SPECT/CT is a promising diagnostic modality in patients with painful total knee arthroplasty (TKA). The purpose of this study is to introduce a novel standardized SPECT/CT algorithm and evaluate its clinical application and reliability. A novel SPECT/CT localization scheme consisting of 9 tibial, 9 femoral and 4 patellar regions on standardized axial, coronal and sagittal slices is proposed. It was piloted in 18 consecutive patients with post TKA pain. The tracer activity on SPECT/CT was recorded using a color-coded scale (0-10). The inter- and intra-observer reliability was assessed for localization and tracer activity. The prosthetic component position was assessed in the CT images after 3D reconstruction using standardized frames of reference. The median inter- and intra-observer differences and ranges of the measured angles were calculated along with the ICC values for inter- and intra-observer reliability. The localization scheme showed very high inter- and intra-observer reliabilities for all regions. The measurement of component position was highly reliable in all cases with sufficient visibility of anatomical landmarks. The median inter-observer difference between alignment measurements for tibial and femoral components was less than 3 degrees (range 0 degrees -6 degrees ). The median intra-observer variability for these was less than 2 degrees (range 0 degrees -5 degrees ). The SPECT/CT algorithm presented is both reliable and useful in the management of patients with painful TKA. It combines biomechanical and metabolic data (tracer localization) providing an extra dimension to the understanding of this difficult condition. The clinical value of SPECT/CT in patients with unexplained pain following TKA should be further investigated.

BackgroundThe purpose of our study was to evaluate the clinical value of hybrid SPECT/CT for the assessment of patients with painful total knee arthroplasty (TKA).MethodsTwenty-three painful knees in patients following primary TKA were assessed using Tc-99m-HDP-SPECT/CT. Rotational, sagittal and coronal position of the TKA was assessed on 3D-CT reconstructions. The level of the SPECT-tracer uptake (0-10) and its anatomical distribution was mapped using a validated localization scheme. Univariate analysis (Wilcoxon-Mann-Whitney, Spearmean`s-rho test, p < 0.05) was performed to identify any correlations between component position, tracer uptake and diagnosis.ResultsSPECT/CT imaging changed the suspected diagnosis and the proposed treatment in 19/23 (83%) knees. Progression of patellofemoral OA (n = 11), loosening of the tibial (n = 3) and loosening of the femoral component (n = 2) were identified as the leading causes of pain after TKA.Patients with externally rotated tibial trays showed higher tracer uptake in the medial patellar facet (p = 0.049) and in the femur (p = 0.051). Patients with knee pain due to patellofemoral OA showed significantly higher tracer uptake in the patella than others (p < 0.001).ConclusionsSPECT/CT was very helpful in establishing the diagnosis and guiding subsequent management in patients with painful knees after TKA, particularly in patients with patellofemoral problems and malpositioned or loose TKA.

We present the case of a 17-year-old ice-hockey player, who complained about persistent left medial knee pain having undergone a refixation of a grade III osteochondritis dissecans with biodegradable pins, a reconstruction of the anterior cruciate ligament (ACL) and a medial meniscal repair 1 year previously. Sequential MRIs performed 8 and 12 months after surgery were inconclusive, and failed to show the insufficient integration of the osteochondral fragment. Combined single photon emission and conventional computerized tomography (SPECT/CT) clearly revealed the cause of the patient's persistent knee problems-the osteochondral fragment had not integrated. SPECT/CT may hold great clinical value for symptomatic patients who have previously undergone treatment for osteochondral lesions, and it should be considered as alternative diagnostic imaging modality.

No abstract

No abstract