Influence of patellar position on the knee extensor mechanism in normal and crouched walking |
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| Institution: | 1. Department of Biomedical Engineering, University of Wisconsin-Madison, USA;2. Department of Mechanical Engineering, University of Wisconsin-Madison, USA;3. Gillette Children?s Specialty Healthcare, USA;4. University of Minnesota – Twin Cities, Department of Orthopaedic Surgery, USA;5. Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, USA;1. University of Maryland Baltimore School of Medicine, Department of Neurology, 110 S. Paca St, Baltimore, MD 21202, USA;2. IRCCS Fondazione Don Carlo Gnocchi ONLUS, Biomedical Technology Department, via Capecelatro 66, 20148 Milano, Italy;3. Politecnico di Milano, Department of Electronics, Information and Bioengineering, via Golgi 39, 20133 Milano, Italy;1. Department of Sports Medicine and Health Promotion, Friedrich-Schiller University Jena, Wöllnitzer Straße 42, D-07749 Jena, Germany;2. Center of Interdisciplinary Prevention of Diseases related to Professional Activities, Friedrich-Schiller University Jena, D-07737 Jena, Germany;3. Department of Sports and Motion Science, University Stuttgart, Allmandring 28, D-70569 Stuttgart, Germany;4. Department of Sports Management, University Bayreuth, Universitätsstraße 30, D-95440 Bayreuth, Germany;1. Department of Oral Cell Biology and Functional Anatomy, Academic Center for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands;2. MOVE Research Institute Amsterdam, University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands;3. Biomechanics Section, Department of Mechanical Engineering, KU Leuven, Leuven, Belgium;4. Department of Oral Kinesiology, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and VU University Amsterdam, Amsterdam, The Netherlands;1. INRIA Paris, 2 Rue Simone Iff, 75012 Paris, France;2. Sorbonne Universités, UPMC Univ. Paris 6, Laboratoire Jacques-Louis Lions, 75252 Paris, France;3. Medical R&D, WBL Healthcare, Air Liquide Santé International, 1 Chemin de la Porte des Loges, 78350 Les Loges-en-Josas, France;4. Department of Mechanical Engineering, Lafayette College, Easton, PA 18042, USA |
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| Abstract: | Patella alta is common in cerebral palsy, especially in patients with crouch gait. Correction of patella alta has been advocated in the treatment of crouch, however the appropriate degree of correction and the implications for knee extensor function remain unclear. Therefore, the goal of this study was to assess the impact of patellar position on quadriceps and patellar tendon forces during normal and crouch gait. To this end, a lower extremity musculoskeletal model with a novel 12 degree of freedom knee joint was used to simulate normal gait in a healthy child, as well as mild (23 deg min knee flexion in stance), moderate (41 deg), and severe (67 deg) crouch gait in three children with cerebral palsy. The simulations revealed that quadriceps and patellar tendon forces increase dramatically with crouch, and are modulated by patellar position. For example with a normal patellar tendon position, peak patellar tendon forces were 0.7 times body weight in normal walking, but reached 2.2, 3.2 and 5.4 times body weight in mild, moderate and severe crouch. Moderate patella alta acted to reduce quadriceps and patellar tendon loads in crouch gait, due to an enhancement of the patellar tendon moment arms with alta in a flexed knee. In contrast, patella baja reduced the patellar tendon moment arm in a flexed knee and thus induced an increase in the patellar tendon loads needed to walk in crouch. Functionally, these results suggest that patella baja could also compromise knee extensor function for other flexed knee activities such as chair rise and stair climbing. The findings are important to consider when using surgical approaches for correcting patella alta in children who exhibit crouch gait patterns. |
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| Keywords: | Cerebral palsy Patella position Patella alta Patella baja Knee extensor Moment arm |
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