Magnetic resonance imaging detection of avascular necrosis in carpal bones despite apparent fracture union: a case series.

Assessment of fracture healing in carpal bones is commonly performed using computed tomography (CT). However, CT may not accurately reflect bone viability. Magnetic resonance imaging (MRI) is more sensitive in detecting early changes in bone marrow and vascularity. A diagnostic challenge arises when CT suggests fracture union while MRI demonstrates features of avascular necrosis (AVN). We conducted a retrospective case series of three patients with prior carpal bone fractures (one scaphoid and two lunate) who presented with persistent or new-onset wrist pain following apparent fracture healing. All patients underwent MRI evaluation, and a CT was performed in one case for correlation. Magnetic resonance imaging (MRI) demonstrated features suggestive of AVN in all three cases despite prior imaging indicating fracture union. Two cases showed T1 hypointensity with corresponding hyperintensity on fluid-sensitive sequences, consistent with early AVN, while one case demonstrated persistent low signal on both sequences, suggestive of chronic AVN. In the case of CT correlation, there was apparent fracture union with mild sclerosis and no evidence of collapse, highlighting discordance between structural and biological assessment. Hence, persistent wrist pain following a healed fracture should prompt MRI evaluation to assess bone viability and guide appropriate management.