- Email: [email protected]
Reverse shoulder prosthesis—Marker based measurement of the center of rotation localisation
S34
Abstracts / Gait & Posture 36 (2012) S1–S101
phase intergirdle coordination at low walking velocities, while they adopt an anti-phase pattern at higher velocities. The coordination between girdles pertains also to the specific motion of the arms and the legs. Particularly, the inertial effects of the arm swing contribute to a stable walking pattern [3]. However, an individual may be confronted to situations in which a mobilization of the upper limb may be forbidden. Dynamic Pattern Theory offers tools to identify how limbs are coordinated without reference to underlying mechanisms and how coordinative modes spontaneously arise by some quantities, called order parameters [4,5]. Using concepts and tools of from a dynamical approach to coordination, this study aimed to determine the persistence and the strength of the coordination patterns between the pelvic and scapular girdles when no arm swing was allowed during walking and running. Patients/materials and methods: Eight participants were asked to walk or run barefoot on a treadmill under 4 randomized conditions manipulating two factors: Arm (“free swing” vs. “no arm swing”) and Velocity (walking and running). The relative phase value ˚, proved to truthfully measure synchronization [5], was assessed by a Continuous Relative Phase algorithm, using a Hilbert transform [6]. The frequency distribution of ˚ was computed for every participant in each condition. The analysis of these distributions allowed one to determine the coordination patterns adopted most frequently. Data were analyzed using a (2 arm × 2 velocity) ANOVA with repeated measures on both factors with significance level set at p < 0.05. Results: Results showed that an absence of arm swing led to a change from an anti-phase to in-phase pattern and that an increase in velocity in both arm conditions strengthened the adopted pattern more canonical. Moreover, the frequency distribution of ˚ with arm swing proved for some participants to be bimodal. Discussion and conclusion: Bimodality indicates that the prevailing anti-phase pattern was mixed with a noticeable proportion of in-phase pattern. The presence of the in-phase pattern in the natural locomotion with arm swing manifests its persistence and its stability. It perhaps pertains to its prevalence in earlier times in ontogeny as founded in early acquisition of walking [7] or to its presence in atypical locomotion [8]. Although during unrestrained locomotion the anti-phase intergirdle pattern is naturally adopted, it is the fundamentally more stable in-phase pattern that is used under a higher constraint level. Finally, to characterize the adaptive properties of the locomotor system in the face of varying constraints, intergirdle relative timing could be a pertinent descriptor. Disclosure: No significant relationships.
References [1] [2] [3] [4] [5]
Lamoth CJC, et al. Spine 2002. Huang Y, et al. Gait & Posture 2010. Pontzer H, et al. Journal of Experimental Biology 2009. Haken H, et al. Biological Cybernetics 1985. Kelso JAS, et al. Journal of Experimental Psychology: Human Perception and Performance 1992. [6] Pikovsky A, et al. Cambridge: Cambridge University Press; 2001. [7] Ledebt A. Infant Behavior and Development 2000. [8] Wagenaar RC, et al. Journal of Biomechanics 1992.
doi:10.1016/j.gaitpost.2011.10.235 O56 Reverse shoulder prosthesis—Marker based measurement of the center of rotation localisation O. Rettig ∗ , M. Maier Orthopaedic and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
Introduction: A reverse shoulder prosthesis is a surgical option for patients with irreparable cuff tear arthropathy. It allows restoration of active anterior elevation. This improvement of range of motion is attributed to a medialisation and distalisation (with respect to the humerus) of the center of rotation to increase the lever arm of the deltoid muscle. It results in a stronger abduction movement. The purpose of this study is to check the medialisation with marker based motion analysis techniques. Patients/materials and methods: Nine patients were enrolled who underwent reversed arthroplasty (Aequalis Reversed; Tournier, Lyon, France) for massive and irreparable cuff tear arthropathy. All patients were examined before the operation and six months after surgery in a motion analysis study using the Heidelberg Upper Extremity Model (HUX) [1]. This model is based on functional methods to estimate the shoulders’ centers of rotation. In this study its localisation is determined in medio-lateral direction in a thorax based coordinate system. To make pre- and postoperative measurements comparable a static relaxed posture is chosen with arms in a hanging position and the hands laying on the ipsilateral knees. Results: Six patients show a medialisation of shoulders center of rotation about 8.3 ± 2.8 mm (mean/std) postoperative. For the nonaffected contralateral side the difference between the two measurements is −0.3 ± 2.7 mm. Three patients have to be excluded due to a too small preoperative range of shoulder motion (smaller than 30◦ ). Discussion and conclusion: The expected effect of the medialisation of the center of rotation could be checked by marker based motion analysis techniques. The high reproducibility of the method is reached by functional rotation center estimation and the measurement in a relaxed and well repeatable static pose. Unfortunately not all of the patients are able to execute the functional movements for shoulder joint center estimation with sufficient range of motion. The algorithm for center of rotation estimation described in [2] allows a proper estimation based on a smaller range of shoulder motion. The drawback of this algorithm is that it needs three instead of only one marker placed on the humerus [1]. Based on the encouraging results the medialisation is analysed in the ongoing project for more patients. These are measured before and 3/6/12 months after surgery. One interesting question is if the medialisation stays stable or vanishes in a while.
Abstracts / Gait & Posture 36 (2012) S1–S101
Disclosure: No significant relationships. References [1] Rettig, et al. Gait Posture 2009;30(4):469–76. [2] Ehrig, et al. J Biomech 2006;39:2798–809.
doi:10.1016/j.gaitpost.2011.10.236 O57 Cancelled. doi:10.1016/j.gaitpost.2011.10.237 O58 Upper limb movement characteristics in children with unilateral cerebral palsy E. Jaspers 1,∗ , K. Desloovere 1 , K. Klingels 1 , H. Bruyninckx 2 , G. Molenaers 3 , H. Feys 1 1
Department of Rehabilitation Sciences, K.U. Leuven, Leuven, Belgium Department of Mechanical Engineering, K.U. Leuven, Leuven, Belgium 3 Department of Musculoskeletal Sciences, K.U. Leuven, Pellenberg, Belgium
S35
nal rotation (±10◦ , p < 0.001) and less elbow supination (±18◦ , p < 0.0001). While TDC had a neutral wrist position at endpoint, children with UCP used 15–35◦ more wrist flexion to complete all tasks (p < 0.0001). Discussion and conclusion: Significant differences between TDC and children with UCP were found for task duration and maximum velocity. Task-dependent significant differences were also found for endpoint angles of the trunk, scapula, shoulder, elbow and wrist. This study is a first step to gain further insights in UL movement pathology. However, the conversion of 3DMA results into useful information at the level of contributing muscles, bones and joints will be a necessary next step to improve our understanding of UL movement pathology. Disclosure: No significant relationships.
References [1] [2] [3] [4]
Jaspers, et al. Gait Posture 2011;33:279–85. Jaspers, et al. Gait Posture 2011;33:568–75. Cappozzo, et al. Clin Biomech 1995;10:171–8. Wu, et al. J Biomech 2005;38:981–92.
2
Introduction: Children with unilateral cerebral palsy (UCP) have an impaired ability to reach, grasp, release and manipulate objects, which impacts on many daily activities. Adequate treatment planning is crucial to improve these children’s function and independence in daily life. Three-dimensional movement analysis (3DMA) allows the objective quantification of upper limb (UL) motor performance by means of spatiotemporal and kinematic parameters. The aim of this study was to identify distinct UL movement characteristics in children with UCP compared to typically developing children (TDC) using 3DMA. Patients/materials and methods: Twenty children with congenital UCP (10.9 ± 2.9 ys) and 20 individually age-matched TDC (10.9 ± 3.0 ys) with no history of musculoskeletal or neurological problems were recruited. Children with UCP had to be able to actively grasp and hold an object weakly and were excluded in case of UL surgery or recent BTX-injections. They were sampled across the first 3 levels of the MACS (level I: n = 4; level II: n = 15; level III: n = 1). UL limb task performance was assessed during reach forward (RF), reach to grasp a vertically oriented cylinder (RGV) and hand to mouth (HTM). During testing, children were seated in a custom-made chair with individually adjustable sitting position and reaching distance/height. All tasks were executed with the non-preferred (affected or non-dominant) arm at self-selected speed. Seventeen retro-reflective markers were placed over the trunk, scapula, humerus, forearm and hand in clusters of 3–4 markers [1,2]. Anatomical landmarks were palpated and digitized during static trials [3]. Marker tracking was done with the Vicon MX-system (Oxford Metrics, UK), data was further processed with Matlab® (www.bodymech.be). Kinematics were calculated following the ISB-guidelines [4]. Spatiotemporal (task duration, maximum hand velocity) and kinematic (endpoint joint angles) parameters were compared between both groups using an unpaired t-test. Statistical analysis was done with SAS E-Guide (SAS Institute, Inc., Cary, NC), significance was set at 0.05. Results: Children with UCP had significantly longer task durations for the 3 tasks and lower maximum velocities during RGV and HTM (Fig. 1). Children with UCP used more trunk flexion (±5◦ , p < 0.05) and less elbow extension (>20◦ , p < 0.0001) during RF and RGV. RGV also resulted in less shoulder elevation (± 7◦ , p < 0.001) and elbow supination (>30◦ , p < 0.0001). During HTM, children with UCP used more scapula protraction (±5◦ , p < 0.05), shoulder exter-
doi:10.1016/j.gaitpost.2011.10.238 O59 A protocol to analyze 3D scapulo-humeral motion in children M. Lempereur 1,∗ , S. Brochard 2 , O. Rémy-Néris 2 1 2
LaTIM INSERM U650, Brest, France CHRU de Brest, Brest, France
Introduction: Upper-limb motion analysis using external markers in children is a recently growing field. Most studies have evaluated shoulder motion as the thoraco-humeral joint [1] and not as the thoraco-scapulo-humeral complex. However, an accurate 3D analysis of the gleno-humeral motion would be relevant for many situations in neurology or orthopaedic diseases. In order to obtain a detailed analysis of the shoulder, we developed a protocol based on an acromion marker cluster [2], the determination of the gleno-humeral rotation center using functional method and different Euler sequences. Patients/materials and methods: 10 typically developing (TD) and 10 hemiplegic cerebral palsied (HCP) children were included. The HCP children had mild to moderate hemiplegia. The kinematics was recorded using the optoelectronic tracking system Vicon. Humeral and thoracic markers were placed as recommended by the International Society of Biomechanics [3]. A cluster of four markers was fixed on the upper arm. An acromion marker cluster was added on the acromion flat surface. Each child performed 3 trials of 6 tasks: full flexion, full abduction, horizontal abduction, hand to head, hand to controlateral shoulder and hand to ipsilateral back pocket. Moreover, 3 flexions/extensions, 3 abductions/adductions and 3 circumductions were performed to calculate the gleno-humeral rotation center [4]. The scapular orientations relative to the thorax (ST) were described using the YXZ Euler sequence. Humeral motions relative to the thorax (TH) and relative to the scapula (GH) were computed with the XZY Euler sequence. Inter-trial reliability was assessed using the coefficient of multiple correlations (CMC). The comparison between the mean data of the TD and HCP children at 0%, 100% and the range of motion was carried out using a paired Wilcoxon rank test. Results: The overall CMC was good to excellent for the TH joint (0.90 in TD, 0.87 in HCP), moderate for the ST joint (0.79 in TD and HCP) and good for the GH joint (0.82 in TD and HCP). Significant differences were found for the TH, ST and GH joint kinematics in the 3 planes of motion depending on the tasks. At TH joint, the resting
Abstracts / Gait & Posture 36 (2012) S1–S101
phase intergirdle coordination at low walking velocities, while they adopt an anti-phase pattern at higher velocities. The coordination between girdles pertains also to the specific motion of the arms and the legs. Particularly, the inertial effects of the arm swing contribute to a stable walking pattern [3]. However, an individual may be confronted to situations in which a mobilization of the upper limb may be forbidden. Dynamic Pattern Theory offers tools to identify how limbs are coordinated without reference to underlying mechanisms and how coordinative modes spontaneously arise by some quantities, called order parameters [4,5]. Using concepts and tools of from a dynamical approach to coordination, this study aimed to determine the persistence and the strength of the coordination patterns between the pelvic and scapular girdles when no arm swing was allowed during walking and running. Patients/materials and methods: Eight participants were asked to walk or run barefoot on a treadmill under 4 randomized conditions manipulating two factors: Arm (“free swing” vs. “no arm swing”) and Velocity (walking and running). The relative phase value ˚, proved to truthfully measure synchronization [5], was assessed by a Continuous Relative Phase algorithm, using a Hilbert transform [6]. The frequency distribution of ˚ was computed for every participant in each condition. The analysis of these distributions allowed one to determine the coordination patterns adopted most frequently. Data were analyzed using a (2 arm × 2 velocity) ANOVA with repeated measures on both factors with significance level set at p < 0.05. Results: Results showed that an absence of arm swing led to a change from an anti-phase to in-phase pattern and that an increase in velocity in both arm conditions strengthened the adopted pattern more canonical. Moreover, the frequency distribution of ˚ with arm swing proved for some participants to be bimodal. Discussion and conclusion: Bimodality indicates that the prevailing anti-phase pattern was mixed with a noticeable proportion of in-phase pattern. The presence of the in-phase pattern in the natural locomotion with arm swing manifests its persistence and its stability. It perhaps pertains to its prevalence in earlier times in ontogeny as founded in early acquisition of walking [7] or to its presence in atypical locomotion [8]. Although during unrestrained locomotion the anti-phase intergirdle pattern is naturally adopted, it is the fundamentally more stable in-phase pattern that is used under a higher constraint level. Finally, to characterize the adaptive properties of the locomotor system in the face of varying constraints, intergirdle relative timing could be a pertinent descriptor. Disclosure: No significant relationships.
References [1] [2] [3] [4] [5]
Lamoth CJC, et al. Spine 2002. Huang Y, et al. Gait & Posture 2010. Pontzer H, et al. Journal of Experimental Biology 2009. Haken H, et al. Biological Cybernetics 1985. Kelso JAS, et al. Journal of Experimental Psychology: Human Perception and Performance 1992. [6] Pikovsky A, et al. Cambridge: Cambridge University Press; 2001. [7] Ledebt A. Infant Behavior and Development 2000. [8] Wagenaar RC, et al. Journal of Biomechanics 1992.
doi:10.1016/j.gaitpost.2011.10.235 O56 Reverse shoulder prosthesis—Marker based measurement of the center of rotation localisation O. Rettig ∗ , M. Maier Orthopaedic and Trauma Surgery, Heidelberg University Hospital, Heidelberg, Germany
Introduction: A reverse shoulder prosthesis is a surgical option for patients with irreparable cuff tear arthropathy. It allows restoration of active anterior elevation. This improvement of range of motion is attributed to a medialisation and distalisation (with respect to the humerus) of the center of rotation to increase the lever arm of the deltoid muscle. It results in a stronger abduction movement. The purpose of this study is to check the medialisation with marker based motion analysis techniques. Patients/materials and methods: Nine patients were enrolled who underwent reversed arthroplasty (Aequalis Reversed; Tournier, Lyon, France) for massive and irreparable cuff tear arthropathy. All patients were examined before the operation and six months after surgery in a motion analysis study using the Heidelberg Upper Extremity Model (HUX) [1]. This model is based on functional methods to estimate the shoulders’ centers of rotation. In this study its localisation is determined in medio-lateral direction in a thorax based coordinate system. To make pre- and postoperative measurements comparable a static relaxed posture is chosen with arms in a hanging position and the hands laying on the ipsilateral knees. Results: Six patients show a medialisation of shoulders center of rotation about 8.3 ± 2.8 mm (mean/std) postoperative. For the nonaffected contralateral side the difference between the two measurements is −0.3 ± 2.7 mm. Three patients have to be excluded due to a too small preoperative range of shoulder motion (smaller than 30◦ ). Discussion and conclusion: The expected effect of the medialisation of the center of rotation could be checked by marker based motion analysis techniques. The high reproducibility of the method is reached by functional rotation center estimation and the measurement in a relaxed and well repeatable static pose. Unfortunately not all of the patients are able to execute the functional movements for shoulder joint center estimation with sufficient range of motion. The algorithm for center of rotation estimation described in [2] allows a proper estimation based on a smaller range of shoulder motion. The drawback of this algorithm is that it needs three instead of only one marker placed on the humerus [1]. Based on the encouraging results the medialisation is analysed in the ongoing project for more patients. These are measured before and 3/6/12 months after surgery. One interesting question is if the medialisation stays stable or vanishes in a while.
Abstracts / Gait & Posture 36 (2012) S1–S101
Disclosure: No significant relationships. References [1] Rettig, et al. Gait Posture 2009;30(4):469–76. [2] Ehrig, et al. J Biomech 2006;39:2798–809.
doi:10.1016/j.gaitpost.2011.10.236 O57 Cancelled. doi:10.1016/j.gaitpost.2011.10.237 O58 Upper limb movement characteristics in children with unilateral cerebral palsy E. Jaspers 1,∗ , K. Desloovere 1 , K. Klingels 1 , H. Bruyninckx 2 , G. Molenaers 3 , H. Feys 1 1
Department of Rehabilitation Sciences, K.U. Leuven, Leuven, Belgium Department of Mechanical Engineering, K.U. Leuven, Leuven, Belgium 3 Department of Musculoskeletal Sciences, K.U. Leuven, Pellenberg, Belgium
S35
nal rotation (±10◦ , p < 0.001) and less elbow supination (±18◦ , p < 0.0001). While TDC had a neutral wrist position at endpoint, children with UCP used 15–35◦ more wrist flexion to complete all tasks (p < 0.0001). Discussion and conclusion: Significant differences between TDC and children with UCP were found for task duration and maximum velocity. Task-dependent significant differences were also found for endpoint angles of the trunk, scapula, shoulder, elbow and wrist. This study is a first step to gain further insights in UL movement pathology. However, the conversion of 3DMA results into useful information at the level of contributing muscles, bones and joints will be a necessary next step to improve our understanding of UL movement pathology. Disclosure: No significant relationships.
References [1] [2] [3] [4]
Jaspers, et al. Gait Posture 2011;33:279–85. Jaspers, et al. Gait Posture 2011;33:568–75. Cappozzo, et al. Clin Biomech 1995;10:171–8. Wu, et al. J Biomech 2005;38:981–92.
2
Introduction: Children with unilateral cerebral palsy (UCP) have an impaired ability to reach, grasp, release and manipulate objects, which impacts on many daily activities. Adequate treatment planning is crucial to improve these children’s function and independence in daily life. Three-dimensional movement analysis (3DMA) allows the objective quantification of upper limb (UL) motor performance by means of spatiotemporal and kinematic parameters. The aim of this study was to identify distinct UL movement characteristics in children with UCP compared to typically developing children (TDC) using 3DMA. Patients/materials and methods: Twenty children with congenital UCP (10.9 ± 2.9 ys) and 20 individually age-matched TDC (10.9 ± 3.0 ys) with no history of musculoskeletal or neurological problems were recruited. Children with UCP had to be able to actively grasp and hold an object weakly and were excluded in case of UL surgery or recent BTX-injections. They were sampled across the first 3 levels of the MACS (level I: n = 4; level II: n = 15; level III: n = 1). UL limb task performance was assessed during reach forward (RF), reach to grasp a vertically oriented cylinder (RGV) and hand to mouth (HTM). During testing, children were seated in a custom-made chair with individually adjustable sitting position and reaching distance/height. All tasks were executed with the non-preferred (affected or non-dominant) arm at self-selected speed. Seventeen retro-reflective markers were placed over the trunk, scapula, humerus, forearm and hand in clusters of 3–4 markers [1,2]. Anatomical landmarks were palpated and digitized during static trials [3]. Marker tracking was done with the Vicon MX-system (Oxford Metrics, UK), data was further processed with Matlab® (www.bodymech.be). Kinematics were calculated following the ISB-guidelines [4]. Spatiotemporal (task duration, maximum hand velocity) and kinematic (endpoint joint angles) parameters were compared between both groups using an unpaired t-test. Statistical analysis was done with SAS E-Guide (SAS Institute, Inc., Cary, NC), significance was set at 0.05. Results: Children with UCP had significantly longer task durations for the 3 tasks and lower maximum velocities during RGV and HTM (Fig. 1). Children with UCP used more trunk flexion (±5◦ , p < 0.05) and less elbow extension (>20◦ , p < 0.0001) during RF and RGV. RGV also resulted in less shoulder elevation (± 7◦ , p < 0.001) and elbow supination (>30◦ , p < 0.0001). During HTM, children with UCP used more scapula protraction (±5◦ , p < 0.05), shoulder exter-
doi:10.1016/j.gaitpost.2011.10.238 O59 A protocol to analyze 3D scapulo-humeral motion in children M. Lempereur 1,∗ , S. Brochard 2 , O. Rémy-Néris 2 1 2
LaTIM INSERM U650, Brest, France CHRU de Brest, Brest, France
Introduction: Upper-limb motion analysis using external markers in children is a recently growing field. Most studies have evaluated shoulder motion as the thoraco-humeral joint [1] and not as the thoraco-scapulo-humeral complex. However, an accurate 3D analysis of the gleno-humeral motion would be relevant for many situations in neurology or orthopaedic diseases. In order to obtain a detailed analysis of the shoulder, we developed a protocol based on an acromion marker cluster [2], the determination of the gleno-humeral rotation center using functional method and different Euler sequences. Patients/materials and methods: 10 typically developing (TD) and 10 hemiplegic cerebral palsied (HCP) children were included. The HCP children had mild to moderate hemiplegia. The kinematics was recorded using the optoelectronic tracking system Vicon. Humeral and thoracic markers were placed as recommended by the International Society of Biomechanics [3]. A cluster of four markers was fixed on the upper arm. An acromion marker cluster was added on the acromion flat surface. Each child performed 3 trials of 6 tasks: full flexion, full abduction, horizontal abduction, hand to head, hand to controlateral shoulder and hand to ipsilateral back pocket. Moreover, 3 flexions/extensions, 3 abductions/adductions and 3 circumductions were performed to calculate the gleno-humeral rotation center [4]. The scapular orientations relative to the thorax (ST) were described using the YXZ Euler sequence. Humeral motions relative to the thorax (TH) and relative to the scapula (GH) were computed with the XZY Euler sequence. Inter-trial reliability was assessed using the coefficient of multiple correlations (CMC). The comparison between the mean data of the TD and HCP children at 0%, 100% and the range of motion was carried out using a paired Wilcoxon rank test. Results: The overall CMC was good to excellent for the TH joint (0.90 in TD, 0.87 in HCP), moderate for the ST joint (0.79 in TD and HCP) and good for the GH joint (0.82 in TD and HCP). Significant differences were found for the TH, ST and GH joint kinematics in the 3 planes of motion depending on the tasks. At TH joint, the resting