• Pearl: The scaphoid is the most frequently fractured carpal bone [1,2].
• Pearl: Fractures occur at the waist, proximal third, and distal portion: 65%, 25%, and 10% respectively [3].

Image 2. Fracture of scaphoid. Case courtesy of Dr. Hani Makky ALSALAM, Radiopaedia.org, rID: 10398 (arrow added by authors).

Occurs when there is an axial load across hyper-dorsiflexed, pronated and ulnar deviated wrists or from a fall on the outstretched hand (FOOSH) [1-3].

Snuff box tenderness, scaphoid tubercle tenderness over the volar aspect of the wrist, and/or positive scaphoid compression test (pain reproduced with an axial load applied through thumb metacarpal) [4-6].

Image 3. Location of scaphoid tubercle (S) at the base of the thenar eminence (left) and the location of the snuffbox (SB) on the radial aspect of the wrist (right). Images by authors.

Plain film imaging with anterior-posterior, oblique, and lateral views to assess for injury.

• Pearl: There is also a scaphoid view that is recommended if the department technician is trained. This image is a posterior-anterior view of the scaphoid that is obtained with the wrist in ulnar deviation [7].

Abnormal exam: If not neurovascularly intact or if there is an open fracture, consult orthopedics in the ED.

Identified scaphoid fracture: Thumb spica splint and prompt orthopedic follow-up usually within 1-3 days as though some fractures only require immobilization for treatment; surgery may be required for some fracture patterns [1-3,6].

Suspicion for fracture without radiographic evidence: Place in thumb spica splint and repeat imaging in 14 days to evaluate for occult fracture. If negative again at that time with high clinical suspicion, the patient should have an outpatient MRI [1-3,6].

• Pearl: Initial imaging can miss 5-20% of fractures [8].

Classic complications include vascular necrosis (AVN), and scaphoid nonunion advanced collapse (SNAC). Associated fractures and dislocation of the surrounding carpal bones, distal radius, ligamentous disruption may be seen as other pathology occurs secondary to a FOOSH [1-4,6].

• Pearl: AVN is of high concern and directly correlated to the site of fracture. The scaphoid receives blood supply via retrograde flow – the more proximal the fracture, the higher the risk of AVN [1-4,6].
• Pearl: SNAC occurs when the proximal scaphoid remains attached to the lunate and the distal fragment rotates into flexion. This results in early osteoarthritis between the distal scaphoid and radial styloid, leading to pain and decreased functionality [9].

This is a proximal avulsion fracture of the styloid process of the fibula, indicating injury to the posterolateral corner (PLC) of the knee [1].

• Pearl: In most cases, the avulsed fragment is attached to the lateral collateral ligament and/or the biceps femoris [2].

This injury usually occurs from varus stress in a hyperextended knee- think a blow to the anteromedial tibia with the knee in extension [2].

The arcuate sign is a horizontal linear lucency through the head of the fibula that represents a fracture of the styloid process [3].

• Pearl: This injury may be confused with a Segond fracture, which is a small avulsion fracture fragment from the lateral tibial plateau associated with anterior cruciate ligament injury.

A proximal fibular avulsion fracture is commonly associated with injury to the posterior cruciate ligament, anterior cruciate ligament, popliteus, or meniscus. It is frequently seen with bone contusions and sometimes a tibial plateau fracture [2].

• Pearl: Injury to the common peroneal nerve may occur as well. Remember to perform a thorough neurovascular examination [1].
• Pearl: This fracture is a sign of posterolateral instability and likely internal derangement of the knee. Outpatient MRI can be used to evaluate the soft tissue components of the injury and diagnose associated injuries [2].

This injury indicates potential significant instability of the knee and requires outpatient follow-up with MRI. Operative management will be dictated on an individual basis, after evaluating MRI results. In the emergency department, place the patient in a knee immobilizer and recommend non-weight-bearing status until further imaging. Follow-up with orthopedics or sports medicine within 1 week.

• Pearl: As always, perform a thorough neurovascular examination and consult orthopedics immediately if there is evidence of compromise. If your exam demonstrates significant instability and you are concerned about a spontaneously-reduced knee dislocation, consider ankle-brachial indices and/or further vessel imaging.

If diagnosis of this injury is delayed, posterolateral instability may develop. If not recognized and managed appropriately, this may hinder the success of a cruciate ligament reconstruction [1].