Assessment of Orthopedic Surgical Implants in Dogs Using 18F-Sodium Fluoride Positron Emission Tomography and Computed Tomography.

Failure of fixation is a potential complication associated with surgical implants, and early detection is important but challenging. Positron emission tomography (PET) has the potential to detect lesions that may exhibit little to no visible findings on other commonly used diagnostic imaging modalities. The aim of this retrospective descriptive study was to assess ¹⁸F-Sodium Fluoride (¹⁸F-NaF) uptake associated with surgical implants in dogs. Medical records were searched for canine patients with orthopedic metallic implants in place imaged with ¹⁸F-NaF PET/CT. PET images were reviewed blinded to clinical history, with each surgical implant assessed for the presence of increased radiopharmaceutical uptake (IRU). IRU was graded subjectively regarding the severity (absent, mild, moderate, severe) and the extent area (focal, multifocal, extensive), and objectively by measuring maximal standardized uptake values (SUVmax). Seven patients were included, with a total of 39 metallic implants used in eight surgical procedures (three total hip replacements, three humeral fractures, one tibial plateau leveling osteotomy, and one tibial tuberosity advancement). In 24 of 39 implants (62%), no IRU was displayed. Fifteen implants (38%) displayed IRU (five mild, five moderate, five severe). The highest SUVmax (24) was associated with confirmed sepsis of a total hip replacement implant. The remaining implants with severe IRU were articular implants with associated marked degenerative joint pathology. This study confirms that most implants displayed no IRU with ¹⁸F-NaF PET. The presence of implant-associated IRU may indicate implant failure; however, IRU may also be due to regional bone pathology, including both degenerative joint disease and sepsis.