Revision Knee Replacement

Painful knee arthroplasty

Painful knee arthroplasty presents a major diagnostic challenge. In certain cases even a careful history-taking, meticulous clinical examination and numerous investigations may not help in reaching a diagnosis. Infection is particularly difficult to diagnose. To date there is no single preoperative investigation that can reliably diagnose an infection. Our inability to diagnose subclinical infection before revision surgery is still a major concern.

Possible causes of painful knee arthroplasty

Infection
Aseptic loosening
Instability
Stiffness
Mal-rotation
Mal-alignment
Patellar pain or dislocation
Extensor mechanism rupture
Incompetent medial collateral ligament
Periprosthetic fracture
Implant breakage
Complex regional pain syndrome
Hip or spine pathology (referred pain)
Unexplained pain (1/300)

Management

History

Date of index operation, postoperative pain relief/problems, wound leak, wound infection (and need for antibiotics), pain at rest, mechanical pain, stair climbing and descent, any injuries, medical problems, especially diabetes and rheumatoid arthritis.

Examination

Limp, walking aid, leg alignment, patellar alignment/tracking/ tenderness, inflammation, effusion, quadriceps tone, CRPS (RSD) signs, joint tenderness localized/generalized, ROM active/passive, laxity in sagittal/coronal plane and finally assess the hip, spine and foot.

Investigations

Plain weight-bearing x-ray, bloods (including WCC, ESR and CRP – IL-6 (expensive) in specialist units), bone scan (not helpful until at least year after the index procedure), white cell-labelled bone scan, knee aspiration, fluoroscopic alignment check, CT scan to check rotation and long leg films to assess the overall alignment. SPECT bone scan and SPECT-CT has also been a novel imaging option to de