82 Part I Chapter 3 Table4 Non-exhaustive Summary of Indications for SPECT/CT in the Postoperative Painful Knee Indication SPECT/CT Tracer, Description of Added Value Joint-preserving knee surgery Persistent pain (eg, OA after UKA) BS SPECT/CT, in a native knee OA can be detected on planar scintigraphy without SPECT/CT. Osteochondral defects BS SPECT/CT increased specificity compared with planar scintigraphy. Persistent or recurrent pain After ACL reconstruction Three-phase BS, including SPECT/CT. Beware of physiological uptake of biodegradable interference screws and assess tunnel position and widening or cyst formation and nonfusion of the screw or graft insufficiency [54]. Persistent or recurrent pain after corrective osteotomy BS SPECT/CT detects the most common complications: malalignment, intraoperative fracture, vascular injury, postoperative recurrence of deformity and patella baja15. Pay extra attention to uptake in the knee joint as a result of changed biomechanics after corrective osteotomy. Knee arthroplasty Aseptical complications post TKA See Tables 1 and 3 for pivotal SPECT/CT findings correlated with clinical relevance. Suspected synovitis post TKA Three-phase BS, including SPECT/CT, to differentiate from other pathologies. Suspected infection post TKA Start with three-phase BS, including SPECT/CT, precise localization of biological and biomechanical information leading to clinically relevant diagnosis, followed by dualtime WBC and bone marrow imaging: 3 and 24 hours p.i. or antigranulocyte antibody and bone marrow 3 and 6-8 hours p.i. Pain after UKA Very limited evidence of SPECT/CT after UKA [56]. Specific uptake patterns may indicate loosening, but more evidence is needed in these patients. Increased BTO in native joints points to extent of osteoarthritis. Integrating SPECT/CT in the management of post-operative knee pain Establishing the correct causes for postoperative knee pain ismandatory for guidance of optimal treatment. Often it is difficult to achieve a comprehensive understanding of the reasons for persistent, recurrent or newly onset postoperative knee pain. In addition to patient history and a detailed clinical examination, radiological imaging and RNI complement diagnostics in this challenging group of patients. Conventional weight bearing radiographs (anterior-posterior, lateral, patellar skyline view) as well as long leg radiographs still are and will remain the first-line imaging in the painful knee joint. Radiographs are widely available, fast, inexpensive and offer the benefit of being a weight-bearing imaging technique, which is crucial for the knee. Clearly, radiographs give a sufficient first impression allowing assessment of knee joint degeneration, fractures, tumors and evidence of previous knee