BACKGROUND Endoprosthetic replacement (EPR) for limb salvage is an established treatment modality for orthopaedic malignancies around the knee. Increasingly, they are being used for non-tumour indications such as fractures, bone loss associated with aseptic loosening, septic loosening and ligament insufficiencies. METHODS We reviewed the evolution and biomechanics of knee EPRs. MEDLINE was searched using the PubMed interface to identify relevant studies pertaining to the use of knee EPRs in non-tumour conditions. Failures, mortality and knee scores were the main outcome measures. Subgroup analysis in the non-tumour conditions was also performed. RESULTS There were nine studies with an average follow-up of 3.3years (Range 1-5years) describing 241 EPRs used in non-tumour conditions. Re-operation for any reason occurred in 17% (41/241) of cases. The most common complication was infection (15%) followed by aseptic loosening (5%) and periprosthetic fractures (5%). The mortality rate averaged 22%. Infected knee arthroplasties were less likely to have a successful outcome when salvaged with an EPR with failure rates up to 33%. CONCLUSIONS Endoprosthetic replacement is a limb salvage option when other surgical options are unfeasible, especially in low demand elderly patients with limited life expectancy. They have low rates of failure in the medium term. LEVEL OF EVIDENCE Level 1.