Finite element analysis of five internal fixation modes in treatment of Day type Ⅱcrescent fracture dislocation of pelvis / 中国修复重建外科杂志

OBJECTIVE@#To compare the biomechanical differences among the five internal fixation modes in treatment of Day type Ⅱ crescent fracture dislocation of pelvis (CFDP), and find an internal fixation mode which was the most consistent with mechanical principles.@*METHODS@#Based on the pelvic CT data of a healthy adult male volunteer, a Day type Ⅱ CFDP finite element model was established by using Mimics 17.0, ANSYS 12.0-ICEM, Abaqus 2020, and SolidWorks 2012 softwares. After verifying the validity of the finite element model by comparing the anatomical parameters with the three-dimensional reconstruction model and the mechanical validity verification, the fracture and dislocated joint of models were fixed with S 1 sacroiliac screw combined with 1 LC-Ⅱ screw (S 1+LC-Ⅱ group), S 1 sacroiliac screw combined with 2 LC-Ⅱ screws (S 1+2LC-Ⅱ group), S 1 sacroiliac screw combined with 2 posterior iliac screws (S 1+2PIS group), S 1 and S 2 sacroiliac screws combined with 1 LC-Ⅱ screw (S 1+S 2+LC-Ⅱ group), S 2-alar-iliac (S 2AI) screw combined with 1 LC-Ⅱ screw (S 2AI+LC-Ⅱ group), respectively. After each internal fixation model was loaded with a force of 600 N in the standing position, the maximum displacement of the crescent fracture fragments, the maximum stress of the internal fixation (the maximum stress of the screw at the ilium fracture and the maximum stress of the screw at the sacroiliac joint), sacroiliac joint displacement, and bone stress distribution around internal fixation were observed in 5 groups.@*RESULTS@#The finite element model in this study has been verified to be effective. After loading 600 N stress, there was a certain displacement of the crescent fracture of pelvis in each internal fixation model, among which the S 1+LC-Ⅱ group was the largest, the S 1+2LC-Ⅱ group and the S 1+2PIS group were the smallest. The maximum stress of the internal fixation mainly concentrated at the sacroiliac joint and the fracture line of crescent fracture. The maximum stress of the screw at the sacroiliac joint was the largest in the S 1+LC-Ⅱ group and the smallest in the S 2AI+LC-Ⅱ group. The maximum stress of the screw at the ilium fracture was the largest in the S 1+2PIS group and the smallest in the S 1+2LC-Ⅱ group. The displacement of the sacroiliac joint was the largest in the S 1+LC-Ⅱ group and the smallest in the S 1+S 2+LC-Ⅱ group. In each internal fixation model, the maximum stress around the sacroiliac screws concentrated on the contact surface between the screw and the cortical bone, the maximum stress around the screws at the iliac bone concentrated on the cancellous bone of the fracture line, and the maximum stress around the S 2AI screw concentrated on the cancellous bone on the iliac side. The maximum bone stress around the screws at the sacroiliac joint was the largest in the S 1+LC-Ⅱ group and the smallest in the S 2AI+LC-Ⅱ group. The maximum bone stress around the screws at the ilium was the largest in the S 1+2PIS group and the smallest in the S 1+LC-Ⅱ group.@*CONCLUSION@#For the treatment of Day type Ⅱ CFDP, it is recommended to choose S 1 sacroiliac screw combined with 1 LC-Ⅱ screw for internal fixation, which can achieve a firm fixation effect without increasing the number of screws.

Treatment of Day type Ⅱ pelvic crescent fracture by using percutaneous cannulated screw fixation technique / 中国修复重建外科杂志

Results: The operation time was 35-95 minutes (mean, 55 minutes), cumulative C-arm fluoroscopy time was 3-8 minutes (mean, 5 minutes), no iatrogenic vascular injury and pelvic organ damage occurred. Postoperative X-ray films at 2 days indicated that 2 cases of vertical shift and 2 cases of mild rotation were not completely corrected. Postoperative CT examination at 3 days indicated that 2 pubic joint screws broke through the obturator bone cortex. None of the pubic ramus screws entered into the acetabulum, but a screw of superior pubic branch broke through the posterior cortical of superior pubic branch, a screw of posterior ilium column broke through the medial bone cortex of the ilium, and no clinical symptom was observed. One patient suffered from wound infection in the pubic symphysis, then healed after 2 weeks of wound drainage, the other wounds healed by first intention. According to Matta criterion for fracture reduction, the results were excellent in 9 cases, good in 4 cases, and fair in 1 case with an excellent and good rate of 92.9%. All patients were followed up 8-24 months (mean, 14 months). All fractures healed at 4 months and restored to the normal walking at 6 months after operation, 3 patients suffered from slight pain in the sacroiliac joints and slight claudication when they were tired or walked for a long time and unnecessary for special treatment. One patient felt pain in the back of the iliac spine when he was lying down. During the follow-up, no screw loosening or other internal fixation failure occurred. At last follow-up, according to Majeed functional evaluation criteria, the results were excellent in 7 cases, good in 5 cases, and fair in 2 cases with an excellent and good rate of 85.7%.

Atypical Pelvic Crescent Fracture Caused by Vertical Shear Force / 대한고관절학회지

The crescent fracture consists of a posterior iliac wing fracture with extension into the sacroiliac joint and a dislocation of the sacroiliac joint. This fracture represents a subset of lateral compression injury. The strong posterior ligaments of sacroiliac joint remain intact and a fracture fragment (crescent shape) involving the posterior superior iliac spines remains firmly attached to the sacrum. We report a patient with atypical pelvic crescent fracture that is mainly influenced by vertical shear injury and is characterized by posterior fracture-dislocations of the sacroiliac joint. In this case report, we review the literature on classification and treatment of atypical type of crescent fracture.

Intrapelvic Anterior Plate Fixation for Crescent Fracture-Dislocation of Sacroiliac Joint

PURPOSE: To evaluate the radiological and clinical outcomes of intrapelvic anterior plate fixations for Day Classification Type II crescent fracture-dislocations of sacroiliac joints. MATERIALS AND METHODS: Ten patients who had undertaken the surgical treatment for the sacroiliac joint from 2006 to 2012 were enrolled in this study. All cases fell into Type II by Day Classification for sacroiliac joint injuries. For surgical treatments, the plate fixation through the intra-pelvic anterior approach was first performed for all cases and anterior ring fixation was performed in 4 cases with more severely displaced anterior pelvic ring injuries. Then, radiological and clinical evaluation was implemented. RESULTS: The bone union was observed from all patients whom performed the surgical fixation. In the radiological results, 9 cases with the anatomic and nearly-anatomic reductions were observed. Out of the 10 cases which performed the rotational displacement analysis, there were 3 excellent cases, 6 good cases and 1 fair case. The 10 cases that performed the deformity index and vertical displacement analysis, less variations were observed in the anterior ring fixations after intra-pelvic anterior plate fixation group. According to the clinical results, 4 excellent cases, 3 good cases, and 3 moderate cases were observed. CONCLUSION: In the Type II crescent fracture-dislocation of sacroiliac joint, the intrapelvic anterior plate fixation achieved satisfactory anatomical reductions, radiological stabilities and clinical results.

Crescent Fracture-dislocation of Sacroiliac Joint: Affecting Factors of Operative Results

PURPOSE: To assess the affecting factors of results after the operation of Crescent fracture-dislocation in sacro-iliac joint. MATERIALS AND METHODS: In 19 patients (mean age, 47.4 year-old) of open reduction and internal fixation for Crescent fracture-dislocation, there were seven type I, 9 type II, and 3 type III fractures according to Day's classification. We assessed affecting factors of radiological and functional results, such as patients' ages, surgical approaches, the fixation extent of pelvic ring, and fracture patterns. RESULTS: Seventeen of 19 cases united at 14.5 weeks in average, and 2 non-unions occurred with the fixation failure of posterior ring. Satisfactory results were 14 and 15 in radiological and functional evaluation, respectively. In complications, three cases of leg length discrepancy were from an imperfect reduction and two fixation failures. Surgical approach did not show any difference of results, but all cases of unsatisfactory reduction occurred from posterior ring fixation through the anterior approach. Fixation of both rings seemed to have satisfactory results, comparing to posterior ring only. Older patients over 60 year-old had more complications and a tendency to show an unsatisfactory result. CONCLUSION: In operative treatment of Crescent fracture-dislocation of sacro-iliac joint, it is better to fix both anterior and posterior rings. But, caution is needed to prevent complications in old-aged patients.