Medial Collateral Ligament Injuries of the Knee: Causes, Symptoms, and Treatment
One knee injury that many people are familiar with, especially in contact sports, is a medial collateral ligament (MCL) injury. Despite the prevalence of the injury, many of us don’t know what an MCL injury really is, or what this injury means for the person, their work, or their journey back to the sport or activities they love.
The medial collateral ligament is one of the key ligaments in the knee that helps stabilize the joint and provide support during movement. It runs along the inside of the knee, connecting the bottom of the thigh bone (femur) to the top of the shinbone (tibia).
Injuries to the MCL are relatively common in contact sport, though it's important to note that these may occur during everyday activities as a painful and potentially concerning consequence of accidents, falls and collisions.
In this blog, we will explore the causes, symptoms, treatment, and prevention of medical collateral ligament injuries of the knee, so you can better understand what they mean and what recovery looks like.
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This blog will cover the following topics on MCL Injuries:
- What is an MCL Injury?
- Causes of MCL Injuries
- Symptoms of an MCL Injury
- Diagnosis of MCL Injuries
- Treatment Options for MCL Injuries
- Non Surgical Treatments
- Surgical Treatments
- Prevention of MCL Injuries
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What is an MCL Injury?
An MCL injury occurs when the medial collateral ligament is forcefully over-stretched, causing some or all the ligament fibres to tear. This type of injury typically happens when a high-impact force is applied to the outside of the knee. The other most common mechanism is when the foot is forced outwards relative to the thigh and knee, causing the knee to bend in an unnatural sideways direction.
The severity of the injury can range from a mild sprain to a complete tear, depending on how much the ligament has been damaged.
Grade 1 (Mild):
The ligament is stretched, but typically less than 10% of the fibres are disrupted. These injuries often hurt, although the knee will remain stable.
Grade 2 (Moderate):
The ligament is partially torn, leading to pain, swelling, and some instability in the knee. These injuries range from just a bit more pain and loss of function than a Grade 1, to a near complete tear causing significant instability. You may have difficulty fully extending or bending the knee.
Grade 3 (Severe):
The ligament is completely torn, resulting in significant pain, swelling, and instability of the knee. Walking or putting weight on the injured leg is difficult.
Concurrent Injury:
Due to the traumatic nature of MCL injuries, they can often exist in conjunction with injury to other structures such as the Anterior Cruciate Ligament (ACL), the meniscus, or other ligaments or bony structures in the area.
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Causes of MCL Injuries
MCL injuries are most often caused by direct trauma to the outer side of the knee. This can happen in various ways, including:
- Sporting Injuries: Athletes who participate in contact sports like football, rugby, basketball, and skiing are at high risk of MCL injuries. A collision with another player, a sudden change in direction, or an awkward fall can all put stress on the MCL, leading to injury.
- Motor vehicle accidents: A car crash or other accident that causes a direct impact to the knee can also result in an MCL injury.
- Twisting/pivoting motions: Sometimes, an MCL injury can occur during activities that involve twisting or pivoting movements, especially when the foot is planted on the ground and the knee is forced to rotate. Non-contact MCL injuries are often associated with other, accompanying injuries in the knee.
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Symptoms of MCL Injuries
The symptoms of an MCL injury of the knee depend on the severity of the ligament tear or knee sprain. Common signs and symptoms include:
Pain on the inner side of the knee:
This is often the first indication of an MCL injury. The pain can range from mild to severe and may worsen with movement or pressure on the knee.
Swelling:
Swelling around the knee joint is typical, especially in more severe injuries. In mild cases, swelling may be minimal and only noticeable after activity.
Instability:
If the ligament is severely damaged, the knee may feel unstable or “wobbly.” You might have difficulty putting weight on the affected leg or may experience a feeling that the knee is going to give out.
Limited range of motion:
The knee may become stiff, and it may be difficult to fully extend or bend the knee without discomfort.
Diagnosis of MCL Injuries
If you suspect that you have an injury to your knee, one of our PhysioTec physios will be able to assist you in confirming the diagnosis and organising imaging where necessary. Most isolated MCL injuries can be diagnosed with a clinical examination by a skilled therapist.
In cases where a moderatw to severe injury is present, your healthcare professional may refer you for an MRI to get a detailed view of the soft tissues, including the MCL, to assess the severity of the injury. Imaging is particularly important when it is necessary to rule out other injuries, including:
- ACL tear
- Patella subluxation
- Meniscal tear/injury
- Medial knee cartilage/chondral injury
- Femoral/Tibial fractures
- Distal hamstring (biceps femoris) injury
Treatment Options for MCL Injuries
Non-surgical treatment:
Fortunately, most MCL injuries can be managed with non-surgical treatment, though early detection is of particular importance. Optimal healing is best achieved when appropriate bracing is fitted as soon as practical after the injury.
Bracing:
Ligaments in the knee are capable of healing on their own if the free ends of the injury are protected from excessive stress. Specific knee braces for MCLs, such as a full-leg hinged knee brace can be set up to restrict the knee’s range of motion, while still allowing the patient to continue with some daily activities. These braces require a trained health professional to set up and guide the permitted range of motion in the brace, to assure a level of protection that is appropriate to the grade of the injury.
RICER: Rest, Ice, Compression, Elevation, and Referral (for imaging if required)
Relative rest and modification to activities of daily living are required to allow a ligament to heal. For higher grade injuries, these restrictions to daily activities, gym and sport may extend for up to 6 weeks, depending on injury grade.
Physiotherapy:
While in a Range-Of-Motion brace (ROM brace) to protect your knee, your PhysioTec physio will be able to work with you to maintain your strength and function in your uninjured limb as well as the injured limb within the constraints of the bracing and injury severity.
As you come out of the brace, your physio will work with you to restore your function, strength, proprioception (ability to feel where your knee is in space) and agility, to safely return to activity and sport.
Surgical treatment:
In complex cases, or when concurrent injuries would interfere with the non-surgical management of the MCL, an orthopaedic surgeon may recommend surgical repair of the ligament.
MCL reconstruction:
In this procedure, the torn ligament is replaced or repaired using a graft, often from the patient's own tissue or a donor graft.
Rehabilitation:
Following surgical repair of an MCL injur of the knee, careful rehabilitation will be performed under the guidance of your treating surgeon and an experienced physiotherapist.
It is recommended that athletes only return to sport once they have clearance from their surgeon and have demonstrated readiness to return to sport through strength, power and control testing by their physiotherapist.
Prevention of MCL Injuries
While it's impossible to eliminate the risk of MCL injuries entirely, certain precautions can help reduce the likelihood of sustaining one, or another one:
- Strength/Power/Proprioception: Keeping up a regular gym or strengthening program when playing sport is always a good idea in optimising resilience of your musculoskeletal tissues. Ensuring you complete your rehabilitation from an MCL injury prior to returning to sport can reduce the dynamic stress on the MCL and reduce the likelihood of injury recurrence, as well as reducing risk of other, subsequent injuries. This involves a battery of testing by your PhysioTec physiotherapist to ensure complete recovery of strength, power and control before return to play.
- Strapping/Bracing: Many athletes choose to have their knee strapped or braced while participating in sport for some time following their injury. This may be indicated as the healing tissue continues to develop strength in the months following injury.
MCL injuries can be a painful and often daunting injury, but the recovery doesn’t need to be. With early detection, the correct management and proper rehabilitation, you can recover from an MCL injury quickly and safely, without the need for invasive surgery.
If you have hurt your knee and are concerned that you may have injured your MCL, don’t hesitate to book an assessment to get a clear understanding of the issue and develop a plan of management for optimal healing and a safe and fast return to activity or sport.
Struggling with a recent knee injury? Visit us at PhysioTec. Our skilled Sports Physio Team, can evaluate your injury and develop a personalised plan to enhance your recovery, helping you get back to doing the activities you love!
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Author
This blog was written by Andrew Vetter, one of our sports physiotherapists. Andrew has a special interest in treating hip, knee, ankle and shoulder injuries and has had much experience with rehabilitation after joint injury including dislocation and reconstructive surgery, during many years working with elite football athletes, including the Qld Reds. Andrew aims to provide high quality care to his patients, help them perform better, recover from injuries, and get back to doing the things they love.
You can read more about Andrew here.
References:
- Vosoughi F, Rezaei Dogahe R, Nuri A, Ayati Firoozabadi M, Mortazavi J. Medial Collateral Ligament Injury of the Knee: A Review on Current Concept and Management. Arch Bone Jt Surg. 2021 May;9(3):255-262. doi: 10.22038/abjs.2021.48458.2401. PMID: 34239952; PMCID: PMC8221433.
- Hunter DJ, MacGregor K, Shields R, Black AM, Rezansoff A, Mohtadi NG. Randomized Clinical Feasibility Trial: Comparing a Restrictive and Protective Range-of-Motion Brace for the Nonsurgical Management of the Medial Collateral Ligament of the Knee. Clin J Sport Med. 2025 Apr 22. doi: 10.1097/JSM.0000000000001361. PMID: 40278544.
- Hunter CDR, Featherall J, McNamara N, Greis PE, Maak TG, Aoki SK, Klasan A, Ernat JJ. Investigating the Ligament Involvement in High-Energy and Polytraumatic Multiligament Knee Injuries Compared With Low-Energy or Isolated Injuries. Orthop J Sports Med. 2025 Feb 6;13(2):23259671241312251. doi: 10.1177/23259671241312251. PMID: 39949631; PMCID: PMC11822837.