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    find Keyword "stability" 98 results
    • Biomechanical study of a newly-designed Y type pedicle screw in osteoporotic synthetic bone

      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.

      Release date:2017-10-10 03:58 Export PDF Favorites Scan
    • BIOMECHANICAL EVALUATION OF THE VALGUS STABILITY OF ELBOW AFTER RECONSTRUCTION

      Objective To evaluate of the valgus stability of the elbow after excision of the radial head, release of the medial collateral ligament (MCL), radial head replacement, and medial collateral ligament reconstruction.Methods Twelve fresh human cadaveric elbows were dissected to establish 7 kinds of specimens with elbow joint and ligaments as follow:①intact(n=12); ②release of the medial collateral ligament(n=6);③ excision of the radial head(n=6);④excision of the radial head together with release of the medial collateral ligament(n=12);⑤radial head replacement(n=6);⑥medial collateral ligament reconstruction(n=6);⑦radial head replacement together with medial collateral ligament reconstruction(n=12). Under two-newton-meter valgus torque, and at 0, 30, 60, 90 and 120 degrees of flexion with the forearm in supination, the valgus elbow laxity was quantified: All analysis was performed with SPSS 10.0 software.Results The least valgus laxity was seen in the intact state and its stability was the best. The laxity increased after resection of the radial head. The laxity was more after release of the medial collateral ligament than after resection of the radial head (Plt;0.01). The greatest laxity was observed after release of the medial collateral ligament together with resection of the radial head, so its stability was the worst. The laxity of the following implant of the radial head decreased. The laxity of the medial collateral ligament reconstruction was as much as that of the intact ligament (Pgt;0.05). The laxity of the radial head replacement together with medial collateral ligament reconstruction became less.Conclusion The results of this studyshow that the medial collateral ligament is the primary valgus stabilizer of the elbow and the radial head was a secondary constraint to resist valgus laxity.Both the medial collateral ligament reconstruction and the radial head replacement can restore the stability of elbow. If the radial head replacement can notbe carried out, the reconstruction of the medial collateral ligament is acceptable. 

      Release date:2016-09-01 09:29 Export PDF Favorites Scan
    • A study of the correlation between glenohumeral joint congruence and stability in recurrent shoulder dislocations

      ObjectiveTo investigate the correlation between glenohumeral joint congruence and stability in recurrent shoulder dislocations. Methods Eighty-nine patients (89 sides) with recurrent shoulder dislocation admitted between June 2022 and June 2023 and met the selection criteria were included as study subjects. There were 36 males and 53 females with an average age of 44 years (range, 20-79 years). There were 40 cases of left shoulder and 49 cases of right shoulder. The shoulder joints dislocated 2-6 times, with an average of 3 times. The three-dimensional models of the humeral head and scapular glenoid were reconstructed using Mimics 20.0 software based on CT scanning images. The glenoid track (GT), inclusion index, chimerism index, fit index, and Hill-Sachs interval (HSI) were measured, and the degree of on/off track was judged (K value, the difference between HSI and GT). Multiple linear regression was used to analyze the correlation between the degree of on/off track (K value) and inclusion index, chimerism index, and fit index. ResultsMultiple linear regression analysis showed that the K value had no correlation with the inclusion index (P>0.05), and was positively correlated with the chimerism index and the fit index (P<0.05). Regression equation was K=–24.898+35.982×inclusion index+8.280×fit index, R2=0.084. ConclusionHumeral head and scapular glenoid bony area and curvature are associated with shoulder joint stability in recurrent shoulder dislocations. Increased humeral head bony area, decreased scapular glenoid bony area, increased humeral head curvature, and decreased scapular glenoid curvature are risk factors for glenohumeral joint stability.

      Release date:2023-09-07 04:22 Export PDF Favorites Scan
    • REPAIR OF OLD INJURY OF KNEE MEDIAL COLLATERAL LIGAMENT BY A COMBINATION OF DYNAMIC AND STATIC STABILITY

      Objective To observe the effectiveness of the combination of dynamic and static stabil ity in the treatment of old knee medial collateral l igament injury. Methods Between March 2004 and June 2008, 26 cases of old knee medial collateral l igament injury were treated, including 19 males and 7 females with a mean age of 38 years (range, 21-48 years). Injury was caused by traffic accident in 6 cases, by sprains in 12 cases, by fall ing from height in 8 cases. The location was left knee in 15 cases and right knee in 11 cases. Of them, 24 patients showed the positive result of knee valgus test, 2 cases showed sl ightly relaxed knee tendon. The knee X-ray films of valgus stress position showed that the medial joint space differences between both knees were 3-5 mm in 2 cases and 5-12 mm in 24 cases. The injuries included avulsion of the medial femoral condyle starting point in 19 cases, central laceration in 6 cases, and tibial point laceration concomitant meniscus injury in 1 case. The time from injury to hospital ization was 3-14 months (mean, 6.4 months). Gracil is muscle was used to repair knee medial collateral l igament and the sartorius muscle transfer to reconstruct the medial rotation of knee stabil ity function. Results All incisions healed by first intention. No joint infection, deep vein thrombosis, or other postoperative compl ications occurred. Twentysix cases were followed up 12-58 months with an average of 30 months. The results of knee valgus stress test were negative with no joint tenderness. At 3 months after operation, the knee X-ray films of valgus stress position showed the medial joint space differences between both knees were less than 1 mm. According to the modified Lysholm-Scale score, the results were excellent in 18 cases, good in 7 cases, and fair in 1 case with an excellent and good rate of 96% at last follow-up. Conclusion A combination of dynamic and static stabil ity in repairing old knee medial collateral l igament injury is easy-to-operate and has the advantages to perform the operation in the same incision, so it can avoid the shortcomings of single repair method and achieve better effectiveness.

      Release date:2016-08-31 05:41 Export PDF Favorites Scan
    • BIOMECHANICAL STUDY ON PROXIMALLY BASED CONJOINED TENDON TRANSFER FOR CORACOACROMIAL LIGAMENT RECONSTRUCTION AS ANTEROSUPERIOR RESTRAINT OF SHOULDER JOINT

      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.

      Release date:2016-09-01 09:08 Export PDF Favorites Scan
    • RESEARCH PROGRESS OF BIOMECHANICS OF PROXIMAL ROW CARPAL INSTABILITY

      ObjectiveTo review the research progress of the biomechanics of proximal row carpal instability (IPRC). MethodsThe related literature concerning IPRC was extensively reviewed. The biomechanical mechanism of the surrounding soft tissue in maintaining the stability of the proximal row carpal (PRC) was analyzed, and the methods to repair or reconstruct the stability and function of the PRC were summarized from two aspects including basic biomechanics and clinical biomechanics. ResultsThe muscles and ligaments of the PRC are critical to its stability. Most scholars have reached a consensus about biomechanical mechanism of the PRC, but there are still controversial conclusions on the biomechanics mechanism of the surrounding soft tissue to stability of distal radioulnar joint when the triangular fibrocartilage complex are damaged and the biomechanics mechanism of the scapholunate ligament. At present, there is no unified standard about the methods to repair or reconstruct the stability and function of the PRC. So, it is difficult for clinical practice. ConclusionSome strides have been made in the basic biomechanical study on muscle and ligament and clinical biomechanical study on the methods to repair or reconstruct the stability and function of PRC, but it will be needed to further study the morphology of carpal articular surface and the adjacent articular surface, the pressure of distal carpals to proximal carpal and so on.

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    • Research on Adaptive Balance Reaction for Gait Slippery Instability Events on Level Walk Based on Plantar Pressure and Gait Parameter Analysis

      Nowadays, for gait instability phenomenon, many researches have been carried out at home and abroad. However, the relationship between plantar pressure and gait parameters in the process of balance adjustment is still unclear. This study describes the human body adaptive balance reaction during slip events on slippery level walk by plantar pressure and gait analysis. Ten healthy male subjects walked on a level path wearing shoes with two contrastive contaminants (dry, oil). The study collected and analyzed the change rule of spatiotemporal parameters, plantar pressure parameters, vertical ground reaction force (VGRF), etc. The results showed that the human body adaptive balance reaction during slip events on slippery level walk mainly included lighter touch at the heel strikes, tighter grip at the toe offs, a lower velocity, a shorter stride length and longer support time. These changes are used to maintain or recover body balance. These results would be able to explore new ideas and provide reference value for slip injury prevention, walking rehabilitation training design, research and development of walking assistive equipments, etc.

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    • Status of programmed death-1 / programmed death-ligand 1 inhibitors in combination with vascular endothelial growth factor / vascular endothelial growth factor receptor inhibitors in advanced refractory colorectal cancer

      ObjectiveTo analyze the status of applying programmed death-1 (PD-1) / programmed death-ligand 1 (PD-L1) inhibitors combined with vascular endothelial growth factor (VEGF) / vascular endothelial growth factor receptor (VEGFR) inhibitors in advanced refractory colorectal cancer. MethodThe relevant literature on domestic and foreign research in recent years was summarized. ResultsThe discovery of immune checkpoint PD-1/PD-L1 and the clinical application of related drugs had changed the treatment pattern of advanced solid tumors, but PD-1/PD-L1 inhibitors had a poor efficacy in the mismatch repair prodicient tumors, and most advanced colorectal cancer belonged to this type. The combination of PD-1/PD-L1 inhibitors and VEGF/VEGFR inhibitors could enhance the therapeutic effect in the advanced refractory colorectal cancer, and their interaction mechanisms and clinical efficacy were continuously being proven. ConclusionsThe combination of PD-1/PD-L1 inhibitors and VEGF/VEGFR inhibitors is a promising treatment strategy for advanced refractory colorectal cancer. More studies need to be further clarified its efficacy.

      Release date:2024-08-30 06:05 Export PDF Favorites Scan
    • TREATMENT OF SEVERE MEDIAL COLLATERAL LIGAMENT RUPTURE IN MULTI-LIGAMENT INJURY

      ObjectiveTo compare the clinical efficacy between medial collateral ligament (MCL) repair and MCL reconstruction in multi-ligament injury. MethodsThirty-one patients with MCL rupture and multi-ligament injury of knee joint were treated between August 2008 and August 2012, and the clinical data were retrospectively analyzed. Of 31 patients, 11 cases underwent MCL repair (repair group), and 20 cases underwent MCL reconstruction (reconstruction group). There was no significant difference in gender, age, body mass, injury side, injury cause, and preoperative knee Lyshlom score, International Knee Documentation Committee (IKDC) subjective score, range of motion, and medial joint opening between 2 groups (P > 0.05). The postoperative knee subjective function and stability were compared between 2 groups. ResultsAll incisions healed by first intention, and no postoperative complication occurred. All patients were followed up 2-4 years (mean, 3.2 years). At 2 years after operation, the IKDC subjective score, Lyshlom score, and range of motion were significantly increased in 2 groups when compared with preoperative ones (P < 0.05). The range of motion of reconstruction group was significantly better than that of repair group (P < 0.05). No significant difference was found in IKDC subjective score and Lyshlom score between 2 groups (P > 0.05). The medial joint opening was significantly improved in 2 groups at 2 years after operation when compared with preoperative one (P < 0.05), but no significant difference was found between 2 groups (P > 0.05). ConclusionBoth the MCL reconstruction and MCL repair can restore medial stability in multi-ligament injury, but MCL reconstruction is better than MCL repair in range of motion.

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    • Experience in diagnosis and treatment of KD-ⅢM dislocation of knee joint

      ObjectiveTo explore the effectiveness of one-stage posterior medial corner (PMC) repair or reconstruction combined with anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) reconstruction in treating KD-ⅢM dislocation. Methods The clinical data of 15 patients with knee KD-ⅢM dislocation who met the selection criteria between January 2016 and July 2019 were retrospectively analyzed. There were 9 males and 6 females, aged 22-61 years (mean, 40.3 years). Injuries were caused by violence of flexion, valgus, and external rotation, including 10 cases of traffic accident injuries, 3 cases of crush injuries, 1 case of winch injury, and 1 case of explosion injury. The time from injury to operation ranged from 3 days to 6 months, with an average of 18.5 days. PMC repair combined with PCL+ACL reconstruction was performed in 10 cases in acute stage (within 3 weeks after injury), including 3 cases of irreducible dislocation. PMC+PCL+ACL reconstruction was performed in 5 cases with chronic dislocation. Before operation and at last follow-up, the knee joint function was evaluated by Lysholm score and International Knee Documentation Committee (IKDC) 2000 score. KT-3000 was used to evaluate the forward stability of the knee (calculated the difference of tibial anterior displacement of both knees), the X-ray films of the stress position of the knee joint was used to evaluate the valgus of the knee (calculated the difference of medial joint space width of both knees) and the backward stability (calculated the difference of tibial posterior displacement of both knees), and the internal and external rotation stability was evaluated by knee flexion 30° tibial external rotation and knee flexion 90° tibial internal rotation tests (calculated the difference of tibial internal rotation and the difference of tibial external rotation of both knees). Results The operation time was 120-240 minutes, with an average of 186.5 minutes. Patients were followed up 24-48 months, with an average of 27.4 months. There was no complication such as infection, deep vein thrombosis, vascular injury, or heterotopic ossification. At last follow-up, the Lysholm score, IKDC2000 score, the difference of tibial anterior displacement of both knees, the difference of medial joint space width of both knees, the difference of tibial posterior displacement of both knees, the difference of tibial internal rotation and the difference of tibial external rotation of both knees significantly improved when compared with preoperative ones (P<0.05). According to the IKDC2000 valgus stability grading standard, there were 3 cases of grade C and 12 cases of grade D before operation, and 10 cases of grade A and 5 cases of grade B at last follow-up, which was significantly improved when compared with that before operation (Z=?4.930, P=0.000). At last follow-up, the pivot shift tests of 15 patients were negative. The anterior and posterior drawer tests of 10 patients were negative, 5 patients had mild instability, both the anterior and posterior drawer tests were positive. ConclusionKD-ⅢM dislocation of the knee joint can lead to the posterior medial and anterior instability. Acute dislocation combined with “dimple sign” requires surgical reduction as soon as possible to repair PMC and reconstruct PCL and ACL. In chronic patients, PMC is difficult to repair, it is recommended to reconstruct PMC, PCL, and ACL at one stage to improve knee joint stability. The early and middle effectiveness are satisfactory.

      Release date:2022-01-27 11:02 Export PDF Favorites Scan
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  • 松坂南