A Modification And Validation Of Quantitative Morphometry System For Osteoporotic Vertebral Fractures

Osteoporotic vertebral fracture(OVF)is a serious manifestation of osteoporosis in senile population?OVF can occur without injury.(mainly from low trauma),and is associated with increased morbidity and long term mortality in patients.However,most OVFs could not be diagnosed properly and are missed in clinical practice.Therefore,timely identification of individuals with OVF is of great significance in both clinical practice and research purpose.Generally,two main approaches are employed to the diagnosis of vertebral fracture:semiquantitative(SQ)and quantitative morphometry(QM)methods SQ can be utilized in individual patient effectively,but it becomes inefficient when applied to a large population studies for the limitation of experienced observers.In contrary,QM depends on the comparison of objective parameters of vertebral morphometry to normal values,which can be performed by radiologists as well as clinicians.For QM system,the race-and gender-specific normal values as well as strict criteria for classification of types and grades were two of greatest importance in practice.Established QM systems shared shortcomings such as diverse systems with distinguished criteria and various normal vertebral values.Moreover,seldom had focus on the obtaining of data from Mainland Chinese(Chin.)population.In this study,our theme are:(1)establishment of normal vertebral values of Chin.Population;(2)Modification of Quantitative Morphometry System and checking its reliability;(3)checking the sensitivity of Modified Quantitative Morphometry(mQM)System,to detect vertebral height changes and to predict cement leakage after patients received Percutaneous Kyphoplasty(PKP).ObjectiveThe objective of this study was to modify QM System and check its reliability and validation so that to search for a new way to assess the OVF in Chin.Population.Methods1.Vertebral heights including anterior height(Ha),middle height(Hm),posterior height(Hp)and were measured from T4 to L5;predicted posterior height(pp)and vertebral height ratios of Ha/Hp(A),Hm/Hp(M)and Hp/pp(p)were calculated from 585 Chin.population(both males and females)for the establishment of normal values and further comparisons.2.Based on the Quantitative Morphometry Systems proposed formally,mQM System was established,in which the fracture types were classified into No Deformity(ND),Anterior Wedge(AW),Posterior Wedge(PW),Biconcavity(BC)and Compression(CP).3.Vertebral heights including Ha,Hm and Hp were measured from the pre-operative lateral radiographs of 309 OVF patients who received PKP.Then,the pp and vertebral height ratios of A,Ha/pp(a),M,Hm/pp(m)and p were calculated.According to the criteria of mQM and SQ systems,we made comparisons of their results and assessed the consistency between them.Then,comparisons of height ratios were made to assess the ability of mQM system to detect height ratios amelioration after PKP.4.Based on the Lateral and anteroposterior radiographs of 309 OVF patients who received PKP post-operatively,an evaluation of the frequency between the fracture type and the post-operative cement leakage was made under mQM system.Results1 The normal vertebral values of Chin.population were gender-,population-and region-specific.All vertebral height values increased step-wisely from T4 to L3,and then decreased in L4 and L5.Despite both genders showed similar trends of height ratios change,the height values of males were higher than those of females(P<0.01)consistently.Vertebral size of Chin.was smaller than that of United Kingdom and United State,but was larger than that of Hong Kong Chinese surprisingly,although these two are commonly recognized as one race.Data from four different population showed similar height ratios in every vertebra.2 mQM system and SQ system shared considerable consistency.The results of Chin.Population indicated that our mQM system was sensitive enough to categorize vertebral morphometry into five fracture types,which had excellent consistency with results from SQ system based on the analysis of Consistency Percentage(97.1%),Concordance Correlation Coefficient(0.941)and kappa-statistical(0.947).3 Clinical validation of mQM systemHeight ratios restoration after PKP were different among five fracture types.Type AW restored anterior and middle parameters(bars of A,a,M,and m)significantly.Meanwhile,type BC restored their heights more medially(bars of a,M,and m).Type CP restored their all five height parameters after PKP.Type PW did not show any significant height ratio change on any parameter though obvious trend of posterior height increase could be detected.Type CP showed the highest cement leakage among the five fracture types of mQM systems,followed by AW,BC,and ND.No leakage was detected in type PW,Moreover,a predictive effect of mQM system on cement leakage was indicated.Conclusions1.We established specific normal values for Chin.population.Moreover,our results indicated the necessity of establishment of normal values not only gender-and population-specific,but also region-specific for quantitative morphometric assessment of OVF.2.We modified the previous QM system into mQM system,and then validated it by demonstrating a strong correlation to the widely accepted SQ system.3.Our current study demonstrated that the height ratios restoration patterns were different among different fracture types,which could be precisely detected by our mQM system.4.Different fracture type might result in different kind of cement leakage,which indicated that mQM system was sensitive to predict cement leakage after patients received PKP.