| ObjectiveInternal fixation is the first choice for patients with femoral neck fracture under the age of 60 and those without displacement over the age of 60.The conventional method is closed reduction and hollow screw internal fixation.During and after the treatment of femoral neck fracture,we often use X-ray fluoroscopy to evaluate the degree of fracture reduction and the position of internal fixation screw,so as to determine the effectiveness and safety of screw fixation.However,in clinical practice,we found that even if the screw position was satisfactory in X-ray multi-angle fluoroscopy,some patients still had poor screw position or position variation penetrating the bone cortex after operation.Since the appearance of CT,CT has gradually become an important auxiliary examination in the diagnosis and treatment of diseases in orthopedic surgery.This topic reviewed and summarized the imaging data of patients with femoral neck fractures treated with cannulated screws.By analyzing the postoperative X-ray and CT images of patients with femoral neck fractures treated with cannulated screws,we compared the difference between CT evaluation screw position and double-angle X-ray fluoroscopy results,then guide the X-ray fluoroscopy scheme in clinical treatment.MethodSelect 60 patients with femoral neck fracture who underwent cannulated screw internal fixation from January 2021 to December 2022 in the Affiliated Central Hospital of Shenyang Medical College,including 36 males and 24 females.The average age of the patients was(52.23 ± 11.55)years old,all of which were unilateral femoral neck fractures.All patients had complete preoperative anteroposterior radiographs of both hips,postoperative anteroposterior lateral radiographs of the affected hip joint and axial radiographs of the femoral neck,postoperative plain CT scan of the hip and three-dimensional reconstruction imaging data.Two orthopedic doctors(Observer A as the chief physician and Observer B as the resident)observed and calculated the imaging data of patients.Among them,observers A and B jointly determined the number of the perforated cortical bone of the hollow screw and analyzed the location of the screw.The two observers independently measured the preoperative imaging data of the healthy side to measure the cervical trunk angle on X-ray and CT,the included angle between the longitudinal axis of the affected side of the femoral shaft and the long axis of the hollow screw(the cervical trunk angle of the hollow screw)and TAD.Measurement method of cervical trunk Angle on healthy side X-ray: select the midpoint of the femoral medullary cavity under the lesser trochanter and the midpoint of the farthest femoral medullary cavity,connect the two midpoints as the longitudinal axis of the femoral shaft,and take the midpoint of the largest bone cortex line of the femoral head as the midpoint,the shortest femoral neck as the midpoint,connect the two midpoints as the long axis of the femoral neck,and then use the angle measurement function of the PACS working system to measure the included angle formed by the two lines as the neck shaft angle on the X-ray.The measurement method of the neck shaft angle on the contralateral CT: select the middle section of the femoral neck on the coronal plane,the middle point of the femoral medullary cavity under the lesser trochanter and the middle point of the distal femoral medullary cavity,connect the two midpoints as the longitudinal axis of the femoral shaft,and take the midpoint of the largest part of the femoral head bone cortex line,the shortest part of the femoral neck,and connect the two midpoints as the long axis of the femoral neck,After that,the angle measurement function of PACS working system is used to measure the included angle formed by two straight lines,which is the neck-shaft angle on CT.The measurement method of hollow nail neck dry angle on X-ray: the longitudinal axis of the femoral shaft is the same as above,and the midpoint of both ends of the hollow nail is selected.The line between the midpoint is the hollow nail axis,and the included angle between the hollow nail axis and the longitudinal axis of the femoral shaft is the neck dry angle of the hollow nail on X-ray.Measurement method of hollow nail neck dry angle on CT: select the longest section image of CT plane hollow nail development,the longitudinal axis of the femoral shaft is the same as the front,connect the midpoint of both ends of the hollow nail as the hollow nail axis,and get the included angle of the two straight lines after connection as the hollow nail neck dry angle on CT.Measurement method of apex distance on X ray: take the midpoint of the tip of the hollow nail in the positive and lateral position of X ray,measure the distance from this point to the apex of the femoral head,and add the two to get the apex distance on X ray.Measurement method of the apex distance on CT: select the CT plane where the widest tip of the sagittal plane and coronal plane screw is located,and measure the distance between the middle point of the hollow screw tip and the apex of the femoral head on this plane,which is the apex distance.The difference between the data measured by X-ray and CT was compared and analyzed.To evaluate the accuracy of X-ray and CT measurements on several measures.SPSS26.0 software was used for statistical processing of the data,and P < 0.05 was considered statistically significant.Result1.The measurement results are as follows(1)Number of hollow screws penetrating bone cortexTwo orthopedic doctors jointly analyzed the X-ray images and CT images of 60 patients with femoral neck fracture after operation and confirmed the number,position and ratio of hollow screw penetration.X-ray observation results: 1 case of hollow screw penetrating through the bone cortex,and the number of hollow screw penetrating through the bone cortex accounted for 1.67% of the total number.The exit position is below the femoral neck.There is no hollow screw penetrating through the femoral head and the upper part of the femoral neck.CT observation results: cannulated screws penetrated 11 cases,and the number of cannulated screws penetrating the bone cortex accounted for 18.33% of the total number on X-ray.Among them,3 cases were penetrated from the femoral head,accounting for 27.27% of the total.7 cases penetrated from the posterior superior position part of the femoral neck,accounting for 63.64% of the total number.One case was penetrated from the lower part of the femoral neck,accounting for 9.09% of the total number.There is no screw penetrating the bone cortex at the front and upper part of the femoral neck.In the above results,X-ray and CT showed that 1 case of hollow screw penetrating the bone cortex;X ray showed no penetration but CT showed 10 cases of bone cortex penetration;X-ray and CT showed no screw penetrating the bone cortex in 49 cases.Chi-square test was used to analyze the difference of the number of hollow nails penetrating the bone cortex obtained by the two methods,and the P value was0.002<0.05,the difference was statistically significant.(2)Neck-shaft angle of healthy sideObserver A measured the cervical-trunk angle by X-ray image as(130.58 ± 3.74)°,and the cervical-trunk angle by CT method as(132.76 ± 3.57)°.The paired sample T test of the cervical trunk angle measured by X-ray and CT of observer A was used to analyze the difference,and the P value was 0.127>0.05 was obtained.There was no significant difference between the two measurement methods.Observer B measured the neck-shaft angle by X-ray image as(129.42 ± 3.46)°,and the neck-shaft angle by CT method was(131.00 ± 3.56)°.The paired sample T test of the cervical trunk angle measured by X-ray and CT of observer B was used to analyze the difference,and the P value was 0.092>0.05 was obtained.There was no significant difference between the two measurement methods.The paired sample T test was used to analyze the difference of the contralateral cervical trunk angle measured by X ray of the two observers,and the P value was0.122>0.05,and the difference was not statistically significant.The contralateral cervical trunk angle measured by CT of two observers was analyzed by paired sample T test,and the P value was 0.184>0.05,and the difference was not statistically significant.(3)Angle between the longitudinal axis of femoral shaft and the long axis of hollow nail on X-ray and CTThe angle of the hollow nail’s neck and trunk measured by observer A through X-ray was(136.64 ± 4.88)°,and the angle of the hollow nail’s neck and trunk measured by CT was(142.70 ± 6.62)°.The paired sample T test was performed on the neck and trunk angle of hollow nail measured by observer A using X ray and CT to analyze the difference,and the P value was 0.003<0.01,which was statistically significant.There was significant difference between the two measurement methods.Observer B measured the neck-shaft angle of the hollow nail by X ray as(133.54± 4.74)°,and by CT as(141.62 ± 5.86)°.The difference of the neck and shaft angle of hollow nail obtained by the two methods was analyzed by paired sample t-test,and the P value was 0.001<0.01,the difference was statistically significant,and there was significant difference between the two methods.The paired sample t-test was used to analyze the difference between the two observers in the neck and trunk angle of the hollow nail measured by X-ray,and the P value was 0.032<0.05,the difference was statistically significant.The difference between the two observers was analyzed by t-test on the neck and shaft angle of hollow screw measured by CT,and the P value was 0.175>0.05,and the difference was not statistically significant.Pearson correlation analysis was performed on the uninjured cervical stem angle measured by observers A and B and the cervical stem angle of hollow screw on X ray and CT,with correlation coefficients of 0.571 and 0.293 respectively,indicating that the uninjured cervical stem angle and the cervical stem angle of hollow screw on X ray were moderately correlated,while the uninjured cervical stem angle and the cervical stem angle of hollow screw on CT were weakly correlated.(4)CT measurement of the anteversion angle of the screw through the femoral neckThe measured angles are 38.28 °,31.37 °,27.58 °,31.21 °,30.23 °,30.61 ° and37.02 ° respectively.The angle calculated by SPSS 26.0 is(32.33 ± 3.86)°.During the operation,35 ° or 145 ° fluoroscopy can be used to observe whether the cannulated screw penetrates the bone cortex at the posterior upper part of the femoral neck.(5)TAD value measured on X-ray and CTThe TAD value of observer A measured by X-ray was(24.84 ± 10.32)mm,the TAD value measured by CT method was(22.76 ± 8.43)mm,and the P value was0.019<0.05,the difference was statistically significant,and there was significant difference between the two measurement methods.The TAD value of observer B measured by X-ray is(27.21 ± 9.52)mm,and the TAD value measured by CT method is(22.55 ± 7.76)mm.The paired sample T test of the TAD value measured by observer B and CT is used to analyze the difference,and the P value is 0.002<0.01,the difference is statistically significant,and there is significant difference between the two measurement methods.The paired sample t-test was used to analyze the difference of TAD measured by X ray of two observers,and the P value was 0.007<0.01,the difference was statistically significant.The difference of TAD measured by CT of two observers was analyzed by t-test,P=0.231>0.05,and the difference was not statistically significant.ConclusionEven if the position of the double-angle X-ray fluoroscopy screw is satisfactory during the operation,the rate of the hollow screw passing through the posterior superior position part of the femoral neck after the internal fixation of the femoral neck fracture is still high,followed by the femoral head and the lower part of the femoral neck.It is recommended to increase the projection angle of the C-arm at 35 ° or 145 °during intraoperative multi angle fluoroscopy to observe whether the hollow screw has penetrated.The reconstruction CT has a better evaluation effect than the X-ray observation of the hollow screw neck stem angle,and the CT method is better than the X-ray measurement of the apex distance,It is recommended to take additional CT after operation to re-examine the patient,which can better evaluate the degree of fracture reduction and the position of internal fixation screw,and then determine the effectiveness and safety of screw fixation. |
