Haemophilia

Haemophilia—commonly known as “the bleeding disorder”—is a genetically determined defect of blood coagulation. Because it is inherited in an X-linked recessive manner, haemophilia manifests almost exclusively in males, with very few exceptions. Women, as so-called carriers, more often show reduced clotting activity, but severe forms of haemophilia and extreme bleeding complications are not observed due to the presence of a second, healthy X chromosome. In around 30% of all cases, haemophilia is not inherited but arises from a spontaneous mutation.

A deficiency or functional defect of clotting factor VIII (Haemophilia A – prevalence approx. 1:10,000) or IX (Haemophilia B – prevalence approx. 1:25,000) leads to an increased tendency to bleed. Patients’ blood clots only with a delay or not at all, resulting in bleeding not only after trauma but also spontaneously into muscles and joints. The ankle, knee, and elbow joints are most frequently affected. Joint bleeds typically present with pain, swelling, warmth, and reduced range of motion. Even a single joint bleed can cause structural and neuromuscular changes in the affected joint. Recurrent bleeding into the same joint often culminates in so-called haemophilic arthropathy.

Haemophilic arthropathy is a secondary, inflammatory form of osteoarthritis and is the most common joint disorder in people with haemophilia. As it progresses, further functional adaptations of the musculoskeletal system occur—such as loss of joint mobility, contractures, and atrophy of periarticular muscles—leading to reduced physical performance. In addition to diminished coordination and muscle strength around the joints, people with haemophilia generally exhibit lower overall physical activity and, consequently, reduced endurance capacity. The motor abilities of strength, coordination, and flexibility are crucial for maintaining joint function. Deficits in these areas increase mechanical load on the affected joint and, in turn, raise the risk of bleeding—creating a vicious cycle of more frequent bleeds, deterioration of joint structure and function, and declining physical performance.

A growing number of studies now demonstrate the positive effects of targeted exercise on performance and quality of life in people with haemophilia. For this reason, structured exercise therapy has become an integral component of today’s treatment guidelines for haemophilia.

Classification of haemophilia severity according to the residual activity of the respective coagulation factor.