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.
ObjectiveTo summarize the progress in treatment of unstable atlas fracture, the existing problems, and the research direction.MethodsRelated literature at home and abroad was reviewed. The stability evaluation of atlas fracture and treatment methods were introduced, and the selection of surgical approach and fixation instruments in treatment of unstable atlas fracture were summarized and analyzed.ResultsAt present, atlas fractures are considered as unstable fractures except single anterior arch fractures with complete transverse ligament or simple posterior arch fractures. The treatment of unstable atlas fracture has been developed from nonsurgical treatment and traditional fusion surgery to single-segment fixation. Nonsurgical treatment is less effective, while traditional fusion surgery has a disadvantage of limited the motion of the upper cervical spine. Single-segment fixation can not only restore and fix the fracture, but also preserve the upper cervical motion function. Single-segment fixation approaches include posterior and transoral approaches, and the fixation instruments are being constantly improved, mainly including screw-rod system, screw-plate system, and plate system.ConclusionFor unstable atlas fracture, single-segment fixation is an ideal surgical method, and has more advantages when compared with nonsurgical treatment and traditional fusion surgery. Single-segment fixation via transoral approach is more direct for atlas anterior arch fracture reduction, but there is a high risk of infection; and single-segment fixation via posterior approach is less effective for the reduction of atlas anterior arch fracture. Therefore, a better reduction method should be explored.
Objective To summarize the current research progress of second sacral alar-iliac (S2AI) screw technique for reconstruction of spinopelvic stability. Methods The recent original literature concerning development, clinical applications, anatomy, imageology, and biomechanics of S2AI screw technique in reconstruction of spinopelvic stability was reviewed and analyzed. Results As a common clinical strategy for the reconstruction of spinopelvic stability, S2AI screws achieve satisfactory effectiveness of lumbosacral fixation without complications which were found during the application of traditional iliac screws technique. S2AI screw technique is more difficult to place screws by hand because of its narrow screw trajectory. Although the S2AI screws trajectory pass through 3 layers of bone cortex, the biomechanical cadaveric study demonstrate that no statistical difference in stiffness was found between the traditional iliac and S2AI screw in a spinopelvic fixation model. Conclusion S2AI screw technique should be a safe and feasible method for reconstruction of spinopelvic stability in place of the traditional iliac screw technique.
ObjectiveTo understand the cervical spine function, core stability and strength of fighter pilots, and to explore the difference of that between fighter pilots with and without neck pain.MethodsFrom October to December 2020, a double-blind design was used to test the cervical spine function, core stability and strength of fighter pilots of a certain part of the Air Force. At the same time, the area of deep cervical flexor and the thickness of transverse abdominis and multifidus muscles were measured. According to the presence or absence of neck pain in the last 3 months, they were divided into neck pain group and non-neck pain group. The cervical spine function, core stability and core strength, deep cervical flexor and transversus abdominis endurance of the two groups were compared and analyzed.ResultsA total of 38 pilots were included. There was no significant difference in age, body mass index, service life, flight time, total flight time and weekly flight time between the neck pain group and the non-neck pain group (P>0.05). There was no significant difference in cervical spine mobility between the two groups of pilots (P>0.05). The cervical flexor muscle strength [(15.5±4.9) vs. (12.1±3.0) N] and the ratio of cervical flexion/neck extension (0.6±0.1 vs. 0.5±0.1) in the non-neck pain group were higher than in the neck pain group (P<0.05). There was no significant difference in the muscle strength of other superficial cervical muscles between the two groups (P>0.05). The average value of deep neck flexor endurance in the neck pain group [25.36 mm Hg(1 mm Hg=0.133 kPa)] better than the non-neck pain group group (17.11 mm Hg) (P=0.026). There was no significant difference in test values of transverse abdominis endurance between the two groups (P>0.05). The left hip internal rotator strength [(11.9±2.6) vs. (10.0±2.1) N] and the left hip external rotator strength [(13.7±2.2) vs. (11.9±2.0) N] in the non-neck pain group were higher than in the neck pain group (P<0.05). There was no significant difference in the muscle strength of the other hip joint muscles between the two groups (P>0.05). The thickness of the right transversus abdominis in the neck pain group [(1.1±0.3) vs. (0.8±0.3) cm] was higher than that in the non-neck pain group (P<0.05). There was no significant difference in the thickness of the left transversus abdominis, the cross-sectional area of deep cervical flexor muscle and the thickness of lumbar multifidus muscle between the two groups (P>0.05).ConclusionsFighter pilots with neck pain have superficial cervical flexor muscle strength and decreased left hip internal and external rotation muscle strength, and the superficial cervical flexor and extensor muscle strength is unbalanced. Strengthening the superficial cervical flexor muscle strength, improving the balance between the superficial cervical flexor and extensor muscles, and enhancing the hip internal and external rotator muscle strength may help prevent neck pain.
Objective To evaluate the effectiveness of unstable femoral neck fracture with posteromedial comminutations treated by cannulated screws and medial bracing plate combined with bone allograft. MethodsThe clinical data of 18 patients with unstable femoral neck fracture with posteromedial comminutations treated by cannulated screws and medial bracing plate combined with bone allograft between July 2016 and March 2020 were retrospectively analyzed. The age ranged from 22 to 64 years, with a median age of 43 years. The causes of injury included 11 cases of falling injury, 3 cases of traffic accident injury, and 4 cases of fall from height injury. According to Garden classification, the femoral neck fracture was classified as type Ⅲ in 3 cases, type Ⅳ in 15 cases, and all patients were type Ⅲ according to Pauwels classification. The time from injury to operation was 1-5 days, with an average of 2.3 days. The fracture healing time and complications were recorded. The quality of fracture reduction was evaluated by Garden index immediately after operation; at last follow-up, the degree of femoral neck shortening was determined by Zlowodzki method, Harris score was used to evaluate hip function. Results The operation time was 62-98 minutes (mean, 75 minutes); intraoperative blood loss was 101-220 mL (mean, 153 mL). Cannulated screws guide wire was inserted 3-5 times (mean, 4 times). Intraoperative fluoroscopy was performed 9-21 times (mean, 15 times). The hospital stay was 5-11 days (mean, 7.2 days). All the patients were followed up 12-40 months with an average of 17.3 months. There was no postoperative complication such as accumulated pneumonia, lower extremity deep venous thrombosis, nail cutting, nail withdrawal, internal fixation fracture, and so on. There was no fracture nonunion and osteonecrosis of the femoral head during the follow-up; the fracture healing time was 7-15 weeks, with an average of 12.1 weeks. The quality of fracture reduction was evaluated immediately after operation, the results were grade Ⅰ in 15 cases and grade Ⅱ in 3 cases. At last follow-up, there were 2 cases with femoral neck shortening less than 5 mm and 1 case with 5-10 mm. The incidence of femoral neck shortening was 16.7%. The Harris score of hip joint was 73-97, with an average of 93.5; among them, 12 cases were rated as excellent, 3 cases as good, and 3 cases as fair, with an excellent and good rate of 83.3%. ConclusionFor the treatment of unstable femoral neck fracture with posteromedial comminutations, cannulated screws and medial bracing plate combined with bone allograft are dramatically effective due to earlier weight bearing, faster fracture healing, and better hip function recovery.
The study aims to investigate the effect of the ratio of long axis to short axis (RLS) of upright polypropylene infusion bag on discharging process and to search the best RLS. Aiming at five different RLS (1.5:1, 2:1, 3:1, 4:1 and 5:1, respectively) with the volume of 100 mL, 250 mL and 500 mL, respectively, based on finite element method, analyzing the variation of stress distribution, emptying rate, drugging space and steadiness coefficient, etc. For the bags of the same volume, emptying rate increased with increasing of RLS, but the steadiness coefficient decreased with increasing of RLS. The specific increasing amplitude of emptying rate and decreasing range of steadiness coefficient were as follows: 20% and 49% for 100mL infusion bag, 9% and 51% for 250 mL infusion bag, and 11% and 46% for 500 mL infusion bag, respectibvely, when RLS increased from 1.5:1 to 5:1. Comparatively speaking, the increasing amplitude of the emptying rate is remarkably less than the decreasing range of the steadiness coefficient. By comprehensive consideration of both emptying rate and steadiness coefficient, lower RLS is recommended for upright polypropylene infusion bag.
The COSMIN-RoB checklist includes three sections with a total of 10 boxes, which is used to evaluate risk of bias of studies on content validity, internal structure, and other measurement properties. COSMIN classifies reliability, measurement error, criteria validity, hypothesis testing for construct validity, and responsiveness as other measurement properties, which primarily focus on the quality of the (sub)scale as a whole, rather than on the item level. Among the five measurement properties, reliability, measurement error and criteria validity are the most widely used in the studies. Therefore, this paper aims to interpret COSMIN-RoB checklist with examples to guide researchers to evaluate the risk of bias of the studies on reliability, measurement error and criteria validity of PROMs.
Objective There is few report on dynamic stabil ization for posterior cervical reconstruction. To investigate the biomechanical properties of a novel cervical spine posterior fixation using the bio-derived freeze-dried tendon in posterior cervical spine reconstruction. Methods The palmaris longus flexor tendon and metacarpal extensor tendon were collected from the death donors’ stump to prepare bio-derived tendon. Twenty fresh cervical vertebrae (C1-7) were harvested from goats and were randomly divided into 4 groups (n=5): intact group (group A); injury control group (group B); screwrods fixation group, fixed with screw-rods on C3，4 (group C); tendon reconstruction group, cross-fixed with bio-derived freezedried tendon on C3，4 bilatera facet joints (group D). The range of motion (ROM) values in flexion, extension, lateral bending, and axial rotation were measured. Results In flexion, the ROM values of group C were significantly lower than those of the other 3 groups (P lt; 0.05), and the ROM values of group B were significantly higher than those of groups A and D (P lt; 0.05). In extension, lateral bending, and axial rotation, the ROM values of group C were significantly lower than those of groups A, B, and D (P lt; 0.05), and no significant difference was found within the other 3 groups (P gt; 0.05). Conclusion The novel cervical spine posterior fixation using the bio-derived frozen-dried tendon can provide enough stabil ity in flexion motion, but it can not limit the lateral bending and axial rotation motion, which can provide dynamic stabil ization in animal model.
Objective To evaluate the clinical effect of Halo-vest in treatment of unstable upper cervical spine. Methods From March 1997 to October 2002, 16 cases of unstable upper cervical spineswere treated and immobilized by Halovest, aged from 14 to 53 years. There were 3 cases of isolated Jefferson fractures, 4 cases of isolated Hangman fractures and 1 case of Anderson type Ⅱ fracture. The 8 cases were immobilized for 3-4 months by Halovest. There were 3 cases of old odontoid fractures with dislocations treated by occipitocervical plate fixation and fusion, 1 case of C1 malignant tumor by posterior resection and internal fixation, 2 cases of C2 malignant tumor by anterior resection, fusion, and internal fixation; these cases were immobilized by Halo-vest during surgery. There were 1 case of C2,3 tuberculosis were treated by anterior debridement and fusion, and 1 case of gooseneck deformity by anterior decompression, fusion and screw fixation after resection of C2-7 , the 2 cases were immobilized for 3 months by Halo-vest.Of 16 cases, there were 8 cases accompanied with spinal cord syndrome. Results Fifteen cases were followed up 6 months to 5 years. Anterior arch ununion and posteriorarch osseous healing occurred in 1 case of Jefferson fracture. Other fractures and embedded bones became osseous fusion. One case of C2 malignant tumorrecurred 8 months after operation. Spinal cord syndrome of all patients disappeared. Conclusion Halo-vest immobilization is an effective method for conservative treatment and stable reconstruction of unstable upper cervical spine.
It will cause hidden trouble on clinical application if the uroflowmeter is out of control. This paper introduces a scheme of uroflowmeter calibration device based on digital signal processor (DSP) and gear pump and shows studies of its feasibility. According to the research plan, we analyzed its stability, repeatability and linearity by building a testing system and carried out experiments on it. The flow test system is composed of DSP, gear pump and other components. The test results showed that the system could produce a stable water flow with high precision of repeated measurement and different flow rate. The test system can calibrate the urine flow rate well within the range of 9~50 mL/s which has clinical significance, and the flow error is less than 1%, which meets the technical requirements of the calibration apparatus. The research scheme of uroflowmeter calibration device on DSP and gear pump is feasible.