Family Medicine · Year 3 · from Family Medicine

Case 3: Joint Injection - Knee Osteoarthritis

Patient Demographics

  • Age: 64 years old
  • Sex: Female
  • Occupation: Retired teacher

Chief Complaint

"My knee arthritis is flaring up again. The pills aren't helping enough."

History of Present Illness

Mrs. Patricia O'Brien is a 64-year-old woman with known bilateral knee osteoarthritis presenting with worsening right knee pain over the past 3 weeks. She describes the pain as a dull ache that worsens with activity, particularly climbing stairs and prolonged walking. She has morning stiffness lasting about 15-20 minutes. She has been taking naproxen 500 mg twice daily with modest relief. Physical therapy helped in the past but she has not been able to attend recently. She had a corticosteroid injection in this knee about 10 months ago with good relief lasting approximately 4-5 months.

Past Medical History

  • Bilateral knee osteoarthritis, right worse than left
  • Hypertension
  • Type 2 diabetes mellitus (well-controlled, A1c 6.9%)
  • No allergies

Current Medications

  • Metformin 1000 mg twice daily
  • Lisinopril 20 mg daily
  • Naproxen 500 mg twice daily PRN

Physical Examination

Right Knee:

  • Inspection: Mild bony enlargement, no erythema, no significant effusion
  • Palpation: Tenderness along medial joint line
  • Range of motion: 5-115 degrees (mild limitation in full flexion)
  • Crepitus present with range of motion
  • Ligamentous stability: Intact
  • No warmth compared to contralateral knee
  • No Baker's cyst

Left Knee: Mild crepitus, less symptomatic

Prior Imaging

X-rays from 1 year ago: Bilateral medial compartment joint space narrowing, osteophytes, right > left, Kellgren-Lawrence Grade 3

Clinical Image

Image: Anatomical illustration showing the superolateral approach for knee joint injection, with needle placement 1 cm superior and 1 cm lateral to the superolateral pole of the patella.

Image Source: Wikimedia Commons Attribution: Medical illustration, Educational Use URL: https://commons.wikimedia.org/wiki/File:Knee_injection_anatomy.png

Assessment

  1. Osteoarthritis, right knee - symptomatic flare, appropriate for intra-articular injection
  2. Type 2 diabetes - counsel about transient glucose elevation

Indication for Injection

  • Moderate-severe symptomatic OA
  • Inadequate relief with oral medications
  • Prior good response to injection
  • >3 months since last injection

Procedure: Intra-articular Knee Injection

Informed Consent:

  • Risks: Infection (rare, <1:10,000), bleeding, post-injection flare (transient pain increase in 12-36 hours), skin depigmentation at injection site, tendon weakening with repeated injections, temporary blood glucose elevation
  • Benefits: Pain relief lasting weeks to months, improved function
  • Alternatives: Continued oral medications, physical therapy, hyaluronic acid injection, surgical referral
  • Patient consented

Preparation:

  • Patient positioned supine with knee extended (or slight flexion with rolled towel)
  • Superolateral approach selected
  • Landmarks identified: Superior pole of patella, lateral edge of patella
  • Skin marked at injection site: 1 cm superior and 1 cm lateral to superolateral pole of patella
  • Skin cleansed with chlorhexidine, allowed to dry

Injection:

  • 22-gauge, 1.5-inch needle attached to syringe containing:
  • Triamcinolone acetonide 40 mg (1 mL)
  • 1% lidocaine 4 mL (for volume and immediate relief)
  • Needle inserted at 45-degree angle directed toward intercondylar notch
  • Advanced until "give" felt entering joint space
  • Aspirated - no blood or fluid obtained (small effusion would be aspirated and sent for analysis if present)
  • Injected slowly with minimal resistance
  • Needle withdrawn, pressure applied

Post-Procedure:

  • Adhesive bandage applied
  • Patient remained seated for 5 minutes
  • Ambulated without difficulty

Post-Injection Instructions

Activity:

  • Rest the knee for 24-48 hours - avoid strenuous activity
  • May resume normal activities gradually after 48 hours
  • No prolonged standing or walking today

Expected Course:

  • May experience soreness at injection site for 1-2 days
  • Lidocaine provides immediate but temporary relief (wears off in hours)
  • Steroid effect begins in 2-5 days, peaks at 1-2 weeks
  • Duration of relief varies: weeks to months

Diabetic Glucose Monitoring:

  • Blood glucose may be elevated for 3-5 days after injection
  • Monitor glucose more frequently
  • Contact office if glucose consistently >300 or symptoms of hyperglycemia

Warning Signs - Return If:

  • Increasing pain, swelling, or redness after 48 hours
  • Fever
  • Unable to bear weight
  • Warmth or redness of the knee

Follow-Up:

  • Return in 4-6 weeks to assess response
  • Consider physical therapy referral for strengthening and range of motion
  • Limit frequency of injections to 3-4 per year per joint

Teaching Points

  1. Corticosteroid injection indications:
  • Symptomatic OA inadequately controlled with conservative measures
  • Joint inflammation (inflammatory arthritis, crystal disease)
  • Soft tissue inflammation (bursitis, tendinopathy)
  1. Technique pearls:
  • Superolateral approach to knee is most commonly used
  • Enter 1 cm above and 1 cm lateral to superolateral patella
  • Aspiration before injection confirms intra-articular placement
  • If effusion present, aspirate before injecting steroid
  1. Frequency limits: 3-4 injections per year per joint maximum to avoid cartilage damage and soft tissue atrophy
  1. Post-injection flare: Occurs in ~10% of patients, typically 12-36 hours after injection, managed with ice and NSAIDs
  1. Contraindications:
  • Suspected septic joint (absolute)
  • Overlying skin infection (absolute)
  • Uncontrolled coagulopathy (relative)
  • Recent joint replacement (relative - risk of infection)
  1. Diabetic patients: Warn about transient glucose elevation lasting 3-7 days

Key Teaching Points Summary

Procedure Selection and Planning

  • Clear indication required for every procedure
  • Informed consent must include risks, benefits, alternatives
  • Assess clinician competency - know when to refer

Skin Procedures

  • ABCDE criteria for melanoma evaluation
  • Excisional biopsy preferred for suspected melanoma
  • Elliptical excision: orient along relaxed skin tension lines, 3:1 ratio
  • Proper specimen handling: orient, label, formalin, complete requisition

Wound Care

  • Systematic assessment: mechanism, depth, neurovascular status, tendon function
  • High-pressure irrigation is the most important infection-prevention step
  • Suture size and removal timing vary by location
  • Tetanus prophylaxis assessment at every wound visit

Joint Injections

  • Limit to 3-4 per year per joint
  • Sterile technique essential
  • Know the anatomy and landmarks
  • Warn diabetic patients about glucose elevation
  • Post-injection flare is common and self-limited

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