Sagittal Research Articles

Prediction of Postoperative Mechanical Complications in ASD Patients Based on Total Sequence and Proportional Score of Spinal Sagittal Plane

This article aimed to predict the occurrence of postoperative mechanical complications in adult spinal deformity (ASD) patients through the total sequence and proportional score of the spinal sagittal plane, to improve the quality of life of patients after surgery. The study adopted a comprehensive evaluation and data analysis method, including data collection and preprocessing, feature selection, model construction and training, and constructed a prediction model based on the Random Forest (RF) algorithm. The experimental results showed that the model significantly reduced the risk of complications in randomized controlled trials. The incidence of mechanical complications in the experimental group was 10%, while that in the control group was 25%, with statistical significance (P<0.05). In addition, in retrospective data analysis, the accuracy of the article's model on five datasets ranged from 89% to 93%, outperforming logistic regression and support vector machine models, and performing well on other performance data. In prospective studies, the model's predictions showed good consistency with the actual occurrence of complications. Sensitivity analysis shows that the model has low sensitivity to changes in key parameters and exhibits stability, indicating that the model proposed in this article is suitable for uncertain medical environments. The expert rating further confirmed the effectiveness and practicality of the model in predicting postoperative mechanical complications in ASD patients, with the highest score reaching 4.9. These data demonstrate the high accuracy and clinical potential of the model in predicting postoperative complications of ASD.

Associations Between Body Mass Index, Gait Biomechanics, and In Vivo Cartilage Function After Exercise in Those With Anterior Cruciate Ligament Reconstruction

Background: Both high body mass index (BMI) and anterior cruciate ligament reconstruction (ACLR) independently influence knee osteoarthritis risk. Preliminary evidence shows the combination of these risk factors leads to poorer recovery and altered biomechanical outcomes after ACLR, but few studies have directly evaluated early changes in cartilage health between normal-BMI and high-BMI groups in this population. Purpose: To evaluate ultrasound-based measures of cartilage strain and compositional changes (via echo-intensity [EI]) in response to an incline walking stress test between normal-BMI and high-BMI individuals with ACLR. A secondary evaluation was conducted of associations between habitual walking biomechanics (ie, ground-reaction forces, sagittal knee kinetics and kinematics) and cartilage strain and EI outcomes. Study Design: Controlled laboratory study. Methods: Gait biomechanics and femoral trochlear ultrasound analyses were evaluated in 64 participants with ACLR who had normal BMI (BMI < 27.0; n = 40) and high BMI (BMI ≥ 27.0; n = 24). Ultrasound images were collected bilaterally before and after an incline treadmill walk, and medial and lateral trochlear strain and EI changes pre-post exercise were used to compare BMI groups and limbs. Gait outcomes included ground-reaction forces, peak sagittal plane knee moments, angles, and excursions and were used to determine associations with cartilage outcomes in the entire cohort. Results: High-BMI individuals with ACLR exhibited greater medial trochlear cartilage strain in the ACLR limb compared with normal-BMI individuals (approximately 6%; P < .01). In those with high BMI, the ACLR limb exhibited greater medial trochlear strain relative to non-ACLR limbs (approximately 4%; P < .05), but between-limb differences were not observed in the normal-BMI group (P > .05). Medial trochlear EI changes were greater bilaterally in those with high BMI compared with normal-BMI ACLR counterparts (approximately 10%; P < .01). Last, individuals who walked with greater peak knee flexion angles exhibited less medial cartilage strain (ΔR2 = 0.06; P = .025). Conclusion: The data suggested that high BMI affects cartilage functional properties after ACLR, whereas smaller knee flexion angles were associated with larger medial cartilage strain. Clinical Relevance: High-BMI individuals with ACLR may represent a subset of patients exhibiting earlier declines in cartilage functional integrity in response to loading, necessitating additional or more targeted interventions to mitigate disease development.

Mediolateral Margin of Stability highlights motor strategies for maintaining dynamic balance in older adults.

The dynamical nature of gait increases fall risk for older adults as the Center of Mass (COM) is constantly displaced inside and outside the Base of Support (BOS). Foot placement and leg joint moments are the primary mechanisms controlling dynamic balance. The Margin of Stability (MOS) quantifies the distance between the COM dynamical state and the BOS. While research examined how aging affects the relationship between foot placement and MOS, the relationship to leg moments is unexamined. Examining this relationship would elucidate whether aging increases fall risk from changes in the joint moments controlling the COM. Fourteen older (66.9 ± 4.3 years) and sixteen young (26.3 ± 3.6 years) adults walked along a 12m path for three trials. The MOS, hip and ankle moments in sagittal and frontal planes were analyzed. For the knee, only the sagittal plane was analyzed. MOS was calculated as the distance between the extrapolated-COM and the Center of Pressure per step. Statistical Parametric Mapping independent t-tests assessed group differences. Cross-correlation quantified MOS and joint moment relationships per plane during single-stance. No group differences in walking speed were observed. A larger frontal plane MOS, hip abduction and ankle eversion moment occurred for older adults. Cross-correlation demonstrated moderate and strong relationships for the hip-MOS for both groups in the sagittal plane. Older adults had a larger sagittal plane hip-MOS correlation than young adults. The larger mediolateral MOS in older adults may indicate attempts to avoid lateral balance loss by shifting their COM away from their BOS lateral boundaries during single-stance. However, this strategy moves the COM toward the BOS medial borders potentially pre-maturely terminating the contralateral swing phase during medial destabilization. The stronger sagittal plane hip-MOS relationship in older adults may reflect increased coupling between hip moments and the COM to control dynamic balance.

Kinematic analysis of the back squat at different load intensities in powerlifters and weightlifters

IntroductionThis study aimed to evaluate the angular kinematics of the hip, knee, ankle, and the linear kinematics of the barbell during the back squat (BS) at different load intensities in powerlifters and weightlifters.MethodsSeventeen athletes were recruited (n = 14 powerlifters; n = 3 weightlifters). The 1-RM of the BS of each participant was calculated and, 1-week after, each participant was asked to perform 5 trials of the BS at different load intensities (i.e., 60%, 70%, 80%, 90%, 100%) of the 1-RM. An action camera recorded the execution of each BS trial in the sagittal plane and, afterward, the videos were analyzed by measuring the range of motion (ROM) of hip, knee, and ankle for the angular kinematics, and the timing, distances, speeds, and accelerations of the barbell for the linear kinematics.ResultsRegarding the angular kinematics, no significant differences were found in the parameters in the starting and ending positions among the 5 trials, while a significant decrease was found in the hip relative angle (p = 0.026) in the maximum flexion position as load intensity increased. Regarding the linear kinematics, a significant difference was found in the descent acceleration (p = 0.049) in the descent phase, while a significant difference was found in the ascent speed (p &amp;lt; .001) and vertical speed of ascent (p &amp;lt; .001) in the ascent phase, which decreased as load intensity increased.DiscussionOur findings show that the angular and linear kinematics of BS change as load intensity increases.

Effects of different hinge positions on tibial rotation in uniplanar medial opening wedge high tibial osteotomy with three-dimensional tibial models.

To investigate the effects of different hinge positions in the sagittal and axial planes on distal tibial rotation (DTR) during medial opening wedge high tibial osteotomy (MOWHTO) with three-dimensional tibial models. Preoperative CT data from 30 knee joints in 30 patients who underwent surgery for varus malalignment of knee were included. 1 standard hinge position (0°), 6 axial planes (±5°, ±10°, ±15°), and 6 sagittal planes (±5°, ±10°, ±15°) hinge positions were defined and virtual uniplanar osteotomy was performed. The correction angle of each model was generated using Fujisawa's point. Participants' baseline characteristics, radiologic parameters and DTR were measured. One-Way Repeated Measures ANOVA and single factor linear regression analysis were used to analyze the association between tibial rotation and hinge position in the sagittal and axial planes. We found a clear linear correlation between changes in hinge position in the sagittal plane and DTR. The changes in DTR were the smallest when the hinge position was at 5°, where internal or external rotation of the DTR may occur. When the front aspect of hinge axis rotated distally, DTR tended towards internal. Meanwhile, when the front aspect of hinge axis rotated proximally, DTR tended towards external. There were no correlations with every hinge axis position in the axial plane. It is sagittal but not axial hinge axis affects DTR in uniplanar MOWHTO with three-dimensional tibial models. In the sagittal plane, every change in hinge position was significantly linearly correlated with DTR. However, no linear correlations were observed between every hinge position change in the axial plane.

Intramedullary nailing of tibial shaft fractures in the semi-extended position using suprapatellar approach: A case series in Hong Kong

Introduction The objective of this case series is to evaluate the clinical outcome of patients with tibial shaft fractures treated by suprapatellar nailing at a 2-year follow-up and to review available literature concerning this approach. Method and material This is a retrospective single-centre case series to evaluate patients' post-operative status at 2-year intervals. Fifteen (15) patients underwent intramedullary nailing with a supra-patella approach during the year 2019–2020 and consented to participate in this case series. Patients were regularly followed up in the outpatient clinic and evaluated in terms of range of movement, walking status and radiologically with RUST score and tibia alignment. Their functional outcome was assessed by a questionnaire including OKS, VAS, and Kujula scores. Results At post-op 2 years intervals, all patients had radiologically healed fractures as evidenced by RUST score and tibia alignment within five degrees in the coronal and sagittal plane, the functional outcome of the suprapatellar approach was satisfactory in the visual analogue scale and various knee scores. All patients achieved a full range of movement and could walk unaided. Discussion Technical tricks and tips for the suprapatellar approach are discussed. Literature review showed satisfactory outcomes for intramedullary nailing for tibial shaft fracture in different parts of the world. Compared with the infra-patellar approach, the suprapatellar approach is superior in fracture alignment but has no significant difference in terms of pain, disability and range of movement. Potential risk of suprapatellar approach is discussed including possible cartilage damage and intra-articular sepsis. Conclusion There is a good clinical outcome of the suprapatellar approach to tibial nail radiologically and functionally. Results are in line with the literature review, which also showed that compared with the infra-patellar approach, the suprapatellar approach is associated with better alignment and less knee pain but no significant difference in range of movement and disability.

Sensitivity analysis of an inertial calibration method: Influence of leg position on 3D knee kinematics

BackgroundInertial systems are increasingly used to analyze human motion, especially for gait analyses and in clinical settings. Calibration methods for these systems are designed for ease of implementation, and previous studies have shown that they can provide accurate knee kinematics in the sagittal plane. However, the reason of their lack of accuracy in the other planes (i.e., transverse and frontal) remain unknown. Research questionThis study aimed to evaluate the sensitivity of one posture of a double-pose calibration method to analyse 3D knee kinematics during gait with two magnetic inertial measurement units (MIMU). This method consists of a standing posture and a posture with the leg stretched forward in the sagittal plane, which together define the sagittal plane. Our hypothesis was that a change in the definition of the sagittal plane during the calibration process was likely to affect the assessment of knee kinematics in the frontal and transverse planes. MethodsTen healthy participants wearing the KneeKG system and two MIMU completed the calibration process in five different leg positions (0°, 3°, 5°, 10° or 15° from the sagittal plane) for the second calibration posture. After static calibration, the participants walked on an instrumented treadmill at a speed of 1.1 m/s and 3D knee kinematics were calculated using the five different calibration conditions. ResultsMean absolute difference (MAD) between the swing-phase peak value of the curve corresponding to the leg in the sagittal plane (0° shift from this plane) when performing the second calibration posture and each of the other curves was 0.20–0.46° for knee flexion, 1.67–2.90° for adduction, and 0.72–1.46° for external rotation. MAD of the swing-phase peak value in the frontal plane was correlated (R2=0.81) with the angulation of the femur in the sagittal plane during calibration. SignificanceAn angular shift from the sagittal plane when performing a double-pose calibration method induces a minimal influence on the knee flexion/extension but larger influences on secondary knee motions.

Feasibility of a new bicycle ergometer with adjustable pedaling configuration for personalized lower limb rehabilitation

Muscle atrophy due to prolonged immobilization leads to severe dysfunction and progression of disease and injury. This highlights the necessity for early rehabilitation, even during the non-ambulatory stages. As manifestations vary among individuals, target-specific rehabilitation is crucial for achieving optimal outcomes. Conventional bicycle ergometers, despite their wide usage in rehabilitation and sports training, fail to adequately recruit the muscles that predominantly operate in the coronal or axial plane. This is thought to be due to the restriction of pedaling trajectory in the sagittal plane. This study introduces a new bicycle ergometer capable of tilting the pedaling plane and adjusting the pedal orientation, in order to alter muscle recruitment patterns and limb alignments. A biomechanical analysis of eight healthy volunteers suggests that our device can elicit dynamic valgus/varus alignment and alter the axial rotations of the lower extremities. An electromyography analysis revealed a significant increase in the activation of specific muscle groups, particularly the abductors and adductors, suggesting promising results for targeted muscle recruitment. We expect this ergometer to provide a new method for target-specific rehabilitation and the treatment of bedridden patients or those with weak muscles.

How does the position of the pelvis and femur influence the selection of prosthesis size during 2D preoperative planning for total hip arthroplasty?

PurposeTotal Hip Arthroplasty (THA) is the primary treatment for hip diseases today. Nevertheless, total hip arthroplasty has its challenges, and one of these challenges is the potential for incorrect execution of the preoperative planning process. Such errors can lead to complications such as loosening and instability of the prosthesis and leg length discrepancy. In this study, we used human phantoms to investigate the influence of pelvic and femoral factors on prosthesis size selection in the preoperative planning of total hip arthroplasty and to provide a reference standard for clinical imaging in preoperative planning of total hip arthroplasty.MethodsIn this experiment, we utilised a custom-made experimental device that enabled us to manipulate the movement of the pelvis and femur in various directions. The device also incorporated sensors to control the angle of movement. By obtaining X-rays from different positions and angles, we were able to determine the size of the prosthesis based on the 2D preoperative planning generated by the mediCAD software.ResultsWhen the pelvis was in a nonneutral position, the size of the acetabular cup varied within a range of three sizes. Similarly, when the femur was in a nonneutral position, the size of the femoral stem varied within a range of two sizes. The movement of the pelvis and femur in the coronal plane, relative to the neutral position, did not impact the selection of the prosthesis size. However, the motion of the pelvis and femur in the sagittal and transverse planes had a notable effect.ConclusionThe selection of the prosthesis size for preoperative planning can be significantly influenced by specific positions of the pelvis and femur. It is crucial for the radiographer to ensure that the pelvis and femur maintain a standard neutral position, particularly in the sagittal and transverse planes, during the image acquisition process.

Diagnostic considerations and orthodontic treatment approaches of adolescents with the dentoalveolar form of class II malocclusion

Relevance. Class II malocclusion (distal occlusion) is a common pathology of the maxillofacial region in the sagittal plane and is one of the most prevalent malocclusions. Studies confirm that Class II malocclusion in adolescents exhibits significant variability, prompting the development of various treatment approaches using both removable and fixed orthodontic appliances. The challenges of adolescence include concurrent physiological and psychological changes, which can complicate the treatment process.Purpose. To enhance the effectiveness of orthodontic treatment for patients with the dentoalveolar form of Class II malocclusion by utilizing the Rotation-Torque Index (RTI).Material and methods. A study was conducted on 49 residents of St. Petersburg with physiological occlusion types, who were included in the control group. The main group comprised 95 adolescents (aged 12-18) with the dentoalveolar form of Class II malocclusion classified into three levels of severity, based on the proposed working prognostic classification.Results. A new method was developed to calculate a coefficient that describes the relationship between the position of the upper and lower jaws and the torque of the central incisors. This coefficient helps predict treatment outcomes and guides the selection of the optimal treatment strategy. The Rotation-Torque Index (RTI) was introduced to quantify the relationship between the position of the jaws in the skull (SNA, SNB) and the inclination of the central incisors of the upper jaw relative to the nasal line (NL) and those of the lower jaw relative to the mandibular line (ML).Conclusions. Based on the Rotation-Torque Index (RTI), a working prognostic classification and treatment strategies for patients with the dentoalveolar form of Class II malocclusion were proposed.

Pelvic tilt and stiffness of the muscles stabilising the lumbo-pelvic-hip (LPH) complex in tensiomyography examination.

The objective of the study was to initially validate the hypothesis about the relationship between the pelvic tilt angle in the saggital plane and the functional state of muscles stabilising the lumbo-pelvic-hip (LPH) complex expressed as a change in their stiffness in a tensiomyography examination. Forty five women aged 19-30 years took part in an observational (cross-sectional) study. The examination involved measurements using the tensiomyography method (TMG). The stiffness of muscles stabilising the LPH complex expressed as a maximal muscle displacement (Dm variable) was assessed and the relationship between muscle stiffness and the value of the pelvic tilt (PT) in the sagittal plane was determined. The analysis showed significant differences in the values of medians of the muscle displacement (Dm) values in groups identified in terms of the value of pelvic tilt (Table 1) for Erector Spinae (ES) muscles (p = 0.0012), Gluteus Maximus (GM) muscles (p = 0.0004), Rectus Abdominis (RA) muscles (p = 0.0005), Obliquus abdominis externus (OAE) muscles (p = 0.0002*) and Rectus Femoris (RF) muscles (p = 0.0071). The results of the correlation analysis performed using the Spearman rho correlation coefficient between the value of pelvic tilt and muscle stiffness (Dm) show the following significant relations for ES muscles (p = 0<0.0001), GM muscles (p<0.0001), RA muscles (p<0.0001) and OAE muscles (p<0.0001). However, a clear direction of changes in stiffness in accordance with the description of relations defined as Lower Crossed Syndrome was not confirmed. A tensiomyographic examination did not show clear relations between the value of pelvic tilt and stiffness of muscles stabilising the lumbar-pelvic-hip complex. The mechanism of Lower Crossed Syndrome (LCS) may be not the only model explaining the relations between musculofascial structures of the hip-lumbar area. The implications of the LCS should not be the only basis for the therapy of disorders resulting from an incorrect position of the pelvis in the sagittal plane.

Upper extremity functions, spinal posture, and axial rigidity in patients with parkinson's disease.

Upper extremity dysfunction is frequently seen in Parkinson's disease (PD). Existing research has shown that bradykinesia, which is main symptom of PD, is primarily responsible but the combined effects of spinal posture and axial rigidity on upper extremity functions were not investigated yet. The aim of this study was to investigate upper extremity functions in patients with PD and to evaluate relationship of these with spinal posture and axial rigidity. This prospective controlled study included 40 patients with PD and 40 healthy controls. Upper extremity function was measured with the 9-Hole Peg Test. Spinal posture and axial rigidity were measured with a Spinal Mouse. Compared with the control group, a decrease in upper extremity functions (p < 0.001), decreased lumbar lordosis (p = 0.003), and posterior sacral tilt (p = 0.021) were determined in patients' group. Thoracic and lumbar mobility in the sagittal (all p < 0.001) and frontal planes (p = 0.004, p < 0.001) was found to be reduced in the patient group. A correlation was determined between upper extremity functions and lumbar mobility in the sagittal (p = 0.022, r= -0.362) and frontal planes (p = 0.045, r= -0.319) and lumbar lordosis (p = 0.048, r = 0.302). The results of this study demonstrated that altered spinal posture and increased axial rigidity were related with decreased upper extremity functions in patients with PD. There is a need for further studies to investigate effect of trunk-based therapies on upper extremity function in patients with PD.

Normal size of retropharyngeal lymph nodes in children on three dimensional magnetic resonance imaging.

Age-specific normal measurements or specific size criteria for retropharyngeal lymph nodes in children have not been defined. We aimed to determine the normal measurements and distribution of retropharyngeal lymph nodes on three-dimensional magnetic resonance imaging (3-D MRI) in children. In this retrospective study, we included 440 patients (213 girls) aged 0-17years who were admitted to our center with seizures and headaches and underwent brain and neck MRI with T2-sampling perfection with application-optimized contrasts using different flip angle evolution sequences. We evaluated the number, laterality, and level distribution of lateral and medial group lymph nodes according to the skull base-cervical vertebrae. For both groups, we measured the short and long diameters of the largest lymph node in the axial plane and the craniocaudal diameter in the sagittal plane. The short/long diameter ratios and volumes were determined. In 433 cases (98%), 1,554 lateral group lymph nodes were detected. Medial group lymph nodes were less common (7%). The lateral group was mostly bilateral, while the medial group was unilateral. Lateral group lymph nodes extended from the skull base-first cervical (C1) vertebral level to the C4, while the medial group extended from the C2 vertebral level to the C4. The mean axial short axis, axial long axis, and sagittal long axis diameters were 5.8mm, 10.1mm, and 15.5mm for the lateral group and 3.8mm, 7.6mm, and 10.8mm for the medial group, respectively. The findings of the study show that normally retropharyngeal lymph nodes are frequently seen in children and provide valuable information for lateral and medial lymph nodes depending on age.

SlugAtlas, a histological and 3D online resource of the land slugs Deroceras laeve and Ambigolimax valentianus.

Due to their distinctive anatomical characteristics, land slugs are appealing research subjects from a variety of angles, including stem cell biology, regeneration, embryonic development, allometry, and neurophysiology. Here we present SlugAtlas, an anatomical and histological online resource of the land slugs Deroceras laeve and Ambigolimax valentianus. The atlas is composed of series of histological sections on the horizontal, sagittal, and transversal planes for both species with 3D viewing tools of their major organs. The atlas was used in this work for a comparative analysis of the major organs and tissues of these two species. We provide a comprehensive histological description of them and an explanation of novel findings of unique features of their anatomy. For D. laeve, we additionally studied its ability for degrowth and regrowth, a feature that characterizes animals with high regeneration potential and obtained initial results on the study of the regeneration of its tail. SlugAtlas is a resource that is also built to accommodate future growth and, along with the experimental techniques that we have developed, will provide the foundation for research projects in a variety of biological domains.

Angular kinematics at minimum toe clearance in people with transtibial amputation using articulated and non-articulated prosthesis.

Subjects with unilateral transtibial amputation exhibit altered minimum toe clearance (MTC) depending on the ankle prosthesis used, possibly due to a limited prosthetic ankle angle. The aim of this study was to investigate the alterations in joints kinematics responsible for the changes in MTC when using an Articulating Hydraulic Ankle (AHA) compared to a Non Articulating Ankle (NAA) prosthesis. Twelve participants with unilateral transtibial amputation walked at self-selected speed on a 10 meter pathway. They used the same AHA and NAA prosthetic models and the prosthetic characteristics were unchanged except for the ankle mechanisms and, consequently, its mass. Data from MTC and hip, knee and ankle angles in the sagittal, frontal and transversal plane at the time of MTC were statistically analyzed with a paired sample t-test. The AHA prosthesis showed significantly higher MTC mean (AHA = 24.7 ± 9.6 mm vs. NAA = 17.4 ± 5.2 mm, P < 0.01) and variability (13.4 ± 9.6 mm vs. 6.7 ± 4.2 mm, P = 0.03) on the prosthetic limb than the NAA. A higher mean MTC could be explained by an increase in ankle angle dorsiflexion (AHA = -1.2 ± 2.6° vs. NAA = -2.9 ± 1.5°, P = 0.01) while the variability of the prosthetic MTC appears to be influenced by changes in prosthetic mass. The results of this study suggests that ankle dorsiflexion during swing and the mass of the prosthesis have a direct influence in mean MTC and its variability, respectively.

Clinical and Radiographic Outcomes With Minimum 2-Year Follow-up and Sub-Analysis of Navigation vs Non-Navigation for Hip Resurfacing.

The purpose of this study was to report the short-term clinical outcomes of hip resurfacing with navigation and the impact on accuracy of acetabular implant placement in both the frontal and sagittal planes. Data were retrospectively analyzed for patients who received hip resurfacing between 2010 and 2021. Eligible patients had postoperative radiographs and completed a minimum 2-year follow-up questionnaire for the following patient-reported outcomes: modified Harris Hip Score (mHHS), Harris Hip Score (HHS), Forgotten Joint Score (FJS), visual analog scale (VAS) score, satisfaction, and Hip Disability and Osteoarthritis Outcome Score, Joint Replacement (HOOS-JR). Hips were propensity matched in a 1:1 ratio based on the use of navigation, age, and body mass index. The percentage of hips that met the minimal clinically important difference (MCID) for mHHS and VAS score was noted. Component placement analysis was conducted based on the safe zones defined by Lewinnek and Callanan and the Relative Acetabular Inclination Limit. Seventy-six hips were matched, 38 per group. No differences were observed in patient-reported outcomes or the percentage of hips reaching MCID between the groups. The navigation group was 28.8 and 6.8 times more likely to be within the Callanan and Lewinnek safe zones, respectively. Based on the Relative Acetabular Inclination Limit, the navigation group was 3.1 and 6.4 times more likely to be within the 95% and 99% CI safe zones, respectively. Comparable improvements in patient-reported outcomes were observed in the two groups during a minimum 2-year follow-up. Navigation-assisted surgery enhances the accuracy of acetabular component positioning, with a higher likelihood of cup placement within the safe zones. [Orthopedics. 202x;4x(x):xx-xx.].

Accuracy and Efficiency of the Surgical-Guide-Assisted Fiber Post Removal Technique for Anterior Teeth: An Ex Vivo Study.

This study compared the accuracy and efficiency of different surgical-guide (SG)-assisted and freehand drilling techniques for removing fiber posts from maxillary anterior teeth performed by differently experienced operators. A fiber post was bonded to the root canal of 54 extracted maxillary anterior teeth. After mounting the teeth in the jaw models, SGs were designed by integrating cone-beam computed tomography (CBCT) and intraoral scanner data. Each SG included a custom sleeve. An experienced or inexperienced operator drilled the post using three different techniques: (i) SG-assisted incremental drilling at 2-3 mm (SG1), (ii) SG-assisted one-time drilling to a predetermined depth (SG2), and (iii) freehand incremental drilling without SG (FH; n = 9 in each group). Deviations in coronal, sagittal, and horizontal planes and the angle of deviation were measured. The SG1 and SG2 groups showed significantly smaller sagittal and horizontal deviations than the FH group, regardless of the operator's experience. The SG2 group had a significantly shorter working time than the SG1 and FH groups. In the FH group, the experienced operator required a significantly shorter working time than the inexperienced operator. SG-assisted drilling techniques enhanced the accuracy and efficiency of removing fiber posts from the anterior teeth, irrespective of the operator's experience.

Predicting Proximal Humerus Fracture Mechanical Complications: Are Computed Tomography Hounsfield Units the Answer?

The purpose was to determine whether computed tomography (CT) Hounsfield units (HU) as a proxy for bone quality can predict postoperative complications following surgical treatment of proximal humerus fractures. Sixty-six patients with 2-, 3-, or 4-part proximal humerus fractures who underwent surgical fixation at single institution and had complete radiographic data available were included. Radiographic measurements included the deltoid tuberosity index (DTI) on preoperative anterior-posterior shoulder radiographs, and the HU value from the surgical proximal humerus was determined by measuring the humeral head at the midaxial/coronal/sagittal CT image using a circle-type region of interest (≥35 mm2). Postoperative complications recorded were implant failure, development of osteonecrosis, nonunion, and acute periprosthetic fracture. Patients with and without complications were statistically compared, and binary logistic regression was performed to determine whether preoperative proximal humerus CT HU were predictive of complications. Eight patients (12.1%) developed 11 overall complications, with three patients experiencing multiple complications each. Complications included osteonecrosis (4), implant failure (5), nonunion (1), and acute periprosthetic fracture (1). No difference was observed in demographics or Neer or AO/OTA classification between those with and without complications. Patients with complications had markedly lower DTI and overall HU as well as HU in the coronal and sagittal planes. Regression analysis for average DTI demonstrated a higher DTI and had a 10 times decreased risk of complication (P = 0.040, odds ratio = -10.5, 95% confidence interval, 0.000 to 0.616). Regression analysis for average total HU also found a higher HU associated with a decreased risk of complications (P = 0.034, odds ratio = -0.020, 95% confidence interval, 0.980 to 0.962). Logistic regression analysis, including age, age-adjusted Charlson Comorbidity Index, mean DTI, and mean total HU, only found mean total HU to be notable within the model. CT HU may identify patients with poorer bone quality and thus help predict postoperative complications. Diagnostic Level III.

P14.16.A IS A LINAC WITH A 5MM MLC WIDTH REALLY A BARRIER TO IMPLEMENTING A HIGH-QUALITY COMPLEX SRS SERVICE?

Abstract BACKGROUND Stereotactic Radiosurgery (SRS) for patients with intracranial disease is increasing, especially for smaller and more numerous metastases. In England, Varian HyperArc using a Truebeam linac is nationally commissioned via benchmarking. HyperArc contains SRS-specific optimisation and non-coplanar VMAT delivery and is an attractive option due to its cost effectiveness compared with competing specialised platforms such as Elekta GammaKnife and Accuray CyberKnife. Depsite these benefits, the treatment of small targets or those with highly complex shapes is dominated by specialised platforms with a largely stated reason being perceived concern over delivered dosimetric certainty. This work assesses achievable dosimetric accuracy for complex SRS using Varian HyperArc suing a standard 120-leaf 5mm width MLC. MATERIAL AND METHODS Four patients with small and/or complex PTVs previously treated with CyberKnife at our institution were identified:26 metastases 24Gy/1f (PTV min. volume 0.01cc);5 metastases 24 Gy/1f (PTV min. volume 0.11cc);Pituitary adenoma 25Gy/1f (PTV width min. 5 mm near optics);Acoustic neuroma 21 Gy/3f (PTV width min. 3 mm near cochlea). Patients were re-planned with HyperArc using 4 arcs at 6FFF, emulating the prescription dose spillage (PDS) &amp; modified gradient index (mGI) achieved in the CyberKnife plans. Plans were produced in Eclipse v17.1, calculated using the AAA algorithm (v 17.1.0.1) on a 1mm calculation grid. The plan was then transferred to a CT scan of an in-house water equivalent phantom containing radiochromic EBT3 film in clinically meaningful coronal and sagittal dose planes and re-calculated. All plans were delivered under image guidance and the 2D film dosimetry was compared with the calculated dose from Eclipse using a global 5%/1mm (TH 20%) gamma test using well-established absolute dose film methodology in Sun Nuclear SNC Patient (v 8.2). RESULTS In all cases, HyperArc had very similar plan quality to CyberKnife, with maximum dose gradients between 20-23% of prescription dose per mm beyond the PTV (up to 5.8Gy/mm). Up to 1mm geometric offset was permitted to allow for imaging localization &amp; film registration uncertainty in the analysis. Mean gamma pass rates were 93.3% pre-alignment and 98.5% post-alignment. CONCLUSION The very high gamma pass rates achieved in this novel work illustrate excellent delivered dose accuracy for high-quality SRS plans. The use of a radiochromic film dosimetry allows for the demonstration of such accuracy using a standard Truebeam linac without the use of a high-definition MLC even for the smallest and most complex SRS targets. This work enables us to re-think previously held beliefs around perceived dosimetric limitations of multi-arc VMAT with a 5 mm MLC width for the delivery of high-quality SRS. Removing this barrier could start to bridge the existing gap in worldwide SRS service provision for patients.

The influence of endodontic treatment quality on periapical lesions' architecture in cone-beam computed tomography.

This study assessed the influence of root canal treatment quality on the architecture of periapical lesions. A total of 121 lesions were involved in this research. Two researchers analysed the surface of the lesions, diameters in three planes, volume and sphericity. The quality of root canal treatment was assessed with PESS index. Non-parametric statistical tests: Mann-Whitney and Spearman rank correlation coefficient were used in this research. Connected lesions of multirooted teeth spread in the coronal plane revealed a positive correlation with coronal seal and root canal filling homogenicity, however their spread in the sagittal plane showed a positive correlation only with root canal filling homogenicity. The quality of root canal treatment has an influence on the periapical lesions' architecture.