What Is The Lateral Collateral Ligament?
The lateral collateral ligament of the knee is one of four major ligaments that help stabilise the knee joint. Also known as the lateral ligament, or the LCL for short is a cord-like ligament situated on the outside (lateral side) of the knee. The lateral ligament connects from its origin above the knee joint at the lateral femoral epicondyle, crossing the knee before inserting into the head of the fibula below the knee joint. Along the way joining the lateral hamstring tendon as it moves towards its insertion attaching to the top of the fibula bone in the lower leg. The function of the LCL fundamentally is to provide stability to the outside of the knee, resisting against varus stress to the knee.
An acute sprain is the most common form of lateral collateral ligament injury, such sprains are relatively uncommon. And when compared to other ligament injuries occurring in the knee, such as an ACL, or MCL sprain of the knee an isolated lateral ligament injury occurs with considerably less frequency. Most lateral ligaments injuries occur in combination with injury to other structures such as the ACL, or PCL and are not common to occur as an isolated injury. In my practice I have seen a few isolated LCL injuries over the years and for me by far the most common trigger was participation in Brazilian jiu jitsu, this however is a personal finding in my practice only.
LCL Injury Is less Common Than An ACL, Or MCL Sprain
The lateral ligament can be vulnerable to injury when the force applied to the knee is too great for the ligament to withstand, and as a result the LCL is overstretched. Such stress can occur with a twisting movement of the knee whilst the foot is fixed, a sharp change in direction, awkward landing from a jump. Most commonly however the LCL is injured in sports through direct impact to the inner surface of the knee. A knee can be exposed to such forces when playing sports like football codes, specifically rugby league, rugby union and American football. In these sports high speed tackles where the players foot is planted on the ground and the opposition player attempts to tackle coming across from the opposite side to the planted foot creating a varus force on impact, potentially stressing the lateral collateral ligament. This varus force puts pressure on the outside of the knee, the lateral collateral ligament, risking stretching, or tearing of the ligament. As mentioned earlier lateral ligament sprains are far less prevalent than medial ligament sprains,
an injury commonly occurring in football codes due to trauma applied to the opposite side of the knee. In this situation the players planted leg during a tackle is on the same side as the opposition player is making their tackle from and on contact the knee is forced inwards towards the other knee, in what is referred to as a “valgus” stress.
Grading Lateral Collateral Ligament Sprain Severity
Lateral ligament sprains as per most ligament injuries can be graded using a basic grading system ranging from Grade 1-3. Where Grade 1 being the most mild injury and Grade 3 being the most severe. Below is further description of the using of the Grade 1-3 ligament injury grading system relevant to the LCL:
Disclaimer: Sydney Physio Clinic provides this information as an educational service and is not intended to serve as medical advice. Anyone seeking specific advice or assistance on Lateral Collateral Ligament Of The Knee Injury should consult his or her general practitioner, sports medicine specialist, orthopedic surgeon, physiotherapist or otherwise appropriately skilled practitioner.
- In a mild, Grade 1 LCL sprain, usually there will be little, or no swelling. There is pain on stress testing the ligament, but no instability of the knee, no assessed laxity. Simply put, the ligament has been stressed but is structurally intact.
- With a Grade 2 LCL sprain the ligament partially tears. In this situation some swelling is common and there may be feelings of instability, potentially the knee will feel to “give-way” with certain movements in a grade 2 sprain. As well as feelings of instability, the knee joint may feel painful and there is often some restriction of movement at least in the early stages post injury. Some local swelling is likely, but no significant generalized swelling and minimal if any bruising.
- A Grade 3 sprain is where the lateral ligament completely tears. This injury is normally associated with swelling and the joint will almost certainly feel unstable. Weight bearing early on can be difficult, however the pain can vary. Noting that, with a complete tear the pain may be actually less than a Grade 2 LCL sprain. Because once the ligament has ruptured as with a Grade 3 sprain then the ligament has already torn as much as it can, so further stress to the area unlike with a Grade 2 sprain can’t cause any further damage to the ligament. Henceforth in this situation a Grade 3 sprain isn’t necessarily more painful than a Grade 2 and may not actually elicit much discomfort once the initial injury mechanism is over. Objectively stress testing the knee with a Grade 3 LCL sprain there is significant joint laxity and this is likely to be subjectively associated with feelings of giving way when the individual attempts to move around on the knee.