Desarrollos turísticos actuales MAPA: Desarrollos turísticos actuales

Cerebral palsy (CP) describes a group of permanent motor disorders that result from an injury to the developing brain either before or shortly after birth (Rosenbaum et al., 2007). Children with CP demonstrate a range of motor impairments, including hypertonicity, weakness, and poor motor control. The most common musculoskeletal impairment affecting this group is equinus deformity (Cornell, 1985) which is associated with triceps surae spasticity and shortened length (i.e., static or dynamic contracture), as well as functional gait quality impairments such as excessive plantarflexion in stance phase, poor swing leg clearance, and impaired balance and stability (Davids, 2009; Perry & Burnfield, 2010; Svehlik, Zwick, Steinwender, Kraus, & Linhart, 2010; Wren, Do, & Kay, 2004; Wren, Rethlefsen, & Kay, 2005). Altered talocrural motion and hindfoot malalignment associated with equinus may influence the development of excessive midfoot motion, resulting in lever arm dysfunction and pain (Karas, 2002; Maurer et al., 2013). This muscle shortening may alter the plantarflexors’ length-tension curves and reduce their ability to produce force (Davids, 2009; Foran, Steinman, Barash, Chambers, & Lieber, 2005; Lieber, 2002). Foot deformity and altered biomechanics may lead to chronic overuse and pain, and affect long-term ambulation outcomes in individuals with CP (Bleck, 1987; Bottos & Gericke, 2003; Davids, 2009; Jahnsen et al., 2004; Murphy et al., 1995; Opheim et al., 2009).

Ankle-foot orthoses (AFOs) are one of the most common non-operative interventions prescribed to address these concerns (Novacheck, 2008; Wingstrand et al., 2014). Mechanically, AFOs can help restore normal joint motion and walking patterns for children with equinus by compensating for weakness and hypertonicity (especially ankle plantarflexor and dorsiflexor muscle weakness and gastrocnemius hypertonicity), and redirecting the ground reaction force vector to optimize knee and hip kinematics and kinetics (Butler et al., 2007; Butler & Nene, 1991; Meadows et al., 2008; Novachek et al., 2009; Uustal, 2008).

In order for AFOs to achieve the optimum effect for each child, the child’s individual characteristics (gait pattern, clinical examination) should be matched to the mechanical

properties and design of the orthosis (Davids et al., 2007; Singerman, Hoy, & Mansour, 1999). Ideally, the design is determined collaboratively by the team and outlined in the prescription (Kane et al., 2018; Uustal, 2008). An important and often overlooked aspect of individualized AFO prescription is the angle of the ankle joint within the AFO (AA-AFO) (Jagadamma et al., 2015; Ridgewell, Dobson, Bach, & Baker, 2010). The AA-AFO is conventionally set at 90˚, in

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an attempt to maintain ankle flexibility or prevent ankle plantarflexion contracture, while allowing gait with a plantigrade foot (i.e., foot flat on the ground). However, this convention is not substantiated by evidence, and is likely based on an erroneous assumption that a 90˚ ankle with vertical shank will help the knee to extend in stance phase (Eddison & Chockalingam, 2013; Owen, 2010). This may present a problem for children with equinus, as the orthosis requires ankle dorsiflexion to 90˚ during gait (or further if a hinged or flexible design is prescribed), regardless of the severity of gastrocnemius hypertonicity or contracture.

If the AA-AFO does not fully accommodate the length and tone of the gastrocnemius muscle – which spans the knee, talocrural, and subtalar joints – several compensations are possible. Knee extension may be limited at initial contact (IC) (thus preventing IC with the heel) or during stance (Karas, 2002; Meadows et al., 2008; Nuzzo, 1983; Owen, 2010). As well, subtalar pronation may compensate for restricted talocrural dorsiflexion. When the subtalar joint pronates, the alignment of the axes of the talonavicular and calcaneocuboid joints become more parallel to allow more dorsiflexion at the forefoot and midfoot (transverse tarsal or mid-tarsal joint) compared to when the subtalar joint is in neutral or supination (Elftman, 1960; Johanson et al., 2014; Sammarco & Hockenbury, 2001). If the ankle lacks dorsiflexion ROM, the stretching force applied during dorsiflexion motion is more likely to stretch the small, extensible ligaments of the midfoot than the Achilles tendon (Karas, 2002). This makes it difficult to selectively target stretching forces to the talocrural joint and suggests that casting the ankle in a position of

excessive dorsiflexion (judged relative to the anatomy of the individual’s foot and ankle) may promote hyperpronation and/or midfoot break, potentially contributing to lever arm dysfunction and long-term pain. Recently, this rationale has led some authors to raise concerns about the practice of positioning the ankle in angles of dorsiflexion that exceed the measured

gastrocnemius length (Eddison & Chockalingam, 2013; Meadows et al., 2008; Owen, 2010; Ridgewell et al., 2010). A few authors report using plantarflexed AA-AFOs (Harrington et al., 1984; Nuzzo, 1983, 1986; Owen, 2004b), although they do not clearly describe the rationale for determining the AA-AFO. Most studies do not report the AA-AAO, or use a 90˚ ankle angle for all children regardless of clinical findings, suggesting that the rationale for determining the AA- AFO varies and does not consistently consider the length of gastrocnemius (Eddison &

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Thus, for children with CP, orthotic intervention may be more effective when the AA- AFO is individualized based on the length and stiffness of the child’s plantarflexor muscles (Eddison & Chockalingam, 2013; Jagadamma et al., 2015; Owen, 2010); however evidence- based consensus or guidelines regarding the AA-AFO do not exist.(Jagadamma et al., 2015; Kane et al., 2018) A clinical algorithm has been proposed to determine the AA-AFO (Owen, 2005); however to date it has not been evaluated in a controlled experiment. Therefore, this study aimed to explore the effects of individualizing the AA-AFO for children with CP using this algorithm; we compared the effects of the individualized AA-AFO to current conventional AFO prescription practices by examining lower extremity gait kinematics and kinetics, and functional mobility. We hypothesized that better control of the ankle joint using a solid AFO, in a position that accommodated the child’s gastrocnemius length and stiffness, would promote better

kinematics and kinetics at the knee joint and to a lesser extent at the hip. We also expected these improvements would be reflected by more typical foot and shank segment kinematics. We did not expect that functional mobility or spatio-temporal parameters would be adversely affected.

5.3 Method