ORIGINAL ARTICLE Musculoskeletal Ankle muscle activation in people with haemophilia E. KURZ,* C. ANDERS, † M. HERBSLEB, ‡ C. PUTA, ‡ D. CZEPA* and T. HILBERG* *Department of Sports Medicine, University of Wuppertal, Wuppertal, Germany; †Division for Motor Research, Pathophysiology and Biomechanics, Clinic for Trauma, Hand and Reconstructive Surgery, University Hospital Jena, Jena, Germany; and ‡Department of Sports Medicine and Health Promotion, Friedrich-Schiller-University Jena, Jena, Germany Summary. Since normative surface EMG (SEMG) values for muscles acting at the knee joint are available for people with haemophilia, increasing interest is noticeable for other joints affected by haemophilic arthropathy. Adequate activity of shank muscles is an important key for appropriate postural control. The aim of this study was to determine differences in muscle activation patterns of lower leg muscles between people with and without haemophilia during upright standing. SEMG of tibialis anterior (TA), fibularis longus (FL), lateral (LG) and medial (MG) heads of gastrocnemius, and soleus (SO) muscles of both sides were recorded in 25 haemophilic patients (H) and 25 non-haemophilic control subjects (C) while standing on even ground. The Gilbert-Score was used to assign sides to major (H-MA) and minor (H-MI) affected ankle joints in H. To normalize the SEMG amplitudes, amplitude ratios (percentage of cumulated activity) were calculated. Compared to controls, TA ratios showed higher and MG reduced levels in both H groups (P < 0.01). In the H-MA subgroup of H, FL also joined the TA behaviour whereas SO had similar activation direction as MG. Although possible descending influences from the knee joints cannot be excluded, this can be interpreted as a compensational mechanism due to the severity of the orthopaedic status of the ankle, which with increasing heaviness is accompanied by reduced plantar flexion capability. However, ankle joint integrity appears to be reduced in H, with TA and MG seeming to play key roles for neuromuscular control of upright posture. Keywords: ankle, arthropathy, haemophilia, surface EMG, upright standing Introduction The hallmark of people suffering from severe haemo- philia is recurrent bleeding into joints. Particularly, the knees, ankles and elbows are already affected in early age. If these resulting haemarthroses are treated inade- quately or even not treated at all, joint damage occurs, leading to arthropathy in the following decades of life. Joint space narrowing and joint deformity are com- mon orthopaedic problems in haemophilia. Prevention of arthropathy in haemophilic patients (H) is possible by replacing the deficient clotting factor at an early stage of life, best done before any significant joint destruction has occurred [1]. Evidence exists that pro- phylactic therapy (primary prophylaxis) is most benefi- cial for the prevention of haemophilic arthropathy [1]. According to Rodriguez-Merchan [2], evidence exists that supports the idea that “avoiding or minimizing joint loading might help protecting against haemophilic arthropathy”. However, minimizing joint load might not be the only way to break the “vicious circle” of joint destruction in people with haemophilia [for review see 3]. Whenever someone reduces the demand upon a specific tissue, it undoubtedly leads to a maladaptation of the respective structures [4]. In contrast, adequately conditioned muscles are able to protect the joints from progressive degeneration [5,6]. Thus, from a more holistic point of view, primary prophylaxis combined with individually adjusted exercise regimes [7–9] might have a more powerful effect on the prevention of haem- ophilic arthropathies than treatment with coagulation factors alone. The accurate evaluation of the joint condition is a prerequisite for any correct therapeutic approach. Therefore, joint conditions need to be precisely staged. This impacts the individual application of prophylaxis and dosage of sports therapy. The severity of impaired joint mobility should be determined in comparison with normal reference values. Unfortunately, there are little published data describing physiological joint Correspondence: Eduard Kurz, Department of Sports Medicine, University of Wuppertal, Pauluskirchstr. 7, 42285 Wuppertal, Germany. Tel.: +49 202 439-5912; fax: +49 202 439-5910; e-mails: e.kurz@uni-wuppertal.de; sportmedizin@uni-wuppertal.de Accepted after revision 3 April 2012 948 © 2012 Blackwell Publishing Ltd Haemophilia (2012), 18, 948–954 DOI: 10.1111/j.1365-2516.2012.02852.x