We report two cases in which arthrodesed knees were revised to total arthroplasties after the use of soft-tissue expanders. Case 1 had had multiple operations on her knee and had been arthrodesed for septic arthritis two years earlier. Case 2 had had knee arthrodesis for severe osteoarthritis 18 years before revision. In both patients, tissue expanders were used to increase the soft tissues available for cover and to help to mobilise the extensor mechanism. The operations were made much easier, and in both patients a range of motion from 0 degrees to 90 degrees was achieved at operation.