Biomechanical tests and finite element analyses of pelvic stability using bilateral single iliac screws with different channels in lumbo-iliac fixation.

Background: In lumbo-iliac fixation, the iliac screw can be placed in several locations and directions. There is no uniform standard for the placement of a single iliac screw. Biomechanical tests and finite element analyses were used to compare the effect of bilateral single iliac screws with three channels on pelvic stability to determine the best channel. Methods: Five embalmed adult cadaver pelvic specimens were selected. An unstable Tile C1 pelvic injury model was established. Lumbo-iliac fixation for the treatment of left sacral Denis II fracture includes the following: three channels of bilateral, single iliac screws (channel A from posterior superior iliac spine (PSIS) to anterior inferior iliac spine (AIIS), channel B from 1 cm medial and 1 cm caudal of PSIS to AIIS, and channel C from 2 cm below PSIS to AIIS). Biomechanical testing was performed for stiffness evaluations. A finite element model was established to study the stress distribution of the model and the maximum von Mises stress of internal fixation. Results: Biomechanical tests revealed that under vertical compression loading. The compressive stiffness fixed by channel B (246.15 ± 27.85 N/mm) was better than that fixed by channel A and channel C. Under torsional load, the torsional stiffness fixed by channel B (2.234 ± 0.223 N·m/°) was stronger than that fixed by channel A and channel C. However, there was no significant difference in terms of compressive and torsional stiffness between channel B and channel A (P > 0.05). Finite element analyses conformed that the maximum von Mises stress of the internal fixator fixed in channel B under the conditions of vertical, forwards bending, backwards extension, left bending, left rotating, and right bending (213.98 MPa, 338.96 MPa, 100.63 MPa, 297.06 MPa, 200.95 MPa and 284.75 MPa, respectively) was significantly lower than those fixed in channel A and channel C. Conclusions: The construct stiffness of the channel from 1 cm medial and 1 cm caudal of PSIS to AIIS is better than that of the other two channels. This channel has the advantages of good biomechanical stability, small maximum von Mises stress of internal fixation.

[One-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion for the treatment of lumbosacral tuberculosis].

OBJECTIVE: To investigate the clinical effect of One-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion for the treatment of lumbosacral tuberculosis. METHODS: The clinical data of 31 patients with lumbosacral tuberculosis treated by one-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion from January 2013 to February 2018 were retrospectively analyzed. There were 18 males and 13 females, aged from 18 to 77 years old with an average of (45.9±9.1) years. The lesion segment was form L4 to S2. The preoperative ASIA grading showed that 2 cases were grade B, 17 cases were grade C, 12 were grade D. Pre- and post-operative C reactive protein (CRP), visual analogue scale (VAS), erythrocyte sedimentation rate (ESR), ASIA grade, lumbosacral angle and intervertebral space height were analyzed, the surgery complications, stability of internal fixation, bone fusion were observed. RESULTS: All the 31 patients were followed up for 10 to 24 months with an average of (16.0±3.1) months. One patient with local infection and subcutaneous hydrops was cured by dressing change. Other 30 cases got primary healing without sinus formation and no recurrence of spinal tuberculosis. All the patients were cured, no internal fixation loosening and breakage were found. All bone fusion was successful with an average fusion time of (4.7±1.1) months. At the final follow-up, ESR and CRP were normal, the VAS was decreased from (6.13±1.21) points preoperatively to (1.92±0.57) pioints, the ASIA grading showed that 2 cases were grade C, 6 cases were grade D, and 23 cases were grade E. The lumbosacral angle and intervertebral space height was increased from preoperative (21.42±3.75) °, (7.84±0.41) mm to (27.21±3.12) °, (9.80±0.38) mm at the final follow-up, respectively. CONCLUSION: One-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion is a practicable, effective and safe method for the treatment of lumbosacral tuberculosis. It can be recommended in clinical application.

One-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion for the treatment of lumbosacral tuberculosis / 中国骨伤

OBJECTIVE@#To investigate the clinical effect of One-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion for the treatment of lumbosacral tuberculosis.@*METHODS@#The clinical data of 31 patients with lumbosacral tuberculosis treated by one-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion from January 2013 to February 2018 were retrospectively analyzed. There were 18 males and 13 females, aged from 18 to 77 years old with an average of (45.9±9.1) years. The lesion segment was form L to S. The preoperative ASIA grading showed that 2 cases were grade B, 17 cases were grade C, 12 were grade D. Pre- and post-operative C reactive protein (CRP), visual analogue scale (VAS), erythrocyte sedimentation rate (ESR), ASIA grade, lumbosacral angle and intervertebral space height were analyzed, the surgery complications, stability of internal fixation, bone fusion were observed.@*RESULTS@#All the 31 patients were followed up for 10 to 24 months with an average of (16.0±3.1) months. One patient with local infection and subcutaneous hydrops was cured by dressing change. Other 30 cases got primary healing without sinus formation and no recurrence of spinal tuberculosis. All the patients were cured, no internal fixation loosening and breakage were found. All bone fusion was successful with an average fusion time of (4.7±1.1) months. At the final follow-up, ESR and CRP were normal, the VAS was decreased from (6.13±1.21) points preoperatively to (1.92±0.57) pioints, the ASIA grading showed that 2 cases were grade C, 6 cases were grade D, and 23 cases were grade E. The lumbosacral angle and intervertebral space height was increased from preoperative (21.42±3.75) °, (7.84±0.41) mm to (27.21±3.12) °, (9.80±0.38) mm at the final follow-up, respectively.@*CONCLUSION@#One-stage posterior debridement combined with lumbar-ilium fixation and bone graft fusion is a practicable, effective and safe method for the treatment of lumbosacral tuberculosis. It can be recommended in clinical application.

Application of lumbo-iliac fixation in pelvic ring reconstruction following communited Denis Ⅲ sacral fractures / 中华创伤杂志

Objective To study the anatomic morphology of posterior column of ilium(PCI)and valne of lumbo-iliac fixation(LIF)in pelvic ring reconstruction following communited Denis Ⅲ sacral fractures.Methods A total of 17 hemi-sectional pelvis and dry ilia were selected to observe the length,width and height(safety and standard)of PCI,when a detailed description was done on the methods determining entry point and operation techniqus for iliac screws anchoring.Nine patients with eommunited sacral fractures involving Denis Ⅲ areas combined with neurologic deficits were decompressed for recovery of neurological function and reconstruction of pelvic ring by using LIF.Postoperative follow-up was done on role of LIF and result of neural rehabilitation.Results PCI was mean 110.57 mm in length,24.24 mm in width,14.54 mm in standard height and 31.46 mm in safe height.Nine patients could turn over in bed immediately following operation and walk one month later.A follow-up for 13-37 months in eight patients showed stable reconstructed pelvic ring,sound function of movement and bone graft fusion,which met the target of keeping stability of fractured extremity and pelvis.Conclusions pCI can provide anatomic support for LIF.When decompression and fixation is needed for sacral fractures combined with anterior pelvic ring disruptions,LIP can provide stable fixation and play an important role in reconstruction,nursing and rehabilitation of pelvic ring.