PERONEAL COMPARTMENT INJURIES :
Anatomy: Click here
Clinical Presentation:
Lateral ankle or hindfoot pain
Snapping sensation
Usually do not give history of trauma
Associated with RA, psoriasis, hypothyroidism, diabetes, local steroid injection.
Peroneal tenosynivitis:
Due to inversion injuries; lateral malleolar/calcaneal fracture; stress around the pulleys - retromalleolar groove, peroneal tubercle, cuboid undersurface
Around both tendons
Acute tenosynovitis is seen in athletes and ballet dancers. Seen as fluid around the peroneals. Stenosing tenosynovitis is due to synovial proliferation and fibrosis, causing diffuse int-to-low signal on all sequences. May enhance on Gd.
Associated marrow edema is uncommon
Treatment: rest, immobilization, anti-inflammatory medication, protected ambulation. Local anesthetic or peritendinous steroid injection for short-term benefits. Surgical decompression with chronic symptoms
Peroneus longus tendon rupture:
Persistent lateral ankle and plantar foot pain
Usually associated with peroneus brevis tear
Isolated tears common in midfoot - due to sports, calcaneal fracture, crushing injury to the calcaneocuboid joint, increased friction against either hypertrophic peroneal tubercle or cuboid bone, avulsion fracture of os peroneum
MR: thick and retracted tendon
Secondary changes on MR: hypertrophic peroneal tubercle, marrow edema of the peroneal tubercle, lateral calcaneal wall or cuboid bone
Treatment: Conservative treatment - anti-inflammatory medication, immobilization, cast, lateral ankle braces. Surgical treatment - debridement, repair, tenosynovectomy, removal of os peroneum, resection of hypertrophic peroneal tubercle
Peroneus brevis tendon rupture (peroneal split syndrome):
In young athletes/ elderly
More commonly iunjured than Peroneus longus
Susceptible to tear because it is between retromalleolar groove and peroneus longus and compressed between them during dorsiflexion
Predisposed by insufficiency of the superior peroneal retinaculum, thicken calcaneofibular ligament, crowded retromalleolar groove due to low-lying peroneus brevis belly, peroneus quartus, irregular retromalleolar groove, or peroneal tendon dislocation
Peroneus longus migrates anteriorly and may abut the fibular groove
Concomitant peroneus longus tear in up to one-third of peroneus brevis tears Axial: characteristic C-shaped configuration, the medial and lateral thick limbs partially enveloping peroneus longus with thin central portion (may be absent)
T1 and T2: Clefts, fragmentation, irregularity, increased signal
Grading not routinely used. Grade 1 splayed tendon without discrete tear. Grade 2 a partial-thickness split less than 1 cm. Grade 3 tear full-thickness split less than 2 cm. Grade 4 tear full-thickness split more than 2 cm.
Mimics: peroneus quartus and bifurcated peroneus brevis
Treatment: anti-inflammatory, rest, orthotic treatment, cast placement, surgical intervention (debridement, resuturing, attachment to the peroneus longus tendon). Associated superior peroneal retinaculum incompetence, irregular retromalleolar groove, crowding by accessory muscles may need surgical correction
Superior peroneal retinaculum injuries:
Most of the time associated with peroneal tendon dislocation
Due to sudden dorsiflexion with concomitant violent contraction of the peroneal muscles, leading to stripping of retinaculum from distal fibular attachment, leading to lateral dislocation of peroneal tendons from retromalleolar groove. Can also couur due to crowding of the retromalleolar groove by the peroneus quartus muscle or low-lying peroneus brevis belly, fractures of distal tibia and calcaneus.
Clinical presentation: ecchymosis, swelling, pain along lateral malleolus. May be mistaken for ankle sprain. Recurrent snapping sensation around ankle. Positive provocative tests
Grading (Oden’s classification):
Type I - elevation or stripping of retinaculum and periosteal attachment at fibular groove, forming a pouch into which the peroneal tendons can dislocate. Most common. Axial MR - pouch is seen as low signal with dislocated/subluxed peroneal tendons into the pouch. The pouch may collapse against the bone.
Type II - tear of retinaculum at distal fibula. Diagnosis on MR can be difficult, since the SPR is frequently thickened and poorly differentiated from the surrounding soft tissue in asymptomatics
Type III - avulsion fracture of retinaculum at distal fibula, 2nd most common.May be difficult to diagnose on MR, because avulsed bone fragment may not always be visualized. Secondary changes are lateral fibular bone defect and marrow edema at retromalleolar groove.
Type IV - tear of retinaculum at posterior attachment .
Treatment: Asymptomatic and static dislocation - no treatment. Casting in acute. Surgical treatment - groove deepening and soft-tissue reconstruction
Reference:
Wong XT et al. Normal variants and diseases of the peroneal tendons and superior peroneal retinaculum: MR imaging features. Radiographics 2005 May-Jun;25(3):587-602
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