| Objective : The tibial tuberosity-trochlear groove(horizontal)distance(TT-TG distance)has always been an important diagnostic criterion for patellar instability,and is now considered by many scholars as the gold standard for the diagnosis of patellar instability.However,it is an absolute value,which be used as the diagnostic criterion to uniformly quantify all patients,but it cannot exclude individual differences in the size of the knee joint of patients,nor can it provide a reference for individualized diagnosis and treatment.There are many problems.Therefore,this study discussed a new diagnostic criterion: the TT-TG/TT-TE ratio(horizontal distance/vertical distance between tibial tuberosity and femoral trochlear groove)to replace the TT-TG distance,and the absolute number was changed to the relative number as the diagnostic criterion,which can provide individual diagnostic criteria and exclude individual differences.The purpose of this study was to investigate the significance of TT-TG/TT-TE in the diagnosis and treatment of patellar instability.Methods:From 2005 to 2018,34 patients with patellar instability and 40 patients with early knee osteoarthritis were selected from the First Affiliated Hospital of Hebei North University,all patients underwent kneeMRI examination.The MRI data was imported into the E-3D digital medical modeling and design system Setup V16.15 software to establish the model.The first MRI cross section of intact cartilage of the femoral trochlear was selected,the lowest point of the femoral trochlear groove(point A)was marked,and then the point was perpendicular(AD)to the tangent line of the posterior femoral condyle(BC).The second MRI cross-sectional section,in which the patellar tendon can be seen fully attached to the tibial tuberosity,was used as the midline connecting the attachment points of the patellar tendon to the internal and external attachment points,and intersected at the leading edge of the tibial tuberosity(point E).The two images before and after the measurement mark overlap,the distance from point E to the vertical line AD,EO is the TT-TG distance.Because O point and E point are on the same horizontal plane,the coordinate value of Z axis is the same,the above A point and E point are found,the software uses the coordinate value of Z axis of A point and E point to subtract AO vertical distance(that is,TT-TE distance).The ratio of TT-TG distance to TT-TE distance is TT-TG /TT-TE.The differences of TT-TG distance,TT-TE distance and TT-TG/TT-TE ratio between the two groups were compared.Results : The TT-TG distance of the patella instability group was16.92±4.41 mm,the TT-TG / TT-TE was 0.30±0.04,the TT-TG distance of the patella stabilization group was 10.23±3.14 mm,and the TT-TG / TT-TE was 0.18±0.03,the TT-TG distance and TT-TG/TT-TE distance betweenthe two groups were statistically significant(P<0.05).The TT-TE distances of the patella instability group and the patella stabilization group were56.95±5.93 mm and 55.57±6.46 mm,respectively.There was no significant difference in TT-TE distance between the two groups(P> 0.05).Conclusion : 1.The TT-TG/TT-TE ratio constitutes the hook-femoral triangle structure,which largely determines the biomechanical characteristics of the patellofemoral joint and is more closely related to the function of the patellofemoral joint.Therefore,the TT-TG/TT-TE ratio is better than the TT-TG distance to reflect the functional characteristics of the patellofemoral joint,and has more biomechanical significance and diagnostic value.2.The relative value of TT-TG/TT-TE ratio was used to replace the absolute value of TT-TG distance to diagnose patella instability,which can exclude individual differences in the size of patients’ knee joints.It is an individual diagnostic standard.3.The relative value of TT-TG/TT-TE as the diagnostic standard is helpful to assess the severity of each patient’s condition and determine whether to perform intradermal tibial tuberosity surgery,which is conducive to individual treatment.4.Hospital nuclear magnetic equipment(Full digital PHILIPS 3.0T superconducting MRI)could not measure the TT-TG/TT-TE ratio,while the finite element software was used to establish a 3D model to complete the measurement and calculation.The software is advanced in data measurement,processing and analysis,which is in the leading level of digital medicine and has been widely used in orthopaedic research.The results of this experiment provide reference for future clinical diagnosis and treatment,and the research method using finite element software is also in line with the development trend of digital orthopedic medicine in the future. |
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