Knee Ligament Sprains: Causes, Symptoms, and How We Can Help
- staystrongtherapy
- Jun 30
- 6 min read
All information in this blog is supported by peer-reviewed research and clinical practice guidelines. There is currently no dedicated NICE guideline for this condition, so current evidence is used throughout. Reference numbers appear throughout, with the full list at the bottom of the page.
What Is a Knee Ligament Sprain?
Knee ligaments are strong bands of connective tissue linking the thigh bone to the shin bone and fibula, acting like stabilising cables that control knee movement, support load, and protect the joint from unwanted motion. ¹ There are four primary ligaments, each resisting a different type of force, and a sprain occurs when one of these ligaments is stretched or torn beyond its normal capacity.
Without proper ligament function, basic tasks like walking, pivoting, or squatting can become risky or painful, and long-term instability places additional strain on the cartilage and menisci, increasing the risk of early-onset osteoarthritis if not properly managed. ¹
The Four Main Ligaments and How They're Typically Injured
Anterior cruciate ligament (ACL): prevents the shin bone from sliding too far forward relative to the thigh bone, and is commonly injured during sudden deceleration, pivoting, or landing awkwardly from a jump. ACL injuries can genuinely be a persistently difficult diagnosis in practice, reflecting how varied the presentation can be. ²
Posterior cruciate ligament (PCL): resists backward movement of the shin bone, often injured through direct trauma to the front of the shin, such as in a fall or road traffic accident.
Medial collateral ligament (MCL): runs along the inner side of the knee and resists valgus force (the knee buckling inward), typically injured through a direct blow to the outer knee or a twisting mechanism. Collateral ligament injuries typically occur after valgus or varus force, with physical examination findings including laxity or pain when this stress is applied. ³
Lateral collateral ligament (LCL): runs along the outer side of the knee and resists varus force (the knee buckling outward), considerably less common than MCL injuries.
It's genuinely important to know that concurrent meniscus or cruciate ligament injury is common alongside a collateral ligament sprain and should always be evaluated as part of a thorough assessment. ³ Research has found that ACL injuries are combined with damage to the medial side of the knee, including the MCL, in up to 35% of cases. ⁴
How Severe Is It? Understanding the Grading System
Ligament sprains are classified using a standard grading system: ¹
Grade I (mild): microscopic damage, the ligament remains intact
Grade II (moderate): a partial tear with some instability, healing may take longer
Grade III (severe, complete rupture): often requires surgical intervention, particularly for active individuals
Understanding the grade matters genuinely for setting realistic expectations. Some Grade II injuries can be managed conservatively but require close monitoring for functional improvement, while Grade III injuries, especially in high-demand individuals, often require surgery to restore joint stability. ¹
Common Signs and Symptoms
Pain at the time of injury, often with a specific mechanism such as pivoting, a direct blow, or landing awkwardly
Swelling, sometimes developing rapidly
A feeling of instability or the knee "giving way"
Reduced range of movement
Point tenderness over the affected ligament
A popping sensation at the moment of injury, sometimes reported with ACL tears specifically
What to Look Out For
Please seek medical assessment if you experience:
Inability to bear weight following injury
A visible deformity of the knee
Significant, rapid swelling
A sensation of the knee giving way or locking
Numbness or circulation changes in the lower leg
X-ray may be considered first to rule out a fracture, with MRI being the imaging of choice to confirm and grade ligament injuries where needed. ³
Myths vs Facts
"I need to rest completely and avoid weight-bearing." Bed rest and prolonged immobilisation are not recommended for most ligament sprains. ³ For Grade I and II injuries specifically, research has found no real difference in outcomes when immediate weight-bearing and ambulation were tolerated, alongside appropriate rehabilitation. ⁵
"All ligament sprains need surgery." Not at all. Many sprains, particularly Grade I and II injuries, respond well to conservative physiotherapy-based treatment. Surgery is generally reserved for Grade III ruptures, particularly in more active individuals.
"The treatment approach for MCL injuries is well established." Honestly, less so than you might expect. A recent systematic review of MCL rehabilitation found substantial heterogeneity and a genuine lack of detail regarding non-operative treatment protocols in the published research, including inconsistent use of bracing and poorly reported exercise details. ⁵ This means treatment for MCL injuries specifically is guided as much by individual clinical judgement as by a single, agreed protocol.
How We Can Help
Conservative, physiotherapy-led treatment is the recommended approach for Grade I and II ligament sprains, and remains an important part of recovery alongside surgery for Grade III injuries. ⁵
Osteopathic manual techniques and manual therapy: supporting joint mobility, addressing compensatory tension, and aiding overall recovery once the acute phase has settled.
Deep tissue and sports massage: targeted soft tissue work for the surrounding muscles, supporting circulation and reducing compensatory tension during rehabilitation.
Medical acupuncture and cupping: used as part of a broader treatment plan to support pain management.
Early mobilisation guidance: in line with current evidence, advice on appropriate, early weight-bearing and movement rather than prolonged rest, alongside protective bracing where appropriate.
Exercise and Rehabilitation
Rehabilitation differs depending on the ligament involved and the grade of injury, but several principles are consistently supported by current evidence.
Early, guided weight-bearing: for Grade I and II injuries particularly, immediate weight-bearing and ambulation are generally tolerated and supported, rather than prolonged immobilisation. ⁵
Progressive strengthening exercises: building strength around the knee to restore stability and support the healing ligament, though research notes that exercise protocols across studies are often inconsistently detailed, meaning your programme should be genuinely individualised. ⁵
Quadriceps activation work: particularly relevant following ACL injury, where research has found measurable differences in quadriceps activation between the injured and uninjured side. ⁶
Performance-based testing before return to sport: rather than relying on a fixed timeframe alone, with ongoing research aiming to establish a clearer battery of tests to assess true readiness. ⁶
Graded return to activity: a structured, criteria-based progression, particularly important given the relationship between ligament instability and long-term joint health.
Your practitioner will guide a programme tailored to the specific ligament involved and the grade of your injury.
What to Expect at Your First Appointment
We will take a thorough history, including the mechanism of injury, and carry out a hands-on assessment to identify which ligament or ligaments are involved and the likely grade of injury, including checking for any associated meniscus or other ligament involvement. We will explain clearly what we find and build a progressive, evidence-based rehabilitation plan, referring on for imaging or surgical assessment where appropriate.
Frequently Asked Questions
Do I need an MRI? Not always for milder sprains, but MRI is the imaging of choice to confirm and grade more significant ligament injuries, particularly where surgery may be considered.
Will I need surgery? This depends on the grade and which ligament is involved. Grade III ruptures, particularly of the ACL in active individuals, more often require surgical reconstruction, while many Grade I and II sprains respond well to conservative rehabilitation.
How long will it take to recover? This varies significantly by grade and ligament, mild sprains may improve within a few weeks, while more significant injuries, particularly those requiring surgery, involve a considerably longer, structured rehabilitation process.
Can I keep weight-bearing on it? For most Grade I and II sprains, yes, with guidance. Current evidence does not support prolonged rest or immobilisation, early, appropriate movement generally supports better recovery.
Recognise these symptoms? Get in touch using the contact form and we will assess and build the right treatment plan for you.
References
Knee Ligament Injuries: ACL, PCL, MCL & LCL Explained. Available at: https://drjnegus.com/knee-conditions/ligament-injuries/
Parwaiz H, Teo AQ, Servant C. Anterior cruciate ligament injury: A persistently difficult diagnosis. The Knee. 2015. Referenced via: https://emedicine.medscape.com/article/826792-guidelines
Knee Injury Treatment Guideline. Massachusetts Government Workers' Compensation Guidelines. March 2024. Available at: https://www.mass.gov/doc/knee-injury-treatment-guideline-march-2024/download
Ultrasound-based evaluation revealed reliable postoperative knee stability after combined acute ACL and MCL injuries. PMC. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8443730/
Shedding light on the non-operative treatment of the forgotten side of the knee: rehabilitation of medial collateral ligament injuries, a systematic review. PMC. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11202733/
Knee Ligament Sprain Revision 2017. Orthopaedic Section of the American Physical Therapy Association, Clinical Practice Guideline. Available at: https://www.orthopt.org/uploads/content_files/files/Knee%20Ligament%20Sprain%20CPG%20-%202017.pdf
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