Evaluation of a Painful Total Knee Arthroplasty

Sarat Kunapuli, DO

EASTERN OKLAHOMA ORTHOPEDIC CENTER

Introduction

• Over a 150,000 total knee arthroplasties performed annually. 1

• Pain after TKA – common observation in about 20% of patients post-op 1

• Revision surgery required for some of the painful TKAs

• Revision TKAs on the rise

• Clear understanding of failure mechanism required prior to considering revision surgery

Introduction• A good history – invaluable

• Must have a diagnostic algorithm to identify cause of failure

• If performing revision – verify cause of failure

Algorithm

Common and Uncommons

Common causes - Prosthetic loosening, Infection, Instability, Component failure, Patellofemoral disorders, Periprosthetic osteolysis

Uncommon causes - particulate-induced synovitis, patellar clunk syndrome, lateral patellar facet syndrome, soft-tissue impingement syndromes, fabellar impingement, popliteus tendon dysfunction, tibial component overhang, HO, cutaneous neuroma

Non articular causes - Hip disease (arthritis, avascular necrosis, fracture, etc), spine disorders, vascular disease (insufficiency, aneurysm, thrombosis), reflex sympathetic dystrophy, psychological illness

History

Symptoms prior to surgery Symptoms after surgery Onset Was it getting better and then it got

worse? Type of pain Inquire previous x-rays, operative notes,

lab work – avoids duplication

History

Physical Exam Analyze gait pattern – watch for coronal plane thrust –

indicative of malalignment or ligamentous instability

Careful exam of skin –erythema or warmth

Examine for point tenderness – may represent tendonitis, bursitis

Thorough neurovascular exam

Examine spine and hip to rule out causes of referred pain

ROM testing

Stability – check collaterals at full extension, 30 degrees of flexion, and 90 degrees of flexion

Check stability in sagittal plane

Psychological assessment if warranted

Lab Evaluation Mainly done to distinguish between septic and aseptic

etiologies

ESR and CRP preliminary

ESR usually elevated for 3-6 months after uncomplicated TJA

CRP – normalizes 3-6 weeks after TJA

If CRP and/or ESR elevated – aspirate

Cell count and differential and cultures ( WBC >1100 and PMN > 64% and CRP > 1 Ghanem et al. JBJS 2008)

If inconclusive – aspirate again

Investigate metal allergy if pertinent

Imaging

Standard weight bearing x-rays – AP, lateral and Merchant

Full length standing films to assess malalignment Bone scan – not used commonly but can help to

identify loose components CT scan – can be used to assess bone stock and

to assess femoral and tibial component rotation Flouroscopy – used to assess dynamic stability

Imaging

Imaging

Imaging

Imaging - osteolysis

Imaging - Flouroscopy

Imaging – CT scan

Treatment Do not do anything until you find an underlying cause

Once you do find a cause – verify intraoperativly

Revision surgery without underlying cause – high failure rate

Questions?