BACKGROUND: Patients who have had prior injections, surgeries such as arthroscopies, and have existing osteosynthetic implants in the hip and knee have an increased risk of periprosthetic infections when undergoing hip (THA) or total knee arthroplasty (TKA).

OSTEOSYNTHESIS: For patients with osteosynthetic implants in the knee joint, a two-stage procedure (implant removal followed by TKA) is recommended based on the available literature and the high colonization rates. A two-stage procedure is also recommended for patients with hip implants. If there is an increased risk of re-fracture between implant removal and THA, a one-stage procedure can also be used.

ARTHROSCOPY: An arthroscopy before THA or TKA increases the risk of complications and reoperations, in particular with short intervals. The interval should be at least 6 months, ideally 9 months.

PREOPERATIVE INJECTIONS: Preoperative injections before THA clearly increase the risk, while for TKA, there is a non-significant trend. The earliest time for a prosthesis after injection should be 6 weeks, preferably 3 months. The waiting period should be balanced against the patients' discomfort and high levels of suffering, and patients should be informed about the risks.