The Montecranon classification-a comprehensive treatment strategy for complex proximal ulna fracture dislocations

Complex proximal ulna fracture dislocations include Monteggia-like fractures and transolecranon fracture dislocations. Since 2011, we introduced a structured classification and treatment algorithm for these fractures in a Swiss teaching hospital, considering ligamentous structures, the coronoid process, and the radial head. This classification, named the Montecranon classification (MC), was validated by users with varying experience levels through a retrospective clinical analysis.

All consecutive patients treated for a complex proximal ulnar fracture dislocation between 2011 and 2022 were retrospectively analyzed. Fractures were classified according to the Bado, Jupiter, Mayo, and the new MC.For the clinical study, patients treated according to the MC were retrospectively analyzed including final range of motion, EuroQol 5-Dimensions-5-Levels Score, Quick DASH, Mayo Elbow Performance Score, analysis of complications/revisions, and radiographic assessment for posttraumatic arthritis. Patients included had at least one year of clinical and radiographic follow-up.For validation, 22 randomly selected cases were sent to 4 elbow experts, 3 young consultants, and 3 novice doctors.

Of 43 patients (mean 55 years, range: 19-87) who suffered a complex proximal ulnar fracture dislocation, 30 patients met the inclusion criteria. Four patients (13%) had a transolecranon fracture dislocation, and 26 patients (87%) had a Monteggia-like fracture. The mean follow-up was 4.2 years (range: 1-10). At the final follow-up, the mean flexion-extension arc was 126° (range: 40-155), the mean Mayo Elbow Performance Score was 93 points (range: 70-100), and the mean qDASH was 19 points (range: 0-82). A total of 21 patients (70%) needed a secondary surgery after a mean of 364 days (range: 7-883). Whereof, hardware removal was performed in 12 (57%) patients. A significant correlation was found between decreased final range of motion and higher grade of MC fracture type.The interobserver correlation for MC was moderate for novice doctors and young consultants (kappa = 0.63 and 0.55) and poor for elbow experts (0.47). The intraobserver correlation was moderate to good in all groups (kappa = 0.76, 0.53, and 0.76). All participants found the MC helpful (22%) to very helpful (78%) for understanding the fracture and planning ORIF.

The MC with special attention to involvement of ligamentous structures, the coronoid process, and the radial head, as well as an associated structured reduction technique, is helpful for the management of complex proximal ulna fracture dislocations. Despite the high rate of secondary surgeries, the final clinical outcome may lead to good to excellent results in 90% of the cases. However, young surgeons with less experience seemed to profit more from this classification than experts.