The triquetral fracture is a break in the triquetrum, one of the small, pyramid-shaped bones located in the wrist. This bone is situated in the proximal row of the eight carpal bones connecting the forearm to the hand. Triquetral fractures are relatively common wrist injuries, representing the second most frequently fractured carpal bone after the scaphoid. They account for approximately 15% to 18% of all carpal bone fractures. Understanding the location and injury mechanism is key to proper diagnosis and effective treatment.
Anatomy and Common Causes of Injury
The triquetrum is positioned on the ulnar side of the wrist (closest to the pinky finger), sitting between the lunate and pisiform bones. It does not directly articulate with the ulna but connects via the triangular fibrocartilage complex. This placement exposes the triquetrum to unique forces, leading to two main injury mechanisms.
The most frequent cause is a fall onto an outstretched hand (FOOSH injury), where the wrist is extended and deviated ulnarly. This mechanism typically results in a dorsal chip fracture, also called an avulsion fracture, where a ligament shears off a small fragment from the back surface of the triquetrum. A less common but more severe injury is a body fracture, which involves a break through the main mass of the bone. Body fractures usually result from high-energy trauma or a direct impact to the wrist.
Recognizing the Symptoms
A triquetral fracture typically presents with immediate, noticeable signs following the traumatic event. The most common symptom is localized pain concentrated on the dorsal and ulnar side of the wrist (the back of the hand near the pinky finger). This discomfort is often accompanied by swelling directly over the injury site.
Patients frequently experience tenderness when touching the triquetrum area. Moving the wrist, particularly bending it backward or forward, often exacerbates the pain. Patients may also notice a reduced ability to grip objects or general weakness when attempting to bear weight on the hand. Recognizing these localized symptoms after a fall or impact indicates that medical attention should be sought promptly.
Diagnosis and Classification of Triquetral Fractures
The diagnostic process begins with a careful physical examination to assess the location of tenderness and the wrist’s range of motion. Medical imaging is necessary to confirm the fracture and determine its type. Standard X-rays are the initial imaging method, but identifying a triquetral fracture can be challenging due to the bone’s small size and overlap with neighboring carpal bones.
A lateral X-ray view is especially informative, as it often reveals the small bone fragment characteristic of a dorsal chip fracture lying just behind the triquetrum. If the X-ray is inconclusive, or if a complex body fracture or associated ligament injury is suspected, a Computed Tomography (CT) scan may be ordered. A CT scan provides detailed cross-sectional images that clearly delineate the fracture lines and the degree of bone displacement.
The fracture classification guides the subsequent treatment strategy. The majority of injuries are stable dorsal chip fractures, involving a small fragment pulled off the surface. Conversely, body fractures are less common but are more serious because they can be unstable and sometimes associated with a dislocation of other carpal bones, compromising wrist stability.
Treatment Pathways and Recovery
The treatment protocol for a triquetral fracture depends on its classification and stability. Most dorsal chip fractures are stable and managed non-surgically. This conservative approach involves immobilizing the wrist, typically with a short-arm cast or a splint, for a period ranging from three to six weeks.
Non-displaced body fractures also usually heal well with a similar period of immobilization to allow the bone to consolidate. For significantly displaced body fractures or those associated with carpal instability, surgical intervention may be required. Surgery often involves open reduction and internal fixation (ORIF), where the bone fragments are physically realigned and held in place with pins or screws.
Following the period of immobilization, physical therapy is a necessary part of the recovery process to restore strength and full range of motion to the wrist. For most uncomplicated fractures, pain typically subsides within six to eight weeks, with a full return to normal activity often achieved within two to three months.