Osteoarthritis Knee

Osteoarthritis of The Knee

1. Overview
• Epidemiology
• Definition
• Risk Factors
2. Clinical Approach to Knee Pain
3. Differential Diagnosis
4. Diagnosis of Knee OA
5. Management
• Lifestyle
• Medical
• Surgical

Overview: Epidemiology

• Knee OA most common cause of disability in adults
• Decreased work productivity, frequent sick days
• Highest medical expenses of all arthritis conditions
• Symptomatic Knee OA
• More than 10 million Americans ¹
• More than 11% of persons > 64yo ²

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Overview: Definition

Arthritis vs. Arthrosis

Gradual loss of articular cartilage in the knee joint

• 3 articulations:
1. Lateral condyles of the femur and tibia
2. Medial condyles of the femur and tibia
3. Patellofemoral joint

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Damage caused by a complex interplay of joint integrity, biochemical processes, genetics, and mechanical forces

Anatomy of The Knee

Anatomy of The Knee

Overview: Risk Factors

• Age ³
• Female
• Obesity
• Previous knee injury
• Lower extremity malalignment
• Repetitive knee bending
• High impact activities
• Muscle weakness ⁴

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Osteoarthritis of The Knee

1. Overview
• Epidemiology
• Definition
• Risk Factors
2. Clinical Approach to Knee Pain
3. Differential Diagnosis
4. Making The Diagnosis
5. Management
• Lifestyle
• Medical
• Surgical

Clinical Approach to Knee Pain

“Hey Doc, my knee’s been hurting!”

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History

• SOCRATES pain questions
• Inflammatory sx e.g. fever, hot joint
• History of trauma or surgery
• Instability
• Functional loss
• Prior treatment

Clinical Approach to Knee Pain

Physical Exam

• Vitals, BMI
• Palpation: isolate tenderness, effusion, crepitus
• ROM: measure degree of flexion
• Stability: ligaments, menisci
• Alignment: genu varus or valgus
• Function: gait, duck waddle

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Clinical Approach to Knee Pain

Varus Test (LCL)

Valgus Test (MCL)

McMurray Maneuver

(menisci)

Lachman Test (ACL)

Duck Waddle

(stability)

Clinical Approach to Knee Pain

Tests

• CBC, ESR, RF
• Arthrocentesis
• X-rays (3 views)
• Weight-bearing AP
• Lateral
• Tangential Patellar (Sunrise)
• MRI

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Osteoarthritis of The Knee

1. Overview
• Epidemiology
• Definition
• Risk Factors
2. Clinical Approach to Knee Pain
3. Differential Diagnosis
4. Diagnosis of Knee OA
5. Management
• Lifestyle
• Medical
• Surgical

Differential Diagnosis of Knee Pain

Medial Pain

• OA
• MCL
• Meniscus
• Bursitis

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Diffuse Pain

• OA
• Infectious arthritis
• Gout, pseudogout
• RA

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Lateral Pain

• OA
• LCL
• Meniscus
• Iliotibial band syndrome

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Anterior Pain

• OA
• Patellofemoral syndrome
• Prepateller bursitis
• Quadriceps mechanism

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Osteoarthritis of The Knee

1. Overview
• Epidemiology
• Definition
• Risk Factors
2. Clinical Approach to Knee Pain
3. Differential Diagnosis
4. Diagnosis of Knee OA
5. Management
• Lifestyle
• Medical
• Surgical

Diagnosis of Knee OA

Classic Clinical Criteria

• established by ACR, 1981
• sensitivity 95%, specificity 69%

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• knee pain plus at least 3 of 6 characteristics:
• > 50 yo
• Morning stiffness < 30 min
• Crepitus
• Bony tenderness
• Bony enlargement
• No palpable warmth ⁵

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Diagnosis of Knee OA

Classification Tree

• Clinical symptoms
• Synovial fluid
• WBC<2000/mm³
• Clear color
• High Viscosity
• X-rays
• Osteophytes
• Loss of joint space
• Subchondral sclerosis
• Subchondral cysts

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• Confirmed by arthroscopy

(gold standard) ⁶

No OA

Sensitivity 94 %;

Specificity 88 %

Diagnosis of Knee OA

Osteoarthritis of The Knee

1. Overview
• Epidemiology
• Definition
• Risk Factors
2. Clinical Approach to Knee Pain
3. Differential Diagnosis
4. Diagnosis of Knee OA
5. Management
• Lifestyle
• Medical
• Surgical

Management: Lifestyle

• Weight loss
• Nutrition referral
• Exercise Program
• PT referral
• Quadriceps strengthening
• ROM exercises
• Low impact activities e.g. swimming, biking ⁷
• Ambulatory assist devices
• Cane
• Walker
• Insoles
• Unloader knee braces

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Management: Lifestyle

Varus (bowlegged) vs Valgus (knock-kneed)

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G2 Unloader Brace

Management: Medical

• Glucosamine/Chondroitin
• Acetaminophen
• NSAIDs
• Cox-2 inhibitors
• Opioids
• Intraarticular injections
• Glucocorticoids
• Hyaluronans

Management: Medical

• Glucosamine/Chondroitin
• 1500 mg/1200 mg daily ($40-50/month)
• Glucosamine: building block for glycosaminoglycans
• Chondroitin: glycosaminoglycan in articular cartilage
• GAIT study, NEJM, Feb 23, 2006
• Multicenter, double blind, placebo-controlled, 24 wks, N=1583
• Symptomatic mild or moderate-severe knee OA
• Infrequent mild side effects e.g. bloating
• For mild OA, not better than placebo
• For moderate-severe OA, combination showed benefit ⁸
• Patient satisfaction

Management: Medical

• Acetaminophen
• Indication: mild-moderate pain
• 1000 mg Q6h PRN
• Better than placebo but less efficacious than NSAIDs ⁹
• Caution in advanced hepatic disease

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• NSAIDs
• Indication: moderate-severe pain, failed acetaminophen
• GI/renal/hepatic toxicity, fluid retention
• If risk of GIB, use anti-ulcer agents concurrently
• Agents have highly variable efficacy and toxicity

Management: Medical

• NSAIDs

¹⁰

Management: Medical

• Cox-2 inhibitors
• Indication: mod-severe pain, failed NSAID, risk of GIB
• OA pain relief similar to NSAIDs
• Fewer GI events e.g. symptomatic ulcers, GIB
• Celecoxib 200 mg daily
• GI/renal toxicity, fluid retention
• Increased risk of CV events?
• APC Trial: 700 pts each assigned to placebo, 200 BID, 400 BID
• Increased risk at higher doses ¹¹
• CLASS Trial: 8,000 pts compared Celecoxib vs Ibuprofen
• Similar risk to Ibuprofen ¹²

Management: Medical

• Opioid Analgesics
• Indication:
• Moderate-severe pain
• Acute exacerbations
• NSAIDs/Cox-2 inhibitors failed or contraindicated
• Oxycodone synergistic w/ NSAIDs ¹³
• Tramadol/acetaminophen vs codeine/acetaminophen
• Similar pain relief ¹⁴
• Avoid long-term use
• Caution in elderly
• Confusion, sedation, constipation

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Management: Medical

Intraarticular Injections

• Glucocorticoids
• Indication: pain persists despite oral analgesics
• 40 mg/mL triamcinolone (kenalog-40)
• Solution: 5 mL (lidocaine 4 mL + kenalog 1 mL)
• Limit to Q3months, up to 2 yrs
• Effective for short-term pain relief < 12 wks
• Acute flare w/in 48 hrs post-injection ¹⁵

Management: Medical

Intraarticular Injections

• Hyaluronans (e.g. Synvisc)
• Indication: pain persists despite other agents
• Synthetic joint fluid
• Pain relief similar to steroid injections
• 2 mL injection Qwk x 3, $560-760/series
• Medicare reimburses 80%, Medi-cal $455.90
• 60-70% patients respond, relief up to 6 months
• Patient satisfaction ^{16, 17}

Management: Medical

Intraarticular Injections

• Technique
• 22 gauge 1.5 inch needle
• Approach accuracy:
• Lateral mid-patellar 93% ¹⁸
• Patient supine
• Leg straight
• Manipulate patella
• Angle needle slightly posteriorly
• Inject after drop in resistance or fluid aspirated

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Management: Algorithm

Lifestyle Modifications

Acetaminophen PRN

NSAIDs PRN

Opioids PRN

Celecoxib

Steroid Injections

Hyaluronan Injections

Surgical Referral

Management: Surgical

When to Refer

• Knee pain or functional status

has failed to improve with

non-operative management

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Types of Procedures

• Arthroscopic Irrigation
• Arthroscopic Debridement
• High Tibial Osteotomy
• Partial Knee Arthroplasty
• Total Knee Arthroplasty

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Management: Surgical

High Tibial Osteotomy

• Indication:
• Unicompartmental arthritis
• Genu varus or valgus
• Realign mechanical axis
• Age < 60yo
• < 15 degrees deformity¹⁹

Management: Surgical

Partial Knee Arthroplasty

• Indication:
• Unicompartmental arthritis
• Ligaments spared
• Increased ROM
• Faster recovery
• Prosthesis 10-yr survival: 84% ²⁰

Management: Surgical

Total Knee Arthroplasty

• Indication:
• Diffuse arthritis
• Severe pain
• Functional impairment
• Pain relief > functional gain
• ACL sacrificed
• PCL also may be sacrificed
• Prosthesis 10-yr survival: 90% ²¹