A predictive scoring system for late displacement and deformity following non-operative treatment of Young-Burgess lateral compression type 1 (OTA 61-B1/B2) pelvic ring injuries.

Objective: To identify risk factors and develop a scoring system based on static x-rays that can predict late displacement and deformity of non-operatively treated Young-Burgess lateral compression type 1 (LC1) pelvic ring injuries METHODS: A retrospective review of all non-operatively treated low-energy LC1 (AO/OTA 61-B2/B3) pelvic ring injuries in patients aged ≥50 associated with incomplete zone 1 sacral fractures and minimum three-month follow-up between January 2019 through January 2024 from two academic level 1 trauma centers. Exclusion criteria were non-acute presentations, nonunions, pathological fractures and non-ambulatory patients. Anterior-posterior, inlet and outlet radiographic imaging at initial, post-operative and final follow-up were assessed.The primary outcome measure was greater than 1 cm of pelvic ring displacement from initial to final radiographs showing fracture healing. Patient demographic and radiographic factors were described with univariate analyses. Statistically significant variables (P < 0.05) entered a multivariable logarithmic regression to develop a scoring system through stepwise elimination, which was assessed via receiver operator characteristic (ROC) curve analysis.

Results: A total of 197 LC1 injuries in patients managed non-operatively (mean age 75.6 (50-103) years, n= 147 (74.6 %) female) were included for analyses. Variables correlated with pelvic deformity development on univariate analysis included, increasing age (p = 0.038), whether the anterior ring had initial displacement present (p < 0.001), bilateral anterior ring involvement (p = 0.027), unstable superior ramus fracture angle (p < 0.001), superior ramus comminution (p < 0.001), Nakatani zone 1 of ipsilateral fracture (p < 0.001), and Nakatani zone 1 of contralateral fracture (if bilateral) (p = 0.031). After multivariate analysis with stepwise elimination, only superior ramus fracture angle (oblique OR 4.88, 95 % CI 2.09-12.25; longitudinal OR 15.55, 95 % CI 4.81-56.42), anterior ring initial displacement present (OR 5.05, 95 % CI 1.93-14.29) and superior ramus comminution (OR 4.43 95 % CI 1.99-10.15) remained significant as variables correlating with the development of pelvic deformity (all p ≤ 0.001).

Conclusions: The statistically significant variables that correlated with late displacement and deformity of LC1 fracture patterns were superior ramus fracture angle, comminution, and initial anterior ring displacement. A combination of these factors increased the risk of displacement.