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Reduced muscle mass adversely affects bone development and strength in ambulant adolescents and young adults with spastic cerebral palsy
Abstracts / Gait & Posture 30S (2009) S1–S153
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are ADD and PF at HC whereas DF is seen at FF and HO. M. tibialis posterior has PF as primary action at HC for both bones as well as at FF for calcaneus. Talus performs ER at FF and ADD at HO whereas calcaneus performs ABD at HO. Secondary functions are ADD and IR at HC. At FF, ER of calcaneus and ADD combined with PF of talus is found. AT HO, PF of talus is seen. Primary action of M. flexor hallucis is PF at HC, IR at FF and DF at HO. Secondary function shows a clear tendency to IR and ABD at HC but is more variable at FF and HO. Mm. peronei shows a variable pattern between different positions and bones. Discussion Primary and secondary muscle function of six muscle groups is defined. As observed muscle function differs for the three foot positions, it is concluded that muscle action on the hind foot complex depends on the actual foot position and therefore the phase in the gait cycle. doi:10.1016/j.gaitpost.2009.08.032
Fig. 1. PCAI values for joint specific phases of gait; asymptomatic and pre-/post-TKA values are shown. The PCAI algorithm is imbedded.
O29 Periarticular muscle coactivation in total knee arthroplasty patients and controls during gait
and time main effects and interactions for the PCAI scores (SPSS 17).
Vassilios Vardaxis 1,∗ , Craig Mahoney 2 , Zack Singsank 1 , Jennifer Haden 1
Results Clinical measures for the TKA group at 3-month post-surgery showed significant improvements in pain and physical function (SF-36). Gait velocity and stride length also improved; however, the knee ROM during stance remained unchanged. PCAI significant (p < .05) group effects were found for the hip (both), knee (1, 2) and ankle (1) phases (Fig. 1). The knee coactivation indices during loading response were the highest for all subjects underlining the knee stability demand during weight transfer. There were no significant time and interaction effects on the PCAI values.
1 2
Des Moines University, Des Moines, IA, United States Iowa Orthopaedic Center, PC, Des Moines, IA, United States
Summary We assessed the periarticular coactivation (PCAI) of total knee arthroplasty (TKA) patients before and after surgery and compared it to asymptomatic controls during self-selected speed gait. Conclusions The PCAI showed higher coactivation indices at the hip, knee and ankle joints of the TKA group pre- and post-surgery. The knee and ankle indices were higher at early stance and for the hip throughout the gait cycle. The higher coactivation pattern persisted 3 months post-surgery. Introduction Neuromuscular deviations in the activation pattern of the knee muscles occur in patients with varying degrees of OA and controls; however the coactivation level at the adjacent joints during gait and the change in coactivation after TKA has not been established. Since lower extremity function is coupled across multiple joints and segments in 3D motion and time, deviations in position/motion at a joint affects adjacent and even remote joints. However, neuromuscular coactivation is assessed in knee joint muscles only, one pair at a time, which is not integrating the multitude of synergistic muscles that cross the joint and often cross the hip or ankle as well. We present new methodology to assess periarticular coactivation indices (PCAI) for all joint specific synergistic muscles over distinct phases of the gait cycle for a group of OA patients slated for TKA and controls. Patients/materials and methods Kinematic, kinetic and electromyographic data were collected on 20 TKA patients (7M and 13F) and 12 age- and gender-matched controls at baseline and 3 months post-surgery during gait. The PCAI for each joint was calculated for two hip, three knee, and four ankle specific phases during gait using synergistic muscle groups: Hip – rectus femoris, semitendinosus and biceps femoris; knee – rectus femoris, vastus medialis, vastus lateralis semitendinosus, biceps femoris and gastrocnemius; and ankle – gastrocnemius, soleus and tibialis anterior. A mixed ANOVA model tested for group
Discussion The higher coactivation pattern in OA patients is not isolated at the involved joint but rather across all joints of the lower extremity. This coactivation is lower extremity wide and phasic, rather than joint specific and gait cycle wide phenomenon. PCAI analysis technique is promising in assessing the long-term persistence of coactivation after surgery. doi:10.1016/j.gaitpost.2009.08.033 O30 Reduced muscle mass adversely affects bone development and strength in ambulant adolescents and young adults with spastic cerebral palsy Nicola Fry 1,3 , Steven Gough 1,3,∗
Keevil 2,3 , Adam
Shortland 1,3 , Martin
1
One Small Step Gait Laboratory, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom 2 Department of Medical Physics, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom 3 Division of Imaging Sciences, King’s College, London, United Kingdom Summary Tibial and cortical areas and muscle cross-sectional area (MCSA) were measured using MRI in nine independently ambulant subjects with spastic cerebral palsy (SCP) and in nine age and sex-matched control subjects. The Gillette Gait Index (GGI) was also calculated in the SCP group. The SCP group had a marked reduction in total tibial area and in cortical area, with a reduction in cortical area as a proportion of total tibial area. Tibial and cortical area showed no
S22
Abstracts / Gait & Posture 30S (2009) S1–S153
correlation with the GGI. There was no difference in the relationship between cortical area and MCSA between SCP and control groups. Conclusions Tibial growth and cortical development and hence tibial strength is reduced in independently ambulant subjects with SCP because of a reduction in the muscle forces acting on the tibia. Introduction Bone strength is related to a combination of bone density and bone geometry, in particular to bone diameter and cortical area [1]. Muscle cross-sectional area (MCSA) appears to be the primary explanatory variable for bone strength in children [2]; the effect of body mass on bone strength appears to be related to lean body mass rather than fat mass [3]. Ambulant children with SCP have been shown to have reduced muscle volumes [4]. We hypothesized that this reduction in muscle volume would be associated with an alteration in bone geometry in independently ambulant adolescents and young adults with SCP. Patients/materials and methods Nine ambulant subjects with SCP (seven with bilateral CP, two with unilateral CP, GMFCS I n = 4, GMFCS II n = 5), mean age 17.4y (range 14.6–22.3y) and nine age and sex-matched control subjects had MRI scans of their lower limbs. None of the subjects with CP had intervention in the year prior to the assessment. The involved side in the 2 subjects with unilateral CP was compared with the corresponding limb in the matched controls, giving a total of 16 limbs. The MRI images were collated and custom written software was used to assess tibial area (total, cortical and medullary) and tibial MCSA at the junction of the upper and mid-third of the tibia. The SCP subjects had three-dimensional gait analysis data collected using a Vicon motion capture system: from this, the Gillette Gait Index (GGI) was calculated for each subject. Results The subjects with CP were shorter (p < 0.0009) and lighter (p < 0.014) than those in the control group. In the control group, MCSA was related closely to body mass (r2 = 0.7596, p < 0.0001). Total tibial area and cortical area in the control group correlated best with limb length (r2 = 0.6121, p = 0.0003 and r2 = 0.6952, p < 0.0001, respectively). Total tibial area and cortical area were closely correlated in the control group (r2 = 0.85, p < 0.0001), with a moderate correlation between cortical area and MCSA (r2 = 0.438, p = 0.0052). The subjects with CP had a significant reduction in total tibial area and cortical area (both p < 0.0001) when normalized to limb length although no difference in trabecular area was noted between both groups (p = 0.782). Cortical area as a proportion of total tibial area was reduced in the SCP group compared to the control group (p < 0.0001). No correlation was noted between tibial or cortical area and the GGI in the SCP group. When normalized to body mass, MCSA was significantly reduced in the CP group (p < 0.0001). No difference was noted in the ratio between cortical area and MCSA in both groups (p = 0.2689). Discussion Independent ambulation in itself does not result in normal tibial development. The reduced total tibial area and in particular the reduction in cortical area imply reduced bone strength at skeletal maturity which may have adverse implications for the future in this group given the expected normal reduction in bone mass with age. Cortical mass did not differ when normalized to MCSA, supporting the hypothesis that it is the reduction in muscle force acting on bone which adversely affects bone growth and development in SCP.
References [1] Rauch F. Bone growth in length and width: the yin and yang of stability. J Musculoskel Neuronal Interact 2005;5:194–201. [2] Macdonald H, Kontulainen S, Petit M, Janssen P, McKay H. Bone strength and it’s determinants in pre-and early pubertal boys and girls. Bone 2006;39:598–608. [3] Petit MA, Beck TJ, Shults J, Zemel BS, Foster BJ, Leonard MB. Proximal femur bone geometry is appropriately adapted to lean mass in overweight children and adolescents. Bone 2005;36:568–76. [4] Fry NR, Gough M, McNee AE, Shortland AP. Changes in the volume and length of the medial gastrocnemius after surgical recession in children with spastic diplegic cerebral palsy. J Pediatr Orthop 2007;27:769–74.
doi:10.1016/j.gaitpost.2009.08.034 O31 EMG gait analysis of peroneus longus (PL) and gastrocnemius medialis (GM) in hemiplegic cerebral palsy (CP) among young children: Premature activation during swing phase controlling the equines Christophe Boulay 1,∗ , Vincent Pomero 1 , Sandrine Pagni 1 , Elke Viehweger 1 , Yann Glard 1 , Brigitte Chabrol 2 , Jean-Luc Jouve 1 , Gérard Bollini 1 , Michel Jacquemier 1 1
Gait Lab, Pediatric Orthopaedic Surgery Department, CHU Timone Enfants, Marseille, France 2 Pediatric Neurology Department, Marseille, France Summary The appropriate pre-position of the foot in terminal swing is a pre-requisite of a normal gait which is lost in the equinus pattern. Perry [1] determined the relationship between the premature activity of GM during swing phase prior to the stance onset and foot switch (FSW). This study assessed the premature activation of PL and GM and the correlation with the FSW during initial contact. In equinus valgus children, the PL premature activation was significantly earlier than GM in swing phase than in equinus varus children. These data are important for the treatment of equinus (botulinum toxin, orthosis, surgery, failure of surgery) and the pathophysiology of equinus (clinical, radiological). Conclusions EMG of the PL is mandatory in the equinus gait analysis. Introduction In open kinetic chain, the PL moves the first metatarsus head (M1) downward, pronates the fore-foot and produces a plantar flexion. In closed kinetic chain, the PL action supports the longitudinal and transversal arches. During gait, at midstance, after GM activation, PL prevents excessive inversion thus maintaining M1 down on the ground [2]. But the premature activation timing of PL and GM in equinus is not documented [3,4]. Patients/materials and methods Twenty children (age 5yrs ± 2) with hemiplegia were examined using surface EMG (ZeroWire, Aurion) during walking. The PL and GM activity were normalized as a percentage during swing phase prior to the onset of stance and correlated with FSW during the initial contact. 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 [5,6]. A paired t-test assessed the activity between PL and GM. Results There was not contracture of triceps surae: maximum passive ankle dorsiflexion (knee flexed/extended) averaged 22.5◦ /14◦ .
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are ADD and PF at HC whereas DF is seen at FF and HO. M. tibialis posterior has PF as primary action at HC for both bones as well as at FF for calcaneus. Talus performs ER at FF and ADD at HO whereas calcaneus performs ABD at HO. Secondary functions are ADD and IR at HC. At FF, ER of calcaneus and ADD combined with PF of talus is found. AT HO, PF of talus is seen. Primary action of M. flexor hallucis is PF at HC, IR at FF and DF at HO. Secondary function shows a clear tendency to IR and ABD at HC but is more variable at FF and HO. Mm. peronei shows a variable pattern between different positions and bones. Discussion Primary and secondary muscle function of six muscle groups is defined. As observed muscle function differs for the three foot positions, it is concluded that muscle action on the hind foot complex depends on the actual foot position and therefore the phase in the gait cycle. doi:10.1016/j.gaitpost.2009.08.032
Fig. 1. PCAI values for joint specific phases of gait; asymptomatic and pre-/post-TKA values are shown. The PCAI algorithm is imbedded.
O29 Periarticular muscle coactivation in total knee arthroplasty patients and controls during gait
and time main effects and interactions for the PCAI scores (SPSS 17).
Vassilios Vardaxis 1,∗ , Craig Mahoney 2 , Zack Singsank 1 , Jennifer Haden 1
Results Clinical measures for the TKA group at 3-month post-surgery showed significant improvements in pain and physical function (SF-36). Gait velocity and stride length also improved; however, the knee ROM during stance remained unchanged. PCAI significant (p < .05) group effects were found for the hip (both), knee (1, 2) and ankle (1) phases (Fig. 1). The knee coactivation indices during loading response were the highest for all subjects underlining the knee stability demand during weight transfer. There were no significant time and interaction effects on the PCAI values.
1 2
Des Moines University, Des Moines, IA, United States Iowa Orthopaedic Center, PC, Des Moines, IA, United States
Summary We assessed the periarticular coactivation (PCAI) of total knee arthroplasty (TKA) patients before and after surgery and compared it to asymptomatic controls during self-selected speed gait. Conclusions The PCAI showed higher coactivation indices at the hip, knee and ankle joints of the TKA group pre- and post-surgery. The knee and ankle indices were higher at early stance and for the hip throughout the gait cycle. The higher coactivation pattern persisted 3 months post-surgery. Introduction Neuromuscular deviations in the activation pattern of the knee muscles occur in patients with varying degrees of OA and controls; however the coactivation level at the adjacent joints during gait and the change in coactivation after TKA has not been established. Since lower extremity function is coupled across multiple joints and segments in 3D motion and time, deviations in position/motion at a joint affects adjacent and even remote joints. However, neuromuscular coactivation is assessed in knee joint muscles only, one pair at a time, which is not integrating the multitude of synergistic muscles that cross the joint and often cross the hip or ankle as well. We present new methodology to assess periarticular coactivation indices (PCAI) for all joint specific synergistic muscles over distinct phases of the gait cycle for a group of OA patients slated for TKA and controls. Patients/materials and methods Kinematic, kinetic and electromyographic data were collected on 20 TKA patients (7M and 13F) and 12 age- and gender-matched controls at baseline and 3 months post-surgery during gait. The PCAI for each joint was calculated for two hip, three knee, and four ankle specific phases during gait using synergistic muscle groups: Hip – rectus femoris, semitendinosus and biceps femoris; knee – rectus femoris, vastus medialis, vastus lateralis semitendinosus, biceps femoris and gastrocnemius; and ankle – gastrocnemius, soleus and tibialis anterior. A mixed ANOVA model tested for group
Discussion The higher coactivation pattern in OA patients is not isolated at the involved joint but rather across all joints of the lower extremity. This coactivation is lower extremity wide and phasic, rather than joint specific and gait cycle wide phenomenon. PCAI analysis technique is promising in assessing the long-term persistence of coactivation after surgery. doi:10.1016/j.gaitpost.2009.08.033 O30 Reduced muscle mass adversely affects bone development and strength in ambulant adolescents and young adults with spastic cerebral palsy Nicola Fry 1,3 , Steven Gough 1,3,∗
Keevil 2,3 , Adam
Shortland 1,3 , Martin
1
One Small Step Gait Laboratory, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom 2 Department of Medical Physics, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom 3 Division of Imaging Sciences, King’s College, London, United Kingdom Summary Tibial and cortical areas and muscle cross-sectional area (MCSA) were measured using MRI in nine independently ambulant subjects with spastic cerebral palsy (SCP) and in nine age and sex-matched control subjects. The Gillette Gait Index (GGI) was also calculated in the SCP group. The SCP group had a marked reduction in total tibial area and in cortical area, with a reduction in cortical area as a proportion of total tibial area. Tibial and cortical area showed no
S22
Abstracts / Gait & Posture 30S (2009) S1–S153
correlation with the GGI. There was no difference in the relationship between cortical area and MCSA between SCP and control groups. Conclusions Tibial growth and cortical development and hence tibial strength is reduced in independently ambulant subjects with SCP because of a reduction in the muscle forces acting on the tibia. Introduction Bone strength is related to a combination of bone density and bone geometry, in particular to bone diameter and cortical area [1]. Muscle cross-sectional area (MCSA) appears to be the primary explanatory variable for bone strength in children [2]; the effect of body mass on bone strength appears to be related to lean body mass rather than fat mass [3]. Ambulant children with SCP have been shown to have reduced muscle volumes [4]. We hypothesized that this reduction in muscle volume would be associated with an alteration in bone geometry in independently ambulant adolescents and young adults with SCP. Patients/materials and methods Nine ambulant subjects with SCP (seven with bilateral CP, two with unilateral CP, GMFCS I n = 4, GMFCS II n = 5), mean age 17.4y (range 14.6–22.3y) and nine age and sex-matched control subjects had MRI scans of their lower limbs. None of the subjects with CP had intervention in the year prior to the assessment. The involved side in the 2 subjects with unilateral CP was compared with the corresponding limb in the matched controls, giving a total of 16 limbs. The MRI images were collated and custom written software was used to assess tibial area (total, cortical and medullary) and tibial MCSA at the junction of the upper and mid-third of the tibia. The SCP subjects had three-dimensional gait analysis data collected using a Vicon motion capture system: from this, the Gillette Gait Index (GGI) was calculated for each subject. Results The subjects with CP were shorter (p < 0.0009) and lighter (p < 0.014) than those in the control group. In the control group, MCSA was related closely to body mass (r2 = 0.7596, p < 0.0001). Total tibial area and cortical area in the control group correlated best with limb length (r2 = 0.6121, p = 0.0003 and r2 = 0.6952, p < 0.0001, respectively). Total tibial area and cortical area were closely correlated in the control group (r2 = 0.85, p < 0.0001), with a moderate correlation between cortical area and MCSA (r2 = 0.438, p = 0.0052). The subjects with CP had a significant reduction in total tibial area and cortical area (both p < 0.0001) when normalized to limb length although no difference in trabecular area was noted between both groups (p = 0.782). Cortical area as a proportion of total tibial area was reduced in the SCP group compared to the control group (p < 0.0001). No correlation was noted between tibial or cortical area and the GGI in the SCP group. When normalized to body mass, MCSA was significantly reduced in the CP group (p < 0.0001). No difference was noted in the ratio between cortical area and MCSA in both groups (p = 0.2689). Discussion Independent ambulation in itself does not result in normal tibial development. The reduced total tibial area and in particular the reduction in cortical area imply reduced bone strength at skeletal maturity which may have adverse implications for the future in this group given the expected normal reduction in bone mass with age. Cortical mass did not differ when normalized to MCSA, supporting the hypothesis that it is the reduction in muscle force acting on bone which adversely affects bone growth and development in SCP.
References [1] Rauch F. Bone growth in length and width: the yin and yang of stability. J Musculoskel Neuronal Interact 2005;5:194–201. [2] Macdonald H, Kontulainen S, Petit M, Janssen P, McKay H. Bone strength and it’s determinants in pre-and early pubertal boys and girls. Bone 2006;39:598–608. [3] Petit MA, Beck TJ, Shults J, Zemel BS, Foster BJ, Leonard MB. Proximal femur bone geometry is appropriately adapted to lean mass in overweight children and adolescents. Bone 2005;36:568–76. [4] Fry NR, Gough M, McNee AE, Shortland AP. Changes in the volume and length of the medial gastrocnemius after surgical recession in children with spastic diplegic cerebral palsy. J Pediatr Orthop 2007;27:769–74.
doi:10.1016/j.gaitpost.2009.08.034 O31 EMG gait analysis of peroneus longus (PL) and gastrocnemius medialis (GM) in hemiplegic cerebral palsy (CP) among young children: Premature activation during swing phase controlling the equines Christophe Boulay 1,∗ , Vincent Pomero 1 , Sandrine Pagni 1 , Elke Viehweger 1 , Yann Glard 1 , Brigitte Chabrol 2 , Jean-Luc Jouve 1 , Gérard Bollini 1 , Michel Jacquemier 1 1
Gait Lab, Pediatric Orthopaedic Surgery Department, CHU Timone Enfants, Marseille, France 2 Pediatric Neurology Department, Marseille, France Summary The appropriate pre-position of the foot in terminal swing is a pre-requisite of a normal gait which is lost in the equinus pattern. Perry [1] determined the relationship between the premature activity of GM during swing phase prior to the stance onset and foot switch (FSW). This study assessed the premature activation of PL and GM and the correlation with the FSW during initial contact. In equinus valgus children, the PL premature activation was significantly earlier than GM in swing phase than in equinus varus children. These data are important for the treatment of equinus (botulinum toxin, orthosis, surgery, failure of surgery) and the pathophysiology of equinus (clinical, radiological). Conclusions EMG of the PL is mandatory in the equinus gait analysis. Introduction In open kinetic chain, the PL moves the first metatarsus head (M1) downward, pronates the fore-foot and produces a plantar flexion. In closed kinetic chain, the PL action supports the longitudinal and transversal arches. During gait, at midstance, after GM activation, PL prevents excessive inversion thus maintaining M1 down on the ground [2]. But the premature activation timing of PL and GM in equinus is not documented [3,4]. Patients/materials and methods Twenty children (age 5yrs ± 2) with hemiplegia were examined using surface EMG (ZeroWire, Aurion) during walking. The PL and GM activity were normalized as a percentage during swing phase prior to the onset of stance and correlated with FSW during the initial contact. 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 [5,6]. A paired t-test assessed the activity between PL and GM. Results There was not contracture of triceps surae: maximum passive ankle dorsiflexion (knee flexed/extended) averaged 22.5◦ /14◦ .