Extremity CT and ultrasound in the assessment of ankle injuries: occult fractures and ligament injuries

Abstract

Objective: To assess the rates of fractures and ligament injuries in patients with an acute ankle injury and a normal radiographic examination, and to consider the most appropriate examination protocol. Methods: Patients with an acute ankle injury who presented to the John Radcliffe Hospital Emergency Department with a normal radiographic examination were eligible for the study. They were invited to receive a cone beam CT and ultrasound examination at a local radiology department within 5 days of their ankle injury. Results: Of the 100 patients recruited to the study, 19 patients were found to have major fractures and 42 patients had small avulsion fractures. Additionally, 42 patients had ankle effusions and there were a large number of soft tissue injuries. There were 83 acute injuries of the anterior talofibular ligament, 19 of the anterior tibiofibular ligaments, 26 of the calcaneofibular ligament, 39 of the deltoid ligament complex, 21 of the talonavicular ligament, 14 of the spring ligament and 3 of the calcaneocuboid ligament. Conclusion: Conventional radiographic examination misses significant fractures of the foot and ankle and the presence of an ankle effusion does not relate to the severity of injury. Ultrasound is a useful imaging technique that can supplement clinical practice, but it is unlikely to replace current protocols alone. Cone beam CT is an appropriate alternative to plain radiography, being more sensitive in detecting fractures and delivering a similar dose of radiation. However, neither CT or ultrasound examination can detect all avulsion fractures. Simple anterior process fractures of the calcaneus are associated with talonavicular ligament injuries and the medial ligaments are injured in almost 50% of cases when there is a lateral ligament injury. Advances in knowledge: Fractures in the foot and ankle are detected more precisely with cone beam CT compared to radiographs. Cone beam CT delivers similar doses of to conventional radiographs which is around 10% of that resulting from conventional CT. Ultrasound examination is an effective assessment tool to detect ligamentous injuries. The absence of an ankle effusion does not exclude a major fracture.

The diagnostic accuracy of ultrasound in the detection of foot and ankle fractures: a systematic review and meta-analysis

“…Because occult fractures account for 2%-36% in a conventional X-ray on account of overlapping structures, under-mineralized ossification centres and non-perpendicular X-ray beam to the fracture line [35]. Several studies have demonstrated that multiplanar capabilities of ultrasound might make it superior to radiography in the detection of occult fractures that the X-ray has missed [37,38]. Banal et al found that in cases of normal radiographs, US is indicated in the diagnosis of metatarsal bone stress fractures with a sensitivity of 0.83 and a specificity of 0.76 [18].…”

The Role of Pain Scoring in Multi-detector Computed Tomography Indications in Pediatric Occult Fractures

“…Although direct X-ray is accepted as the primary imaging modality in skeletal trauma, MDCT has become an important adjunct imaging method especially in the trauma of regions with a complex anatomy [12,13]. CT is not only used to better understand the fracture anatomy and make a surgical plan for both adult and child patients but also to investigate the occult pelvis, extremity, and vertebral fractures for which direct X-ray showed negative results [4,14,15]. It is often difficult to obtain a conventional radiographic series in trauma cases, and full-adaptation of patients to necessary positions cannot be achieved owing to pain.…”

Ultrasonography: Sports Injuries

“…The posterior tibiofibular and talofibular ligament can also be injured and assessed by ultrasound. Deltoid ligament injury is also common (in 50% of lateral ligament injuries) [32]. Dynamic assessment of all the ankle ligaments is possible with ultrasound including the posterior ligaments best seen using a small footprint.…”