Msk Dermatology · Year 2 · from Msk Dermatology

Case 1: Primary Knee Osteoarthritis with Varus Deformity

Patient Presentation

Demographics: 67-year-old woman

Chief Complaint: "My right knee has been getting worse over the past two years, and now I can barely walk to the mailbox."

History of Present Illness: The patient describes gradually progressive right knee pain that began insidiously approximately five years ago. The pain is located primarily over the medial aspect of the knee and is worse with weight-bearing activities, particularly walking, climbing stairs, and rising from a seated position. She notes morning stiffness lasting approximately 15-20 minutes that improves with movement. The pain is relieved with rest but has become more constant over the past six months, occasionally awakening her at night. She has tried over-the-counter acetaminophen and ibuprofen with modest relief. She denies any history of significant knee trauma.

Past Medical History:

• Hypertension
• Type 2 diabetes mellitus
• Obesity (BMI 34 kg/m2)
• No prior joint surgeries

Medications:

• Lisinopril 20 mg daily
• Metformin 1000 mg twice daily
• Acetaminophen 650 mg as needed

Social History:

• Retired schoolteacher
• Never smoker
• No alcohol use

Family History:

• Mother had knee replacement at age 72

Physical Examination

• Vital Signs: BP 138/82 mmHg, HR 78 bpm, BMI 34 kg/m2
• Gait: Antalgic gait favoring the right leg, visible varus (bow-legged) deformity
• Right Knee:
• Bony enlargement of the joint margins
• Palpable crepitus with range of motion
• Tenderness along the medial joint line
• Small cool effusion present
• Range of motion: 5-110 degrees (reduced from normal 0-135 degrees)
• No warmth or erythema
• Varus alignment of approximately 10 degrees
• Stable ligamentous examination
• Left Knee: Mild crepitus, no effusion, full range of motion

Workup and Results

Laboratory Studies:

Imaging:

• Weight-bearing AP and lateral knee radiographs:
• Kellgren-Lawrence Grade 4 changes in the medial compartment
• Marked medial joint space narrowing with bone-on-bone contact
• Large marginal osteophytes
• Subchondral sclerosis and cyst formation
• Varus angulation of 10 degrees
• Lateral compartment relatively preserved

Clinical Image

Standing anteroposterior radiograph of the knee demonstrating advanced osteoarthritis with marked joint space narrowing, osteophyte formation, and subchondral changes. Source: Wikimedia Commons, CC BY-SA 3.0.

Diagnosis

Primary Osteoarthritis of the Right Knee, Kellgren-Lawrence Grade 4

Diagnostic Criteria Met:

• Age over 50 years
• Activity-related joint pain with relief at rest
• Morning stiffness less than 30 minutes
• Bony enlargement and crepitus on examination
• Characteristic radiographic findings (joint space narrowing, osteophytes, sclerosis)
• Normal inflammatory markers excluding inflammatory arthropathy

Treatment Plan

Non-Pharmacologic Management:

1. Weight loss: Referral to nutritionist with goal of 10% body weight reduction
2. Physical therapy: Quadriceps strengthening, range of motion exercises, gait training
3. Assistive device: Cane to be used in the left hand
4. Activity modification: Low-impact exercise (swimming, cycling)
5. Knee sleeve: For proprioceptive support

Pharmacologic Management:

1. Topical diclofenac gel: Applied to knee four times daily
2. Scheduled acetaminophen: 650 mg three times daily
3. Intra-articular corticosteroid injection: Triamcinolone 40 mg for acute symptom relief

Surgical Consultation: Given the severe radiographic changes, varus malalignment, and functional limitation despite conservative measures, the patient was referred for orthopedic evaluation for total knee arthroplasty.

Follow-up:

• Reassess response to conservative measures in 6-8 weeks
• Optimize diabetes and weight prior to potential surgery
• Continue physical therapy

Teaching Points

1. Weight-bearing radiographs: Essential for accurate assessment of joint space narrowing in knee osteoarthritis; non-weight-bearing films underestimate cartilage loss
2. Varus deformity: Results from preferential medial compartment cartilage loss, altering knee biomechanics and accelerating progression
3. Surgical indications: Failure of conservative management, significant functional limitation, and radiographic evidence of advanced disease support total knee arthroplasty consideration
4. Obesity and OA: Weight loss reduces mechanical joint loading (4 pounds of force reduction per pound lost) and systemic inflammation

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