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• Antalgic gait or avoidance gait due to fear of giving way
• Toe-out gait (increased foot progression angle) suggesting external tibial torsion
• Trendelenburg gait if associated hip abductor weakness

• Knee held in slight flexion to avoid quadriceps contraction
• Leg may be externally rotated
• If currently dislocated: patella visibly displaced laterally, knee held in slight flexion

• General findings: Overlying skin - bruising/ecchymosis after acute episode, swelling (hemarthrosis), old scar if previously operated, sinus if infected
• Specific findings of inspection:
  a. From front:
  • Deformity: Genu valgum (most common predisposing factor), increased Q angle
  • Muscle wasting: Vastus medialis obliquus (VMO) wasting prominently
  • Position of patella: Patella alta (high-riding patella), lateral tilt of patella, "grasshopper eye" appearance (bilateral lateral displacement)
  • Limb length discrepancy
  • Supra/parapatellar swelling (hemarthrosis or effusion)
  • Pelvis position and ankle-foot: Pes planus, pronated foot, increased femoral anteversion
  b. From side:
  • Sagittal plane deformity: Patella alta visible as high-riding patella
  • Flexion deformity if acute episode
  • Genu recurvatum (associated with ligamentous laxity)
  c. From back:
  • Popliteal fossa - any swelling
  • Spine - scoliosis if associated
  • Calf muscle wasting
  • Ankle-foot deformity (pes planus)

• Local rise in temperature (if acute/recent dislocation)
• Tenderness:
  • Medial retinaculum tenderness (torn MPFL - medial patellofemoral ligament)
  • Lateral retinaculum tenderness
  • Medial femoral condyle tenderness (MPFL femoral attachment)
  • Lateral patellar facet tenderness
  • Anterior knee tenderness
• Joint line tenderness (associated chondral damage)
• Patellar tap - effusion/hemarthrosis
• Crepitus on patellar movement (chondromalacia patellae)
• Synovial hypertrophy
• Retropatellar tenderness (patella-facet grinding)
• Hyperlaxity of joints (generalised ligamentous laxity - Beighton score)
• Confirmation of palpatory characteristics of swelling, scar, sinus, and deformities

• Flexion-extension range: usually full unless acute episode
• Extensor lag (if VMO weak or acute injury)
• Flexion deformity
• Patellar tracking during active flexion-extension: J-sign (patella jumps laterally at terminal extension - pathognomonic of recurrent dislocation)
• Crepitus, clicks during movement

• Limb length and thigh-calf circumference (VMO wasting quantified)
• Q angle: Increased (>15° in females, >10° in males) - most important measurement
• Intercondylar and intermalleolar distance (for genu valgum assessment)
• TT-TG distance (tibial tubercle to trochlear groove) - radiological, normal <20 mm
• Patellar height ratio (Insall-Salvati ratio) - for patella alta

• Distal pulses (dorsalis pedis, posterior tibial)
• Sensation over anterior knee, medial and lateral aspects
• Peroneal nerve assessment (foot dorsiflexion, first web space sensation)

• Apprehension test (Clarke's sign): With knee at 30° flexion, examiner pushes patella laterally - positive if patient apprehends or contracts quadriceps in fear of dislocation (pathognomonic)
• Quadrant test: Patella displaced medially and laterally to assess retinacular tightness - lateral retinaculum tightness noted
• Patellar horizontal tilt test: Medial edge of patella cannot be elevated beyond neutral - indicates tight lateral retinaculum
• Patellar glide test: Patella displaced >2 quadrants laterally indicates MPFL laxity
• Patellar tracking: J-sign during active knee extension
• Fulkerson tilt test: Assess patellar tilt
• Beighton score: For generalised ligamentous laxity

• Hip: Increased femoral anteversion (Craig's test), hip abductor weakness (Trendelenburg)
• Spine: Lumbosacral alignment
• Ankle-foot: Pes planus, subtalar pronation (increases Q angle dynamically)

• Inguinal lymphadenopathy (if infective etiology considered)

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• Trochlear dysplasia (flat/convex trochlea)
• Patella alta (Insall-Salvati >1.2)
• Increased TT-TG distance (>20 mm)
• MPFL insufficiency
• Increased Q angle / genu valgum
• Generalised ligamentous laxity
• VMO hypoplasia

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Clinical Assessment of Genu Varum and Genu Valgum

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Definitions

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Step 1 - Patient Position

• Patient stands barefoot, in light clothing, feet together (medial malleoli touching)
• Patellae facing forward (neutral rotation)
• Knees in full extension
• Examined from the front (AP view)

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Step 2 - Visual Inspection (Standing)

• Gap between the knees when feet/ankles are together
• Lower limbs appear bowed outward
• Feet may show lateral border loading / fallen pedal arch

• Gap between the ankles when knees are touching
• Lower limbs angle inward at the knee
• Associated pes planus, toe-out gait

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Step 3 - Clinical Measurement (Key Step)

A. Intercondylar Distance - For Genu Varum

• Ask patient to stand with medial malleoli together
• Measure the gap between the medial femoral condyles at the knee
• Use a tape measure or ruler between the most prominent medial condyle points
• Normal: condyles touch (0 cm)
• Abnormal: >3 cm is considered pathological

B. Intermalleolar Distance - For Genu Valgum

• Ask patient to stand with knees together (medial condyles touching)
• Measure the gap between the medial malleoli at the ankle
• Normal: malleoli touch (0 cm)
• Abnormal: >5 cm is considered pathological

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Step 4 - Mechanical Axis Assessment

• Normal: The mechanical axis (from center of femoral head to center of ankle) passes through the center of the knee. The femorotibial angle is 174° (a slight physiological valgus).
• Genu Varum: Center of knee joint is lateral to the mechanical axis - medial compartment overloaded
• Genu Valgum: Center of knee joint is medial to the mechanical axis - lateral compartment overloaded

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Step 5 - Q Angle Measurement

• Patient: Supine, quadriceps relaxed, knee in full extension
• Line 1: From ASIS (anterior superior iliac spine) to center of patella
• Line 2: From center of patella to tibial tubercle
• The angle between these two lines = Q angle

• Increased Q angle is associated with genu valgum and patellar instability
• Decreased/negative Q angle suggests genu varum

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Step 6 - Supine Examination

• Ask patient to lie supine, legs extended and relaxed
• Bring both knees together - confirm deformity persists (structural) vs disappears (postural/flexible)
• Check for fixed vs correctable deformity
• Assess whether deformity is symmetrical or asymmetrical

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Step 7 - Gait Assessment

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Step 8 - Associated Findings to Document

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Physiological (Normal) Age-Related Changes

Any deformity persisting or worsening beyond these age norms warrants investigation for rickets, Blount's disease, or metabolic bone disease.

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Summary - Quick Bedside Reference

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Q Angle - Precise Clinical Measurement

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What is the Q Angle?

• Line 1 (Proximal): From the Anterior Superior Iliac Spine (ASIS) to the center of the patella - represents the line of pull of the quadriceps muscle
• Line 2 (Distal): From the center of the patella to the tibial tubercle - represents the line of the patellar tendon

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Equipment Needed

• Standard long-arm goniometer (preferred)
• Skin marker/pen
• Measuring tape
• Patient in appropriate position (see below)

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Patient Positioning (Critical for Accuracy)

1. Patient supine on a flat examination table
2. Knee in full extension (0°)
3. Quadriceps relaxed (not contracted)
4. Hip in neutral rotation - patella facing directly upward
5. Feet in neutral position - not internally or externally rotated

Note: Hip rotation significantly affects the Q angle - internal rotation increases it, external rotation decreases it. Always ensure neutral hip position.

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Step-by-Step Measurement Technique

• Line from ASIS to center of patella
• Line from center of patella to tibial tubercle

• Fulcrum (center): Over the center of the patella
• Proximal arm: Aligned toward the ASIS
• Distal arm: Aligned toward the tibial tubercle

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Normal Values

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Why Q Angle is Higher in Females - Anatomy

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Common Errors to Avoid

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Q Angle in Standing vs Supine

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Clinical Significance of an Increased Q Angle

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Associated Radiological Measurement - TT-TG Distance

• TT-TG (tibial tubercle - trochlear groove) distance on CT or MRI
• Normal: <20 mm

• 20 mm: indication for tibial tubercle medialization (Fulkerson osteotomy)

• This is the radiological equivalent and more precise version of the Q angle