Finite element analysis-based orthopedic internal fixation screw looseness prediction method and system

Abstract

The invention relates to the technical field of intelligent medical treatment, in particular to an orthopedic internal fixation screw looseness prediction method and system based on finite element analysis, and the method comprises the steps: analyzing a bone image of a patient in a historical collection period, and determining an abnormal sub-period in the historical collection period according to the displacement of a screw key node and a bone tissue key node; analyzing the number of abnormal sub-periods in the historical acquisition period and an interface slip ratio, and identifying a fastening screw; analyzing the change rate of the interface slip value of the fastening screw in the historical acquisition time period, judging whether the change rate is uniform or not, and outputting a prediction time point according to a change rate uniformity judgment result; according to the method, the adjustment remaining time is determined through processing and analysis according to the predicted time period point, the doctor can select to tighten the screw again or replace the screw according to the specific condition of the patient before the adjustment remaining time is calculated, a clear and scientific time basis is provided for the clinical decision of the doctor, and the timeliness and effectiveness of treatment are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of intelligent medicine, and particularly to a method and system for predicting loosening of orthopedic internal fixation screws based on finite element analysis. Background Art

[0002] Orthopedic internal fixation surgery, as an important means for treating orthopedic diseases such as fractures and spinal diseases, is widely used in clinical practice. The stability of internal fixation screws plays a decisive role in the surgical treatment effect. However, screw loosening is a common and troublesome postoperative complication, which not only causes increased pain and prolonged healing period for patients, but also requires secondary surgery in severe cases, bringing great pain and economic burden to patients.

[0003] With the continuous development of finite element analysis technology, its application in the medical field has become more and more in-depth, providing a new way for predicting loosening of orthopedic internal fixation screws. At present, although certain progress has been made in the orthopedic internal fixation screw loosening prediction system based on finite element analysis, there are still many deficiencies. In the process of analysis and judgment, the existing system does not quantify the mechanical changes at the contact interface between the screw and the bone accurately enough, resulting in difficulty in accurately judging the tightness state of the screw. Doctors can only make subjective judgments based on experience, increasing the risk of misdiagnosis. In terms of data mining, the historical data is not fully utilized, and abnormal data cannot be captured in time, missing the best intervention opportunity. In addition, the existing system does not comprehensively analyze the dynamic changes of screw loosening, cannot effectively judge the characteristics of the change rate of the interface slip value, the prediction method is single and the accuracy is poor, and it cannot provide doctors with a clear prediction time point and a scientific remaining adjustment time, greatly limiting the scientific nature and timeliness of clinical decision-making.

[0004] Therefore, we propose a method and system for predicting loosening of orthopedic internal fixation screws based on finite element analysis. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for predicting loosening of orthopedic internal fixation screws based on finite element analysis to solve at least one of the above-mentioned existing technical problems.

[0006] The present invention provides a method for predicting loosening of orthopedic internal fixation screws based on finite element analysis, including:

[0007] Analyze the bone images of patients in the historical acquisition period, and determine the abnormal sub-periods within the historical acquisition period according to the displacement amounts of the key nodes of the screw and the key nodes of the bone tissue;

[0008] Analyze the number of abnormal sub-periods and the interface slip ratio within the historical acquisition period, judge the tightness state of the orthopedic internal fixation screws and identify the tightened screws among the fixed screws;

[0009] Analyze the change rate of the interface slip value of the fastening screw during the historical acquisition period, judge whether the change rate is uniform, and output the predicted time point according to the judgment result of the uniform change rate;

[0010] According to the predicted time point, process and analyze to determine the remaining adjustment time.

[0011] As a further solution of the present invention: the process of obtaining the abnormal sub-period is as follows:

[0012] Analyze the bone image of the patient during the historical acquisition period, output the interface slip value, and perform a ratio calculation with the interface slip threshold to obtain the interface slip ratio of the contact interface. If the interface slip ratio is greater than or equal to the interface slip ratio threshold, the corresponding acquisition sub-period is recorded as an abnormal sub-period.

[0013] As a further solution of the present invention: the process of obtaining the interface slip value is as follows:

[0014] The time period between adjacent acquisition time points during the historical acquisition period is recorded as an acquisition sub-period;

[0015] Within the acquisition sub-period, measure the displacement of the key nodes of the screw and the key nodes of the bone tissue, and perform deviation processing to obtain the displacement deviation;

[0016] According to the displacement deviation, calculate the interface slip value of the contact interface within the acquisition sub-period.

[0017] As a further solution of the present invention: the process of obtaining the tightness state of the orthopedic internal fixation screw is as follows:

[0018] Analyze the number of abnormal sub-periods and the interface slip ratio during the historical acquisition period, output the abnormal period number ratio and the slip degree ratio during the historical acquisition period, and perform a product process to obtain the screw tightness value.

[0019] As a further solution of the present invention: the process of obtaining the abnormal period number ratio and the slip degree ratio during the historical acquisition period is as follows:

[0020] Calculate the proportion of abnormal sub-periods during the historical acquisition period to obtain the abnormal period number ratio;

[0021] Subtract the interface slip ratio corresponding to the abnormal sub-period from the interface slip ratio threshold to obtain the interface slip deviation value. Sum and average the interface slip deviation values of all abnormal sub-periods, and then perform a ratio process with the interface slip ratio threshold to obtain the slip degree ratio.

[0022] As a further solution of the present invention: the process of judging whether the change rate is uniform is as follows:

[0023] Analyze the interface slip values during the historical acquisition period, obtain the standard deviation and average value of the change rate of the interface slip values during the historical acquisition period, perform a ratio process, and output the coefficient of variation of the change rate; if the coefficient of variation is greater than or equal to the coefficient of variation threshold, it indicates that the change rate is uniform during the historical acquisition period, otherwise, it indicates that the change rate is non-uniform during the historical acquisition period.

[0024] As a further solution of the present invention: the process of obtaining the standard deviation and average value of the change rate of the interface slip values during the historical acquisition period is as follows:

[0025] Obtain the interface slip value sequence during the historical acquisition period, calculate the change rate of the interface slip values in the acquisition sub-periods and integrate them into a change rate sequence, calculate the average value of the change rate, and then calculate the standard deviation of the change rate.

[0026] As a further solution of the present invention: the process of obtaining the remaining time adjustment is as follows:

[0027] Based on the non-uniform change rate, extract the maximum change rate in the change rate sequence table as the predicted change rate; calculate the ratio of the interface slip threshold to the predicted change rate to obtain the predicted time point;

[0028] Based on the uniform change rate, determine whether the change rate of the interface slip values during the historical acquisition period is linearly changing;

[0029] Based on the linear change, input the interface slip threshold as y into the fitting straight line equation and output the x value of the predicted time point; based on the non-linear change, construct a prediction model, use the trained model, input the interface slip threshold, and output the predicted time point when reaching the interface slip threshold; perform a difference process on the predicted time point and the current time point to obtain the adjusted remaining time.

[0030] As a further solution of the present invention: the specific process of determining whether the change rate of the interface slip values during the historical acquisition period is linearly changing is as follows:

[0031] Perform linear fitting on the change rate of the interface slip values during the historical acquisition period by the least squares method, calculate the goodness of fit. If the goodness of fit is greater than or equal to the goodness of fit threshold, the change rate of the interface slip values is linearly changing during the historical acquisition period, otherwise, it is non-linearly changing.

[0032] The present invention provides an orthopedic internal fixation screw loosening prediction system based on finite element analysis, including:

[0033] Abnormality analysis module: Analyze the bone images of the patient during the historical acquisition period, and determine the abnormal sub-periods during the historical acquisition period according to the displacement amounts of the key screw nodes and the key bone tissue nodes;

[0034] Tightness state judgment module: Analyze the number of abnormal sub-periods and the interface slip ratio during the historical acquisition period, judge the tightness state of orthopedic internal fixation screws, and identify the tightened screws among the fixation screws;

[0035] Change uniformity analysis module: Analyze the change rate of the interface slip value of the tightened screws during the historical acquisition period, judge whether the change rate is uniform, and output the predicted time point according to the judgment result of the uniform change rate;

[0036] Adjustment remaining time determination module: Determine the adjustment remaining time based on the predicted time point through processing and analysis.

[0037] Advantages of the present invention:

[0038] 1. By analyzing the bone images of the patient during the historical acquisition period, the present invention determines the abnormal sub-periods during the historical acquisition period; analyzes the number of abnormal sub-periods and the interface slip ratio during the historical acquisition period, and judges the tightness state of orthopedic internal fixation screws; by measuring the displacement amounts of the key nodes of the screws and the key nodes of the bone tissue, and calculating the displacement deviation and the interface slip value, the slip situation of the contact interface can be accurately quantified, making the analysis result more accurate, which is beneficial to effectively judging the tightness state of orthopedic internal fixation screws, providing a clear decision-making basis for doctors. Based on the historical data of the loosening change of orthopedic internal fixation screws, comprehensive analysis and processing are carried out, and the abnormal sub-periods during the historical acquisition period can be detected in time, so as to timely detect the possible loosening of the screws, which helps doctors take measures in time to avoid the adverse consequences caused by screw loosening, and improve the treatment effect and the safety of patients.

[0039] 2. The present invention analyzes the change rate of the interface slip value of the fastening screw during the historical acquisition period, and judges whether the change rate is uniform; according to the judgment result of whether the change rate of the interface slip value is uniform during the historical acquisition period, the predicted time point is output; according to the predicted time point, the remaining adjustment time is determined through processing and analysis. By calculating the change rate of the interface slip value, the present invention can accurately judge whether the change rate of the interface slip value is uniform during the historical acquisition period, so as to clearly master its change state, which helps to deeply understand the interface slip characteristics of the fastening screw during the historical acquisition period. When the change rate of the interface slip value is not uniform, the maximum change rate is used as the predicted change rate to calculate the predicted time point, which can minimize the risk brought by the loosening of the orthopedic internal fixation screw in the case of the fastest screw loosening rate, enabling medical staff to evaluate the time point when the interface slip value reaches the threshold, take measures in advance to avoid the situation of fixed screw loosening in patients, and promote the recovery of patients. When the change rate of the interface slip value is uniform, the least squares method is used for linear fitting and the change type is judged through the goodness of fit. If it is a linear change, the predicted time point is predicted based on the fitting straight line equation; if it is a non-linear change, an LSTM neural network prediction model is constructed for prediction, and then the time point when the interface slip value reaches the interface slip threshold is accurately predicted. Based on the predicted time point, the remaining adjustment time is calculated. Doctors can choose to re-tighten the screw or replace the screw according to the specific situation of the patient before the end of this time, which provides a clear and scientific time basis for doctors' clinical decisions and improves the timeliness and effectiveness of treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0041] Figure 1 It is the method flow chart of the orthopedic internal fixation screw loosening prediction method based on finite element analysis in the embodiment of the present invention;

[0042] Figure 2 It is the system block diagram of the orthopedic internal fixation screw loosening prediction system based on finite element analysis in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] To enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solution in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0044] Embodiment 1

[0045] As Figure 1 shown, the method for predicting the loosening of orthopedic internal fixation screws based on finite element analysis provided by the embodiment of the present invention specifically includes:

[0046] Step 1: Analyze the bone images of the patient during the historical acquisition period, and determine the abnormal sub-periods during the historical acquisition period;

[0047] Set the historical acquisition period, set several acquisition time points at equal time intervals during the historical acquisition period, obtain the bone images of the patient through a spiral CT scanner, use the three-dimensional modeling software SolidWorks to establish a three-dimensional model of the bone fixation screw and the surrounding bone, import the model into the finite element analysis software ANSYS, define the material properties, assign corresponding elastic modulus, Poisson's ratio and other parameters to the screw and the bone, perform mesh division, use a finer mesh for the screw and the bone at the key parts to improve the calculation accuracy, apply boundary conditions and loads, and simulate the stress situation of the bone fixation screw under actual working conditions;

[0048] It should be noted that the historical acquisition period includes but is not limited to 10 days, 20 days, 30 days;

[0049] Calculate the stress distribution of the model through the solver of the finite element software, extract the stress values of each part of the screw from the post-processing module, use the CONTACT unit of ANSYS, select the nodes associated with the contact unit through the ESLN command, and record them as the key nodes of the screw, and record the surface nodes of the bone in contact with the screw as the key nodes of the bone tissue;

[0050] It should be noted that the key nodes of the screw and the surface nodes of the bone are in one-to-one correspondence;

[0051] Generate a displacement nephogram through NODAL SOLUTION→U-Total, and record the time period between adjacent acquisition time points as the acquisition sub-period;

[0052] During the acquisition sub-period, measure the displacement of the key nodes of the screw, denoted as the screw node displacement U B ; Measure the displacement of the key nodes of the bone tissue, denoted as the bone tissue node displacement U S ;

[0053] Calculate the displacement U of the screw node B And the displacement U of the bone tissue node S The displacement deviation ΔU, and the specific calculation formula is:

[0054] ΔU = U B - U S

[0055] Furthermore, calculate the interface slip value d of the contact interface within the acquisition sub-period, i = 1, 2,..., n, where n represents the total number of key screw nodes, and the specific calculation formula is:

[0056]

[0057] Set the interface slip threshold, where the interface slip threshold is set by those skilled in the art according to the historical data of the loosening change of orthopedic internal fixation screws;

[0058] Perform a ratio process on the interface slip value and the interface slip threshold to obtain the interface slip ratio of the contact interface;

[0059] In some embodiments, compare the interface slip ratio with the interface slip ratio threshold, and the specific comparison process is:

[0060] If the interface slip ratio is greater than or equal to the interface slip ratio threshold, mark the corresponding acquisition sub-period as an abnormal sub-period;

[0061] If the interface slip ratio is less than the interface slip ratio threshold, mark the corresponding acquisition sub-period as a normal sub-period;

[0062] Step 2: Analyze the number of abnormal sub-periods and the interface slip ratio within the historical acquisition period, and judge the tightness state of the orthopedic internal fixation screw;

[0063] Count the number of abnormal sub-periods within the historical acquisition period, and perform a ratio process with the total number of acquisition sub-periods within the historical acquisition period to obtain the abnormal period number ratio within the historical acquisition period;

[0064] Extract the interface slip ratio corresponding to the abnormal sub-period, and perform a difference process with the interface slip ratio threshold to obtain the interface slip deviation value. Sum and average the interface slip deviation values corresponding to all abnormal sub-periods to obtain the average interface slip deviation. Perform a ratio process on the average interface slip deviation and the interface slip ratio threshold to obtain the slip degree ratio of the contact interface within the historical acquisition period;

[0065] Perform a product process on the abnormal period number ratio within the historical acquisition period and the slip degree ratio of the contact interface within the historical acquisition period to obtain the screw tightness value;

[0066] In some embodiments, a screw tightening threshold is set, and the screw tightening value is compared with the screw tightening threshold. The specific comparison process is as follows:

[0067] If the screw tightening value is greater than or equal to the screw tightening threshold, the fixing screw is recorded as a loose screw, and the doctor can choose to re-tighten the screw or replace the screw according to the specific situation of the patient;

[0068] If the screw tightening value is less than the screw tightening threshold, the fixing screw is recorded as a tightened screw;

[0069] The technical solution of this embodiment is as follows: Analyze the bone images of the patient in the historical acquisition period to determine the abnormal sub-periods within the historical acquisition period; Analyze the number of abnormal sub-periods and the interface slip ratio within the historical acquisition period to judge the tightening state of the orthopedic internal fixation screw; Through the measurement of the displacement of the key nodes of the screw and the key nodes of the bone tissue, as well as the calculation of the displacement deviation and the interface slip value, the present invention can accurately quantify the slip situation of the contact interface, make the analysis result more accurate, be conducive to effectively judging the tightening state of the orthopedic internal fixation screw, provide a clear decision-making basis for the doctor, and based on the historical orthopedic internal fixation screw loosening change data, conduct comprehensive analysis and processing, can timely discover the abnormal sub-periods within the historical acquisition period, thereby timely detecting the possible loosening of the screw, helping the doctor take measures in time, avoiding the adverse consequences caused by screw loosening, and improving the treatment effect and the safety of the patient.

[0070] Example Two

[0071] As Figure 1 shown, the method for predicting loosening of orthopedic internal fixation screws based on finite element analysis provided by the embodiment of the present invention specifically includes:

[0072] Step Three: Analyze the change rate of the interface slip value of the tightened screw within the historical acquisition period, and judge whether the change rate is uniform;

[0073] In some embodiments, all the acquisition sub-periods are integrated into an acquisition sub-period sequence {t1, t2,..., t j ,..., t m}, j = 1, 2,..., m, where m represents the number of acquisition sub-periods, and an interface slip value sequence {d1, d2,..., d j ,..., d m} within the historical acquisition period is obtained, where d j represents the displacement corresponding to the j-th acquisition sub-period;

[0074] Through the formula: the change rate v j of the j-th acquisition sub-period is calculated;

[0075] Integrate the change rates of the interface slip values in all collected sub - time periods into a change rate sequence {v1, v2, …, v j , …, v m};

[0076] Extract the change rate of the interface slip value from the change rate sequence table, and calculate the average value of the change rate of the interface slip value within the historical collection period The specific calculation formula is:

[0077]

[0078] Furthermore, calculate the standard deviation σ of the change rate of the interface slip value within the historical collection period. The specific calculation formula is:

[0079]

[0080] Perform a ratio process on the standard deviation σ of the change rate of the interface slip value within the historical collection period and the average value of the change rate of the interface slip value within the historical collection period to obtain the coefficient of variation of the change rate of the interface slip value within the historical collection period;

[0081] In some embodiments, compare the coefficient of variation of the change rate of the interface slip value within the historical collection period with the coefficient of variation threshold of the change rate of the interface slip value within the historical collection period;

[0082] If the coefficient of variation of the change rate of the interface slip value within the historical collection period is greater than or equal to the coefficient of variation threshold of the change rate of the interface slip value within the historical collection period, it indicates that the change rate of the interface slip value within the historical collection period is uniform;

[0083] If the coefficient of variation of the change rate of the interface slip value within the historical collection period is less than the coefficient of variation threshold of the change rate of the interface slip value within the historical collection period, it indicates that the change rate of the interface slip value within the historical collection period is non - uniform;

[0084] It should be noted that the role of obtaining the coefficient of variation of the change rate of the interface slip value within the historical collection period is as follows:

[0085] Role 1: Through the comparison and judgment of the coefficient of variation of the change rate of the interface slip value within the historical collection period, it is beneficial to analyze whether the change rate of the interface slip value within the historical collection period is uniform, and further, the change state of the change rate of the interface slip value within the historical collection period can be grasped;

[0086] Role 2: Through the comparison and judgment of the coefficient of variation of the change rate of the interface slip value within the historical collection period, it is beneficial to analyze whether the change rate of the interface slip value within the historical collection period is uniform, and it is convenient to determine the adjustment of the remaining time according to whether the change rate of the interface slip value within the historical collection period is uniform;

[0087] Step 4: Output the predicted time point according to the judgment result on whether the change rate of the interface slip value is uniform during the historical acquisition period;

[0088] S41. Based on the non-uniform change rate of the interface slip value during the historical acquisition period, continue to monitor the subsequent interface slip values, obtain the maximum change rate in the change rate sequence table, and use the maximum change rate as the predicted change rate;

[0089] Calculate the ratio of the interface slip threshold to the predicted change rate to obtain the predicted time point;

[0090] It should be noted that the purpose of using the maximum change rate as the predicted change rate is that in the case of the fastest loosening rate of the orthopedic internal fixation screw, the risk brought by the loosening of the orthopedic internal fixation screw can be minimized to the greatest extent, which is beneficial for medical staff to be able to evaluate the time point when the interface slip value reaches the interface slip threshold. Furthermore, it enables medical staff to choose to re-tighten the screw or replace the screw according to the specific situation of the orthopedic patient before the time point when the interface slip value reaches the interface slip threshold, avoiding the situation of loosening of the fixation screw in orthopedic patients and being beneficial for the recovery of the patient;

[0091] S42. Based on the uniform change rate of the interface slip value during the historical acquisition period, judge whether the change rate of the interface slip value during the historical acquisition period shows a linear change;

[0092] Perform linear fitting on the change rate of the interface slip value during the historical acquisition period by the least squares method, where the fitting straight line equation is y = ax + b;

[0093] Calculate the goodness of fit R 2 , and the specific calculation formula is:

[0094]

[0095] where l represents the total number of data points for linear fitting, y k is the kth actual value, represents the kth predicted value, represents the average value of the actual values;

[0096] Set the goodness-of-fit threshold, and compare the goodness of fit with the goodness-of-fit threshold. The specific comparison process is as follows:

[0097] If the goodness of fit is greater than or equal to the goodness-of-fit threshold, it indicates that the fitting degree between the change rate of the interface slip value and the fitting straight line is relatively high, and the change rate of the interface slip value shows a linear change during the historical acquisition period;

[0098] If the goodness of fit is less than the goodness-of-fit threshold, it indicates that the fitting degree between the change rate of the interface slip value and the fitting line is low, and the change rate of the interface slip value shows a non-linear change during the historical acquisition period;

[0099] Based on the linear change, according to the fitting line equation y = ax + b, predict the time point when the interface slip value reaches the interface slip threshold. Take the interface slip threshold as y and output the x value, which is the predicted time point;

[0100] Based on the non-linear change, build a prediction model based on the LSTM neural network;

[0101] After normalizing the change rate of the interface slip value during the historical acquisition period, convert the data into a format suitable for input to the LSTM model [number of samples, time steps, number of features]; divide it into a training set, a validation set, and a test set according to the ratio of 8:1:1;

[0102] Use the training set to train the model. During the training process, monitor the performance of the model through the validation set and evaluate the performance of the model using the test set. The specific evaluation metrics are:

[0103] Calculate the mean square error. The specific calculation formula is:

[0104]

[0105] where, M c represents the actual observed value of the c-th sample, represents the predicted value (model output value) of the c-th sample, and N represents the total number of samples;

[0106] Furthermore, the loss function during the model training process is obtained as:

[0107]

[0108] where, d represents the time step, T represents the total number of time steps of the time series, represents the mean square error of the d-th time step;

[0109] Use the trained model, take the interface slip threshold as the input, and output the predicted time point when reaching the interface slip threshold;

[0110] Step Five: According to the predicted time period point, process and analyze to determine the remaining adjustment time;

[0111] Based on the obtained predicted time point, subtract the current time point from the predicted time point to obtain the remaining adjustment time. The doctor needs to choose to re-tighten the screw or replace the screw according to the specific situation of the patient before the end of the remaining adjustment time;

[0112] The technical solution of this embodiment is as follows: Analyze the change rate of the interface slip value of the fastening screw during the historical acquisition period, and judge whether the change rate is uniform; According to the judgment result of whether the change rate of the interface slip value is uniform during the historical acquisition period, output the predicted time point; According to the predicted time point, process and analyze to determine the remaining adjustment time. By calculating the change rate of the interface slip value, the present invention can accurately judge whether the change rate of the interface slip value is uniform during the historical acquisition period, so as to clearly grasp its change state, which helps to deeply understand the interface slip characteristics of the fastening screw during the historical acquisition period. When the change rate of the interface slip value is not uniform, the maximum change rate is used as the predicted change rate to calculate the predicted time point, which can minimize the risk brought by the loosening of orthopedic internal fixation screws in the case of the fastest screw loosening rate, enabling medical staff to evaluate the time point when the interface slip value reaches the threshold, take measures in advance, avoid the situation of fixed screw loosening for patients, and promote the recovery of patients. When the change rate of the interface slip value is uniform, the least square method is used for linear fitting and the change type is judged by the goodness of fit. If it is a linear change, the predicted time point is predicted based on the fitting straight line equation; If it is a non-linear change, an LSTM neural network prediction model is constructed for prediction, and then the time point when the interface slip value reaches the interface slip threshold is accurately predicted. Based on the predicted time point, the remaining adjustment time is calculated. Doctors can choose to re-tighten the screws or replace the screws according to the specific situation of the patient before the end of this time, providing a clear and scientific time basis for doctors' clinical decisions and improving the timeliness and effectiveness of treatment.

[0113] Example Three in Real Time

[0114] As Figure 2 shown, the orthopedic internal fixation screw loosening prediction system based on finite element analysis provided by the embodiment of the present invention specifically includes:

[0115] Abnormal analysis module: Analyze the bone images of the patient during the historical acquisition period, and determine the abnormal sub-period during the historical acquisition period according to the displacement amounts of the key nodes of the screw and the key nodes of the bone tissue;

[0116] Tightening and loosening state judgment module: Analyze the number of abnormal sub-periods and the interface slip ratio during the historical acquisition period, judge the tightening and loosening state of the orthopedic internal fixation screw, and identify the fastening screw among the fixed screws;

[0117] Change uniformity analysis module: Analyze the change rate of the interface slip value of the fastening screw during the historical acquisition period, and judge whether the change rate is uniform;

[0118] Predicted time point output module: Output the predicted time point according to the judgment result of change rate uniformity;

[0119] Remaining adjustment time determination module: Process and analyze to determine the remaining adjustment time according to the predicted time point.

[0120] The above formulas are all dimensionless and only take their numerical values for calculation. The formulas are obtained by collecting a large amount of data and performing software simulation to get a formula that is closest to the actual situation. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0121] The above has described in detail an embodiment of the present invention, but the content described is only a preferred embodiment of the present invention and cannot be considered as limiting the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. A method for predicting loosening of orthopedic internal fixation screws based on finite element analysis, characterized in that, Including: Analyze the bone images of patients in the historical acquisition period, and determine the abnormal sub-periods within the historical acquisition period according to the displacement amounts of the screw key nodes and the bone tissue key nodes. Analyze the number of abnormal sub-periods and the interface slip ratio within the historical acquisition period, judge the tightness state of the orthopedic internal fixation screws, and identify the tightened screws among the fixation screws. Analyze the change rate of the interface slip value of the tightened screws within the historical acquisition period, judge whether the change rate is uniform, and output the predicted time point according to the judgment result of the uniform change rate. According to the predicted time point, process and analyze to determine the remaining adjustment time.

2. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 1, wherein The process of obtaining the abnormal sub-periods is as follows: Analyze the bone images of patients in the historical acquisition period, output the interface slip value, and perform a ratio calculation with the interface slip threshold to obtain the interface slip ratio of the contact interface. If the interface slip ratio is greater than or equal to the interface slip ratio threshold, record the corresponding acquisition sub-period as an abnormal sub-period.

3. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 2, wherein The process of obtaining the interface slip value is as follows: Record the time period between adjacent acquisition time points within the historical acquisition period as an acquisition sub-period. Within the acquisition sub-period, measure the displacement amounts of the screw key nodes and the bone tissue key nodes, and perform deviation processing to obtain the displacement deviation. According to the displacement deviation, calculate the interface slip value of the contact interface within the acquisition sub-period.

4. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 3, characterized in that, The process of obtaining the tightness state of the orthopedic internal fixation screws is as follows: Analyze the number of abnormal sub-periods and the interface slip ratio within the historical acquisition period, output the abnormal period number ratio and the slip degree ratio within the historical acquisition period, and perform a product process to obtain the screw tightness value.

5. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 4, characterized in that The process of obtaining the abnormal period number ratio and the slip degree ratio within the historical acquisition period is as follows: Calculate the proportion of abnormal sub-periods within the historical acquisition period to obtain the abnormal period number ratio. Subtract the interface slip ratio corresponding to the abnormal sub-period from the interface slip ratio threshold to obtain the interface slip deviation value. Sum and average the interface slip deviation values of all abnormal sub-periods, and then perform a ratio process with the interface slip ratio threshold to obtain the slip degree ratio.

6. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 5, wherein The process of judging whether the change rate is uniform is as follows: Analyze the interface slip values within the historical acquisition period, obtain the standard deviation and the average value of the change rate of the interface slip values within the historical acquisition period, and perform a ratio process to output the coefficient of variation of the change rate. If the coefficient of variation is greater than or equal to the coefficient of variation threshold, it indicates that the change rate is uniform within the historical acquisition period; otherwise, it indicates that the change rate is non-uniform within the historical acquisition period.

7. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 6, wherein The process of obtaining the standard deviation and the average value of the change rate of the interface slip values within the historical acquisition period is as follows: Obtain the interface slip value sequence within the historical acquisition period, calculate the change rate of the interface slip values of the acquisition sub-periods and integrate them into a change rate sequence, calculate the average value of the change rate, and then calculate the standard deviation of the change rate.

8. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 7, characterized in that, The process of obtaining the remaining adjustment time is as follows: Based on the non-uniform change rate, extract the maximum change rate in the change rate sequence table as the predicted change rate; perform a ratio calculation with the interface slip threshold and the predicted change rate to obtain the predicted time point. Based on the uniform change rate, judge whether the change rate of the interface slip values within the historical acquisition period is linearly changing. Based on linear variation, the interface slip threshold is used as the y input of the fitted straight-line equation, and the predicted time point x value is output; based on non-linear variation, a prediction model is constructed. Using the trained model, the interface slip threshold is used as the input, and the predicted time point when the interface slip threshold is reached is output; the predicted time point is subtracted from the current time point to obtain the adjusted remaining time.

9. The method for predicting loosening of orthopedic internal fixation screws based on finite element analysis according to claim 8, wherein The specific process for judging whether the change rate of the interface slip value in the historical acquisition period is linearly changing is as follows: The change rate of the interface slip value in the historical acquisition period is linearly fitted by the least squares method, and the goodness of fit is calculated. If the goodness of fit is greater than or equal to the goodness-of-fit threshold, the change rate of the interface slip value is linearly changing in the historical acquisition period; otherwise, it is non-linearly changing.

10. An orthopedic internal fixation screw loosening prediction system based on finite element analysis, which implements the orthopedic internal fixation screw loosening prediction method based on finite element analysis according to any one of claims 1-9, characterized in that, It includes: Abnormality analysis module: Analyze the bone images of the patient in the historical acquisition period, and determine the abnormal sub-period in the historical acquisition period according to the displacement amounts of the key screw nodes and the key bone tissue nodes; Tightness state judgment module: Analyze the number of abnormal sub-periods and the interface slip ratio in the historical acquisition period, judge the tightness state of the orthopedic internal fixation screw, and identify the tightened screw among the fixation screws; Change uniformity analysis module: Analyze the change rate of the interface slip value of the tightened screw in the historical acquisition period, judge whether the change rate is uniform, and output the predicted time point according to the result of the change rate uniformity judgment; Adjusted remaining time determination module: Process and analyze to determine the adjusted remaining time according to the predicted period point.

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