Lamina Slope Angle Is A Risk Factor for Ligamentum Flavum Hypertrophy in Patients with Lumbar Degenerative Disease: A Retrospective Study

Background.One previous work confirmed that laminar slope angle was associated with the ossification of thoracic ligamentum flavum. Several studies have investigated the relevance of disc degeneration grade, thickness of ligamentum flavum, along with cross section area of multifidus and its fatty infiltration. However, there has been no research between the angle and them. This retrospectivestudyof clinical materials from 122 patients was designed to investigate the influence of laminar slope angle on degeneration of lumbar when eliminating the interference of age.Methods.122 individuals were retrospected randomly on the basis of age difference from 687inpatients scheduled to undergo a lumbar operation between January and December 2017.We registered their age and sex, evaluated and measuredL4-L5 disc degeneration grade,correspondingcross section area of multifidus, muscle-fat index,thickness of ligamentum flavum and laminar slope angle from preoperative magnetic resonance imagingand three-dimensional computer tomography. Independent-sample T tests were used to assess the association between age and measurement indices. The Pearson correlation coefficient, and partial correlation excluding age, was also performed to analyze thecorrelation between clinical parameters.Results.Our results showed that age was positively connected withthe laminar slope angle(L4:r=0.298, p=＜0.01; L5:r=0.303, p=＜0.01). Excluding the interference of age, revealed a credibly negative relationship between the angle of L4 and the thickness of the ligamentum flavum(Left: r=-0.303, p=＜0.01;Right:r=-0.340, p=＜0.01). However, there was no correlationwithother parameters(disc: r=-0.141, p＞0.05; left multifidus: r=0.248, p＞0.05; right multifidus: r=0.225, p＞0.05; left muscle-fat index: r=0.033, p＞0.05; right muscle-fat index: r=0.016, p＞0.05).Conclusion.Excluding the interference of age, Inclination of small laminar slope angle leads to hypertrophy of lumbar ligamentum flavum.LEVEL OF EVIDENCE:Level 4.