25-year-old female with persistent posterior and lateral ankle pain for 7 months after twisting injury. History of remote navicular fracture and collapse (2 years ago) due to a car accident.
PD weighted non-fat suppressed axial, coronal and sagittal MR images of the ankle show a fracture of the entire posterior process of the talus, involving both medial and lateral tubercles. Posterior talofibular ligament including the posterior capsule were unremarkable.
The posterior process of the talus is comprised of the medial and lateral tubercles with a groove in between through which courses the flexor hallucis longus (FHL) tendon [1]. Fractures of the posterior talar process have only been described as case reports or case series, making it difficult to generalize the usual presentation, cause and associated symptoms [2]. Furthermore, these fractures usually involve an isolated fracture of either the medial or lateral tubercle and rarely involve simultaneous fracture of both tubercles [3].
Injuries to the FHL and subtalar dislocation in association with this fracture have been reported. The FHL tendon's position in the groove between the two tubercles can lead to its injury during repetitive plantar flexion or posterior ankle impingement leading to synovitis [4]. Additionally, fragment displacement can lead to interposition of this tendon between the fragments resulting in unsatisfactory healing [5]. Although very rare, posterior talar process fractures with associated subtalar joint dislocation have also been reported [6, 7] with the proposed mechanism being forced plantar flexion and inversion [7].
A fracture of either tubercle may mimic symptoms of ankle impingement while fractures of both tubercles are commonly misdiagnosed as ankle sprains [8]. It is important not to dismiss a fracture fragment located at the posterior aspect of the talus as a normal variant: an accessory ossicle called the os trigonum [9]. In addition to the os trigonum, an elongated lateral tubercle or Stieda's process may produce symptoms of posterior ankle impingement although no evidence of fragmentation is seen in this entity. Although conventional radiographs may reveal both the accessory ossicle and Stieda's process, further evaluation is required to confirm if these are in fact the source of associated symptoms. CT can demonstrate a fracture not evident on conventional radiographs while MR may reveal additional causes of internal derangement such as posterior ligamentous or posterior capsular abnormalities [10].
Fractures of both tubercles will usually be treated by conservative measures such as non-weight bearing and immobilization [9, 10]. Surgical reduction and fixation need to be considered in cases where the fragment is displaced, large or if there is persistent pain for more than 6 months [8]. Additionally, early recognition and operative management of this fracture are critical in athletes or active individuals such as snowboarders and rock-climbers where malunion or non-union can lead to early arthritis of both ankle and subtalar joints [7].
Symptomatic non-united fracture of the entire posterior process of the talus
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Based on the provided medical history and images (including MRI and diagrams), the main imaging characteristics include:
Based on the patient’s recurrent posterolateral ankle pain, history of sprain, suspected fracture in the posterior talar region indicated by MRI, and possible involvement of the FHL tendon groove, the following potential diagnoses are proposed:
Considering the patient’s 7-month history of persistent ankle pain, previous injuries, and MRI findings indicating involvement of the posterior talar process, the most likely diagnosis is:
“Posterior Talar Process Fracture (possibly involving the FHL tendon groove).”
To further delineate the size and degree of displacement of the fracture fragment, CT reconstruction may be considered. If diagnostic uncertainty remains, arthroscopic evaluation could be utilized as needed.
The treatment and rehabilitation plan should be individualized. For this particular patient:
During the recovery and subsequent rehabilitation phases, the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, and Progression) can be referenced:
Adjust the intensity and modalities of training based on patient bone density, cardiopulmonary endurance, and ankle stability. If pain worsens or new symptoms appear, seek medical advice or adjust the plan accordingly.
Disclaimer: This report provides a reference analysis based on available imaging and medical history, and it does not replace in-person evaluation or the advice of a professional physician. Specific treatment and rehabilitation plans should be tailored to the patient’s individual situation under the guidance of a professional healthcare team.
Symptomatic non-united fracture of the entire posterior process of the talus
