10/5/2015
The Approach to Acute Knee Effusions
ASAPA 2015 Fall Conference Kevin Cantwell, PA-C, Ortho CAQ FastMed Sports Medicine
What the EFF(usion)?!
Do I Aspirate or not?
Do I get an MRI?
Do I send to the ER?
Overview
Discuss Pertinent History
Review Anatomy
Focused, effective physical exam
Review of Aspiration Technique
Laboratory Evaluation
1 10/5/2015
Causes
Traumatic/Hemorrhagic
Patellar Dislocation, ACL tear, fracture
Inflammatory
Gout, Pseudogout, Rheumatoid
Infectious
Non-inflammatory
HPI
Injury Mechanism: ie. Direct blow, deceleration, valgus injury, prolonged squatting/twisting Pain versus No Pain
Prior history: ie. Gout, patellar instability, arthritis
Surgical history: arthroscopic/open
Associated symptoms: ie. Polyarthritis, Fever, Conjunctivitis, urethral discharge
History
Trauma
Fracture: Direct blow, age >55yo, inability to walk
ACL: non-contact deceleration, cutting movement or hyperextension
Meniscus: squatting/twisting, mechanical symptoms
Collateral sprain:
Patellar Dislocation: twisting force on weight bearing leg
Fracture, ACL and Patellar Dislocation: 35-60% cause of hemarthrosis within 4 hours
2 10/5/2015
Knee Anatomy
Physical Exam
General Appearance (WB/distressed?) Skin: erythema/wounds/warmth Deformity/Guarding/Splinting Active ROM/ Passive ROM (hip, knee, ankle) Straight Leg Raise Popliteal angle Palpation: Suprapatellar fullness/fluctuance, medial patellar fullness Patellar Mobility, Apprehension, Facet Pain Quad tendon or Patellar tendon defect/pain Joint line pain McMurrays
Physical Exam
Should I bend the knee?
Can the patient bend the knee?
Perform Straight Leg Raise (SLR)?
3 10/5/2015
Physical Exam
Recognizing an Effusion
Suprapatellar fullness
Medial peripatellar fullness (VMO may look enlarged)
Popliteal Angle: resting position 15-25 degrees
Effusion versus Bursitis
Effusion versus Bursitis
4 10/5/2015
Physical Exam(cont.)
Ligament Exam
MCL: valgus stress in full extension and at 30 degrees of flexion
LCL: Varus stress
PLC: External Dial, ER recurvatum
PCL: Sag sign and posterior drawer
ACL: Anterior Drawer (least reliable) Pivot Shift Lachmans (best for ACL laxity)
Physical Examination
Always compare to the contralateral leg
Best in supine position
Tailor the exam to the patient
5 10/5/2015
Imaging
X-rays:
AP Standing
AP Weightbearing/Tunnel/ Intercondylar
Lateral
Merchant/Sunrise
Oblique
Imaging
Magnetic Resonance Imaging
Safe
Painless (most of the time)
Precise
Cost effective?
Expensive
No contrast needed (unless knee effusion with history of meniscus repair)
Aspiration
Synovial analysis is sensitive and inexpensive
Crystalline arthropathies readily identified
Gram stain and culture are diagnostic of infection
Alleviates acute symptoms and improves joint mobility
Few contraindications
6 10/5/2015
Aspiration
Indications
Septic joint
Crystalline arthropathy
Hemorrhagic (trauma/coagulopathy)
Chronic arthritis (OA, RA) Contraindications
Overlying ulcer/wound
Suspected Tumor?
Coagulopathy
Aspiration
Technique
Supine
Popliteal Bump
Betadine, Ethyl Chloride, Alcohol
18-gauge needle with 30-60 cc syringe
Aspiration site is provider preference
Aspiration
7 10/5/2015
Acute Effusion Labs
Synovial Fluid Cell Count Crystals Gram Stain Culture Glucose (decreased with RA, infection) Protein (elevated with RA) Blood CBC with differential ESR, CRP RA work up: RF, ANA, anti-CCP,
Synovial Analysis
Baker K.
ACL tear
History of deceleration, cutting or hyperextension injury Typically large effusion Positive lachmans, anterior drawer or pivot shift Xrays typically negative. Possible tibial spine avulsion or lateral Segond fracture Aspirate for pain relief Crutches, hinged-knee brace, ice, encourage ROM MRI Ortho Referral
8 10/5/2015
Gout/Pseudogout
Similar to Septic joint Assoc’d with hyperuricemia/hyperparathyroid, hemochromatosis, hypothyroid Monosodium Urate crystals/Calcium Pyrophosphate Previous history (first attack 40-50 yo) High-Purine diet, Diuretic use, increase Etoh = Gout Xrays: Chondrocalcinosis with pseudogout Serum Uric acid may or may not be elevated Tx: Colchicine, Indomethacin (NSAIDs), Consider injection if not septic
Inflammatory
Rheumatoid Arthritis, SLE, Reactive Arthritis Worse in the morning Better with activity Multiple joints Rash/conjunctivitis/urethritis Xrays: marginal erosions and osteopenia Labs: CRP/ESR/RF/ANA/anti-CCP/HLA-B27
Aspirate: decrease glucose , elevated protein Refer
Septic Arthritis
Red, hot, swollen knee Knee effusion Fever, chills Severe pain, exacerbated with ROM History/Risk factors: DM, RA, Lupus, HIV, steroid use, immunocompromised, IV drug use, surgery Xrays: no acute findings Refer to ER, Call Ortho for I and D Aspirate/Labs: cloudy, WBC >50,000, PMNs >75-90%, + gram stain/cx
9 10/5/2015
Patella Dislocation
Twisting force on weight bearing leg Recurrence rate is low after first time dislocation Usually painful Large effusion, peripatellar/medial knee pain Apprehension Aspiration for relief, fat droplets indicate intra-articular fracture Xrays: Osteochondral fracture of medial facet or lateral trochlea; trochlear dysplasia; patella alta MRI: Evaluates for osteochondral fracture Tx: Crutches, patellar stabilizing brace. No OC fx->PT Ortho referral
Osteoarthritis
Pain with use, relief with rest
PF: pain with prolonged sitting Previous exacerbations History of trauma Effusion, erythema and warmth with exacerbations Pain much less and ROM much better compared to Septic Joint Xrays: joint space narrowing, osteophyte formation Aspirate: clear, <200WBC, <25% PMNs Activity modification, NSAIDs, Injections
Peds
Well Child
With History of Without Trauma significant trauma
Mechanical Bleeding Fractures Derangements Disorders/Neoplasia
10 10/5/2015
Peds
Sick Child
Febrile Afebrile
Partially treated Acute Rheumatic Sepsis Septic Arthritis Fever Malignancy Kawasaki Disease Sickle Cell Connective Tissue Disorder
Resources
X-Rays Views
11 10/5/2015
Alogrithm
Synovial Analysis
Baker K.
Differential
Miller Orthopedics
12 10/5/2015
Differential
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