79 SPECT/CT in the post-operative painful knee Table 3 Selection of Pivotal Structured SPECT/CT Findings After TKA in Defined Regions Correlated with Clinical Relevance, According to Hirschmann, et al [34]. SPECT/CT Finding Correlation to Clinical Relevance Increased BTO* in all femoral regions (anterior, posterior, medial and lateral) Indicative of loosening of femoral TKA component Increased BTO* only at the lateral femoral regions Indicative of loosening of femoral TKA component Increased BTO* in all tibial regions, including around the tibial stem Indicative of loosening of tibial TKA component Increased BTO* in the medial-tibial regions Indicative of varus position of the tibial component Increased patellar BTO,* most often at the lateral or craniolateral facet, less medial Indicative of patellar overloading, which may be treated with secondary patellar resurfacing Radiolucent lines >2 mm on CT part Indicative of loosening of TKA component *Bone turnover (BTO) on SPECT/CT. Figure 5 Standardized localization scheme of BTO on SPECT/CT after TKA. sa, superior anterior; sp, superior posterior; ia, inferior anterior; ip, inferior posterior; a, anterior; p, posterior; F, femur; T, tibia; P, patella. (Reprinted with permission from Hirschmann, et al. [48]). 3