ObjectiveTo compare the strength difference between the interfacial screw and the interfacial screw combined with bone tunnel crossing technology to fix the tibial end of ligament during anterior cruciate ligament (ACL) reconstruction through the biomechanical test.MethodsTwenty fresh frozen pig tibia were randomly divided into two groups (n=10) to prepare ACL reconstruction models. The graft tendons in the experimental group were fixed with interfacial screw combined with bone tunnel crossing technology, and the graft tendons in the control group were fixed with interfacial screw. The two groups of specimens were fixed in the high-frequency dynamic mechanics test system M-3000, and the length change (displacement), ultimate load, and stiffness of graft tendons were measured through the reciprocating test and load-failure test.ResultsThe results of reciprocating test showed that the displacement of the experimental group was (3.06±0.58) mm, and that of the control group was (2.82±0.46) mm, and there was no significant difference between the two groups (t=0.641, P=0.529). The load-failure test results showed that the stiffness of the experimental group and the control group were (95.39±13.63) and (91.38±14.28) N/mm, respectively, with no significant difference (t=1.021, P=0.321). The ultimate load of the experimental group was (743.15±173.96) N, which was significantly higher than that of the control group (574.70±74.43) N (t=2.648, P=0.016).ConclusionIn ACL reconstruction, the fixation strength of tibial end with interface screw combined with bone tunnel crossing technology is obviously better than that of interface screw alone.
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.
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 discuss the role of the bone suture anchors for repair of avulsed deep radioulnar ligaments in maintaining the rotatory stability of the distal radioulnar joint. Methods Nine upper limbs specimens were selected from fresh adult cadavers to make wrist joint-bone capsular ligaments complex specimen. All the specimens were tested under conditions of intact (normal group), deep radioulnar ligaments injury (injury group), and deep radioulnar ligaments injury repaired with anchoring (repair group). The internal and external rotation torque values were recorded in 45° wrist extension, neutral position, and 45° wrist flexion by AG-IS series MS biomechanical testing system. The statistic software was used to compare difference in rotation torque between groups. Results In 45° wrist extension, neutral position, and 45° wrist flexion, the internal rotation torque values in normal group were (0.83±0.33), (0.86±0.34), and (0.36±0.30) N·m respectively; the external rotation torque values were (0.86±0.38), (0.44±0.22), and (0.25±0.21) N·m respectively. The internal rotation torque values in injury group were (0.18±0.17), (0.22±0.17), and (0.16±0.15) N·m respectively; the external rotation torque values were (0.27±0.26), (0.13±0.17), and (0.04±0.04) N·m respectively. The internal rotation torque values in repair group were (0.79±0.34), (0.73±0.33), and (0.41±0.23) N·m respectively; the external rotation torque values were (0.80±0.39), (0.41±0.22), (0.41±0.40) N·m respectively. In 45° wrist extension, neutral position, and 45° wrist flexion, the internal and external rotation torque values in injury group were significantly lower than those in normal group and repair group (P<0.05), but no significant difference was found between repair group and normal group (P>0.05). Conclusion The deep radioulnar ligaments are important structure for maintaining rotatory stability of distal radioulnar joint. Bone anchoring of the avulsed deep radioulnar ligaments to the ulna fovea is critically important in reconstructing function anatomy of the distal radioulnar joint.
Objective To investigate the effects of percutaneous cement discoplasty (PCD) and percutaneous cement interbody fusion (PCIF) on spinal stability by in vitro biomechanical tests. Methods Biomechanical test was divided into intact (INT) group, percutaneous lumbar discectomy (PLD) group, PCD group, and PCIF group. Six specimens of L4, 5 (including vertebral bodies and intervertebral discs) from fresh male cadavers were taken to prepare PLD, PCD, and PCIF specimens, respectively. Before treatment and after the above treatments, the MTS multi-degree-of-freedom simulation test system was used to conduct the biomechanical test. The intervertebral height of the specimen was measured before and after the axial loading of 300 N, and the difference was calculated. The range of motion (ROM) and stiffness of the spine in flexion, extension, left/right bending, and left/right rotation under a torque of 7.5 Nm were calculated. Results After axial loading, the change of intervertebral height in PLD group was more significant than that in other three groups (P<0.05). Compared with INT group, the ROM in all directions significantly increased and the stiffness significantly decreased in PLD group (P<0.05). Compared with INT group, the ROM of flexion, extension, and left/right rotation in PCD group significantly increased and the stiffness significantly decreased (P<0.05); compared with PLD group, the ROM of flexion, extension, and left/right bending in PCD group significantly decreased and the stiffness significantly increased (P<0.05). Compared with INT group, ROM of left/right bending in PCIF group significantly decreased and stiffness significantly increased (P<0.05); compared with PLD group, the ROM in all directions significantly decreased and the stiffness significantly increased (P<0.05); compared with PCD group, the ROM of flexion, left/right bending, and left/right rotation significantly decreased and stiffness significantly increased (P<0.05). Conclusion Both PCD and PCIF can provide good biomechanical stability. The former mainly affects the stiffness in flexion, extension, and bending, while the latter is more restrictive on lumbar ROM in all directions, especially in bending and rotation.
Objective To analyze the biomechanical changes of hallux valus after Swanson prosthesis-arthroplasty of the 1st metatarsophalangeal joint combined with osteotomy and bone grafting of the 1st metatarsal bone by three-dimensional finite element analysis, so as to provide data basis for studying the changes of foot morphology and physiological function after hallux valus correction surgery. Methods A 65-year-old female patient with severe hallux valus admitted in January 2013 was selected as the research object. The CT data of the right foot was obtained, and the three-dimensional finite element models before and after Swanson prosthesis-arthroplasty of the 1st metatarsophalangeal joint combined with osteotomy and bone grafting of the 1st metatarsal bone were established by Mimics10.01, Geomagic Studio, and ANSYS12.0 software. ANSYS 12.0 software was used for nonlinear static stress analysis, and the hallux valgus angle (HVA), the intermetatarsal angle (IMA), and the von Mises stress distributions of the forefoot plantar surface and the 1st to 5th metatarsal bones were observed before and after operation. ResultsThe HVA and IMA were 56.3° and 16.3° before operation and 9.2° and 9.8° after operation, respectively. Before operation, the stress on the forefoot was the largest in the 4th metatarsal head zone and the smallest in the 1st metatarsal head zone; the stress on the medial side of the forefoot was significantly smaller than that on the lateral side, and the center of forefoot pressure was located on the lateral side. After operation, the stress on the forefoot was the largest in the 1st metatarsal head zone and the smallest in the 5th metatarsal head zone; the stress on the lateral side of the forefoot was significantly smaller than that on the medial side, and the center of forefoot pressure was located on the medial side. Before operation, the stress of the 5th metatarsal bone was the largest, and the 1st metatarsal bone was the smallest. After operation, the stress of the 1st metatarsal bone was the largest, and the 4th metatarsal bone was the smallest. Conclusion Swanson prosthesis-arthroplasty of the 1st metatarsophalangeal joint combined with osteotomy and bone grafting of the 1st metatarsal bone can effectively correct hallux valgus and make HVA, IMA, and plantar pressure distribution close to normal. However, postoperative stresses of the 1st to 5th metatarsal bones elevate, which may lead to associated complications.
A comprehensive, geometrically accurate, nonlinear C0-T1 three-dimensional finite element (FE) model was developed for the biomechanical study of human cervical spine and related disorders. The model was developed with anatomic detail from the computed tomography (CT) images of a 46-year old female healthy volunteer, and applied the finite element model processing softwares such as MIMICS13.1, Hypermesh11.0, Abaqus 6.12-1, etc., for developing, preprocessing, calculating and analysing sequentially. The stress concentration region and the range of motion (ROM) of each vertebral level under axial rotation, flexion, extension, and lateral bending under physiologic static loadings were observed and recorded. The model was proven reliable, which was validated with the range of motion in previous published literatures. The model predicted the front and side parts of the foramen magnum and contralateral pedicle and facet was the stress concentration region under physiological loads of the upper spine and the lower spine, respectively. The development of this comprehensive, geometrically accurate, nonlinear cervical spine FE model could provide an ideal platform for theoretical biomechanical study of human cervical spine and related disorders.
ObjectiveTo evaluate the biomechanical effect of a nickel-titanium (Ni-Ti) three-dimensional memory alloy mesh in treating a canine tibial plateau collapse fracture model and to lay a foundation for further experiments in vivo.MethodsSixteen tibial plateau specimens of 8 adult Beagle dogs were harvested. Twelve specimens were taken to prepare canine tibial plateau collapse fracture models (Schatzker type Ⅲ) and randomly divided into groups A, B, and C, with 4 specimens in each group. Four normal tibia specimens were used as blank control group (group D). In groups A and B, the bone defects were repaired with Ni-Ti three-dimensional shape memory alloy mesh combined with autologous bone and simple autologous bone respectively, and fixed with the lateral plate and screw. In group C, the bone defect was directly fixed with the lateral plate and screw. By using a biomechanical tester, a progressive load (0-1 700 N) was loaded vertically above the femoral condyle. The maximum failure load was recorded and the stiffness was calculated according to the load-displacement curve.ResultsThe maximum failure loads in groups A, B, C, and D were (1 624.72±7.02), (1 506.57±3.37), (1 102.00±1.83), and (1 767.64±24.56) N, respectively; and the stiffnesses were (129.72±20.83), (96.54±27.05), (74.96±17.70), and (169.01±35.62) N/mm, respectively. The maximum failure load and stiffness in group A were significantly higher than those in groups B and C, but which were significantly lower than those in group D (P<0.05).ConclusionNi-Ti three-dimensional memory alloy mesh combined with autologous bone can repair the Schatzker type Ⅲ tibial plateau collapse fracture, which has better biomechanical properties than simple autologous bone grafting.
ObjectiveTo review the research progress of the biomechanical study of the Bristow-Latarjet procedure for anterior shoulder dislocation. MethodsThe related biomechanical literature of Bristow-Latarjet procedure for anterior shoulder dislocation was extensively reviewed and summarized. ResultsThe current literature suggests that when performing Bristow-Latarjet procedure, care should be taken to fix the bone block edge flush with the glenoid in the sagittal plane in the direction where the rupture of the joint capsule occurs. If traditional screw fixation is used, a double-cortical screw fixation should be applied, while details such as screw material have less influence on the biomechanical characteristics. Cortical button fixation is slightly inferior to screws in terms of biomechanical performance. The most frequent site of postoperative bone resorption is the proximal-medial part of the bone block, and the cause of bone resorption at this site may be related to the stress shielding caused by the screw. ConclusionThere is no detailed standardized guidance for bone block fixation. The optimal clinical treatment plan for different degrees of injury, the factors influencing postoperative bone healing and remodeling, and the postoperative osteoarticular surface pressure still need to be further clarified by high-quality biomechanical studies.
Objective To design customized titanium alloy lunate prosthesis, construct three-dimensional finite element model of wrist joint before and after replacement by finite element analysis, and observe the biomechanical changes of wrist joint after replacement, providing biomechanical basis for clinical application of prosthesis. Methods One fresh frozen human forearm was collected, and the maximum range of motions in flexion, extension, ulnar deviation, and radialis deviation tested by cortex motion capture system were 48.42°, 38.04°, 35.68°, and 26.41°, respectively. The wrist joint data was obtained by CT scan and imported into Mimics21.0 software and Magics21.0 software to construct a wrist joint three-dimensional model and design customized titanium alloy lunate prosthesis. Then Geomagic Studio 2017 software and Solidworks 2017 software were used to construct the three-dimensional finite element models of a normal wrist joint (normal model) and a wrist joint with lunate prosthesis after replacement (replacement model). The stress distribution and deformation of the wrist joint before and after replacement were analyzed for flexion at and 15°, 30°, 48.42°, extension at 15°, 30°, and 38.04°, ulnar deviation at 10°, 20°, and 35.68°, and radial deviation at 5°, 15°, and 26.41° by the ANSYS 17.0 finite element analysis software. And the stress distribution of lunate bone and lunate prosthesis were also observed. Results The three-dimensional finite element models of wrist joint before and after replacement were successfully constructed. At different range of motion of flexion, extension, ulnar deviation, and radial deviation, there were some differences in the number of nodes and units in the grid models. In the four directions of flexion, extension, ulnar deviation, and radial deviation, the maximum deformation of wrist joint in normal model and replacement model occurred in the radial side, and the values increased gradually with the increase of the range of motion. The maximum stress of the wrist joint increased gradually with the increase of the range of motion, and at maximum range of motion, the stress was concentrated on the proximal radius, showing an overall trend of moving from the radial wrist to the proximal radius. The maximum stress of normal lunate bone increased gradually with the increase of range of motion in different directions, and the stress position also changed. The maximum stress of lunate prosthesis was concentrated on the ulnar side of the prosthesis, which increased gradually with the increase of the range of motion in flexion, and decreased gradually with the increase of the range of motion in extension, ulnar deviation, and radialis deviation. The stress on prosthesis increased significantly when compared with that on normal lunate bone. Conclusion The customized titanium alloy lunate prosthesis does not change the wrist joint load transfer mode, which provided data support for the clinical application of the prosthesis.