Flat Feet

• The most common form is flexible pes planus, where the arch appears when the foot is off the ground or when rising onto the toes but collapses during weight-bearing. This type often begins in childhood due to ligament laxity and may persist into adulthood. Symptoms vary from none at all to fatigue, discomfort, or overpronation, but the foot remains mobile and responds well to conservative care.
• Rigid pes planus is less common and more serious. In this type, the arch is absent in all positions, including sitting or standing on the toes. It is associated with stiffness, pain, and limited motion. Because the deformity is fixed rather than flexible, this form often requires more extensive evaluation and more advanced treatment.
• Congenital pes planus is present at birth and usually flexible, though severe deformities produce a rigid, fixed flat foot that requires early correction. Pediatric flexible flatfoot is common in young children and often improves naturally as the ligaments strengthen with age.
• Adult-acquired flatfoot deformity (AAFD) develops later in life, most often from posterior tibial tendon dysfunction. As this tendon weakens, the arch collapses, the heel drifts outward, and pain progresses along the inner ankle. Without appropriate care, the deformity can advance and lead to arthritis.
• Other forms include neuromuscular pes planus, caused by conditions that weaken foot-supporting muscles, and traumatic pes planus, which follows fractures or ligament injuries that disrupt the arch structure.

These categories help determine severity, progression, and the most effective treatment plan for each patient.

Symptoms of flat feet can vary widely, depending on the severity of the arch collapse and whether the condition is flexible or rigid.

• Fatigue or aching along the arch or heel after prolonged standing or walking.
• Pain on the inner ankle.
• Swelling around the inside of the foot or ankle, especially after physical activity.
• Stiffness and limited mobility, making it difficult to rise onto the toes or participate in sports.
• Flat feet can also alter gait patterns, causing a tendency for the feet to roll inward excessively (overpronation). This additional strain contributes to pain higher up the kinetic chain, including shin splints, knee discomfort, hip tightness, and lower-back pain. Over time the condition can lead to progressive deformities, including bunions, hammertoes, and chronic tendon dysfunction.

• In children, flat feet are often the result of loose ligaments and flexible joints. Most children develop normal arches as they grow, but for some, the arch never fully forms.
• In adults, the condition commonly arises from posterior tibial tendon dysfunction (PTTD), a gradual weakening or tearing of the tendon that stabilizes the arch. Trauma, such as fractures or dislocations, can also damage the bones or ligaments and lead to arch collapse.
• Additional risk factors include obesity, diabetes, inflammatory arthritis, and conditions that affect nerve or muscle function.
• Pregnancy may temporarily flatten the arches due to hormonal changes that increase ligament laxity.
• Aging naturally weakens the supporting tissues of the foot, making adult-acquired flatfoot more common in middle age and beyond.
• Genetics also play a role; having family members with flat feet increases the likelihood of developing the condition.

Diagnosing pes planus starts with a comprehensive evaluation that examines both the structure and function of the foot. The orthopedic specialists at Orthopedic Associates of Northern California assess the patient’s medical history, symptoms, and activity level to understand when and how pain develops.

A physical examination evaluates arch height, alignment, flexibility, and gait mechanics. The provider will often ask the patient to stand, walk, and rise onto their toes while observing foot posture and ankle stability. This helps distinguish between flexible flat feet—where the arch appears when the patient is sitting or tiptoeing—and rigid flat feet, where the arch remains absent in all positions. Palpation along the tendons and ligaments helps identify areas of inflammation or weakness, especially the posterior tibial tendon.

Imaging studies play an important role in confirming the diagnosis and identifying underlying structural problems. Weight-bearing X-rays allow the physician to evaluate bone alignment, joint spacing, and any deformity that occurs under load. In cases where tendon damage is suspected, ultrasound or MRI may be used to assess the integrity of the soft tissues.

Flat feet are manageable when diagnosed early, but ignoring symptoms can allow the condition to worsen over time. A focused evaluation helps determine the appropriate treatment strategy and reduces the risk of long-term complications. Orthopedic Associates of Northern California provides individualized care for patients with flat feet, helping them stay active, mobile, and comfortable with forward-looking treatment approaches tailored to the severity of the condition.