In alpine summer ES trauma, imaging should not be guided only by the most evident painful region, but by the combination of clinical severity, mechanism of injury, and expected pattern of associated lesions. A mechanism-based approach is particularly important because patients injured during extreme sports may present with focal symptoms despite multiregional trauma. High velocity, abrupt deceleration, vertical impact, axial loading, and direct collision with irregular surfaces can produce clinically occult injuries, especially involving the spine, pelvis, thorax, abdomen, and head [9, 11].

For the purposes of this pictorial essay, “high-energy mechanism” refers to trauma in which the amount or direction of energy transfer raises concern for clinically significant injury beyond a single anatomic region. In alpine summer sports, this includes high-speed downhill biking crashes, over-the-handlebar impact, collision against rocks or trees, hard landings after aerial sports, falls during climbing or canyoning, ejection from a raft, and trauma associated with loss of consciousness, neurologic deficit, respiratory compromise, hemodynamic instability, or pain in multiple body regions [3,4,5,6,7,8,9, 12,13,14,15,16,17,18,19,20]. Similarly, “fall from height” should be considered a mechanism rather than a purely numerical threshold. Injury severity depends not only on the measured height, but also on landing posture, impact surface, velocity, protective equipment, axial loading, and secondary impacts against rock, ground, water, trees, or artificial structures [9, 11, 21].

In stable or stabilized patients with suspected major blunt trauma or multiregional injury, whole-body computed tomography (CT) is the key modality because it rapidly evaluates the head, spine, chest, abdomen, and pelvis in a single integrated examination. This approach is particularly relevant when the clinical examination is unreliable, when the mechanism is high energy, or when injuries in different body regions may coexist after axial loading or deceleration [22,23,24,25].

Radiography remains appropriate for stable patients with isolated appendicular trauma and low suspicion of multisystem injury. However, CT should be used when fracture anatomy is complex, intra-articular, radiographically occult, or relevant for operative planning, and when the mechanism suggests associated injuries outside the field of the initial radiographs [10, 11, 22].

Magnetic resonance imaging (MRI) has a complementary role and is usually performed after initial stabilization rather than during the primary assessment of unstable trauma. Its main indications include suspected spinal cord injury, ligamentous disruption, epidural hematoma, marrow edema, traumatic axonal injury, and neurologic symptoms that are unexplained or underestimated by CT [21, 22, 26].

Water-related ES trauma requires additional attention because traumatic and non-traumatic complications may coexist. In canyoning and rafting, blunt impact injuries may be associated with submersion, aspiration, hypothermia, near-drowning-related pulmonary complications, and hypoxic brain injury, so imaging should be guided by both trauma severity and respiratory or neurologic status [5,6,7,8, 21, 24].

Table 1 translates these principles into a general imaging algorithm for emergency practice. The following sport-specific sections apply this general algorithm to the characteristic mechanisms encountered in alpine summer ESs.

Among ground-based alpine summer ESs, DH-MTB is dominated by velocity, abrupt deceleration, and direct impact, making the mechanism closer to high-energy cycling trauma than to low-energy recreational bicycle injuries. DH-MTB involves descent on steep, rough, and technical terrain with rocks, roots, jumps, and drops. Falls, collisions, and abrupt deceleration produce frequent traumatic injuries, particularly involving the extremities [12, 13]. Lateral falls commonly affect the shoulder girdle, clavicle, arm, and ribs, whereas forward falls over or onto the handlebars may cause craniofacial, thoracic, abdominal, and upper-extremity trauma [12, 13]. Sudden deceleration can transmit axial and shear forces to the head, spine, pelvis, and limbs [4, 14].

DH-MTB injuries range from minor skin abrasions and contusions to moderate skeletal trauma, most commonly fractures [12, 13]. Severe injuries are less frequent but may include hemorrhagic concussion, vertebral fractures with or without spinal cord injury, and internal organ damage with bleeding [4, 14]. The lower leg and forearm are among the body regions most often affected [12, 13].

From a radiological perspective, conventional radiographs are appropriate as the initial examination for suspected isolated fractures, whereas CT is essential when injury to the spine, pelvis, or thorax is suspected [14, 22]. Particular attention should be paid to fractures of the clavicle, radius, femur, and ribs, as well as spinal compression fractures, craniofacial trauma, and intracranial injury [4, 12,13,14] (Figs. 2, 3 and 4).

Contrast-enhanced CT images of a 37-year-old patient after a right-sided fall during down-hill mountain biking demonstrate a laceration-contusion injury of the right kidney (A), with disruption of the urinary collecting system and extravasation of contrast-opacified urine (yellow arrow, B)

Contrast-enhanced chest CT of a 55-year-old man involved in a high-energy down-hill mountain biking accident, with direct handlebar impact causing a penetrating injury to the left anterior hemithorax. Axial and coronal images show left-sided pneumothorax (A, B, D), rib fractures (B), pulmonary laceration-contusion (A), and pleural effusion with heterogeneous attenuation, consistent with a partial hematic component (yellow arrow, C)

Imaging of a 54-year-old man following high-energy down-hill mountain biking trauma against trees. Head CT demonstrates bilateral frontal cerebral contusions with associated traumatic subarachnoid hemorrhage (A, B). Bone-window maxillofacial CT shows complex comminuted facial fractures (C, D). Cervical spine CT and MRI reveal a hyperextension mechanism injury (E, F), including MRI findings suggestive of early C5–C6 disco-ligamentous injury/distraction (yellow arrow, F)