MRI Appearance of Injured Ligament and Tendon of the Ankle in Different Postures: Study Protocol for a Single-center, Diagnostic Clinical Trial

The ankle joint is an important part of the human lower limb. It has the function of maintaining the normal standing of the human body, supporting and bearing the body weight and conducting movements. As one of the complex joints of the human body, its surrounding ligaments and tendons not only play an important protective effect on it, but also play a fixed role in the movement of the ankle to effectively prevent excessive ankle varus/valgus. Ankle fractures account for approximately 3.9% of total body fractures, ranking the first in intra-articular fractures. An ankle injury is often accompanied by intra-articular fractures and surrounding ligament rupture. With the increasing requirements for joint functions and clinical surgery, inappropriate treatment for ankle ligament injury can result in limited movement function of the ankle, and even lead to traumatic arthritis and chronic ankle instability.

X-ray examinations are routinely preferred for the diagnosis of ankle injury, which can make an accurate diagnosis of ankle dislocation and fracture. However, X-ray plain film has a low resolution for tendon and ligament lesions, which is easy to result in missed diagnosis of mild fractures, bone contusion and occult fractures, and moreover, it is difficult to fully clear the location, type and degree of ankle injury.

MRI has high definition and resolution to implement a multi-parameter multi-directional scanning. Its histopathological findings can accurately and objectively display ankle and surrounding ligament injuries and their severity. MRI is able to display the anatomic structure and severity of ligament injury of the ankle on three anatomic planes: transverse, sagittal and coronal. Sagittal MRI is a good helper for diagnosis of Achilles tendon lesion, which can clearly show the talus, posterior tibial tendon, talocalcaneal joint, Achilles tendon, subtalar joint, articulatio talonavicularis, tibiotalar joint, and the cartilage and joint cavities. Coronal MRI can clearly show structures of the peroneal joint, tibiotalar joint, and lateral malleolus, especially the articular surface between the tibia, fibula and the ankle bone as well as between the ligament fibula and the ankle bone; and meanwhile, it can display the posterior tibial ligament, posterior talofibular ligament and posterior tibial tendon. Transverse MRI well shows the tibiofibular ligament, and anterior talofibular ligament. The ankle ligament mainly consists of three parts: the lateral collateral ligament, medial collateral ligament and tibiofibular ligament. Activities of the ankle refer to flexion and extension along the sagittal plane, including plantar flexion and dorsiflexion, to play a role of supporting and bearing, movement conduction and function as a lever.

Adverse events If expected or unexpected adverse events (such as headache and nausea) during the MRI detection, the date of occurrence, type of injury and therapeutic managements will be recorded. Severe adverse events, including a requirement for immediate surgery, damage to patient's work ability, life-threatening events or death will be reported to the project manager and the institution review board within 24 hours.

Data collection, management, analysis and open access All data will be collected on a case report form, recorded electronically and saved in a dedicated computer. Continuous variables from each record will be collected for descriptive statistical analysis, to allow real-time review and identify any potential deviation.