True compression of pelvic fractures under lateral impact

Anterior Pelvic Ring Fracture Pattern Predicts Subsequent Displacement in Lateral Compression Sacral Fractures

OBJECTIVE

To determine if anterior pelvic fracture pattern in lateral compression (LC) sacral fractures correlates with subsequent displacement on examination under anesthesia (EUA) or follow-up in both nonoperative and operative cases.

DESIGN

Retrospective cohort study.

SETTING

Level 1 trauma center.

PATIENTS

Two hundred twenty-seven skeletally mature patients with traumatic LC (OTA/AO 61B1.1, 61B2.1-2, and 61B3.1-2) pelvic ring injuries treated nonoperatively, with EUA, or with pelvic fixation were included.

INTERVENTION

The study intervention included retrospective review of patients' charts and radiographs.

MAIN OUTCOME MEASUREMENT

Displacement on EUA or follow-up radiographs (both operative and nonoperative) correlated with anterior pelvic ring fracture pattern.

RESULTS

Independent of sacral fracture pattern (complete or incomplete), risk of subsequent displacement on EUA or at follow-up after both nonoperative and operative treatments correlated strongly with ipsilateral superior and inferior pubic rami fractures that were either comminuted (95.6%, P < 0.001) or oblique (100%, P < 0.001). Patients with transverse or lack of inferior pubic ramus fracture did not displace (0%, P < 0.001). Out of 21 LC injuries treated with posterior-only fixation, displacement at follow-up occurred in all 11 patients (100%) with comminuted and/or oblique superior and inferior pubic rami fractures. Nakatani zone I and II rami fractures correlated most with risk of subsequent displacement.

CONCLUSIONS

Unstable anterior fracture patterns are characterized as comminuted and/or oblique fractures of ipsilateral superior and inferior pubic rami. EUA should be strongly considered in these patients to disclose occult instability, for both complete and incomplete sacral fracture patterns. Additionally, these unstable anterior fracture patterns are poor candidates for posterior-only fixation and supplemental anterior fixation should be considered. Irrespective of sacral fracture pattern (complete or incomplete), nonoperative management is successful in patients with transverse or lack of inferior pubic ramus fractures.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Effects of Loading Conditions on the Pelvic Fracture Biomechanism and Discrimination of Forensic Injury Manners of Impact and Run-Over Using the Finite Element Pelvic Model

This study aimed to systematically simulate the responses of pelvic fracture under impact and run-over to clarify the effects of boundary and loading conditions on the pelvic fracture mechanism and provide complementary quantitative evidence for forensic practice. Based on the THUMS finite element model, we have validated the simulation performance of the model by a real postmortem human pelvis side impact experiment. A total of 54 simulations with two injury manners (impact and run-over), seven loading directions (0°, 30°, 60°, 90°, 270°, 300°, 330°), and six loading velocities (10, 20, 30, 40, 50, and 60 km/h) were conducted. Criteria of effective strain, Von-Mises stress, contact force, and self-designed normalized eccentricity were used to evaluate the biomechanism of pelvic fracture. Based on our simulation results, it’s challenging to distinguish impact from run-over only rely on certain characteristic fractures. Loads on the front and back were less likely to cause pelvic fractures. In the 30°, 60°, 300° load directions, the overall deformation caused a “diagonal” pelvic fracture. The higher is the velocity (kinetic energy), the more severe is the pelvic fracture. The contact force will predict the risk of fracture. In addition, our self-designed eccentricity will distinguish the injury manner of impact and run-over under the 90° loads. The “biomechanical fingerprints” based on logistic regression of all biomechanical variables have an AUC of 0.941 in discriminating the injury manners. Our study may provide simulation evidence and new methods for the forensic community to improve the forensic identification ability of injury manners.

The morphological mapping of lateral compression type 1 pelvic fracture and pelvic ring stability classification: a finite element analysis

Purpose

This finite element analysis assessed lateral compression (LC-1) fracture stability using machine learning for morphological mapping and classification of pelvic ring stability.

Methods

Computed tomography (CT) files of LC-1 pelvic fractures were collected. After morphological mapping and producing matrix data, we used K-means clustering in unsupervised machine learning to classify the fractures. Based on these subtypes, we manually added fracture lines in ANSYS software. Finally, we performed a finite element analysis of a normal pelvis and eight fracture subtypes based on von Mises stress and total deformation changes.

Results

A total of 218 consecutive cases were analyzed. According to the three main factors—zone of sacral injury and completion, pubic ramus injury side, and the sagittal rotation of the injured hemipelvis—the LC-1 injuries were classified into eight subtypes (I–VIII). No significant differences in stress or deformation were observed between unilateral and bilateral public ramus fractures. Subtypes VI and VIII showed the maximum stress while subtypes V–VIII showed the maximum deformation in the total pelvis and sacrum. The subtypes did not differ in superior public ramus deformation.

Conclusions

Complete fracture of sacrum zones 2/3 may be a feature of unstable LC-1 fractures. Surgeons should give surgical strategies for subtypes V–VIII.

The traditional experience strategy (TES) and combined ultrasonography examination (CUE) for the treatment of lateral compression type 1 pelvic fractures: a historical control study

BACKGROUND

It is difficult to judge the stability of lateral compression type-1 (LC-1) pelvic fracture, as it is often based on static images of the pelvis. Compared with the traditional experience strategy, ultrasonography examination may be able to distinguish operative and conservative patients before definitive treatment. However, in previous studies, we have not compared the outcomes between traditional experience strategy (TES group) and combined ultrasonography examination (CUE group). Thus, the aim of the study is comparing the differences between TES and CUE strategy, to identify the value of ultrasonography examination.

METHODS

Medical records system for patients with LC-1 pelvic fractures who were treated with TES and CUE strategy were included. Patients' baseline characteristics, treatment strategy, and function were recorded at follow-up. Functional outcomes were evaluated using the Majeed grading system.

RESULTS

In total, 77 patients with LC-1 pelvic fractures were included in the study. There were 42 and 35 patients in TES and CUE group, respectively. Compared to TES group (69 %), there were less proportion patients chosen the operative treatment in CUE group (43 %, P = 0.021). The volume of intraoperative blood loss in CUE operative group was more than TES operative group (P = 0.037). There were more patients with complete sacral fracture in CUE operative group than TES operative group (P = 0.002). The Majeed scores in CUE conservative group was higher than TES conservative group (P = 0.008). The overall Majeed scores in CUE group was higher than that in TES group (P = 0.039).

CONCLUSIONS

The ultrasonography examination could relatively accurately identify the unstable LC-1 pelvis than the traditional experience strategy, the operative rate could be reduced and the overall function of LC-1 patients could be improved under the ultrasonography examination.

LEVEL OF EVIDENCE

Level III.

The Lateral Stress Radiograph Identifies Occult Instability of Lateral Compression Pelvic Ring Injuries Without Sedation

OBJECTIVES

To determine if pelvic ring displacement on the lateral stress radiograph (LSR) correlated with displacement on examination under anesthesia (EUA).

DESIGN

Retrospective cohort study.

SETTING

Urban Level I trauma center.

PATIENTS/PARTICIPANTS

Twenty consecutive patients with unilateral minimally displaced LC1 injuries with complete sacral fractures.

INTERVENTION

An anteroposterior pelvis radiograph taken in the lateral decubitus position (LSR) was performed on awake patients before EUA in the operating room.

MAIN OUTCOME MEASUREMENTS

Correlation between ≥1 cm of pelvic ring displacement on the LSR and EUA.

RESULTS

The LSR demonstrated ≥1 cm of displacement in 11 of the 20 patients (55%). All of these patients had ≥1 cm of displacement on EUA and underwent surgical fixation. The remaining 9 patients with <1 cm of displacement on the LSR also had <1 cm of displacement on EUA and were managed nonoperatively.

CONCLUSIONS

The LSR reliably identified occult instability in LC1 pelvic ring injuries and demonstrated 100% correlation with EUA. In contrast to EUA, the LSR does not require sedation and normalizes the amount of force applied to determine instability.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Feasibility of anterior pelvic ring fixation alone for treating lateral compression type 1 pelvic fractures with nondisplaced complete sacral fractures: a retrospective study

Purpose

The aim of this study was to evaluate the feasibility of anterior pelvic ring fixation alone for treating lateral compression type 1 (LC-1) fractures with nondisplaced complete sacral fractures.

Methods

Patients with LC-1 type pelvic fractures with nondisplaced complete sacral fractures in the Xi’an Honghui Hospital were screened. Those who underwent surgical treatment for the anterior pelvic ring fractures and conservative treatment for the sacral factures were included in the analysis. The Majeed and Short Form-12 (SF-12) functional scores were used to evaluate these patients.

Results

Of the 123 patients enrolled, 108 (88%) responded to our enquiries regarding the outcome. The mean follow-up period was 18.37 months for the 108 patients who responded. The mean SF-12 functional score was 48.22 ± 9.68. The mean Majeed score was 83.47 ± 9.23, including 52 with excellent, 47 with good, seven with fair, two with poor outcomes. The SF-12 functional and Majeed scores were significantly higher in those aged <45 years or without lower limb injury than in those aged ≥45 years or with lower limb injury (P < 0.05).

Conclusion

Acceptable functional outcomes can be obtained for LC-1 pelvic fractures with nondisplaced complete sacral fractures by using anterior pelvic ring fixation alone.