import { HighYieldBox, ExamCheatSheet, Tabs, Tab, ComparisonTable, VivaScenario, ContentSection, SpecialTestCard , MedicalImage} from '@/components/content' # Knee Osteoarthritis Examination Knee OA examination requires systematic assessment of alignment, compartmental involvement, and functional status. Examiners expect you to identify the pattern of arthritis (medial, lateral, or patellofemoral), assess severity, and evaluate the patient's suitability for different treatment options. ## Quick Reference One-Pager ## Classification and Patterns **Tibiofemoral OA:** - **Medial compartment**: Most common (60%), associated with varus - **Lateral compartment**: Less common (15%), associated with valgus - **Both compartments**: Pan-articular **Patellofemoral OA:** - Anterior knee pain - Worse with stairs and rising - May be isolated or combined - Common after patella fracture or instability **Tricompartmental OA:** - All three compartments affected - Usually requires TKR **Alignment and Arthritis:** - Normal tibiofemoral angle: 5-7° valgus - **Varus (bow-legged)** → Medial compartment overload → Medial OA - **Valgus (knock-knee)** → Lateral compartment overload → Lateral OA Alignment determines which compartment wears first and guides treatment options. ## Observation **Front View:** - Overall alignment (varus/valgus) - Quadriceps wasting (VMO especially) - Knee swelling (synovitis, effusion) - Scars from previous surgery **Lateral View:** - Fixed flexion deformity (FFD) - Hyperextension (recurvatum) - Patella position (alta/baja) **Behind (With Patient Walking):** - Varus/valgus thrust - Popliteal swelling (Baker's cyst) - Gait pattern **Clinical Assessment (Standing):** - Have patient stand with feet together - Observe tibiofemoral angle - Note if knees touch (valgus) or ankles touch (varus) **Inter-condylar Distance:** - Varus: Measure distance between knees when ankles together **Inter-malleolar Distance:** - Valgus: Measure distance between medial malleoli when knees together **Weight-Bearing Assessment:** - Mechanical axis: Hip center to ankle center - Should pass through knee center ## Gait Analysis **Antalgic Gait:** - Shortened stance phase on affected side - Reduces weight-bearing time **Varus Thrust:** - Lateral thrust of knee during stance - Indicates lateral ligament laxity or medial bone loss - Important prognostic finding **Valgus Thrust:** - Medial thrust (less common) - Indicates medial ligament laxity **Trendelenburg:** - May occur if hip also affected - Distinguish from knee pathology **Stiff Knee Gait:** - Reduced knee flexion in swing phase - Compensatory hip hiking or circumduction ## Palpation **Bony Landmarks:** - Joint line tenderness (medial vs lateral) - Osteophytes (palpable around joint margin) - Tibial tubercle **Effusion Assessment:** - Cross-fluctuance (moderate effusion) - Patella tap/ballottement (large effusion) - Bulge sign (small effusion) **Temperature:** - Warmth suggests active inflammation - Cool joint = less active disease **Patellofemoral:** - Tenderness around patella edges - Retropatellar crepitus ## Range of Motion **Extension:** - Normal: 0° (some hyperextension 5-10° is normal) - Fixed flexion deformity (FFD): Cannot reach 0° - Document degree of FFD (e.g., "15° FFD") **Flexion:** - Normal: 135-140° - Functional minimum for stairs: 90° - Functional minimum for sitting: 90-110° **Assessment Technique:** - Active then passive - Compare with contralateral - Note crepitus during movement - Note endpoint (hard/soft) **Record as:** 0° to 130° (normal) or 15° to 110° (FFD to max flexion) **Functional ROM Requirements:** - Walking on flat: 65-70° flexion - Climbing stairs: 85-90° flexion - Sitting comfortably: 95-105° flexion - Tying shoelaces: 105-110° flexion - Deep squatting: 130-140° flexion A patient with 0-90° ROM can walk and climb stairs but may struggle with deep bending. ## Ligament Stability **Why Important in OA:** - Ligament laxity affects alignment - Affects choice of implant (constrained vs unconstrained) - Varus/valgus laxity may indicate bone loss **Tests:** - **Varus stress (0° and 30°)**: Lateral ligament complex - **Valgus stress (0° and 30°)**: Medial ligament complex - **Lachman and anterior drawer**: ACL (less relevant unless history of instability) - **Posterior drawer**: PCL **Correctable vs Fixed Deformity:** - Correct varus/valgus with stress - Fixed = bony deformity/contracture - Correctable = ligament laxity +/- soft tissue ## Patellofemoral Assessment **Observation:** - J-sign (lateral tracking) - Patellar tilt or lateral displacement **Palpation:** - Tenderness around patella facets - Retropatellar crepitus with ROM **Functional:** - Pain worse descending stairs (eccentric load) - Pain with prolonged sitting (movie sign) - Pain rising from chair (high PF load) ## Functional Assessment **Gait Assessment:** - Walking distance (meters or blocks) - Need for walking aids - Limp pattern **Stairs:** - Can they ascend/descend normally? - Need for handrail? - Step-over-step vs step-to-step? **Rising from Chair:** - Can they rise without arm support? - Need to push up from armrests? **ADLs:** - Cutting toenails (flexion) - Getting in/out of car - Footwear (tying laces) **Document Pain:** - Location (medial, lateral, anterior, posterior) - Severity (VAS score) - Night pain (indicates severe disease) - Starting pain (after rest) - Walking pain ## Severity Assessment ## Treatment Considerations **Conservative Treatment Indicators:** - Mild symptoms - Good ROM - Minimal deformity - Correctable alignment **Osteotomy Consideration (HTO/DFO):** - Younger patient (less than 60) - Unicompartmental disease - Correctable deformity - Intact ligaments - Good ROM **Unicompartmental Knee Replacement:** - Single compartment disease - Correctable deformity (less than 15°) - Intact ACL - Range 90°+ flexion - No inflammatory arthritis **Total Knee Replacement:** - Tricompartmental disease - Severe symptoms - Failed conservative treatment - May have deformity, instability ## Summary Presentation ## Examiner Tips