Fluid around the distal tibialis posterior tendon on ankle MRI: prevalence and clinical relevance

Abstract

Objective: It has been stated that the distal 1–2 cm of the tibialis posterior tendon (TPT) does not have a tendon sheath but rather a paratenon, and that any fluid seen around this segment on ankle MRI is considered to represent paratendonitis. The prevalence and clinical significance of isolated TPT paratendonitis diagnosed on ankle MRI is unknown. This study aims to correlate the presence of isolated distal segment TPT paratendonitis on ankle MRI, with the presence or absence of medial midfoot pain. Methods: A retrospective database of 195 consecutive 3 T ankle MRI studies was assessed for the presence of isolated TPT paratendonitis. Relevant clinical notes were available in 159 of these cases, and were reviewed for the absence or presence of medial midfoot pain. Results: Of 133 patients with both ankle MRI studies and clinical notes available, 53 (33.3%) patients had isolated TPT paratendonitis based on MRI. Of these, 37 (69.8%) had reported no medial foot pain on review of clinical records, while medial foot pain was recorded in 16 cases (30.2%). The comparison of TPT paratendonitis with clinically evident medial midfoot pain showed no statistically significant association (p = 0.19). Conclusion: Fluid signal intensity around the distal 1–2 cm of the TPT is a relatively common finding on ankle MRI. Therefore, care should be taken when reporting ankle MRI studies not to overstate the relevance of this finding. Advances in knowledge: There was no statistically significant relationship between medial midfoot pain and the presence of isolated TPT paratendonitis.