Summary. Knee haemarthroses are very common in the haemophiliac and often, despite infusion of the missing coagulation factor, synovitis develops. The warm swollen joint is maintained in the most comfortable position for the haemophiliac: flexion. Ambulation is achieved by planterflexion of the ankle joint and toewalking. As the chronic synovitis persists, the range of movement of the knee is affected, with loss of full extension. Development of radiological degenerative signs develop. The quadriceps muscle usually weaken due to disuse, but the hamstrings are active in maintaining the flexion of the joint. As the process continues, the tibia subluxes posteriorly on the condyles of the femur. The posterior capsule of the knee joint soon contracts, permanently limiting knee extension. A case is described on whom an Ilizarov device was used to gradually return the limb to a function position. This will allow the patient to complete his growth prior to a definitive orthopaedic procedure.