The Science of Metatarsalgia

Metatarsalgia represents a symptom complex rather than a specific diagnosis, describing pain under the metatarsal heads in the forefoot. This mechanical overload syndrome occurs when weight-bearing forces exceed the tissues' adaptive capacity, leading to inflammation and pain in the plantar structures of the forefoot. The normal forefoot functions as a complex lever system during push-off, with forces distributed across all five metatarsal heads. The central metatarsals (second and third) typically bear the greatest loads due to their length and position in the transverse arch. When this load distribution becomes pathological, excessive pressure concentrates under one or more metatarsal heads. Several pathophysiological mechanisms contribute to metatarsalgia development. Primary metatarsalgia results from anatomical variants like elongated metatarsals or plantarflexed positioning that increase localized pressure. Secondary metatarsalgia develops from other conditions that alter forefoot mechanics, including hallux valgus, hammer toes, or first ray insufficiency that causes load transfer to the lesser metatarsals. The plantar fat pad plays a crucial role in shock absorption and pressure distribution. With aging, this fat pad undergoes atrophy and displacement, reducing its protective effect. Repetitive loading can accelerate this process, particularly in high-impact activities or when combined with inappropriate footwear. Inflammatory changes occur in response to excessive mechanical stress, affecting the joint capsules, surrounding soft tissues, and skin. Chronic inflammation can lead to synovitis of the metatarsophalangeal joints, plantar plate tears, and development of hyperkeratotic lesions (calluses) that further concentrate pressure points.