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@#Introduction: The current standard treatment for ankle syndesmosis injury is static screw fixation. Dynamic fixation was developed to restore the dynamic function of the syndesmosis. The purpose of this study was to determine that which of static screw fixation and dynamic fixation is better for treatment of ankle syndesmosis injury in pronationexternal rotation fractures. Materials and methods: Thirty patients were treated with dynamic fixation (DF group) and 28 patients with static screw fixation (SF group). The primary outcome was Olerud–Molander Ankle Outcome Score. The secondary outcome were Visual Analogue Scale score and American Orthopedic Foot and Ankle Society score, radiographic outcomes, complications and cost effectiveness. To evaluate the radiographic outcome, the tibiofibular clear space, tibiofibular overlap, and medial clear space were compared using the pre-operative and last follow-up plain radiographs. To evaluate the cost effectiveness, the total hospital cost was compared between the two groups Results: There was no significant difference in primary outcome. Moreover, there were no significant difference in secondary outcome including Visual Analogue Scale score and American Orthopedic Foot and Ankle Society score and radiographic outcome. Two cases of reduction loss and four cases of screw breakage were observed in the SF group. No complication in the DF group was observed. Dynamic fixation was more cost effective than static screw fixation with respect to the total hospital cost. Conclusion: Although dynamic fixation provided similar clinical and radiologic outcome, dynamic fixation is more cost effective with fewer complications than static screw fixation in ankle syndesmosis injury of pronation-external rotation fractures.
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Objective To evaluate the influence of dynamic fixation (rotating and sliding pedicle screws) on stability of the atlantoaxial joint. Methods A series of in vitro biomechanical tests were performed using six fresh adult cervical spines (occipital bone-C4 segment) to simulate different conditions in surgery， including the intact state, the injury state, rigid fixation, rotating pedicle screw fixation, sliding pedicle screw fixation. The repeated measurement design was employed, and under intact, injury and different fixation states, the pure moment of 1.5 N·m in flexion-extension, left-right lateral bending, left-right axial rotation directions were applied using the spinal testing machine. The movement of atlantoaxial spine was measured consecutively by three-dimensional （3D） measurement system in order to analyze the range of motion (ROM) and neutral zone (NZ) of atlantoaxial joints. Results Under injury state, ROM of atlantoaxial joints was significantly larger than that under intact state during flexion, extension, lateral bending and rotation, leading to the instability of atlantoaxial joints. ROM of fixation segments was significantly reduced during flexion, extension, lateral bending and rotation after rigid and dynamic fixation. Compared with rigid fixation, dynamic fixation showed a significant ROM increase during lateral bending. NZs of fixation segments after dynamic fixation were significantly reduced. There were no significant ROM differences between rigid fixation and dynamic fixation. Conclusions The stability of atlantoaxial joints by dynamic fixation during flexion, extension and rotation was comparable to that by rigid fixation, but weaker during lateral bending. Dynamic screw fixation can maintain the relative stability of atlantoaxial joints.
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Objective: To evaluate the effectiveness of Coflex interspinous dynamic internal fixation combined with spinal fusion for lumbar disc degeneration. Methods: The clinical data of 39 patients with two-level lumbar disc degeneration who met the selection criteria between June 2010 and December 2011 was retrospectively analyzed. They were divided into group A (20 cases, simple lumbar decompression and fusion) and group B (19 cases, Coflex interspinous dynamic internal fixation combined with spinal fusion) according to different surgical methods. There was no significant difference in age, gender, disease diagnosis, lesion segment, disease duration, Oswestry disability index (ODI), visual analogue scale (VAS) score, and the intervertebral height, foramen intervertebral height (FIH), and range of motion (ROM) of upper operative segment and adjacent segment between the two groups ( P>0.05). ODI and VAS score were used to evaluate the effectiveness before operation and at last follow-up, and the improvement rates were calculated. The intervertebral height [anterior disc height (ADH), middle disc height (MDH), and posterior disc height (PDH)], FIH, and ROM were measured and compared between the two groups. Results: The operation time and intraoperative blood loss in group A were significantly more than those in group B ( P0.05); the improvement rate of VAS score in group B was significantly higher than that in group A ( t=2.245, P=0.031). There was no significant difference in the intervertebral height and FIH of the upper operative segment at last follow-up between the two groups and between preoperation and last follow-up in the two groups ( P>0.05). At last follow-up, the ADH of adjacent segment in group B was significantly higher than that in group A, and MDH, PDH, and FIH were significantly lower than those in group A ( P0.05). The ROM of adjacent segment in group A increased significantly at last follow-up ( t=2.318, P=0.026). There was significant difference in ROM of adjacent segment between the two groups ( P<0.05). Conclusion: The mid-term effectiveness of Coflex interspinous dynamic internal fixation combined with spinal fusion is similar to that of simple decompression fusion. For those patients whose adjacent segments of the responsible segments have degeneration but have no symptoms or mild symptoms, this treatment can slow down the adjacent segment degeneration.
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STUDY DESIGN: Retrospective clinical cohort study. PURPOSE: To investigate whether the combined use of dynamic pedicle screws and polyaxial pedicle screws was effective on adjacent segment pathology (ASP). OVERVIEW OF LITERATURE: Various screw and rod models have been recently developed for preventing adjacent segment disease, and hybrid systems have been described along with posterior instrumentation in the fusion segment. In the literature, although the success of dynamic systems has been demonstrated in non-fusion posterior instrumentation, it remains unclear whether the addition of a screw-based dynamic system to a fusion segment would successfully prevent ASP in the long term. METHODS: The study included 101 patients who underwent surgery for degenerative spine diseases between 2007 and 2014 with lumbar stabilization that used either polyaxial pedicle screws alone or polyaxial pedicle screws plus dynamic stabilization screws (with hinged screw heads). These two patient groups were compared using retrospectively obtained postoperative new clinical findings, Oswestry disability index (ODI) scores, visual analog scale (VAS) scores, and radiological data. RESULTS: The proportion of patients with ASP who were radiologically assessed was low (p 0.05). CONCLUSIONS: Although the combined use of dynamic screws and the static system was radiologically found to be effective for preventing ASP in patients who underwent lumbar fusion with posterior instrumentation, it did not completely eliminate ASP or result in a significant improvement in clinical ASP.
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Humanos , Estudios de Cohortes , Patología , Tornillos Pediculares , Estudios Retrospectivos , Columna Vertebral , Viperidae , Escala Visual AnalógicaRESUMEN
Objective To compare the short-term clinical effect of K-Rod pedicle dynamic fixation system and lumbar fusion for multi-ple segmental lumbar degeneration.Methods Between January 2010 and October 2012,56 patients with segmental lumbar degeneration who were accepted K-Rod pedicle dynamic fixation system and posterior lumbar interbody fusion were retrospectively reviewed.The 56 patients were divided into K-Rod and fusion group,28 patients with K-Rod pedicle dynamic fixation system and 28 cases with traditional lumbar fusion and internal fixation.Clinical assessments were based on comparion of Oswestry disability index score ,visual analogous scale (VAS),im-provement rate of low back pain,postoperative lumbar spine X-ray,average operation time and intraoperative blood loss of two groups.Results All of 56 cases were followed up for 12 to 24 months,the difference of Oswestry disability index score and VAS between two groups were not statistically significant(P >0.05),but the difference of average operation time,blood loss and the average length of stay(ALOS)were statis-tically significant(P <0.05),the K-Rod group was superior to the fusion group.Conclusion In the treatment of multiple segmental lumbar degeneration both K-Rod pedicle dynamic fixation system and traditional lumbar fusion can obtain satisfactory short-term clinical effect,but the K-Rod pedicle dynamic fixation system has advantages of less intraoperative blood loss,shorter operation time,postoperative small effects on lumbar spine mobility.
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Objective To discuss the short-term clinical effect of K-Rod pedicle dynamic fixation system for multiple segmental lumbar degeneration. Methods From January 2010 to October 2012,28 patients with multiple segmental lumbar degeneration who were accepted K-Rod pedicle dynamic fixation system were retrospectively reviewed. The short-term clinical effect were based on Oswestry disability index score,visual analogous scale ( VAS) ,improvement rate of low back pain,postoperative lumbar hyperextension, hyperbend X-ray film lumbar ROM value ( lumbar flexion mobility) ,average operation time, intraoperative blood loss. Results All of 28 cases were achieved 12 ~24 months follow-up,the difference of Oswestry disability index score and visual analogous scale ( VAS) between 12 months postoperatively and preoperatively were statistically significant,the improvement rate of low back pain was (87. 0 ± 2. 0)%,the average operation time was (99. 6 ± 16. 2) minutes,the average blood loss was (70. 5 ± 31. 5)mL,the average length of stay(ALOS) was (11. 2 ± 2. 6) days after sur-gery. Conclusion K-Rod pedicle dynamic fixation system in the treatment of multiple segmental lumbar degeneration can obtain satisfactory short-term clinical effect.
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Objective To analyze the incidence of remaining symptoms after discectomy with different operation,and investigate its causes and clinical significance.Methods Two hundred and twentyfour patients were followed up.The incidence of remaining symptoms and clinicai situation after discectomy were observed with different operation:discectomy (110 patients,single group),discectomy with bone grafting internal fixation (70 patients,fusion group),and discectomy with dynamic fixation (44 patients,non-fusion group).The SPSS 19.0 software was used to analyze the data.Results One hundred and sixpatients (47.32％,106/224) occurred remaining symptoms in 224 patients.In single group was 69 patients (62.73％,69/110),in fusion group was 26 patients (37.14％,26/70),and in non-fusion group was 11 patients (25.00％,11/44).The incidence of remaining symptoms among three groups was significant difference(x2 =22.177,P =0.000).The incidence of remaining symptoms in single group was significantly higher than that in non-fusion group and fusion group (x2 =17.921,P =0.000;x2 =11.235,P =0.001).The incidence of remaining symptoms in non-fusion group and fusion group had no significant difference (x2 =1.817,P =0.178).Conclusions There is significantly different in the incidence of lumbar disc herniation with different surgery methods.Discectomy with bone grafting internal fixation and with dynamic fixation can effectively reduce the incidence of remaining symptoms.
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Objective Currently there is little study on the K-Rod pedicle fixation system in the treatment of far lateral lum-ber disc hernaition with multiple segment degeneration.The study was to compare the short-term efficay of K-Rod pedicle dynamic fixa-tion system and lumbar fusion for far lateral lumber disc herniation with multiple segment degeneration. Methods Retrospective a-nalysis were made on 56 patients with lumbar intervertebral disc herniation with multiple segment degeneration who received operation in General Hospital of Shenyang Military Region from January 2010 to October 2012.They were divided into K-Rod group (combined treatment of lumbar fusion and adjacent degenerative segment unfusion) and traditional fusion group according to different treatments. 28 patients in K-Rod group were treated with K-Rod pedicle dynamic fixation system and 28 cases in traditional fusion group were trea-ted with traditional lumbar fusion and internal fixation.Comparative analysis were made on the indexes before and after operation be-tween two groups, including Oswestry disability index, visual analogous scale (VAS) ,improvement rate of low back pain, postopera-tive lumbar spine X-ray, operation time, intraoperative blood loss and postoperative average length of stay. Results 12 to 24 months follow-up were achieved on 56 cases.The Oswestry function score and visual analog scale for both groups were improved significantly at 12 months after operation, and the difference was of statistical significance (P0.05), while the average operation time ([119.6 ±14.2] min vs [155.5 ±17.5]min), the average blood loss ([235.5 ±32.5] mL vs [367.5 ±29. 5] mL), the average length of stay (ALOS) ([10.5 ±2.2] vs [14.2 ±2.6]d) between K-Rod group and traditional fusion group were of significant difference(P<0.05). Conclusion In the treatment of far lateral lumber disc hernaition with multiple segment degeneration, the K-Rod pedicle dynamic fixation system atrributes to less intraoperative blood loss, shorter operation time and little postoperative effect on lumbar spine mobility.
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It is known that rigid pedicle screw fixation may cause abnormal stress concentration on the posterior part of the spine, which may lead to stress concentration on the fixation device; meanwhile, due to the motion limitation to the fixed segment, the excessive motion at the adjacent segment may further fortify the disc degeneration. To solve these issues, the dynamic fixation is used in clinic, and many studies have investigated the biomechanical mechanism and clinical outcome of the dynamic fixation. The ideal dynamic fixation should meet the following conditions: offering enough stabilization for the fixed segment; reducing the load on the fixation device through enhancing the strain on the anterior vertebral bodies; preventing the degeneration at the adjacent segment; controlling the horizontal shear force at the fixed segment. In this article, the biomechanical properties and clinical application of the posterior dynamic fixation were reviewed and the biomechanical mechanisms of different dynamic fixations were compared.
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Objective To simulate clinical operation and investigate feasibility of Coflex dynamic device for fixing L5/S1 segment of lower lumbar degenerative diseases. Methods The lower lumbar-sacral digital model was extracted from platform of the second generation of Chinese Digitized Human “Male No.23” data set, and three finite element (FE) models (the model of normal lower lumbar sacrum, L4/5 and L5/S1 segment fixed with Coflex) were developed respectively using a series of CAX software. According to the spinal three-column loading theory and the lower lumbar physiological behaviors, FE model tests were analyzed, validated and compared under the physiological load of upright standing, anteflexion and extension. Results The FE models of normal lower lumbar sacrum (Healthy), Coflex fixed-L4/5 segment (L4/5), Coflex fixed-L5/S1 segment (L5/S1) were developed, respectively. Based on biomechanical indexes (stability and compatibility) of the controlled trial for the FE model, the two Coflex-fixed FE models showed similar biomechanical effects for fixing the lower lumbar. Conclusions The controlled trials of FE models provide biomechanical evidence for the fixation of lower lumbar L5/S1 segment by Coflex dynamic device, which is of significance for application of Coflex in fixing L5/S1 segment in clinic.
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Objective To determine the lumbar anatomical structure parameters of the lumbar spine posterior column and its sample data of three-dimensional conformation,and based on these data to design the lumber laminar screw dynamic fixation system.Methods 20 human L3 ～ S1 bone specimens,the thickness of the lumber laminar region were measured to obtain the normal anatomical parameters of the lumbar laminar.And 20 healthy lumbar vertebrae L3-S1 for three-dimensional reconstruction were detected by CT scan,which could obtain the structure data of the normal lumbar posterior three-dimensional conformation,and to obtain conformational sample data of three-dimensional space of the posterior structure.Results Lumbar lamina medial 1/3 could serve as a spine laminar screw setting area by anatomical observations and measurements.Lamina thickness of L3-4 on average (6.6 ±0.9) mm,L5 ～ S1average (6.0 ± 0.6) mm.Lumber laminar screw length 6.5 ～ 8.0mm could meet the requirements of bilateral cortical fixation.Conclusion Lower lumbar spinal lamina area can serve as the region to fix the bilateral cortical bone screw,and the optimal length of the laminar screw is 6.5 ～ 8.0rmm.
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Objective To explore the efficacy and safety of coflex interspinous dynamic fixation device implantation in the lumbar spinal stenosis. Methods Eighty-three patients with lumbar spinal stenosis were randomly divided into two groups, and 80 cases were followed up. Coflex group (38 patients) received coflex implantation,posterior lumbar interbody fusion (PLIF) group(42 patients) received PLIF treatment. Indicators of surgical trauma degree (operation time, blood loss volume, wound drainage volume within 48 hours, incision pain (VAS) score after surgery 3 days,postoperative ambulation time),indicators of clinical effect (waist and leg pain VAS scores,Japan Orthopaedic Association JOA score,Oswestry functional disability index ODI score),intervertebral space height and median sagittal diameter (MSO) were measured and compared between the two groups. Results In the Coflex group, the operation time, blood loss volume, wound drainage volume within 48 hours, incision pain (VAS) score after surgery 3 days,postoperative ambulation time were (104.3 ±9.5) min,(230. 7 ±29.6) ml,(110. 6 ±34. 5)ml,3. 2 ±1.3, (13. 6 ±2.0) d,which were significantly lower than those of (174. 6 ±24. 2) min,(536. 8 ±163.3) ml, (319. 2 ± 142. 8) ml,4. 8 ±2. 7, (15. 7 ±2. 6) d in the PLIF group(t= 16. 720,11. 380,8. 771,3. 320,4.018,Ps 0. 05) on severe complications such as internal fixation loosening and spinous process fractures.Conclusion The two surgical methods both can effectively increase the foraminal area and intervertebral height to maintain the stability of the spinal posterior colum. However, Coflex interspinous dynamic fixation device implantation had more advantages,such as shorter operation time,less bleeding,less trauma,and early functional exercises.
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[Objective]To analyze the change of intervertebral disc Von Mises stress on the adjacent segment after "U" shape dynamic fixation for lumbar with finite element method. [Method]The three-dimensional finite element models of the lumbar dynamic fixation and rigid fixation were established by using Mimics11.11 and Abaqus6.51 softwares.Loads used in this study were axial compressive,flexion,extension,lateral bending,and rotation forces.The intervertebral disc Von Mises stress of the adjacent segment was analyzed and compared.[Result]In the same shearing load of 500 N,the intervertebral disc Von Mises stress of the adjacent segment in the dynamic fixation model was lower than rigid fixation model under axial compressive,flexion,extension,lateral bending,and rotation forces,especially at lateral of the intervertebral disc,and there were significant difference between dynamic fixation group and rigid fixation group(P