Trans-ulnar fracture dislocations of the elbow: a systematic review and clarification of classification systems.

BACKGROUND: Complex elbow dislocations in which the dorsal cortex of the ulna is fractured can be difficult to classify and therefore treat. These have variably been described as either Monteggia variant injuries or trans-olecranon fracture dislocations. Additionally, O'Driscoll et al classified coronoid fractures that exit the dorsal cortex of the ulna as "basal coronoid, subtype 2" fractures. The Mayo classification of trans-ulnar fracture dislocations categorizes these injuries in 3 types according to what the coronoid remains attached to: trans-olecranon fracture dislocations, Monteggia variant fracture dislocations, and trans-ulnar basal coronoid fracture dislocations. The purpose of this study was to evaluate the outcomes of these injury patterns as reported in the literature. Our hypothesis was that trans-ulnar basal coronoid fracture dislocations would have a worse prognosis. MATERIALS AND METHODS: We conducted a systematic review to identify studies with trans-ulnar fracture dislocations that had documentation of associated coronoid injuries. A literature search identified 16 qualifying studies with 296 fractures. Elbows presenting with basal subtype 2 or Regan/Morrey III coronoid fractures and Jupiter IIA and IID injuries were classified as trans-ulnar basal coronoid fractures. Patients with trans-olecranon or Monteggia fractures were classified as such if the coronoid was not fractured or an associated coronoid fracture had been classified as O'Driscoll tip, anteromedial facet, basal subtype I, or Regan Morrey I/II. RESULTS: The 296 fractures reviewed were classified as trans-olecranon in 44 elbows, Monteggia variant in 82 elbows, and trans-ulnar basal coronoid fracture dislocations in 170 elbows. Higher rates of complications and reoperations were reported for trans-ulnar basal coronoid injuries (40%, 25%) compared to trans-olecranon (11%, 18%) and Monteggia variant injuries (25%, 13%). The mean flexion-extension arc for basal coronoid fractures was 106° compared to 117° for Monteggia (P < .01) and 121° for trans-olecranon injuries (P = .02). The mean Mayo Elbow Performance Score was 84 points for trans-ulnar basal coronoid, 91 for Monteggia (P < .01), and 93 for trans-olecranon fracture dislocations (P < .05). Disabilities of the Arm, Shoulder and Hand and American Shoulder and Elbow Surgeons scores were 22 and 80 for trans-ulnar basal coronoid, respectively, compared to 23 and 89 for trans-olecranon fractures. American Shoulder and Elbow Surgeons was not available for any Monteggia injuries, but the mean Disabilities of the Arm, Shoulder and Hand was 13. DISCUSSION: Trans-ulnar basal coronoid fracture dislocations are associated with inferior patient reported outcome measures, decreased range of motion, and increased complication rates compared to trans-olecranon or Monteggia variant fracture dislocations. Further research is needed to determine the most appropriate treatment for this difficult injury pattern.

A coronoid-centric classification system of proximal trans-ulnar fracture-dislocations has almost perfect intraobserver and interobserver agreement.

BACKGROUND: Fracture-dislocations of the elbow, particularly those that involve a fracture through the proximal ulna, are complex and can be difficult to manage. Moreover, current classification systems often cannot discriminate between Monteggia-variant injury patterns and trans-olecranon fracture-dislocations, particularly when the fracture involves the coronoid. The Mayo classification of proximal trans-ulnar fracture-dislocations categorizes these fractures into 3 types according to what the coronoid is still attached to: trans-olecranon fracture-dislocations (the coronoid is still attached to the ulnar metaphysis); Monteggia-variant fracture-dislocations (the coronoid is still attached to the olecranon); and ulnar basal coronoid fracture-dislocations (the coronoid is not attached to either the olecranon or the ulnar metaphysis). The purpose of this study was to evaluate the intraobserver and interobserver agreement of the Mayo classification system when assessing elbow fracture-dislocations involving the proximal ulna based on radiographs and computed tomography scans. METHODS: Three fellowship-trained shoulder and elbow surgeons and 2 fellowship-trained orthopedic trauma surgeons blindly and independently evaluated the radiographs and computed tomography scans of 90 consecutive proximal trans-ulnar fracture-dislocations treated at a level I trauma center. The inclusion criteria included subluxation or dislocation of the elbow and/or radioulnar joint with a complete fracture through the proximal ulna. Each surgeon classified all fractures according to the Mayo classification, which is based on what the coronoid remains attached to (ulnar metaphysis, olecranon, or neither). Intraobserver reliability was determined by scrambling the order of the fractures and having each observer classify all the fractures again after a washout period ≥ 6 weeks. Interobserver reliability was obtained to assess the overall agreement between observers. κ Values were calculated for both intraobserver reliability and interobserver reliability. RESULTS: The average intraobserver agreement was 0.87 (almost perfect agreement; range, 0.76-0.91). Interobserver agreement was 0.80 (substantial agreement; range, 0.70-0.90) for the first reading session and 0.89 (almost perfect agreement; range, 0.85-0.93) for the second reading session. The overall average interobserver agreement was 0.85 (almost perfect agreement; range, 0.79-0.91). CONCLUSION: Classifying proximal trans-ulnar fracture-dislocations based on what the coronoid remains attached to (olecranon, ulnar metaphysis, or neither) was associated with almost perfect intraobserver and interobserver agreement, regardless of trauma vs. shoulder and elbow fellowship training. Further research is needed to determine whether the use of this classification system leads to the application of principles specific to the management of these injuries and translates into better outcomes.