summary Triquetrum fractures are common carpal fractures that are often associated with other injuries to the wrist. Diagnosis is confirmed with orthogonal views of the wrist. Treatment is generally nonoperative but injuries associated with wrist instability require surgical fixation. Epidemiology Incidence second most common carpal bone fracture accounts for up to 15% of all carpal fractures Associated conditions perilunate dislocations (seen in 12-25% of triquetral fractures) radius or ulna fractures Etiology Pathophysiology mechanism of injury dorsal cortical fractures impaction most common mechanism usually a fall onto wrist in dorsiflexion and ulnar deviation ulnar styloid can act as a chisel driven into the dorsal cortex of the triquetrum avulsion results from extreme palmar flexion with radial deviation due to attachment of dorsal radiotriquetral and triquetroscaphoid ligaments shearing force results from shearing of proximal edge of the hamate against the distal dorsal triquetrum during wrist extension body fractures sagittal fractures results from axial dislocations or anterior-posterior crush injury medial tuberosity fractures results from direct blow transverse proximal pole fractures associated with perilunate dislocations transverse body fractures associated with perilunate dislocations comminuted fractures results from high-energy trauma palmar cortical fractures avulsion of palmar ulnar triquetral ligament and LTIO ligament shearing force from pisiform Anatomy Osteology triquetrum is a wedge-shaped carpal bone located in the proximal row articulates with hamate pisiform lunate Ligaments extrinsic ulnotriquetral ligament originates from the palmar aspect of the triangular fibrocartilage complex (TFCC) inserts on the palmar aspect of the triquetrum dorsal radiotriquetral (radiocarpal) ligament originates from the dorsal distal radius inserts on the dorsal ridge of the triquetrum intrinsic palmar and dorsal lunotriquetral ligaments palmar ligament is thicker and stronger distal fibers blend with scapholunate ligament to form palmar and dorsal scaphotriquetral ligaments triquetrocapitate and triquetrohamate ligaments blend with ulnocapitate ligament to form ulnar arm of arcuate ligament dorsal intercarpal ligament originates from ulnar aspect of dorsal triquetrum inserts on dorsal rim of the scaphoid, trapezium, and trapezoid Blood Supply receives blood supply from nutrient arteries to non-articular surfaces Classification Triquetrum Fractures Classification Dorsal cortical fractures Most common (accounts for up to 93%) Mechanism includes avulsion, shearing force, or impaction Body fractures Second most common Subtypes: sagittal, medial tuberosity, transverse proximal pole, transverse body, comminuted Palmar cortical fractures Mechanism includes avulsion or shearing force Risk of instability Presentation Physical exam swelling/deformity of ulnar wrist pain with palpation directly over triquetrum pain with wrist flexion and extension if dorsal cortical fracture Imaging Radiographs recommended views PA lateral useful for visualizing dorsal cortical fractures IR oblique useful for visualizing dorsal cortical fractures optional views radial deviation may be helpful in identifying palmar cortical fractures findings "pooping duck" sign represents dorsal cortical fractures CT indications obtain if high suspicion of triquetral fracture MRI indications recommended for palmar cortical fractures due to concern for carpal instability obtain if concern for extrinsic intercarpal ligament injuries or occult fracture Differential Trapezial fracture Hook of Hamate fracture Pisiform fracture Lunate dislocation Diagnosis Radiographic diagnosis confirmed by history, physical exam, and radiographs Treatment Nonoperative immobilization for 4-6 weeks indications dorsal cortical fractures without evidence of instability nondisplaced body fractures palmar cortical fractures without evidence of instability Operative ORIF indications dorsal cortical fractures with evidence of instability displaced body fractures palmar cortical fractures with evidence of instability Techniques Immobilization for 4-6 weeks short arm cast with thumb free Open reduction internal fixation approach dorso-ulnar approach radial to ECU soft tissue longitudinal capsulotomy instrumentation interfragmentary screws suture anchors if ligamentous injury requiring repair K wires if instability Complications Non-union rare in triquetral body fractures can perform excision if symptomatic Persistent carpal instability Pisotriquetral arthritis