Haglund’s deformity is a common foot condition involving an abnormality of the bone and soft tissues at the back of the heel. It is defined by a bony enlargement on the posterior superior aspect of the calcaneus, or heel bone, often referred to as a “pump bump.” This growth frequently irritates the retrocalcaneal bursa near the Achilles tendon, resulting in painful inflammation known as retrocalcaneal bursitis. The development of this heel pain is caused by a complex interaction between a person’s underlying foot structure and external mechanical forces.
Anatomical Predispositions
The foundational cause of Haglund’s deformity lies in the inherited structure of the foot and ankle. The condition begins with a prominent posterosuperior aspect of the calcaneus, the upper, back corner of the heel bone. This natural variation creates a closer proximity between the bone, the overlying Achilles tendon, and the retrocalcaneal bursa. The increased bone projection acts as a fixed point of potential friction and compression against soft tissues and external factors like footwear.
A high-arched foot, scientifically known as pes cavus, is a significant inherited structural element that increases susceptibility. Individuals with this foot type often exhibit an increased calcaneal pitch, describing a more vertical angle of the heel bone. This altered alignment pushes the back of the calcaneus upward and backward, magnifying the prominence. This reduces the space between the heel bone and the Achilles tendon insertion, predisposing the area to friction and irritation.
The body’s response to chronic irritation is the gradual formation of an exostosis, or extra bone growth, on the calcaneus. Bone is a living tissue that attempts to reinforce areas of stress, and constant mechanical irritation stimulates the formation of the distinctive bony bump. This enlargement is a projection on the back of the heel where the Achilles tendon attaches. This structural abnormality is the static factor that sets the stage for dynamic and external causes to trigger inflammation and pain.
Biomechanical Stress Factors
Beyond the static bone structure, dynamic forces generated during movement significantly contribute to the irritation and progression of the deformity. A tight Achilles tendon is a frequently cited biomechanical factor, often due to a shortened calf muscle complex. When the tendon lacks flexibility, movement causing ankle dorsiflexion, such as walking, pulls the tendon taut. This tension compresses the bursa and the bony prominence against the heel bone, leading to friction and inflammation.
Specific patterns of gait also intensify the mechanical stress on the posterior heel. A tendency to walk on the outside of the heel, often associated with high-arched feet, increases the risk. This outward rolling, or supination, exposes the upper, outer corner of the heel bone to excessive pressure during the foot’s push-off phase. Conversely, excessive pronation, where the foot rolls inward, also contributes to abnormal tension and stress on the Achilles tendon.
Repetitive activity, particularly high-impact exercise, exacerbates the stress on the heel. Activities like running, sprinting, and sports involving frequent push-off motions place a greater load on the heel and Achilles tendon insertion. This constant strain and resulting repetitive microtrauma accelerate the friction between the tendon, the bursa, and the bony enlargement. The cumulative effect of these dynamic forces transforms a structurally predisposed heel into a symptomatic condition.
The Critical Role of Footwear
For a predisposed individual, the type of footwear worn acts as the most common trigger for symptomatic Haglund’s deformity. The mechanism involves direct friction and pressure from the shoe’s heel counter, the rigid material at the back of the shoe. When the foot moves inside a stiff-backed shoe, the material constantly rubs against the existing bony prominence, causing irritation to the soft tissues.
The condition earned its informal name, “pump bump,” because high-heeled pumps are a frequent culprit. Any shoe with a rigid, non-yielding back can cause the problem, including men’s dress shoes, ice skates, hiking boots, and stiff-backed work boots. The unyielding nature of the shoe counter traps the soft tissue and bone, creating a painful cycle of rubbing that leads to inflammation of the bursa.
Shoes that lack proper cushioning or support can also compound existing biomechanical issues, even without a rigid heel counter. When a shoe fails to adequately support the arch or control the foot’s motion, it increases internal friction and stress on the posterior heel. The interaction between a structurally prominent heel bone and the irritating pressure of an ill-fitting or rigid shoe often causes the deformity to become a painful, chronic condition.