{{Short description|Abnormal inward turning of the knees when straightening the legs}} {{More citations needed|date=February 2010}} {{Infobox medical condition (new) | name = Genu valgum | synonyms = Knock knee | image = Valgus.jpg | caption = A very severe case of ''genu valgum'' of the left knee following bone cancer treatment | pronounce = | field = | symptoms = | complications = | onset = | duration = | types = | causes = | risks = | diagnosis = | differential = | prevention = | treatment = | medication = | prognosis = | frequency = | deaths = }}
'''Genu valgum''', commonly called "'''knock-knee'''", is a condition in which the knees angle in and touch each other when the legs are straightened.<ref>{{cite web |url=https://www.lecturio.com/concepts/genu-valgum/| title=Genu Valgum |website=The Lecturio Medical Concept Library |access-date= 23 July 2021}}</ref> Individuals with severe valgus deformities are typically unable to touch their feet together while simultaneously straightening the legs. The term originates {{ety|la|genu|knee||valgus|bent outwards}}, but is also used to describe the distal portion of the knee joint which bends outwards and thus the proximal portion seems to be bent inwards.
Mild genu valgum is diagnosed when a person standing upright with the feet touching also shows the knees touching. It can be seen in children from ages 2 to 5, and is often corrected naturally as children grow. The condition may continue or worsen with age, particularly when it is the result of a disease, such as rickets.<ref name=elsobky2020>{{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|article-number=e19.00009|doi=10.5435/JAAOSGlobal-D-19-00009|pmid=32159063|pmc=7028784|doi-access=free}}</ref> Idiopathic genu valgum is a form that is either congenital or has no known cause.
Other systemic conditions may be associated, such as Schnyder crystalline corneal dystrophy, an autosomal dominant condition frequently reported with hyperlipidemia.
==Causes== Genu valgum can arise from a variety of causes including nutritional, genetic, traumatic, idiopathic or physiologic and infectious.<ref>{{Cite web| author = NHS | title = Knock Knees |date=January 2016 | url = http://www.childrenshospital.org/conditions-and-treatments/conditions/knock-knees/symptoms-and-causes}}</ref>
===Rickets=== Nutritional rickets is an important cause of childhood genu valgum or knock knees in some parts of the world. Nutritional rickets arises from 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.<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><ref name=elsobky2020/> Genu valgum may arise from rickets caused by genetic abnormalities, called vitamin D-resistant rickets or X-linked hypophosphatemia.
===Osteochondrodysplasia=== Osteochondrodysplasia are a variable group of genetic bone diseases or genetic skeletal dysplasias that present with generalized bone deformities involving all extremities and the spine. Genu valgum or knock knees is one of the known skeletal manifestations of Osteochondrodysplasias. A complete bone X-ray survey is mandatory to reach a definitive 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|page=25|date=15 November 2017|doi=10.4103/jmsr.jmsr_28_17|s2cid=79825711 |doi-access=free }}</ref>
==Diagnosis == right|thumb|150px|Image showing how Q-angle is measured The degree of genu valgum can clinically be estimated by the {{visible anchor|Q angle}}, which is the angle formed by a line drawn from the anterior superior iliac spine through the center of the patella and a line drawn from the center of the patella to the center of the tibial tubercle. In women, the Q angle should be less than 22 degrees with the knee in extension and less than 9 degrees with the knee in 90 degrees of flexion. In men, the Q angle should be less than 18 degrees with the knee in extension and less than 8 degrees with the knee in 90 degrees of flexion. A typical Q angle is 12 degrees for men and 17 degrees for women.<ref>{{Cite journal |author1=Mohammad-Jafar Emami |author2=Mohammad-Hossein Ghahramani |author3=Farzad Abdinejad |author4=Hamid Namazi | title = Q-angle: an invaluable parameter for evaluation of anterior knee pain | journal = Archives of Iranian Medicine | volume = 10 | issue = 1 | pages = 24–26 |date=January 2007 | pmid = 17198449}}</ref>
===Radiography=== 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|page=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="200"> File:Hip-knee-ankle angle.png|Hip-knee-ankle angle File:Hip-knee-ankle angle by age.png|''Hip-knee-ankle angle'' by age, with 95% prediction interval<ref name=Sabharwal2009/> </gallery>
==Treatment== The treatment of genu valgum in children depends on the underlying cause. Developmental also known as idiopathic genu valgum is usually self-limiting and resolves during childhood. Genu valgum secondary to nutritional rickets is typically treated with lifestyle modifications in the form of adequate sun exposure to ensure receiving the daily requirements of vitamin D and nutrition with a rich calcium diet. Additionally, calcium and vitamin D supplementations may be used. Some residual genu valgum deformities of healed nutritional rickets tend to improve spontaneously over time provided they maintain the healed status with no relapse of rachitic activity. Younger and middle-aged children under the age of eight years are more likely to remodel or self-correct spontaneously without the need for corrective surgery. Similarly, children with moderate deformities are more likely to remodel or self-correct spontaneously.<ref name=prakash2017>{{cite journal |last1=Prakash |first1=J |last2=Mehtani |first2=A |last3=Sud |first3=A |last4=Reddy |first4=BK |title=Is surgery always indicated in rachitic coronal knee deformities? Our experience in 198 knees. |journal=Journal of orthopaedic surgery (Hong Kong) |date=January 2017 |volume=25 |issue=1 |article-number=2309499017693532 |doi=10.1177/2309499017693532 |pmid=28222650|doi-access=free }}</ref><ref name=barak2025>{{cite journal |last1=Baraka |first1=Mostafa M. |last2=Samir |first2=Shady |last3=Mahmoud |first3=Shady |last4=El-Sobky |first4=Tamer A. |title=Most Coronal Knee Deformities of Healed Nutritional Rickets Under 8 Years of Age Remodel Spontaneously: Building Evidence for Practice Change |journal=Journal of Pediatric Orthopaedics |date=3 July 2025 |doi=10.1097/BPO.0000000000003028 |pmid=40605775}}</ref> This applies to angular knee deformities in general namely genu valgum and genu varum.<ref name=prakash2017/><ref name=barak2025/> Children with more severe deformities and those over the age of eight years (older children) are less likely to remodel spontaneously. Corrective surgery in the form of guided growth may be considered in such patients.<ref name=prakash2017/><ref name=barak2025/> Guided growth is the most common ''surgical'' intervention used to straighten the deformed bone.<ref name=elsobky2020/><ref>{{cite journal |last1=Dai |first1=Zhen-Zhen |last2=Liang |first2=Zhen-Peng |last3=Li |first3=Hao |last4=Ding |first4=Jing |last5=Wu |first5=Zhen-Kai |last6=Zhang |first6=Zi-Ming |last7=Li |first7=Hai |title=Temporary hemiepiphysiodesis using an eight-plate implant for coronal angular deformity around the knee in children aged less than 10 years: efficacy, complications, occurrence of rebound and risk factors |journal=BMC Musculoskeletal Disorders |date=9 January 2021 |volume=22 |issue=1 |page=53 |pmid=33422021 | doi=10.1186/s12891-020-03915-w|pmc=7797153|doi-access=free }}</ref> Genu valgum arising from osteochondrodysplasia<ref name=elsobky2017 /> usually needs repeated guided growth surgical interventions.<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|date=25 October 2019|volume=S1877-0568|issue=19|pages=S171–S180|doi=10.1016/j.otsr.2019.04.025|pmid=31669550|doi-access=free}}</ref> Genu valgum secondary to trauma depends on the degree of physical damage. Usually, limb reconstruction procedures are needed, especially if trauma occurs in the early years of life where the anticipated remaining longitudinal bone growth is great. The treatment of genu valgum in adults depends on the underlying cause and the degree of joint involvement namely arthritis. Bone corrective osteotomies and prosthetic joint replacement may be used depending upon the patient's age and symptomatology in terms of pain and functional impairment. Weight loss and substitution of high-impact for low-impact exercise can help slow progression of the condition. With every step, the patient's weight places a distortion on the knee toward a knocked knee position, and the effect is increased with increased angle or increased weight. Even in the normal knee position, the femurs function at an angle because they connect to the hip girdle at points much further apart than they connect at the knees.
Working with a physical medicine specialist such as a physiatrist, or a physiotherapist may assist a patient in learning how to improve outcomes and use the leg muscles properly to support the bone structures. Alternative or complementary treatments may include certain procedures from Iyengar Yoga or the Feldenkrais Method.
==See also== * Genu varum (bow-legs) * Genu recurvatum (back knee) * Knee pain * Knee osteoarthritis
==References== {{Reflist}}
== External links == {{Medical resources | DiseasesDB = 29408 | ICD10 = {{ICD10|Q|74|1|q|65}} | ICD9 = {{ICD9|736.41}}, {{ICD9|755.64}} | ICDO = | OMIM = | MedlinePlus = 001263 | eMedicineSubj = orthoped | eMedicineTopic = 495 | MeSH =D056304 }} * [http://www.nhs.uk/Conditions/Knock-knee/Pages/Treatment.aspx Treating knock knee] {{Webarchive|url=https://web.archive.org/web/20160108113337/http://www.nhs.uk/Conditions/Knock-knee/Pages/Treatment.aspx |date=2016-01-08 }} - UK NHS
{{Congenital malformations and deformations of musculoskeletal system}}
Category:Medical conditions related to obesity Category:Congenital disorders of musculoskeletal system Category:Knee injuries and disorders