[,n,q.nxrNcro Ger AnouNn In both snowplowingand reverse snowplowing the large,heavy head servesas a balancing tool while the legs and feet push the child The physicalcharacteristics just listed not only help explain why motor I forward: I developmenrmay be delayedbut, in addition, help explain unusual I movement strategies that are often seen in children with achondroplasia. Many children with achondroplasiado not pass through the customary stagesof ambulatory developmentthat lead to iearninghow to walk. Often, a child's chosenmethods of gettingaround causeworry for parents,and often for the child's doctors,too. Both physicii ns and parents tend to expect a particular sequenceof development in all babies. This includes, for example, traditional, reciprocal crawling. [Crawling on handsand kneesseems so universal that, in fact, a discredited and untrue theory postulatedthat children who failed to learn to crawl would have, as a consequence,serious developmentaland behavioral problems later in life.l

But many children with achondroplasiachoose alternative methods snowplowing of getting around.Many never crawl in the traditional fashion.Indeed, only about 20Voof children with achondroplasiaever crawl in that traditional way. Crawling often is not a very efficient way to get around tbr a child with achondroplasia.Short arms and short legs meansthat children with achondroplasiawho try to crawl in the traditional way rnay find that their plump bellies are still dragging on the floor. And, traditionai crawling requires a child to be able to hold the head up. Becausechildren with achondroplasiahave lzrge andheavy heads, as weli as hypotonia and instability of the neck, holding the head up in a crawling position for an extendedperiod is difficult.

Instead,many infants and young children with achondroplasiachoose alternative strategies that circumvent the problems that arise with reversesnowplowing traditional crawling. Many may choose 'snowplowing', 'reverse More than half of children with achondropiasiachoose to snowplow snowplowing'or'spider crawling'. at somepoint and nearly half usereverse snowplowing as a way of moving from place to place. Spidercrawling is almost never PosrrroNTuNsrtrons seen in children of average stature but is used by about a The combinationof short limbs, excessivelymobile hips and'trunk, quarter of children with unstable knees and a large head often results in children with achondroplasia.Spider crawling, achondroplasiademonstrating unusual, but adaptive,ways of getting in contrast to traditional from sitting to standing.Children of averagestature most often will crawling, which is on the hands transition by first going to a squatting or kneeling position and then and knees,involves support by standing up. In contrast,many children with achondroplasialearn to the handsand feet. Although the 'jackknife'. head needs to be supported, spider crawling more easily Jackknifing begins with the child allows the belly to be cleared fully extending the legs while tiom the floor. spider crawling sitting. Next, bending only at the waist, the body is fully flexed and In addition to theseunusual methods of getting around,many children the head is placed on the floor. with achondroplasia will show long preference for army crawling, Using the head for balance, the logrolling or seatscooting. Logrolling may be particularly common in child next wedges up over fully children with achondroplasia(and is the preferredmeans of locomotion extendedlegs - pushingwith the ilJ"T!"*'Tl legs, followed by extensionof the ffi\a 4Sq^gf the.needrorjoint torso. Remarkably, this results in tf'l4lt- Jd transition from sitting to standing logrolln0 M'*proilrr stabilization and 'Frpu,rrs without everbending the knees.We r-..,Fk muscle strength suspectthat this strategyis chosen ntlb/ in the arms and legs.Likewise, principally because of the flfA-- instability of the knees seen in mdlisal oilfng fu..anny ilw{ng afm} CfaWling d- .0,0...t"ro with achon- allows the weight many children r-1 allows (ra? Fqf/ ('t.J to be distributed droplasia. Jackknifing with the knees straight iL hb L6 to the hands, transition rising from a l&-i -(B- arms, stomach, and locked, while legs and feet and kneel or squat requires dynamic the knees - allows the head to be periodically restedon the floor; this is probably stabilization of for helpt'ul in a child with hypotonia, joint hypermobility and a heavy something that is very hard head. many childrenwith achondroplasia. 'Wedging up'is a Frun Moron Sru,ls somewhat lessde- sirable method of children with achondroplasiaoften useunusual tran-sitioning to methodsto hold writing implements. Becauseof the child's standing. Some short fingers, the excessive separationbetween the middle and ring children will push fingers and hypermobility of the finger joints, often crayonsor pencits oneleg our straight win be used with a two- finger or four-finger grip rather than the more and then use that traditional pencil grip. one straight leg ro support all of the body's weight in getting to stand. Unf ortun ate ly, wedging up over one leg seemsto increasethe chanceof progressive soft tissue instability at the knee and may make more likely the need for surgicai intervention.

Dressingand undressingmay pose a problem as well becauseof limb Thesegrips, while 'abnormal',are, in fact, adaptiveand should not be shortening,limited elbow extension, a prominent bottom and a heavy discouraged.Many adultswith achondroplasiause a two-finger method head. Some children without sacrificing quality or efficiency of handwriting. learn unusualways of surmounting such problems, taking ad- Scissorsalso may be problematic. vantage of trunk mo- In addition to the hand bility to compensate characteristicsdescribed, children for ttreshortreach, and with achondroplasiaoften have figuring out a way to excessiveelbow pronation(palm stabilize the head at down) and either limitation or the sametime. reluctanceto useelbow supination (palm up). Such supinationis necessaryfor traditional scissor use. WHBn CeN I Expncr Mv Cnu,D To...... To CBISBRATE

Principailybecause of variousphysical features,children with achon- PaLetits,pirl,sicilrrt, cariy chikl- droplasianot only have some unusualadaptive ways to perform hooil eclucatol'sriltii thelapists motor tasks,but, overall show delaysin attainingmany develop- shoulcli'cccignizc iilai the diller- nrentalskills. Such delaysusually do not reflectcognitive limits. cjntlltoveiliunr stratcqies exhibited The tablelists certain milestonesthat parents often observe, the av- by a cliiicl rr,'iih;rcituticli oirlasia are erageage at which average staturedchildren attain these skills and rr()t trsttllll)' ii,.':trrqi l{}l' w(}fr}/ ll()f the rangesof agewithin which most childrenwith achondroplasia should tirei' be tiiuugirt of as ab- accomplishthe sameskills. rloftttill.Tirt- cirii'-r is sirnlily adapt- irrg to liis .ri'hi-r plivsicii dift-er- cnccs. ln iucl. lire:,ririiitl, of chil- Range (in Months) AverageAge in ch'enrvith aulioiitii'uirlasiirtu invent for Children with Average Statured Achondroplasia Children (in and utiiizc ulteciiri,- aitciiiative (25th-90th Voile) Months) rrraysof doiirg il.riirgsiciiccts thcir i'cstrurccti|lnc)ss aii(l problern sr-rlv- Sit, without support* 9 - 20.5 ).) iirg skills and, tlreii,is sornething Pull to stand 12-20 7.5 to t'clebrotc. Stand alone 16-29 11.5 Walk 14-27 t2 i:ol furthtr irrtirrnrirrnl .rin Reach 6 -15 3.5 l,rf.lIi nil! 11r-!ri{r!t: (L|r (',..niiiirl\)i Pass icli LP,\ Frirf t object 8.5-14 6 iijl;:'i'ili;' ^'' Rt)bti Ll(ll) Jir.i,h.crl Bang 2 objects ii) I i) OIr rrpr.r\\'a, 9-14 8.5 llllilililiil,i""" I on!\ lc1r. W,\ 9,\6 1-1 Scribble hlllri/$\isrlrls u.s(l rJur.lrrarii'nt (itr{))b-in 027(r 15-30 13.5 j.lrohscildtorn: (onl LP,\ Dis. Lrssion (jro.,p on I rlc lc \UhscribC: scrrl cntitii l,r ,;:t-ctr:' ilc tl.Crlu' dt nrc:s!ca l)l)!. suh\.1'rt\' rl\irill\rr *We activcly tiiscouage 1i-rsond nle!5tgafr: {nLl Ir ri\ii!1i.tn0,n(rll.cdu unsuppoftd sitting prior to ar le6r 12- 14 months of age tn babies with rchotrdroDlasia.

(ithr-r R(.;ourcas:

phr sicrrnsin 1our :rra. anJ muc| lt, I c: l-80{}-24Dr*ARl' If your child's development is substantially outside of the ranges fi,in\i'r!!! lr\ Su,,i$ iiiri,iir) given you shouldtalk more with your child's physician. Ncu )ilLk: Ldrhf('ir.I ce .'r Slcir,r.l tlo.k\. 1.,E6 l.\...".

QfrAftul,_TlfqEi.ti;ly 11l Fn;r.iI rrl Crrrrlq b) f lrarlcr irrLr. Nr,nc,.Nlrirur iiiilrrr.t Cr.inJlii lnJ jr,rt \\cr.s livinc. CA: Sh\,il Strrur.' lnrrrlrricrl N llrtirnDrliunCcnrer. llrc.. I 99"1 I9; pit"e.

!.tilsjttl pli i r'.!q'!., !:rtrl! Lirtr!\, ! i! I!!d!,.!l!!. b) J,\rn,\bl!.r Nc\\ )ink: Prr.s.r r('rr.'r,'.,.,rr1, t!rRN. lr/-1pa;as