Medial Knee Injuries: Understanding MCL, Meniscus Tears, and Pes Anserine Bursitis

What is a Knee Injury on the Inside of the Knee?

Injuries to the inside (medial aspect) of the knee typically involve structures such as the medial collateral ligament (MCL), medial meniscus, and the pes anserine bursa, often resulting from direct impact, twisting forces, or repetitive stress.

Anatomy of the Medial Knee

The knee is a complex hinge joint formed by the articulation of the femur (thigh bone), tibia (shin bone), and patella (kneecap). Understanding the key structures on its medial (inner) side is crucial for comprehending injuries in this area.

• Medial Collateral Ligament (MCL): This strong, flat band of connective tissue runs along the inner side of the knee, connecting the femur to the tibia. Its primary role is to provide stability to the knee joint by preventing excessive valgus stress (forces that push the knee inward, causing the lower leg to move outward relative to the thigh). It also helps resist external rotation of the tibia.
• Medial Meniscus: One of two crescent-shaped pieces of cartilage (menisci) located between the femur and tibia. The medial meniscus acts as a shock absorber, distributes weight evenly across the joint, and contributes to knee stability. It is C-shaped and less mobile than its lateral counterpart, making it more susceptible to injury.
• Pes Anserine Bursa: A small, fluid-filled sac located approximately 2-3 inches below the knee joint line on the inner side of the tibia. It sits beneath the tendons of three muscles—the sartorius, gracilis, and semitendinosus—which collectively form the "pes anserinus" (Latin for "goose's foot" due to their combined appearance). The bursa's function is to reduce friction between these tendons and the bone, facilitating smooth movement.

Common Medial Knee Injuries

Several conditions can cause pain and dysfunction on the inside of the knee. The most prevalent include:

• Medial Collateral Ligament (MCL) Injury

  • Description: An MCL injury involves a stretch, partial tear, or complete rupture of the medial collateral ligament. These injuries are graded based on severity:
    • Grade I: A mild stretch with microscopic tears; stability is maintained.
    • Grade II: A partial tear with some laxity (instability) when tested.
    • Grade III: A complete rupture of the ligament, leading to significant instability.
  • Mechanism: Most commonly occurs from a direct blow to the outside of the knee (valgus stress), forcing the knee inward. This is common in contact sports like football or soccer. It can also result from a non-contact twisting injury.
  • Symptoms: Immediate pain on the inside of the knee, tenderness directly over the MCL, swelling, and a feeling of instability or the knee "giving way," particularly with Grade II or III injuries.

• Medial Meniscus Tear

  • Description: A tear in the C-shaped medial meniscus cartilage. Tears can vary in type (e.g., radial, horizontal, bucket-handle) and size.
  • Mechanism: Often occurs due to forceful twisting or rotation of the knee, especially when the foot is planted and the knee is bent (e.g., deep squatting, changing direction rapidly). Degenerative tears can occur in older individuals with minimal trauma due to wear and tear over time.
  • Symptoms: Pain on the inside of the knee, especially with twisting or squatting movements. Swelling may develop gradually. Mechanical symptoms such as clicking, popping, catching, or locking of the knee are common, where the knee gets stuck in a position.

• Pes Anserine Bursitis

  • Description: Inflammation of the pes anserine bursa.
  • Mechanism: Typically an overuse injury caused by repetitive friction and stress on the bursa. Common contributing factors include tight hamstring muscles, obesity, osteoarthritis of the knee, valgus knee alignment (knock-knees), and improper training techniques (e.g., in runners or cyclists).
  • Symptoms: Gradual onset of pain and tenderness on the inner side of the knee, specifically a few inches below the joint line. The pain often worsens with activity, especially climbing stairs, running, or getting up from a seated position. Unlike MCL injuries, direct trauma is usually not the cause, and mechanical symptoms like locking are absent.

Causes and Risk Factors

Medial knee injuries can arise from various factors, including:

• Acute Trauma:
  • Direct impact: A blow to the outside of the knee (e.g., during sports).
  • Sudden twisting or pivoting: Especially with a planted foot.
  • Hyperflexion or hyperextension: Extreme bending or straightening of the knee.
• Overuse and Repetitive Stress:
  • Repetitive activities like running, cycling, or jumping, particularly on uneven surfaces or with improper form.
  • Sudden increases in training volume or intensity.
• Poor Biomechanics and Muscle Imbalances:
  • Weakness in hip abductor muscles (glutes).
  • Tight hamstrings or quadriceps.
  • Excessive pronation of the feet (flat feet).
  • Valgus knee alignment ("knock-knees").
• Inadequate Warm-up and Cool-down: Muscles and connective tissues are less pliable when not properly prepared for activity.
• Previous Injuries: A history of knee injuries can predispose individuals to future issues.
• Age and Degenerative Changes: As we age, cartilage and ligaments can weaken and become less elastic, increasing susceptibility to tears.

Common Symptoms

While specific symptoms vary by injury type, common indicators of a medial knee injury include:

• Pain: Localized on the inside of the knee, which may worsen with specific movements (twisting, squatting, climbing stairs) or activities.
• Swelling: Can range from mild to significant, depending on the severity and type of injury.
• Tenderness: Pain when pressing directly on the injured area (e.g., over the MCL or pes anserine bursa).
• Stiffness: Difficulty bending or straightening the knee fully.
• Instability: A feeling that the knee is "giving way" or buckling, particularly with MCL injuries.
• Mechanical Symptoms: Clicking, popping, catching, or locking sensations within the joint, common with meniscus tears.
• Reduced Range of Motion: Inability to fully extend or flex the knee.

Diagnosis

Accurate diagnosis is crucial for effective treatment and typically involves:

• Medical History: The healthcare provider will ask about the onset of pain, specific activities that cause or worsen symptoms, and any history of injury.
• Physical Examination: This includes:
  • Palpation: Feeling for tenderness, swelling, and warmth around the medial knee.
  • Range of Motion Assessment: Checking the knee's flexibility and extension.
  • Special Tests: Performing specific maneuvers to evaluate the integrity of ligaments (e.g., valgus stress test for MCL) and menisci (e.g., McMurray's test).
  • Gait Analysis: Observing how the individual walks to identify any biomechanical abnormalities.
• Imaging Studies:
  • X-rays: Primarily used to rule out fractures or identify signs of osteoarthritis.
  • Magnetic Resonance Imaging (MRI): The gold standard for visualizing soft tissue injuries, including ligaments, menisci, tendons, and bursae.

Treatment Principles

Treatment for medial knee injuries varies based on the specific diagnosis and severity. Most mild to moderate injuries are managed conservatively.

• Acute Phase (RICE Protocol):
  • Rest: Avoid activities that aggravate the knee.
  • Ice: Apply ice packs for 15-20 minutes several times a day to reduce pain and swelling.
  • Compression: Use an elastic bandage to minimize swelling.
  • Elevation: Keep the leg elevated above heart level.
• Pain Management: Over-the-counter non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen can help manage pain and inflammation.
• Physical Therapy: A cornerstone of recovery, focusing on:
  • Restoration of Range of Motion: Gentle exercises to regain full knee flexibility.
  • Strengthening Exercises: Targeting quadriceps, hamstrings, glutes, and hip abductors to improve knee stability and support.
  • Proprioception and Balance Training: Exercises to improve the body's awareness of joint position and enhance stability.
  • Gait Training: Correcting walking patterns if needed.
• Bracing or Taping: May be used temporarily to provide support and limit motion during the healing phase, especially for MCL injuries.
• Injections: In some cases of persistent bursitis, corticosteroid injections may be used to reduce inflammation.
• Surgery: Generally reserved for severe cases, such as complete MCL ruptures (rarely needed), complex meniscus tears that cause mechanical symptoms, or when conservative treatment fails to provide relief.

Prevention Strategies

Preventing medial knee injuries involves a holistic approach to fitness and movement mechanics:

• Proper Warm-up and Cool-down: Always perform dynamic warm-ups before exercise and static stretches afterward.
• Strength Training: Develop balanced strength in the muscles surrounding the knee, including quadriceps, hamstrings, glutes, hip abductors, and calves. Focus on compound movements and unilateral exercises.
• Flexibility and Mobility: Regularly stretch tight muscles (e.g., hamstrings, hip flexors, adductors) to improve joint range of motion.
• Appropriate Footwear: Wear supportive shoes suitable for your activity, and consider orthotics if you have significant biomechanical issues like excessive pronation.
• Gradual Progression: Increase the intensity, duration, or frequency of your workouts gradually to allow your body to adapt.
• Maintain a Healthy Weight: Excess body weight places additional stress on the knee joints.
• Correct Biomechanics: Work with a fitness professional or physical therapist to identify and correct any movement imbalances or faulty mechanics during activities.
• Listen to Your Body: Do not push through pain. Rest and seek advice if you experience persistent discomfort.

When to Seek Medical Attention

While minor knee pain can often be managed with rest and ice, it's important to consult a healthcare professional if you experience:

• Severe pain or inability to bear weight on the affected leg.
• Significant swelling or visible deformity around the knee.
• The knee locking, catching, or repeatedly giving way.
• Numbness or tingling in the lower leg or foot.
• Symptoms that worsen or do not improve after a few days of rest and self-care.