View source for Genu varum

{{short description|Varus deformity marked by (outward) bowing at the knee}}
{{Redirect|Bow legs||Bowlegs (disambiguation)}}
{{Redirect|Bow-leg|the robotic leg|Bow Leg}}

{{Infobox medical condition (new)
| name            = Genu varum
| image           = XrayRicketsLegssmall.jpg
| caption         = X-Ray of the legs in a 2 year old child with rickets
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| field           = [[orthopædics]]
| synonyms        =   Bow-leggedness
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'''Genu varum ''' (also called '''bow-leggedness''', '''bandiness''', '''bandy-leg''', and '''tibia vara''') is a [[varus deformity]] marked by (outward) bowing at the [[knee]], which means that the lower [[Human leg|leg]] is angled inward ([[anatomical terms of location#Medial and lateral|medially]]) in relation to the [[thigh]]'s axis, giving the limb overall the appearance of an archer's [[bow (archery)|bow]].  Usually medial angulation of both lower limb bones ([[fibula]] and [[tibia]]) is involved.<ref>{{cite journal |vauthors= Brooks WC, Gross RH |date= November 1995|title=Genu Varum in Children: Diagnosis and Treatment|url=https://dx.doi.org/10.5435/00124635-199511000-00003 |journal=Journal of the American Academy of Orthopaedic Surgeons |volume=3 |issue=6 |pages=326–335 |doi= 10.5435/00124635-199511000-00003|pmid= 10790671|s2cid= 36449933|access-date= 23 July 2021|url-access=subscription}}</ref>

==Causes==
If a child is sickly, either with [[rickets]] or any other ailment that prevents ossification of the bones or is improperly fed, the bowed condition may persist. Thus the chief cause of this deformity is [[rickets]]. Skeletal problems, [[infection]], and [[tumor]]s can also affect the growth of the leg, sometimes giving rise to a one-sided bow-leggedness.  The remaining causes are occupational, especially among [[jockey]]s, and from [[physical trauma]], the condition being very likely to supervene after accidents involving the [[Condyle (anatomy)|condyles]] of the [[femur]].<ref name=EB1911/>

===Childhood===
Children until the age of 3 to 4 have a degree of genu varum. The child sits with the soles of the feet facing one another; the [[tibia]] and [[femur]] are curved outwards; and, if the limbs are extended, although the ankles are in contact, there is a distinct space between the knee-joints. During the first year of life, a gradual change takes place. The knee-joints approach one another; the [[femur]] slopes downward and inward towards the knee joints; the [[tibia]] become straight, and the sole of the [[foot]] faces almost directly downwards.{{citation needed|date=October 2020}}

While these changes are occurring, the bones, which at first consist principally of [[cartilage]], are gradually becoming [[ossified]]. By the time a normal child begins to walk, the lower limbs are prepared, both by their general direction and by the rigidity of the bones which form them, to support the weight of the body.<ref name=EB1911>{{EB1911|inline=1 |wstitle=Bow-Leg |volume=4 |pages=343–344}}</ref>

===Rickets===
Nutritional [[rickets]] is an important cause of childhood genu varum or bow legs in some parts of the world. Nutritional rickets is due to unhealthy life style habits as insufficient exposure to sun light which is the main source of vitamin D. Insufficient dietary intake of calcium is another contributing factor. Rickets may also have genetic causes, occasionally called resistant rickets.<ref name= Paediatr>{{cite journal|last1= Creo|first1= AL|last2=Thacher|first2= TD|last3=Pettifor|first3=JM|last4=Strand|first4=MA|last5= Fischer|first5= PR| title= Nutritional rickets around the world: an update. Paediatr Int Child Health.|journal= Paediatr Int Child Health.|date=6 December 2016|volume=37|issue=2|pages= 84–98|doi=10.1080/20469047.2016.1248170|pmid= 27922335|s2cid= 6146424}}</ref> Rickets usually causes bone deformities in all four extremities. Genu varum may resolve spontaneously with modification of life style activities or after receiving medical treatment. Some deformities do not correct spontaneously and need surgical intervention especially if they are severe and causing gait difficulties. The main surgical modality used to treat genu varum arising from rickets is guided growth surgery, also known as growth modulation surgery.<ref name=JAAOSGlobal>{{cite journal|last1= EL-Sobky|first1=TA|last2=Samir |first2=S|last3=Baraka |first3=MM|last4=Fayyad |first4=TA |last5=Mahran |first5=MA |last6=Aly |first6=AS |last7= Amen |first7=J |last8= Mahmoud |first8=S| title= Growth modulation for knee coronal plane deformities in children with nutritional rickets: A prospective series with treatment algorithm.|journal= JAAOS: Global Research and Reviews|date=1 January 2020|volume=4|issue=1|pages=e19.00009|doi=10.5435/JAAOSGlobal-D-19-00009|pmid=32159063|pmc=7028784|doi-access=free}}</ref>

===Blount's disease===
[[Blount's disease]] is a deformity in the legs, mostly from the knees to the ankles. The affected bone curves in or out and forms the usual "archers bow" which can also be called bow-legs. There are two types of Blount's disease. The first type is Infantile: this means that children under four are diagnosed with this disease. Blount's disease in this age is very risky because sometimes it is not detected and it passes to the second type of Blount's disease. The second type of Blount's disease is found mostly in older children and in teenagers, sometimes in one leg and sometimes in both; the patient's age determines how severe the diagnosis is.<ref>{{cite web |last=Shriner's |first=Hospital for Children – Houston, TX |title=Blount's Disease |url=http://www.shrinershospitalsforchildren.org/en/Hospitals/Locations/Houston/Orthopaedics/Blounts.aspx |access-date=October 28, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20111126055643/http://www.shrinershospitalsforchildren.org/en/Hospitals/Locations/Houston/Orthopaedics/Blounts.aspx |archive-date=November 26, 2011 }}</ref>

===Osteochondrodysplasia===
[[Osteochondrodysplasia]] are a diverse group of genetic bone diseases or genetic skeletal dysplasias that manifest in generalized bone deformities involving the extremities and the spine. Bow legs or genu varum is one of these deformities. The characteristic bone X-ray survey findings are important to confirm the diagnosis.<ref name=elsobky2017>{{cite journal|last1=EL-Sobky|first1=TA|last2=Shawky|first2=RM|last3=Sakr|first3=HM|last4=Elsayed|first4=SM|last5=Elsayed|first5=NS|last6=Ragheb|first6=SG|last7=Gamal|first7=R|title=A systematized approach to radiographic assessment of commonly seen genetic bone diseases in children: A pictorial review.|journal= J Musculoskelet Surg Res|volume=1|issue=2|pages=25|date=15 November 2017|doi=10.4103/jmsr.jmsr_28_17|s2cid=79825711 |doi-access=free }}</ref>

==Diagnosis==
[[File:Hip-knee-ankle angle.png|thumb|75px|Hip-knee-ankle angle.]]
On [[projectional radiography]], the degree of varus or valgus deformity can be quantified by the ''hip-knee-ankle angle'',<ref name=dahl2009>{{cite journal|last1=W-Dahl|first1=Annette|last2=Toksvig-Larsen|first2=Sören|last3=Roos|first3=Ewa M|title=Association between knee alignment and knee pain in patients surgically treated for medial knee osteoarthritis by high tibial osteotomy. A one year follow-up study|journal=BMC Musculoskeletal Disorders|volume=10|issue=1|pages=154|year=2009|issn=1471-2474|doi=10.1186/1471-2474-10-154|pmid=19995425|pmc=2796991 |doi-access=free }}</ref> which is an angle between the femoral mechanical axis and the center of the [[ankle joint]].<ref name="CherianKapadia2014">{{cite journal|last1=Cherian|first1=Jeffrey J.|last2=Kapadia|first2=Bhaveen H.|last3=Banerjee|first3=Samik|last4=Jauregui|first4=Julio J.|last5=Issa|first5=Kimona|last6=Mont|first6=Michael A.|title=Mechanical, Anatomical, and Kinematic Axis in TKA: Concepts and Practical Applications|journal=Current Reviews in Musculoskeletal Medicine|volume=7|issue=2|year=2014|pages=89–95|issn=1935-973X|doi=10.1007/s12178-014-9218-y|pmid=24671469|pmc=4092202}}</ref> It is normally between 1.0° and 1.5° of varus in adults.<ref name="SheehyFelson2011">{{cite journal|last1=Sheehy|first1=L.|last2=Felson|first2=D.|last3=Zhang|first3=Y.|last4=Niu|first4=J.|last5=Lam|first5=Y.-M.|last6=Segal|first6=N.|last7=Lynch|first7=J.|last8=Cooke|first8=T.D.V.|title=Does measurement of the anatomic axis consistently predict hip-knee-ankle angle (HKA) for knee alignment studies in osteoarthritis? Analysis of long limb radiographs from the multicenter osteoarthritis (MOST) study|journal=Osteoarthritis and Cartilage|volume=19|issue=1|year=2011|pages=58–64|issn=1063-4584|doi=10.1016/j.joca.2010.09.011|pmid=20950695|pmc=3038654}}</ref> Normal ranges are different in children.<ref name=Sabharwal2009>{{cite journal|last1=Sabharwal|first1=Sanjeev|last2=Zhao|first2=Caixia|title=The Hip-Knee-Ankle Angle in Children: Reference Values Based on a Full-Length Standing Radiograph|journal=The Journal of Bone and Joint Surgery, American Volume|volume=91|issue=10|year=2009|pages=2461–2468|issn=0021-9355|doi=10.2106/JBJS.I.00015|pmid=19797583}}</ref>
<gallery widths=240 heights=170>
File:Hip-knee-ankle angle by age.png|''Hip-knee-ankle angle'' by age, with 95% [[prediction interval]].<ref name=Sabharwal2009/>
</gallery>

==Treatment==
[[File:Osteotomy tibia en.svg|thumb|Valgus osteotomy. The black line is the mechanical axis. This process may be done to correct a [[varus deformity]].]]
Generally, no treatment is required for [[Idiopathic disease|idiopathic]] presentation as it is a normal anatomical variant in young children. Treatment is indicated when it persists beyond {{frac|3|1|2}} years old. In the case of unilateral presentation or progressive worsening of the curvature, when caused by [[rickets]], the most important thing is to treat the constitutional [[disease]], at the same time instructing the care-giver never to place the child on their feet. In many cases, this is quite sufficient in itself to effect a cure, but matters can be hastened somewhat by applying [[splint (medicine)|splints]]. When the deformity arises in older patients, either from [[physical trauma|trauma]] or occupation, the only permanent treatment is [[surgery]], but [[orthopaedic]] bracing can provide relief.{{citation needed|date=October 2020}}

===Rickets===
[[Rickets]] usually causes bone deformities in all four extremities. Genu varum may resolve spontaneously with modification of lifestyle activities or after receiving medical treatment. Some deformities do not correct spontaneously and need surgical intervention especially if they are severe and causing gait difficulties. The main surgical modality used to treat genu varum arising from [[rickets]] is guided growth surgery, also known as growth modulation surgery.<ref name=JAAOSGlobal />

===Blount's disease===
Treatment for children with Blount's disease is typically braces but surgery may also be necessary. In children guided growth surgery is used to gradually correct/straighten the bow legs.<ref name=Orthop2019>{{cite journal|last1= Journeau|first1=P| title= Update on guided growth concepts around the knee in children.|journal= Orthop Traumatol Surg Res|volume=S1877-0568|issue=19|pages=S171–S180|doi=10.1016/j.otsr.2019.04.025|pmid=31669550|year=2020|doi-access=free}}</ref>  For teenagers osteotomy or bone cutting is often used to correct the bone deformity. The operation consists of removing a piece of tibia, breaking the fibula and straightening out the bone; there is also a choice of elongating the legs. If not treated early enough, the condition worsens quickly.<ref>{{cite web|last=PubMed|first=Health|title=Blount's Disease|url=https://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002551/|access-date=October 28, 2011}}</ref>

===Osteochondrodysplasia===                       
Guided growth surgery in children is widely used to achieve gradual correction of knee deformities arising from [[Osteochondrodysplasia]] including genu varum. Yet, this treatment is associated with a high incidence of recurrence and repeated surgeries may be needed to maintain proper bone alignment.<ref name=Orthop2019 /><ref name=elsobky2017 />

==Prognosis==

In most cases persisting after childhood, there is little or no effect on the ability to walk.  Due to uneven stress and wear on the knees, however, even milder manifestations can see an accelerated onset of [[arthritis]].<ref>{{cite web |url=https://www.lecturio.com/concepts/genu-varum/| title=Genu Varum|website=The Lecturio Medical Concept Library |access-date= 23 July 2021}}</ref>

==See also==
* [[Genu valgum]]
* [[Genu recurvatum]]
* [[Varus deformity]]
* [[Rickets]]
* [[Knee pain]]
* [[Knee osteoarthritis]]

==References==
{{reflist}}

== External links ==
* {{cite web|title=Bowed Legs|url=http://orthoinfo.aaos.org/topic.cfm?topic=a00230|publisher=American Academy of Orthopaedic Surgeons|quote=Reviewed by members of POSNA (Pediatric Orthopaedic Society of North America)}}
{{Medical resources
|   DiseasesDB     = 29404
|   ICD10          = {{ICD10|Q|68|3|q|65}}-{{ICD10|Q|68|5|q|65}}, {{ICD10|Q|74|1|q|65}} 
|   ICD9           = {{ICD9|755.64}} congenital;  {{ICD9|736.42}} acquired
|   ICDO           =
|   OMIM           =
|   MedlinePlus    = 001585
|   eMedicineSubj  =
|   eMedicineTopic =
|   MeshID         =
}}
{{Congenital malformations and deformations of musculoskeletal system}}

[[Category:Congenital disorders of musculoskeletal system]]
[[Category:Knee injuries and disorders]]