Anterior tibial tendon abnormalities: MR imaging findings.

Purpose: To retrospectively evaluate the magnetic resonance (MR) imaging findings of anterior tibial tendon (ATT) abnormalities.

Materials And Methods: Institutional review board approval was not necessary for review of patient images and was granted for examination of the volunteers; informed consent was obtained. MR imaging findings in 28 consecutive patients (20 women, eight men; mean age, 63.2 years) clinically suspected of having an ATT abnormality were compared with those in an age- and sex-matched control group of 28 asymptomatic volunteers (20 women, eight men; mean age, 62.9 years). Surgical correlation was available for 11 patients. The short-axis diameter of the ATT and the longitudinal extent of signal intensity abnormalities were measured (Mann-Whitney U test). Signal intensity abnormalities of the ATT and irregularities of the underlying tarsal bones were analyzed in consensus by two blinded radiologists (chi2 test).

Results: In the symptomatic group, three cases of tendinosis and 13 partial and 12 complete ATT tears were diagnosed. In 11 cases (one case of tendinosis and two cases of partial and eight cases of complete ATT tear), surgical correlation was available and the MR imaging diagnosis was confirmed. In the asymptomatic group, four cases of tendinosis of the ATT were seen. The ATT diameter was significantly thicker in symptomatic patients at 1 cm (5.1 vs 3.1 mm in control group, P < .001), 3 cm (5.8 vs 3.4 mm, P < .001), and 6 cm (5.4 vs 4.3 mm, P = .006) proximal to the distal point of insertion. Most ATT abnormalities (in 23 [82%] of 28 patients) were located within the first 3 cm proximal to the insertion. Signal intensity abnormalities were seen in the anterior portion of the ATT in two (7%) of the 28 symptomatic patients and in the posterior portion in 11 (39%); diffuse involvement was seen in 15 (54%). Bone spurs on the navicular surface (nine [32%] patients vs no [0%] control subjects, P = .001), a ridged shape of the medial surface of the medial cuneiform bone (13 [46%] vs one [4%], P < .001), and osteophyte formation at the first tarsometasarsal joint (eight [29%] vs two [7%], P = .036) were significantly more common in the symptomatic patient group.

Conclusion: Characteristic findings of ATT abnormalities include tendon thickening (> or =5 mm) and diffuse or posterior signal intensity abnormalities of the tendon within 3 cm from the distal point of insertion.