Bony Landmarks Research Articles

The influence of joint line restoration on functional outcome after primary total knee arthroplasty: A prospective study

ObjectiveRestoration of proper joint line position after primary total knee arthroplasty (TKA) is important for improved knee function and kinematics. We reviewed the magnitude of joint line alteration and the resulting effect on post-operative knee outcomes scores at one year follow-up. Materials and methods120 patients who underwent TKA for primary osteoarthritis knee were included. Assessment of joint line position before and after surgery was performed with the help of bony landmarks (excluding osteophytes): Medial Epicondyle Joint Line distance (MEJL), Lateral Epicondyle Joint Line distance (LEJL) and Fibula Head Joint Line distance (FHJL) were calculated. Post-operative knee function was assessed using ‘The Western Ontario and McMaster Universities Arthritis Index’ (WOMAC) and ‘Knee Society Score’ (KSS) at one year follow-up. ResultsJoint line elevation was observed in 104/120 (86.7%) patients and 16/120 (13.3%) patients had no joint line elevation. The mean joint line elevation was 3.00 (±2.13) mm. The patients were sub-classified into two study groups: Group A- Joint line elevation <5 mm and Group B- Joint line elevation ≥ 5 mm. The mean post-op one-year KSS score was significantly higher in patients in Group A compared to Group B (52.82 ± 7.564 vs. 40.73 ± 7.146; p < 0.001). The mean post-op one-year WOMAC score was lower in patients in Group A compared to Group B (65.51 ± 14.762 vs.75.64 ± 8.203) and the difference was statistically significant (p = 0.002). ConclusionElevation of joint line ≥5 mm from the pre-operative value has a negative impact on post-operative functional outcome in primary TKA.

CT and MRI measurements of tibial tubercle lateralization in patients with patellar dislocation were not equivalent but could be interchangeable.

To compare the values and the relationship of tibial tubercle lateralization measurements between computerized tomography (CT) and magnetic resonance imaging (MRI). Sixty patients with patellar dislocation who underwent both CT and MRI of the same knee joint from November 2021 to February 2022 were included in our study. The intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to evaluate the reliability of tibial tubercle-trochlear groove (TT-TG), tibial tubercle-Roman arch (TT-RA), and tibial tubercle-posterior cruciate ligament (TT-PCL) distance measurements. The values of CT and MRI measurements using the same bony landmarks were compared for the difference. Pearson correlation analysis and linear regression analysis were performed to assess the correlation between CT and MRI measurements. Finally, the estimated values obtained from the regression equation were compared with the actual values obtained from the radiological measurement to evaluate the accuracy of the equations. A total of 60 patients with patellar dislocation who underwent both CT and MRI of the same knee joint were included in this study. The included measurements showed excellent agreement with ICCs > 0.9. TT-TG distance measured on CT (19.5 ± 5.1mm) had a mean of 7.1mm higher than that on MRI (12.4 ± 4.7mm) (P < 0.001). The mean value of TT-RA distance was 22.5 ± 3.7mm on CT and 16.7 ± 4.9mm on MRI (P < 0.001), showing a mean difference of 5.8mm. The values of TT-TG distance measured by CT and MRI were significantly correlated (R = 0.5, P < 0.001). The values of TT-RA distance between these two modalities showed a better correlation than that of TT-TG distance (R = 0.6, P < 0.001). The interchange values of TT-TG distance and TT-RA distance between CT and MRI can be obtained using regression equations (TT-TG distance: y = 0.6x + 12.3; TT-RA distance: y = 0.5x + 14.4). The values of tibial tubercle lateralization measured by MRI may be underestimated compared with those measured by CT. Although the values measured on CT and MRI are not equivalent, the value in the other modality can be estimated. Therefore, an additional CT scan for tibial tubercle lateralization evaluation may not be necessary. Level II.

Visualising trends in dentition to lip mouth morphology using geometric morphometrics.

Linear measurements taken from bony landmarks are often utilised in facial approximation (FA) to estimate and plan the placement of overlying soft tissue features. This process similarly guides craniofacial superimposition (CFS) practices. Knowledge of how hard and soft tissue features spatially relate around the mouth region is, however, limited. Geometric morphometric techniques have thus been used to investigate size and shape variation in dentition-to-lip mouth morphology in a South African population. Twenty landmarks (twelve dentition, eight lips) were digitised, using cone-beam CT images of the anterior craniofacial complex in a Frankfurt/Frankfort position, for 147 individuals aged between 20 and 75 years. Principal Component Analysis and Canonical Variate Analysis established that much shape variation exists. A two-way ANOVA identified significant (p < 0.0001) population and sex variation with mouth shape. Black individuals presented with thicker lips, with the oral fissure aligning closely to the dental occlusion. Oral fissure position for white individuals corresponded to the inferior one-quarter (females) or one-sixth (males) of the maxillary central incisor crowns. Males presented larger dimensions than females, but females had a greater lip-to-teeth height ratio than their male counterparts. A pooled within-group regression analysis assessed the effect of age on the dentition and lips and found that it had a significant (p < 0.0001) impact on mouth shape. Ageing was associated with a reduced lip and teeth height, increased mouth width, and a lowered oral fissure and cheilion placement. The generated mean shape data, with metric guides, offer a visual and numerical guide that builds on existing FA and CFS standards, enhancing our understanding of hard and soft tissue relationships.

Magnetic resonance imaging study of the sciatic nerve variation in the pediatric gluteal region: Implications for the posterior approach of the sciatic nerve blockade.

In pediatric patients, the sciatic nerve is one of the most commonly blocked peripheral nerves during orthopedic procedures of the lower limb. Ultrasound guidance is the current standard for a successful localization of the sciatic nerve in the gluteal region. Relevant anatomical landmarks are also used to determine the nerve location when ultrasound is not available or inadequate. However, reports have demonstrated paucity of information regarding the sciatic nerve location and variation in the hip throughout pediatric development. This imaging study aimed to document and analyze the relative morphometric relationship of the sciatic nerve in the pediatric gluteal region throughout development. The location of the sciatic nerve in relation to bony landmarks was measured in 84 pediatric magnetic resonance imaging of patients aged 0.7-15.8 years. The sciatic nerve was identified medial to the most lateral point of greater trochanter at the level of ischial spine and the tip of coccyx. The strong positive correlation between sciatic nerve to landmark distances and age and stature demonstrated linear variation between sciatic nerve location with age and growth of children. To predict the nerve location in the gluteal region, regression equations using patient age were created, having implications for the posterior approach of the sciatic nerve blockade in children. Clinically significant differences were found between sexes, specifically in the older age group. Despite the small sample size of younger age group, this study is the first to document the morphometric changes of the sciatic nerve in the gluteal region across pediatric development and may be useful for providing confirmatory guidelines for nerve location when ultrasound is not accessible or cannot be utilized for practice.

A computer vision-based lifting task recognition method

Low-back musculoskeletal disorders (MSDs) are major cause of work-related injury among workers in manual material handling (MMH). Epidemiology studies show that excessive repetition is one of major risk factors of low-back MSDs. Thus, it is essential to monitor the frequency of lifting tasks for an ergonomics intervention. In the current field practice, safety practitioners need to manually observe workers to identify their lifting frequency, which is time consuming and labor intensive. In this study, we propose a method that can recognize lifting actions from videos using computer vision and deep neural networks. An open-source package OpenPose was first adopted to detect bony landmarks of human body in real time. Interpolation and scaling techniques were then applied to prevent missing points and offset different recording environments. Spatial and temporal kinematic features of human motion were then derived. These features were fed into long short-term memory networks for lifting action recognition. The results show that the F1-score of the lifting action recognition is 0.88. The proposed method has potential to monitor lifting frequency in an automated way and thus could lead to a more practical ergonomics intervention.

MODULATION OF THE CENTER OF MASS DURING AN AGILITY TASK

PURPOSE: The control of the center of mass (COM) of the body may have implications for injury and performance in athletes. This study aimed to identify potential factors that modulate the COM during an agility task. METHODS: Fifty college (n = 28) and high school (n = 22) female soccer players had the displacement of retro-reflective markers placed over select bony landmarks recorded using a 20-camera motion analysis system while performing a modified T-test. Using the transverse plane positional histories of the markers, the peak change in the linear momentum vector (ΔLMV) of the COM of the pelvis and the angle (ΔLMVA) it formed with the laboratory X or Y axis entering and exiting the two 90 degrees turns performed at the center cone were obtained. The step pattern and extremity used to make the turns were determined. A linear mixed model was used to compare the effects of turn number, limb, step pattern and playing level on the peak ΔLMV and ΔLMVA. RESULTS: An effect (p < .01) of turn number on the ΔLMV and ΔLMVA were noted. The ΔLMV entering turn 1 and 2 was -66.5 (± 3.5) and -8.7 (± 3.5) kg*m/s, respectively and exiting turn 1 and 2 they were 32.9 (± 3.4) and 40.8 (± 3.4) kg*m/s, respectively. The ΔLMVA entering turn 1 and 2 were 6 (± 2) and -24 (± 2) deg, respectively and exiting turn 1 and 2 they were 56 (± 2) and -67 (± 2) deg, respectively. An effect (p = .03) of step pattern on the ΔLMV exiting the turn was noted. The ΔLMV was 42.4 (± 3.8) and 34.1 (± 3.1) kg*m/s, for multi-step and single step patterns, respectively. Playing level and leg dominance did not influence the ΔLMV and ΔLMVA. CONCLUSIONS: The initial inertial state of the COM appears to be the primary factor affecting the control of the COM entering and exiting a turn. When exiting a turn, the step pattern used entering the turn appears to also affect the control of the COM.

Three-Dimensional Quantitative Evaluation of the Scapular Skin Marker Movements in the Upright Posture.

Motion capture systems using skin markers are widely used to evaluate scapular kinematics. However, soft-tissue artifact (STA) is a major limitation, and there is insufficient knowledge of the marker movements from the original locations. This study explores a scapular STA, including marker movements with shoulder elevation using upright computed tomography (CT). Ten healthy males (twenty shoulders in total) had markers attached to scapular bony landmarks and underwent upright CT in the reference and elevated positions. Marker movements were calculated and compared between markers. The bone-based and marker-based scapulothoracic rotation angles were also compared in both positions. The median marker movement distances were 30.4 mm for the acromial angle, 53.1 mm for the root of the scapular spine, and 70.0 mm for the inferior angle. Marker movements were significantly smaller on the superolateral aspect of the scapula, and superior movement was largest in the directional movement. Scapulothoracic rotation angles were significantly smaller in the marker-based rotation angles than in the bone-based rotation angles of the elevated position. We noted that the markers especially did not track the inferior movement of the scapular motion with shoulder elevation, resulting in an underestimation of the marker-based rotation angles.

Safe Region of Craniotomy to Access the Cerebellopontine Region by Retrosigmoid Approach: A Radiological and Anatomical Study.

Accurately positioning the sigmoid sinus (SS), transverse sinus (TS), and vertebral artery (VA) is significantly important during the retrosigmoid (RS) approach. This study aimed to use emissary vein and digastric point as landmarks in high-resolution computer topographic image to locate the SS, TS, and VA to help surgeons to avoid injuring these vascular structures during RS craniotomy. Computed topographic (CT) angiography images of 107 individuals were included, the measurement was performed on coronal, sagittal, and axis planes after the multiplanar reformation. Distance from the emissary vein and digastric point to the posterior boundary of the SS, inferior boundary of the TS were measured by CT angiography preoperatively and in the skull intraoperatively. The VA was also located by emissary vein and digastric point. No significant difference was identified between the distances measured in the CT and skull. Our findings provide anatomical information for locating the boundary of the SS, TS, and V3-VA based on the fixed bony landmarks. Verified by skull measurement, high-resolution CT scan is a cost-effective and reliable tool for identifying the location of the arteries and sinus, which could be widely used to guarantee the safety of RS approach craniectomy.

Morphometric Study on Types of Asterion in Dry Human Skull of Nepalese Origin

Introduction: The asterion is important bony landmark of skull important for surgical approach to the posterior cranial fossa. The variation is type of asterion is due to presence or absence of lambdoidal suture, parietomastoid suture and occipitomastoid suture. Asterion is starry or triangular depression located 2.5cm behind the upper part of root of ear. Asterion is meeting point of lambdoidal suture, parietomastoid suture and occipitomastoid suture. Materials and Methods: Altogether 26 dry adult human skulls were collected from Department of Anatomy at School of Basic Sciences in Chitwan Medical College for research. Gender and ethnicity were undefined. All damaged skull and newborns are excluded. Both sides of skull were studied for location and type of asterion. The types of asterion were noted by observing the presence or absence of all three sutures. Photograph were taken and studied. Statistical analysis was done using SPSS 17. Results: Twenty-six human skulls of unknown gender were examined. Two types of asterion were observed. The type I asterion was 88.5 percent and type II asterion was 11.5 percent on both side of skull. Conclusion: we believe that there are different types of asterion present in human skull. Asterion is the important surgical landmark. Thereby, the finding may be helpful in surgical approach and intervention.

The Glenoid Vault Outer Cortex (GVOC) radiological reference for shoulder arthroplasty evaluated in aging scapulae

BackgroundAccurate glenoid component positioning is an important determinant of outcome in a shoulder arthroplasty surgery. Optimal glenoid placement is determined using bony landmarks of the scapula. The Glenoid Vault Outer Cortex (GVOC) has been recently described as a new, more accurate radiological reference. This has, however, only been evaluated against current standard references in young patients. Further investigation of the GVOC in older patients is therefore warranted. We, therefore, evaluated the effect of aging on the accuracy and stability of the GVOC, in determining glenoid anatomy as compared to the commonly used Scapular Border (SB) plane. MethodsComputed tomography imaging of 129 individual scapulae was obtained retrospectively from a cohort of patients who had undergone either total body or region-specific computed tomography imaging which included the shoulder region. This comprised of 35 males and 33 females (64 and 65 scapulae respectively) who were aged from 30 to 92 years. Imaging of 54 scapulae was from patients aged ≥60 years. The accuracy of the GVOC plane was then assessed against the SB plane. ResultsIn all patients, the mean difference between estimates using the GVOC plane and the GR (actual) was 2.2° (standard deviation [SD], 4.2) for version, and 1.8° (SD, 4.9) for inclination (P < .001). This contrasted with values of 7.6° (SD, 7.6) for version, and 22.9° (SD, 10.8) for inclination when using the SB reference plane (P < .001). Within the group aged ≥60 years, the mean difference between estimates using the GVOC plane and the glenoid rim (actual) was 3.2° (SD, 4.7) for version and 1.9° (SD, 3.1) for inclination, (P < .001). This contrasted to 10.0° (SD, 7.2) for version, and 23.4° (SD, 10.7) for inclination when using the SB plane (P < .001).Separately it was noted that the GVOC’s relationship to the glenoid rim remained constant throughout aging as opposed to the SB which changed significantly over time effecting estimates of glenoid retroversion. ConclusionsThe GVOC is a new plane of reference developed specifically for the use in shoulder arthroplasty. It is shown to be more accurate and stable in the aging scapulae than the currently used SB plane. The future development of guides and planning softwares that utilize the GVOC may provide an important opportunity for improved accuracy and outcome in shoulder arthroplasty.

Effects Of Active Release Technique and Active Isolated Stretching on Muscles of Upper Cross Syndrome

Upper cross syndrome is a condition in which there exist a muscle imbalance in upper quadrant, involving weakness of some muscles and tightness of others. In UCS, levator scapulae muscle, upper fibers of trapezius muscle, and pectoralis minor get stiff and shortened from their original length occasionally involving pectoralis major muscle. Objectives: To compare the effect of Active release technique and active isolated stretching on the muscles of upper cross syndrome. Methods: This study was a single blinded randomized clinical trial. Muscle length measurement by Vernier calipers and measuring tape between standard bony landmarks, NDI (neck disability index), Cervical rotation ROM, Cranio-vertebral angle &amp; Numeric Pain Rating Scale (NPRS) tools for screening will be used for data collection. Recorded values were analyzed for any change using SPSS 21.0 version. Results: In ART the mean value of NPRS was 2.21 ± 1.49 and in AIS was 2.31 ± 1.35. For ART group the mean NDI score was 15.12 ± 8.83 and for AIS group was 16.1250 ± 5.3898. The mean of cranio-vertebral angle in AIS group was 47.2125 ± 1.9373 and in ART group was 48.1819 ± 1.6483 which is nearer to normal CV angle. Conclusions: The study concluded that both Active release technique (ART) and Active isolated stretching (AIS) are effective methods of treatment. It was indicated that Active release technique (ART) was helpful in pain relief, improving range, cranio-vertebral angle, muscle length and functional status in subjects with Upper-cross syndrome (UCS).

Comparison of body segment models for female high jumpers utilising DXA images

In motion analysis of sport competitions, the question is often about the most convenient choice for defining the segment endpoints when no visible landmarks can be used. The purpose of the present study was to determine the location of the body centre of mass (CoM) of female high jumpers by using a high accuracy reaction board and two different segment models: Dempster (1955) and de Leva (1996). Digitising the bony landmarks from the images of dual energy x-ray absorptiometry (DXA) and overhead digital camera were used to compare the digitising accuracy. The location of the CoM determined by a reaction board was 55.88 ± 0.52% of subjects’ body height. The segment model of Dempster digitized from DXA images (56.66 ± 0.50%) differed from the reference values of reaction board (p = 0.004), whereas the model of de Leva (56.06 ± 0.61%) showed no significant difference. The model of de Leva adjusted for female subjects differed only slightly (0.32%), thus, providing appropriate model for female high jumpers. Since the digitised bony landmarks in the DXA images are obviously very close to the correct locations, the differences in results between the segment models and reaction board is most likely due to inaccuracies in the model itself and/or generalisation of one model to different body structures. When the segment landmarks were estimated without any markers on the body, the results did not differ much from the DXA results.

Anatomical Study of the Innervation of Triangular Fibrocartilage Complex and Distal Radioulnar and Radiocarpal Joints: Implications for Denervation

Open and percutaneous denervation is an emerging technique for joint pain. This study investigated the course and distribution of the articular branches innervating the triangular fibrocartilage complex (TFCC), distal radioulnar joint (DRUJ), and radiocarpal joint (RCJ) relative to bony and soft tissue landmarks to guide wrist denervation procedures. Fourteen formalin-embalmed specimens were serially dissected to expose the origin, course, and distribution of articular branches innervating the TFCC, DRUJ, and RCJ. Bony and soft tissue landmarks to localize each articular branch were documented and visualized on a 3-dimensional reconstruction of the bones of the distal forearm and hand. The TFCC was innervated by articular branches from the posterior interosseus nerve (10 of 14 specimens), dorsal cutaneous branch of the ulnar nerve (14 of 14 specimens), palmar cutaneous branch of the ulnar nerve (12 of 14 specimens), and medial antebrachial cutaneous nerve (9 of 14 specimens). The DRUJ was innervated by the posterior interosseus nerve (9 of 14 specimens) and anterior interosseus nerve (14 of 14 specimens). The RCJ was innervated by the posterior interosseus nerve (14 of 14 specimens), superficial branch of the radial nerve (5 of 14 specimens), lateral antebrachial cutaneous nerve (14 of 14 specimens), and palmar cutaneous branch of the median nerve (10 of 14 specimens). Multiple nerves were found to innervate the TFCC, DRUJ, and RCJ. The relationship of anatomical landmarks to specific articular branches supplying the TFCC, DRUJ, and RCJ can inform selective denervation procedures based on the structural origin of pain. The detailed documentation of the spatial relationship of the nerve supply to the wrist provides clinicians with the anatomical basis to optimize current, and develop new denervation protocols to manage chronic wrist pain.

Effectiveness of temporal subtraction computed tomography images using deep learning in detecting vertebral bone metastases

PurposeTo assess the clinical effectiveness of temporal subtraction computed tomography (TS CT) using deep learning to improve vertebral bone metastasis detection. MethodThis retrospective study used TS CT comprising bony landmark detection, bone segmentation with a multi-atlas-based method, and spatial registration of two images by a log-domain diffeomorphic Demons algorithm. Paired current and past CT images of 50 patients without vertebral metastasis, recorded during June 2011–September 2016, were included as training data. A deep learning-based method estimated registration errors and suppressed false positives. Thereafter, paired CT images of 40 cancer patients with newly developed vertebral metastases and 40 control patients without vertebral metastases were evaluated. Six board-certified radiologists and five radiology residents independently interpreted 80 paired CT images with and without TS CT. ResultsRecords of 40 patients in the metastasis group (median age: 64.5 years; 20 males) and 40 patients in the control group (median age: 64.0 years; 20 males) were evaluated. With TS CT, the overall figure of merit (FOM) of the board-certified radiologist and resident groups improved from 0.848 to 0.876 (p = 0.01) and from 0.752 to 0.799 (p = 0.02), respectively. The sub-analysis focusing on attenuation changes in lesions revealed that the FOM of osteoblastic lesions significantly improved in both the board-certified radiologist and resident groups using TS CT. The sub-analysis focusing on lesion location showed that the FOM of the resident group significantly improved in the vertebral arch (p = 0.04). ConclusionsTS CT was effective in detecting bone metastasis by both board-certified radiologists and radiology residents.

Comparison of Arthroscopic versus Open Placement of the Fibular Tunnel in Posterolateral Corner Reconstruction.

Precise fibular tunnel placement in posterolateral corner (PLC) reconstruction is crucial in restoring rotational and lateral stability. Despite the recent progress of arthroscopic PLC reconstruction techniques, landmarks for arthroscopic fibular tunnel placement and a comparison to open tunnel placement have not yet been described. This study aimed to (1) identify reasonable soft-tissue and bony landmarks, which can be identified by either arthroscopy, fluoroscopy, or open surgery in anatomic fibular tunnel placement and (2) to compare accuracy and reliability of arthroscopic fibular tunnel placement with open surgery. In a retrospective study, 41 magnetic resonance images (MRIs) of the knee were analyzed with emphasis on distances of an ideal anatomic fibular tunnel to 11 soft-tissue and bony landmarks. Subsequently, in eight cadaver knees, the ideal fibular tunnel was created arthroscopically and with a standard open technique from antero-latero-inferior to postero-medio-superior with a 2-mm K-wire. Positions of both tunnels were compared on postinterventional computed tomography scans. Based on MRI measurements, the anatomic tunnel entry should be 14.50 (±2.18) mm distal to the tip of the fibular styloid and 10.76 (±1.37) mm posterior to the anterior edge of the fibula. The anatomic fibular tunnel exit was located 12.89 (±2.35) mm below the tip of the fibular head. Arthroscopic fibular tunnel placement was reliable in all cases. Instead, in five out of the eight cases with open surgery, the fibular tunnel crossed the defined safety distance to the closest cortical edge/tibiofibular joint (distance < 8 mm). Reliable soft-tissue and bony landmarks of the fibular head allow arthroscopic anatomic fibular tunnel placement in PLC surgery, which shows a lower risk of tunnel malposition compared with open surgical techniques. Future studies will have to show whether clinical results of arthroscopic PLC reconstruction are in line with this study's technical results. Level III.

Poster 221: Application of Machine Learning to Diagnose Patellar Instability on MRI Using a Data-Driven Model

Objectives:Patellar instability has multiple anatomic risk factors including trochlear dysplasia, patella alta and tuberosity lateralization. However, the exact contribution of each factor on patellar stability has not been clearly delineated due to the fact that 1) each abnormality exists along a spectrum that varies between individuals, 2) multiple measurements exist to describe each risk factor, and 3) the additive effects of these morphological abnormalities are not yet understood. The advent of modern machine learning techniques allows us the opportunity to extract predictive insights by detecting complex patterns underlying health data. We aimed to apply machine learning to differentiate between knee MRI measurements of patients with and without patellar instability to determine the complex relationships across variables that contribute to patellar instability.Methods:Utilizing an institutional database, knee MRIs of patients between the ages 18 to 40 at the time of imaging with a diagnosis of recurrent patellar instability were identified. Age and sex matched controls were selected from a database of MRIs with a diagnosis of meniscal tear for comparison. 26 standard measurements that have been used to describe trochlear dysplasia, patella alta, and tuberosity lateralization were performed on each knee, including bony and cartilaginous landmarks for each measurement when applicable. Using these measurements, 3 categories of machine learning methods were performed, including interpretable model-based methods (linear model, decision tree, random forest, and gradient boosted tree), non-interpretable model-based methods (neural network, and support vector machine [SVM]), and instance-based method (k-nearest neighbor [KNN]). A split validation method was used to divide the entire dataset into train, validation, and test subsets with an 80:10:10 split-ratio.Results:130 knees with patellar instability (47M, 83F) were included in this study and compared with 130 age- and sex-matched control knees. Table 1 summarizes the performance of each method on the test subset. The decision tree achieved the highest overall accuracy among the interpretable model-based methods, followed by SVM, and KNN among non-interpretable model-based and instance-based methods, respectively. Figure 1 depicts the decision tree model, demonstrating that bisect offsect measurement >72.1%, followed by length of patello-trochlear overlap <= 1.35mm, and cartilaginous trochlear depth <= 3.18mm predicted the presence of patellar instability with an accuracy of 84.62%.Conclusions:We present a novel approach to identify patellar instability from MRI measurements, in which an interpretable model-based machine learning method (decision tree) achieved the highest overall performance. Furthermore, patellar lateralization as reflected by bisect offset, patella alta as reflected by patellotrochlear overlap, and cartilaginous trochlear depth indicating dysplasia were found to identify knees with patellar instability. Application of this model and the utilization of uniform measurements can potentially improve the diagnostic accuracy of patellar instability from MRI images. Prospective clinical studies are recommended to further validate this model for its utility in the prediction of patellar instability.Table 1.Diagnostic Performance of machine learning methods on the test subgroupFigure 1.Decision tree model

Paper 20: The Relationship of Schottle’s Point to the Medial Distal Femoral Physis: A Digitally Reconstructed Radiograph and 3-Dimensional Computed Tomography Study

Objectives:There is significant controversy regarding ideal medial patellofemoral ligament reconstruction (MPFLR) femoral tunnel position in the pediatric setting. The authors identified 3 main gaps in knowledge. First, the position of the radiographic MPFLR start point (Schottle’s point) relative to the medial distal femoral epiphysis is not well defined. Second, although anatomic studies have suggested tunnel trajectories that avoid physeal contact, these trajectories are not based upon the widely used Schottle’s point, providing limited intraoperative utility. Third, prior studies provide conflicting data regarding position of the MPFL origin relative to the distal femoral physis, particularly in younger patients. The purpose of this study was to determine the proximity of Schottle’s point to the medial distal femoral physis and the medial epicondyle using a digitally reconstructed radiographs (DRR) and three-dimensional computed tomography (CT) models.Methods:The institutional picture archiving and communication system (PACS) was queried for CT imaging studies of pediatric knees with open physes. CT data were imported to a Python based, open-source image processing software and were transformed to create true lateral digitally reconstructed radiographs (DRR) (Figure 1) and 3-dimensional (3D) renderings of the distal femur (Figure 2). Schottle’s point and the medial epicondyle were registered using fiducial markers and 3D distance measurements were then obtained from Schottle’s point on the medial cortex to 1) the medial epicondyle, 2) the physeal point directly superior to Schottle’s point, and 3) the shortest distance to the medial physis on the cortical surface. A 6-millimeter circle was used to simulate reaming diameter and physeal intersections were tabulated.Results:49 pediatric knee CT scans with open physes were included in the data. Average patient age was 13.0 ± 2.3 years (range: 6-17 years). Mean minimum distance from the medial physis to Schottle’s point was 9.9 mm ± 3.0mm (range: 3.4-16.1 mm) (Figure 3). In 49 of 49 cases (100%), Schottle’s point was distal to the physis. Schottle’s point was localized at a mean distance of 7.5mm ± 3.14mm posterior to the medial epicondyle and 6.1mm ± 2.9mm superior to the medial epicondyle. Using a 6mm reaming diameter, 3 (6%) femurs in our study would have violation of the medial distal femoral physis. Moving the start point 3mm distally would result in 0 of 49 (0%) having physeal injury.Conclusions:Historically, characterizing the position of the origin of the MPFL on the medial condyle relative to the medial distal femoral physis has been challenging. Prior cadaveric studies have suggested the MPFL originates proximal to the physis in younger patients (<7 years). However, more recent cadaveric studies have challenged this idea, finding the bony landmarks of the MPFL origin to be distal to the physis. Although these studies have sparked significant discussion regarding the pediatric MPFL origin, they have small numbers of specimens. Using a more surgically relevant approach, the present study demonstrates that Schottle’s point is consistently distal to the distal femoral physis.Prior studies have suggested anterior and distal drill trajectories that may minimize physeal injury. Although useful, these studies do not assess drilling path relative to the commonly used radiographically identified starting point, Schottle’s point. The present study complements this prior work by addressing the radiographic start point upon which the drill trajectory is based intraoperatively. Based on the present study, the use of Schottle’s point without distalization would lead to physeal injury in 6% of cases.Further, prior cadaveric anatomic studies are subject to limitations of the availability and expense of pediatric specimens and are therefore limited to small sample sizes. The methodology of the present study, by using readily available fine cut CT data, is not subject to such constraints. The present investigation offers a larger sample size than any previously published pediatric MPFL anatomic study and uses a highly accurate and repeatable methodology. This unique methodology may be more broadly applicable to the study of pediatric procedures near the physis.The radiographically defined surgical start point for MPFL femoral tunnel placement (Schottle’s point), is consistently distal to the medial distal femoral physis. Mean minimum distance from Schottle’s point to the physis on the medial cortex is 9.9mm. Using Schottle’s point for the start of tunnel drilling leads to physis violation in 6% of cases, when using a 6mm reamer. Distalization of the start point by 3mm leads to avoidance of physeal injury in all cases.Figure 1.Digitally Reconstructed Radiograph with Identification of Schottle’s PointFigure 2.3D Rendering with Physeal Distance MeasurementFigure 3.Saggital Plane Plot of Schottle’s Point and Closest Point on Medial Physis

John Charnley Award: Deep Learning Prediction of Hip Joint Center on Standard Pelvis Radiographs.

Accurate hip joint center (HJC) determination is critical for preoperative planning, intraoperative execution, clinical outcomes after total hip arthroplasty, and commonly used classification systems in primary and revision hip replacement. However, current methods of preoperative HJC estimation are prone to subjectivity and human error. The purpose of the study was to leverage deep learning (DL) to develop a rapid and objective HJC estimation tool on anteroposterior (AP) pelvis radiographs. Radiographs from 3,965 patients (7,930 hips) were included. A DL model workflow was created to detect bony landmarks and estimate HJC based on a pelvic height ratio method. The workflow was utilized to conduct a grid-search for optimal nonspecific, sex-specific, and patient-specific (using contralateral hip) pelvic height ratios on the training/validation cohort (6,344 hips). Algorithm performance was assessed on an independent testing cohort for HJC estimation comparison. The algorithm estimated HJC for the testing cohort at a rate of 0.65 seconds/hip based on features in AP radiographs alone. The model predicted HJC within 5 mm of error for 80% of hips using nonspecific ratios, which increased to 83% with sex-specific and 91% with patient-specific pelvic height ratio models. Mean error decreased utilizing the patient-specific model (3.09 ± 1.69 mm, P < .001). Using DL, we developed nonspecific, sex-specific, and patient-specific models capable of estimating native HJC on AP pelvis radiographs. This tool may provide clinical value when considering preoperative component position in patients planned to undergo THA and in reducing the subjective variability in HJC estimation. Diagnostic, level IV.

Morphology of the groove of the inferior petrosal sinus: application to better understanding variations and surgery of the skull base.

Although adequate venous drainage from the cranium is imperative for maintaining normal intracranial pressure, the bony anatomy surrounding the inferior petrosal sinus and the potential for a compressive canal or tunnel has, to our knowledge, not been previously investigated. One hundred adult human skulls (200 sides) were observed and documented for the presence or absence of an inferior petrosal groove or canal. Measurements were made and a classification developed to help better understand their anatomy and discuss it in future reports. We identified an inferior petrosal sinus groove (IPSG) in the majority of specimens. The IPSG began anteriorly where the apex of the petrous part of the temporal bone articulated with the sphenoid part of the clivus, traveled posteriorly, in a slight medial to lateral course, primarily just medial to the petro-occipital fissure, and ended at the anteromedial aspect of the jugular foramen. When the IPSGs were grouped into five types. In type I specimens, no IPSG was identified (10.0%), in type II specimens, a partial IPSG was identified (6.5%), in type III specimens, a complete IPSG (80.0%) was identified, in type IV specimens, a partial IPS tunnel was identified (2.5%), and in type V specimens, a complete tunnel (1.0%) was identified. An improved knowledge of the bony pathways that the intracranial dural venous sinuses take as they exit the cranium is clinically useful. Radiological interpretation of such bony landmarks might improve patient diagnoses and surgically, such anatomy could decrease patient morbidity during approaches to the posterior cranial fossa.

The Utility of Lesser Trochanter Version to Estimate Femoral Anteversion in Total Hip Arthroplasty: A Three-Dimensional Computed Tomography Study

Objective: Femoral anteversion is an important parameter that can prevent complication following total hip arthroplasty (THA) caused by improper positioning of the implant. However, assessing the femoral anteversion can be challenging in situations with significant defect of the femoral neck. In this study, the lesser trochanter version was nominated as alternative parameter to femoral anteversion. So, the main objective of this study is to determine whether the femoral anteversion correlates with the lesser trochanter version. Design: Retrospective study. Methods: Three-dimensional images of 100 femora were generated and their femoral anteversion and lesser trochanter version was measured. Correlation between the parameters were calculated. Results: The mean lesser trochanter version was 38.54° ± 7.86° (mean ± SD), while the mean femoral anteversion was 11.84° ± 10.06°. The lesser trochanter version was inversely correlated with the femoral anteversion with a correlation coefficient of −0.72. Conclusions: The lesser trochanter should be considered as an additional bony landmark to assess proper implant positioning in THA.