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KNEE EXAMINATION
Tips & Tricks from an Emergency Physicianro E erge
Perspective
Dr P O’CONNOR
Emergency Medicine Physician
EUSEM
EM Physicians Less Exposed to MSK Medicine
- Musculoskeletal Medicine becoming the ‘Poor relation’ of EM
- Emphasis on Acute medicine and Critical care
- Knee Examination poorly taught/mastered at Medical School
- GPs not confident about knee examination/diagnosis
- Orthopaedics no longer part of many EM training Schemes
- Low threshold for referring undiagnosed knee problems to orthopaedics
- NPs and ESPs now look after much of Musculoskeletal Medicine
- Younger EM physicians less exposure to acute knee assessment- at risk of ‘losing skills’
Knee Anatomy
Anterior Knee Posterior Knee
Lateral Ligament
HISTORY
Mechanism of injury is vitally important
- Flexed/Twisting
- Forced flexion/Hyperextension
- Falls/Direct Blow
- Swelling Rapid/Gradual
- Previous Knee Problems
- Sports injury - Able to play on?
A Focussed History often reveals the Diagnosis
Surface Anatomy
Palpation Medially - R knee (^) Palpation Laterally – R knee
Abnormal bulges Popliteal artery aneurysm Popliteal thrombophlebitis Baker’s cyst
Palpation Posteriorly –Popliteal Fossa
Don’t Forget Pes Anserinus Bursitus!
Focused History Questions
Injury-Associated Events
Pop heard or felt?
- Swelling after injury (immediate vs delayed)
- Catching / Locking
- Buckling / Instability (“giving way”)
- Unable to play on
Aggravating / Relieving Factors
- Activities, changing positions, stairs, kneeling
- Treatments tried Ice, medications, crutches
- History of previous knee injury or surgery
Knee Examination
Adequate Exposure – Supine Position Compare both knees
Look Wasting,swelling,deformity redness,scars,local trauma, patella position
Feel Temp,Effusion,crepitus
Move Passive, Active Resting position, SLR, Extension,flexion,collateral ligaments, cruciates menisci
Only Examine the knee in the Supine Position
Knee Examination
AALWAYS CHECK THE HIP FIRST
- Especially in the young knee pain may be referred from the hip
- Roll the leg if comfortable
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“ Locked” Knee
Full extension blocked. Degree of which can vary. Possible meniscal injury. X-ray for loose body. Usually Requires MRI and possible arthroscopy.
Knee Referral Advice
LOCKED KNEES ARE AN EMERGENCY
WHY??
One chance to repair meniscus in under 30s
Do not let patients Weight Bear –Urgent Ortho Referral
Collateral Ligament Injury
Examination
Tenderness, stress testing
in flexion
Grading
Grade I Local tenderness+slight or no laxity
Grade II Local tenderness+laxity with endpoint. Orthopaedic follow up Complete rupture No endpoint. POP cylinder or brace. Analgesia, Crutches. Orthopaedic referral
Medial & Lateral Ligament Testing
Use a standard exam routine Direct, gentle pressure No sudden forces
Abnormal test
- Excessive motion = laxity
- Soft/mushy end point
When testing collateral ligaments make sure the knee is not straight as inherent joint & ACL stability will mask ligament instability (30 degrees flexion)
When assessing for MCL injury after valgus force and applying valgus force to knee- if pt has lateral and medial knee pain think? Tibial plateau fracture
Three out of 4 ligament laxity think occult knee dislocation (caution high BMI)
Tests For Meniscal Injury
- Joint Line Tenderness Sens 76% Spec 29%
- McMurray Test Sens 52% Spec 97%
Tests for ACL Assessment
Lachman’s, Anterior Draw and Lellie’s/Lever Test
If the pt has a large knee and you have small hands use your own knee to support/stabilise the back of the pt’s knee for Lachman’s test
Anterior Draw
Lachman’s
ACL Assessment
- Lever (Lelli) Test – high interrater reliability, most specific. Positive Lever Sign – Ruptured ACL
- Lachman’s Test
- Anterior Draw
- Pivot Shift
Tibial Sag = PCL Rupture
Beware missing PCL/Posterior sag due to large haemarthrosis
Tibial Tubercle normally Anterior to Patella on lateral view, Ski Jump Sign.
Haemarthrosis can be managed by Knee Aspiration & LA Injection
Inject 10-20 mls of chirocaine into knee for effective pain relief and ability to re-examine knee
Floating Patella
KNEE ASPIRATION
- Use Venflon cannula if possible as allows comfortable aspiration of
large volumes
- Look at aspirate and send to bacteriology lab if not a
lipohaemarthrosis
- Fluid Level on Lateral Xray
**Lipohaemarthrosis (Blood and Fat)
FRACTURE**
AAspiration from the Lateral side easier
Questions?
Summary
- Focussed History is the key to accurate assessment of the acute
knee
- Comprehensive examination and appropriate investigations should
confirm the diagnosis
- Accurate timely Emergency Department Assessment leads to better
patient outcomes
- Competent Knee Examination is mandatory for ED physicians
- Keep Teaching the juniors!
