Using MR imaging to differentiate peroneal splits from other peroneal disorders

Peroneal splits syndrome is the result of repetitive subluxations that lead to longitudinal tears of the peroneus brevis tendon. The purpose of this study was to use MR imaging to differentiate the characteristics of peroneal splits syndrome from other peroneal disorders.

Forty-two ankles in 39 patients (age range, 10-70 years old) clinically diagnosed with peroneal tendon disorders were studied with 1.5-T MR imaging. Two independent, blinded observers evaluated the peroneal tendons in these 42 ankles for evidence of altered morphology, increased intratendon signal intensity on T2-weighted images, volume of fluid within the peroneal tendon sheath, shape of the fibular peroneal groove, sharp posterolateral margin of the distal fibula, and subluxation or dislocation at the time of imaging. Surgical-clinical correlation provided the diagnosis.

Peroneal splits were confirmed at surgery in 20 ankles. The MR findings were bisected peroneus brevis tendon (p < .0001), convex or flat fibular groove (p = .03), and spur on the edge of the groove (p = .002). Increased fluid in the peroneal tendon sheath was seen in only 55% (p = .099) of these ankles, and hypertrophied peroneus longus tendon was seen in only 15%. Increased intratendon signal intensity on T2-weighted sequences within either the peroneus brevis tendon or the peroneus longus tendon was seen in patients with peroneal splits (60%) (p = .296) as often as in patients without peroneal splits (59%). Subluxation was slightly more common in patients with peroneal splits (25%) than in patients without (18%).

Peroneal splits syndrome shows with a high frequency a bisected peroneus brevis tendon, a convex or flat fibular groove, and a posterolateral marrow-containing fibular spur.