechanics of a knee that has been unstable. Removing meniscal tissue at the time compounds it.
The practical consequence is a group of patients presenting with significant knee arthritis in their forties and fifties following a sporting injury twenty or thirty years earlier. That group is younger than the typical arthritis patient, which changes the conversation about timing, about implant longevity and about the likelihood of eventual revision.
Ligament injury and knee replacement.
Two things follow from a previous ligament injury when a knee replacement is eventually considered.
First, a deficient ACL rules out most partial knee replacements. A partial replacement relies on the cruciate ligaments to control the knee, so an absent or non-functioning ACL is a contraindication in most designs.
Second, previous surgery changes the planning. Retained fixation devices from a reconstruction may need removing, tunnels from previous grafts can affect where components sit, and prior incisions influence the approach. This is discussed and planned specifically rather than discovered during the operation.
If the injury is recent.
An acute ligament injury needs assessing by a knee surgeon who does sports and ligament work, not by a joint replacement practice. Referral will be redirected accordingly, and the window for meniscal repair in particular is time-sensitive.
Where this practice fits.
Professor Rodda's practice is focused on hip and knee replacement. He does not perform joint-preserving surgery such as arthroscopy or osteotomy. If your condition is at a stage where preservation surgery is the right option, you will be told that and referred to a colleague who does it, within Sunshine Coast Orthopaedic Group or elsewhere. Where the joint has reached the point that replacement is the reasonable option, that is the work done here.
Common questions.
Does an ACL tear always cause arthritis?
Not always, but the risk of osteoarthritis in that knee over the following two to three decades is substantially higher than in an uninjured knee. Associated meniscal damage, and removal of meniscal tissue, increase the risk further.
Does reconstructing the ACL prevent arthritis?
Reconstruction restores stability and allows return to pivoting sport, but the evidence that it prevents later osteoarthritis is not strong. Much of the cartilage injury happens at the moment of rupture.
Can I have a partial knee replacement if my ACL is gone?
Usually not. A partial knee replacement relies on the cruciate ligaments to control the knee, so a deficient ACL is a contraindication for most designs. A total knee replacement is the appropriate operation.
Will my old ACL screws need to come out?
Sometimes. Retained fixation can sit where a component or a stem needs to go. It is identified on pre-operative imaging and planned for, including having the correct removal instruments available.
I have just injured my knee. Is this the right practice?
Not for an acute ligament injury. That needs a knee surgeon who does sports and ligament work, and some decisions, particularly about meniscal repair, are time-sensitive. Your referral will be redirected.
References.
- Lohmander LS, Englund PM, Dahl LL, Roos EM. The long-term consequence of anterior cruciate ligament and meniscus injuries: osteoarthritis. Am J Sports Med. 2007;35(10):1756-1769.
- Filbay SR, Grindem H. Evidence-based recommendations for the management of anterior cruciate ligament (ACL) rupture. Best Pract Res Clin Rheumatol. 2019;33(1):33-47.
This page provides general information about a medical condition and a surgical procedure. It is not individual medical advice and does not replace consultation with a qualified practitioner. Outcomes vary between individuals and all surgery carries risk. A referral is needed for a consultation with Professor Daevyd Rodda; without one, you can start with the practice nurse practitioner, who can provide it.