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Background@#This study aimed to clarify the characteristics of stress distribution caused by the placement of tapered wedge stems in bowed femurs compared with that in normal femurs and the effect of varus stem placement. @*Methods@#Models with normal and enhanced bowing were created from the right-side computed tomography data of a 17-yearold woman with the least bowing among 40 participants who underwent anterior cruciate ligament reconstruction or operative treatment for trauma in our hospital between January 2017 and May 2018. Finite element analysis was performed, assuming the tapered wedge stem was placed in the neutral and varus positions. @*Results@#Varus stem placement on a femur with normal bowing showed a deviation and increase of von Mises stresses in the medial femur. Stem placement on a bowed femur, even when placed in the neutral position, increased stress across the periprosthetic bone. When the stem was placed in the varus position, von Mises stress across the periprosthetic bone increased. Zone 7, with strong bowing, demonstrated 3.6-fold increased stress compared with normal femurs. The maximum tensile principal stress was greatest in zone 6 and increased in zones 3 and 4. @*Conclusions@#Surgeons should assess femoral bowing preoperatively and pay particular attention to intraoperative stem alignment for femurs with high bowing.
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Background@#Patients with developmental dysplasia of the hip (DDH) are known to have abnormal pelvic morphologies; however, rotation of innominate bone features remains unclear. Thus, we investigated innominate bone rotation in patients with DDH by measuring the associated angles and distances using three-dimensional (3D) computed tomography. @*Methods@#We defined four straight lines in pelvic 3D models: from the anterior superior iliac spine to the posterior superior iliac spine, from the anterior inferior iliac spine to the posterior inferior iliac spine, from the pubic tubercle to the ischial spine, and from the pubic tubercle to the ischial tuberosity. Similarly, we measured the angles formed by these lines using the vertical axis of the anterior pelvic plane on the horizontal plane and the horizontal axis on the sagittal plane. Additionally, we measured the distances between the femoral head centers and the acetabular centers in the coronal plane. @*Results@#The difference in internal rotation angle between the superior and inferior parts of the iliac bone was significantly lower, by approximately 1.7°, in the DDH group than in the control group (p = 0.007); the difference between the inferior and superior parts of the ischiopubic bone was significantly higher, by approximately 1.5°, in the DDH group (p< 0.001). In the sagittal plane, the sum of the superior aspect of the iliac bone and the inferior aspect of the ischium was significantly lower in the DDH group (p = 0.001) than in the control group. The distances between the femoral heads and the acetabula were significantly greater in the DDH group than in the control group (p = 0.03, p < 0.01, respectively). @*Conclusions@#Patients with DDH had a more internally rotated ilium and ischiopubic bone than normal individuals; however, it should be emphasized that internal rotation was reduced near the acetabulum, and the acetabulum was shifted laterally. Similarly, it was shown that patients with DDH had different rotations of the ilium and ischiopubic bone in the sagittal plane.
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Background@#There is a paucity of studies on the iliac curvature in developmental dysplasia of the hip (DDH). Here, we examined the iliac curvature in DDH using three-dimensional computed tomography. @*Methods@#We allocated cases with a center-edge angle of 25° to the control group (57 cases) and measured the straight line (line A) between the anterior and posterior superior iliac spines. We examined which part of the iliac bone line A passes through and classified the results into 4 categories (type A, inside the iliac bone; type B, through the iliac bone; type C, outside the iliac bone; and type D, both inside and outside the iliac bone) to evaluate the iliac wing curvature. After measuring the area and internal surface of the iliac wing using line A, we examined the correlation between these values, the interspinous distance, the superior iliac angle, and the center-edge angle. @*Results@#Distributions of the four types were compared between the two groups; there was no significant difference. The length of the portion of line A inside the ilium and the area formed by line A and the iliac wing, which shows the degree of iliac wing curvature, were not significantly different between the groups. There were no correlations between these values and the center-edge angle; however, there were weak positive correlations among the interspinous distance, the superior iliac angle, and the centeredge angle. @*Conclusions@#The inward nature of the iliac bone in patients with DDH is mainly due to the internal rotation of the entire iliac bone and less likely due to the curvature of the iliac bone.
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Background@#Plain computed tomography (CT) and magnetic resonance imaging (MRI) are useful for diagnosing adverse local tissue reactions after metal-on-metal total hip arthroplasty (THA), but metal artifacts can hamper radiological assessments near the implants. We sought to clarify the usefulness of 18F-fluorodeoxyglucose positron-emission tomography (18F-FDG-PET) CT and MRI in the periprosthetic region, which is difficult to assess after THA due to metal artifacts. @*Methods@#We performed preoperative 18F-FDG-PET/CT and 18F-FDG-PET/MRI, as well as plain CT and MRI, in 11 metal-on-metal THA patients who underwent revision surgery. @*Results@#Most patients showed high FDG uptake in the metal artifact areas and pseudotumors in the 18-F-FDG-PET/CT and 18-FFDG-PET/MRI scans. Intraoperative intra-articular macroscopic and histopathological intra-articular granulation tissue findings were suggestive of adverse local tissue reaction. @*Conclusions@#The enhanced uptake in the metal artifact areas seemed to reflect adverse local tissue reaction. Therefore, 18F-FDGPET/CT and 18-F-FDG-PET/MRI can be useful for the auxiliary diagnosis of adverse local tissue reactions after metal-on-metal THA.
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Background@#In total hip arthroplasty, the cup setting angle may affect the postoperative results. In recent years, both computed tomography-based navigation and computed tomography-free (imageless) navigation have been reported to produce high accuracy in cup installation; however, no direct comparison between these two methods has been performed. The present study aimed to directly compare the cup installation angle accuracy between computed tomography-based navigation and computed tomographyfree navigation in patients with Crowe’s classification stage I or II dysplastic osteoarthritis and to examine the factors affecting the cup installation accuracy. @*Methods@#Using both navigation systems for the same technique, primary total hip arthroplasty was performed by the same surgeon in 36 patients. A cup was installed using computed tomography-based navigation, and the installed cup was measured again using computed tomography-free navigation. We compared the error between the target angle and the intraoperative installation angle for each navigation method by performing statistical analyses. @*Results@#For computed tomography-based navigation, errors in the inclination and the anteversion angles compared to the target angle were 3.14° ± 1.55° and 1.47° ± 0.99°, respectively. For computed tomography-free navigation, the inclination and anteversion angle errors were significantly larger, i.e., 6.84° ± 4.78° and 5.43° ± 5.22°, respectively (p < 0.01). The inclination and anteversion angles of computed tomography-free navigation were correlated, and there were no significant factors influencing the error. @*Conclusions@#Computed tomography-based navigation is more accurate for cup installation than computed tomography-free navigation. When using computed tomography-free navigation, it is necessary to add technical schemes before and during surgery to improve the cup installation accuracy.
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Background@#Plain computed tomography (CT) and magnetic resonance imaging (MRI) are useful for diagnosing adverse local tissue reactions after metal-on-metal total hip arthroplasty (THA), but metal artifacts can hamper radiological assessments near the implants. We sought to clarify the usefulness of 18F-fluorodeoxyglucose positron-emission tomography (18F-FDG-PET) CT and MRI in the periprosthetic region, which is difficult to assess after THA due to metal artifacts. @*Methods@#We performed preoperative 18F-FDG-PET/CT and 18F-FDG-PET/MRI, as well as plain CT and MRI, in 11 metal-on-metal THA patients who underwent revision surgery. @*Results@#Most patients showed high FDG uptake in the metal artifact areas and pseudotumors in the 18-F-FDG-PET/CT and 18-FFDG-PET/MRI scans. Intraoperative intra-articular macroscopic and histopathological intra-articular granulation tissue findings were suggestive of adverse local tissue reaction. @*Conclusions@#The enhanced uptake in the metal artifact areas seemed to reflect adverse local tissue reaction. Therefore, 18F-FDGPET/CT and 18-F-FDG-PET/MRI can be useful for the auxiliary diagnosis of adverse local tissue reactions after metal-on-metal THA.
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Background@#In total hip arthroplasty, the cup setting angle may affect the postoperative results. In recent years, both computed tomography-based navigation and computed tomography-free (imageless) navigation have been reported to produce high accuracy in cup installation; however, no direct comparison between these two methods has been performed. The present study aimed to directly compare the cup installation angle accuracy between computed tomography-based navigation and computed tomographyfree navigation in patients with Crowe’s classification stage I or II dysplastic osteoarthritis and to examine the factors affecting the cup installation accuracy. @*Methods@#Using both navigation systems for the same technique, primary total hip arthroplasty was performed by the same surgeon in 36 patients. A cup was installed using computed tomography-based navigation, and the installed cup was measured again using computed tomography-free navigation. We compared the error between the target angle and the intraoperative installation angle for each navigation method by performing statistical analyses. @*Results@#For computed tomography-based navigation, errors in the inclination and the anteversion angles compared to the target angle were 3.14° ± 1.55° and 1.47° ± 0.99°, respectively. For computed tomography-free navigation, the inclination and anteversion angle errors were significantly larger, i.e., 6.84° ± 4.78° and 5.43° ± 5.22°, respectively (p < 0.01). The inclination and anteversion angles of computed tomography-free navigation were correlated, and there were no significant factors influencing the error. @*Conclusions@#Computed tomography-based navigation is more accurate for cup installation than computed tomography-free navigation. When using computed tomography-free navigation, it is necessary to add technical schemes before and during surgery to improve the cup installation accuracy.
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Background@#No study has compared flat and elevated-rim polyethylene liners in terms of stress distribution on the bearing surface. The purpose of this study was to investigate the difference in stress distribution between flat and elevated-rim polyethylene liners. @*Methods@#A stress analysis was performed by using the 3-dimensional finite element method. The cup was placed at an open angle of 20°, the flat liner and the liner with a 10° elevation was placed at inclination angles of 80°, 70°, and 60°. @*Results@#Compared with the 60° flat liner, the 80° and 70° flat liners showed higher stress at the liner edge. In the elevated-rim liner, the stress was high at the liner edge along the cup edge. When the von Mises equivalent stress was applied to each element of the liner, the high stress area (volume) was the largest for the 80° flat liner, second largest for the 80° elevated-rim liner, and third largest for the 70° flat liner. The average contact pressure also followed the same order. @*Conclusions@#Elevated-rim liners affect the stress distribution by increasing the area of contact. However, since elevated-rim liners exhibit high stress at the cup edge, they are likely to result in new problems including liner failure. These findings could aid surgeons in the selection of liners and determination of revision methods such as isolated liner exchange vs. acetabular cup revision for a well-fixed metal cup with a higher inclination angle in revision total hip arthroplasty.
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Disorders involving artificial joints are difficult to evaluate due to metal artifacts hindering plain computed tomography (CT) or magnetic resonance imaging (MRI). In the current case study 18F-fluoro-deoxyglucose positron emission tomography (18F-FDG-PET)/CT and MRI were used to confirm iliopsoas tendonitis within the metal artifact area following total hip arthroplasty (THA). The patient was a 61-year-old woman who developed hip pain on flexion of the ipsilateral hip after THA. Imaging studies were performed to evaluate for iliopsoas tendonitis due to impingement with the cup. Assessment of the iliopsoas muscle near the artificial joint was difficult due to the metal artifact on plain CT and MRI. Imaging using 18F-FDG-PET/CT and 18F-FDGPET/MRI showed uptake along the iliopsoas muscle. Therefore, revision was performed to resolve iliopsoas tendon impingement, and the preoperative pain resolved. The result of the current case study suggest 18F-FDGPET/CT or 18F-FDG-PET/MRI will be useful to detect iliopsoas tendonitis within metal artifact areas after THA.
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Disorders involving artificial joints are difficult to evaluate due to metal artifacts hindering plain computed tomography (CT) or magnetic resonance imaging (MRI). In the current case study 18F-fluoro-deoxyglucose positron emission tomography (18F-FDG-PET)/CT and MRI were used to confirm iliopsoas tendonitis within the metal artifact area following total hip arthroplasty (THA). The patient was a 61-year-old woman who developed hip pain on flexion of the ipsilateral hip after THA. Imaging studies were performed to evaluate for iliopsoas tendonitis due to impingement with the cup. Assessment of the iliopsoas muscle near the artificial joint was difficult due to the metal artifact on plain CT and MRI. Imaging using 18F-FDG-PET/CT and 18F-FDGPET/MRI showed uptake along the iliopsoas muscle. Therefore, revision was performed to resolve iliopsoas tendon impingement, and the preoperative pain resolved. The result of the current case study suggest 18F-FDGPET/CT or 18F-FDG-PET/MRI will be useful to detect iliopsoas tendonitis within metal artifact areas after THA.
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STUDY DESIGN: Cross-sectional study. PURPOSE: To investigate the relationship between ligamentum flavum (LF) thickening and lumbar segmental instability and disc degeneration and facet joint osteoarthritis. OVERVIEW OF LITERATURE: Posterior spinal structures, including LF thickness, play a major role in lumbar spinal canal stenosis pathogenesis. The cause of LF thickening is multifactorial and includes activity level, age, and mechanical stress. LF thickening pathogenesis is unknown. METHODS: We examined 419 patients who underwent computed tomography (CT) myelography and magnetic resonance imaging after complaints of clinical symptoms. To investigate LF hypertrophy, 57 patients whose lumbar vertebra had normal disc heights at L4–5 were selected to exclude LF buckling as a hypertrophy component. LF thickness, disc space widening angulation in flexion, segmental angulation, presence of a vacuum phenomenon, and lumbar lordosis at T12–S1 were investigated. Disc and facet degeneration were also evaluated. Facet joint orientation was measured via an axial CT scan. RESULTS: The mean LF thickness in all patients was 4.4±1.0 mm at L4–5. There was a significant correlation between LF thickness and disc degeneration; LF thickness significantly increased with severe disc degeneration and facet joint osteoarthritis. There was a tendency toward increased LF thickness in more sagittalized facet joints than in coronalized facet joints. Logistic regression analysis showed that LF thickening was influenced by segmental angulation and facet joint osteoarthritis. Patient age was associated with LF thickening. CONCLUSIONS: LF hypertrophy development was associated with segmental instability and severe disc degeneration, severe facet joint osteoarthritis, and a sagittalized facet joint orientation.
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Animais , Humanos , Constrição Patológica , Estudos Transversais , Hipertrofia , Degeneração do Disco Intervertebral , Ligamento Amarelo , Modelos Logísticos , Lordose , Imageamento por Ressonância Magnética , Mielografia , Osteoartrite , Canal Medular , Estenose Espinal , Coluna Vertebral , Estresse Mecânico , Tomografia Computadorizada por Raios X , Vácuo , Articulação ZigapofisáriaRESUMO
STUDY DESIGN: Retrospective cross-sectional study. PURPOSE: To investigate the relationship between ligamentum flavum (LF) hypertrophy and lumbar segmental motion. OVERVIEW OF LITERATURE: The pathogenesis of LF thickening is unclear and whether the thickening results from tissue hypertrophy or buckling remains controversial. METHODS: 296 consecutive patients underwent assessment of the lumbar spine by radiographic and magnetic resonance imaging (MRI). Of these patients, 39 with normal L4-L5 disc height were selected to exclude LF buckling as one component of LF hypertrophy. The study group included 27 men and 12 women, with an average age of 61.2 years (range, 23-81 years). Disc degeneration and LF thickness were quantified on MRI. Lumbar segmental spine instability and presence of a vacuum phenomenon were identified on radiographic images. RESULTS: The distribution of disc degeneration and LF thickness included grade II degeneration in 4 patients, with a mean LF thickness of 2.43±0.20 mm; grade III in 10 patients, 3.01±0.41 mm; and grade IV in 25 patients, 4.16±1.12 mm. LF thickness significantly increased with grade of disc degeneration and was significantly correlated with age (r=0.55, p<0.01). Logistic regression analysis identified predictive effects of segmental angulation (odds ratio [OR]=1.55, p=0.014) and age (OR=1.16, p=0.008). CONCLUSIONS: Age-related increases in disc degeneration, combined with continuous lumbar segmental flexion-extension motion, leads to the development of LF hypertrophy.
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Feminino , Humanos , Masculino , Envelhecimento , Estudos Transversais , Hipertrofia , Degeneração do Disco Intervertebral , Ligamento Amarelo , Modelos Logísticos , Imageamento por Ressonância Magnética , Estudos Retrospectivos , Coluna Vertebral , VácuoRESUMO
STUDY DESIGN: Retrospective cross-sectional study. PURPOSE: This study analyzed the prevalence and distribution of horacic and lumbar compressive lesions in cervical spondylotic myelopathy as well as their relationships with cervical developmental spinal canal stenosis (DCS) by using whole-spine postmyelographic computed tomography. OVERVIEW OF LITERATURE: There are few studies on missed compressive lesions of the spinal cord or cauda equina at the thoracolumbar level in cervical spondylotic myelopathy. Furthermore, the relationships between DCS, and the prevalence and distribution of thoracic and lumbar compressive lesions are unknown. METHODS: Eighty patients with symptomatic cervical spondylotic myelopathy were evaluated. Preoperative image data were obtained. Patients were classified as DCS or non-DCS (n=40 each) if their spinal canal longitudinal diameter was or =12 mm at all levels, respectively. Compressive lesions in the anterior and anteroposterior parts, ligamentum flavum ossification, posterior longitudinal ligament ossification, and spinal cord tumors at the thoracolumbar levels were analyzed. RESULTS: Compressive lesions in the anterior and anteroposterior parts were observed in 13 (16.3%) and 45 (56.3%) patients, respectively. Ligamentum flavum and posterior longitudinal ligament ossification were observed in 19 (23.8%) and 3 (3.8%) patients, respectively. No spinal cord tumors were observed. Thoracic and lumbar compressive lesions of various causes tended to be more common in DCS patients than non-DCS patients, although the difference was statistically insignificant. CONCLUSIONS: Surveying compressive lesions and considering the thoracic and lumbar level in cervical spondylotic myelopathy in DCS patients are important for preventing unexpected neurological deterioration and predicting accurate neurological condition after cervical surgery.
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Humanos , Cauda Equina , Constrição Patológica , Estudos Transversais , Ligamento Amarelo , Ossificação do Ligamento Longitudinal Posterior , Prevalência , Estudos Retrospectivos , Canal Medular , Medula Espinal , Doenças da Medula Espinal , Neoplasias da Medula EspinalRESUMO
STUDY DESIGN: Retrospective study. PURPOSE: The aim of the present study is to analyze the prevalence and distribution of cervical and thoracic compressive lesions of the spinal cord in lumbar degenerative disease, using whole-spine postmyelographic computed tomography. OVERVIEW OF LITERATURE: Of the various complications resulting from spinal surgery, unexpected neurological deterioration is the most undesired. There are reports of missed compressive lesions of the spinal cord at the cervical or thoracic level in lumbar degenerative disease. METHODS: There were 145 consecutive patients with symptomatic lumbar degenerative disease evaluated. Before the lumbar surgery, image data were obtained. The following parameters at the cervical and thoracic levels were analyzed: compressive lesions from the anterior parts; compressive lesions from the anterior and posterior parts; ossification of the ligamentum flavum; ossification of the posterior longitudinal ligament; and spinal cord tumor. RESULTS: Compressive lesions from the anterior parts were observed in 34 cases (23.4%). Compressive lesions from the anterior and posterior parts were observed in 34 cases (23.4%). Lesions of ossification of the ligamentum flavum were observed in 45 cases (31.0%). Lesions of ossification of the posterior longitudinal ligament were observed in 15 cases (10.3%). Spinal cord tumor was not observed. CONCLUSIONS: A survey of compressive lesions at the cervical or thoracic level in lumbar degenerative disease is important in preventing unexpected neurological deterioration after the lumbar surgery.
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Humanos , Ligamento Amarelo , Ligamentos Longitudinais , Prevalência , Estudos Retrospectivos , Neoplasias da Medula Espinal , Medula EspinalRESUMO
STUDY DESIGN: A retrospective study. PURPOSE: The aim of present study was to investigate imaging findings suggestive of cauda equina entrapment in thoracolumbar and lumbar burst fractures. OVERVIEW OF LITERATURE: Burst fractures with cauda equina entrapment can cause neurologic deterioration during surgery. However, dural tears and cauda equina entrapment are very difficult to diagnose clinically or radiographically before surgery. METHODS: Twenty-three patients who underwent spinal surgery for thoracolumbar or lumbar burst fractures were enrolled in this study. In magnetic resonance imaging T2-weighted images of the transverse plane, we defined cauda equina notch sign (CENS) as a v-shaped image that entrapped cauda equina gathers between lamina fractures. We evaluated the fractured spine by using CENS and lamina fractures and the rate of available space for the spinal canal at the narrowest portion of the burst fracture level. We classified patients into entrapment group or non-entrapment group, based on whether cauda equina entrapment existed. RESULTS: Lamina fractures were detected in 18 (78.3%) and CENS were detected in 6 (26.1%) of 23 burst-fracture patients. Cauda equina entrapment existed in all the patients with CENS. In addition, the rate of available space for the spinal canal increased according to logistic regression. The size of the retropulsed fragment in the spinal canal was the most reliable of all the factors, suggesting cauda equina entrapment. CONCLUSIONS: CENS was the most predictable sign of cauda equina entrapment associated with burst fractures.
