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Peroneus longus and the midfoot in children: EMG normative data
Abstracts / Gait & Posture 36 (2012) S1–S101
tions in children with cerebral palsy (CP). This muscle characteristic is however scarcely investigated in this population. Recently a study reported an unexpected lower fatigability in children with CP compared to typically developing (TD) children. One possible explanations of this finding is the lower maximal muscle strength in the CP group. The purpose of this study is to investigate muscle fatigability in three groups of subjects with different maximal strength levels: children with CP, TD children and young adults. Patients/materials and methods: Seven children with spastic cerebral palsy (gross motor function classification system [GMFCS] levels I [n = 2] and II [n = 5], age: 9 ± 2 yr, six male), nine TD children (age: 10 ± 2 yr, six male) and 10 young adults (age: 22 ± 3 yr, seven male). All subjects performed an isokinetic protocol that was described by Moreau et al. [1] consisting of 35 maximal isokinetic knee flexion and extension contractions at 60◦ /s. Muscle fatigability was described as the rate of decline between the highest and lowest peak extension and flexion torque relative to the maximal torque. Results: As expected peak torque of both knee flexion and extension (expressed in Nm/kg) was significantly different between groups showing the highest peak values in young adults, and the lowest values in the children with CP. Muscle fatigability also differed between groups with the young adult group showing the greatest decline in peak torque while the children with CP showed the lowest decline in peak torque, which may be indicative of lower muscle fatigability. Discussion and conclusion: Our results confirmed earlier findings that children with CP have better resistance to muscle fatigue than TD children. The noticeably larger decline of peak torque over 35 maximal contraction in the young adults also confirmed that higher muscle fatigability coincides with higher peak strength levels. These findings may be associated to different metabolic properties of stronger muscles, but the limited ability of the children with CP to perform maximal strength exertions can affect the current findings and may have violated the validity of the applied protocol in this study. To further explore the mechanisms of muscle fatigability in children with CP, the application of an endurance protocol with fixed submaximal contractions is recommended. Disclosure: No significant relationships. Reference [1] Moreau N, Damiano DL. A feasible and reliable muscle fatigue assessment protocol for individuals with cerebral palsy. Pediatric Physical Therapy 2008;20:59–65.
doi:10.1016/j.gaitpost.2011.10.290 P18 Peroneus longus and the midfoot in children: EMG normative data C. Boulay 1,∗ , V. Pomero 2 , E. Viehweger 2 , G. Authier 2 , E. Castanier 2 , Y. Glard 2 , B. Chabrol 3 , J. Jouve 2 , G. Bollini 2 , M. Jacquemier 2 1
Gait Lab, Pediatric Surgery Department and Pediatric Neurology Department, CHU Timone Enfants, Marseille, France 2 Gait Lab, Pediatric Orthopaedic Surgery Department, CHU Timone Enfants, Marseille, France 3 Pediatric Neurology Department, CHU Timone Enfants, Marseille, France Introduction: The EMG overactivity of peroneus longus (PL) is described by Young [1] as the major deforming force in spastic midfoot break in adult after stroke. Before to test this hypothesis in children with cerebral palsy (CP), it was necessary to provide
S65
the normal EMG activity of PL in children without neuromuscular disorders. These data are not studied in literature. Patients/materials and methods: 1104 strides of 21 children (age 6.5 yr ± 1) without neuromuscular disorders were examined using surface EMG (ZeroWire, Aurion) during walking. The PL activity was normalized as a percentage during strides. A software selected the more repeatable strides. The onset, offset activity of rectified raw EMG signal was detected by a manual selection: the threshold was 20 V [3,4]. Results: Resulting in 1104 normal strides: the mean toe off was at 62.8%, the PL onset activity was at 26.3% in midstance and the offset at 51.7% during terminal stance. There was never activity during swing phase. Discussion and conclusion: These data confirmed the PL activation as a locking effect on midfoot, in midstance during the ankle rocker for progression and without motor action on the ankle [2,5,6]: PL supports the longitudinal and transversal arches. In terminal stance during forefoot rocker for progression, PL has a locking effect on the first ray: the forefoot is stabilising during the heel rise. It prevents excessive inversion thus maintaining the first metatarsal down on the ground. PL maintains the stabilisation of the first and second ray by a pronation to counteract the lift effect of the supination muscles. The PL contraction should be rather isometric. The relation between PL overactivity and midfoot break has to be assessed in CP children. Disclosure: No significant relationships. References [1] [2] [3] [4]
Young. Foot Ankle 1990;10(6):317–24. Johnson. Foot Ankle Surg 1999;38(5):313–21. Santili. Am J Sports Med 2005;33(8):1183–7. Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle. Philadelphia: Davis; 1989. [5] Perry. J Bone Joint Surg 1974;56–A(3):511–20. [6] Guillot. Bull Assoc Anat 1979;63(183):411–24.
doi:10.1016/j.gaitpost.2011.10.291 P19 One-year gait analysis study in spastic diplegic children after selective dorsal rhizotomy E. Carraro 1 , S. Gualdi 2,∗ , V. Marconi 1 , M. Santin 1 , A. Martinuzzi 1 , S. Zeme 3 , E. Trevisi 1 1 f. Fabbri” Posture and Motion Analysis Laboratory, “E. Medea” Scientific Institute – “La Nostra Famiglia” Association, Conegliano (TV), Italy 2 f. Fabbri” Posture and Motion Analysis Laboratory, “E. Medea” Scientific Institute – “La Nostra Famiglia” Association, Conegliano (TV)/Italy 3 Neurosurgery Department, University Hospital Company“Molinette San Giovanni Battista”, Torino, Italy
Introduction: Alterations of the central nervous system, which produce the characteristic features of cerebral palsy (CP), result in gait deviations due to the presence of reduced selective muscle control, abnormal muscle tone, imbalance between muscle agonists and antagonists across joints. Spasticity has been considered to be a main contributor to both the impairment of function and the decreased longitudinal muscle growth in children with spastic CP, leading to deformity. The only treatment option to reduce spasticity permanently is selective dorsal rhizotomy (SDR) [1,2]. We were interested whether CP subjects show significant changes in gait pattern after SDR. Patients/materials and methods: We recruited children with neuroimaging evidence of periventricular leukomalacia, clinical diagnosis of spastic diplegia and ambulation ability with or with-
tions in children with cerebral palsy (CP). This muscle characteristic is however scarcely investigated in this population. Recently a study reported an unexpected lower fatigability in children with CP compared to typically developing (TD) children. One possible explanations of this finding is the lower maximal muscle strength in the CP group. The purpose of this study is to investigate muscle fatigability in three groups of subjects with different maximal strength levels: children with CP, TD children and young adults. Patients/materials and methods: Seven children with spastic cerebral palsy (gross motor function classification system [GMFCS] levels I [n = 2] and II [n = 5], age: 9 ± 2 yr, six male), nine TD children (age: 10 ± 2 yr, six male) and 10 young adults (age: 22 ± 3 yr, seven male). All subjects performed an isokinetic protocol that was described by Moreau et al. [1] consisting of 35 maximal isokinetic knee flexion and extension contractions at 60◦ /s. Muscle fatigability was described as the rate of decline between the highest and lowest peak extension and flexion torque relative to the maximal torque. Results: As expected peak torque of both knee flexion and extension (expressed in Nm/kg) was significantly different between groups showing the highest peak values in young adults, and the lowest values in the children with CP. Muscle fatigability also differed between groups with the young adult group showing the greatest decline in peak torque while the children with CP showed the lowest decline in peak torque, which may be indicative of lower muscle fatigability. Discussion and conclusion: Our results confirmed earlier findings that children with CP have better resistance to muscle fatigue than TD children. The noticeably larger decline of peak torque over 35 maximal contraction in the young adults also confirmed that higher muscle fatigability coincides with higher peak strength levels. These findings may be associated to different metabolic properties of stronger muscles, but the limited ability of the children with CP to perform maximal strength exertions can affect the current findings and may have violated the validity of the applied protocol in this study. To further explore the mechanisms of muscle fatigability in children with CP, the application of an endurance protocol with fixed submaximal contractions is recommended. Disclosure: No significant relationships. Reference [1] Moreau N, Damiano DL. A feasible and reliable muscle fatigue assessment protocol for individuals with cerebral palsy. Pediatric Physical Therapy 2008;20:59–65.
doi:10.1016/j.gaitpost.2011.10.290 P18 Peroneus longus and the midfoot in children: EMG normative data C. Boulay 1,∗ , V. Pomero 2 , E. Viehweger 2 , G. Authier 2 , E. Castanier 2 , Y. Glard 2 , B. Chabrol 3 , J. Jouve 2 , G. Bollini 2 , M. Jacquemier 2 1
Gait Lab, Pediatric Surgery Department and Pediatric Neurology Department, CHU Timone Enfants, Marseille, France 2 Gait Lab, Pediatric Orthopaedic Surgery Department, CHU Timone Enfants, Marseille, France 3 Pediatric Neurology Department, CHU Timone Enfants, Marseille, France Introduction: The EMG overactivity of peroneus longus (PL) is described by Young [1] as the major deforming force in spastic midfoot break in adult after stroke. Before to test this hypothesis in children with cerebral palsy (CP), it was necessary to provide
S65
the normal EMG activity of PL in children without neuromuscular disorders. These data are not studied in literature. Patients/materials and methods: 1104 strides of 21 children (age 6.5 yr ± 1) without neuromuscular disorders were examined using surface EMG (ZeroWire, Aurion) during walking. The PL activity was normalized as a percentage during strides. A software selected the more repeatable strides. The onset, offset activity of rectified raw EMG signal was detected by a manual selection: the threshold was 20 V [3,4]. Results: Resulting in 1104 normal strides: the mean toe off was at 62.8%, the PL onset activity was at 26.3% in midstance and the offset at 51.7% during terminal stance. There was never activity during swing phase. Discussion and conclusion: These data confirmed the PL activation as a locking effect on midfoot, in midstance during the ankle rocker for progression and without motor action on the ankle [2,5,6]: PL supports the longitudinal and transversal arches. In terminal stance during forefoot rocker for progression, PL has a locking effect on the first ray: the forefoot is stabilising during the heel rise. It prevents excessive inversion thus maintaining the first metatarsal down on the ground. PL maintains the stabilisation of the first and second ray by a pronation to counteract the lift effect of the supination muscles. The PL contraction should be rather isometric. The relation between PL overactivity and midfoot break has to be assessed in CP children. Disclosure: No significant relationships. References [1] [2] [3] [4]
Young. Foot Ankle 1990;10(6):317–24. Johnson. Foot Ankle Surg 1999;38(5):313–21. Santili. Am J Sports Med 2005;33(8):1183–7. Kimura J. Electrodiagnosis in Diseases of Nerve and Muscle. Philadelphia: Davis; 1989. [5] Perry. J Bone Joint Surg 1974;56–A(3):511–20. [6] Guillot. Bull Assoc Anat 1979;63(183):411–24.
doi:10.1016/j.gaitpost.2011.10.291 P19 One-year gait analysis study in spastic diplegic children after selective dorsal rhizotomy E. Carraro 1 , S. Gualdi 2,∗ , V. Marconi 1 , M. Santin 1 , A. Martinuzzi 1 , S. Zeme 3 , E. Trevisi 1 1 f. Fabbri” Posture and Motion Analysis Laboratory, “E. Medea” Scientific Institute – “La Nostra Famiglia” Association, Conegliano (TV), Italy 2 f. Fabbri” Posture and Motion Analysis Laboratory, “E. Medea” Scientific Institute – “La Nostra Famiglia” Association, Conegliano (TV)/Italy 3 Neurosurgery Department, University Hospital Company“Molinette San Giovanni Battista”, Torino, Italy
Introduction: Alterations of the central nervous system, which produce the characteristic features of cerebral palsy (CP), result in gait deviations due to the presence of reduced selective muscle control, abnormal muscle tone, imbalance between muscle agonists and antagonists across joints. Spasticity has been considered to be a main contributor to both the impairment of function and the decreased longitudinal muscle growth in children with spastic CP, leading to deformity. The only treatment option to reduce spasticity permanently is selective dorsal rhizotomy (SDR) [1,2]. We were interested whether CP subjects show significant changes in gait pattern after SDR. Patients/materials and methods: We recruited children with neuroimaging evidence of periventricular leukomalacia, clinical diagnosis of spastic diplegia and ambulation ability with or with-