วันศุกร์ที่ 8 พฤษภาคม พ.ศ. 2569

Arthrocentesis & Intraarticular Glucocorticoid Injection

Arthrocentesis & Intraarticular Glucocorticoid Injection

Overview

Needle insertion into joint ทำเพื่อ:

1.       Arthrocentesis (diagnostic/therapeutic aspiration)

2.       Intraarticular injection

Most injections:

  • glucocorticoid
    ±
  • local anesthetic

INDICATIONS

1. Diagnostic Arthrocentesis

Most important indications

Suspected Septic Arthritis

ข้อสำคัญ:

septic arthritis ต้อง aspirate เสมอถ้าสงสัย

Especially important:

  • diabetic
  • immunocompromised
  • poor follow-up reliability

Important pearl

Septic arthritis:

coexist กับ gout/RA ได้

ดังนั้น:

  • culture
  • crystal analysis
    ควรทำพร้อมกัน

Timing

ควร aspirate:

BEFORE antibiotics

เพราะ antibiotics ทำให้:

  • synovial WBC ลดลง ~50%

2. Suspected Crystal Arthropathy

Gold standard diagnosis:

synovial crystal analysis

แม้:

  • US
  • DECT (dual-energy CT)
    ช่วยได้

แต่ aspiration ยัง preferred

Indications for Intraarticular Steroid Injection

Inflammatory arthritis

  • RA
  • PsA
  • spondyloarthritis
  • reactive arthritis

Crystal arthritis

  • gout
  • CPPD
  • BCP (Basic calcium phosphate crystal) arthritis

Osteoarthritis

Especially:

  • moderate-severe knee OA

RELATIVE CONTRAINDICATIONS

1. Septic arthritis

Absolute practical contraindication to steroid injection

2. Overlying cellulitis/periarticular infection

Risk:

  • inoculate infection into joint

3. Periarticular fracture

Steroid may impair bone healing

4. Planned arthroplasty

Important:

avoid steroid injection within 3 months before arthroplasty

Associated with:

  • ↑ PJI risk

5. Joint instability

Steroid may worsen:

  • ligament weakness
  • capsular laxity

6. Juxtaarticular osteoporosis

7. Repeated injections in OA

Repeated steroid injections:

  • diminishing benefit
  • possible cartilage toxicity

Important Point: Anticoagulation

Generally safe:

  • warfarin
  • DOACs
  • antiplatelet agents

Warfarin

Usually acceptable if:

  • INR ≤3–3.5

Unless:

  • septic joint suspected → proceed urgently

INFORMED CONSENT

Discuss:

  • infection
  • postinjection flare
  • facial flushing
  • bleeding
  • leakage
  • steroid adverse effects

Important risks

Septic arthritis

Rare:
~1/1000–3000 procedures

Postinjection flare

~5%

Can mimic infection

Facial flushing

Up to 10%

Usually not allergy

EQUIPMENT

Needle size

Standard

22G ideal for most joints

Larger needle (18–20G)

Use for:

  • large knee effusion
  • viscous pus
  • Baker cyst
  • thick synovial fluid

Needle length

  • small/medium joints → 1 inch
  • shoulder/knee → 1.5–2 inch
  • obese patient → longer

Syringe size

Preferred

5 mL often ideal

Large effusion

20–50 mL syringe

Important Pearl

Large syringe:

  • more resistance
  • harder to distinguish tendon injection

GENERAL PRINCIPLES OF NEEDLE ENTRY

Goals:

1.       easiest capsule access

2.       avoid neurovascular structures

3.       avoid skin lesions/infection

Needle:

bevel-up always

KNEE ARTHROCENTESIS (High-yield)

Preferred approaches

Suprapatellar approach

Best for:

  • large effusions

Parapatellar approach

Best for:

  • smaller effusions

Infrapatellar seated approach

Useful when:

  • wheelchair patient
  • cannot extend knee

Suboptimal for aspiration

Knee Position

Slight flexion:
15–20°

Key maneuver

Compression/manipulation:

increases aspiration success

HIP ASPIRATION

Usually:

image-guided only

Methods:

  • fluoroscopy
  • ultrasound

SHOULDER ASPIRATION

Anterior approach

Most commonly used

Posterior approach

Advantages:

  • less painful
  • patient doesn’t see needle

NO-TOUCH TECHNIQUE

Key principle:

avoid touching sterilized field

Sterile gloves not always necessary if proper no-touch technique used

Infection risk

Can reduce septic joint risk to:
<1/2000

SKIN PREPARATION

Preferred:

  • chlorhexidine
    or
  • iodine prep

Avoid:

alcohol alone

LOCAL ANESTHESIA

Lidocaine

  • 0.5–2 mL
  • along needle track

Disadvantage:

  • may reduce culture sensitivity

Ethyl chloride spray

Provides:
~15 sec anesthesia

Useful for:

  • quick skin puncture

JOINT ASPIRATION

Before steroid injection

Always visually inspect fluid

If fluid:

  • turbid
  • purulent
  • unexpectedly viscous

→ send:

  • Gram stain
  • culture
  • cell count

before steroid injection

Debulking Effusions

Benefits:

  • pain relief
  • ↓ chondrocyte damage
  • ↑ steroid effectiveness

Especially useful in:

  • RA knees
  • large tense effusions

Important Pearl

Aspiration before steroid injection:

lower relapse rate

SYNOVIAL FLUID STUDIES

Send when diagnosis uncertain:

  • cell count
  • differential
  • Gram stain
  • culture
  • crystal analysis

ULTRASOUND GUIDANCE

Indications

  • deep joints
  • obesity
  • difficult anatomy
  • failed aspiration (“dry tap”)
  • suspected septic joint

Particularly useful for

  • hip
  • shoulder
  • wrist
  • prosthetic joints

DRY TAP

Definition:

unable to aspirate fluid despite repositioning

Causes

1. Technical failure

Most common

2. Altered anatomy

  • prior surgery
  • deformity
  • trauma

3. Needle obstruction

  • synovium
  • plica
  • debris
  • viscous fluid

4. Small effusion

5. No actual effusion

Important Knee Dry Tap Causes

  • fat pad
  • plica
  • obesity

Approach to Dry Tap

1.       Change approach

2.       Compression maneuvers

3.       Ultrasound/fluoroscopy

Prosthetic Joint Pearl

Suspected septic prosthetic joint:

failed blind tap → urgent fluoroscopic-guided aspiration

Orthopedic emergency

JOINT LAVAGE

Usually:

NOT recommended

because:

  • dilutes sample
  • complicates interpretation

Possible role:

  • prosthetic joint infection
  • sternoclavicular septic arthritis

POST-PROCEDURE CARE

Advise:

  • decrease weightbearing 24–48 hr
  • ice
  • OTC analgesics
  • keep site clean

FOLLOW-UP

Depends on disease:

  • OA injection → months
  • inflammatory arthritis flare → shorter follow-up

ANTICOAGULATION PEARLS

Generally safe:

  • warfarin
  • DOACs

Bleeding complications:

very rare

High-yield Clinical Pearls

  • Septic arthritis and gout can coexist
  • Aspirate before antibiotics whenever possible
  • Crystal analysis remains gold standard for gout diagnosis
  • Avoid steroid injection if septic arthritis suspected
  • Avoid steroid injection within 3 months before arthroplasty
  • Large viscous effusions may require 18–20G needle
  • Aspiration before steroid injection improves outcomes
  • Dry tap does not exclude septic arthritis
  • Ultrasound greatly improves success in difficult joints
  • Prosthetic joint infection + failed blind tap = fluoroscopic-guided aspiration urgently
  • Debulking tense effusions improves pain and may protect cartilage
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Complications of Total Knee Arthroplasty (TKA)

Complications of Total Knee Arthroplasty (TKA)

ภาพรวม

TKA เป็น procedure ที่ effective และ relatively safe แต่ complications อาจรุนแรงถึง life-threatening ได้

Complications สำคัญ:

  • VTE/PE
  • infection/PJI
  • neurovascular injury
  • instability
  • aseptic loosening
  • arthrofibrosis

PERIOPERATIVE COMPLICATIONS

1. Blood Loss

ปัจจุบันลดลงมากด้วย:

  • tourniquet
  • tranexamic acid
  • local infiltration analgesia

Intraoperative transfusion rate:

ใกล้ 0% ในหลายศูนย์

2. Thromboembolism (VTE)

หนึ่งใน complication ที่น่ากลัวที่สุด

Incidence without prophylaxis

  • DVT: 40–88%
  • asymptomatic PE: 10–20%
  • symptomatic PE: 0.5–3%
  • mortality: up to 2%

With prophylaxis

Symptomatic VTE ลดลงมาก

Example:

  • aspirin ~3.45%
  • enoxaparin ~1.82%

Prevention

ต้อง balance:

  • thrombosis risk
    vs
  • bleeding risk

Main strategies:

  • pharmacologic prophylaxis
  • early mobilization

3. Peroneal Nerve Palsy

Most common severe neurologic complication

Clinical findings

  • numbness
  • paresthesia
  • foot drop

Risk factors

  • severe valgus deformity
  • flexion contracture
  • prolonged tourniquet >120 min
  • external compression
  • previous spine disease (“double-crush”)

Mechanisms

  • stretch injury
  • retractor injury
  • hematoma
  • swelling
  • compression while lying in bed

Initial management

  • loosen dressing
  • flex knee 30°
  • X-ray evaluate prosthesis

Prognosis

ส่วนใหญ่ recovery ภายใน:
12–18 months

4. Tourniquet-related Ischemic Injury

Risk เพิ่มเมื่อ:

  • cuff pressure สูง
  • ischemic time นาน

Principle:

lowest pressure + shortest time possible

5. Arterial Injury

Rare แต่ severe

Incidence

~0.013–0.17%

Most common vessel:

  • popliteal artery

Clinical presentations

  • acute hemorrhage
  • limb ischemia
  • chronic swelling/pain
  • pseudoaneurysm

Important point

Mortality + PJI risk สูงขึ้นมากเมื่อเกิด vascular injury

6. Wound Healing Problems

Risk factors:

  • DM
  • obesity
  • RA
  • poor circulation
  • prior incision

Persistent drainage

ต้อง:

  • exclude infection
  • aspiration/culture
  • irrigation & debridement if needed

May require:

  • plastic surgery consult

7. Surgical Site Infection / PJI

Incidence

~1%

Risk factors

  • diabetes
  • obesity
  • smoking
  • malnutrition
  • inflammatory arthritis

Classification

Acute:

  • within 3–6 weeks

Late:

  • often hematogenous

8. Intraoperative Fracture

Incidence

~0.39%

Stable fracture:
→ observation

Unstable:
→ fixation

Outcomes generally excellent

9. Ligament Injury

Most common:

  • MCL injury

Incidence:
~1.2%

Treatment

  • primary repair
  • hinged brace
  • increased prosthetic constraint

10. Myocardial Infarction

Highest risk:

  • 2–4 weeks postop
  • age ≥80

Important:
Complication after first staged TKA predicts recurrence risk in second procedure

INTERMEDIATE & LATE COMPLICATIONS

11. Aseptic Loosening

หนึ่งใน most common causes of failure

Risk factors

  • younger age (<50)
  • polyethylene wear
  • poor fixation
  • implant stress

Diagnosis

Serial X-ray:

  • progressive radiolucency >2 mm

Workup สำคัญ:

ต้อง exclude PJI

Labs:

  • WBC
  • CRP
  • aspiration if suspicious

Management

Symptomatic + infection excluded:
→ revision TKA

12. Joint Instability

Major cause of revision

Types

  • flexion instability
  • extension instability
  • combined

Risk factors

  • RA
  • connective tissue disease
  • osteoporosis
  • neuropathy
  • obesity
  • ligament imbalance

Clinical presentation

  • pain
  • recurrent effusion
  • giving way

Treatment

Usually:

  • revision to constrained implant

Sometimes:

  • bracing

13. Late/Chronic PJI

Usually hematogenous

ต้องสงสัยใน:

  • chronic pain
  • swelling
  • effusion
  • loosening

14. Patellofemoral Complications

Common reason for reoperation

Includes:

  • instability
  • loosening
  • fracture
  • extensor rupture
  • patella clunk
  • anterior knee pain

Patellofemoral Instability

Incidence

1–20%

Diagnosis

  • sunrise/Merchant view
  • CT for component rotation

Causes

  • malrotation
  • malalignment
  • soft tissue imbalance

Treatment

  • lateral release
  • realignment
  • revision component

Patellar Component Loosening

Associated with:

  • osteolysis
  • malposition
  • instability

Symptomatic:
→ revision

Patella Fracture

Incidence

~0.3%

Causes

  • component malposition
  • AVN
  • trauma
  • excessive flexion

Treatment depends on

  • displacement
  • component fixation
  • extensor mechanism integrity

Extensor Mechanism Rupture

Feared complication

Usually:

  • patellar tendon rupture

Clinical presentation

  • inability to extend knee
  • extensor lag

Diagnosis

  • X-ray
  • MARS MRI/CT

Treatment

  • surgical repair/reconstruction

Patella Clunk Syndrome

Classic finding:

clunk during extension from 60° → 30°

Cause:

  • fibrous nodule under quadriceps tendon

Anterior Knee Pain

Possible causes:

  • patellofemoral pathology
  • unresurfaced patella

15. Periprosthetic Fracture

Common in:

  • osteoporosis
  • RA
  • arthrofibrotic knees
  • revision TKA

Femoral fractures

Supracondylar most common

Risk:

  • anterior femoral notching

Treatment

Stable + well-fixed:
→ nonoperative

Displaced/loose:
→ ORIF or revision

Tibial fractures

Rare

Treatment based on:

  • displacement
  • implant stability

16. Polyethylene Wear

Causes:

  • activity
  • obesity
  • malalignment
  • implant design

Clinical

  • pain
  • swelling
  • progressive deformity

Diagnosis

X-ray:

  • joint space narrowing

Management

  • observe
  • liner exchange
  • revision if osteolysis/loosening

17. Osteolysis

Usually from polyethylene wear debris

If associated with loosening:
→ revision surgery

If stable:
→ serial X-rays

18. Arthrofibrosis

Postoperative stiffness from scar tissue

Functional flexion requirements

Activity

Flexion needed

Walking

67°

Stair ascent

83°

Stair descent

100°

Rise from chair

93–105°

Risk factors

Best predictor:

poor preop ROM

Other causes:

  • infection
  • malposition
  • poor rehab
  • pain

Treatment

  • manipulation under anesthesia
    (best within 3 months)
  • arthroscopic lysis
  • revision if malpositioned implant

19. Persistent Pain & Dissatisfaction

~20% patients:

  • dissatisfied
    or
  • persistent moderate/severe pain

Possible causes

  • unrealistic expectations
  • technical failure
  • referred pain
  • pain catastrophizing
  • instability
  • infection
  • metal hypersensitivity

20. Metal Hypersensitivity

Metals:

  • cobalt
  • chromium
  • nickel

Symptoms

  • persistent pain
  • effusion
  • rash

Diagnosis of exclusion:

exclude infection/loosening/instability first

Testing

Controversial:

  • patch testing
  • lymphocyte transformation testing

No role for routine screening currently

High-yield Clinical Pearls

  • DVT risk after TKA without prophylaxis extremely high
  • Foot drop after TKA = peroneal nerve palsy until proven otherwise
  • Severe valgus/flexion contracture → high peroneal nerve risk
  • Persistent wound drainage must be treated aggressively to prevent PJI
  • Most important step in aseptic loosening workup = exclude infection
  • Instability is a major cause of revision TKA
  • Patellofemoral complications are common causes of reoperation
  • Arthrofibrosis responds best to early manipulation (<3 months)
  • About 20% of patients remain dissatisfied despite technically successful TKA
  • Metal hypersensitivity is rare and remains a diagnosis of exclusion

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Hemarthrosis

Hemarthrosis

Definition

Hemarthrosis = bleeding into joint cavity

เป็นสาเหตุสำคัญของ:

  • acute monoarthritis
  • painful swollen joint

Definitive diagnosis:

arthrocentesis

Causes of Hemarthrosis

แบ่งเป็น:

  • traumatic
  • nontraumatic

1. Traumatic Hemarthrosis

สาเหตุพบบ่อยที่สุด

Clinical clue

  • swelling within hours after injury
  • severe pain
  • rapid effusion (<12 hr)

Rapid swelling → suspect:

  • ligament injury
  • osteochondral fracture
  • intraarticular fracture

Knee Hemarthrosis (high-yield)

Most common mechanism:

  • twisting injury on loaded knee

Common associated injuries

Injury

Approximate frequency

ACL tear

~70%

Meniscal tear

~10%

Patellar subluxation/dislocation

10–15%

Osteochondral fracture

2–5%

Physical examination

ตรวจ:

  • joint line tenderness
  • patella tenderness
  • ligament stability

Tests:

  • valgus/varus
  • anterior drawer/Lachman
  • posterior drawer

Imaging

Initial

  • plain radiograph

Knee views:

  • AP
  • lateral
  • patellar
  • tunnel

CT

ใช้เมื่อ:

  • fracture suspected but X-ray negative

MRI

ดีที่สุดสำหรับ:

  • ligament
  • meniscus
  • cartilage

Lipohemarthrosis

Definition

fat + blood in joint

Suggests:

intraarticular fracture

Diagnosis

  • arthrocentesis
  • CT/MRI
  • X-ray fluid-fluid level

Double fluid-fluid level → more specific

Hemarthrosis after Minimal Trauma

ให้คิดถึง:

  • hemophilia
  • coagulation disorder
  • acquired factor inhibitor

ถ้าไม่มี bleeding disorder:

  • ACL tear
  • meniscal tear ยังเป็นไปได้

Postoperative Hemarthrosis

พบได้หลัง:

  • TKA
  • arthroscopy

Cause พบบ่อย:

  • hypertrophic synovium impingement

Treatment:

  • synovectomy
  • embolization

2. Nontraumatic Hemarthrosis

Important causes:

  • bleeding disorders
  • anticoagulants
  • OA/chondrocalcinosis
  • neuropathic joint
  • septic arthritis
  • vascular lesions
  • tumors

Bleeding Disorders

Important labs

  • CBC
  • PT
  • aPTT

Hemarthrosis มักเกิดจาก:

coagulation factor defect มากกว่า platelet disorder

Hemophilia

Most common musculoskeletal manifestation:

hemarthrosis

Common joints

  • knee
  • elbow
  • ankle
  • hip
  • shoulder

Types of Hemophilic Hemarthrosis

Acute

  • painful
  • swollen
  • warm
  • ↓ ROM

Older patients may report:

  • “aura”
  • tingling/warmth before swelling

Subacute

  • synovial hypertrophy
  • fibrosis
  • reduced ROM

Pain may not be prominent

Chronic

→ hemophilic arthropathy

Features:

  • chronic pain
  • stiffness
  • deformity
  • OA-like symptoms

Pathophysiology of Hemophilic Arthropathy

Blood in joint causes:

  • synovial proliferation
  • cartilage toxicity
  • osteoclast activation
  • recurrent bleeding (“target joints”)

Important:

blood can damage cartilage within ~2 days

Hemophilic Arthropathy Radiographic Stages

Stage

Finding

1

soft tissue swelling

2

osteoporosis

3

osseous deformity

4

cartilage destruction

5

joint disorganization

MRI sensitive กว่า X-ray มาก

Osteoarthritis-related Hemarthrosis

Rare

Usually diagnosis of exclusion

Associated with:

  • degenerative meniscal tear
  • chondrocalcinosis

Septic Arthritis

Rarely causes hemarthrosis

Always exclude if:

  • fever
  • systemic symptoms
  • inflammatory synovial fluid

Vascular Causes

  • aneurysm
  • pseudoaneurysm
  • vitamin C deficiency

May require:

  • surgery
  • embolization

Tumor-associated Hemarthrosis

Important benign tumors:

Synovial hemangioma

  • recurrent painful monoarthritis
  • usually knee
  • MRI best diagnostic tool

TGCT/PVNS

(tenosynovial giant cell tumor / pigmented villonodular synovitis)

Features:

  • recurrent hemarthrosis
  • chronic swollen joint
  • locking/catching
  • dark brown aspirate

MRI:

  • hemosiderin → dark on T1/T2

Treatment:

  • synovectomy

Clinical Manifestations

Depends on acuity

Common findings:

  • pain
  • swelling
  • warmth
  • stiffness
  • ↓ ROM

Synovial Fluid Findings

Appearance

  • red
  • pink
  • brown/rusty

Important clues

True hemarthrosis

  • usually does NOT clot
  • xanthochromia after centrifuge

Traumatic tap

  • blood increases during aspiration
  • straw-colored supernatant
  • usually clots

Diagnosis

Gold standard

Arthrocentesis

Typical findings:

  • uniformly bloody fluid
  • xanthochromia

When aspiration may not be necessary

  • known hemophilia
  • known traumatic intraarticular injury
  • septic arthritis unlikely

Additional synovial studies

ถ้า diagnostic uncertainty:

  • cell count
  • differential
  • Gram stain
  • culture
  • crystal analysis
  • cytology (if malignancy suspected)

Differential Diagnosis

1. Traumatic tap

Key distinction:

  • fresh clotting blood
  • no xanthochromia

2. Septic arthritis

Suggestive features:

  • fever
  • inflammatory synovial fluid
  • positive culture

3. Crystal arthritis

  • gout
  • CPPD

Diagnosed by crystals

CPPD occasionally causes pseudo-hemarthrosis

4. Reactive arthritis

History:

  • antecedent infection

5. Lyme arthritis

  • endemic exposure
  • large knee effusion

Treatment

General Acute Management

Initial

  • immobilization
  • ice
  • compression

Aspiration

Indications:

  • tense effusion
  • pain relief
  • diagnostic uncertainty

Use large-bore needle (eg 18G)

Analgesia

Avoid:

  • nonselective NSAIDs first 48–72 hr

COX-2 selective safer initially

Postacute

NSAIDs may be used after bleeding risk decreases

Important concept

Single episode hemarthrosis:

usually does not require lavage

Trauma-associated Hemarthrosis

  • immobilize
  • orthopedic consultation
  • assess fracture/internal derangement

Hemophilia-associated Hemarthrosis

Requires:

  • factor replacement
  • aggressive treatment to prevent arthropathy

Children especially vulnerable

Anticoagulation-associated Hemarthrosis

Usually managed with:

  • immobilization
  • analgesia

Consider:

  • anticoagulation reversal if severe

Persistent/recurrent bleeding:

search for structural lesion

Postoperative Hemarthrosis

May require:

  • revision surgery
  • embolization

Tumor-associated Hemarthrosis

Treatment:

  • arthroscopic/surgical synovectomy

Prognosis

Depends on cause

Important:

recurrent hemarthrosis in hemophilia → chronic disabling arthropathy

High-yield Clinical Pearls

  • Acute knee hemarthrosis after twisting injury → ACL tear until proven otherwise
  • Rapid swelling within hours after trauma strongly suggests intraarticular injury
  • Lipohemarthrosis = think intraarticular fracture
  • Minimal trauma + hemarthrosis → evaluate coagulopathy
  • True hemarthrosis usually does not clot
  • Xanthochromia supports true hemarthrosis
  • Hemophilic “aura” (tingling/warmth) is classic
  • Recurrent monoarticular bloody effusion → think PVNS/TGCT or synovial hemangioma
  • Bloody joint fluid does NOT exclude septic arthritis
  • Repeated hemarthrosis destroys cartilage and leads to chronic arthropathy
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