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Published on: February 1, 2018
Quantitative Evaluation of Lower Extremity Joint Contractures in Spinal Muscular Atrophy: Implications for Motor
Rachel Salazar1, Jacqueline Montes, Sally Dunaway Young
1Departments of Neurology (Drs Salazar, Montes, Young, Chiriboga, and De Vivo) and Rehabilitation and Regenerative Medicine (Drs Montes and Young), Columbia University Medical Center, New York, New York; Departments of Biostatistics and Computational Biology (Dr McDermott) and Neurology (Mr Martens and Dr McDermott), University of Rochester, Rochester, New York; Departments of Neurology (Dr Darras) and Physical Therapy and Occupational Therapy Services (Drs Pasternak and Mirek and Ms Quigley), Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; Division of Neurology (Dr Tennekoon) and Department of Physical Therapy (Dr Glanzman), The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania; Division of Neurology (Mr Civitello and Dr Finkel), Nemours Children's Hospital, Orlando, Florida; Department of Neurology (Mr Gee, Ms Duong, and Dr Day), Stanford University School of Medicine, Palo Alto, California; Department of Paediatric Neurology (Mss Mazzone, Coratti, and Fanelli, Messrs De Sanctis and Forcina, and Dr Mercuri), Catholic University, Rome, Italy; Dubowitz Neuromuscular Centre (Mss Main and Ramsey and Drs Scoto and Muntoni), UCL Great Ormond Street Institute of Child Health, London, United Kingdom; John Walton Muscular Dystrophy Research Centre (Dr Mayhew and Mr Muni Lofra), Institute of Genetic Medicine, Newcastle University, Newcastle, United Kingdom.
Purpose:
To quantitatively describe passive lower extremity range of motion in participants with spinal muscular atrophy (SMA) types 2 and 3, and to establish preliminary thresholds to identify individuals at risk for performing poorly on disease-specific motor function outcome measures.
Methods:
Eighty participants with SMA types 2 and 3, enrolled in an international multicenter natural history study, were evaluated with lower extremity range of motion testing and the Hammersmith Functional Motor Scale-Expanded.
Results:
A hip extension joint angle of -7.5° or less for SMA type 2 and 0° or less for SMA type 3 identified diminished motor ability with good sensitivity. For knee extension, a joint angle of -9.0° or less for SMA type 2 or 0° or less for SMA type 3 was similarly sensitive.
Conclusions:
Minimal hip and knee joint contractures were associated with diminished motor ability. Clinical trial designs should consider the effect of contractures on motor function.
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