How should a comprehensive knee assessment be performed?

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Comprehensive Knee Assessment

A comprehensive knee assessment should begin with radiography (anteroposterior and lateral views) as the initial imaging modality for patients meeting Ottawa or Pittsburgh rule criteria, followed by a systematic physical examination evaluating alignment, range of motion, effusion, ligamentous stability, meniscal integrity, and neurovascular status. 1

Clinical History Components

The history must capture specific elements that guide subsequent evaluation:

  • Pain characteristics: Location (medial, lateral, anterior, diffuse), onset (acute vs. chronic), duration, and quality 2, 3
  • Mechanical symptoms: Locking, popping, catching, or giving way suggest internal derangement 2, 3
  • Swelling pattern: Timing of effusion development (immediate suggests hemarthrosis from fracture or ligament tear; delayed suggests inflammatory process) 3
  • Trauma mechanism: Direct blow, twisting injury, hyperextension, or dashboard injury patterns 1, 2
  • Functional limitations: Inability to bear weight or flex to 90 degrees are critical Ottawa rule criteria 1
  • Age considerations: Patients >55 years warrant radiographs even without other positive findings per Ottawa rules 1
  • Prior knee injury or surgery: Suggests early osteoarthritis development 4

Physical Examination Algorithm

Inspection

  • Alignment assessment: Varus or valgus deformity using goniometer (reliability coefficient 0.99) 5
  • Gait observation: Antalgic patterns, inability to bear weight 5
  • Quadriceps atrophy: Visual comparison between limbs (reliability coefficient 0.97) 5
  • Gross deformity: Mandates immediate radiography regardless of clinical rules 1

Palpation

  • Bony tenderness: Patella, fibular head, tibial plateau, femoral condyles (reliability coefficient 0.94-0.97 for medial/lateral tibiofemoral tenderness) 1, 5
  • Joint line tenderness: Medial and lateral compartments for meniscal pathology 4, 3
  • Bony swelling: Osteophyte formation (reliability coefficient 0.97) 5
  • Warmth: Though poorly reliable (PABAK 0.14), assess for infection or acute inflammation 5

Effusion Assessment

  • Bulge sign: Highly reliable test (reliability coefficient 0.97) for detecting small effusions 5
  • Ballottement: For moderate to large effusions 3
  • Cross-table lateral radiograph: Visualizes lipohemarthrosis indicating intra-articular fracture 1

Range of Motion

  • Flexion contracture measurement: Highly reliable (reliability coefficient 0.95) 5
  • Active and passive flexion: Inability to flex to 90 degrees is an Ottawa rule criterion 1
  • Crepitus assessment: Patellofemoral and general passive crepitus (reliability coefficient 0.96) 5

Ligamentous Testing

  • Anterior/posterior drawer tests: ACL and PCL integrity 3, 6
  • Valgus/varus stress testing: Medial and lateral collateral ligament stability, though reliability is poor (PABAK 0.02-0.34 for instability testing) 5
  • Lachman test: More sensitive than drawer for ACL tears 3

Meniscal Testing

  • McMurray test: Rotation with flexion-extension, though may cause pain in osteoarthritis patients with degenerative tears 4, 3
  • Joint line tenderness: Correlates with meniscal pathology 3

Neurovascular Assessment

  • Popliteal pulse palpation: Essential in high-energy trauma or suspected dislocation 2, 3
  • Peroneal and tibial nerve function: Motor and sensory testing 1

Imaging Decision Algorithm

Initial Radiography Indications

Obtain radiographs if ANY of the following Ottawa rule criteria are met: 1

  • Age >55 years
  • Isolated patellar tenderness (no other bony tenderness)
  • Tenderness at fibular head
  • Inability to flex knee to 90 degrees
  • Inability to bear weight (four steps) both immediately and in emergency department

Standard radiographic views: 1

  • Anteroposterior view
  • Lateral view at 25-30 degrees flexion (lateral decubitus position, patella in profile)
  • Cross-table lateral with horizontal beam for lipohemarthrosis
  • Patellofemoral view for suspected patellar fracture/dislocation

Exceptions to Clinical Decision Rules

Obtain radiographs immediately regardless of Ottawa/Pittsburgh criteria if: 1

  • Gross deformity present
  • Palpable mass
  • Penetrating injury
  • Prosthetic hardware
  • Multiple injuries affecting reliability of examination
  • Altered mental status (head injury, intoxication, dementia)
  • Neuropathy (paraplegia, diabetes)
  • Age 5-12 years (falls outside both rule age ranges)

Advanced Imaging Indications

MRI without IV contrast is indicated when: 1

  • Radiographs normal but pain persists with suspected occult fracture or internal derangement
  • Radiographs show joint effusion but no fracture
  • Suspected ligamentous injury (ACL, PCL, collateral ligaments)
  • Suspected meniscal tear requiring surgical planning
  • Bone marrow lesions or subchondral insufficiency fractures suspected

CT is indicated when: 1

  • Superior fracture characterization needed (tibial plateau fractures show 100% sensitivity vs. 83% for radiographs)
  • Patellofemoral anatomy evaluation for maltracking
  • MRI contraindicated

CTA lower extremity is indicated when: 1

  • Knee dislocation with suspected vascular injury (30% incidence with posterior dislocation)
  • Absent or diminished pulses
  • Expanding hematoma

Chronic Knee Pain Considerations

For chronic pain (>6 weeks), radiography remains the initial study: 1

  • Include frontal projection (AP, Rosenberg, or tunnel view), tangential patellar view, and lateral view 1
  • Approximately 20% of chronic knee pain patients undergo MRI without recent radiographs, which is inappropriate 1

Consider referred pain sources if knee radiographs unremarkable: 1

  • Hip radiographs for ipsilateral hip pathology
  • Lumbar spine radiographs for radicular symptoms

Critical Pitfalls to Avoid

  • Do not skip radiographs in patients >55 years even without focal tenderness or effusion 1
  • Do not apply clinical decision rules to patients with altered mental status, neuropathy, or multiple injuries 1
  • Do not order MRI as initial study in acute trauma or chronic pain without recent radiographs 1
  • Do not dismiss meniscal tears as pain source in elderly: >70% have asymptomatic tears, making clinical correlation essential 1
  • Do not rely on instability testing alone: Medial and lateral instability testing at 30 degrees has very poor reliability (PABAK 0.02-0.34) 5
  • Recognize vascular emergency: Knee dislocation requires immediate vascular assessment with CTA given 30% popliteal artery injury rate 1

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

4
Research

Clinical Evaluation of the Knee Arthritis Patient.

Techniques in vascular and interventional radiology, 2023

6
Research

Physical examination of the knee.

Primary care, 2004

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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