Midfoot arthritis is a condition where the cartilage in the middle section of the foot joints wears down. This area includes the tarsometatarsal and cuneiform joints, which connect the rearfoot to the forefoot. The midfoot structure provides stability and absorbs shock with every step. When the cartilage degenerates, it impairs the foot’s ability to distribute weight properly, leading to pain and stiffness. Understanding the causes of this damage is the first step toward managing this condition.
Primary Degenerative Changes
The most common form of joint damage is primary osteoarthritis (OA), often called “wear and tear” arthritis. This condition develops over many years as the smooth, protective layer of articular cartilage covering the bone ends slowly breaks down. Over time, the chronic stresses of walking and standing diminish the cartilage’s ability to cushion the bones, leading to thinning and fragmentation.
The progressive loss of this cushioning causes the joint space to narrow, resulting in friction between the bones. This bone-on-bone rubbing triggers the body to form new bone growth at the edges of the joint, known as bone spurs or osteophytes. These bony outgrowths can cause a noticeable lump on the top of the foot and further restrict motion in the midfoot joints. This age-related degeneration results from years of mechanical stress, often occurring even without a major injury.
Post-Traumatic Arthritis
Post-traumatic arthritis is a common cause of midfoot degeneration, often surpassing primary osteoarthritis in prevalence for this area. This type of arthritis develops following a significant injury that damages the joint surfaces, including fractures, dislocations, or severe sprains. The midfoot is vulnerable to this, especially in high-impact scenarios.
The most notorious injury in this region is the Lisfranc injury, which involves the tarsometatarsal joint complex. Even after successful surgical repair, damage to the cartilage and supporting ligaments can lead to joint incongruity, meaning the joint surfaces no longer align smoothly. This misalignment creates abnormal stress points and accelerates cartilage wear, causing premature arthritis years after the initial event. Up to 50% of people who suffer a Lisfranc injury may develop post-traumatic arthritis.
Systemic Inflammatory Triggers
Midfoot arthritis can be a manifestation of diseases that affect the entire body, known as systemic inflammation. These conditions involve the immune system mistakenly attacking healthy tissues, including the joints. The foot is a common target for these systemic processes.
Rheumatoid Arthritis (RA) is a major culprit, where the immune system attacks the synovium, the thin lining that lubricates the joint. This attack causes prolonged inflammation, which ultimately leads to the erosion of articular cartilage and underlying bone. Crystal Deposition Diseases, such as Gout, result from elevated levels of uric acid in the blood. When uric acid levels are too high, they form sharp crystals that deposit in the joint, causing acute inflammatory episodes that damage the joint structures.
Contributing Biomechanical Factors
Existing structural issues and lifestyle choices can accelerate the degenerative processes in the midfoot joints. Biomechanical factors like abnormal foot alignment directly influence how forces are distributed across the foot during movement. For instance, a collapsed arch (flat feet or pes planus) or a high arch (pes cavus) can lead to uneven pressure distribution.
Excessive body weight (obesity) places a greater load on the midfoot joints with every step, compounding the effect of poor alignment. Studies show that obese individuals exhibit greater compression of the medial longitudinal arch, increasing pressure on the midfoot area. This constant, excessive load accelerates the rate of cartilage breakdown, speeding up the onset of osteoarthritis. Repetitive high-impact activities similarly contribute to accelerated wear by subjecting the joints to greater forces.
Midfoot arthritis rarely results from a single event, but rather from a convergence of factors including age-related changes, past injuries, systemic diseases, and the effects of foot mechanics and body weight. The complexity of this diagnosis arises from the interwoven nature of these causes, which contribute to the breakdown of the foot’s support structures.