Midfoot arthritis is characterized by the degeneration of cartilage in the middle section of the foot, leading to pain, stiffness, and inflammation. This progressive breakdown of the smooth, protective tissue causes bone-on-bone friction, significantly impairing a person’s ability to walk and stand comfortably. Factors contributing to this chronic problem range from simple wear and tear to severe injury and systemic disease.
Anatomy of the Midfoot Joints
The midfoot acts as the bridge between the ankle and the toes, playing a fundamental role in maintaining the arch and absorbing shock during movement. The joints most frequently affected by arthritis are the tarsometatarsal joints, collectively known as the Lisfranc joints. These joints connect the tarsal bones, which form the arch, to the metatarsal bones.
The midfoot is designed for inherent stability, provided by its unique “Roman arch” configuration. This rigid structure is essential for transforming the foot from a flexible shock absorber into a rigid lever for push-off during walking. The limited movement in these joints means they are highly susceptible to damage from repetitive loading or traumatic events.
Primary Degenerative Causes
The most common form of midfoot joint deterioration is primary osteoarthritis, often referred to as “wear-and-tear” arthritis. This condition typically develops spontaneously over many years without a specific, identifiable injury or underlying disease. It is a slow, age-related process where the articular cartilage gradually thins due to decades of repetitive stress from walking and standing.
As the cartilage erodes, the underlying bone reacts by thickening and attempting to repair the damage. This process leads to the formation of osteophytes, or bone spurs, around the joint margins. These spurs cause pain by rubbing against adjacent bones or pressing on surrounding soft tissues. The second and third tarsometatarsal joints, which bear the majority of the force during gait, are often the first to show signs of this gradual degeneration.
Post-Traumatic Origins
Post-traumatic arthritis is arguably the most common cause of midfoot arthritis, arising from a previous injury that permanently altered the joint mechanics. The trauma may have been a high-energy event, such as a motor vehicle accident, or a seemingly minor injury, like a severe twist or sprain. Even when an injury is treated expertly, the initial damage to the cartilage or the stabilizing ligaments can accelerate the degenerative process years later.
Lisfranc injuries, which involve a fracture or dislocation of the tarsometatarsal joint complex, are particularly notorious for leading to post-traumatic arthritis. Damage to the strong Lisfranc ligament destabilizes the entire midfoot arch. This instability causes the bones to move abnormally, leading to concentrated areas of pressure and accelerated wear on the joint surfaces. Up to 50% of people who experience a Lisfranc injury may develop chronic midfoot pain and arthritis due to this irreparable damage.
Systemic and Inflammatory Disorders
Midfoot arthritis can also be a manifestation of a systemic inflammatory disorder that affects joints throughout the body. These conditions cause chronic inflammation that attacks the joint structures from within. Rheumatoid Arthritis (RA) is a well-known example where the body’s immune system mistakenly attacks the synovium, the lining of the joints, leading to cartilage and bone destruction.
Other inflammatory types include Psoriatic Arthritis, associated with the skin condition psoriasis, and Gout, caused by the buildup of uric acid crystals in the joint space. These crystals trigger an intense inflammatory response, leading to rapid and painful joint damage. Unlike degenerative arthritis, inflammatory arthritis tends to cause a more symmetric pattern of joint destruction across the midfoot.
Contributing Biomechanical Factors
The structure of the foot and the distribution of body weight significantly influence the likelihood of developing midfoot arthritis. Foot structure abnormalities, such as a severe flat foot (pes planus) or a high arch (pes cavus), alter the alignment of the midfoot joints. This misalignment causes uneven loading, concentrating excessive force on specific joint surfaces and accelerating the wear-and-tear process.
Excessive body weight dramatically increases the load placed on the relatively small joints of the midfoot during daily activities. The increased compressive forces on the tarsometatarsal joints hasten the breakdown of articular cartilage, speeding up the onset of degenerative changes. Similarly, repetitive, high-impact activities, such as long-distance running or certain jumping sports, impose intense and frequent stresses on the midfoot structure, making the individual susceptible to early-onset arthritis.