Acute Medial Ankle Pain in a 17-Yr-Old Basketball Player.

Abstract

This study conforms to all case report guidelines and reports the required information accordingly (see Supplementary Checklist, Supplemental Digital Content 1, https://links.lww.com/PHM/B586). A 17-yr-old male collegiate basketball player with no medical history presented one day after developing new-onset left medial ankle pain during a practice in which he took 700 consecutive jump shots. The pain progressed, eventually limiting his ability to bear weight. He denied any previous left lower limb injuries. Pertinent physical examination findings included focal tenderness over the distal tibia 4 cm proximal to the medial malleolus, pain with passive dorsiflexion/eversion, and pain with both resisted plantarflexion/inversion and toe flexion. There was no adjacent erythema or effusion about the ankle present. The differential diagnosis included distal tibia stress reaction/fracture, posterior tibialis (PT), or flexor digitorum longus (FDL) tendinopathy, and flexor retinaculum injury. Radiographs were negative. Magnetic resonance imaging (MRI) demonstrated fluid signal and edema about the distal PT and FDL myotendinous junctions, with grossly normal-appearing tendons (Fig. 1).FIGURE 1: Axial oblique (A and B) and sagittal oblique (C) T2-weighted MRI of the left ankle demonstrating fluid signal and edema about the distal PT and FDL myotendinous junctions (arrows) within the distal medial lower leg. Panel D demonstrates corresponding AP plain films of the left ankle. Ant, anterior; EDL, extensor digitorum longus; EHL, extensor hallucis longus; FHL, flexor hallucis longus; G-S-A, gastroc-soleus-Achilles complex; Inf, inferior; Lat, lateral; Med, medial; PB, peroneus brevis; PL, peroneus longus; Post; posterior; Sup, superior.The final diagnosis was chiasma crurale intersection syndrome. After MRI ruled out bone stress injury (no evidence of periosteal or bone marrow edema), he was started on a 7-day course of oral ibuprofen 400 mg 3 times daily. He was weaned from his walking boot over the course of 5 days guided by pain-free ambulation, after which he started progressive strengthening. Ibuprofen was not recommended until after the MRI to minimize possible impairment in bone healing, had there been a stress injury. At 3 wks after injury, he had returned to play without symptoms. Chiasma crurale refers to the intersection of the PT and FDL tendons. A symptomatic intersection syndrome at the crossover of these two tendons has not been previously reported. Theoretically, an intersection syndrome can develop at any point where two tendons cross and have no tendon sheath or paratenon separating them, as this predisposes them to increased friction forces and inflammation in the setting of overuse. Intersection syndromes elsewhere in the body have been reported, most notably where the 1st dorsal extensor compartment crosses over the 2nd in the forearm.1,2 Diagnosis can be confirmed through MRI or ultrasound. Ultrasound findings in intersection syndromes include anechoic fluid with loss of the hyperechoic plane separating the tendons and possible increased power Doppler signal.3,4 Cadaveric studies have found that the chiasma crurale has no intervening tissue at its center, making it a potential site for an intersection syndrome.5 On average, its center is located 4.2 cm above the tibiotalar joint.5 Gross irregularities of the tendons at the chiasma crurale may be seen on imaging, without histologic evidence of tendon degeneration.5 When this is the case, a concurrent symptomatic PT tendinopathy should be considered and clinically evaluated for, although classically that pain is present closer to the tendon’s distal insertion. Treatment of intersection syndromes is similar to that of other overuse conditions. Initially, activity modification and load management education are implemented, followed by progressive mobilization, strengthening, and incorporation of sport-specific activities in athletes.6 For cases recalcitrant to the above measures, a corticosteroid injection can be considered. Surgical release and debridement of inflamed tenosynovium are rarely needed but remain an option when nonoperative measures have been exhausted. TEACHING POINTS Chiasma crurale refers to the intersection of the PT and FDL tendons in the posteromedial distal leg. Magnetic resonance imaging findings of fluid signal and edema about the distal PT and FDL myotendinous junctions within the distal lower leg, coupled with grossly normal-appearing tendons, suggest inflammation from an intersection syndrome. Chiasma crurale intersection syndrome is a rare cause of medial ankle pain and is generally responsive to conservative treatment.