Medial ligament injury (MCL)

Anatomy and function of the medial ligament (MCL)

The medial collateral ligament (MCL) runs on the inside of the knee from the thigh bone (femur) to the shinbone (tibia). It stabilizes the knee against lateral (valgic) forces and works together with the posterior oblique ligament and capsular structures on the medial side. It also cooperates functionally with the meniscus, cruciate ligaments and the muscles (especially adductors, semimembranosus).

The MCL is extra-articular, well supplied with blood and generally has a high healing potential. Injuries often affect the medial crura or near the insertion of the tibia; more rarely, it tears near the femur or as a bony avulsion.

• Primary task: Protection against valgus stress (knee bends inwards).
• Secondary task: co-stabilization against rotational forces.
• Good blood circulation: promotes conservative healing.

Causes and risk factors

Inner ligament injuries usually arise from external force on the outside of the knee (e.g. tackling), from twisted landings or when skiing when the ski remains twisted. In everyday life, falls or missteps can trigger similar mechanisms.

• Contact sports: football, handball, rugby.
• Ski and board sports: twisted landing, binding does not release.
• Malalignment/overload: severe knock knees (genu valgum), muscular imbalances.
• Previous knee injuries, inadequate trunk and hip stability.
• Inappropriate footwear/material, lack of warm-up.

Typical symptoms

The symptoms often begin acutely with a stabbing pain on the inside of the knee. Depending on the severity, there may be swelling, bruising and stress-related pain. Some sufferers report buckling or unsteadiness when moving sideways.

• Local pressure pain along the inner ligament.
• Swelling, possibly bruising on the inside.
• Feeling of instability during lateral movements/valgus stress.
• Pain when changing direction, going down stairs, bending knees deeply.
• Restriction of movement (especially stretching).

Warning signs that require rapid clarification: blocking knee, pronounced instability even in a stretched position, feelings of numbness, severe pain at rest or visible axial misalignment.

Examination and diagnostics

The clinical examination is crucial: localization of the pressure pain, assessment of the swelling and special stability tests. The valgus stress test at 30° knee flexion tests MCL stability; testing in extension may indicate additional involvement of deeper structures. At the same time, we check cruciate ligaments and menisci, as combined injuries are not uncommon.

• Ultrasound: Depiction of fiber interruptions, edema, hematoma; dynamic stress testing possible.
• X-ray: exclusion of bony avulsions/avulsions; Assessment of growth plates in children.
• MRI: In cases of severe instability, suspected combination injuries (e.g. ACL/meniscus) or failure to heal.

The classification into degrees of severity (I–III) is based on pain, stability and fiber involvement. This helps with therapy planning and prognosis.

Severity levels (grades I–III)

Inner ligament injuries are divided into three grades. The information on healing times is a guideline and will be adjusted individually.

First aid in acute cases

In the first 48-72 hours, the focus is on pain relief and swelling reduction. The PECH scheme is helpful.

• Break: Stop straining, avoid painful movements.
• Ice/cooling: 10–15 minutes, several times a day (note skin protection).
• Compression: Elastic bandage to control swelling.
• Elevation: Above heart level, promotes reflux.

Initially avoid heat, alcohol, intense massage, or strong stretching in the area of ​​pain.

Conservative therapy – standard for MCL injuries

The majority of inner ligament injuries heal reliably with conservative therapy. The aim is to achieve pain-adapted, early mobilization while simultaneously protecting the patient against valgus stress.

• Functional knee splint (hinge splint): Protection against valgus stress, depending on the degree, for 2-6 weeks, often with released, pain-adapted flexion/extension.
• Loading: Early functional, often partial weight-bearing with forearm crutches in the first few days; Increase in pain and stability.
• Physiotherapy: Early active, focus on swelling management, range of motion, quadriceps and isometric hamstring activation, patellar mobility.
• Training: Progressive – hip abductors/gluteal muscles, core stability, leg axis control, proprioception (balance, sensorimotor training).
• Taping: In addition to the splint or in later phases in sports with changes of direction.
• Medication: Short-term pain therapy as needed; Dose NSAIDs carefully and do not use them permanently.

We create an individual rehabilitation plan in Hamburg, tailored to the type of sport, job requirements and accompanying findings.

Rehabilitation: phases and goals

Times are guidelines. Criteria and a medical and physiotherapeutic follow-up are crucial.

Regenerative procedures (e.g. PRP)

Regenerative injection therapies such as platelet-rich plasma (PRP) are being discussed for select MCL injuries. Studies suggest potentially faster relief of symptoms and earlier resilience in partial tears, but the evidence is mixed. A clear indication, information about benefits and limitations as well as integration into a structured rehabilitation program are essential.

• Indication especially for grade II or persistent symptoms under standard therapy.
• Not a replacement for training therapy, but a supplement.
• We discuss opportunities, risks and alternatives individually - without any promise of cure.

When does an operation make sense?

Surgery is rarely required for isolated MCL injuries. It is considered in the case of persistent instability despite consistent conservative therapy, in the case of bony avulsions with dislocation, in the case of pinched ligament ends (“Stener-like” lesion) or in the context of complex combined injuries (e.g. with a cruciate ligament tear).

• Direct suture/reinsertion for fresh avulsions.
• Ligament reconstruction with transplant for chronic instability.
• Postoperatively: splint, gradual increase in load; Rehabilitation usually takes 3-6 months depending on combination injuries.

We make decisions based on clinical findings, imaging, activity goals and individual risk-benefit assessment.

Healing process and prognosis

The overall prognosis is good. Many Grade I injuries allow a return to moderate exercise after 2-3 weeks, and Grade II lesions after 4-6 weeks. For grade III, 8-12 weeks should be allowed until the patient is fully able to play sports. Concomitant injuries, older age, extensive swelling, lack of adherence to the splint/rehab and muscular deficits can prolong the course.

• Return-to-sport criteria: pain-free, full mobility, lateral stability without laxity, functional tests (jumping/strength/agility) almost symmetrical.
• Relapse prevention: targeted hip/torso training and technique training.
• Long-term effects are rare, but chronic instability can impact cartilage/meniscus health – treat early.

Prevention: How to prevent it

• Warm up with activation of gluteal muscles and core.
• Leg axis control: landing technique, do not allow the knee to collapse inwards.
• Strength training: hip abductors, hamstrings, quadriceps balanced.
• Proprioception: balance pad, one-legged stand, change of direction.
• Sport-specific: Check ski bindings, suitable footwear, if necessary preventive splints in contact sports after a previous injury.

Differential diagnoses for pain on the inside of the knee

• Medial meniscus lesion
• Pes anserinus tendinitis/bursitis
• Semimembranosus attachment irritation
• Medial plica syndrome
• Bony avulsion or tibial plateau fracture
• Associated injuries: v. a. anterior cruciate ligament (ACL), medial capsule
• Myofascial pain syndromes

When should I seek medical advice?

Seek medical attention if there is severe swelling, marked instability, pain at rest, a feeling of locking, numbness, or a visible misalignment. Even if there is no improvement after 7-10 days despite rest, an examination makes sense. In Hamburg we are happy to be there for you – with structured diagnostics and an individual, conservative treatment plan.