Does Arthrography Improve Accuracy of SPECT/CT for Diagnosis of Aseptic Loosening in Patients with Painful Knee Arthroplasty: A Systematic Review and Metaanalysis

SPECT/CT combines scintigraphy with a CT scan forming a 3-dimensional reconstruction of bone-tracer uptake patterns. It has become a fundamental component of the work-up of a painful total knee arthroplasty (TKA). The addition of an arthrogram is purported to improve its diagnostic yield. The aim of this study was to assess whether the addition of a concurrent arthrogram to a SPECT/CT enhances its sensitivity and specificity for diagnosing aseptic loosening in a painful total knee replacement. Methods: PubMed, Embase, and Scopus were searched in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Included studies compared the results of SPECT/CT with or without an arthrogram against an appropriate reference standard for diagnosing TKA aseptic loosening. The quality of included studies was independently assessed using the QUADAS-2 tool. Results: In total, 160 abstracts were identified by our search strategy. Of these, 6 studies comprising 472 patients met our inclusion criteria. All included studies used operative findings or a period of clinical and radiologic observation as reference standards. The SPECT/CT arthrogram was more sensitive in identifying aseptic loosening of knee prostheses, and it also provided greater specificity for excluding its diagnosis. Conclusion: The amalgamated results of included studies of the use of SPECT/CT demonstrate it is the best test in helping determine aseptic loosening in patients with painful TKAs (specificity, 97% vs. 85%). It is also a more sensitive test (sensitivity, 78% vs. 75%). Considering the potential morbidity of injection of contrast into the prosthetic joint, addition of an arthrogram to SPECT/CT is not beneficial and is potentially harmful.