Pain and structural alterations in knee joints in patients with haemophilia

IntroductionPatients with haemophilia (PwH) suffer from haemophilic arthropathy which leads to an enhanced pain sensitivity. The aim of this study was to determine whether the individual pain condition in terms of pressure pain thresholds (PPT) at the knee joints is linked to changes of underlying anatomical structures in PwH. Material and methodsEleven landmarks at both knee joints of 36 PwH and 36 controls were examined in terms of PPT and ultrasound sonography (US). PPT were used to generate four groups: pain sensitive and insensitive knees of PwH and controls. ResultsPPT of the knee joints were significantly decreased at all landmarks in PwH when compared to controls (P.004). US findings revealed that especially osteophytes are more pronounced in pain-sensitive knees of PwH in comparison with pain-insensitive knees of PwH or pain-(in)sensitive knees of controls. The synovia tissue was also thickened in PwH when PPT was altered. In contrast to findings in osteoarthritis-related pain, no differences between the groups were found regarding effusion, whether assessed, for example on the distal edge of m. vastus lateralis (P=.893) or on the lateral joint space (P=.417). ConclusionParticular degenerative changes in terms of osteophytes and thickness of synovial tissue are associated with an enhanced pain sensitivity in PwH. Altered PPT which were not associated with structural findings may be an indicator for a complex peripheral and/or central sensitization of the affected joints in PwH. The role of this mechanism should be clarified in further studies.