Background: This study evaluated a patellar tendon shortening (PTS) surgical procedure that uses an overlapping repair combined with an additional Tycron non-absorbable suture to support the shortening in children with Cerebral Palsy (CP). This study aimed to outline this surgical technique and to evaluate its effectiveness in restoring the knee extensor mechanism. Methods: The sagittal plane lower limb kinematics, peak knee extensor moment, gait deviation index (GDI), localised movement deviation profile (MDP), temporospatial parameters, passive knee extension ROM, quadriceps lag, and knee extensor strength were calculated pre- and postoperatively. To determine significant differences a robust linear regression model with high breakdown point and high efficiency was fitted to the data. Results: In this retrospective cohort study, a total of 41 patients with CP who were treated with unilateral or bilateral PTS in isolation or as part of single event multilevel surgery (SEMLS), with a mean age of 11.1 years were included. The knee extension angle improved at initial contact (p < 0.0001), and during stance phase (p < 0.0001). The peak internal knee extensor moment decreased during early (p = 0.0014) and late stance phase (p < 0.0001). The quadriceps lag decreased (p < 0.0001) and knee extensor strength increased (p < 0.0001). The GDI improved (p < 0.0001), as well as the localised MDP for sagittal angles (p <0.0001) and moments (p = 0.0001). Walking speed (p = 1.0) remained unchanged, but the cadence decreased (p = 0.024) and step length increased (p = 0.0001). Conclusions: The knee extension angle and moment during stance phase improved significantly. The children with CP in this study showed improvements in knee extensor strength and quadriceps lag. Thereby it can be concluded that the PTS procedure was able to restore the knee extensor mechanism effectively.

Aims:The aim of this study was to identify the number of ambulant children with cerebral palsy (CP) who are eligible for single-event multilevel surgery (SEMLS) in the UK, to explore regional variations in care and estimate the outcomes over a two-year period. Methods:This was a prospective, comprehensive cohort study, to evaluate current surgical practice in ambulant patients with bilateral CP. The case mix, intervention variables, and clinical outcomes, including patient-based outcomes, were recorded in a consented sub-group. Data from children who did not undergo surgery within the time of the study were used for comparison. Results:A total of 203 children were enrolled, over a period of 52 months. There were 138 males and 65 females, with a mean age of 12.6 years (5.4 to 18.1). A total of 188 children met the inclusion criteria. At the time of enrolment, the surgical and non-surgical groups had similar clinical characteristics. Of the 139 children who underwent SEMLS, the mean was 5.3 procedures (2 to 12) per patient. There was considerable variation in the procedures undertaken at the different sites. Outcome measures were available in a subgroup of children. Complications were recorded in 25 children (18%). At two years following SEMLS, the Gait Profile Score improved beyond the minimal clinically important difference, as did the parental perception of motor function (Gait Outcomes Assessment List questionnaire). There was some indication of improvement in motor function (Functional Mobility Scale). While the non-surgical group was small, there was a general decline in gait over the same period in this group. Conclusion:National data illustrating the practice of SEMLS across the UK, which is useful for clinicians to inform discussions with patients, were collected in this study. While the natural history of these children is of gradual functional decline, there was a clear signal of the effectiveness of SEMLS. Consensus to standardize clinical practice is needed, as are further studies to assess the outcomes accurately.

Background Children with cerebral palsy (CP) regularly fall over and this has negative effects on their physical and psychosocial wellbeing (e.g., reduced activity participation). However, the reasons for falls are not well understood. The way in which children negotiate challenging walking environments (e.g., uneven surfaces), may reveal more about how falls occur as these environments require gait modifications to maintain stability. Stability in challenging walking environments has been explored for children with CP; however, it remains unclear how these lead to falls. Research question Do challenging walking environments that mimic those faced in the real-world, contribute to increased fall occurrence and fall risk in children with CP? Methods Five databases were searched, and 1386 records screened to include ambulatory children with CP, aged 5-18 years old, investigating dynamic walking in challenging environments, with outcomes of fall occurrence or fall risk. The full protocol for this review was registered on PROSPERO (CRD42021290456). Results Sixteen studies met the inclusion criteria. One study reported occurrence of stumbles, two reported no falls. Fifteen studies identified gait alterations used by children with CP in challenging environments. Twenty-four gait characteristics were identified to be indicative of cautious walking strategies and seven gait characteristics identified to increase fall risk, suggesting a potential link. However, limited evidence exists as to whether this reflects falls faced in the real-world. Significance Investigations into stability over challenging walking environments for children with CP are lacking any measures of fall occurrence. Investigations into the mechanisms that may contribute to high fall risk, or fall avoidance when negotiating obstacles, uneven surfaces, steep declines and stairs may reveal further causes of real-world falls, and in doing so inform future fall prevention techniques. Finally, understanding the multifaceted causes of falls in real-world challenging environments from the perspectives of children with CP is key for future research.

Children with cerebral palsy (CP) exhibit head instability during simple overground walking, which may comprise sensory input and reduce stepping accuracy. Investigations of head stability during more challenging tasks, where fall risk may be increased, are limited. This study explored differences in head stability between ambulatory children with hemiplegic CP (N = 9) and diplegia (N = 9) (GMFCS I and II) and typically developing (TD) children (N = 8) during a targeted stepping task. All children completed five trials stepping into two successive rectangular floor-based targets whilst walking along an 8 m walkway. Three-dimensional motion capture enabled calculation of head stability and foot placement within and before each target. A two-way mixed-design ANOVA compared differences between all groups and target approach. Children with diplegic CP showed greater sagittal, frontal, and resultant head-to-laboratory and head-to-trunk head instability compared to children with hemiplegic CP and TD children. Anteroposterior foot placement error was significantly greater in children with hemiplegic CP (8.5 ± 5.0 cm) compared to TD children (3.8 ± 1.5 cm). Group differences in head instability were not consistent with group differences in foot placement error. To better understand how head instability might affect fall risk in children with CP, more challenging environments should be tested in future.

Children with cerebral palsy (CwCP) experience regular falls [1] but their lived experiences of how falls occur in the real-world are unknown. Understanding real-world causes of falls by listening to perspectives of children and parents is vital, since typical walking analyses are carried out over level-ground and therefore overlooks everyday challenges to balance [2]. Walk-along interviews can generate rich insights into children's everyday life by discussing experiences while walking [3]. This abstract presents findings from 'The Walk-Along Project', a novel qualitative investigation using walk-along interviews to explore lived experiences of CwCP. The Walk-Along Project aimed to determine the challenging walking environments (e.g. uneven surfaces) that increase fall-risk. What types of challenging environments affect fall-risk in CwCP, based on their lived experiences? Twelve CwCP (GMFCS I to III, 6 diplegia, 6 hemiplegia, 12±3 years old) and their parents participated in an outdoor walk-along interview lasting approximately 25 minutes. During each walk-along interview participants discussed previous fall experiences and everyday 'challenging' environments (likely to cause a fall) that they commonly encounter. Chest-mounted cameras (Kaiser Baas X450) and clip on microphones (RODE GO II) captured walking environments and conversations. Data from microphones were matched to video footage, manually transcribed and analysed in NVivo using interpretive description[4]. Environments that could or have previously caused a fall were identified by CwCP and photographed during walk-along interviews (Fig. 1). Any uneven surface that could cause a trip or balance disturbance was suggested as challenging, such as tactile paving: "I'd probably trip over it because it is bumpy" (child, aged 13) Unseen grass potholes were reported to cause most falls based on past experiences. Falls were also more likely when combined with sensory distractions (e.g. seeing/hearing nearby people/friends): "So like if I am walking in this direction and am looking at [people playing nearby] football I could go like that…[demonstrates trailing foot tripping on a raised grid]" (child, aged 16) Download : Download high-res image (167KB)Download : Download full-size image Children described things they do to reduce fall-risk, including being careful, avoiding places or walking slower: "I would just go slow on a grass surface and hope that I don't fall" (Child, aged 8) Younger children evidenced receiving more parental intervention when walking in challenging environments (e.g. "watch your step"). In comparison, older children reported having better awareness of what could cause a fall compared to when they were younger. The Walk-Along Project provides novel insight beyond what is currently known about the types of challenging environments that increase fall-risk in CwCP. Both environmental (uneven surfaces) and sensory (everyday distractions) challenges contribute heavily to daily fall occurrence, which is not considered in existing assessments of CwCP [2]. Future work should consider these interacting factors when trying to determine CwCP at high fall-risk and in the design of fall prevention programmes.

Children with cerebral palsy (CwCP) regularly fall (35% fall daily), yet reasons for their falls are not well understood [1]. Stability and changes in walking behaviour of CwCP when negotiating challenging walking environments (e.g. uneven surfaces) have been accurately measured in laboratory settings [2], however these have not captured the real-world fall-risk that CwCP face daily. Walk-along interviews are a useful approach to capture the meaningful lived experiences of children whilst they are walking outside in challenging environments [3,4]. Previously, we co-designed a novel walk-along interview protocol by engaging with CwCP[5]. Real-world insights gathered from these walk-along interviews could enable us to design bespoke research protocols that explore the mechanisms of daily falls in CwCP. How do lived experiences of CwCP inform the development of a bespoke lab-based protocol to investigate the mechanisms of falls? Twelve CwCP (GMFCS I to III, 6 diplegia, 6 hemiplegia, 12±3 years old) and their parents took part in tailored walk-along interviews in which they discussed everyday fall experiences based on environments encountered on an outdoor walk. Chest-mounted cameras (Kaiser Baas X450) and wireless microphones (RODE GO II) captured environments and conversations. Walk-along interviews were analysed in NVivo using interpretive description[6]. Key insights from interviews (e.g. previous fall experiences) were used to determine the types of environments to be included in a bespoke walking protocol for assessing mechanisms of falls. Four CwCP and their parents were consulted about the findings from walk-along interviews to support protocol design. Walk-along interviews revealed that falls most often result when environmental challenges ("bumpy" surfaces) and sensory challenges (being "distracted" or "not looking") are present together. Discussing previous falls or trips (Fig. 1) with CwCP and their parents informed the design of a bespoke walkway to investigate mechanisms of falls in challenging environments. The walkway includes common environmental challenges that cause falls (grass potholes and uneven pavements). To emulate the sensory challenges reported during walk-along interviews, randomly selected trials over the bespoke walkway will include a virtual distraction imitating noises and images of a busy street. Consultations with CwCP suggested these virtual distractions should include dogs barking and cars driving on busy roads. Download : Download high-res image (87KB)Download : Download full-size image We have designed a bespoke protocol that replicates the challenging environmental features and distractions faced daily by CwCP. Our protocol is unique because it was informed by the lived experiences of CwCP and their parents during novel walk-along interviews. We will next investigate, using 3D motion capture, potential indicators of high fall-risk (e.g. foot placement, decreased margins of stability) in CwCP compared to typically developing children when negotiating the bespoke walkway with and without distractions. With our protocol, we hope to identify fall-risk behaviours when CwCP negotiate replica real-world environments, to inform future fall prevention programmes.

Purpose The effective mechanical advantage (EMA) of the plantarflexor muscles is important for gait function and is likely different from typical in equinus gait. However, this has never been quantified for children who idiopathically toe-walk (ITW), despite being routinely altered through clinical intervention. Methods This study quantified the Achilles tendon and ground reaction force (GRF) moment arms, and the plantarflexor EMA of 5 children who ITW and 14 typically developing (TD) children, whilst walking on an instrumented treadmill. Results There was no difference in the Achilles tendon moment arm length throughout stance between groups (p > 0.05). Children who ITW had a significantly greater GRF moment arm length in early stance (20-24% p = 0.001), but a significantly shorter GRF moment arm length during propulsion (68-74% of stance; p = 0.013) than TD children. Therefore, children who ITW had a greater plantarflexor EMA than TD children when active plantarflexion moments were being generated (60-70% of stance; p = 0.007). Consequently, it was estimated that children who ITW required 30% less plantarflexor muscle force for propulsion. Conclusion Clinical decision making should fully consider that interventions which aim to restore a typical heel-toe gait pattern risk compromising this advantageous leverage and thus, may increase the strength requirements for gait.

Experimental PhysiologyVolume 107, Issue 12 p. 1525-1526 REPLY Reply to Veerkamp et al.: Comments on Harkness-Armstrong et al. (2021) This article relates to: In vivo operating lengths of the gastrocnemius muscle during gait in children who idiopathically toe-walk Carla Harkness-Armstrong, Constantinos Maganaris, Roger Walton, David M. Wright, Alfie Bass, Vasilios Baltzopoulos, Thomas D. O'Brien, Volume 106Issue 8Experimental Physiology pages: 1806-1813 First Published online: July 6, 2021 Comments on Harkness-Armstrong et al. (2021) ‘In vivo operating lengths of the gastrocnemius muscle during gait in children who idiopathically toe-walk’ Kirsten Veerkamp, Marjolein M. van der Krogt, Niels F. J. Waterval, Thomas Geijtenbeek, Henry P. J. Walsh, Jaap Harlaar, Annemieke I. Buizer, David G. Lloyd, Christopher P. Carty, Volume 107Issue 12Experimental Physiology pages: 1521-1524 First Published online: November 9, 2022 Carla Harkness-Armstrong, Corresponding Author Carla Harkness-Armstrong [email protected] Research Centre for Physical Activity, Health, and Disease, Division of Sport, Health and Exercise Sciences, Brunel University London, London, UK Correspondence Carla Harkness-Armstrong, Research Centre for Physical Activity, Health, and Disease, Division of Sport, Health and Exercise Sciences, Brunel University London, London, UK. Email: [email protected]Search for more papers by this authorConstantinos N. Maganaris, Constantinos N. Maganaris Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UKSearch for more papers by this authorRoger Walton, Roger Walton Alder Hey Children's NHS Foundation Trust, Liverpool, UKSearch for more papers by this authorDavid M. Wright, David M. Wright Alder Hey Children's NHS Foundation Trust, Liverpool, UKSearch for more papers by this authorAlfie Bass, Alfie Bass Alder Hey Children's NHS Foundation Trust, Liverpool, UKSearch for more papers by this authorVasilios Baltzopoulos, Vasilios Baltzopoulos Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UKSearch for more papers by this authorThomas D. O'Brien, Thomas D. O'Brien Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UKSearch for more papers by this author Carla Harkness-Armstrong, Corresponding Author Carla Harkness-Armstrong [email protected] Research Centre for Physical Activity, Health, and Disease, Division of Sport, Health and Exercise Sciences, Brunel University London, London, UK Correspondence Carla Harkness-Armstrong, Research Centre for Physical Activity, Health, and Disease, Division of Sport, Health and Exercise Sciences, Brunel University London, London, UK. Email: [email protected]Search for more papers by this authorConstantinos N. Maganaris, Constantinos N. Maganaris Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UKSearch for more papers by this authorRoger Walton, Roger Walton Alder Hey Children's NHS Foundation Trust, Liverpool, UKSearch for more papers by this authorDavid M. Wright, David M. Wright Alder Hey Children's NHS Foundation Trust, Liverpool, UKSearch for more papers by this authorAlfie Bass, Alfie Bass Alder Hey Children's NHS Foundation Trust, Liverpool, UKSearch for more papers by this authorVasilios Baltzopoulos, Vasilios Baltzopoulos Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UKSearch for more papers by this authorThomas D. O'Brien, Thomas D. O'Brien Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UKSearch for more papers by this author First published: 21 November 2022 https://doi.org/10.1113/EP090898 Handling Editor: Julien Ochala Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume107, Issue121 December 2022Pages 1525-1526 RelatedInformation

Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles and thus, at shorter muscle-tendon unit (MTU) lengths than typically developing (TD) children. Therefore, it is often assumed that habitual use of the gastrocnemius muscle in this way will cause remodelling of the muscle-tendon architecture compared to TD children. However, the gastrocnemius muscle architecture of children who ITW has never been measured. It is essential that we gain a better understanding of these muscle-tendon properties, to ensure that appropriate clinical interventions can be provided for these children. Five children who ITW (age 8 ± 2 years) and 14 TD children (age 10 ± 2 years) participated in this study. Ultrasound was combined with isokinetic dynamometry and surface electromyography, to measure muscle architecture at common positions and passive lengthening properties of the gastrocnemius muscle and tendon across full range of motion. Regardless of which common condition groups were compared under, both the absolute and normalised to MTU muscle belly and fascicle lengths were always longer, and the Achilles tendon length was always shorter in children who ITW than TD children (p < 0.05; large effect sizes). The passive lengthening properties of the muscle and tendon were not different between groups (p > 0.05); however, passive joint stiffness was greater in children who ITW at maximum dorsiflexion (p = 0.001) and at a joint moment common to all participants (p = 0.029). Consequently, the findings of this pilot study indicate a remodelling of the relative MTU that does not support the concept that children who ITW commonly experience muscle shortening. Therefore, greater consideration of the muscle and tendon properties are required when prescribing clinical interventions that aim to lengthen the MTU, and treatments may be better targeted at the Achilles tendon in children who ITW.

New Findings What is the central question of this study? What are the in vivo operating lengths of the gastrocnemius muscle in children who idiopathically toe-walk? What is the main finding and its importance? Children who idiopathically toe-walk operate at more plantarflexed positions but at longer fascicle lengths than typically developing children during gait. However, these ranges utilised during gait correspond to where children who idiopathically toe-walk are optimally strong. This should be considered when prescribing clinical treatments to restore typical gait. Children who idiopathically toe-walk (ITW) habitually operate at greater plantarflexion angles than typically developing (TD) children, which might result in shorter, sub-optimal gastrocnemius fascicle lengths. However, currently no experimental evidence exists to substantiate this notion. Five children who ITW and 14 TD children completed a gait analysis, whilst gastrocnemius fascicle behaviour was simultaneously quantified using ultrasound. The moment-angle (hip, knee and ankle) and moment-length (gastrocnemius) relationships were determined from isometric maximum voluntary contractions (MVC) on an isokinetic dynamometer combined with ultrasound. During gait, children who ITW operated at more plantarflexed angles (Delta = 20 degrees; P = 0.013) and longer muscle fascicle lengths (Delta = 12 mm; P = 0.008) than TD children. During MVC, no differences in the peak moment of any joint were found. However, peak plantarflexor moment occurred at significantly more plantarflexed angles (-16 vs. 1 degrees; P = 0.010) and at longer muscle fascicle lengths (44 vs. 37 mm; P = 0.001) in children who ITW than TD children. Observed alterations in the moment-angle and moment-length relationships of children who ITW coincided with the ranges used during gait. Therefore, the gastrocnemius muscle in children who ITW operates close to the peak of the force-length relationship, similarly to TD children. Thus, this study indicates that idiopathic toe-walking is truly an ankle joint pathology, and children who ITW present with substantial alterations in the gastrocnemius muscle functional properties, which appear well adapted to the characteristic demands of equinus gait. These findings should be considered when prescribing clinical treatments to restore typical gait.

The objective of the present study was to highlight the role of head stabilization and to analyze multisegment head-trunk coordination during gait in children with cerebral palsy (CP).Postural control was measured and compared in a group of 16 CP subjects and a control group of 16 healthy subjects. The subjects had to walk along an out-and-back course at their freely chosen gait speed. For each gait cycle, motion analysis techniques were used to calculate the amplitude of the head angle (relative to the trunk) in the sagittal and frontal planes.Kinematic analysis revealed a number of significant intergroup differences, with a more pronounced variation in the head angle (relative to the trunk) in the CP group than in the control group. There were no significant intergroup differences in terms of the angular amplitude of the head in the sagittal plane.The greater variability of the head angle in the frontal plane in the CP subjects might reflect the presence of greater head roll as a compensatory strategy. These finding suggest that the clinical evaluation of posture during gait in children with CP should be reconsidered.L'objectif de cette étude était de mettre en évidence le rôle éventuel de la stabilisation de la tête et d'analyser les coordinations multisegmentaires entre la tête et le tronc lors de la marche chez des enfants atteints de paralysie cérébrale (PC).Un groupe de 16 sujets PC a été comparé à un groupe témoin de 16 sujets sains afin de quantifier d'éventuelles stratégies différentes dans le contrôle postural dans une tâche de locomotion. Les sujets devaient réaliser en marchant à vitesse spontanée des aller-retours sur une distance de 10 m. Les méthodes d'analyse du mouvement ont permis de calculer pour chaque cycle de marche les amplitudes maximales et minimales des angles de la tête par rapport au tronc dans les plans sagittal et frontal.L'analyse des données cinématiques montre des différences significatives avec notamment une variabilité de l'angle de la tête par rapport au tronc plus marquée chez les sujets PC dans le plan frontal. On ne constate aucune différence significative au niveau des amplitudes angulaires de la tête dans le plan sagittal.Les deux groupes stabilisent la tête dans le plan sagittal. Dans le plan frontal, la variabilité des données traduirait la présence d'un roulis plus marqué chez les sujets PC leur permettant probablement de développer des stratégies de compensation afin d'atténuer les conséquences de leur atteinte. Cela permettrait de reconsidérer cliniquement l'organisation posturale globale des enfants PC dans la production de la marche.

Little is known about the effects of current PAH therapies and receptor tyrosine kinase inhibitors on heart remodeling. We sought to investigate the effects of the multikinase inhibitors sunitinib (PDGFR-, VEGFR- and KIT-inhibitor) and sorafenib (raf1/b-, VEGFR-, PDGFR-inhibitor) on pressure overload induced right ventricular (RV) remodeling.We investigated the effects of the kinase inhibitors on hemodynamics and remodeling in rats subjected either to monocrotaline (MCT)-induced PH or to surgical pulmonary artery banding (PAB). MCT rats were treated from days 21 to 35 with either vehicle, sunitinib (1 mg/kg, 5 mg/kg and 10 mg/kg/day) or sorafenib (10 mg/kg/day). PAB rats were treated with vehicle, sunitinib (10 mg/kg/day) or sorafenib (10 mg/kg/day) from days 7 to 21. RV function and remodeling were determined using echocardiography, invasive hemodynamic measurement and histomorphometry.Treatment with both sorafenib and sunitinib decreased right ventricular systolic pressure, pulmonary vascular remodeling, RV hypertrophy and fibrosis in MCT rats. This was associated with an improvement of RV function. Importantly, after PAB, both compounds reversed RV chamber and cellular hypertrophy, reduced RV interstitial and perivascular fibrosis, and improved RV function.We demonstrated that sunitinib and sorafenib reversed RV remodeling and significantly improved RV function measured via a range of invasive and non-invasive cardiopulmonary endpoints in experimental models of RV hypertrophy.

Although human gait is typically studied in a laboratory environment, the findings of laboratory-based gait assessments are often applied to daily life scenarios. Assessing gait in varied conditions may offer a better understanding of the influence of environment on gait performance.How do spatiotemporal gait measures differ between indoor overground walking, outdoor walking, and treadmill walking in healthy adults? Do different walking environments exaggerate age-related alterations in gait performance in older compared to young adults?30 young (18−30yrs) and 28 older adults (60−80yrs) completed four randomized conditions at their typical, comfortable walking pace: 1) 8 m of indoor walking, 2) continuous indoor walking, 3) treadmill walking, and 4) outdoor walking on a sidewalk. Wearable inertial sensors recorded gait data and the magnitudes and variability (in standard deviations) of the following gait measures were computed: cadence, percent double support, stride length (with sample entropy), and gait velocity.Despite the lack of significant univariate interactions between group and walking condition, significant main effects for condition and group were observed in both the magnitude and variability analyses. Treadmill walking resulted in a slower gait with shorter, less variable strides (p < .001), while walking outdoors resulted in faster gait with longer strides (p < .001) compared to other walking conditions. Stride length regularity was reduced when walking outdoors compared to treadmill walking (p = .019).The results showed that the effects of walking condition on gait measures were more dramatic than participant age, and gait performance differs between walking environments in both older and younger adults. Since daily life gait encompasses both tightly controlled and unconstrained, free-living walking, researchers and clinicians should use caution when generalizing gait performance across walking conditions. Measures of gait performance typically used in laboratory gait analyses may not adequately characterize daily life gait in indoor and outdoor environments.

Aim: To study the causes of locomotor dysfunction, estimate muscle forces, or understand the influence of altered sarcomere and muscle properties and behaviours on whole body function, it is necessary to examine the leverage with which contractile forces operate. At the ankle joint, current methods to quantify this leverage for the plantarflexors do not account for curvature of the Achilles tendon, and so may not be appropriate when studying equinus gait. Thus, novel methodologies need to be developed and implemented to quantify the Achilles tendon moment arm length during locomotion. Methods: Plantarflexor internal moment arm length and effective mechanical advantage of 11 typically developed young adults were calculated throughout stance, while heel-toe walking and voluntarily toe-walking on an instrumented treadmill. Achilles tendon moment arm was defined in two-ways: (1) assuming a straight tendon, defined between the gastrocnemius medialis myotendinous junction and Achilles tendon insertion point, and (2) accounting for tendon curvature, by tracking the initial path of the Achilles tendon from the calcaneal insertion. Results: When accounting for tendon curvature, Achilles tendon moment arm length and plantarflexor effective mechanical advantage did not differ between walking conditions (p > 0.05). In contrast, when assuming a straight tendon, Achilles tendon moment arm length (p = 0.043) and plantarflexor effective mechanical advantage (p = 0.007) were significantly greater when voluntary toe-walking than heel-toe walking in late stance. Discussion: Assuming a straight Achilles tendon led to a greater Achilles tendon moment arm length and plantarflexor effective mechanical advantage during late stance, compared to accounting for tendon curvature. Consequently, plantarflexor muscle force would appear smaller when assuming a straight tendon. This could lead to erroneous interpretations of muscular function and fascicle force-length-velocity behaviour in vivo, and potentially inappropriate and ineffective clinical interventions for equinus gait.

BACKGROUND:High-grade spondylolisthesis (HGS) (Myerding grade III-V) in adolescents can lead to a marked alteration of gait pattern and maybe the presenting symptom in these patients. This characteristic gait pattern in patients with HGS has been referred to as the "pelvic waddle." Modern 3-dimensional (3D) gait analysis serves an important tool to objectively analyze the different components of this characteristic gait preoperatively and postoperatively and is an objective measure of postoperative improvement.This study demonstrates the use of 3D gait analysis preoperatively and postoperatively in a cohort of 4 consecutive patients with HGS treated surgically at a single tertiary referral center and utilize this to objectively evaluate outcome of surgical treatment in these patients. This has not been reported previously in a cohort of patients.METHODS:This is a prospective analysis of patients with HGS who underwent surgical intervention for spondylolisthesis at a single institution. Patient demographics, clinical, and radiologic assessment were recorded, and all patients underwent 3D gait analysis before and after surgical intervention. Kinetic, kinematic, and spatial parameters were recorded preoperatively and postoperatively for all patients. This allowed the outcome of change in gait deviation index, before and after surgical treatment, to be evaluated.RESULTS:We were able to review complete records of 4 adolescent patients who underwent surgical treatment for HGS. Mean age at surgery was 13.5 years with a minimum follow-up of 2.5 years postoperatively (average 40 mo). Preoperative gait analysis revealed marked posterior pelvic tilt in 2 patients, reduced hip and knee extension in all 4 patients and external foot progression in 3 of the 4 patients. Along with an observed improvement in gait, there was an objective improvement in gait parameters postoperatively in all 4 patients. Gait deviation index score improved significantly from 78.9 to 101.3 (mean).CONCLUSIONS:Preoperative gait abnormalities exist in HGS and can be objectively analyzed with gait analysis. Surgical intervention may successfully resolve these gait abnormalities and gait analysis is a useful tool to assess the outcome of surgery and quantify an otherwise intangible benefit of surgical intervention.LEVEL OF EVIDENCE:Level IV-case series.

The complex three-dimensional structure of the tendon allows for transmission of force generated by muscles to bone. This transmission is what makes joint movement possible. During movement, tendons are exposed to different forces in a variety of directions. These forces can lead to tendon injury. Currently, tendon injuries are treated utilizing either the conservative or surgical approach or some combination of the two. Experimentation in several niches of tissue regeneration has yielded promising results regarding their eventual clinical implementation. These treatment modalities include growth factor delivery, stem cell therapy, grafts utilizing biomimetic scaffolds, gene therapy, application of mechanical forces, and administration of sound and electromagnetic waves to the affected tissue. Therapies aim to either improve the mechanical durability of the tendon or augment its healing potential.

In children with developmental dysplasia of the hip (DDH), Salter’s innominate osteotomy aims to surgically manipulate the acetabulum to increase anterior coverage and aid joint support. Consequently, this procedure may retrovert the acetabulum, predisposing patients to pain, osteoarthritis, impingement, or further surgical intervention. In this study, we aim to address whether the innominate osteotomy leads to acetabular retroversion postoperatively or at follow-up. Ninety-two patients were identified from our institutions DDH database between 2009 and 2016, who underwent a unilateral innominate osteotomy for DDH, performed by expert surgeons in a leading paediatric hospital. A novel technique was utilized to measure acetabular version on postoperative computed tomography (CT) scans, where acetabular version was compared between the pathological and contralateral control hips. Measurement of acetabular version in postoperative and control hips demonstrated no incidence of acetabular retroversion. A significant difference was observed when comparing the acetabular version of control versus post-operative hips ( P < 0.001), where hips postinnominate osteotomy had a larger degree of acetabular anteversion compared to the control hip. Furthermore, on follow-up radiographic imaging, there was no evidence of acetabular retroversion when using previously defined markers. This study confirms that the Salter innominate osteotomy does not lead to acetabular retroversion both immediately post-operatively and throughout follow-up. In fact, it demonstrates that the acetabula are more anteverted than the contralateral control hip, which has not been previously documented. Additionally, this study demonstrates a novel method of measuring acetabular retroversion using CT technology that adjusts for pelvic tilt, which is repeatable among individuals.