summary Genu Valgum is a normal physiologic process in children which may also be pathologic if associated with skeletal dysplasia, physeal injury, tumors or rickets. Diagnosis is made clinically with presence of progressive genu valgum after the age of 7. Treatment is observation for genu valgum <15 degrees in a child <7 years of age. Surgical management is indicated for severe and progressive genu valum in a child > 7 years of age. Epidemiology Incidence common but true incidence unknown Demographics most common age of presentation 3-5 years range 2-8 yrs Anatomic location distal femur is the more common location of pathological deformity Risk factors prior infection or trauma vitamin D deficiency/rickets obesity skeletal dysplasia lysosomal storage diseases Etiology Pathophysiology physiologic progression of coronal alignment genu varum <2 years of age neutral alignment around 2 years genu valgum will peak at 3-4 years to a tibiofemoral angle of 15-20 degrees genu valgum rarely worsens after age 7 login to view 2 more bullets lateral deviation of mechanical axis decreased growth from lateral physis relative to medial physis patellar instability increased Q-angle shallow lateral femoral sulcus login to view 1 more bullet Associated conditions bilateral genu valgum physiologic renal osteodystrophy (renal rickets) skeletal dysplasia login to view 3 more bullets unilateral genu valgum physeal injury from trauma, infection, or vascular insult proximal metaphyseal tibia fracture login to view 1 more bullet benign tumors login to view 3 more bullets fibular hemimelia Anatomy Osteology knee normal lateral distal femoral angle (LDFA) = 85-90 degrees normal medial proximal tibia angle (MPTA) = 85-90 degrees hypoplastic lateral femoral condyle with shallow lateral femoral sulcus Ligament medial collateral ligament 2 components login to view 5 more bullets may be attenuated in genu valgum Tendon increased combined lateral vector of quadricep and patellar tendon (increased q-angle) predispose to patellar instability Nerves common peroneal nerve branch off sciatic nerve that winds laterally around fibular neck bifurcates into two branches login to view 4 more bullets Biomechanics mechanical axis center of femoral head to center of ankle should pass through center of knee lateral deviation of mechanical axis in genu valgum login to view 1 more bullet mechanical loading on physis modulates growth Hueter–Volkmann law login to view 2 more bullets greater proportion of change in growth rate from hypertrophic zone (75%) than proliferative (25%) login to view 1 more bullet classification No uniform classification unilateral vs bilateral based on underlying etiology DIFFERENTIAL DIAGNOSIS Physiologic genu valgum must be differentiated from pathologic causes physiologic apparent obesity resulting in large thighs excessive femoral anteversion excessive external tibial torsion idiopathic post-traumatic Cozen phenomenon malunion physeal arrest metabolic renal osteodystrophy hypophosphatemic rickets infection osteomyelitis neuromuscular poliomyelitis neoplastic multiple hereditary exostoses fibrous dysplasia osteochondromas lysosomal storage disease mucopolysaccharidosis type IV (Morquio) skeletal dysplasia Chondroectodermal dysplasia (Ellis-van Creveld) Spondyloepiphyseal dysplasia tarda Pseudoachondroplasia Focal Fibrocartilaginous dysplasia PRESENTATION History medical and family history can help differentiate between physiological and pathological etiology Symptoms cosmetic deformity most common complaint often asymptomatic medial sided knee pain Physical exam abnormal circumduction gait inspection hip adduction medial aspect of knees touching wide intermalleolar distance (>8 cm) leg lengths range of motion assess patellar tracking rotational profile apparent genu valgum with excessive femoral anteversion or external tibial torsion general exam to assess stigmata of associated conditions rickets syndromic features skeletal dysplasias Maffucci syndrome IMAGING Radiographs indication asymmetrical findings excessive genu valgum clinically age group beyond which is expected of physiologic changes short stature history of trauma or infection limb length discrepancy views AP standing long-length film login to view 1 more bullet findings lateral deviation of mechanical axis through knee physeal narrowing or premature closing Park-Harris lines CT or MRI rarely indicated evaluate underlying malignancy evaluate for physeal bar STUDIES lab studies depends on suspected underlying medical conditions rickets login to view 3 more bullets mucopolysaccharidoses login to view 1 more bullet syndromic login to view 1 more bullet TREATMENT Nonoperative indications first line treatment tibiofemoral angle <15 degrees children <7 years of age modalities observation and medical management bracing login to view 1 more bullet outcomes vast majority of physiological genu valgum will resolve spontaneously medical management of underlying etiology may slow progression bracing may provide temporary relief but is an ineffective long-term solution Operative indications tibiofemoral angle > 15 degrees intramalleolar distance of 10 cm after age 10 years rapidly progressive deformity after age of 7 modalities medial hemiepiphysiodesis login to view 2 more bullets osteotomy login to view 2 more bullets outcomes eight-plate hemiepiphysiodesis login to view 2 more bullets rate of correction with hemiepiphysiodesis is variable login to view 2 more bullets TECHNIQUE Observation techniques observation and reassurance Medial hemiepiphysiodesis indications > 15-20° of valgus in a patient between ages 7-10 if line drawn from center of femoral head to center of ankle falls in lateral quadrant of tibial plateau in patient > 10 yrs of age options temporary hemiepiphysiodesis login to view 3 more bullets permanent hemiepiphysiodesis login to view 1 more bullet technique location of hemiepiphysiodesis dependent on 3 factors login to view 3 more bullets place extraperiosteally to avoid physeal injury implant placed midsagittal to avoid sagittal plane deformity one eight-plate or two staples per physis is generally sufficient postop login to view 6 more bullets complications (~5-10%) screw loosening or failure rebound deformity after removal infection premature physeal closure Osteotomy indications insufficient remaining growth to correct deformity with hemiepiphysiodesis skeletally mature patients non-functional growth plate (ie presence of bar, infection etc) options lateral distal femur opening wedge osteotomy login to view 6 more bullets medial distal femur closing wedge osteotomy login to view 6 more bullets high tibial osteotomy technique determining site of osteotomy login to view 3 more bullets complications nonunion neurovascular complication compartment syndrome hardware failure complications Peroneal nerve injury risk factors opening wedge technique prevention perform a peroneal nerve decompression at the time of surgery prior to distraction login to view 3 more bullets gradual correction of severe deformities can be done with circular external fixator Nonunion risk factors opening wedge osteotomy >20 deg deformity Limb length discrepancy closing wedge osteotomy shortens limb opening wedge osteotomy lengthens limb Undercorrection insufficient physeal growth or encroaching maturity Overcorrection lost to follow-up (12%) Rebound phenomenon incidence 56% defined as a loss of 5 degrees of correction once the plate is removed risk factors femoral deformity younger age at plate application and removal faster correction rate intentional overcorrection increased risk treatment consider slight overcorrection prior to implant removal login to view 1 more bullet consider performing growth modulation closer to skeletal maturity for milder deformities Physeal closure very rare (<1%) prevention place implant extraperiosteally remove implant with 2-3 years after insertion Prognosis Idiopathic genu valgum has a better prognosis than pathological etiology with hemiepiphysiodesis higher rate of complete correction faster correction rate fewer complications Physiologic genu valgum resolves spontaneous in vast majority by age of 7 Deformity after a proximal metaphyseal tibia fracture (Cozen) should be observed as most remodel maximum magnitude of deformity reached approximately 12-18 mo after injury resolve spontaneously within 2-4 years Threshold of deformity that leads to future degenerative changes is unknown