summary Knee arthrodesis is the fusion of the tibiofemoral joint most commonly performed as a salvage for failed TKA or complete loss of extensor mechanism. The optimal position of the knee during fusion is 5° valgus, 0-10° of external rotation, and 0-15° of flexion. Absolute contraindications is presence of active infection. Indications Indications painful ankylosis after infection or trauma neuropathic arthropathy tumor resection salvage for failed TKA (most common) loss of extensor mechanism Contraindications Contraindications absolute active infection relative bilateral knee arthrodesis contralateral leg amputation significant bone loss ipsilateral hip or ankle DJD Technique Optimal Position 5-8° valgus 0-10° of external rotation (match other leg) 0-15° of flexion some limb shortening advantageous for patient self-care Techniques Intramedullary rod fixation technique can be one long antegrade device or a two part device connected at the knee patella can be left alone or incorporated into arthrodesis External fixation technique must allow compression of arthrodesis site done with unilateral external fixation, Ilizarov, or Taylor Spatial Frame Plate fixation technique can be done alone in combination with intramedullary nailing Complications Nonunion Infection Low back pain Ipsilateral hip degenerative changes Contralateral knee degenerative changes Fracture supracondylar femur or proximal tibial metaphysis fractures these occur from increased stress in these regions after arthrodesis