The patient twisted his right ankle when his moped was hit by a slow moving car.
The patient was hit from behind by a slow moving car while driving a moped and fell, twisting his right ankle. He was not wearing any protective gear. There was no significant past medical history.
On examination of his right ankle there was obvious deformity with the hind foot angulated medially (Fig. 1a). There were two superficial small abrasions over the lateral malleolus (Fig. 1b). The dorsalis pedis was well felt. There was no skin tenting or any distal neurovascular deficit.
Radiographs of the right foot and ankle showed a medial subtalar dislocation with dislocation of the talonavicular joint (Fig. 2). There was also a possible fracture of the talus and a chip fracture of the cuboid. The patient was sedated and closed reduction of the subtalar joint was achieved (Fig. 3). A below-knee back slab was applied. Post-reduction radiographs showed satisfactory reduction of the subtalar and talonavicular joints and the talus fracture. The fracture was treated in a non-weight-bearing below-knee cast for six weeks, followed by full mobilisation of the ankle and subtalar joint with physiotherapy. The follow-up was uneventful.
Subtalar joint dislocations are uncommon (1) and require a high degree of suspicion as lateral ankle views do not show the dislocation clearly. Subtalar joint dislocation is associated with talonavicular joint dislocation. An inversion injury of the foot causes the talus to lever over the sustentaculum tali and dislocates the talonavicular joint followed by subluxation and dislocation of the talocalcaneal joint. Low energy injuries causing pure subtalar dislocations, treated nonoperatively, have a better long-term outcome (2).
Letonoff et al. in their case report of internal fixation of a fracture of the posteromedial process of the talus, after a medial subtalar dislocation, show that internal fixation of these fractures may reduce post-traumatic arthritis to the ankle and subtalar joints (3). Bibbo et al. showed that CT scanning identified associated injuries better and suggested that it should be performed in all cases of subtalar dislocations (4). There have been reports (1,5) of subtalar joint stiffness, but generally subtalar joint dislocation does not affect the mobility of the patient much.
Medial subtalar dislocation of right foot
Based on the provided anteroposterior and lateral X-ray images of the ankle, as well as clinical photographs, there is evident soft tissue swelling and skin damage on the lateral side of the right ankle. The X-ray images show:
The clinical and imaging findings preliminarily suggest a severe twisting injury of the ankle, possibly involving subtalar joint and/or talonavicular joint dislocation. Since X-ray alone has limited ability to detect small bone fractures and related soft tissue injuries, a CT scan may be necessary to confirm whether any occult fractures or avulsion fractures are present.
Differential diagnosis primarily relies on the mechanism of injury, clinical presentation (local swelling, site of pain), and imaging findings. If accompanied by fracture, CT scans can better visualize subtle fracture lines and assist in determining the treatment plan.
Based on the patient’s injury history (foot twisting after a vehicular collision), evident malalignment of the subtalar joint on imaging, and clinical examination indicating severe foot pain and deformity, the most likely diagnosis is “Right Foot Subtalar Joint (Including Talonavicular Joint) Dislocation.” There is a possibility of associated small or occult fractures, and a CT scan is needed for confirmation. If the CT shows no distinct fracture, it would then be classified as a pure subtalar dislocation.
Progressive rehabilitation exercises should only begin after the acute phase has passed and with the clearance of the attending physician. The following suggestions may be carried out under the guidance of a professional physical therapist or physician:
If the patient has other special conditions (such as osteoporosis or poor cardiopulmonary function), training intensity and methods should be further individualized to ensure safety.
This report is based on the existing medical history and imaging data for reference analysis. It cannot replace an in-person consultation or professional medical advice. The patient should seek timely medical evaluation, combining clinical examination and other auxiliary tests to determine the final diagnosis and treatment plan.
Medial subtalar dislocation of right foot
