Flat feet, a condition where foot arches are diminished or absent, can contribute to knee pain. This occurs by influencing lower limb mechanics and leading to discomfort higher up the kinetic chain.
What Are Flat Feet
Flat feet (pes planus) occur when the arch on the inner sole flattens and appears to touch the ground when standing, often due to weakened or misaligned bones and connective tissues. There are two types: flexible and rigid flat feet.
Flexible flat feet are the most common type; an arch is visible when not bearing weight but flattens when standing. This type often develops in childhood and may or may not cause symptoms. In contrast, rigid flat feet have no arch present regardless of weight bearing and can make flexing difficult. This less common type often results from structural issues like bone irregularities or arthritis. While approximately 20-30% of the population has flat feet, not everyone experiences pain.
How Flat Feet Affect Knee Mechanics
Flat feet contribute to knee pain primarily through excessive pronation. Pronation is the foot’s natural inward roll during walking or running, absorbing shock. With flat feet, this roll exaggerates, causing a chain reaction up the leg.
Excessive pronation internally rotates the tibia (shin bone) and femur (thigh bone). This misalignment stresses knee joint structures. The patella (kneecap) may track improperly, causing friction and irritation behind it. This can lead to conditions like patellofemoral pain syndrome, often called “runner’s knee,” characterized by pain around or behind the kneecap, especially with activities like squatting or climbing stairs. The increased rotational forces can also stress ligaments, such as the medial collateral ligament (MCL), and contribute to conditions like iliotibial band (IT band) syndrome, which causes pain on the outside of the knee.
Managing Knee Pain Linked to Flat Feet
Knee pain linked to flat feet often presents as aching around or behind the kneecap, or on the inner side of the knee. This pain may worsen with activities like running, climbing stairs, or prolonged standing, and sometimes includes swelling or clicking sounds. A healthcare professional typically diagnoses the connection through physical examination, gait analysis, and sometimes imaging if other issues are suspected.
Management strategies aim to support the foot and improve lower limb alignment. Supportive footwear with good arch support and stability is often recommended. Orthotics, either over-the-counter or custom-made inserts, can provide arch support and help control excessive pronation. Physical therapy strengthens intrinsic foot muscles, improves hip and core stability, and stretches tight muscles like the calves.
For acute pain, conservative measures such as the RICE method (Rest, Ice, Compression, Elevation) can help reduce swelling and discomfort. Rest involves avoiding activities that aggravate the pain, while ice applied for 10-20 minutes several times a day can minimize swelling. Compression with an elastic bandage helps limit fluid buildup, and elevating the leg above heart level can further reduce swelling. Maintaining a healthy weight and modifying high-impact activities can also alleviate stress on the knees. If pain persists, worsens, or becomes severe, consulting a doctor, podiatrist, or physical therapist is advisable for a comprehensive evaluation and tailored treatment plan.