Medial Collateral Ligament (MCL) Injury
What Is a Medial Collateral Ligament (MCL) Injury?
The medial collateral ligament (MCL) is one of the four main ligaments of the knee; it runs from the femur to the inner side of the tibia and stabilises the knee against opening inwards (valgus). An MCL injury occurs when this ligament is stretched beyond its normal limit.
The MCL is one of the most commonly injured ligaments in the knee. Because it has a good blood supply, most injuries heal without surgery; however, severe tears and injuries in which other ligaments are also affected are handled differently. For surgical options you can review the MCL reconstruction page, and for the ligament structures of the knee the knee ligament tear page.
How Does It Happen? Risk Factors
An MCL injury is usually caused by a force that pushes the knee to open inwards. The most typical mechanism is a direct blow to the outer side of the knee; it is common in contact and pivoting sports.
- A blow to the outer side of the knee (contact sports such as football, skiing and wrestling).
- The knee opening inwards during sudden changes of direction, twisting or an awkward landing.
- Inadequate warm-up, fatigue and previous knee injuries raise the risk.
Grades of Injury
MCL injuries are graded into three levels according to the severity of the damage and the laxity it leaves in the knee; this grading guides the treatment plan.
- Grade 1: the ligament is stretched but its integrity is preserved; there is mild pain and tenderness without notable laxity.
- Grade 2: a partial tear; there is inner-side pain, mild-to-moderate laxity and instability under stress.
- Grade 3: a complete tear; there is marked laxity, the knee opens inwards and another ligament injury is often present as well.
Symptoms
Symptoms vary with the grade of injury; in mild cases there is only tenderness on the inner side, while in severe cases there is marked instability.
- Pain and pinpoint tenderness on the inner side of the knee.
- Swelling and, at times, bruising.
- A sense of giving way or unreliability when bearing weight or stressing the knee sideways.
- A feeling of tearing or a pop on the inner side at the moment of injury.
Conditions That Can Be Confused With It
The MCL is not the only cause of pain on the inner side of the knee; examination tells them apart. An anterior cruciate ligament injury tends to cause giving way at the moment of twisting and usually rapid swelling, whereas in an MCL injury the pain and laxity are localised to the inner side.
A tear of the inner meniscus also causes inner-side pain and, at times, locking; an MCL and a meniscus injury sometimes occur together. In a severe valgus injury a multiligament injury affecting more than one structure is kept in mind, and this changes the treatment.
Diagnosis: Examination and Imaging
Diagnosis begins with the history and physical examination. A valgus stress test applied to the inner side of the knee assesses laxity and pain; the other ligaments and the meniscus are also checked.
X-rays are used to exclude bone injuries; MRI is the most valuable study for showing the grade of ligament damage and any accompanying meniscus or cruciate ligament injury. This clarifies whether the injury is isolated or part of a multiligament injury.
Non-Surgical Treatment
Most isolated MCL injuries, regardless of grade, heal without surgery because the ligament's blood supply and healing capacity are good. The aim of treatment is to reduce pain and swelling and then to return the knee gradually to load and movement while protecting the ligament.
- Controlling pain and swelling in the early period and, where needed, restricted weight-bearing with crutches.
- Allowing controlled movement while protecting the ligament in a hinged brace.
- Physiotherapy aimed at range of motion, then progressive strengthening and balance.
When Is Surgery Needed?
Surgery is rarely needed in isolated MCL injuries. Valgus instability that persists despite non-surgical treatment, certain injury patterns unfavourable for healing and multiligament injuries bring surgery onto the agenda.
In these situations a repair or graft reconstruction is performed according to the type of injury; the details are on the MCL reconstruction page. If another ligament such as the ACL or PCL is also injured, the surgical plan is made accordingly.
Recovery and Return to Sport
Recovery time varies with the grade of injury; mild injuries settle within a few weeks, while severe tears can take longer. Throughout the process a programme that progresses within the limits of pain is followed.
Return to sport is guided by criteria rather than a fixed date: pain-free full range of motion, muscle strength close to the other leg, stability against valgus stress and controlled change-of-direction quality. An early, forced return increases the risk of re-injury.
Prevention
Some MCL injuries, especially in athletes, can be reduced with preparation and technique. The aim is to make the knee more resilient to sudden valgus stress.
- Regular strengthening of the thigh, hip and trunk muscles and balance work.
- Learning correct landing, turning and change-of-direction technique (neuromuscular training).
- Adequate warm-up and rest, and not returning to sport before a previous injury has fully recovered.
When Should You See a Doctor?
Having a knee injury assessed early ensures that cruciate ligament and meniscus injuries that may accompany an MCL injury are not missed.
- After a knee injury there is inner-side pain, swelling and a sense of the knee giving way or being unreliable.
- The knee locks, does not fully straighten and bend, or cannot bear weight.
- Symptoms persist or recur despite non-surgical treatment.
For the assessment of knee ligament injuries you can contact Assoc. Prof. Serkan Sürücü, and you can also review the other conditions covered within knee surgery.