Background. Periprostetic joint infections (PJI) are often difficult to diagnose, to treat and often leave the patient with severe impaired function. The presence of low virulent bacteria is frequently discovered in apparent aseptic revisions of shoulder arthroplasties and pose a challenge to diagnose preoperatively. Dual Isotope In111 Leucocyte/ Tc99 Bone Marrow SPECT CT scan (L/BMS) is considered the radionuclide gold standard in preoperative diagnosing PJI with reported high specificity and sensitivity in hip and knee arthroplasties. Unfortunately, it is labour-intensive and expensive to perform and documentation using L/BMS on shoulder arthroplasties lack. Aim. To investigate if L/BMS succeeds in detecting shoulder PJI compared to tissue cultures obtained perioperatively. Method. All patients referred to a highly-specialised shoulder department with a painful or stiff shoulder-arthroplasty were included in the cohort. To diagnose infection as a possible cause of arthroplasty failure a L/BMS was planned for all patients. If the arthroplasty was revised, 5 tissue biopsies were obtained from the most infection-suspicious site during revision. Biopsies were cultured in broth and on plates for 14 days due to the high frequency of low virulent infection in shoulder revisions. Infection was defined as growth of the same bacteria in 3 or more of 5 the biopsies. Results. During the observation period 71 patients were referred. Revision surgery was performed in 62% of the patients (44/71) of which 29 also had been examined by L/BMS. A microbiological diagnose was available for all. The most predominant organism isolated was P. Acnes. Two patients both had a positive L/BMS and positive cultures. Negative L/BMS and negative cultures were found in 20 patients. The remaining 7 patients had negative L/BMS, but positive cultures. The two patients with a positive L/BMS both showed overt clinical signs of infection. L/BMS show a sensitivity 0.22 95%CI(0–0.49) and specificity 1.00 95%CI(1.00–1.00) in detecting shoulder PJI. The Positive Predictive Value is 1.00 95%CI(1.00–1.00) and Negative Predictive Value 0.74 95%CI(0.57–0.90). No patients infected with P. Acnes resulted in a positive scintigraphy nor had they preoperative or perioperative signs of infection. Conclusion. Only patients with severe infectious symptoms of shoulder PJI resulted in positive L/BMS. Hence, the scan added nothing to the preoperative clinical diagnose. In111 Leucocyte/ Tc99 Bone Marrow SPECT CT scan cannot be recommended as a standard screening procedure when evaluating failed shoulder arthroplasties for possible infection

Aim. To demonstrate the use of indium-111 white-cell labelled SPECT CT (In111-WC-SPECT-CT) in bone infection. Method. This novel imaging modality is useful in bone infection. We present three cases of complex osteomyelitis to illustrate this. All were imaged with conventional modalities, but conclusive diagnosis could not be achieved. In111-WC-SPECT-CT was used to provide the definitive imaging that allowed successful treatment. Results. Case 1- A 29 y/o Male with spina bifida presented with chronic calcaneal osteomyelitis. Previous treatment included debridement, but recurrent infection ensued. MRI showed widespread changes consistent with infection throughout the calcaneus and a below knee amputation was planned. In111-WC-SPECT-CT (Figure 1) showed a distinct localised nidus of infection. A targeted sequestrectomy was performed and the patient has been infection free for four years. He was spared the amputation. Case-2- A 73 y/o male presented with a radiation induced colo-cutaneous fistula and pelvic chronic osteomyelitis. Surgical treatment included multiple debridements and sequestrectomy. He re-presented pain with pain in his pelvis six months later. MRI was performed and oedema seen in the bone. This was presumed to be infection and further surgery was planned. An In111-WC-SPECT-CT was then performed and confirmed no residual bone infection. The patient was spared surgery. Case-3- A 38 y/o female was involved in an RTA 6 months prior to presentation. She underwent fixation of her tibia with skin grafting for an open fracture. There was clinical suspicion of deep infection. The metalwork made MRI difficult to interpret. An In111-WCC-SPECT-CT confirmed infection around the metal screw and this evidence instigated a prolonged course of antibiotics to suppress the infection. The screw will be removed after the fracture heals. Conclusions. In-111-WC-SPECT-CT is an emerging imaging modality. We present three cases of complex bone and joint infection; where this imaging has altered the course of treatment

Introduction. The degree of cartilage degeneration assessed intraoperatively may not be sufficient as a criterion for patellar resurfacing in total knee arthroplasty (TKA). However, single-photon emission tomography/computed tomography (SPECT/CT) is useful for detecting osteoarthritic involvement deeper in the subchondral bone. The purpose of the study was to determine whether SPECT/CT reflected the cartilage lesion underneath the patella in patients with end-stage osteoarthritis (OA) and whether clinical outcomes after TKA without patellar resurfacing differed according to the severity of patellofemoral (PF) OA determined by visual assessment and SPECT/CT findings. Methods. This study included 206 knees which underwent TKA. The degree of cartilage degeneration was graded intraoperatively according to the International Cartilage Repair Society grading system. Subjects were classified into four groups according to the degree of bone tracer uptake (BTU) on SPECT/CT in the PF joint. The Feller's patella score and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed preoperatively and postoperative 1 and 2 years. Results. The increased BTU in the PF joint was associated with more severe degenerative cartilage changes underneath the patella (P < 0.001). The risk for the presence of denudated cartilage was greater in the high uptake group (odds ratio = 5.89). There was no association between clinical outcomes and visual grading of patellar cartilage degeneration or the degree of BTU on SPECT/CT. Discussion and Conclusions. The visual assessment of the degree of cartilage degeneration underneath the patella and preoperative SPECT/CT evaluation of the PF joint were not predictive of clinical outcome after TKA with unresurfaced patella