Presentation
Teenage high level soccer player with one year of relapsing big toe pain, right worse than left. Clinically feet are in equinus and bilateral big toes are normally held in dorsiflexion when running.
Patient Data
DP WB views of the feet
Bilateral DP views and right oblique foot view shows marked sclerosis of the epiphyses of the proximal phalanges of the big toes. The right big toe proximal phalangeal epiphysis is fragmented with a central cleft. The epiphyseal fragment is displaced. Appearances are consistent with Salter-Harris type III stress fractures.
MRI of the right forefoot.
The right foot base of big toe proximal phalanx epiphysis is fragmented irregular, sclerotic and shows a bow tie appearance. There is a central cleft in the epiphysis. The epiphyseal fragments are displaced and growth plate high signal is effaced. This is an unusual case of a Salter Harris type III stress fracture. Note the pointed morphology of the first metatarsal head. The hyperextended big toe has resulted in a pilon type driving force through the first metatarsal head into the central aspect of the epiphysis of the base of the proximal phalanx of the big toe. Repetitive microtrauma has resulted in the epiphysis fracturing and displacing. The lack of bone marrow edema and effacement of the growth plate signal suggests this has partially united in situ.
There is a full thickness first metatarsophalangeal joint plantar plate chronic tear. Note how normal the sesamoids are. This is because the sesamoids are not involved in the line of force.
Also note the bone marrow edema (BMO) in the epiphyses of the second to fifth metatarsal heads. The BMO abuts the growth plates. These are known as focal peri-physeal edema zones (FOPE zones) and are indicative of stress reactions around the growth plates.
Case Discussion
Stress fractures around the growth plates are becoming a common injury seen in the young athlete. This case is a relatively unusual Salter-Harris type III stress fracture in a teenage soccer player with pre-existing foot morphological changes. The case illustrates three salient points:
The importance of the clinical presentation and the clinical examination on how to report the MRI case. In this case, the teenager has pre-existing foot problems that explain the MRI findings.
The importance of reviewing the previous imaging and correlating the findings with the MRI that is being reported. Radiographs are an important adjunct to accurate reporting of MRI studies in musculoskeletal radiology. In this case, the radiographs with the relevant clinical history may have been sufficient to explain the patients symptoms.
Understanding the biomechanics involved in producing the imaging findings. Here the hyperextension of the big toe MTPJ, the pointed morphology of the first metatarsal head and the pes equinus all play a role in the pathology.
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