骨密度对距下关节融合初稳性影响的三维有限元分析

目的 通过有限元分析的方法研究骨密度对于距下关节融合初稳性的影响. 方法 选取1名男性健康志愿者,25岁,体质量为70kg.基于志愿者右足的三维CT扫描数据利用Mimics 13.0、Geomagic 10.0等软件重建距下关节融合的三维有限元双顶模型:即距骨颈联合距骨顶前外、后外、前内、后内侧4种双钉模型,同时通过降低骨的弹性模量模拟不同程度的疏松骨质,最后将模型导入Abaqus 6.9软件进行赋值、划分网格,对每个模型施加4N·m的内旋、外旋作用力,通过计算分析模型应力后距下关节面间的相对位移来评估骨密度对距下关节融合初稳性的影响. 结果 随着骨密度的降低,4种融合模型应力后关节面间的相对位移峰值均增大;距骨颈联合距骨前外侧顶的双钉模型在正常骨密度和骨质疏松存在的情况下,其应力后关节面间相对位移峰值均较其他模型低,是距下关节融合最优的选择;而距骨颈联合距骨后内侧顶的双钉模型,应力后关节面间相对位置峰值最大,关节融合时应避免使用此种配置. 结论 骨密度越低融合后稳定性越差;距骨颈联合前外侧顶双钉模型对于正常或疏松骨质的距下关节融合都具有最好的稳定性,是距下关节融合最优的选择.     

The optimum position of arthrodesis of the ankle. A gait study of the knee and ankle

Findings from biomechanical analyses of gait were used to estimate the optimum position of arthrodesis of the ankle. Nineteen patients who were followed for an average of 10.4 years (range, four to seventeen years) were studied. By including the knee in the analysis as well as studying the effects on gait of different ground conditions, objective data for the weight-bearing extremities in the transverse, sagittal, and coronal planes were generated. Genu recurvatum was shown to be associated with a plantar-flexion position of fusion of the ankle. Laxity of the medial collateral ligament of the knee was noted in twelve patients (63 per cent). Among these patients, in three (16 per cent) the laxity was graded as moderate to severe, possibly due to external rotation of the extremity during gait to avoid rolling over the rigid plantar-flexed ankle. The patterns of gait showed that a valgus position of the arthrodesis is more advantageous and provides more normal gait, particularly on uneven ground. To attain more normal function of the knee and improve performance on rough ground, the optimum position of arthrodesis of the ankle appears to be neutral flexion, slight (zero to 5 degrees) valgus angulation, and approximately 5 to 10 degrees of external rotation. Posterior displacement of the talus under the tibia tends to produce a more normal pattern of gait and decreases the stress at the knee. CLINICAL RELEVANCE: This study has shown the ideal position of fusion of the ankle to be neutral flexion, slight (zero to 5 degrees) valgus angulation of the hind part of the foot, and 5 to 10 degrees of external rotation. This position allows the greatest compensatory motion at the foot and places the least strain on the knee.     

A new technique of ankle arthrodesis.

A new technique of ankle arthrodesis is described and the results of 12 consecutive procedures are assessed. The method described employs three cannulated transfixion screws and an anterior approach to the ankle. Eleven of the 12 ankles proceeded to solid fusion. One patient developed a painless fibrous non-union. There were no other significant complications. This simple technique provides good compression and adequate resistance to rotatory and angulatory stresses about the ankle fusion site.     

不同载荷对正常踝关节影响的有限元研究

目的 利用有限元法分析踝关节受到不同载荷后各组织的应力和位移分布. 方法 选取1名30岁男性健康志愿者的右足螺旋CT扫描图像,通过Mimics10.01、SolidWorks2009等软件进行踝关节的三维重建、模拟韧带连接和生成关节接触等,分别建立了包含骨-韧带复合体的5块骨和9块骨的正常踝关节三维有限元模型.在模型中设置相应的边界条件分别模拟踝关节在中立位站立、内翻、外翻、内旋及外旋时所受外力,进行加载运算. 结果 本研究获得了踝关节在5种加载中各组织的Von Mises应力分布,其中距腓前韧带在除外翻加载外的其他4种加载下应力均明显增加,为承受载荷的主要装置;同时获得了各种载荷下各关节的接触力及各骨与关节的活动度. 结论 本研究所建立的正常踝关节三维有限元模型经验证有效,其对于认识踝关节内部的力学传递机制及踝关节的损伤特点具有重要价值.     

The results of ankle arthrodesis

The results are presented of 47 compression arthrodeses of the ankle performed for osteoarthritis in 44 patients. In 26 cases the transverse anterior incision of Charnley had been used and in 21 cases medial and lateral incisions with division of the malleoli. Complications included infection (19%), non-union (14.9%) and malposition requiring a further procedure (8.5%). Three patients (6.4%) eventually had an amputation. Clinical assessment using a standard grading method showed that the functional result was not related to the angle of plantar flexion of the ankle, but was related to the varus/valgus position of the heel, the neutral position being associated with the best results. The anterior approach was more reliable in avoiding varus or valgus of the heel.     

前踝撞击征发生机制的生物力学有限元分析

[目的]通过构建准确完整的全足三维有限元模型并进行应力分析,模拟后足踩地过程,以此探究前踝多发撞击的生物力学机制。[方法]在中立位无负重状态下,基于踝关节解剖结构,构建包括骨与足周围软组织及关节韧带的全足三维有限元模型,通过与既往研究结论相对比,验证有限元模型的准确性,并对模型设定边界条件、施加载荷进行应力分析,研究前踝在后足踩落地过程中的应力分布及位移情况。[结果]建立了包含28块骨性结构、56条韧带及足周围软组织的全足三维有限元模型,共219 599个节点,938 845个单元,模型具有较好的几何相似性。有限元分析的结果表明,随着足跟逐渐踩地,前踝始终为应力集中和位移最大的区域,距骨前外侧应力峰值从0.058 MPa增加到了0.225 MPa,距骨头的最大位移量从0.563 mm增加到了1.626 mm。[结论]在正常的落地过程中,前踝不仅应力值始终最大,而且位移量也始终最大,因此前踝关节容易发生撞击。     

Arthroscopic arthrodesis of the ankle joint.

SUMMARY: The authors report on 15 cases of arthrodesis of the ankle joint performed by operative arthroscopy. The follow-up ranges from 1 to 3 years, and 100% of the ankle joints achieved fusion at an average of 11.5 weeks. Two of the patients had some hindfoot pain, probably because of degenerative changes to their subtalar joints, even with this short follow-up. Five patients required further surgical treatment to correct complications related to infection, symptomatic hardware, or subtalar joint arthritis. Although the fusion rate is certainly encouraging, this procedure in the senior author's hand has a significant complication rate.     

踝关节融合术两种固定方式的三维有限元分析

[目的]通过三维有限元方法对踝关节融合的两种固定方式进行对比评价,并对其固定生物力学机制进行初步分析,为其临床应用提供理论依据.[方法]以正常人体踝关节CT扫描断层数据为基础,建立踝关节三维模型,模拟进行3螺钉固定和腓骨支撑固定手术,对模型中立、背屈、内旋和外旋4种载荷进行加载,分别进行有限元求解.[结果]3螺钉固定与腓骨支撑固定在抗旋转载荷上无明显差别,而在对抗背屈载荷作用优于腓骨支撑固定;在融合加压效果方面,3螺钉固定优于腓骨支撑固定,而腓骨支撑固定在移除外侧支撑腓骨后,加压作用有所下降;与腓骨支撑固定相比,3螺钉固定后的胫骨应力峰值更高且分布更集中,术后发生应力性骨折风险较高.[结论]在正常骨质条件下,3螺钉固定的生物力学稳定性以及融合加压效果均优于腓骨支撑固定,临床上建议首选3螺钉固定;而腓骨支撑固定的安全性较高,更适用于骨质条件较差的患者.     

踝关节周围韧带损伤对距骨稳定性影响的有限元分析

目的有限元法分析踝关节周围韧带损伤对距骨生物力学稳定性的影响,为临床踝关节周围韧带损伤的治疗提供理论依据。方法基于正常男性的足踝部螺旋CT扫描数据,运用三维重建软件,建立足踝部三维几何模型,最后导入Abaqus 6.9软件中,模拟人体踝关节内旋、外旋的受力状况,分析踝关节周围韧带损伤后距骨各关节面的接触压力及VonMises应力分布。结果建立包括骨、软骨、韧带在内的正常人体足踝部三维有限元模型,踝关节周围韧带在踝关节内旋、外旋时对距骨的生物力学影响不同。结论在外旋作用力下胫距后韧带对踝关节的稳定性具有重要作用,而在内旋作用力下跟腓韧带对踝关节的稳定性具有重要作用。     

Transarticular cross-screw fixation. A technique of ankle arthrodesis

Many techniques of ankle arthrodesis have been described. Failure rates of up to 40% have been reported in the past. In this study, a technique for internal fixation of ankle fusions was employed using transarticular crossed-screw fixation. This provides bony coaptation, compression, and immobilization necessary for reliable union. Thirty-five patients had ankle arthrodesis with this technique of internal fixation and 12 patients had ankle fusions with Charnley compression arthrodesis. Follow-up evaluation averaged two years. The fusion rate was 100% (35 fusions of 35 attempts) with the transarticular crossed-screw technique and 83% (ten fusions of 12 attempts) with compression arthrodesis.     

A technique for distal tibial bone graft for arthrodesis of the foot and ankle

Hindfoot and forefoot arthrodeses procedures are commonly performed using autogenous bone graft harvested from the distal tibia. A new technique is described for obtaining cancellous bone graft from the distal tibia using a bone graft harvesting system specifically designed to obtain morsellized material through a small incision site. The use of this device in association with low dose fluoroscopy and backfilling of the defect with osteoconductive synthetic graft material is also discussed.     

The long-term results of ankle arthrodesis

The results of 62 ankle arthrodeses, mostly performed for osteoarthritis, have been reviewed; of these, 39 were examined clinically and radiographically after an average follow-up period of seven years. Compression arthrodesis was associated with the highest incidence of complications, and an anterior sliding graft gave the most satisfactory results. Very few patients required modification of their footwear; most could walk independently with a slight limp and were able to return to their pre-operative work. However, after operation, the ability to run and to participate in vigorous sporting activities was limited. Complications included wound infection, non-union, and some change in midtarsal mobility, but excellent pain relief was reported by all patients.     

Open versus arthroscopic ankle arthrodesis: a comparative study.

A retrospective review was undertaken for 36 patients who underwent ankle arthrodesis. Nineteen patients underwent an arthroscopic ankle arthrodesis, and 17 patients underwent an open arthrodesis. Only patients with limited angular deformities were suitable candidates for an arthroscopic arthrodesis. The open arthrodesis group inclusion criteria were defined by the maximum coronal and sagittal plane deformity in the arthroscopic group. Perioperative parameters were compared and analyzed. Arthroscopic ankle arthrodesis yielded comparable fusion rates to open ankle arthrodesis, with significantly less morbidity, shorter operative times, shorter tourniquet times, less blood loss, and shorter hospital stays. Arthroscopic ankle arthrodesis is a valid alternative to traditional open arthrodesis of the ankle for selected patients with ankle arthritis.     

Posterior internal compression arthrodesis of the ankle.

We have reviewed the results of 19 ankle arthrodeses in 18 patients by a new technique of posterior internal compression. Sixteen of the ankles fused at a mean time of 14 weeks and the other three after reoperation. Complications included one case each of infection, Sudeck's atrophy and non-fatal pulmonary embolism. Clinical assessment using Mazur's ankle score showed excellent or good results in nine ankles and three painfree ankles in patients who were wheelchair-bound for other reasons. The mean position of fusion was in 1.7 degrees equinus and 0.8 degrees varus, and the mean range of midtarsal movements was 15.8 degrees. Twelve patients showed radiographic signs of talonavicular or subtalar osteoarthritis.     

A simple technique for arthrodesis of the ankle

We report the results of a simple technique of ankle arthrodesis which is, however, indicated only when the foot can be reduced manually to a functional position. A special milling-cutter with an expulsion piston is used to obtain a cylindrical bone graft which is reintroduced having been reversed from left to right and rotated through 90 degrees. The operation is simple and very rapid. It has been performed on 72 patients, 62 of whom have been followed up for an average of six years. Fifty-seven were painless with bony fusion in a functional position; one was solid and painless but in valgus. In only four patients were the results unsatisfactory.     

微创踝关节融合术治疗足踝创伤性关节炎的疗效观察

目的：观察关节镜下微创踝关节融合术治疗足踝创伤性关节炎的疗效。方法回顾性分析2009年1月至2012年12月在我院接受微创及开放式踝关节融合术的26例创伤性踝关节炎病人的临床资料,按治疗方法不同分为微创组（10例）和开放组（16例）,对比两组病人术后6个月及1年的骨性融合率和美国足踝外科医师协会（AOFAS）踝与后足功能评分。结果术后6个月时,微创组的骨性融合率为80.0%（8/10）,高于开放组的31.3%（5/16）,差异有统计学意义（χ2=5.850,P=0.016）;术后1年时两组病人全部达到骨性融合。术后6个月,两组病人的AOFAS踝与后足功能评分差异无统计学意义（P＞0.05）;术后1年时,微创组的AOFAS评分为（75.3±2.7）分,明显高于开放组的（68.8±2.5）分,差异有统计学意义（χ2=7.568,P＜0.001）。结论关节镜下踝关节融合术在提高早期骨性融合率及改善足踝功能方面较开放式踝关节融合术更具优势。     

Revision arthrodesis of the ankle

Background and purpose Recent meta-analyses have suggested similar wound infection rates when using single- or multiple-dose antibiotic prophylaxis in the operative management of closed long bone fractures. In order to assist clinicians in choosing the optimal prophylaxis strategy, we performed a cost-effectiveness analysis comparing single- and multiple-dose prophylaxis.

Methods A cost-effectiveness analysis comparing the two prophylactic strategies was performed using time horizons of 60 days and 1 year. Infection probabilities, costs, and quality-adjusted life days (QALD) for each strategy were estimated from the literature. All costs were reported in 2007 US dollars. A base case analysis was performed for the surgical treatment of a closed ankle fracture. Sensitivity analysis was performed for all variables, including probabilistic sensitivity analysis using Monte Carlo simulation.

Results Single-dose prophylaxis results in lower cost and a similar amount of quality-adjusted life days gained. The single-dose strategy had an average cost of $2,576 for an average gain of 272 QALD. Multiple doses had an average cost of $2,596 for 272 QALD gained. These results are sensitive to the incidence of surgical site infection and deep wound infection for the single-dose treatment arm. Probabilistic sensitivity analysis using all model variables also demonstrated preference for the single-dose strategy.

Interpretation Assuming similar infection rates between the prophylactic groups, our results suggest that single-dose prophylaxis is slightly more cost-effective than multiple-dose regimens for the treatment of closed fractures. Extensive sensitivity analysis demonstrates these results to be stable using published meta-analysis infection rates.     

Use of implantable bone growth stimulation in Charcot ankle arthrodesis

BACKGROUND: The purpose of this study was to review the results of arthrodesis of the Charcot hindfoot when an implantable bone growth stimulator was added to the procedure. Arthrodesis of the Charcot hindfoot has a high nonunion and complication rate. METHODS: Ten patients (ages 50 to 69 years) with Charcot neuroarthropathy of the ankle, hindfoot, or both had arthrodesis with use of rigid internal fixation and an implantable bone growth stimulator. There were six tibiotalocalcaneal, two pantalar, and two tibiocalcaneal arthrodeses. An intramedullary nail was used in nine patients and a blade plate was used in one patient. All but one patient was diabetic. Four of the ten patients had preoperative osteomyelitis or postoperative infection. Another patient had purulent drainage, although cultures were negative. Four patients had a preoperative ulceration. Five patients had a two-stage procedure for debridement of infected bone, removal of hardware, and placement of antibiotic beads. Autogenous bone graft from the distal fibula or proximal tibia was used in all patients. RESULTS: One patient with a preoperative osteomyelitis developed a stable ankle pseudarthrosis. The other nine patients fused at an average of 3.7 months after surgery for a fusion rate of 90%. There were two major complications and eight minor complications. There were no amputations. All patients were ambulatory in a double upright brace or shoes for diabetic patients and were free of ulceration at the time of followup. Average American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot score improved from 21 preoperatively to 59 postoperatively. CONCLUSIONS: The adjunctive use of an implantable bone growth stimulator in conjunction with rigid internal fixation, autogenous bone grafting, and sound operative technique may enhance the outcome and fusion rate in patients undergoing arthrodesis for Charcot neuroarthropathy of the ankle and hindfoot.     

Quality of life 20 years after arthrodesis of the ankle. A study of adjacent joints

biotalar fusion is considered to be the standard treatment for end-stage post-traumatic arthritis of the ankle. We report a retrospective, objective long-term study of the quality of life of 17 patients with 18 arthrodeses of the ankle, over a period of more than 20 years. We looked particularly for correlation between clinical and radiological signs of osteoarthritis in adjoining joints. At serial physical examinations, clinical grades were awarded according to the Olerud Molander Ankle (OMA) score. Any degree of degenerative change in the adjoining joints was recorded on standing radiographs. Patients filled out a SF-36 Health Survey form. Subjectively, 50% of patients were not handicapped in the performance of daily activities and 44% were in the same job as at the time of injury. At follow-up the mean OMA score was 59.4 points, the visual analogue scale was 1.99 and the radiological score was 2.7. The SF-36 for physical function, emotional disturbance and bodily pain revealed significant deficits. There was a significant correlation between the OMA and the radiological score (p = 0.05), and between the clinical and the SF-36 score (p = 0.01), but no significant correlation between the radiological score and the SF-36 score. Arthrodesis of the ankle leads to deficits in the functional outcome, to limitations in the activities of daily living and to radiological changes in the adjoining joints. The clinical outcome score correlates closely with the SF-36 score.     

Ankle conFUSION: The quality and readability of information on the internet relating to ankle arthrodesis

BackgroundThe internet is an important source of information for patients undergoing surgery. Multiple studies have identified inappropriately high reading levels of patient information online. The average reading level in the United States is 7–8th grade. Multiple organisations have recommended that patient information not exceed 6th grade level. This study aims to evaluate the reading levels and quality of information regarding ankle fusion surgery online.MethodsGoogle, Bing and Yahoo were searched (MeSH “ankle fusion”, “ankle arthrodesis”) and the top 30 URLs analysed. Readability was assessed using an online readability calculator to produce 3 scores (Gunning FOG, Flesch Kincaid Grade and Flesch Reading Ease). Quality was assessed using a HONcode detection web-extension and the JAMA benchmark criteria.ResultsNinety-eight webpages were identified. The mean Flesch Kincaid Grade level was 9.24 ± 2.33 (95% CI 8.78–9.71). The mean Gunning FOG grade was 10.88 ± 3.1 (95% CI 10.26–11.5). The mean Flesch Reading Ease score was 49.88 ± 14.46 (95% CI 46.98–52.78). 7 webpages were at or below the 6th grade reading level. The mean JAMA score was 1.34 ± 1.32 out of 4 (95% CI 1.07–1.6). 14 websites were HONcode accredited.ConclusionThe overall readability of medical information online is too high for the average patient. Given the important role that health literacy provides in patient reported outcomes, improving the readability and quality of these materials is imperative. Awareness by the general public is essential for them to critically appraise the information they receive online.