The use of patient-reported outcome measures (PROMs) to objectively and quantifiably assess patient symptomatology allows tracking of symptoms over time, measurement of the effect of healthcare interventions, and performance of cost-effectiveness analyses to assess and compare the value of treatment options. Many of the PROMs historically used had limited versatility because they were developed using classical test theory, which generates static tests that are not comparable with other measures assessing similar outcomes. Recently developed PROMs, however, were designed according to the principles of the newer item response theory (IRT), which allows for the creation of dynamic instruments deliverable in a variety of forms that are readily comparable with similar measures. IRT also enables computerized adaptive testing to decrease the burden of using PROMs by allowing rapid and complete data acquisition. IRT-based instruments are suitable for patient care and research and have been validated in a variety of populations, many of which are relevant to orthopaedic populations.