In the evaluation of a persistently painful total knee arthroplasty, a triphasic bone scan utilizing Technetium-99m (Tc-99m) MDP is ordered. What is the generally accepted post-surgical time frame during which a mildly increased, diffuse periprosthetic radiotracer uptake can be considered normal physiological bone remodeling rather than indicative of aseptic loosening?

Explanation:
The correct option is a. Technetium-99m MDP binds to areas of active osteoblastic activity. The surgical trauma, bony resection, and subsequent stress-transfer re-equilibration required to incorporate and stabilize a massive total joint implant naturally induce massive local bone remodeling. This intense remodeling process is completely normal and can cause diffuse, mild-to-moderate radiotracer uptake on a bone scan for up to 12 to 24 months after the index surgery. Therefore, a positive bone scan within the first year is highly non-specific and must be interpreted with extreme caution when evaluating for loosening or infection. Reference: Rubello D et al. Nuclear medicine imaging of prosthetic joint infections. Semin Nucl Med.