C_2椎弓根螺钉固定治疗Hangman fracture的护理

目的 :C2 椎弓根螺钉固定治疗Hangmanfracture的护理。方法 :对 10例病人术前做好心理护理 ,呼吸功能训练以及康复 ,体位的训练 ,术后重视了体位护理 ,生命体征以及引流 ,伤口的观察 ,并注意预防术后并发症。结果 :6例病人均获得不同程度的恢复 ,未发生护理并发症 ,并获及随访。结论 :C2 椎弓根螺钉治疗Hang manfracture手术复杂 ,风险大 ,而科学护理是提高手术成功率 ,减少并发症的重要保证。

Min-invasive surgical treatment for multiple axis fractures: A case report

BACKGROUND Fractures of the axis are commonly seen in spinal injuries. Upper cervical fractures are usually managed conservatively. However, the complications due to long-term external immobilization cannot be ignored. The traditional open surgery has the disadvantages of too much blood loss and soft tissue injury. The aim of our paper is to introduce a minimally invasive surgical treatment for multiple axis fractures.CASE SUMMARY We report a 40-year-old Chinese male who had severe neck pain and difficult neck movement after falling from 3 meters. X-ray and computed tomography(CT) scan revealed an axis injury consisting of an odontoid Type Ⅲ fracture associated with a Hangman fracture categorized as a Levine-Edwards Type Ⅰ fracture. The patient underwent anterior odontoid screw fixation and posterior percutaneous screw fixation using intraoperative O-arm navigation. Neck pain was markedly improved after surgery. X-rays and CT scan reconstructions of 3-mo follow-up showed good stability and fusion. The range of cervical motion was well preserved.CONCLUSION Anterior odontoid screw fixation and posterior direct C2 percutaneous pedicle screw fixation with the aid of O-arm navigation and neurophysiological monitoring can be an interesting alternative option for complicated multiple axis fractures.

Comparison of the modified Wiltse’s approach with spinal minimally invasive system and traditional approach for the therapy of thoracolumbar fracture

Thoracolumbar fractures are usually treated by open posterior pedicle screw fixation.However,this procedure involves massive paraspinal muscle stripping,inflicting surgical trauma,and prolonged X-ray exposure.In this study,we observed 127 patients with single-segment injury thoracolumbar fractures.Thirty-six patients were treated by the modified Wiltse’s paraspinal approach with minimally invasive channel system,while 91 patients were treated via traditional posterior approach.Operation time,intraoperative blood loss,intraoperative fluoroscopy frequency,screw placement accuracy,visual analogue scale score,and Cobb’s angle of two groups were compared.The X-ray exposure times were notably reduced(4.2±1.6) in the new approach group(P<0.05).The pedicle screw placement accuracy and Cobb’s angle after surgery were similar in the two groups.We conclude that modified Wiltse’s paraspinal approach w ith spinal minimally invasive channel system surgery can significantly reduce the X-ray exposure times and is an alternative therapy for the thoracolumbar fracture.

Experimental study on the e ect of fracture scale on seismic wave characteristics

In fractured reservoir beds, fracture characteristics affect seismic wave response. Fractured models based on the Hudson＇s fractured medium theory were constructed in our laboratory by a backfilling technique. For the same fracture density, the variations of the velocity and amplitude of the primary wave and shear wave parallel and perpendicular to the fracture were observed by altering the diameter （scale） of the penny-shaped fracture disk. The model test indicated that an increase of fracture scale increased the velocity and amplitude of the primary wave by about 2%. When the shear wave propagated parallel to the fracture, the velocity of the fast shear wave hardly changed, while the velocity of slow shear wave increased by 2.6% with increasing fracture scale. The results indicated that an increase of fracture scale would reduce the degree of anisotropy of the shear wave. The amplitudes of slow shear waves propagating parallel and perpendicular to fractures decreased with increasing fracture scale.

Bennett's fracture associated with fracture of Trapezium——A rare injury of first carpo-metacarpal joint

Association of fracture of trapezium with Bennett'sfracture is very rare and makes reduction and stabilisation more difficult. We are reporting a rare case of Bennett's fracture with fracture of the trapezium and subluxation of the carpo-metacarpal joint(CMC) joint. The patient was a 47-year-old school teacher who fell from his motorbike on his outstretched right dominant hand. Radiographs and computed tomography showed fracture of the trapezium with subluxation of the CMC joint, associated with Bennett's fracture. Open reduction and internal fixation was carried out. Trapezium was reduced first and secured with a 2 mm diameter screw. Bennett's fracture was then reduced and fixed with two per-cutaneously placed Kirchner's wires. CMC was stabilised with percutaneous Kirchner's wires. Latest follow up at 12 mo showed a healed fracture with good reduction of the CMC joint. Clinically patient had no pain and normal extension, abduction and opposition of the thumb. QuickD ASH score was 3.9/100. Thus, fracture of trapezium associated with a Bennett's fracture is a rare injury and if ignored it may lead to poor results. This injury is more challenging to manage than an isolated Bennett's fracture as anatomical reduction of the trapezium with reduction of the first CMC is needed. Fracture of the trapezium should be fixed first as this will provide a stable base for reduction of the Bennett's fracture.

Strategy for prevention of hip fractures in patients with Parkinson's disease

Hypovitaminosis D and K due to malnutrition or sunlight deprivation,increased bone resorption due to immobilization,low bone mineral density(BMD)and an increased risk of falls may contribute to an increased risk of hip fractures in patients with Parkinson’s disease.The purpose of the present study was to clarify the efficacy of interventions intended to prevent hip fractures in elderly patients with Parkinson’s disease.Pub Med was used to search the literature for randomized controlled trials(RCTs)regarding Parkinson’s disease and hip fractures.The inclusion criteria were 50 or more subjects per group and a study period of 1 year or longer.Five RCTs were identified and the relative risk and95%confidence interval were calculated for individual RCTs.Sunlight exposure increased serum hydroxyvitamin D[25(OH)D]concentration,improved motor function,decreased bone resorption and increased BMD.Alendronate or risedronate with vitamin D supplementation increased serum 25(OH)D concentration,strongly decreased bone resorption and increased BMD.Menatetrenone(vitamin K2)decreased serum undercarboxylated osteocalcin concentration,decreased bone resorption and increased BMD.Sunlight exposure(men and women),menatetrenone(women),alendronate and risedronate with vitamin D supplementation(women)significantly reduced the incidence of hip fractures.The respective RRs(95%confidence intervals)according to the intention-to-treat analysis were 0.27(0.08,0.96),0.13(0.02,0.97),0.29(0.10,0.85)and 0.20(0.06,0.68).Interventions,including sunlight exposure,menatetrenone and oral bisphosphonates with vitamin D supplementation,have a protective effect against hip fractures elderly patients with Parkinson’s disease.

Outcome of application of primary versus secondary Illizarov＇s fixator in open tibial shaft fractures

BACKGROUND: The present study aimed to compare outcome of primary and secondary Illizarov's fi xator application as a treatment method for type III open tibial fractures in terms of nonunion and wound infection.METHODS: This prospective study was done in a tertiary care center. Forty-eight type III tibial fractures were treated with Illizarov's apparatus between 2008 and 2011. The patients were divided into two groups depending on the treatment protocol, timing of wound closure and Illizarov's application, primary(n=28) and secondary(n=20).RESULTS: In the primary group, healing was achieved in all 28 patients. The median time to recovery was 24 weeks, and the median number of operations was 3. There were 6 patients with a bone defect. In the secondary group, complete recovery was achieved in 18 out of 20 patients. The median time to recovery was 30 weeks, and the median number of operations 5. There were 9 patients with a bone defect. The median time to recovery and the number of operations were signifi cantly smaller in patients undergoing primary operation. Union was 100% in the primary group and more than 95% in the secondary group. Chronic osteomyelitis persisted in one patient and below amputation was done in one patient in the secondary group.CONCLUSION: Primary wound closure and Illizarov's fixation required a smaller number of operations and shorter time to recovery than secondary wound closure and Illizarov's fi xation, mostly due to a signifi cantly less number of patients with a bone defect in the primary group.

后路钉棒固定不植骨与植骨融合治疗不稳定Hangman骨折的疗效比较

目的:比较后路钉棒固定不植骨与后路钉棒固定植骨融合治疗不稳定Hangman骨折的疗效。方法:回顾性分析2014年1月~2020年12月在我院接受颈后路钉棒内固定手术且随访2年以上的39例不稳定Hangman骨折患者的临床及影像学资料,平均随访3.2±1.9年(2~9年)。男性31例,女性8例,年龄43.1±16.1岁(13~70岁)。其中22例接受单纯后路钉棒固定术(不植骨组:A组),17例接受后路钉棒固定自体髂骨植骨融合术(植骨组:B组)。记录并比较两组患者手术时间、术中出血量、术后并发症,术前、术后1周、术后3个月及末次随访时疼痛视觉模拟评分(VAS),术前、术后3个月及末次随访时颈椎功能障碍指数(NDI),术前及末次随访时美国脊髓损伤协会(ASIA)脊髓损伤分级,末次随访时Odom′s分级。在术前、术后1周及末次随访时颈椎侧位X线片上测量并比较两组间C2/3移位、成角和颈椎前凸角,颈椎正侧位X线片及三维CT上观察骨折愈合情况、C2/3后方关节突关节(小关节)、椎体间融合情况。结果:39例患者均顺利完成手术。手术时间A组99.3±14.2min,B组137.9±19.5min;术中出血量A组94.6±12.6mL,B组140.6±17.8mL,A组比B组手术时间更短,术中出血量更少(P<0.05)。A组2例术后发生浅表切口感染,B组1例术后发生浅表切口感染、4例供骨区疼痛,予以对症处理后均好转。两组患者术后1周、术后3个月及末次随访的VAS评分和术后3个月及末次随访的NDI较术前明显改善(P<0.05),两组间各随访时间点比较无统计学差异(P>0.05)。末次随访时两组患者ASIA分级及Odom′s分级无统计学差异(P>0.05)。两组患者术后1周及末次随访时C2/3成角、移位及颈椎前凸角较术前显著性改善(P<0.05),两组间各随访时间点上述指标比较无统计学差异(P>0.05)。末次随访时,39例患者骨折全部愈合良好。A组C2/3双侧小关节均自发融合,椎体前缘自发融合1例,椎体后缘自发融合9例,椎体前缘和后缘均自发融合4例;B组C2/3双侧小关节均骨性融合,椎体前缘自发融合0例,椎体后缘自发融合10例,椎体前缘和后缘均自发融合3例;末次随访时,两组C2/3小关节(全部融合)和椎间融合率(A组63%、B组76%)无统计学差异(P>0.05)。结论:后路钉棒固定不植骨和后路钉棒固定植骨融合治疗不稳定Hangman骨折均能够获得满意的临床疗效,术后C2/3小关节及椎体间融合率相似。不植骨能明显缩短手术时间、减少术中出血、避免取髂骨相关并发症。

Effect of Plastic Deformation and H_2S on Dynamic Fracture Toughness of High Strength Casing Steel

The effects of plastic deformation and H2 S on fracture toughness of high strength casing steel（C110 steel） were investigated. The studied casing specimens are as follows： original casing, plastic deformation（PD） casing and PD casing after being immersed in NACE A solution saturated with H2S（PD＋H2S）. Instrumented impact method was employed to evaluate the impact behaviors of the specimens, meanwhile, dynamic fracture toughness（JId） was calculated by using Rice model and Schindler model. The experimental results show that dynamic fracture toughness of the casing decreases after plastic deformation. Compared with that of the original casing and PD casing, the dynamic fracture toughness decreases further when the PD casing immersed in H2 S, moreover, there are ridge-shaped feature and many secondary cracks present on the fracture surface of the specimens. Impact fracture mechanism of the casing is proposed as follows： the plastic deformation results in the increase of defect density of materials where the atomic hydrogen can accumulate in reversible or irreversible traps and even recombine to form molecular hydrogen, subsequently, the casing material toughness decreases greatly.

后路C_(2-3)固定结合顶棒置入与单纯后路C_(2-3)固定治疗不稳定Hangman骨折的比较

背景:Hangman骨折中Ⅱ、ⅡA、Ⅲ型常需手术治疗,手术方式选择存在较大争议,目前均存在术后复位不全及畸形愈合等不足;前期作者团队使用C_(2-3)拉力螺钉结合经口顶棒技术间歇性推顶C2椎体治疗不稳定Hangman骨折,取得了满意的临床疗效,但前期研究样本少,且缺少对照组比较。目的:比较后路C_(2-3)固定结合经口顶棒技术和单纯后路C_(2-3)固定治疗不稳定Hangman骨折的临床疗效。方法:回顾性分析西南医科大学附属医院收治的行后路C_(2-3)固定手术治疗的55例不稳定Hangman骨折患者临床及影像学资料,根据手术方案分为2组,其中23例患者接受后路C_(2-3)固定结合经口顶棒技术治疗(A组),32例接受单纯后路C_(2-3)固定术(B组)。比较两组患者的手术时间、术中出血量、并发症、术前及末次随访时疼痛目测类比评分、颈椎功能障碍指数、美国脊髓损伤协会脊髓损伤分级和患者满意度(Odom’s分级);另外对比各观察时间点C_(2-3)移位和成角及其他影像学指标的变化。结果与结论:①两组患者手术时间、术中出血量和术后并发症发生情况比较差异无显著性意义(P>0.05);②两组患者末次随访颈痛目测类比评分和颈椎功能障碍指数较术前获得显著改善(P<0.05),Odom’s分级显示A组优良21例(91%);B组优良29例(91%);两组各项临床疗效指标比较差异均无显著性意义(均P>0.05);③两组术前C_(2-3)成角和位移差异无显著性意义(P>0.05);术后及末次随访时,两组患者C_(2-3)成角和位移均较术前明显减小,差异有显著性意义(P<0.01);术后和末次随访上述指标比较差异无显著性意义(P>0.05);术后及末次随访时,A组C_(2-3)位移和成角较B组明显减小,差异有显著性意义(P<0.05);④末次随访时,A组患者均未发生残余畸形,B组发生残余畸形4例(13%,4/32);⑤因此,后路C_(2-3)固定结合经口顶棒技术可能有利于枢椎体复位和稳定,减少畸形愈合,获得更好的复位。

扭紧力矩对SWRM10K螺栓疲劳性能影响的研究

对扭紧力矩分别为0、12.5、22.0、29.5和35.0 Nm的SWRM10K钢螺栓进行轴向加载疲劳实验,获取螺栓的疲劳S-N数据。对比不同扭紧力矩下螺栓疲劳S-N特性,分析扭紧力矩对螺栓疲劳性能的影响。采用SEM观察螺栓试样的断口形貌,结合EDS分析裂纹萌生区元素分布,揭示螺栓疲劳断裂的规律。研究结果表明:增加扭紧力矩能有效提升该螺栓疲劳极限,但增加到一定程度提升效果明显下降,扭紧力矩值接近29.5 Nm较为合理。在该扭紧力矩下,螺栓疲劳极限为141 MPa,与未施加扭紧力矩相比提升了62.1%。螺栓疲劳断口分为3个区域:裂纹萌生区、扩展区和瞬间断裂区。在高应力幅下,裂纹萌生于试样表面,由晶体滑移引起;在低应力幅下,裂纹同样萌生于试样表面,但由晶体滑移或夹杂物引起。

High-cycle Fatigue Fracture Behavior of Ultrahigh Strength Steels

The fatigue fracture behavior of four ultrahigh strength steels with different melting processes and therefore different inclusion sizes were studied by using a rotating bar two-point bending fatigue machine in the high-cycle regime up to 107 cycles of loading. The fracture surfaces were observed by field emission scanning electron microscopy （FESEM）. It was found that the size of inclusion has significant effect on the fatigue behavior. For AtSI 4340 steel in which the inclusion size is smaller than 5.5 μm, all the fatigue cracks except one did not initiated from inclusion but from specimen surface and conventional S-N curve exists. For 65Si2MnWE and Aermet 100 steels in which the average inclusion sizes are 12.2 and 14.9 μm, respectively, fatigue cracks initiated from inclusions at lower stress amplitudes and stepwise S-N curves were observed. The S-N curve displays a continuous decline and fatigue failures originated from large oxide inclusion for 60Si2CrVA steel in which the average inclusion size is 44.4 pro. In the case of internal inclusion-induced fractures at cycles beyond about 1×10^6 for 65Si2MnWE and 60Si2CrVA steels, inclusion was always found inside the fish-eye and a granular bright facet （GBF） was observed in the vicinity around the inclusion. The GBF sizes increase with increasing the number of cycles to failure Nf in the long-life regime. The values of stress intensity factor range at crack initiation site for the GBF are almost constant with Nf, and are almost equal to that for the surface inclusion and the internal inclusion at cycles lower than about 1×10^6. Neither fish-eye nor GBF was observed for Aermet 100 steel in the present study.

EFFECTS OF POISSON’S RATIO ON SCALING LAW IN HERTZIAN FRACTURE

In this paper the Auerbach＇s scaling law of Hertzian fracture induced by a spherical indenter pressing on a brittle solid is studied. In the analysis, the singular integral equation method is used to analyze the fracture behavior of the Hertzian contact problem. The results show that the Auerbach＇s constant sensitively depends on the Poisson＇s ratio, and the effective Auerbach＇s domain is also determined for a given value of the Poisson＇s ratio.

Fractures in Parkinson’s Disease

Parkinson’s disease is a neurodegenerative disorder that is common in older people and is highly associated with depression, anxiety, apathy, psychosis, cognitive impairment, imbalance and sleep disturbances. These patients have an increased risk of fracture compared to the general population. Comprehensive searches of databases are performed to identify reviews about the risk of fractures in this disease. Parkinson’s patients are at increased risk for low bone mineral density due to the effect of drugs, Parkinson’s disease and age factor, leading to an increased risk of falling down and fractures, especially in the hip. So, improved and innovative treatments with the focus on minimizing inadvertent bone resorption with anti-Parkinson’s disease medication will be highly effective in reducing fear of the disease and providing the patient with a better quality of life.

Hoffa's fracture in a five-year-old child diagnosed and treated with the assistance of arthroscopy:A case report

BACKGROUND Hoffa’s fracture is a coronal-oriented fracture of the femoral condyle.It is rarely observed in pediatric patients that isolated coronal fracture of the medial femoral condyle accompanies an intact lateral femoral condyle.Only a few cases involving Hoffa’s fracture of the medial femoral condyle have been reported in patients with undeveloped skeletons.Such a fracture cannot be observed by routine imaging examinations,thus resulting in possible misdiagnosis and further treatment challenges.CASE SUMMARY A 5-year-old boy with Hoffa’s fracture of the medial femoral condyle suffered from right knee pain and severe swelling after being hit by a heavy object.The patient was misdiagnosed and initially treated in a local primary healthcare center.No improvement in his right knee’s extension was observed following conservative treatment for 2 wk.The patient was transferred to our hospital,rediagnosed using arthroscopy,and underwent open reduction and internal fixation.The therapeutic outcome was satisfactory with the screws removed 7 mo after fixation.At the final follow-up of 40 mo,the range of motion in the knee had recovered.There was no varus-valgus instability.CONCLUSION Hoffa’s fracture is rarely seen in children aged 5 years,let alone in the medial condyle,and can easily be misdiagnosed due to limited physical and imaging examinations.Suspected Hoffa’s fracture in preschool children should be confirmed based on arthroscopic findings.Open reduction and internal fixation should be performed to protect the articular surface and prevent long-term complications.

Seismic and Tectonic Correspondence of Major Earthquake Regions in Southern Ghana with Mid-Atlantic Transform-Fracture Zones

For four centuries now, southern Ghana has been known to be seismically active, and there is no clear geological explanation for the cause of the seismicity. By evaluating new field data and information with re-interpreted historical earthquake data of southern Ghana, the nature of the seismicity of southern Ghana has been elucidated. The mutual connection between the earthquake epicentres and the remote causes by Mid-Atlantic transform faults and fracture zones has been established. The seismic regions of southern Ghana have been linked separately to tectonic faults and activities of the St. Paul’s and Romanche transform-fracture zone systems offshore in the Gulf of Guinea to onshore. It is concluded that the seismicity of southern Ghana is due to tectonic activities of the St. Paul’s and Romanche transform-fracture systems. The Accra region earthquakes originate from reactivation of faults in the Romanche transform-fracture zone, and propagate onshore through Accra and environs. The Axim region earthquakes come from reactivated faults linked to the St Paul’s fracture zone, which go through southern Cote D’Ivoire to Ghana. Seismotectonic movements along the St Paul’s transform and fracture zones have quieted since 1879. But movement along the Romanche Transform fault and Fracture zone is active, causing ongoing seismicity of southern Ghana.

Fracture Femur in a Case of Pyle’s Disease: A Case Report

Pyle’s disease is a rare genetic skeletal disorder also known as Metaphyseal dysplasia. A case of 36 yrs old female with fracture supracondylar femur in Pyle’s disease is presented. She had mild facial dysmorphism, dental malformation & mild genu valgum. Skeletal radiology revealed the characteristic Erlenmeyer flask sign at distal femoral and proximal tibial metaphysis. The fracture supracondylar femur was treated with interlocking nail. The fracture was united in sixteen weeks period. The patient is followed up for two years. The aim of the case report is the rarity of the condition with fracture supracondylar femur in adult female successfully treated with interlocking nail.

斗南锰矿带成矿地质条件及斗南坝心地区明苏断裂(“S”形断裂)研究新认识与探讨

斗南锰矿带是滇东南地区重要的锰矿成矿带,其在地理位置上与明苏断裂(“S”形断裂)基本重合,成矿带上分布有岩子脚、斗南、大箐、老乌、龙潭等一批大、中型锰矿床;前人对“S”形断裂的专题研究较少,仅仅是从锰矿成矿机制方面进行分析、评价。通过对平远斗南锰矿地区进行矿产地质调查工作,及对坝心地段做地质、物探调查工作,结合对该断裂带相关资料的研究分析,认为“S”形断裂可能在不同区域位置不是实质性的同生断裂,主体表现是推覆断裂的形迹,局部有可能存在推覆断裂与同生断裂在地表重合。同时结合工作中的一些新认识,对锰矿深部成矿地质条件进行梳理总结和探讨,希望对本地区锰矿研究和找矿突破提供有价值的参考。

Comparison between Distractor Application on Both Radial &Ulnar Side and Radial Side Only for Fracture Distal Radius with Ulnar Styloid Fracture

Background: Fracture of distal radius with involvement of the ulnar styloid process is a common clinical problem. It can be treated conservatively, usually involving wrist immobilization in plaster cast or surgically. A key method of surgical fixation is external fixation by distractor. Distractor can be applied either only on the radial side or on both ulnar and radial sides. Materials and Methods: A prospective randomized and comparative study of 1 year duration was conducted on 32 patients admitted in the Department of Orthopaedics of BSMC & H in the age group of 20 to 75 years old with AO types B and C distal radius fracture along with involvement of the ulnar styloid process. The parameters studied were restoration of radial length, restoration of radial angle, intracarpal step-off and palmar tilt which were statistically evaluated and Fisher’s exact test was performed. The two tailed P-value was calculated and both the groups were statistically compared. Results: In our study, 37.5% patients in Group A and 81.25% in Group B had a radial difference Table 1, Chart 1). 43.75% patients in Group A and 87.5% in Group B had radial angle Table 2, Chart 2). 31.25% in Group A and 75% had intra carpal step off Table 3, Chart 3). 62.5% had an abnormal palmar tilt in Group A while only 6.25% had an abnormal palmar tilt in Group B which is extremely statistically significant. On an average, 2 mm of distraction was required in 75% patients of Group A while only 30% patients in Group B required distraction (Table 4, Chart 4). Conclusion: In our study, the radial difference, radial angle, intra carpal step off and palmar tilt returned significantly to normal in the patients treated with distractor on radial side only when compared with distractor application on both radial and ulnar sides for distal radius fracture with ulnar styloid process involvement. Also post-operative distraction required under image intensifier was higher in the group treated with distractor on either side than those with distractor only on radial side.

A retrospective study of unfavorable fractures during sagittal split osteotomy:A single surgeon’s experience

Background:Unfavorable fractures are among the most common complications of bilateral sagittal split ramus osteotomy(BSSRO).This study aimed to evaluate unfavorable fracture patterns during BSSRO and assess the related risk factors and treatment measures.Methods:The clinical records and radiographs of 679 patients(1358 sides)who underwent BSSRO at Shanghai Ninth People’s Hospital between September 2013 and December 2021 were examined.Results:Patients with unfavorable fractures who underwent surgical restoration were studied.The incidence of unfavorable fractures was 0.8%(n¼11),with the highest rate in the third year.The unfavorable fractures were divided into three types by location and clinical treatment:(1)SSRO could still be completed after buccal/lingual plate unfavorable fracture(0.6%,n=8);(2)condylar/coronoid process fractures/intermaxillary fixation needed(0.1%,n=2);(3)additional osteotomy required(0.07%,n=1).Conclusion:These results suggest that as a surgeon’s experience increases,the rate of unfavorable fractures may decrease.The novel classification of unfavorable fractures for SSRO might be useful for surgeons to make appropriate treatment choices during orthognathic surgery.