Isokinetic muscle strength differences in patients with mucopolysaccharidosis I, II, and VI

Article type: Research Article

Authors: Taylor, Natalie E. | Dengel, Donald R.^; | Lund, Troy C. | Rudser, Kyle D. | Orchard, Paul J. | Steinberger, Julia | Whitley, Chester B. | Polgreen, Lynda E.

Affiliations: School of Medicine and Public Health, University of Wisconsin, WI, USA | School of Kinesiology, University of Minnesota, Minneapolis, MN, USA | Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA | Division of Pediatric Blood and Marrow Transplantation, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA | Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, USA | Division of Pediatric Cardiology, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA | Division of Pediatric Genetics and Metabolism, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA | Division of Pediatric Endocrinology, Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN, USA

Note: [] Corresponding author: Natalie Taylor, University of Wisconsin, Health Science Learning Center, 750 Highland Ave., Madison, WI 53705, USA. Tel.: +1 920 562 0302; E-mail: ntaylor4@wisc.edu

Abstract: PURPOSE: To determine muscular strength differences in patients with MPS-I, II, and VI versus age- and sex-matched healthy controls. METHODS: Dominant leg isokinetic knee extension strength was measured at 90 and 120 degrees per second (d/s) using a dynamometer in 30 subjects with MPS and 42 controls (5–16 yrs). MPS-I was further divided into MPS-IA (attenuated) and MPS-IH (severe). Strength measures analyzed were peak torque (PkT), peak torque per unit body weight (PkT/BW) and per unit lean body mass (PkT/LBM), and average power (AP). RESULTS: Following adjusting strength measures for age, MPS-IH and MPS-II had significantly lower strength measures for all variables at both angular velocities. MPS-VI had significantly lower PkT, PkT/LBM, and AP compared to controls at 90 and 120d/s. In contrast, MPS-IA was not significantly different from controls for any strength variable at either angular velocity. CONCLUSION: The results of this study suggest that decrements in skeletal muscle strength depend on MPS diagnosis and severity of disease. Children with MPS-IH demonstrate the greatest difference in muscular strength compared to healthy controls.

Keywords: Mucopolysaccharidosis, strength, isokinetic

DOI: 10.3233/PRM-140305

Journal: Journal of Pediatric Rehabilitation Medicine, vol. 7, no. 4, pp. 353-360, 2014