The Study To Prevent Nonunion And Femoral Neck Necrosis Of The Femoral Neck Fracture With Early Intervention

Femoral neck fracture is a common fracture in clinical,80%of whichwere displaced fractures. With the development of surgical techniques andimprovement of internal fixation material, we have some progress in thetreatment of femoral neck fracture, but the fracture healing rate and femoralhead necrosis rate is still high, which were about10%and30%respectively.On the other hand, although hip arthroplasty provides another treatmentoption for femoral neck fracture, the choice of internal fixation, total hipreplacement and hemiarthroplasty is lack of a quantitative program. Thechoice of surgical method was affected by the subjective factors to a largeextent, so the femoral neck fractures are "unsolved fracture".We uesd the method of iliac bars95°angle implantation combined withthree cannulated screws for early intervention of patients with femoral neckfracture, achieved good results. The iliac bars itself is irregular in shape whichcould make intraoperative implantation difficult,and usually associated withpain and other complications of the donor site. Therefore, we and Institute ofMetal Research (Chinese Academy of Sciences) are going to developbiodegradable magnesium stent as alternative material to autogenous bonegraft,which can promote bone formation while degradating. In order toachieve the standardization of surgical treatment of femoral neck fracture,wedesigned the first quantitative score table for patients over18years old,andconducted retrospective studies and prospective studies using it.Part1Biomechanical study of femoral neck fracture fixed with threecannulated screws and magnesium stentObjective:To compare the biomechanical effects between the iliac bars95°angle implantation combined with three cannulated screws andmagnesium stent95°angle implantation supplemented with three cannulated screws.Methods:Ten pairs of adult male cadavers were selected with an average64-year-old (60-72years). The BMD of proximal femur of all specimens wasmeasured with an osteocore dual-energy X-ray bone density instrument. Thefemur and the ipsilateral anterior superior iliac spine was removed from eachspecimen and randomly divided into experimental and control groups afterstripping of the attached soft tissue. The middle part of femoral neck wasamputated vertically using swing saw to create a fracture model. When thefracture got anatomical reduction, the iliac bars and magnesium stent wasimplanted from greater trochanter to the inferior and anterior direction offemoral head respectively,with95°angle to the horizontal plane and passedacross the fracture line about1.5cm. All specimens were conducted torsion,the vertical compression, cycle and the maximum vertical load test.In torsiontest, the femoral head was rotated clockwise to5°at a rate of0.5°/s after gotvertical load stress to10N, the torque of3°and5°were recorded. In verticalcompression experiments,the stress of femoral head gradually increased to1000N with the speed of20N/S vertically down, the displacement of700Nand1000N were recorded.then each specimen was given a load of700Nsinusoidally at0.5Hz frequency for1000cycles. Finally, the femoral head wasgiven vertical load of20N/s till the failure of internal fixation,the load atthat time was recorded. SPSS statistical software (Version13.0) was used fordata analysis.Probability values less than0.05were considered significant.Results:The BMD of the left proximal femur (0.865±0.148g/cm2) wasless than that of the right proximal femur (0.890±0.144g/cm2), but there wasno statistically significant (p>0.05). Before the cycle test,the torque of3°inthe experimental group (11.340±1.418Nm) was more than that of controlgroup (9.432±1.437Nm), the torque of5°in the experimental group (14.928the±1.402Nm) was more than that of control group (14.001±1.274Nm), andthe difference between two groups were statistically significant (p <0.05). Invertical compression experiments, the displacement of700N in theexperimental group (0.324±0.020mm) was more than that of control group (0.318±0.012mm), the displacement of1000N in the experimental group(0.416±0.012mm) was more than that of control group (0.411±0.025mm), butthere were no significant statistic difference in the both groups (p>0.05). Allspecimens were successfully completed cycle experiments, no internal fatigueand failure appeared. After the cycle test, the torque of3°in the experimentalgroup (10.568±1.614Nm) was more than that of control group (10.009±1.323Nm), the torque of5°in the experimental group (14.990±1.417Nm) was morethan that of control group (13.840±1.200Nm), and the difference between twogroups were statistically significant (p <0.05). In vertical compressionexperiments, the displacement of700N in the experimental group(0.264±0.018mm) was less than that of control group (0.273±0.019mm), thedisplacement of1000N in the experimental group (0.348±0.022) was less thanthat of control group (0.368±0.015mm), but there were no significant statisticdifference in the both groups (p>0.05). The maximum load of theexperimental group (2693.6±354.8N) is greater than the maximum load ofthe control group (2578.8±268.9N), the difference was not statisticallysignificant (P>0.05).Conclusion:The biomechanical stability of the magnesium stent issuperior to the iliac bar transplantation, and provides a theoretical basis forclinical application.Part2An animal experimental study of magnesium stent degradationand osteogenesisObjective:To observe the biodegradable and osteogenic properties ofmagnesium stent under in-vivo conditions.Methods:Twelve six-month old male New Zealand White rabbits fromthe Laboratory Animal Center of Hebei Medical University were used in thisstudy. They were randomly divided into two groups. Their average weightswere approximately2.5-2.8kg and the chosen operation site was the femoralcondyle of the right side. The six rabbits of experimental group wereimplanted with porous magnesium stents,the other six rubbits of the controlgroup were implanted hydroxyapatite stents. Serial time points of1week,2 weeks,3weeks,1months,2months and3months were set to monitormagnesium stent degradation and new bone formation. The operation sites ofthe rabbits were shaved. All rubbits were anaesthetized with a1.0%pentobarbital sodium solution(30mg/kg) by ear vein injection. Afteranaesthesia,1%povidone-iodine disinfection and draping. A1.0cmlongitudinal incision was done through lateral of right knee. Muscle tissue wasretracted to expose femoral lateral condyle, A hand driller was used to drill ahole5mm in depth, with the diameter of6mm. Subsequently, the magnesiumstent was implanted into the prepared hole,and the wound was suturedlayer-by-layer covered with sterile dressing. the rubbits of control group weretreated with the same surgical method. After the operation, all rabbits receivedsubcutaneous injections of1mg/kg gentamicin. At each of the serial timepoints, X-ray radiographyand CT was conducted at right femoral condyles inorder to monitor stent degradation, new bone formation and gas production.Blood samples were taken from the rubbits before the implantation and1week,2weeks,3weeks,1month,2months, and3months postoperatively,respectively. Serum magnesium,alanine aminotransferase (ALT), CREA,andblood urea nitrogen (BUN)were conducted on an OLYMPUS AU-1000automatic biochemical analyzer. All the rabbits were sacrificed3monthspostoperatively,heart, kidney, spleen and liver tissue from the rabbits wereinspected with HE staining to verify whether degradation of the magnesiumstent harmed these important visceral organs. The bone samples with implantswere harvested and scanned in a micro-computed tomography device(Skyscan1172,Skyscan Company) to view the extent of corrosion of thesamples as well as new bone growth. The embedded samples were then cutinto sections with a thickness of50-70um thickness. The sectioned sampleswere stained with gimesa Methylene blue-magenta stain. The morphologicaland histological analyses were performed and viewed under a lightmicroscope to observe for any bone on-growth and integration with the hosttissue. SPSS statistical software (Version13.0) was used for dataanalysis.Probability values less than0.05were considered significant. Results:There was bubbles appeared in the X-ray of New Zealand whiterabbits in the experimental group2weeks later,and there was no gas formationin the control group. there were no statistical difference in the serummagnesium concentrations, ALT, BUN and CREA between the experimentalgroup and control group(P>0.05). All the HE stained slices of heart, liver,kidney and spleen were normal, which suggests good biocompatibility of themagnesium stent. There was more new bone formation in the magnesiumgroup than the hydroxyapatite group. The agnesium stents degradated mainlyfrom the outside to inside, the new bone were ingrowed following thedegradation of magnesium stent. There were little degradation of magnesiumstent and new bone formation from the inside to outside. The hydroxyapatitestent is not degraded,and there were fewer osteoblasts scattered on its surface.Conclusion: The experiments preliminarily confirmed that themagnesium stent has good performance of degradation and osteogenesis,which is a promising biodegradable materials to promote fracture healing.Part3The design of quantitative score table for surgical decision of adultfemoral neck fracture and its preliminary clinical applicationObjective:A quantitative score table for surgical decision of adultfemoral neck fracture was designed and used for retrospective analysis offemoral neck fracture patients to evaluate its consistency and significance withclinical practise.Methods:According to the quantitative score table,700patients offemoral neck fractures were analyzed in our hospital from January2007toApril2010,of which met with the inclusion criteria were502cases.All the502cases were divided into four groups according to scores and the actualtreatment status,which were low score internal fixation group (LSIF) with281cases,total hip replacement group(THA) with94cases, hemiarthroplastygroup(HA) with119cases,high score internal fixation group(HSIF) with8cases. Each group was further divided into consistent group and inconsistentgroup basised on whether their actual treatment was in accordance withquantitative score table or not.The operative time, blood loss, blood transfusion, infection rate, reoperation rate, mortality rate, Harris Hip Scoreand so on were recorded and compared between the consistent group andinconsistent group of LSIF,THA and HA respectively.Results: The502patients were followed up for1.0to4.5(averaged3.2y)years.The Kappa value was0.549(0.4~0.75) in consistency test, whichindicated quantitative score table was in consistent with clinical treatment. InLSIF: The nonunion rate,femoral head necrosis rate, reoperation rate,excellent (good) rate and Harris Hip Score of consistent group andinconsistent group were (1.2%vs17.9%),(7.4%vs33.3%),(7.0%vs41.0%),(79.8%vs35.9%),(86.4±9.9vs74.8±10.8) repectively, there was significantstatistical differences (P <0.05). In THR: the revision rate,excellent (good)rate and Harris Hip Score of consistent group and inconsistent group were(1.6%vs18.2%),(96.7%vs75.8%),(92.0±6.3vs85.9±11.6) respectively,therewas significant statistical differences (P <0.05).In HA: the revision rate of theconsistent group rates (5.5%) was less than that of the inconsistent group(18.8%), There was significant statistical differences (P <0.05).Conclusion:The quantitative score table is in keeping with clinicaltreatment. It has obvious significance for the surgical decision making of thefemoral neck fracture.Part4A quantitative score system(qss) of the surgical decision on adultfemoral neck fractures-a two-year prospective study with375casesObjective:to reveal whether patients treated with a quantitative scoresystem for adult femoral neck fractures had a lower revision rate than thosefrom the meta-analysis.Methods:Three hundred seventy-five adult femoral neck fractures weretreated on the basis of QSS for this2-year prospective study. Of these,242were treated with low-score internal fixation,60with THA,55withhemiarthroplasty, and18with high-score internal fixation.Follow-up wascarried out at6weeks,1year, and2years after operation. At each follow-upinterval, revision rates, major postoperative complications, minorpostoperative complications,1and2-year mortality rate after operation, and1 and2-year Harris Hip score (HHS) after operation were documented in thecase record forms. SPSS statistical software (Version13.0) was used for dataanalysis.Probability values less than0.05were considered significant.Results:The revision rates2years postoperatively in the low-scoreinternal fixation, THA, and hemiarthroplasty groups were15.3%,5.0%, and5.5%, respectively, which were lower than those from a meta-analysis(internal fixation,35%; THA,16%).Conclusion:This QSS helps surgical decision making regarding thetreatment choice for adult patients with femoral neck fractures, and goodresults in preliminary clinical practice have been achieved.