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Objective To discuss the 3D printing modeling used to assist minimally invasive fixation with hollow screws for unstable pelvic fractures.Methods From January 2014 to January 2016,137 patients with unstable pelvic fracture received minimally invasive fixation with hollow screws and obtained complete follow-up at our department.In 65 of them,the fixation was assisted by 3D printing modeling;they were 37 men and 28 women,with an average age of 33.1 ± 4.9 years.In the other 72 cases,conventional fixation was performed without assistance of 3D printing modeling;they were 45 men and 27 women,with an average age of 32.6 ±4.7 years.The 2 groups were compared in terms of operation time,frequency of intraoperative fluoroscopy,reduction quality and curative effect.Results This cohort were followed up for 6 to 15 months (average,9 months).The 3D printing modeling group needed significantly less operation time (58.6 ± 13.4 min) and intraoperative fluoroscopy (29.3 ± 3.6 frequencies) than the conventional group (72.4 ± 12.4 min and 36.6 ± 2.8 frequencies) (P ＜ 0.05).According to the Matta scoring criteria,the quality of pelvic reduction was evaluated as excellent in 21 cases,as good in 30 cases,as fair in 13 cases and as poor in one in the 3D printing group,yielding an excellent and good rate of 78.5％ while as excellent in 22 cases,as good in 36 cases,as fair in 12 cases and as poor in 2 cases in the conventional group,yielding an excellent and good rate of 80.6％.According to the Majeed scoring criteria,the curative effect was evaluated at the last follow-up as excellent in 27 cases,as good in 26 cases,as fair in 11 cases and poor in one in the 3D printing group,giving an excellent and good rate of 81.5％ while as excellent in 30 cases,as good in 28 cases,as fair in 13 cases and as poor in one in the conventional group,giving an excellent and good rate of 80.6％.There were no statistically significant differences between the 2 groups in reduction quality or curative effect (P ＞ 0.05).No nonunion or iatrogenic neurovascular lesions happened during the follow-up period.Conclusion 3D-printing modeling is helpful for a good reduction and minimally invasive fixation with hollow screws for unstable pelvic fractures by reducing operation time and intraoperative fluoroscopy.
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Objective To compare the biomechanical properties of non-locking compression plate (DCP) and locking compression plate (LCP) in the internal fixation of humeral shaft fracture by means of finite element analysis.Methods Three-dimensional finite element models were constructed to simulate DCP and LCP internal fixation of humeral transverse fracture.The DCP and LCP groups were compared in terms of peak stress on the humeral fracture fragments (MPa),peak stress on the screws (MPa),and overall displacement peak value (mm) under 4 basic loads (bending,shear,torsion and compression).The biomechanical stability was analyzed after fracture fixation.Results The stress tended to concentrate at the connection sites of plate and screws and distributed evenly on DCP.The stress distributed in a gradient manner at the multiple screw holes and tended to concentrated on the central screws on LCP.Under the bending,shear and torsion loadings,the peak stresses on the fracture fragments and screws in the DCP fixation were larger than in the LCP fixation.However,under the compression loading,the peak stresses on the fracture fragments and screws in the DCP fixation were smaller than in the LCP fixation.DCP and LCP had similar trends in displacement.Under the bending,shear and torsion loadings,the overall displacement peak values in LCP fixation were smaller.However,under the compression loading,the overall displacement peak values in DCP fixation were smaller.Conclusions DCP and LCP have similar biomechanical properties to resist bending,shear,torsion and compression.Due to the gradient distribution of stress among the screw holes,LCP is more suitable for patients with comminuted fracture or osteoporosis.Stress distribution is more even in DCP.Surgeons should consider the advantages of both DCP and LCP to achieve better stability.
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Objective To explore the treatment and clinical outcomes of unstable combined fractures of pelvis and acetabulum.Methods From January 2013 through December 2014,21 unstable pelvic fractures associated with acetabular fractures received surgical treatment at our department.They were 18 men and 3 women,aged from 21 to 55 years (average,43.2 years).By the Tile classification for pelvic fractures,12 cases were type B and 9 type C.By the Letourel-Judet classification for acetabular fractures,11 cases were transverse fractures,5 both-column fractures,3 posterior column + posterior wall fractures,and 2 anterior column fractures.The intervals between injury and surgery averaged 6.5 days (from 4 to 15 days).Results The 21 cases were followed up for 6 to 18 months (average,9 months).According to the Matta's criteria for pelvic reduction,5 cases were excellent,12 good,and 4 fair,giving an excellent to good rate of 81.0％.According to the Matta's criteria for acetabular reduction,5 cases were excellent,11 good,and 5 poor,giving an excellent to good rate of 76.2％.The pelvic fractures healed after 12 to 18 weeks (average,14.5 weeks);the acetabular fractures healed after 12 to 22 weeks (average,15.5 weeks).According to the Majeed's functional evaluation at the last follow-ups,10 cases were excellent,8 good and 3 fair,giving an excellent to good rate of 85.7％.According to the Merle d'Aubigné-postel evaluation,8 cases were excellent,9 good,and 4 fair,giving an excellent to good rate of 81.0％.Three patients had nerve injury which was almost completely recovered 4 to 6 months after operation.Two cases had wound infection which was controlled after debridement for twice.No other complications like ectopic ossification,avascular necrosis of the femoral head,iatrogenic vascular or nerve lesion was observed during the follow-ups.Conclusion Precise diagnosis,rational plan,careful surgery,effective reduction,rigid fixation and active rehabilitation are keys to fine outcomes in the treatment of unstable pelvic fractures associated with acetabular fractures.
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Objective To investigate the methods of X-ray diagnosis of various displacement of unstable pelvic fracture in three-dimensional space and its instructive significance in closed reduction.Methods A normal adult pelvic specimen was selected and fixed in a wood-frame at supine position after soft tissue rejection and ligament preservation.With the breakage at the unilateral anterior-posterior ring,models of hemipelvic rotation in the transverse and sagittal planes and hemipelvic vertically upward displacement were induced.Anteroposterior radiographs of the pelvic specimen were made and picture archiving and communication system (PACS) was used to measure width of iliac wing,suprainferior diameter of hemipelvis,vertical displacement of iliac crest,acetabulum roof,pubic tubercle and sciatic tuber and area of obturator foramen.Methods of X-ray diagnosis of various displacements of hemipelvis were concluded and applied in treatment of 43 patients with unstable pelvic fractures.Operation time and intraoperative blood loss were recorded.Postoperative images were evaluated by Matta standard.Results Hemipelvic rotation in transverse plane included eversion and inversion.Width of iliac crest was enlarged and area of obturator foramen was shrunk while extroversion ; on the contrary,an opposite result was observed while inversion.Sagittal rotation included pronation and supination.Pubic tubercle had obvious downward shift,iliac crest presented no change or slight upward shift,suprainferior diameter of hemipelvis was lengthened,iliac roof and sciatic tuber remained their position unchanged and area of obturator foramen was shrunk while pronation; on the contrary,pubic tubercle had obvious upward shift,iliac crest presented no change or slight downward shift,suprainferior diameter of hemipelvis was shortened,iliac roof and sciatic tuber remained their position unchanged and area of obturator foramen was enlarged while supination; iliac crest,acetabular roof,pubic tubercle and sciatic tuber presented equidistant upward shift while the hemipelvis displaced upward vertically.Average operation time was 55 minutes (range,15-85 minutes) and intraoperative blood loss was 26 ml (range,10-50 ml).According to Matta standard,pelvic radiography evaluation at postoperative 3 days was excellent in 31 cases and good in 12 cases,with excellent and good rate of 100％.Conclusion Pelvis X-ray films are able to diagnose various three-dimensional displacement of unstable pelvic fractures and guide closed reduction timely and rapidly to achieve satisfactory result.