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 - 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?