Hoffa’s fracture in an adolescent treated with an innovative surgical procedure:A case report

BACKGROUND Hoffa fracture is rare,especially in adolescents,and has a high rate of complications such as avascular necrosis and osteoarthritis;moreover,there are no definitive guidelines for its treatment.This report could provide a new potential treatment for Hoffa fracture.CASE SUMMARY A 16-year-old girl presented to the orthopedic emergency department of No.2 People’s Hospital of Yibin City with persistent pain following a right knee injury sustained during a sprint race.Her knee was swollen and tender,and the range of motion was restricted by the pain.X-ray and computed tomography revealed a Hoffa fracture in the right knee.After consultation,surgical treatment was performed,and the fracture was fixed with three 3.5-mm cannulated cancellous screws;osteochondral plugs that were harvested from the screw insertion site were re-implanted to cover the screw head.The patient’s fracture and osteochondral plug healed 6 mo postoperatively,and she presented a knee range of motion of 0–135 without pain,and was walking without support with a normal gait.CONCLUSION Here,we describe an innovative surgical procedure for Hoffa fracture that could provide a new possibility for the treatment of similar fractures,and further improve their management.

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.

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.

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.

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。

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.

Surgical Treatment for Proximal Humerus Fractures Comparison between Plate Fixation and Kapandji’s Pinning

Introduction: Proximal humerus fractures are common, however, there is no consensus on a decision-making algorithm for the therapeutic management of these fractures, the aim of this study is to evaluate and compare functional results between two surgical techniques and to deduce the satisfactory results of the Kapandji’s pinning which, compared to the screw plate, should keep its place in the therapeutic arsenal. Patients and Methods: It’s a retrospective study, including two groups: The first of 18 patients treated with palm-tree pinning using kapandji’s technique, the second of 16 patients treated with anatomical screw plate at the orthopedic trauma service of the Mohamed VI university hospital between July 2013 and July 2018. We compared the results of the two techniques by studying three parameters which are the healing time, the anatomical reduction, and the functional outcomes. The average age was 46 years, and the sex ratio (M/F) was 2.3. Results: The statistical analysis of functional and radiological results showed no significant difference between the two techniques, indeed the average healing time was 56.3 days in the group treated by screw plate and 55.2 days in the group treated by Kapandji’s pinning (p = 0.46), Constant’s score was 73.18 and 79.05 respectively (p = 0.27) and the average cephalodiaphyseal angle was 49.03° and 52.07°, respectively (p = 0.35). Discussion: This study has clearly shown, as reported in the literature, that there is no conclusive evidence to suggest superiority of os-teosynthesis by anatomical plate versus kapandji’s pinning. However, the simple achievement of pinning according to kapandji’s technique, the preservation of soft tissues and the low cost make us prefer this technique. Furthermore, despite the progress noted in the development of osteosynthesis means of the proximal humerus, percutaneous pinning should always keep its place.

臂丛颈丛神经阻滞麻醉联合瑞芬太尼在锁骨骨折中的应用及对OAA/S评分、VAS评分的影响

目的:观察臂丛颈丛神经阻滞麻醉联合瑞芬太尼用于锁骨骨折手术的效果。方法:选取吉安市永丰县中医院2019年1月~2022年11月就诊的锁骨骨折患者140例为研究对象,按照收治的先后顺序随机分为试验组和对照组各70例,对照组予以臂丛颈丛神经阻滞麻醉,试验组在对照组基础上加用瑞芬太尼。记录两组麻醉前(T0)、臂丛颈丛神经阻滞麻醉后15 min(T1)、辅助用药后3 min(T2)、手术开始后5 min(T3)、手术开始后15 min(T4)、手术结束时(T5)的平均动脉压(MAP)、心率(HR)、脉搏血氧饱和度(SpO 2)。同时观察两组期间的不良反应以及血管活性药麻黄碱、阿托品、尼卡地平以及艾司洛尔的例数。比较两组患者麻醉满意度的差异。结果:对照组T2时血压降低、心率减慢均不明显,与T0比较差异无统计学意义(P>0.05)。试验组T3、T4时血压升高、心率增快明显,与T0和对照组比较差异有统计学意义(P<0.05)。试验组T2血压降低、心率减慢明显,与对照组和T0比较差异有统计学意义(P>0.05),随后趋于平稳。试验组血管活性药物尼卡地平以及艾司洛尔的例数少于对照组,差异有统计学意义(P<0.05)。两组视觉模拟评分(VAS)及镇痛效果满意率比较差异有统计学意义(P<0.05)。结论:臂丛颈丛神经阻滞麻醉联合瑞芬太尼用于锁骨骨折切开复位内固定手术,镇静镇痛效果确切,呼吸循环稳定,患者麻醉满意度高,是一种安全、有效的麻醉方法。

可吸收止血绒S-100在骨折内固定手术患者中的应用效果

目的:分析可吸收止血绒S-100在骨折内固定手术患者中的应用效果。方法:回顾性选取2022年3月—2023年6月河南省胸科医院收治的106例骨折内固定手术患者作为研究对象。根据可吸收止血绒S-100的使用情况将其分为对照组和观察组,各53例。对照组术中采用气囊止血带止血,观察组术中采用可吸收止血绒S-100。比较两组围手术期指标,引流量及引流管拔管时间,术前及术后第3天凝血功能。结果:观察组手术时间及住院时间均短于对照组,术中出血量少于对照组,差异有统计学意义(P<0.05)。观察组术后24 h、48 h引流量少于对照组,引流管拔管时间短于对照组,差异有统计学意义(P<0.05)。术后第3天,两组凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)均降低,纤维蛋白原(FIB)及D-二聚体(D-D)均明显升高,观察组PT及APTT均高于对照组,FIB及D-D均低于对照组,差异有统计学意义(P<0.05)。结论:可吸收止血绒S-100应用在骨折内固定手术中止血效果显著,能减少局部渗出,缩短引流周期,对患者凝血功能影响较小。

Clinical significance of Baumann's angle in the percutaneous pinning fixation for supracondylar fractures of the humerus in children

To evaluate the clinical significance of Baumann’s angle in the closed reduction and percutaneous pinning fixation for supracondylar fractures of the humerus in children.Methods There were 97 children (male 59,female 38,mean age of 6.8 years) with displaced supracondylar fracrtures of the humerus were treated in this hospital.Under fluoroscopy guidance,three-dimensional displacement of fractures was corrected by closed reduction.The percutaneous Kirschner wire pinning was applied only if the radiographs demonstrated that Baumann’s angle was less than 4 degree compared to that on the normal side.All of them were followed up for 34.5 months (range,12 to 48 months).Results There was one case with ulnar nerve palsy associated with the pinning.There were no Volkmann’s contracture in this group.X-ray examinations revealed an average 73.7 degrees of Baumann angle on the injured and 72.8 on uninjured side.An average 7.6 degrees of the carrying angle on the injured and 9.7 on uninjured side were also demonstrated by radiography.Five patients developed slight cubitus varus deformity.The result according to Flynn criteria were excellent in 85 patients (87.6%),good in 12 patients (12.4%).Conclusion The satisfactory results can be gained in children with displaced supracondylar fractures of the humerus by restoration of the normal Baumann angle and percutaneous pinning fixation.18 refs,2 figs.

经皮微创、Wiltse间隙微创入路与传统切开后入路治疗老年胸腰椎骨折临床疗效

目的探讨经皮微创、Wiltse间隙微创及传统切开后入路联合伤椎椎弓根内固定术治疗老年胸腰椎骨折的临床效果。方法回顾性分析2018年3月至2021年12月诊断为胸腰椎骨折的老年患者98例的临床资料。根据手术入路的不同,将患者分为经皮组、Wiltse组和切开组,经皮组31例,其中男14例,女17例。平均年龄(69.3±6.6)岁;Wiltse组33例,男12例,女21例;平均年龄(68.7±7.1)岁;切开组34例,其中男16例,女18例,平均年龄(67.7±6.9)岁。比较3组患者的手术时间、术中出血量、术后引流量、透视次数、住院时间、Cobb′s角、伤椎椎体前缘高度、视觉模拟评分(VAS)、Oswestry功能障碍指数(ODI)及相关并发症。结果3组术后伤椎前缘高度和Cobb′s角较术前均有明显改善(P<0.05),术后3组组间比较差异无统计学意义(P>0.05)。3组患者围手术期各项观察指标对比,经皮组的手术时间和透视次数比其他两组明显较多,差异有统计学意义(P<0.05);切开组术中出血量、住院时间与其他两组比较差异有统计学意义(P<0.05);3组间的术后引流量相互比较差异均有统计学意义(P<0.05)。3组患者术后VAS评分及ODI值较术前均降低(P<0.05),且经皮组及Wiltse组患者术后的VAS评分和ODI值均优于切开组患者(P<0.05)。切开组术后出现手术及基础疾病相关并发症较多,与其他两组比较差异有统计学意义(P<0.05)。结论治疗老年胸腰椎骨折,3种方法均可取得较好的临床效果,但经皮及Wiltse间隙微创入路相较于传统切开在软组织保护和术后功能康复方面更具优势,临床应用还需根据患者具体情况,采用合适的治疗方式才能够取得更好的疗效。

内源性H_(2)S、TAT、sPECAM-1对老年髋部骨折围术期下肢深静脉血栓形成的预测价值研究

目的探讨内源性硫化氢(endogenous hydrogen sulfidem,H_(2)S)、血浆凝血酶-抗凝血酶复合物(thrombin/antithrombin complex,TAT)及可溶性血小板内皮细胞黏附分子-1(soluble platelet endothelial cell adhesion molecule 1,sPECAM-1)对老年髋部骨折围术期下肢深静脉血栓形成(deep vein thrombosis,DVT)的预测价值。方法选取2018年11月至2019年7月北京积水潭医院急诊科住院接受手术治疗的新发老年髋部骨折患者187例,随机抽取120例患者(建模集),采用多因素logistic回归方程分析建模集患者DVT的影响因素,并建立预测模型;将剩余67例患者纳入验证集,进行预测模型的内部验证。结果建模集120例患者中男39例(32.50%),女81例(67.50%);平均年龄(78.6±7.1)岁;BMI为(22.5±4.2)kg/m^(2)。多因素logisitic回归分析显示,BMI、发病至就诊的时间及TAT越高,H_(2)S及sPECAM-1越低的患者,越容易发生DVT(P<0.05)。建立的DVT风险预测模型为:logit(P)=0.130×BMI+0.010×发病至就诊的时间-0.098×H_(2)S+0.039×TAT-0.322×sPECAM-1-3.581。预测模型的ROC曲线的AUC为0.844(95%CI:0.774~0.915,P=0.000)。应用验证集数据对模型进行内部验证结果显示验证模型的ROC曲线的AUC为0.816(95%CI:0.713~0.919,P=0.000)。结论基于BMI、受伤至入院时间、TAT、H_(2)S和sPECAM-1等因素建立的模型对于预测老年髋部骨折患者围术期DVT的发生具有良好的筛查能力。

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.

Buttress钢板结合空心加压螺钉治疗Hoffa骨折的疗效分析

目的:探讨Buttress钢板结合空心加压螺钉治疗Hoffa骨折的疗效。方法:收治Hoffa骨折患者13例,采用Buttress钢板结合空心加压螺钉治疗,观察治疗效果。结果:所有骨折均在术后4个月内愈合。优良11例,中等1例,差1例。结论:Buttress钢板结合空心加压螺钉治疗Hoffa骨折的疗效满意。

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.

Automatic fracture–vug identification and extraction from electric imaging logging data based on path morphology

We present a path morphology method to separate total rock pore space into matrix, fractures and vugs and derive their pore structure spectrum. Thus, we can achieve fine pore evaluation in fracture–vug reservoirs based on electric imaging logging data. We automatically identify and extract fracture–vug information from the electric imaging images by adopting a path morphological operator that remains flexible enough to fit rectilinear and slightly curved structures because they are independent of the structuring element shape. The Otsu method was used to extract fracture–vug information from the background noise caused by the matrix. To accommodate the differences in scale and form of the different target regions,including fracture and vug path, operators with different lengths were selected for their recognition and extraction at the corresponding scale. Polynomial and elliptic functions are used to fit the extracted fractures and vugs, respectively, and the fracture–vug parameters are deduced from the fitted edge. Finally, test examples of numerical simulation data and several measured well data have been provided for the verification of the effectiveness and adaptability of the path morphology method in the application of electric imaging logging data processing. This also provides algorithm support for the fine evaluation of fracture–vug reservoirs.

New scoring system in assessment of Hoffa's fat pad synovitis: A comparative study with established scoring systems

AIM To investigate the reliability of the established and new scoring methods for Hoffa's fat pad synovitis using magnetic resonance imaging(MRI).METHODS A total of 139 knees of 115 patients who underwent MRI of the knee with and without gadolinium contrast were enrolled in this study. Proton density(PD)-weighted, PD-weighted fat-suppressed(PD-FS), and postcontrast T1-weighted fat-suppressed(T1CE) images were used for evaluation. Using contrast and noncontrast images, our grading method for synovitis was performed to measure synovial thickness and signal intensity changes of the fat pad [Synovial membrane(SM) score], which was compared with the established methods,including MRI Osteoarthritis Knee Score(MOAKS), parapatellar synovitis score,Whole-Organ Magnetic Resonance Imaging Score(WORMS), and suprapatellar effusion diameter. Intraclass correlation coefficients(ICC) for intra and interobserver reproducibility and Spearman correlation coefficients(r) were calculated for the parapatellar synovitis score and each scoring method.RESULTS All of the scores presented substantial to almost perfect intrareliability. Among three readers, effusion diameter had substantial to almost perfect interreliability(ICC = 0.68-0.81) and WORMS had substantial interreliability(ICC = 0.61-0.70).For two out of three readers, there was substantial interreliability for the thickness score in T1CE(ICC = 0.55-0.69), SM scores in T1CE(ICC = 0.56-0.78)and PD-FS(ICC = 0.51-0.79), and parapatellar synovitis score in T1CE(ICC =0.53-0.72). The parapatellar synovitis score was significantly correlated with the thickness score in T1CE(r = 0.70) and the SM score in T1CE(r = 0.81) and PD-FS(r = 0.65).CONCLUSION The newly proposed quantitative thickness score on T1CE and the semiquantitative SM score on T1CE and PD-FS can be useful for Hoffa's fat pad synovitis.

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.