Objective To simulate anterosuperior instabil ity of the shoulder by a combination of massive irreparable rotator cuff tears and coracoacromial arch disruption in cadaveric specimens, use proximally based conjoined tendon transfer forcoracoacromial l igament (CAL) reconstruction to restrain against superior humeral subluxation, and investigate its feasibility and biomechanics property. Methods Nine donated male-adult and fresh-frozen cadaveric glenohumeral joints were applied to mimic a massive irreparable rotator cuff tear in each shoulder. The integrity of the rotator cuff tendons and morphology of the CAL were visually inspected in the course of specimen preparation. Cal ipers were used to measure the length of the CAL’s length of the medial and the lateral bands, the width of coracoid process and the acromion attachment, and the thickness in the middle, as well as the length, width and thickness of the conjoined tendon and the lateral half of the removed conjoined tendon. The glenohumeral joints were positioned in a combination of 30° extension, 0° abduction and 30° external rotation. The value of anterosuperior humeral head translation was measured after the appl ication of a 50 N axial compressive load to the humeral shaft under 4 sequential scenarios: intact CAL, subperiosteal CAL release, CAL anatomic reattachment, entire CAL excision after lateral half of the proximally based conjoined tendon transfer for CAL reconstruction. Results All specimens had an intact rotator cuff on gross inspection. CAL morphology revealed 1 Y-shaped, 4 quadrangular, and 4 broad l igaments. The length of the medial and lateral bands of the CAL was (28.91 ± 5.56) mm and (31.90 ± 4.21) mm, respectively; the width of coracoid process and acromion attachment of the CAL was (26.80 ± 10.24) mm and (15.86 ± 2.28) mm, respectively; and the thickness of middle part of the CAL was (1.61 ± 0.36) mm. The length, width, and thickness of the proximal part of the proximally based conjoined tendon was (84.91 ± 9.42), (19.74 ± 1.77), and (2.09 ± 0.45) mm, respectively. The length and width of the removed lateral half of the proximally conjoined tendon was (42.67 ± 3.10) mm and (9.89 ± 0.93) mm, respectively. The anterosuperior humeral head translation was intact CAL (8.13 ± 1.99) mm, subperiosteal CAL release (9.68 ± 1.97) mm, CAL anatomic reattachment (8.57 ± 1.97) mm, and the lateral half of the proximally conjoined tendon transfer for CAL reconstruction (8.59 ± 2.06) mm. A significant increase in anterosuperior migration was found after subperiosteal CAL release was compared with intact CAL (P lt; 0.05). The translation after CAL anatomic reattachment and lateral half of the proximally conjoined tendon transfer for CAL reconstruction increased over intact CAL, though no significance was found (P gt; 0.05); when they were compared with subperiosteal CAL release, the migration decreased significantly (P lt; 0.05). The translation of lateral half of the proximally conjoined tendon transfer for CAL reconstruction increased over CAL anatomic reattachment, but no significance was evident (P gt; 0.05). Conclusion The CAL should be preserved or reconstructed as far as possible during subacromial decompression, rotator cuff tears repair, and hemiarthroplasty for patients with massive rotator cuff deficiency. If preservation or the insertion reattachment after subperiosteal release from acromion of the CAL of the CAL is impossible, or CAL is entirely resected becauseof previous operation, the use of the lateral half of the proximally based conjoined tendon transfer for CAL reconstruction isfeasible.
Objective To summarize the function of fibula in stability of ankle joints.Methods Recent original articles were extensively reviewed, which were related to the physiological function and biomechanical properties of fibula, the influence of fibular fracture on stability of ankle joints and mechanism of osteoarthritis of ankle joints. Results The fibula had the function of weightbearing; and it was generally agreed that discontinued fibula could lead to intra articular disorder of ankle joint in children; but there were various viewpoints regarding the influence of fibular fracture on the ankle joint in adults. Conclusion Fibula may play an important role in stability of ankle joint.
Objective To evaluate the biomechanical stability of a newly-designed Y type pedicle screw (YPS) in osteoporotic synthetic bone. Methods The osteoporotic synthetic bone were randomly divided into 3 groups (n=20). A pilot hole, 3.0 mm in diameter and 30.0 mm in deep, was prepared in these bones with the same method. The YPS, expansive pedicle screw (EPS), and bone cement-injectable cannulated pedicle screw (CICPS) were inserted into these synthetic bone through the pilot hole prepared. X-ray film examination was performed after 12 hours; the biomechanical stability of YPS, EPS, and CICPS groups was tested by the universal testing machine (E10000). The test items included the maximum axial pullout force, the maximum running torque, and the maximum periodical anti-bending. Results X-ray examination showed that in YPS group, the main screw and the core pin were wrapped around the polyurethane material, the core pin was formed from the lower 1/3 of the main screw and formed an angle of 15° with the main screw, and the lowest point of the inserted middle core pin was positioned at the same level with the main screw; in EPS group, the tip of EPS expanded markedly and formed a claw-like structure; in CICPS group, the bone cement was mainly distributed in the front of the screw and was dispersed in the trabecular bone to form a stable screw-bone cement-trabecular complex. The maximum axial pullout force of YPS, EPS, and CICPS groups was (98.43±8.26), (77.41±11.41), and (186.43±23.23) N, respectively; the maximum running torque was (1.42±0.33), (0.96±0.37), and (2.27±0.39) N/m, respectively; and the maximum periodical anti-bending was (67.49±3.02), (66.03±2.88), and (143.48±4.73) N, respectively. The above indexes in CICPS group were significantly higher than those in YPS group and EPS group (P<0.05); the maximum axial pullout force and the maximum running torque in YPS group were significantly higher than those in EPS group (P<0.05), but there was no significant difference in the maximum periodical anti-bending between YPS group and EPS group (P>0.05). Conclusion Compared with EPS, YPS can effectively enhance the maximum axial pullout force and maximum rotation force in the module, which provides a new idea for the design of screws and the choice of different fixation methods under the condition of osteoporosis.
【Abstract】 Objective To develop a new internal fixator Ni-Ti shape memory alloy scaphoid arc nail (NT-SAN)for fracture of the scaphoid waist and to test the biomechanical characteristics of NT-SAN so as to provide the biomechanicalproofs for cl inical appl ication. Methods According to the acquired measurements and anatomic features of the scaphoid in Chinese population, a special internal fixator—— NT-SAN was designed. The biomechanical intensity experiment: The 32 specimens of fractures of the waist of scaphoid were divided randomly into 4 groups (n =8). Reduction and internal fixation were carried out in each specimen, with Kirschner wires (Group A), with Kirschner wires stapl ing (Group B), with screw (Group C) and with NT-SAN (Group D). Their fixed strength was tested by a hydrol ic pressure biomechanical system AG-1. The biomechanical fatigue experiment: The models of 24 waist scaphoid fracture of adult upper l imbs specimens were made and randomly divided into 3 groups (n =8). Fracture was fixed with Kirschner wire stapl ing (Group E), with screw(Group F) and with NTSAN(Group G). Wrist joint was vertically pressured load of 98 N, palmar flexion and dorsal extension motion was simulated;the range of movement was from palmar flexion 5° to dorsal extension 30° and the frequency was 2 000 cycles. Displace data offragment were measured at every 500 cycles. Finally, the biomechanical features of NT-SAN were evaluated according to thetested data. NT-SAN was used to treated 1 patient with fracture of the waist of scaphoid, who was typed as Ⅱ b according to Herbert classification. Results The biomechanical tests showed that the traction forces were (15.18±3.55), (36.04±4.30),(64.88±11.62), (65.84±12.22) N and (20.28±12.09), (75.95±47.64), (120.91±26.68), (130.21±31.55) N when the displacements of the fracture l ines distracted in 1 mm/min were 1 mm and 2 mm; showing significant differences between Group D and groups A, B (P lt; 0.05), and showing no significant difference between Group D and Group C (P lt; 0.05). The biomechanical fatigue experiment showed that there were significant differences between Group G and groups E, F(P lt; 0.05) according to the measuredresults of the displacements of the fracture l ines. When wrist joint were circularly moved; showing significant differences between Group G and Group E(P lt; 0.05) after 500 circular movements, and showing significant differences between Group G and Group F(P lt; 0.05) after 1 500 circular movements according to the measured results of the “stage-shape” displacements in the fracture position. Incision healed by first intention and the X-ray films showed good NT-SAN fixation 3 months after followup.Conclusion The design of NT-SAN is in accordance with the anatomic features of the scaphoid. The fixed strength can meet the demand of the biomechanics and the range of fatigue strength can meet the demand of bony union.
One hundred and fifty cases were followed up after quadricepsplasty. Hamstring M. were used in 112 cases. M. rectus femoris or obliquis abdominis was used in 38 cases. The validity and force analysis of such two kinds of operation were analyzed and compared. It was confirmed that the power of the transferred muscle depended on the angle between the force line and the neutral axis of the joint, provided the arm of the force and the area of transection of the muscle were constant. The bigger the angle was, the longer the arm of the force was, and the smaller was the labour. If this angle was negative or the knee joint was in a position of flexion deformity, the smaller the negative angle was, the smaller the componend force of the joint was, and the larger was the component force of extension.
Objective To explore changes in the height and width of the cervical intervertebral foramina of C6,7 before and after the C5,6 discetomy, the replacement or the anterior intervertebral fusion so as to provide the theoretical basis for the clinical practice. Methods Eleven fresh cervical spinal specimenswere obtained from young adult cadavers. The specimens of C5,6 were divided into the integrity group, the discectomy group, the artificial disc replacement group, and the intervertebral fusion group. The range of variety (ROV) of the C6,7 intervertebral foramen dimensions (height, width) before and after the loading tests (0.75, 1.50 Nm) were measured in the 4 groups. Results The C6,7 intervetebral foramen height and width increased significantly during flexion (Plt;0.01) but decreased significantly during extension (Plt;0.01). There was a significantdifference between the two test conditions in each of the 4 groups (Plt;0.01). However, in the two test conditions there was no significant difference in ROV of the C6,7 intervetebral foramen height and width during flexion and extension betweenthe integrity group, the discectomy, and the artificial disc replacement group（Pgt;0.05）, but a significant difference in the above changes existed in the intervertebral fusion group when compared with the other 3 groups (Plt;0.05). In the same group and under the same conditions, the ROV of the C6,7 intervetebral foramen height and width was significantly different in the two test conditions (Plt;0.01). Conclusion The results have indicated thatartificial disc replacement can meet the requirements of the normal cervical vitodynamics. The adjacent inferior cervical intervetebral foramen increases during flexion but decreases during extension. The intervertebral fusion is probably one of the causes for the cervical degeneration or the accelerated degeneration and for the cervical spondylotic radiculopathy and the brachial plexus compression.
【Abstract】 Objective To determine the three-dimensional stabil ity of atlantoaxial reconstruction withanterior approach screw fixation through C2 vertebral body to C1 lateral mass and Gall ie’s technique (ASMG) for C1,2instabil ity. Methods Twenty-five human cadaveric specimens (C0-3 ) were divided randomly into 5 groups (n=5). Thethree-dimensional ranges of motion C1 relative to C2 were measured under the five different conditions：the intact state group (group A), type II odontoid fracture group (group B), posterior C1,2 transarticular screw fixation group (group C), ASM group (group D) and ASMG group (group E). The three-dimensional ranges of motions C1 relative to C2 by loading ± 1.5 Nm were measured under the six conditions of flexion/extension, left/right lateral bending, and left/right axial rotation. The obtained data was statistically analyzed. Results In each group, the three-dimensional ranges of motion C1 relative to C2 under the six conditions of flexion/extension, left/right lateral bending, and left/right axial rotation were as follows: in group A (8.10 ± 1.08), (8.49 ± 0.82), (4.79 ± 0.47), (4.93 ± 0.34), (28.20 ± 0.64), (29.30 ± 0.84)°; in group B (13.60 ± 1.25), (13.80 ± 0.77), (9.64 ± 0.53), (9.23 ± 0.41), (34.90 ± 0.93), (34.90 ± 1.30)°; in group C (1.62 ± 0.10), (1.90 ± 0.34), (1.25 ± 0.13), (1.37 ± 0.28), (0.97 ± 0.14), (1.01 ± 0.17)°; in group D (2.03 ± 0.26), (2.34 ± 0.49), (1.54 ± 0.22), (1.53 ± 0.30), (0.80 ± 0.35), (0.76 ± 0.30)°; in group E (0.35 ± 0.12), (0.56 ± 0.34), (0.44 ± 0.15), (0.55 ± 0.16), (0.43 ± 0.07), (0.29 ± 0.06)°. Under the six conditions, there were generally significant differences between group A and other four groups, and between group B and groups C, D and E (P lt; 0.001), and between group E and groups C, D in flexion/ extension and left/right lateral bending (P lt; 0.05). There was no significant difference between group E and groups C, D in left/right axial rotation (P gt; 0.05). Conclusion In vivo biomechanical studies show that ASMG operation has unique superiority in the reconstruction of the atlantoaxial stabil ity, especially in controll ing stabil ity of flexion/extension and left/right lateral bending, and thus it ensures successful fusion of the implanted bone. It is arel iable surgical choice for the treatment of the obsolete instabil ity or dislocation of C1, 2 joint.
Objective To explore the feasibility of using biomechanical indicators as supplementary evaluation to the Musculoskeletal Tumor Society Scoring System (MSTS) for amputee patients. Methods Twenty-four patients who underwent hemipelvectomy between September 2018 and January 2025 were enrolled. There were 15 males and 9 females with an average age of 61.4 years (range, 45-76 years). Participants performed gait tests at self-selected speeds using three assistive devices (prosthesis, single crutch, and double crutches). Motion data were analyzed using a customized OpenSim model. Biomechanical indicators of the intact limb exhibiting common characteristics were screened through correlation and sensitivity analyses. Test-retest reliability [interclass correlation coefficient (ICC)] of selected parameters was assessed to evaluate their potential as MSTS score supplements. Results All biomechanical indicators showed significant positive correlations with MSTS scores across assistive devices (P<0.05). Seven indicators demonstrated |Pearson correlation coefficients|>0.8, including walking speed, maximum hip angle, maximum hip moment, peak hip flexion moment, peak hip extension moment, hip flexion impulse, and hip extension impulse. Among these, maximum hip moment, hip flexion impulse, and hip extension impulse exhibited significant between-group differences in adjacent MSTS levels (P<0.05), indicating high sensitivity, along with excellent test-retest reliability (ICC>0.74, P<0.01). Conclusion Biomechanical indicators statistically qualify as potential supplements to MSTS scoring. Maximum hip moment, hip flexion impulse, and hip extension impulse demonstrate particularly high sensitivity to MSTS score variations.
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.
ObjectiveTo review the research progress on the lower limb biomechanical characteristics of patients with discoid lateral meniscus (DLM) injury after surgery. MethodsBy searching relevant domestic and international research literature on DLM, the postoperative characteristics of knee joint movement biomechanics, tibiofemoral joint stress distribution, lower extremity force line, and patellofemoral joint changes in patients with DLM injury were summarized. ResultsSurgical treatment can lead to varying degrees of changes in the lower limb biomechanical characteristics of patients with DLM injury. Specifically, the kinematic biomechanics of the knee joint can significantly improve, but there are still problems such as extension deficits in the affected knee joint. The peak stress of the tibiofemoral joint decreases with the increase of the residual meniscus volume, and the degree of change is closely related to the residual meniscus volume. Preserving a larger volume of the meniscus, especially the anterior horn volume, helps to reduce stress concentration. The lower extremity force line will deviate outward after surgery, and the more meniscus is removed during surgery, the greater the change in the lower extremity force line after surgery. There are conditions such as cartilage degeneration, position and angle changes in the patellofemoral joint after surgery. ConclusionThe changes in the lower limb biomechanical characteristics after DLM injury are closely related to the choice of surgical methods and rehabilitation programs. However, the mechanisms of biomechanical changes in multiple lower limb joints and individual differences still need to be further studied and clarified.