ABSTRACT
Finite element method (FEM) was used to investigate the biomechanical properties of three types of surgical fixations of U-shaped sacral fractures. Based on a previously established and validated complete lumbar-pelvic model, three models of surgical fixations of U-shaped sacral fractures were established: ① S1S2 passed through screw (S1S2), ② L4-L5 pedicle screw + screw for wing of ilium (L4L5 + IS), and ③ L4-L5 pedicle screw + S1 passed through screw + screw for wing of ilium (L4L5 + S1 + IS). A 400 N force acting vertically downward, along with torque of 7.5 N·m in different directions (anterior flexion, posterior extension, axial rotation, and axial lateral bending), was exerted on the upper surface of L4. Comparisons were made on differences in separation of the fracture gap and maximum stress in sitting and standing positions among three fixation methods. This study showed that: for values of separation of the fracture gap produced by different operation groups in different positions, L4L5 + S1 + IS was far less than L4L5 + IS and S1S2. For internal fixators, the maximum stress value produced was: L4L5 + IS > L4L5 + S1 + IS > S1S2. For the intervertebral disc, the maximum stress value produced by S1S2 is much larger than that of L4L5 + S1 + IS and L4L5 + IS. In a comprehensive consideration, L4L5 + S1 + IS could be prioritized for fixation of U-shaped sacral fractures. The objective of this research is to compare the biomechanical differences of three different internal fixation methods for U-shaped sacral fractures, for the reference of clinical operation.
Subject(s)
Humans , Biomechanical Phenomena , Finite Element Analysis , Fracture Fixation , Methods , Lumbar Vertebrae , Pedicle Screws , Sacrum , Wounds and Injuries , Spinal Fractures , General Surgery , Spinal FusionABSTRACT
U-shaped sacral fractures are rare and often difficult to diagnose primarily due to the difficulty in obtaining adequate imaging and the severe associated injuries.These fractures are highly unstable and frequently cause neurological deficits.The majority of surgeons have limited experience in management of U-shaped sacral fractures.No standard treatment protocol for U-shaped sacral fractures has been available till now.This study aimed to examine the management of U-shaped sacral fractures and the early outcomes.Clinical data of 15 consecutive patients with U-shaped sacral fracture who were admitted to our trauma center between 2009 and 2014 were retrospectively analyzed.Demographics,fracture classification,mechanism of injury and operative treatment and deformity angle were assessed.All the patients were treated with lumbopelvic fixation or (and) sacral decompression.EQ-5d score was applied to evaluate the patients' quality of life.Of the 15 consecutive patients with U-shaped sacral fracture,the mean age was 28.8 years (range:15-55 years) at the time of injury.There were 6 females and 9 males.The mean followup time was 22.7 months (range:9-47 months) and mean full weight-bearing time was 9.9 weeks (range:8-14 weeks).Ten patients received lumbopelvic fixation and sacral decompression,one lombosacral fixation,and 4 merely sacral decompression due to delayed diagnosis or surgery.The post-operation deformity angle (mean 27.87°,and range:8°-90°) of the sacrum was smaller than that pre-operation (mean 35.67;range:15-90) with no significance difference noted.At the latest follow-up,all patients obtained neurological recovery with different extents.Visual analogue score (VAS) was reduced from preoperative 7.07 (range:5-9) to postoperetive 1.93 (range:1-3).All patients could walk without any aid after treatment.Eight patients were able to care for themselves and undertook some daily activities.Five patients had returned to work full time.In conclusion,lumbopelvic fixation is an effective method for stabilization of U-shaped sacral fractures with fewer complications developed.Effective reduction and firm fixation are the prerequisite of early mobilization and neurological recovery.Sacral decompression effectively promotes neurological recovery even in patients with old U-shaped sacral fractures.
ABSTRACT
U-shaped sacral fractures are rare and often difficult to diagnose primarily due to the difficulty in obtaining adequate imaging and the severe associated injuries.These fractures are highly unstable and frequently cause neurological deficits.The majority of surgeons have limited experience in management of U-shaped sacral fractures.No standard treatment protocol for U-shaped sacral fractures has been available till now.This study aimed to examine the management of U-shaped sacral fractures and the early outcomes.Clinical data of 15 consecutive patients with U-shaped sacral fracture who were admitted to our trauma center between 2009 and 2014 were retrospectively analyzed.Demographics,fracture classification,mechanism of injury and operative treatment and deformity angle were assessed.All the patients were treated with lumbopelvic fixation or (and) sacral decompression.EQ-5d score was applied to evaluate the patients' quality of life.Of the 15 consecutive patients with U-shaped sacral fracture,the mean age was 28.8 years (range:15-55 years) at the time of injury.There were 6 females and 9 males.The mean followup time was 22.7 months (range:9-47 months) and mean full weight-bearing time was 9.9 weeks (range:8-14 weeks).Ten patients received lumbopelvic fixation and sacral decompression,one lombosacral fixation,and 4 merely sacral decompression due to delayed diagnosis or surgery.The post-operation deformity angle (mean 27.87°,and range:8°-90°) of the sacrum was smaller than that pre-operation (mean 35.67;range:15-90) with no significance difference noted.At the latest follow-up,all patients obtained neurological recovery with different extents.Visual analogue score (VAS) was reduced from preoperative 7.07 (range:5-9) to postoperetive 1.93 (range:1-3).All patients could walk without any aid after treatment.Eight patients were able to care for themselves and undertook some daily activities.Five patients had returned to work full time.In conclusion,lumbopelvic fixation is an effective method for stabilization of U-shaped sacral fractures with fewer complications developed.Effective reduction and firm fixation are the prerequisite of early mobilization and neurological recovery.Sacral decompression effectively promotes neurological recovery even in patients with old U-shaped sacral fractures.
ABSTRACT
Objective To study the mechanism of sacral plexus injury resulting from anteroposteri- or compression zone-Ⅱsacral fractures.Methods Six short-term(within one year)embalmed pelves were obtained from Anatomic Department of Hebei Medical University.The preserved sacral plexus and re- sected pubic symphysis were used to make the models of anteropesterior compression zone-Ⅱsacral frac- tures.Quantitative analysis for fracture displacement was carried out to observe the characteristics and mechanism of sacral plexus injury.The removed sacral plexus was replaced by proportional diameter silica gel pips filled with contrast medium.The experimental procedure was repeated under X-ray.The experi- mental data were analyzed by SPSS 10.0 statistic software to obtain result.Results In anteropostefior compression sacral fracture,sacral nerve canal was gradually opened and its volume raised.No sacral nerve was opressed in nerve canal.However ilium external rotation prolonged sacral nerves,especially S_1,S_4 and the more the pubic symphsis was separated the more the sacral plexus nerves were prolonged.At the same time,the sharp border of fracture segment stabbed the nerves,especially L_5(6 cases),S_1(5 cases)and S_2 (3 eases).Conclsions Sacral plexus is tightly connected with the wall of pelvic cavity and fixed. When zone-Ⅱsacral fractures happen sacral plexus is easily damaged.In anteroposterior compression sacral fracture,nerves S_1 and S_4 are likely to be damaged by dragment,and nerve compression injury is attributed to stabbing by fracture segment border,with L_5 and S_1.more hackneyed.