Abstract des Autors

Introduction: Recurrent bleeding episodes in patients with haemophilia (PWH) lead to joint alterations and therewith disturbed muscle coordination patterns. Major weight‐bearing joints are affected most. However, possible effects on trunk muscle activity have not been examined so far. The objective of this work was to study consequences of haemarthropathy on characteristics of trunk muscles in PWH while standing on surfaces with different mechanical properties. Methods: Surface EMG of internal oblique (IO) and multifidus (MF) muscles were bilaterally recorded during a natural bilateral stance in 20 PWH with severe haemophilia A [age: 42 years (SD: 10)] and 25 non‐haemophilic controls [NHC, 43 (12)]. Amplitude ratios, a symmetry index between sides and the co‐activation ratio of IO over MF served as outcome measures and compared standing on three different surfaces (stable, soft, unsteady). Results: PWH revealed markedly restricted lower extremity joints (P < 0.001), but without any hint of back pain. Neither result revealed significant main or interaction effects of ‘group’ (P > 0.24). Group‐independent analyses showed amplitude ratios (MF: P < 0.05) as well as symmetry indices (MF: P < 0.02) significantly altered by ‘surface’ in NHC only. Effects of utilizing soft vs. unsteady surfaces were not detectable (P > 0.77). Conclusion: Utilizing unstable surfaces does not lead to altered trunk muscle activity in PWH. Differently than expected, a quite similar behaviour of lower trunk muscles in terms of applied indices can be found in PWH and NHC. Ascending alterations of muscle coordination in PWH could not be verified.