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Age / Sex : 52 / M
Age/Sex: 52/M
C.C.: Pain in lateral malleolar area and anterior ankle joint
Hx: Rt. Calcaneal fracture (1 YA)
1) What is your impression?
Courtesy : Soo-Jung Choi, MD Department of Radiology, GangNeung Asan Hospital
Diagnosis: peroneal tendon subluxation /dislocation
Discussion
Findings:
Sequential proton density weighted axial images show blurring and thickening of the superior peroneal retinaculum. Peroneal longus tendon, which is normally located in retromalleolar area, has subluxed laterally. Proton density weighted axial image with ankle inversion shows obvious dislocation of peroneal longus tendon, anterolaterally.
Diagnosis: Dislocation of peroneal longus tendon with superior peroneal retinacular injury.
Discussion:
• 0.3-0.5 % of traumatic events to the ankle
• Mechanism
– Acute dislocation: sudden dorsiflexion of foot with concomitant violent contraction of peroneal muscles stripping of SPR from its distal fibular attachment lateral dislocation of peroneal tendons out of retromalleolar groove
– Chronic dislocation: chronic ankle instability a/w superior peroneal retinacular laxity
– Congenital foot deformities, crowding of retromalleolar groove by peroneus quartus muscle or low-lying peroneus brevis muscle belly, fracture of distal tibia and calcaneus
• MR imaging;
axial – Tendons to be located anterior and lateral to distal fibula
– Within “pouch” formed by stripped-off SPR
– Rarely, avulsion off distal fibula and midsubstance tears of SPR Tenosynovitis or tears of peroneal tendons, convex fibular groove, avulsion fracture of distal fibula, and tear of lateral collateral ligament
Association with calcaneal fracture and subluxation/dislocation of peroneal tendon
33 ~ 47% of calcaneal fractures revealed peroneal tendon subluxation or dislocation. (Ebraheim NA, et al. J. Orthop Trauma. 1991; 5:365-369 Bradley SA, et al. Br J Radiol. 1992; 65:105-11 Bradley SA, et al. Br J Radiol. 1990; 63:926-33)
References:
1) Wang XT, Rosenberg ZS, Mechlin MB, Schweitzer ME. Normal Variants and Diseases of the Peroneal Tendons and Superior Peroneal Retinaculum: MR Imaging Features. Radiographics 2005; 25:587-602
2) Rosenberg ZS, Beltran J, Bencardino JT. MR Imaging of the Ankle and Foot. Radiographics 2000; 20:S153-S179
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