经皮空心螺钉加压固定踝关节融合术

 目的 探讨经皮空心螺钉加压固定踝关节融合术的临床疗效。方法 2005年4月至 2010年10月,12例单侧严重踝关节炎患者(Kellgren-Lawrence III级)接受经皮空心螺钉加压固定踝关节融合术。男7例, 女5例; 年龄25~71岁, 平均 42.0岁。病程 1~21年,平均 7.3年。类风湿关节炎 2例,创伤性关节炎 8例,骨关节炎2例。取踝关节前正中入路,暴露踝关节腔, 完整去除胫距关节软骨面, 暴露软骨下骨。从后上向前下经皮穿针,以空心螺钉加压固定胫距关节。手术前后采用美国足踝外科医师协会(American Orthopaedic Foot and Ankle Society, AOFAS)踝-后足功能评分进行功能评定,摄踝关节正侧位及踝穴位 X线片观察踝关节骨性融合情况。 结果 12例患者均得到随访,随访时间 6耀55个月,平均 21.5个月。 AOFAS踝-后足功能评分由术前(42.8±8.6)分增加至术后 6个月(66.6±5.4)分,差异有统计学意义(t=-3.075,P=0.012); 末次随访(72.3±4.6)分,与术前比较差异有统计学意义(t=-8.595,P= 0.006)。 X线片证实全部病例均骨性融合,融合时间 9耀21周,平均 13.5周。无感染,无局部皮肤坏死,无螺钉松动、退钉及断钉。结论 经皮空心螺钉加压固定踝关节融合术创伤小,融合率高,融合时间短,近期疗效满意,并发症少。     

Primary stability of shoulder arthrodesis using cannulated cancellous screws

There are no biomechanical studies available concerned with the primary stability of shoulder arthrodesis. The aim of our biomechanical investigations was to ascertain a minimal material combination with high primary stability for shoulder arthrodesis. For that purpose, the primary stability of 6 different forms of screw arthrodesis was investigated under the stress of abduction, adduction, anteversion, and retroversion. The mean values of the screw arthrodeses were compared with those of a 16-hole plate arthrodesis. All tests were carried out on 24 human specimens without destruction by use of a materials testing machine. The most stable form of screw arthrodesis for the load directions of abduction, adduction, anteversion, and retroversion results from a specific configuration of screws comprising 3 horizontal humeroglenoid screws and 3 vertical acromiohumeral screws (318.5 +/- 99.0 N). For three forms of arthrodesis, each with 3 humerus-glenoid screws (299.9 +/- 95.4 N), no significant difference (P = .530) was found compared with a 16-hole plate arthrodesis (293.4 +/- 89.3 N). The plate arthrodeses only achieved higher power values on abduction and adduction stress in comparison with screw arthrodesis with 3 humerus-glenoid screws. The difference was insignificant. Because arthrodesis with 3 humerus-glenoid screws was significantly more stable on stress of anteversion and retroversion, this particular screw arthrodesis is considered superior to plate arthrodeses. The use of the most stable form of screw arthrodesis may reduce nonunion.     

A biomechanical comparison of scaphoid screws

The compressive forces generated by various scaphoid screws were measured in the laboratory using a custom designed load washer (transducer) as a means to compare their fixation capabilities. Testing was done using simulated bones fabricated from polystyrene pipette tubing and Pedilen polyurethane foam and paired cadaver scaphoids. The Herbert scaphoid screw was found to have inferior fixation capabilities compared with screws of a more conventional design. However, its size compatibility was the best of all the screws tested. The Heune scaphoid screw demonstrated the best fixation capability, but was found to be too large for routine use. The ASIF cancellous screw (4.0 mm) demonstrated excellent fixation capability, but was believed to have too large a head size for many scaphoids. An optimal screw design is proposed for use in scaphoid fractures based on failure data for various thread sizes and head diameters.     

Technique for removal of cannulated screws

Cannulated screws can become incarcerated or stripped during the process of initial open-reduction internal fixation or at the time of hardware removal. In addition, many different sizes and brands of cannulated screws exist, and the appropriate size or type of screwdriver may not be available. We describe a simple technique for cannulated screw removal that works for all types of screws and can be performed percutaneously using only a Steinmann pin and T- handle chuck or pin driver.     

Optimum configuration of cannulated hip screws for the fixation of intracapsular hip fractures: a biomechanical study

The radiographs of a sample of patients who had canulated hip screw fixation for intracapsular femoral neck fractures were reviewed in our region. There were six different types of configurations used in these fixations which are divided into two groups: (I) triangular configurations, consisting of two parallel screws with a third screw placed either superiorly, inferiorly, anteriorly or posteriorly; and (II) linear configurations with two or three screws in a vertical line. In our study, we tested the relative strength of each configuration in a laboratory setting using synthetic bone models. Statistical analysis, at 5% significance level, using two-way ANOVA and post-hoc test was carried out to test the differences of the results between the configurations.Our results clearly show that the triangular configurations had a higher peak load, higher ultimate load, less displacement and more energy absorption before failure than other configurations.     

空心螺纹钉治疗股骨颈骨折的滑动加压原理

目的　探讨空心螺纹钉治疗股骨颈骨折的生物力学原理及应用中常见的问题。方法　对AO空心螺纹钉内固定 33例股骨颈骨折进行回顾性研究。按滑动加压的原则 ,根据术后X线片显示的空心螺纹钉排列位置将所有病例分为两组 :符合滑动加压原则的为Ⅰ组共 2 4例 ,要求螺钉位置互相平行 ,所有螺纹完全位于近端骨折块内 ;不符合滑动加压原则的为Ⅱ组共 9例。比较两组治疗效果。结果　所有病例皆获得随访 ,随访时间为 5～ 34个月 (平均 2 4个月 )。根据X线片评价骨折愈合效果。Ⅰ组 2 0例完全恢复骨折前结构 ,4例发生股骨头坏死 (均为头下型骨折 ) ,无骨折不愈合及畸形愈合。Ⅱ组仅 2例完全恢复骨折前结构 ,5例发生股骨头坏死 (其中 4例螺钉穿出股骨头 ) ,3例发生螺钉断裂。Ⅰ组骨折愈合情况明显优于Ⅱ组 (P <0 0 1)。结论　滑动加压是空心螺纹钉治疗股骨颈骨折的生物力学基础 ,内固定操作必须遵循这一原理。     

三枚空心拉力螺钉经皮治疗股骨颈骨折

目的通过研究三枚空心拉力螺钉经皮治疗股骨颈骨折临床操作方法,手术前后注意事项,达到提高临床疗效,减少股骨颈骨折的并发症.方法本组41例均为新鲜股骨颈骨折,经术前牵引复位,在牵引状态及C型臂机透视下,从患肢大腿外侧穿刺,与股骨成20°～30°角的方向交叉钻入导引针,定位正确后,再分别拧入3枚空心拉力螺钉.结果随访2年2个月～13年2个月,采用北京积水潭医院疗效评定标准,41例中愈合39例,愈合率95.12%,发生股骨头缺血性坏死6例,占14.63%.结论术前良好的复位,术中选择合适的螺钉,正规的操作,是手术成功的关键,骨折愈合的基础.术后早期不负重,正确的康复锻炼是降低股骨头缺血性坏死发生率的必备条件.     

Complications of midfoot and hindfoot arthrodesis

Midfoot and hindfoot arthrodeses traditionally have been done to treat deformities resulting from paralytic disorders, residual clubfoot deformity, and posttraumatic arthritis. The surgical indications for midfoot and hindfoot arthrodeses more recently have been expanded to include painful arthritic deformities associated with neuroarthropathy, seropositive or seronegative arthropathies, and neurologic disorders. Regardless of the joint fused or the technique used, the goal of each remains similar: the creation of a painless, plantigrade foot capable of being fitted into, at the very least, a custom shoe. The aim of the current study is to describe the major complications associated with midfoot and hindfoot fusions in adults, and the prevention and the treatment of these complications.     

Subtalar arthrodesis for flexible hindfoot deformities in children

Flexible hindfoot valgus deformities in 16 patients (20 feet) with poliomyelitis and 10 patients (16 feet) with cerebral palsy were surgically treated by a modified Dennyson-Fulford operation using a fibular dowel and a screw. The correction achieved was assessed clinically and radiologically after a mean follow-up of 3.6 years. Overall good results were achieved in 86%. There were no cases of under- or over-correction, pseudarthrosis or screw failure. The procedure is suitable even for spastic planovalgus deformities. Complications related to screw position can be avoided by following the recommendations given here. Use of fluoroscopy and cannulated screws facilitate quick and easy completion of the procedure. Received: 9 August 1996     

股骨颈骨折2枚空心螺钉内固定的力学稳定性研究

目的:分析2枚和3枚空心螺钉固定不同骨折线方向的股骨颈骨折的力学稳定性,为2枚空心螺钉临床应用及其适应证的选择提供理论依据。方法:采集15具国人股骨尸体标本,构建3种Pauwels角(30°、50°和70°)的股骨颈骨折模型,分别行3枚及2枚空心螺钉内固定,采用生物力学检测仪分别测定抗张位移、竖向位移、剪切位移、综合位移、缝隙距、扭矩和刚度值,评价2枚和3枚空心螺钉内固定的力学稳定性。结果:Pauwels角为30°和50°时,2枚空心螺钉内固定的抗张位移、竖向位移、剪切位移、综合位移、缝隙距、扭矩和刚度值与3枚空心螺钉内固定相比较,差异无统计学意义(P0.05);当Pauwels角为70°时,采用3枚空心螺钉内固定后,其力学稳定性优于2枚螺钉内固定,差异有统计学意义(P0.05),同时发现Pauwels角为70°时,即使采用3枚空心螺钉内固定,其力学稳定性明显较Pauwels角为30°和50°时差。结论:Pauwels角为30°和50°时,2枚空心螺钉内固定与3枚空心螺钉内固定的力学稳定性相同,2枚空心螺钉内固定已能较好地维持股骨颈骨折的稳定。而当Pauwels角为70°时,3枚空心螺钉内固定力学稳定性则优于2枚空心螺钉内固定,但其力学稳定性较Pauwels角为30°和50°时弱,手术时需采用角稳定系统或者加用抗滑螺钉以增强骨折内固定的稳定性。     

经皮空心螺钉固定治疗骶骨骨折

目的 探讨经皮空心螺钉固定治疗骶骨骨折的疗效.方法 采用经皮空心螺钉固定治疗骶骨骨折12例.结果 12例均获随访,时间6~24个月,术后3~4个月骨折线均消失,6例骶神经损伤患者4例完全恢复,2例部分恢复.结论 经皮空心螺钉固定骶骨骨折手术有风险,对术者要求较高,但符合微创治疗的发展趋势,且效果良好.     

经骶骨纵向固定腰骶滑脱的解剖学研究

目的　对骶骨进行形态学测量 ,研究后路空心钉经骶骨纵向固定腰骶部的安全性。方法　对 2 0例干燥骶骨标本进行CT扫描 ,并进行多平面重建 (MPR)分析 ,测量S1水平骶骨侧块中心的长、宽及面积 ,确定该固定方法的空心钉钉道的长度、安全方向和范围。结果　 2 0例骶骨标本中 ,该固定方法的最窄部分位于S1神经孔水平 ,其几何中心的平均长度为 (37.31± 4 .2 1)mm(2 9～ 4 6 .7mm) ,平均宽度为 (2 1.2 9± 3.5 7)mm(16 .3～ 2 7.4mm) ,平均面积为 (6 .31± 1.2 3)cm2 。通过测量和分析 ,空心钉在矢状面和冠状面的平均最小角度分别为 2 6 .2 9°(2 4 .1°～ 31.3°)和 4 3.6 5°(2 6 .0°～ 5 4 .5°) ,空心钉的平均长度为 85 .2 8mm。结论　相关解剖学数据表明 ,只要进钉的方向及角度正确 ,空心钉经骶骨纵向固定的通道位于骶骨内。术前行CT检查或三维重建 ,制定个体化固定方案 ,该方法可安全地应用于临床。     

Evaluation of compression in intramedullary hindfoot arthrodesis

Compression was evaluated in an intramedullary hindfoot arthrodesis cadaver model using an external fixator and a "second generation" intramedullary compression nail. Four cadaver specimens were used. Four trials were done with each specimen. Trial 1: manual compression with the 1st generation nail. Trial 2: external fixator for compression with the 1st generation nail. Trial 3: external fixator for compression with the 2nd generation nail. Trial 4: nail-mounted compression device with the 2nd generation nail. In Trial 1 it was not possible to obtain or maintain compression. In Trial 2 large values of compression were obtained with the external fixator, however compression was not maintained after the first generation nails were locked and the fixator was removed. In Trial 3 large values of compression were obtained with the external fixator, but minimal compression was maintained after the second-generation nails were locked and the fixator was removed. In Trial 4 large values of compression were obtained with the compression device and greater than 60% of the compression was maintained after the nail was locked and the compression device was released. The study revealed that both the external fixator and the compression device could produce compression. The external fixator is useful as an aid in the O.R. However, in this study significant compression was maintained only with utilization of the compression device.     

Tibiocalcaneal arthrodesis for the management of severe ankle and hindfoot deformities

PURPOSE: The purpose of this investigation was to evaluate the outcome of tibiocalcaneal arthrodesis using an adolescent condylar blade plate for severe ankle and hindfoot deformities. MATERIALS AND METHODS: We retrospectively reviewed the records of patients managed at our institutions between 1989 and 1996 whose tibiocalcaneal arthrodeses were performed with adolescent condylar blade plates and allograft bone. In these 30 patients (14 men, 16 women; average age, 53 years), the etiologies of the nonbraceable deformity included: diabetic neuroarthropathy with talar fragmentation and resorption (26), inflammatory arthritis (3), and posttraumatic avascular necrosis of the talus with collapse (1). Due to the severity of the deformity in 28 of these patients, the alternative treatment would have been amputation. Thirteen patients had undergone previous surgeries, eight had documented osteomyelitis, and 13 had ulcers ranging from 2 to 27 mm. At surgery, the remnants of the talus were removed. Morcellized bone graft mixed with tobramycin/vancomycin powder was inserted into the arthrodesis site and then fixed with a rigid plate. Intravenous antibiotics, followed by oral antibiotics, were given until wound healing and suture removal. Follow-up averaged 48 months (19 to 112 months). RESULTS: Tibiocalcaneal fusion was achieved in 28/30 patients at an average of 16 weeks (12 to 18 weeks). Complications occurred in seven patients: two developed stress fractures of the tibia at the proximal end of the blade plate, three had superficial cellulitis that resolved with antibiotic therapy, and two had nonunions. CONCLUSION: Tibiocalcaneal arthrodesis using an adolescent condylar blade plate and allograft bone can be a successful procedure in the patient with severe neuropathic ankle deformity and can achieve a stable plantigrade foot for limited community ambulation with relatively few complications.     

颈椎经关节椎弓根螺钉固定与标准椎弓根螺钉固定的生物力学比较

目的 比较颈椎经关节椎弓根螺钉固定和标准椎弓根螺钉固定的拔出强度.方法 取10具新鲜尸体颈椎标本(C_3～T_1),游离成三个颈椎运动节段(C_(3,4),C_(5,6),C_7T_1).在椎体两侧随机进行经关节椎弓根螺钉固定或标准椎弓根螺钉固定,置入直径3.5 mm皮质骨螺钉.经关节椎弓根螺钉固定以上位椎骨侧块外下象限中点为进钉点,在直视椎弓根下,螺钉在冠状面内倾约45°、矢状面尾倾约50°.由上位椎骨下关节突经关节突关节、下位椎骨的椎弓根,进入下位椎骨的椎体内.标准椎弓根螺钉固定以侧块外上象限中点为进钉点,在直视椎弓根下,螺钉方向参考CT测量结果 ,尽量与椎弓根倾斜角度保持一致,在横断面上内倾约45°、矢状面上螺钉指向椎体的上1/3.在生物力学试验机上行拔出强度试验,比较两种螺钉固定的最大轴向拔出力.结果 颈椎经关节椎弓根螺钉固定平均最大轴向拨出力为(694±42)N,标准椎弓根螺钉固定为(670±36)N,两者比较差异有统计学意义(P<0.05).结论 颈椎后路经关节椎弓根螺钉固定的拔出强度大干标准椎弓根螺钉固定,从生物力学强度方面考虑经关节椎弓根螺钉固定可以作为标准椎弓根螺钉固定的一种补充方法.     

颈椎经关节椎弓根螺钉固定与标准椎弓根螺钉固定的生物力学比较

Objective To compare biomechanical pullout strength of cervical transfacet pedicle screws to that of standard pedicle screws. Methods Ten fresh human cadaveric cervical spines were harvested. On one side, transfacet pedicle screws were placed at the C3,4, C5,6, and C7T1 levels. On the other side, pedicle screws were, placed at the C3, C5, and C7 levels. The screw insertion technique at each level was randomized for right or left. The starting point for the transfacet pedicle screw insertion was about located at the midpoint of the inferolateral quadrant of the lateral mass and the direction of the screw was about 50° caudally in the sagittal plane and about 45° medially in the axial plane. Screws were placed across the facet joint and the pedicle into the body of the caudal vertebra. The entry points for pedicle screw was located at the midpoint of the superolateral quadrant of the lateral mass and the direction of the screw was about 45° toward the midline in the transverse plane and toward the upper third of the vertebral body in the sagittal plane. The pedicle screws were oriented along the axis of the pedicle in an effort to avoid violations of the cortical wall. All the screw insertions were based on direct observation and the CT scan on the pedicles. After screw placement, axial pullout testing was performed. Results The mean pullout strength for the transfacet pedicle screws was (694±42) N. This compares with (670±36) N for the pedicle screws (P< 0.05). The greatest difference at a single level in pullout strength was observed at the C5,6 level, with a mean difference of 38 N. Conclusion Transfacet pedicle screws exhibited statistically greater pullout strength to pedicle screws. At each level the transfacet pedicle screws exhibited greater pullout strength than the pedicle screws. Posterior transarticular pedicle screw fixation in the cervical spine affords an alternative to standard screw placement for plate fixation and cervical stabilization.     

A biomechanical study of simulated femoral neck fracture fixation by cannulated screws: effects of placement angle and number of screws

The angle of placement of hip screws to fix femoral neck fractures is still a controversial subject, and it must be addressed. In the study reported here, we compared the relative stiffness of fixation of simulated Pauwels type III femoral neck fractures fixed with either 2 or 3 cannulated screws implanted at 135 degrees, 145 degrees, and 150 degrees. Each femur was fixed with 2 or 3 cannulated screws and tested under axial loading and anteroposterior (AP) bending. Then each femur was fatigued to 1000 cycles and tested to failure. Fourteen femurs were tested. Results showed that axial stiffness values were not statistically different at different angles. AP bending stiffness of the high-angle (150 degrees) construct was significantly higher than that of either of the other 2 constructs (for 2 screws only). Two-screw fixation appears to be adequate; adding a third screw may not be necessary.