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Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft, and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery. Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh, bone graft, plate and screw fixation was established，and C3-7 segment intact model of cervical vertebra was also constructed. The torque moment of 0.5, 1.0, 1.5, 2.0 N﹒m was applied to the ACCF surgery model. The ROM, maximum stress in facet joint and stress distributions on internal fixation devices under flexion, extension, lateral bending and torsion movement were analyzed. Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery. In the case of 1.0 N﹒m torque moment and 50 N preload, the ROM of reconstructed C5, C3-4, C6-7 and C3-7 segment was reduced by 81%, 62%, 58% and 80% compared with the intact model. The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased. The stress of titanium mesh was mainly distributed on the compression side of movement, and high stress was located in the roots of screws. Conclusions ACCF surgery can promote the stability of cervical spine, decrease the stress in facet joint of operation segment, and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy. The research results will provide some theoretical basis for clinical application of ACCF.
ABSTRACT
Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft,and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery.Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh,bone graft,plate and screw fixation was established,and C3-7 segment intact model of cervical vertebra was also constructed.The torque moment of 0.5,1.0,1.5,2.0 N · m was applied to the ACCF surgery model.The ROM,maximum stress in facet joint and stress distributions on internal fixation devices under flexion,extension,lateral bending and axial rotation movement were analyzed.Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery.In the case of 1.0 N · m tomue moment and 50 N preload,the ROM of reconstructed C5,C3-4,C6-7 and C3-7 segment was reduced by 81％,62％,58％ and 80％ compared with the intact model.The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased.The stress of titanium mesh was mainly distributed on the compression side of movement,and high stress was located in the roots of screws.Conclusions ACCF surgery can promote the stability of cewical spine,decrease the stress in facet joint of operation segment,and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy.The research results will provide some theoretical basis for clinical application of ACCF surgery.
ABSTRACT
Objective To establish the three-dimensional finite element model of human lower cervical spine C3-7 motion segments after anterior cervical corpectomy and fusion (ACCF) surgery with titanium mesh and bone graft,and to analyze the stability of cervical spine and stress distribution of internal fixation devices after ACCF surgery.Methods The finite element model of cervical spine C3-7 segments after ACCF of C5 segment with titanium mesh,bone graft,plate and screw fixation was established,and C3-7 segment intact model of cervical vertebra was also constructed.The torque moment of 0.5,1.0,1.5,2.0 N · m was applied to the ACCF surgery model.The ROM,maximum stress in facet joint and stress distributions on internal fixation devices under flexion,extension,lateral bending and axial rotation movement were analyzed.Results ROM of reconstructed C5 segment increased with the torque moment increasing after ACCF surgery.In the case of 1.0 N · m tomue moment and 50 N preload,the ROM of reconstructed C5,C3-4,C6-7 and C3-7 segment was reduced by 81％,62％,58％ and 80％ compared with the intact model.The maximum stress in facet joint of reconstructed C5 segment reduced and the stress in adjacent segments significantly increased.The stress of titanium mesh was mainly distributed on the compression side of movement,and high stress was located in the roots of screws.Conclusions ACCF surgery can promote the stability of cewical spine,decrease the stress in facet joint of operation segment,and has better treatment effect on easing compression from spinal cord caused by cervical spondylotic myelopathy.The research results will provide some theoretical basis for clinical application of ACCF surgery.
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<p><b>BACKGROUND</b>Osteoarthritis often affects the joint bilaterally, and the single-stage (SS) unicompartmental knee arthroplasty (UKA) is advantageous in terms of a single anesthesia administration, a short hospital stay, lower medical costs, and enhanced patient convenience. However, the complication risk of SS UKA continues to be debated. The aim of this article was to evaluate the clinical effectiveness, complications, and functional recovery of SS and two-stage (TS) UKA.</p><p><b>METHODS</b>From January 2008 to December 2013, we compared a series of 36 SS UKA with 45 TS UKA for osteoarthritis. The mean age was 65.4 years (range: 55-75 years). The mean body mass index was 25.2 kg/m 2 (range: 22-29 kg/m 2 ). The pre- and post-operative Oxford Knee Scores (OKSs), complications, operative times, tourniquet times, the amount of drainage, and hemoglobin (Hb) were evaluated. The Chi-square test, Fisher's exact test, and paired and grouped t-tests were used in this study.</p><p><b>RESULTS</b>The mean follow-up was 50 months. No complications of death, fat embolism, deep vein thrombosis, and prosthetic infection were reported. Patients who underwent SS UKA had a shorter cumulative anesthesia time (113.5 vs. 133.0 min, P < 0.01). There were no significant variations between the values of the mean tourniquet time, the amount of drainage, pre- and post-operative Hb in the different groups. No patient required a blood transfusion. No statistical differences were found in the complications between two groups (P > 0.05). At the final follow-up, the mean OKS improved from 39.48 ± 5.69 to 18.83 ± 3.82 (P < 0.01), with no statistical differences between the two groups (P > 0.05). Patients who underwent SS UKA had a faster recovery.</p><p><b>CONCLUSIONS</b>The single-staged UKA offers the benefits of a single anesthesia administration, reduced total anesthetic time, decreased overall rehabilitation time, and absence of an increase in perioperative mortality or complications compared with the TS bilateral UKA.</p>
Subject(s)
Aged , Female , Humans , Male , Middle Aged , Arthroplasty, Replacement, Knee , Methods , Knee Joint , General Surgery , Operative Time , Osteoarthritis, Knee , General Surgery , Recovery of Function , Treatment OutcomeABSTRACT
<p><b>OBJECTIVE</b>To determine whether anterior knee pain and/or radiological evidences of degeneration of the patellofemoral joint influence the outcome of unicompartmental knee arthroplasty (UKA).</p><p><b>METHODS</b>Between January 2006 and December 2010, 95 consecutive patients (100 knees) with unicompartmental knee osteoarthritis were treated with Oxford UKA, including 34 males and 61 females. The mean age was 68.2 years (range, 55-82 years). The average Body Mass Index was 26.3 kg/m(2)(range, 24-28 kg/m(2)). Pre-operative there were 43 knees (43.0%) with anterior knee pain and 57 knees (57.0%) without it. Pre-operative radiological status of the patellefemoral joint were defined using Ahlback and Altman systems. The pre- and post-operative results of Oxford Knee Score (OKS), American Knee Society Score (AKS) and Western Ontario and Macmaster (WOMAC) were compared using paired t-test, the results between different groups were compared using grouped t-test.</p><p><b>RESULTS</b>All cases were followed up for average 50 months (24-84 months). At the last follow-up, none had complications of infection, fat embolism, deep vein thrombosis, malposition of prosthesis, dislocation or loosing. The mean femoral component alignment was -0.7° ± 5.2° (valgus/varus), -0.8° ± 4.5°(flexion/extension); the mean tibial component alignment was -0.1° ± 2.2°(valgus/varus), -0.4° ± 2.4° (flexion/extension). The clinical outcomes were significantly improved compared with pre-operation regardless of presence (OKS: t = 19.04, P < 0.01; AKS knee:t = 38.56, P < 0.01;AKS function:t = 39.29, P < 0.01;WOMAC:t = 43.22, P < 0.01) or absence (OKS: t = 31.57, P < 0.01; AKS knee:t = 40.34, P < 0.01; AKS function:t = 43.62, P < 0.01; WOMAC: t = 47.06, P < 0.01) of anterior knee pain. The results were significantly improved compared with pre-operation (P < 0.01) regardless of whether degeneration of the patellofemoral joint. There was no statistically significant difference in outcome between patients with evidence of degeneration in the medial patellofemoral joint and those without (P > 0.05) . Patients with lateral patellofemoral degeneration had a worse score than those without, OKS (t = 2.56, P = 0.01) and WOMAC (t = 2.20, P = 0.03) by the Altman score, OKS (t = 2.29, P = 0.02) by the Ahlback score. For AKS measures there was no statistically significant difference in outcome (P > 0.05) .</p><p><b>CONCLUSIONS</b>Neither anterior knee pain nor radiological evidence of medial patellofemoral joint degeneration would influnence the outcome of UKA, lateral patellofemoral joint degeneration have an increased risk of a poor result.</p>