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Effects of medial gastrocnemius relative fascicle excursion on stance phase plantarflexion work in children with cerebral palsy
Gait & Posture 49S (2016) 129–130
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
O112 presented in OS17: CP: Anatomy and physiology
Effects of medial gastrocnemius relative fascicle excursion on stance phase plantarflexion work in children with cerebral palsy Teresa [1_TD$IF]Martı´n[4_TD$IF] Lorenzo 1,2,*, Sergio Lerma[5_TD$IF] Lara 1,3 [1_TD$IF] 1
Hospital Infantil Universitario Nin˜o Jesu´s, Madrid, Spain Rey Juan Carlos University, Alcorco´n, Madrid, Spain 3 CSEU La Salle, Universidad Auto´noma de Madrid, Aravaca, Madrid, Spain 2
[(Fig._1)TD$IG]
Introduction: Contraction velocity has been associated to fascicle length (fL) or serial sarcomere number [1]. However, contrary to healthy children (TD), fL has shown no relationship to
Fig. 1. [3_TD$IF]Medial gastrocnemius muscle-tendon unit architecture measurments on ultrasdound image and graphical representation of ankle power during gait. Note that with dorsiflexion the miotendinous junction moves distally, thus tendon excursions are negative. * Corresponding author. E-mail address: [email protected] (T. Martı´n Lorenzo). http://dx.doi.org/10.1016/j.gaitpost.2016.07.189 0966-6362/
isometric power in children with cerebral palsy (CP) [2]. This might be related to inconsistent fL TD vs CP differences [3]. Furthermore, in-series sarcomere addition response to stretch may not occur in CP [4]. Recently, children with CP have shown shorter medial gastrocnemius fascicles undergoing longer relative fascicle excursions (RFE) throughout ROM than TD children, suggesting previously reported overstretched sarcomeres operating at nonoptimal lengths [4,5]. Furthermore, dynamic joint work has shown a strong correlation to muscle volume in CP [6]. Therefore, we believe RFE instead of fL would better correlate with dynamic joint work, or integral of power over time. Research question: Does medial gastrocnemius RFE correlate with plantarflexion work in children with CP? Methods: 18 children with CP (29 legs, 10.74 3.38 years, GMFCS I–III) were assessed. Stance phase plantarflexion work performance was obtained from 3D motion analysis data. Furthermore, 2D ultrasound was used to determine medial gastrocnemius RFE from resting ankle position (RJA) to maximum dorsiflexion (MDF) following ultrasound error reduction techniques [7,8]. Moreover, muscle belly length (bL) and tendon length (tL) were recorded to further inform findings (Fig. 1). Results: Measured RFE was (mean SE) 41.01 3.27%, similar to previous reports of 43.30% [5]. However, RFE was not correlated to plantarflexion work. Further data analysis revealed significant correlations to plantarflexion work. Independent variable
Dependent variable
MDF tL (% tibia length)
Total
MDF fL/bL[2_TD$IF] ratio
Late Stance + Work (J/kg)
MDF tL/fL ratio
Total
MDF fL/bL ratio
Total + Work (J/kg)
tL change (% RJA length)
Total
Work (J/kg)
0.45*
tL change (% RJA length)
Total + Work (J/kg)
0.44*
Work (J/kg) Work (J/kg)
r 0.57* 0.54** 0.52* 0.48*
Discussion: The lack of correlation between RFE and plantarflexion work may be associated to uncontrolled neural mechanisms and muscle structure parameters reflecting in-parallel sarcomeres which also contribute to joint work [6,9]. Muscle volume comprises in-parallel sarcomeres and has been significantly correlated to joint work in both TD and CP to the same extent [6]. Thus, muscle volume may better predict plantarflexion
130
T. Martı´n Lorenzo, S. Lerma Lara / Gait & Posture 49S (2016) 129–130
work independently of neural drive differences. Nevertheless, the ability to perform greater positive or negative work has been significantly associated to tendon excursion, MDF tendon length, MDF fascicle/belly length ratio, and tendon/fascicle length ratio and should thus be taken into account. References [1] Lieber. Muscle Nerve 2000;23:1647–66. [2] Moreau. Gait Posture 2012;35:154–8.
[3] [4] [5] [6] [7] [8] [9]
Barrett. Dev. Med. Child Neurol. 2010;52:794–804. Mathewson. Phys. Med. Rehabil. Clin. N. Am. 2015;26:57–67. Matthiasdottir. Clin. Biomech. 2014;29:458–62. Reid. Disabil. Rehabil. 2014;1–6. Maas. BMC Pediatr. 2012;12:38. Be´nard. Muscle Nerve 2009;52–665. Mockford. Pediatr. Phys. Ther. 2010;22:222–33.
Contents lists available at ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
O112 presented in OS17: CP: Anatomy and physiology
Effects of medial gastrocnemius relative fascicle excursion on stance phase plantarflexion work in children with cerebral palsy Teresa [1_TD$IF]Martı´n[4_TD$IF] Lorenzo 1,2,*, Sergio Lerma[5_TD$IF] Lara 1,3 [1_TD$IF] 1
Hospital Infantil Universitario Nin˜o Jesu´s, Madrid, Spain Rey Juan Carlos University, Alcorco´n, Madrid, Spain 3 CSEU La Salle, Universidad Auto´noma de Madrid, Aravaca, Madrid, Spain 2
[(Fig._1)TD$IG]
Introduction: Contraction velocity has been associated to fascicle length (fL) or serial sarcomere number [1]. However, contrary to healthy children (TD), fL has shown no relationship to
Fig. 1. [3_TD$IF]Medial gastrocnemius muscle-tendon unit architecture measurments on ultrasdound image and graphical representation of ankle power during gait. Note that with dorsiflexion the miotendinous junction moves distally, thus tendon excursions are negative. * Corresponding author. E-mail address: [email protected] (T. Martı´n Lorenzo). http://dx.doi.org/10.1016/j.gaitpost.2016.07.189 0966-6362/
isometric power in children with cerebral palsy (CP) [2]. This might be related to inconsistent fL TD vs CP differences [3]. Furthermore, in-series sarcomere addition response to stretch may not occur in CP [4]. Recently, children with CP have shown shorter medial gastrocnemius fascicles undergoing longer relative fascicle excursions (RFE) throughout ROM than TD children, suggesting previously reported overstretched sarcomeres operating at nonoptimal lengths [4,5]. Furthermore, dynamic joint work has shown a strong correlation to muscle volume in CP [6]. Therefore, we believe RFE instead of fL would better correlate with dynamic joint work, or integral of power over time. Research question: Does medial gastrocnemius RFE correlate with plantarflexion work in children with CP? Methods: 18 children with CP (29 legs, 10.74 3.38 years, GMFCS I–III) were assessed. Stance phase plantarflexion work performance was obtained from 3D motion analysis data. Furthermore, 2D ultrasound was used to determine medial gastrocnemius RFE from resting ankle position (RJA) to maximum dorsiflexion (MDF) following ultrasound error reduction techniques [7,8]. Moreover, muscle belly length (bL) and tendon length (tL) were recorded to further inform findings (Fig. 1). Results: Measured RFE was (mean SE) 41.01 3.27%, similar to previous reports of 43.30% [5]. However, RFE was not correlated to plantarflexion work. Further data analysis revealed significant correlations to plantarflexion work. Independent variable
Dependent variable
MDF tL (% tibia length)
Total
MDF fL/bL[2_TD$IF] ratio
Late Stance + Work (J/kg)
MDF tL/fL ratio
Total
MDF fL/bL ratio
Total + Work (J/kg)
tL change (% RJA length)
Total
Work (J/kg)
0.45*
tL change (% RJA length)
Total + Work (J/kg)
0.44*
Work (J/kg) Work (J/kg)
r 0.57* 0.54** 0.52* 0.48*
Discussion: The lack of correlation between RFE and plantarflexion work may be associated to uncontrolled neural mechanisms and muscle structure parameters reflecting in-parallel sarcomeres which also contribute to joint work [6,9]. Muscle volume comprises in-parallel sarcomeres and has been significantly correlated to joint work in both TD and CP to the same extent [6]. Thus, muscle volume may better predict plantarflexion
130
T. Martı´n Lorenzo, S. Lerma Lara / Gait & Posture 49S (2016) 129–130
work independently of neural drive differences. Nevertheless, the ability to perform greater positive or negative work has been significantly associated to tendon excursion, MDF tendon length, MDF fascicle/belly length ratio, and tendon/fascicle length ratio and should thus be taken into account. References [1] Lieber. Muscle Nerve 2000;23:1647–66. [2] Moreau. Gait Posture 2012;35:154–8.
[3] [4] [5] [6] [7] [8] [9]
Barrett. Dev. Med. Child Neurol. 2010;52:794–804. Mathewson. Phys. Med. Rehabil. Clin. N. Am. 2015;26:57–67. Matthiasdottir. Clin. Biomech. 2014;29:458–62. Reid. Disabil. Rehabil. 2014;1–6. Maas. BMC Pediatr. 2012;12:38. Be´nard. Muscle Nerve 2009;52–665. Mockford. Pediatr. Phys. Ther. 2010;22:222–33.