Cerebral palsy

===Skeleton===
For bones to attain their normal shape and size, they require the stresses from normal musculature.<ref name="Mughal2014" /> People with cerebral palsy are at risk of low [[bone mineral density]].<ref>{{cite journal | vauthors = Ozel S, Switzer L, Macintosh A, Fehlings D | title = Informing evidence-based clinical practice guidelines for children with cerebral palsy at risk of osteoporosis: an update | journal = Developmental Medicine and Child Neurology | volume = 58 | issue = 9 | pages = 918–923 | date = September 2016 | pmid = 27435427 | doi = 10.1111/dmcn.13196 | doi-access = free }}</ref> The shafts of the bones are often thin (gracile),<ref name="Mughal2014" /> and become thinner during growth. When compared to these thin shafts ([[diaphyses]]), the centres ([[metaphyses]]) often appear quite enlarged (ballooning).<ref>{{Cite thesis |title=Postural control in children with cerebral palsy: a comprehensive definition, framework and reproducible assessment. |url=http://dx.doi.org/10.14264/90c2cf3 |publisher=University of Queensland Library |first=Rosalee Maree |last=Dewar|year=2020 |doi=10.14264/90c2cf3 }}</ref> Due to more than normal joint compression caused by muscular imbalances, [[articular cartilage]] may atrophy,<ref name="Kerkovich, D 2009, pp. 41-53" />{{rp|46}} leading to narrowed joint spaces. Depending on the degree of spasticity, a person with CP may exhibit a variety of angular joint deformities. Because vertebral bodies need vertical gravitational loading forces to develop properly, spasticity and an abnormal gait can hinder proper or full bone and skeletal development. People with CP tend to be shorter in height than the average person because their bones are not allowed to grow to their full potential. Sometimes bones grow to different lengths, so the person may have one leg longer than the other.<ref>{{cite journal | vauthors = Riad J, Finnbogason T, Broström E | title = Leg length discrepancy in spastic hemiplegic cerebral palsy: a magnetic resonance imaging study | journal = Journal of Pediatric Orthopedics | volume = 30 | issue = 8 | pages = 846–850 | date = December 2010 | pmid = 21102211 | doi = 10.1097/BPO.0b013e3181fc35dd | hdl-access = free | s2cid = 46608602 | hdl = 10616/40477 }}</ref><ref>{{Cite journal |last1=Kim |first1=Hyo Sung |last2=Son |first2=Su Min |date=2022-08-10 |title=Limb Length Discrepancy and Corticospinal Tract Disruption in Hemiplegic Cerebral Palsy |journal=Children |volume=9 |issue=8 |pages=1198 |doi=10.3390/children9081198 |doi-access=free |issn=2227-9067 |pmc=9406518 |pmid=36010088}}</ref>

Children with CP are prone to [[low trauma fractures]], particularly children with higher [[Gross Motor Function Classification System]] (GMFCS) levels who cannot walk. This further affects a child's mobility, strength, and experience of pain, and can lead to missed schooling or child abuse suspicions.<ref name="Mughal2014" /> These children generally have fractures in the legs, whereas non-affected children mostly fracture their arms in the context of sporting activities.<ref>{{cite journal | vauthors = Veilleux LN, Rauch F | title = Muscle-Bone Interactions in Pediatric Bone Diseases | journal = Current Osteoporosis Reports | volume = 15 | issue = 5 | pages = 425–432 | date = October 2017 | pmid = 28856575 | doi = 10.1007/s11914-017-0396-6 | s2cid = 39445049 }}</ref>

[[Hip dislocation]] and [[toe walking|ankle equinus]] or [[pes cavus|plantar flexion deformity]] are the two most common deformities among children with cerebral palsy. Additionally, flexion deformity of the hip and knee can occur. Torsional deformities of long bones such as the [[femur]] and [[tibia]] are also encountered, among others.<ref name="elsobky2017" /><ref name="shore2010" /> Children may develop [[scoliosis]] before the age of 10 – estimated [[prevalence]] of scoliosis in children with CP is between 21% and 64%.<ref name="Cloake2016" /> Higher levels of impairment on the GMFCS are associated with scoliosis and hip dislocation.<ref name="elsobky2017" /><ref>{{cite journal | vauthors = Rutz E, Brunner R | title = Management of spinal deformity in cerebral palsy: conservative treatment | journal = Journal of Children's Orthopaedics | volume = 7 | issue = 5 | pages = 415–418 | date = November 2013 | pmid = 24432104 | pmc = 3838520 | doi = 10.1007/s11832-013-0516-5 }}</ref> Scoliosis can be corrected with surgery, but CP makes surgical complications more likely, even with improved techniques.<ref name="Cloake2016" /> Hip migration can be managed by soft tissue procedures such as adductor musculature release. Advanced degrees of hip migration or dislocation can be managed by more extensive procedures such as femoral and pelvic corrective [[osteotomy|osteotomies]]. Both soft tissue and bony procedures aim at prevention of hip dislocation in the early phases or aim at hip containment and restoration of anatomy in the late phases of disease.<ref name="elsobky2017" /> Equinus deformity is managed by conservative methods especially when dynamic. If fixed/static deformity ensues surgery may become mandatory.<ref name="shore2010" />

[[Adolescence#Growth spurt|Growth spurts]] during [[puberty]] can make walking more difficult for people with CP.<ref>{{cite journal| vauthors = Roberts A |title=The surgical treatment of cerebral palsy|journal=[[Paediatrics and Child Health]]|date=September 2012|volume=22|issue=9|pages=377–383|doi=10.1016/j.paed.2012.03.004}}</ref>