Abstract
Arthrodesis
Today, knee arthrodesis is most commonly performed for cases of chronic sepsis after total knee arthroplasty in patients who are not candidates for reimplantation. This is typically a host in whom the risk of recurrent infection is high, especially when extensor mechanism problems such as patellar tendon rupture is present. Local and systemic host factors place the patient at this high risk for failure of reimplantation. Local factors include chronic lymphedema, major vessel disease, venous stasis, extensive scarring and radiation fibrosis. Systemic problems include malnutrition, malignancy, extremes of age, hepatic or renal failure, diabetes mellitus and alcohol abuse. Also, at least in one study, patients who fail one two-stage reimplantation have at least a 50% change for recurrence the second time.
Methods of knee arthrodesis include external fixation, single or double plate fixation and intramedullary nailing either monolithic or modular. External fixation can be performed as a single procedure. With external ring fixators leg lengthening has been described. Plate and nailing procedures are commonly performed after the infection is eradicated. If infection recurs but fusion has occurred, removal of a modular nail may be difficult although techniques have been described. Fusion rates of 85% to 100% have been reported with the newer techniques and fusion rates are usually correlated with the amount of bone loss after removal of the prosthesis. Optimal position of fusion is slight anatomic valgus and slight flexion. Placing a bowed intramedullary nail with the bow anteromedially can facilitate this alignment. One study comparing arthrodesis after failed knee arthroplasty with primary total knee replacement found nearly identical Short-Form 36 scores. Physical mobility was better with knee arthroplasty but pain control was better with arthrodesis.
Resection Arthroplasty
Indication: Low demand patient with comorbidities
Results: Falahee et al.; 28 knees;15 patients walked independently; Most severely disabled more satisfied. Less disabled least satisfied.
Amputation - Above the Knee Amputations after TKA (Sierra et al)
Prevalence: 0.36% (all causes – most common was peripheral vascular disease), 0.14% (for causes related to TKA: infection, periprosthetic fracture, pain, bone loss, vascular complication)
Results: 25 amputations for causes related to TKA; Avg 8.6 years after TKA
Complications: deep infection 5, superficial infection 1, skin necrosis 1, perioperative death 1. 9 of 25 fitted with above knee prosthesis; Only 5 were walking even to limited degree with prosthesis
