Posterior tibial tendonitis, also known as posterior tibial tendon dysfunction (PTTD), is a common and often debilitating condition affecting the foot and ankle. It involves inflammation or degeneration of the posterior tibial tendon, which can lead to discomfort and impaired mobility. Understanding the specific factors that contribute to its development is important for both prevention and effective management.
Understanding the Posterior Tibial Tendon
The posterior tibial tendon originates from a muscle in the calf, specifically from the posterior surface of the tibia and fibula bones. It descends along the back of the lower leg, wrapping around the inside of the ankle bone (medial malleolus) before attaching to various bones on the inner side of the foot, primarily the navicular bone.
The primary function of this tendon is to support the arch of the foot and help with ankle inversion (turning the sole of the foot inward). It also plays a role in plantarflexion (pointing the foot downward). The posterior tibial tendon acts as a crucial stabilizer for the medial arch, helping to maintain foot structure and facilitate normal walking and weight-bearing activities.
Direct Causes of Tendonitis
Posterior tibial tendonitis frequently arises from repetitive strain. Activities such as running, jumping, prolonged walking, or high-impact sports like basketball and tennis can gradually overload the tendon. This sustained pressure can lead to microscopic tears within the tendon fibers, initiating an inflammatory response as the body attempts to repair the damage.
Acute injury or trauma to the foot and ankle is another direct cause. A sudden incident, such as a fall or a forceful twisting of the ankle, can directly damage or even tear the posterior tibial tendon.
A rapid increase in physical activity without adequate conditioning can also trigger posterior tibial tendonitis. Escalating intensity, duration, or frequency too quickly can overwhelm the tendon, making it more susceptible to injury and inflammation.
Factors Increasing Risk
Certain pre-existing foot structures, such as flat feet or pes planus, significantly increase the risk of developing posterior tibial tendonitis. When the arch of the foot is flattened, the posterior tibial tendon must work harder to support it. This increased workload places greater strain on the tendon, making it vulnerable to inflammation and damage.
Age is another contributing factor, as tendons can lose elasticity and strength over time. Posterior tibial tendonitis is more commonly observed in individuals over 40.
Excess body weight increases the load on the foot and ankle structures, including the posterior tibial tendon. This added stress can lead to increased strain and an increased risk of tendon issues.
Certain medical conditions can increase susceptibility to tendonitis. Conditions like diabetes and inflammatory arthritis may weaken tendons or impair their healing. Improper footwear, such as those lacking adequate arch support, can contribute to increased strain on the posterior tibial tendon.
How the Condition Progresses
If left unaddressed, the condition can progress. Initial inflammation can lead to tendon degeneration, where the tendon tissue breaks down. This weakening impairs the tendon’s ability to support the arch of the foot.
As the tendon weakens, the arch of the foot can gradually collapse, leading to adult-acquired flatfoot deformity. This can cause the ankle to roll inward and the toes to turn outward, altering foot alignment. Pain often increases and may shift to the outside of the ankle as the foot flattens further.
In advanced stages, ongoing stress and misalignment can lead to the development of arthritis in the foot and ankle joints. In severe instances, the weakened tendon may even experience a complete rupture.