The clinical relevance of single-photon emission CT/CT after reverse shoulder arthroplasty

The aim of this study was to evaluate the clinical value of single-photon emission CT (SPECT)/CT in detecting postoperative complications following reverse shoulder arthroplasty (RSA). This was a retrospective study involving 87 patients who underwent SPECT/CT after RSA. Of these, 73 presented with pain affecting the RSA, and 14 served as a control group with an asymptomatic RSA on one side. SPECT/CT images were analyzed using standardized anatomoclinical zones, and the uptake of tracer was graded from 0 to 3. Grades 0 and 1 were considered as minor, whereas grades 2 and 3 were classified as major uptake. The SPECT/CT findings were correlated with previous clinical evaluation and classified as those in symptomatic or asymptomatic patients. Major tracer uptake was frequently seen in symptomatic patients around the acromion and spine of the scapula, with intense uptake in those with a fracture. In contrast, asymptomatic patients had minimal uptake around the scapula. There was major uptake in the glenoid in most patients, gradually declining over time in asymptomatic findings. Patterns of uptake in symptomatic patients were seen in association with infection, heterotopic ossification, scapular notching, and aseptic humeral loosening. The uptake was low in the humeral shaft in asymptomatic patients but increased after eight to 12 months in association with aseptic humeral loosening. Major uptake was also often seen in the acromioclavicular and sternoclavicular joints and the cervicothoracic spine in both symptomatic and asymptomatic patients. SPECT/CT effectively detects (stress) fractures, particularly involving the acromion and spine of the scapula. Its clinical value is more limited for differentiating infection, heterotopic ossification, scapular notching, and aseptic humeral loosening, especially during the first postoperative year. Aseptic loosening can be assessed more reliably by focusing on the humeral shaft. Differentiating the findings in symptomatic and asymptomatic patients in the acromioclavicular, sternoclavicular, and cervicothoracic regions remains difficult. Targeted infiltrations of local anaesthetic and steroid remain primarily diagnostic, with SPECT/CT providing anatomical localization when the source of the pain remains unclear.