A triquetral fracture is a break in the triquetrum, one of the eight small carpal bones in the wrist. This injury is categorized as a carpal fracture and is the second most frequently fractured bone in the wrist after the scaphoid bone. Triquetral fractures account for approximately 15% to 18% of all carpal bone fractures, making them relatively uncommon compared to forearm or hand injuries.
Understanding the Triquetrum Bone
The triquetrum is a small, pyramid-shaped bone located in the proximal row of the carpus (wrist bones). It sits on the ulnar side of the wrist, closest to the little finger, positioned between the lunate and the pisiform bones.
The triquetrum does not directly touch the ulna (the forearm bone on the pinky side). Instead, it connects to the ulna through the triangular fibrocartilage disc and various ligaments. It serves as an attachment point for multiple strong ligaments, including the dorsal radiotriquetral and lunotriquetral ligaments, which provide stability and contribute to the wrist’s range of movement.
How Triquetral Fractures Occur and Present
Triquetral fractures most commonly result from a fall onto an outstretched hand (FOOSH injury). The force of this impact, especially when the wrist is hyperextended and bent toward the little finger (ulnar deviation), causes the injury. This mechanism typically leads to two primary types of fractures: avulsion fractures and body fractures.
Dorsal cortical avulsion fractures are the most frequent, making up over 90% of all triquetral fractures. These occur when a strong ligament, such as the dorsal radiotriquetral ligament, pulls a small fragment of bone off the back (dorsal aspect) of the triquetrum. Body fractures involve the main structure of the bone. They are less common and typically result from higher-energy trauma, often associated with other serious wrist injuries.
A triquetral fracture typically presents with pain and swelling localized to the ulnar side of the wrist. Patients often feel tenderness directly over the dorsal surface of the triquetrum. Pain increases with movements like bending the wrist, making a fist, or attempting to grip an object.
Accurate Diagnosis of the Injury
Diagnosing a triquetral fracture can be challenging because the common avulsion fragments are often small and easily missed on standard X-ray views. Clinicians must maintain a high suspicion for this injury, especially after a fall onto an outstretched hand resulting in ulnar-sided pain. Initial imaging typically includes multiple X-ray views of the wrist.
The dorsal cortical fracture fragment is best visualized on a lateral view of the wrist, appearing as a small chip of bone separated from the main body. Specialized views, such as the 45-degree pronated oblique view, can also help highlight the fracture. If X-rays are inconclusive but clinical suspicion remains high, advanced imaging is necessary.
A Computed Tomography (CT) scan provides detailed cross-sectional images. CT scans are highly effective for detecting occult fractures (those not visible on X-ray) and for determining the exact extent of bone displacement. Magnetic Resonance Imaging (MRI) is used when there is concern for associated soft tissue injuries, such as tears to the surrounding ligaments. This is particularly relevant in the less common volar cortical fractures where carpal instability may be present.
Treatment Options and Recovery Outlook
The management of a triquetral fracture depends on the type and displacement of the break. The majority of dorsal cortical avulsion fractures are treated non-surgically because they are considered stable injuries. Non-surgical treatment involves immobilizing the wrist, typically with a short arm cast or a removable splint.
Immobilization is usually maintained for four to six weeks to allow the bone fragment to heal and the ligament attachments to settle. The primary goal of this initial phase is to reduce pain and prevent movement that could displace the fracture. Most patients experience a good outcome with this conservative approach.
Surgical intervention is rarely necessary. It is reserved for complex cases, such as significantly displaced triquetral body fractures or those associated with major ligamentous instability. For these severe breaks, surgery may involve open reduction and internal fixation, where fragments are realigned and held in place with pins or screws. Another surgical option for a persistently painful, non-healing small chip fragment is simple excision.
Following immobilization, physical therapy is an important component of the recovery process. Therapy focuses on restoring the full range of motion and strength in the wrist, as stiffness is a common temporary side effect of casting. Patients can expect a return to normal activities within eight to twelve weeks after the start of treatment. While complications like chronic pain or stiffness are possible if the injury is not properly managed, the overall prognosis is favorable because the triquetrum has a good blood supply, meaning avascular necrosis is not a concern.