Medial Knee Pain: Causes, Symptoms, and Management When Bending

Why does the medial side of my knee hurt when I bend?

Medial knee pain during bending often indicates stress or injury to structures on the inside of the knee, such as the medial collateral ligament (MCL), medial meniscus, or the pes anserine bursa/tendons, with the bending motion placing specific loads on these tissues.

Understanding Medial Knee Pain

Pain on the medial (inner) side of the knee, particularly when bending or flexing the joint, is a common complaint that can arise from a variety of sources. The knee is a complex hinge joint, and its medial aspect is crucial for stability and proper function. When you bend your knee, the joint undergoes significant biomechanical changes, including compression, tension, and shear forces, which can exacerbate underlying issues in the medial compartment.

Key Anatomical Structures Involved

To understand why pain occurs, it's essential to identify the key structures located on the medial side of the knee:

• Medial Collateral Ligament (MCL): A strong band of connective tissue running along the inside of the knee, connecting the femur (thigh bone) to the tibia (shin bone). Its primary role is to resist valgus stress (forces that push the knee inward).
• Medial Meniscus: A C-shaped piece of cartilage that acts as a shock absorber and helps distribute weight evenly across the joint. It sits between the femur and tibia on the medial side.
• Pes Anserine: The collective insertion point of three hamstring muscles (sartorius, gracilis, and semitendinosus) onto the medial aspect of the tibia, just below the knee joint line.
• Pes Anserine Bursa: A small fluid-filled sac located beneath the pes anserine tendons, designed to reduce friction.
• Articular Cartilage: The smooth, slippery tissue covering the ends of the femur and tibia, allowing for frictionless movement.
• Medial Patellofemoral Ligament (MPFL): A ligament connecting the kneecap (patella) to the medial side of the femur, crucial for patellar stability.
• Adductor Muscles: Muscles on the inner thigh that contribute to hip adduction but also influence knee mechanics.

Common Causes of Medial Knee Pain During Bending

Pain during knee flexion can stem from several conditions affecting these structures:

• Medial Collateral Ligament (MCL) Sprain/Strain:
  • Mechanism: Often caused by a direct blow to the outside of the knee (valgus stress) or a sudden twisting motion.
  • Symptoms: Pain and tenderness along the inner knee, especially when the knee is bent and twisted, or when pressure is applied to the medial side. Swelling may be present. Bending can stretch the injured ligament, causing pain.
• Medial Meniscus Tear:
  • Mechanism: Can occur acutely from a twisting injury with the foot planted, or degeneratively over time due to wear and tear.
  • Symptoms: Sharp pain, especially with twisting, squatting, or deep knee bending. May include clicking, popping, or a sensation of the knee "catching" or "locking." Bending places compressive and shear forces on the meniscus.
• Pes Anserine Bursitis/Tendinopathy:
  • Mechanism: Inflammation of the pes anserine bursa or irritation/degeneration of the pes anserine tendons. Often an overuse injury, common in runners, swimmers, and those with tight hamstrings or weak quadriceps.
  • Symptoms: Pain and tenderness about 2-3 inches below the joint line on the inner side of the knee. Pain typically worsens with bending, climbing stairs, or getting up from a chair.
• Medial Compartment Osteoarthritis (OA):
  • Mechanism: Degeneration of the articular cartilage on the inner side of the knee joint. Common with aging, previous injury, or excessive load.
  • Symptoms: Aching pain that worsens with activity, particularly weight-bearing movements like bending, squatting, or climbing stairs. Stiffness, especially after rest. May feel grinding or crepitus.
• Patellofemoral Pain Syndrome (PFPS) with Medial Stress:
  • Mechanism: While PFPS typically causes pain around or behind the kneecap, imbalances in patellar tracking can lead to excessive stress on the medial facet of the patella or medial retinaculum.
  • Symptoms: Diffuse pain around the kneecap, which can manifest medially, especially with bending activities like squatting, lunging, or prolonged sitting with bent knees.
• Medial Plica Syndrome:
  • Mechanism: The plica are normal folds in the synovial lining of the knee joint. If a medial plica becomes irritated or inflamed (e.g., from overuse or direct trauma), it can become thickened and catch between the femur and patella.
  • Symptoms: Aching pain on the medial side of the kneecap, sometimes with a snapping or clicking sensation, particularly when bending the knee.
• Referred Pain:
  • Mechanism: Less common, but pain originating from the hip or lumbar spine can sometimes be referred to the medial knee.

Why Does Bending Exacerbate the Pain?

Knee bending (flexion) places specific demands on the medial knee structures:

• Increased Compression: As the knee bends, especially during weight-bearing activities like squatting, the medial compartment of the joint experiences significant compressive forces. This can aggravate conditions like medial meniscus tears or osteoarthritis.
• Stretching and Tension: Deep knee flexion can put tension on ligaments (like the MCL) and tendons (like the pes anserine tendons). If these structures are injured or inflamed, this stretching will elicit pain.
• Shear Forces: Twisting motions combined with bending can create shear forces that particularly stress the menisci and ligaments.
• Patellar Tracking: The kneecap moves within a groove on the femur during bending. If there are tracking issues, increased pressure or friction can occur on the medial side of the patella.

When to Seek Professional Help

While some mild knee pain may resolve with rest, it's crucial to consult a healthcare professional (e.g., physician, physical therapist, orthopedist) if you experience:

• Sudden, severe pain or inability to bear weight.
• Significant swelling, redness, or warmth around the knee.
• A "pop" or "snap" at the time of injury.
• Knee "locking," "catching," or "giving way."
• Pain that worsens or doesn't improve with self-care after a few days.
• Numbness or tingling in the leg or foot.

Initial Self-Care Strategies

For mild, acute medial knee pain (and assuming no severe injury), consider these initial steps:

• R.I.C.E. Protocol:
  • Rest: Avoid activities that worsen the pain.
  • Ice: Apply ice packs to the medial knee for 15-20 minutes, several times a day, to reduce pain and swelling.
  • Compression: Use a compression bandage to help reduce swelling.
  • Elevation: Elevate your leg above heart level when resting.
• Activity Modification: Temporarily avoid deep squats, lunges, running, jumping, and activities involving twisting.
• Gentle Range of Motion: Once initial pain subsides, gently move your knee through pain-free ranges of motion to prevent stiffness.
• Over-the-Counter Pain Relievers: Non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen can help manage pain and inflammation.

Prevention and Long-Term Management

Addressing the root causes and preventing recurrence involves a comprehensive approach:

• Strengthening Exercises:
  • Quadriceps: Strengthen the vastus medialis obliquus (VMO) to improve patellar tracking.
  • Hamstrings: Ensure balanced strength with quadriceps.
  • Glutes: Strong gluteal muscles (maximus and medius) are crucial for hip stability, which directly impacts knee alignment and reduces valgus stress.
  • Adductors and Abductors: Maintain balanced strength in the inner and outer thigh muscles to control knee alignment.
• Flexibility and Mobility:
  • Hamstring and Quadriceps Flexibility: Address tightness that can alter knee mechanics.
  • Calf Flexibility: Tight calves can impact ankle and knee alignment.
• Proper Exercise Form: Focus on correct biomechanics during squats, lunges, and other lower body exercises to avoid placing undue stress on the medial knee. Ensure knees track over toes, avoiding excessive valgus collapse (knees caving inward).
• Appropriate Footwear and Orthotics: Worn-out shoes or inadequate arch support can alter foot and ankle mechanics, translating to stress on the knee. Custom or over-the-counter orthotics may be beneficial for individuals with pronation issues.
• Gradual Progression: When starting new activities or increasing intensity, do so gradually to allow tissues to adapt.
• Warm-up and Cool-down: Always include dynamic warm-ups before exercise and static stretches afterward.

Conclusion

Medial knee pain during bending is a signal that one or more structures on the inner side of your knee are being overloaded or injured. While many cases respond to conservative management and activity modification, persistent or severe pain warrants a professional evaluation to obtain an accurate diagnosis and develop an effective treatment plan. By understanding the anatomy, common causes, and proactive strategies, you can better manage and prevent medial knee discomfort, maintaining your joint health and mobility.