import { HighYieldBox, ExamCheatSheet, Tabs, Tab, ComparisonTable, VivaScenario, ContentSection, SpecialTestCard , MedicalImage} from '@/components/content' # Paediatric Lower Limb Alignment Examination Lower limb alignment examination in children requires understanding of normal developmental variation. Examiners expect you to differentiate physiological from pathological conditions, measure angular and rotational profiles, and know when investigation is warranted. ## Quick Reference One-Pager ## Normal Developmental Alignment **Normal Development:** - **Birth**: 10-15° varus (bow-legged) - **18 months**: Neutral alignment - **2-4 years**: Progressive valgus - **4 years**: Maximum valgus (up to 12°) - **7 years**: Adult alignment (5-7° valgus) **Key Point:** Most angular deformities in toddlers are physiological and will correct spontaneously. **When to Worry About Angular Deformity:** 1. **Varus persisting beyond age 2-3 years** 2. **Varus increasing after age 2** 3. **Unilateral or asymmetric deformity** 4. **Associated with short stature** 5. **Lateral thrust with walking** 6. **Intermalleolar distance greater than 8cm (valgus)** 7. **Intercondylar distance greater than 6cm (varus)** ## Examination Technique **Position:** - Child standing with knees facing forward - Feet slightly apart, patellae neutral - If possible, assess with knees extended **Varus (Bow-Legged) Assessment:** - Stand behind child - Bring medial malleoli together - Measure intercondylar distance (cm) - Normal: Up to 6cm in physiological varus age **Valgus (Knock-Knee) Assessment:** - Bring medial femoral condyles together - Measure intermalleolar distance (cm) - Normal: Up to 8cm at age 4 years ## Rotational Profile **Components of Rotation:** 1. **Femoral anteversion** (hip internal/external rotation) 2. **Tibial torsion** (thigh-foot angle) 3. **Foot shape** (metatarsus adductus/normal) **Foot Progression Angle (FPA):** - Angle of foot to line of progression during walking - Normal: 10° external (range: -3° to +20°) - Negative = in-toeing - Positive = out-toeing **Causes by Level:** **1. Metatarsus Adductus (Foot Level):** - Bean-shaped foot - Lateral border curved - Bisection of heel points lateral to 2nd toe - Usually resolves by 2 years **2. Internal Tibial Torsion:** - Negative thigh-foot angle - Normal: 0-20° external - In-toeing: Neutral or internal - Improves with walking **3. Femoral Anteversion:** - Increased internal rotation of hip - Decreased external rotation - "W-sitting" posture - Usually resolves by age 8-10 **Most Common:** 3-6 years = increased femoral anteversion **Causes by Level:** **1. External Tibial Torsion:** - Increased thigh-foot angle (greater than 30°) - Often with flat feet **2. Femoral Retroversion:** - Decreased internal rotation - Increased external rotation - Less common, may be pathological **3. External Rotation Contracture (Infant):** - Prenatal molding - Resolves spontaneously **Associated Conditions:** - SCFE (obligate external rotation) - Cerebral palsy - Slipped capital femoral epiphysis ## Leg Length Discrepancy **True vs Apparent LLD:** - **True LLD**: Actual bone length difference - **Apparent LLD**: Pelvic obliquity, contractures **Causes:** - Congenital: Hemihypertrophy, limb deficiency - Acquired: Trauma (growth plate injury), infection, Perthes - Neuromuscular: Polio, cerebral palsy **Clinical Significance:** - Less than 2cm: Often asymptomatic - 2-5cm: May need shoe raise - Greater than 5cm: Consider surgical equalization **Technique:** - Child supine, knees flexed, feet flat on bed - Compare height of knees **Interpretation:** - Unequal knee height = LLD - Lower knee on shorter side (femoral shortening) - Higher tibia on longer side (tibial shortening) **Limitation:** - Cannot distinguish femur from tibia discrepancy alone - Need individual bone measurements ## Specific Conditions **Blount's Disease (Tibia Vara):** - Progressive varus after age 2 - Due to growth disturbance of medial proximal tibial physis - **Infantile type**: 1-3 years, often bilateral, obese - **Adolescent type**: 8+ years, unilateral, obese - **Drennan angle greater than 16°** on X-ray = likely progressive - Treatment: Bracing (early), osteotomy (progressive) ## Gait Observation **Observe:** - Foot progression angle - Knee alignment during stance - Lateral thrust (suggests lateral compartment overload) - Trendelenburg (hip pathology) - Circumduction (LLD, stiff joint) **Running:** - May exaggerate rotational abnormalities - In-toeing often more apparent - Note any falls or clumsiness **Stairs (if age appropriate):** - Reciprocal pattern expected by 3-4 years - Difficulty may suggest weakness ## Summary Presentation ## Examination Sequence 1. **Observe standing**: Overall alignment, symmetry 2. **Measure angular**: Intercondylar or intermalleolar distance 3. **Observe gait**: Foot progression angle, lateral thrust 4. **Prone examination**: Hip rotation, thigh-foot angle 5. **Supine examination**: Hip ROM, Galeazzi test, foot shape 6. **Block test**: Leg length discrepancy if suspected 7. **Joint examination**: Knee, hip, ankle - stability and ROM 8. **General**: Height, features of syndromes, skin (cafe-au-lait) 9. **Compare sides**: Always look for asymmetry 10. **Document**: Measurements, diagram, comparison with normal values ## Examiner Tips