ObjectiveTo review the research progress of indication and treatment of graft in shoulder superior capsular reconstruction (SCR) for rotator cuff tear (RCT).MethodsThe literature related to shoulder SCR in recent years was extensively reviewed, and the anatomy, biomechanics, surgical indications, and treatment of graft in SCR were summarized.ResultsSuperior capsule plays a role as a functional complex with rotator cuff, ligament, and whole capsule. SCR can effectively restore the superior stability of the shoulder. The indications of SCR include the irreparable massive RCT, massive RCT combined with pseudoparalysis shoulder, medium/large RCT with severe degenerative rotator cuff tissue, and dual-layer RCT. In order to achieve a better healing of tendon-bone in graft and decrease the rate of long-term graft retearing, it is essential to select an appropriate thickness graft, fix the graft in right intensity, and get a better capsular continuity.ConclusionThe technique of SCR advanced to SCR for reinforcement and it is indicated from substantial massive RCT to severe degeneration of rotator cuff tissue. Graft treatment is the key step for a successful SCR.
Objective To review the biomechanical research progress of internal fixation of tibial plateau fracture in recent years and provide a reference for the selection of internal fixation in clinic. Methods The literature related to the biomechanical research of internal fixation of tibial plateau fracture at home and abroad was extensively reviewed, and the biomechanical characteristics of the internal fixation mode and position as well as the biomechanical characteristics of different internal fixators, such as screws, plates, and intramedullary nails were summarized and analyzed. Results Tibial plateau fracture is one of the common types of knee fractures. The conventional surgical treatment for tibial plateau fracture is open or closed reduction and internal fixation, which requires anatomical reduction and strong fixation. Anatomical reduction can restore the normal shape of the knee joint; strong fixation provides good biomechanical stability, so that the patient can have early functional exercise, restore knee mobility as early as possible, and avoid knee stiffness. Different internal fixators have their own biomechanical strengths and characteristics. The screw fixation has the advantage of being minimally invasive, but the fixation strength is limited, and it is mostly applied to Schatzker typeⅠfracture. For Schatzker Ⅰ-Ⅳ fracture, unilateral plate fixation can be used; for Schatzker Ⅴand Ⅵ fracture, bilateral plates fixation can be used to provide stronger fixation strength and avoid the stress concentration. The intramedullary nails fixation has the advantages of less trauma and less influence on the blood flow of the fracture end, but the fixation strength of the medial and lateral plateau is limited; so it is more suitable for tibial plateau fracture that involves only the metaphysis. Choosing the most appropriate internal fixation according to the patient’s condition is still a major difficulty in the surgical treatment of tibial plateau fractures. Conclusion Each internal fixator has good fixation effect on tibial plateau fracture within the applicable range, and it is an important research direction to improve and innovate the existing internal fixator from various aspects, such as manufacturing process, material, and morphology.
ObjectiveTo compare the biomechanical difference between petal-shaped poly-axial locking plate and tension band wire cerclage in fixing star-shaped 6-part patellar fractures in cadaver model, and provide the experimental data for clinical use.MethodsThe paired 12 knee specimens from 6 human cadavers were randomly divided into 2 groups (the control group and the test group) after a star-shaped 6-part patellar fracture model was established. The specimens were weighted, and the control group was fixed with tension band wire cerclage and the test group was fixed with petal-shaped poly-axial locking plate. The specimens were connected to CMT5105 biomechanics test machine by a customized fixture, the total fracture gap of patellar fracture blocks was measured before testing. The knee extensor load test was performed to record the extensor load of knees at 90° flexion to extension. Then the anti gravity physiological knee extension process at 90° flexion was stimulated according to the knee extensor load. The cyclic times until failure and the total fracture gap of patellar fracture blocks after failure were recorded.ResultsThe specimens weight and the total fracture gap of patellar fracture blocks before testing between 2 groups had no significant difference (t=0.410, P=0.690; t=0.650, P=0.530). In the biomechanical test, there was no significant difference of knee extension load between 2 groups (t=0.490, P=0.638). The total fracture gap after failure in test group was significantly smaller than that in control group (t=3.026, P=0.013), and the cyclic times until failure in test group was significantly more than that in control group (t=2.277, P=0.046). The failure reasons in control group were all the wires slipped off the Kirschner wires, while the failure reasons in test group were the screws pulled out from the upper pole in 5 cases (83.3%) and from the lower pole in 1 case (16.7%).ConclusionThe petal-shaped poly-axial locking plate has better biomechanical stiffness to fix the star-shaped 6-part patellar fractures when compared with tension band wire cerclage method. However, this type of fracture is a serious comminuted type, and the early excessive activity still carries the risk of displacement.
Objective
To evaluate the biomechanical property of tendons repaired with the modified Kessler suture combined with " 8” suture, and to provide evidence for the clinical application of this suture methods in repairing acute Achilles tendon rupture.
Methods
Forty frozen flexor digitorum longus tendons from fresh pork hind leg were randomly assigned into 4 groups, 10 specimens each group. In group A, the tendons were dissected transversely at the midpoint to forming the model of tendon with transversely cutting injury. The tendons in groups B, C, and D were dissected transversely at the midpoint, then a 2 cm segment of tendon from the incision in each side was dissected longitudinally with 1 mm internal to forming " frayed tendon” model. All the tendons were sutured with2-0 non-absorbable suture material with different suturing methods: in group A, the tendons with transversely cutting injury model with Krackow suture, and in the groups B, C, and D with Krackow suture, Kessler suture, and the modified Kessler suture combined with " 8” suture separately. All repaired tendons were fixed onto the biomechanical testing machine. The length, width, and thickness of each side and midpoint of the tendons were recorded, and the cross-sectional area was calculated. The tendons were stretched at a speed of 15 mm/minutes until failure (suture avulsion or rupture). The computer automatically recorded the maximum load, stress, strain, the failure displacement, and the stiffness. These biomechanical parameters of tendons in different groups were analyzed and compared.
Results
There was no significant difference in the length and cross-sectional area of each tendon among 4 groups (F=0.245, P=0.863; F=0.094, P=0.963). Two tendons in group B, 1 in group C, and 1 in group D were excluded because of tendon slipping; all tendons in group A and 8 tendons in group B failured due to suture rupture, 9 tendons in group C due to suture slipping, and 9 tendons in group D due to 3 sutures slipping from tendon tissue together. The maximum load, the maximum stress, the maximum strain, the failure displacement, and the stiffness of the tendons between groups A and B showed no significant difference (P>0.05). The maximum load, the maximum stress, and the stiffness of the tendons in group D were larger than those in both groups B and C (P<0.05), but no significant difference was found in the maximum strain and the failure displacement between groups B, C, and D (P>0.05). The maximum load, the maximum stress, the failure displacement, and the stiffness of the tendons in group B were larger than those in group C (P<0.05), but the difference of maximum strain between groups B and C was not significant (P>0.05).
Conclusion
The modified Kessler suture combined with " 8” suture can provide better biomechanical property of the repaired tendon compared with other suture approaches.
ObjectiveTo observe the changes in the biomechanical properties of the cornea of diabetic retinopathy (DR), and analyze its relationship with the degree of DR. MethodsA retrospective study. From September 2020 to February 2021, 83 patients with type 2 diabetes (T2DM) combined with DR treated in the Department of Ophthalmology, The First Affiliated Hospital of Zhengzhou University, 83 eyes (DR group), 30 patients with T2DM without DR recruited from the outpatient clinic 30 eyes (NDR group) and 30 eyes of non-diabetes patients (NDM group) were included in the study. All left eyes were chose as the study eye. Among the 83 eyes in the DR group, 39 eyes were non-proliferative DR (NPDR) and 44 eyes were proliferative DR (PDR). Based on this, they were divided into NPDR group and PDR group. There was no statistically significant difference in age (t=1.10) and sex ratio (χ2=0.46) among patients in the DR group, NDR group, and NDM group (P>0.05); body mass index (t=3.74), glycosylated hemoglobin (t=35.02) and the length of the eye axis (t=5.51), the difference was statistically significant (P<0.05). The eye response analyzer (ORA) was used to measure the corneal hysteresis (CH), corneal resistance factor (CRF), Goldman related intraocular pressure (IOPg), and corneal compensatory intraocular pressure (IOPcc). The corneal topography was used to measure the central corneal thickness (CCT) of the examined eye. The differences of CCT, IOPcc, IOPg, CH, CRF among multiple groups were compared by one-way analysis of variance. Multiple linear regression was used to analyze the relationship between CH, CRF and related influencing factors in DR patients. ResultsThere were statistically significant differences in CCT, IOPcc, IOPg, CH, and CRF among the eyes of the DR group, NDR group, and NDM group (F=3.71, 5.60, 9.72, 9.02, 21.97; P<0.05). Pairwise comparisons were between groups, CH, CRF: the difference between the DR group and the NDM group and the NDR group was statistically significant (P<0.05); CCT: the difference between the DR group and the NDM group was statistically significant (P<0.05), and The difference in the NDR group was not statistically significant (P>0.05). CCT, CH, CRF: the difference between the NDR group and the NDM group was not statistically significant (P>0.05). The results of multiple linear regression analysis showed that CCT and IOPcc in DR patients were independent influencing factors of CH [CCT: β=0.01, 95% confidence interval (CI) 0.01-0.03, P=0.013; IOPcc: β=－0.15, 95%CI －0.25-－0.05, P=0.005]; Age, CCT, IOPcc were independent influencing factors of CRF [Age: β=－0.06, 95%CI －0.09-－0.03, P＜0.001; CCT: β=0.01, 95%CI 0.00-0.02, P=0.049; IOPcc: β=0.16, 95%CI 0.07-0.25, P=0.001]. The comparison of CCT, CH, CRF, adjusted CH, and adjusted CRF of the eyes in the NDR group, NPDR group, and PDR group were statistically significant (F=3.76, 5.36, 12.61, 6.59, 10.41; P<0.05). Pairwise comparison between groups, CH, CRF, adjusted CH, adjusted CRF: the difference between the NPDR group, the PDR group and the NDR group was statistically significant (P<0.05), and the difference between the PDR group and the NPDR group was not statistically significant (P>0.05); CCT: The difference between NPDR group and NDR group, PDR group and NPDR group was not statistically significant (P>0.05), and the difference between PDR group and NDR group was statistically significant (P<0.05). ConclusionThe CH and CRF of eyes with T2DM and DR are elevated; CCT and IOPcc are independent influencing factors of CH, and age, CCT and IOPcc are independent influencing factors of CRF.
Objective To summarize the characteristics and biomechanical research progress of common acetabular reconstruction techniques in patients with Crowe type Ⅱ and Ⅲ developmental dysplasia of the hip (DDH) undergoing total hip arthroplasty (THA), and provide references for selecting appropriate acetabular reconstruction techniques for clinical treatment of Crowe type Ⅱ and Ⅲ DDH. Methods The domestic and foreign relevant literature on biomechanics of acetabular reconstruction with Crowe type Ⅱ and Ⅲ DDH was reviewed, and the research progress was summarized.Results At present, there are many acetabular reconstruction techniques in Crowe type Ⅱ and Ⅲ DDH patients undergoing THA, with their own characteristics due to structural and biomechanical differences. The acetabular roof reconstruction technique enables the acetabular cup prosthesis to obtain satisfactory initial stability, increases the acetabular bone reserve, and provides a bone mass basis for the possible secondary revision. The medial protrusio technique (MPT) reduces the stress in the weight-bearing area of the hip joint and the wear of the prosthesis, and increases the service life of the prosthesis. Small acetabulum cup technique enables shallow small acetabulum to match suitable acetabulum cup to obtain ideal cup coverage, but small acetabulum cup also increases the stress per unit area of acetabulum cup, which is not conducive to the long-term effectiveness. The rotation center up-shifting technique increases the initial stability of the cup. Conclusion Currently, there is no detailed standard guidance for the selection of acetabular reconstruction in THA with Crowe type Ⅱ and Ⅲ DDH, and the appropriate acetabular reconstruction technique should be selected according to the different types of DDH.
Atherosclerosis is a complex and multi-factorial pathophysiological process. Researches over the past decades have shown that the development of atherosclerotic vulnerable plaque is closely related to its components, morphology, and stress status. Biomechanical models have been developed by combining with medical imaging, biological experiments, and mechanical analysis, to study and analyze the biomechanical factors related to plaque vulnerability. Numerical simulation could quantify the dynamic changes of the microenvironment within the plaque, providing a method to represent the distribution of cellular and acellular components within the plaque microenvironment and to explore the interaction of lipid deposition, inflammation, angiogenesis, and other processes. Studying the pathological mechanism of plaque development would improve our understanding of cardiovascular disease and assist non-invasive inspection and early diagnosis of vulnerable plaques. The biomechanical models and numerical methods may serve as a theoretical support for designing and optimizing treatment strategies for vulnerable atherosclerosis.
Objective To improve the clinical utility of the plantaris tendon mainly by summarizing its anatomical characteristics, biomechanical properties, harvesting methods, and its applications in ligament reconstruction. Methods The relevant literature from domestic and international databases regarding the anatomical and biomechanical characteristics of the plantaris tendon and its applications in ligament reconstruction was comprehensively reviewed and systematically summarized. Results The plantaris tendons have an absence. The majority of plantaris tendon forms a fan-shape on the anterior and medial sides of the Achilles tendon and terminates at the calcaneal tuberosity. There are significant differences in biomechanical parameters between plantaris tendon with different numbers of strands, and multi strand plantaris tendon have significant advantages over single strand tendon. The plantaris tendon can be harvested through proximal and distal approaches, and it is necessary to ensure that there are no obvious anatomical variations or adhesions in the surrounding area before harvesting. The plantaris tendon is commonly utilized in ligament reconstruction around the ankle joint or suture reinforcement for Achilles tendon rupture, with satisfactory effectiveness. There is limited research on the use of plantar tendon in the reconstruction of upper limb and knee joint ligaments. Conclusion The plantaris tendon is relatively superficial, easy to be harvested, and has less impact on local function. The plantaris tendon is commonly utilized in ligaments reconstruction around the ankle joint or suture reinforcement for Achilles tendon rupture. The study on the plantaris tendon for upper limbs and knee joints ligament reconstruction is rarely and require further research.
Objective To establish a finite element model of the knee joint based on coronal plane alignment of the knee (CPAK) typing method, and analyze the biomechanical characteristics of different types of knee joints.Methods The finite element models of the knee joint were established based on CT scan data of 6 healthy volunteers. There were 5 males and 1 female with an average age of 24.2 years (range, 23-25 years). There were 3 left knees and 3 right knees. According to the CPAK typing method, the knees were rated as types Ⅰ to Ⅵ. Under the same material properties, boundary conditions, and axial loading, biomechanical simulations were performed on the finite element model of the knee joint. Based on the Von Mises stress nephogram and displacement nephogram, the peak stresses of the meniscus, femoral cartilage, and tibial cartilage, and the displacement of the meniscus were compared among different types of knee joints. Results The constructed finite element model of the knee joint was verified to be effective, and the stress and displacement results were consistent with previous literature. Under the axial load of 1 000 N, the stress nephogram showed that the stress distribution of the medial and lateral meniscus and tibial cartilage of CPAK type Ⅲ knee joint was the most uneven. The peak stresses of the lateral meniscus and tibial cartilage were 9.969 6 MPa and 2.602 7 MPa, which were 173% and 165% of the medial side, respectively. The difference of peak stress between the medial and lateral femoral cartilage was the largest in type Ⅳ knee joint, and the medial was 221% of the lateral. The displacement nephogram showed that the displacement of the medial meniscus was greater than that of the lateral meniscus except for types Ⅲ and Ⅵ knee joints. The difference between medial and lateral meniscus displacement of type Ⅲ knee joint was the largest, the lateral was 170% of the medial. Conclusion In the same type of joint line obliquity (JLO), the medial and lateral stress distribution of the knee was more uniform in varus and neutral positions than in valgus position. At the same time, the distal vertex of JLO subgroup can help to reduce the uneven medial and lateral stress distribution of varus knee, but increase the uneven distribution of valgus knee.
Objective
To study the biomechanical differences of the first carpometacarpal joint stability by using different reconstruction methods so as to provide theoretical basis for the clinical choice of reconstruction method.
Methods
The upper limb specimens were selected from 12 fresh adult cadavers, which had no fracture, bone disease, dislocation of wrist joint, deformity, degeneration, or ligament injury on the anteroposterior and lateral X-ray films. The specimens were randomly divided into 5 groups: normal group, injury group, palmar carpometacarpal ligaments reconstruction group, dorsal carpometacarpal ligaments reconstruction group, and palmar and dorsal carpometacarpal ligaments reconstruction group. Three normal specimens were used as normal group, and then were made of the first carpometacarpal joint dislocation models (injury group); after the first carpometacarpal joint dislocation was established in the other 9 specimens; the volar ligament, dorsal ligament, and volar-dorsal ligaments were reconstructed with Eaton-Little method, Yin Weitian method, and the above two methods in 3 construction groups. The biomechanical test was done to obtain the load-displacement curve and to calculate the elastic modulus.
Results
During biomechanical test, ligament rupture and loosening of Kirschner wire occurred in 1 case of injury group and palmar carpometacarpal ligaments reconstruction group; no slipping was observed. The elastic modulus values were (11.61±0.20), (5.39±0.12), (6.33±0.10), (7.12±0.08), and (8.30±0.10) MPa in normal group, injury group, palmar carpometacarpal ligaments reconstruction group, dorsal carpometacarpal ligaments reconstruction group, and palmar and dorsal carpometacarpal ligaments reconstruction group respectively, showing significant differences among groups (P<0.05).
Conclusion
Volar ligament reconstruction, dorsal ligament reconstruction, and volar-dorsal ligament reconstruction all can greatly improve the stability of the first carpometacarpal joint. And the effect of volar-dorsal ligament reconstruction is the best, but the stability can not restore to normal.
