Imaging evaluation of periprosthetic loosening: A primer for the general radiologist

In response to an ageing global population, the primary hip and knee arthroplasty rate continues to increase. Although an effective treatment, up to 25% patients may require revision arthroplasty during their lifetime, commonly due to periprosthetic loosening. Revision procedures are associated with significantly increased healthcare costs; therefore, timely and accurate diagnostics are critical for clinicians and patients. Loosening, which may be septic or aseptic, remains a challenge and requires thorough clinical examination and multimodal imaging evaluation. Plain radiographs remain an essential diagnostic tool but advanced imaging modalities such as computed tomography, magnetic resonance imaging and nuclear medicine are playing an increasingly important role. This comprehensive review, through outlining the available radiological modalities, their respective strengths and weaknesses and the pertinent imaging findings, may help radiologists and orthopaedic surgeons make more informed decisions in the management of periprosthetic loosening.