What are the concerns associated with a triquetral avulsion fracture?

Concerns with Triquetral Avulsion Fracture

Critical Diagnostic Concerns

The primary concern with triquetral avulsion fractures is that they frequently indicate significant underlying ligamentous injury and carpal instability, particularly when involving the volar surface, which can lead to chronic pain and dysfunction if missed. 1

Location-Specific Risk Stratification

• Dorsal cortical avulsion fractures (most common, 15-18% of all carpal fractures) are typically benign chip fractures from impaction after a fall on an outstretched hand, though they can be associated with triangular fibrocartilage complex (TFCC) injury 2, 3

• Volar triquetral avulsion fractures are the most problematic subtype and are easily missed on standard three-view radiographs, yet they signal severe perilunate ligament disruption 1

• Intra-articular fractures within the pisotriquetral joint can lead to pisiform subluxation, flexor carpi ulnaris dislocation, and late pisotriquetral arthritis 4

Associated Soft Tissue Injuries

Persistent ulnar-sided wrist pain after triquetral fracture treatment should raise immediate suspicion for TFCC injury, which occurs in a significant proportion of cases. 3

• Volar avulsion fractures specifically indicate lunatotriquetral ligament tears in 100% of cases based on arthroscopic evaluation, with 75% also having scapholunate ligament tears 1

• The volar capsular ligament remains attached to the avulsion fragment, creating a tethering effect that perpetuates instability 1

• Dorsal carpal ligament tears can accompany intra-articular pisotriquetral fractures 4

Imaging Pitfalls and Recommendations

Standard three-view wrist radiographs miss volar triquetral avulsions in 100% of cases initially; an instability series with oblique views is mandatory when clinical suspicion exists. 1, 4

Imaging Algorithm

• Obtain conventional radiographs with careful attention to positioning first, as recommended by the American College of Radiology 5

• Add oblique wrist radiographs and CT scan when intra-articular extension or body fractures are suspected 4

• Perform stress videofluoroscopy to detect lunatotriquetral and scapholunate joint instability, which demonstrates abnormal motion in all cases of volar avulsion 1

• MRI is essential for evaluating ligamentous injuries, with 92-100% sensitivity for detecting the specific ligament tears and their level of involvement 6, 1

• Wrist arthrography (CT or MR) has nearly 100% sensitivity for scapholunate ligament tears and approximately 100% sensitivity with 80% specificity for lunotriquetral ligament tears 5

Treatment Complications and Long-Term Outcomes

Even with appropriate treatment, volar triquetral avulsions result in persistent pain and carpal instability of variable severity in 100% of patients at one year, regardless of whether arthroscopic debridement or prolonged splinting was used. 1

Specific Complications to Monitor

• Non-union occurs frequently, particularly with volar avulsions and multiple simultaneous carpal avulsion fractures 2, 7

• Persistent ulnocarpal joint pain and tenderness after 2 months of conservative treatment indicates TFCC injury requiring arthroscopic evaluation 3

• Pisotriquetral arthritis develops as a late complication of intra-articular fractures 2, 4

• Loss of motion and arthrosis can result from inadequate initial evaluation and treatment 2

Management Approach

• Immobilize dorsal cortical fractures in a short-arm cast for 6 weeks, followed by progressive motion and strengthening for 5 weeks 4

• Surgical treatment is indicated for fractures with significant displacement or evidence of instability 2

• Arthroscopic partial TFCC resection and synovectomy should be performed when physical examination tests are positive for TFCC injury after failed conservative treatment 3

• Consider arthroscopic debridement versus prolonged splinting for volar avulsions, though both have suboptimal outcomes 1

Key Clinical Pitfall

The most dangerous error is dismissing a triquetral avulsion as a simple "chip fracture" without obtaining an instability series and advanced imaging to rule out perilunate ligament disruption, which fundamentally changes prognosis and management. 1