Radiographic Landmarks Research Articles

Automated diagnosis of flatfoot using cascaded convolutional neural network for angle measurements in weight-bearing lateral radiographs.

Diagnosis of flatfoot using a radiograph is subject to intra- and inter-observer variabilities. Here, we developed a cascade convolutional neural network (CNN)-based deep learning model (DLM) for an automated angle measurement for flatfoot diagnosis using landmark detection. We used 1200 weight-bearing lateral foot radiographs from young adult Korean males for the model development. An experienced orthopedic surgeon identified 22 radiographic landmarks and measured three angles for flatfoot diagnosis that served as the ground truth (GT). Another orthopedic surgeon (OS) and a general physician (GP) independently identified the landmarks of the test dataset and measured the angles using the same method. External validation was performed using 100 and 17 radiographs acquired from a tertiary referral center and a public database, respectively. The DLM showed smaller absolute average errors from the GT for the three angle measurements for flatfoot diagnosis compared with both human observers. Under the guidance of the DLM, the average errors of observers OS and GP decreased from 2.35° ± 3.01° to 1.55° ± 2.09° and from 1.99° ± 2.76° to 1.56° ± 2.19°, respectively (both p < 0.001). The total measurement time decreased from 195 to 135min in observer OS and from 205 to 155min in observer GP. The absolute average errors of the DLM in the external validation sets were similar or superior to those of human observers in the original test dataset. Our CNN model had significantly better accuracy and reliability than human observers in diagnosing flatfoot, and notably improved the accuracy and reliability of human observers. • Development of deep learning model (DLM) that allows automated angle measurements for landmark detection based on 1200 weight-bearing lateral radiographs for diagnosing flatfoot. • Our DLM showed smaller absolute average errors for flatfoot diagnosis compared with two human observers. • Under the guidance of the model, the average errors of two human observers decreased and total measurement time also decreased from 195 to 135min and from 205 to 155min.

CORRELATION ANALYSIS OF DIFFERENT PELVIC TILT DEFINITIONS: A PRELIMINARY STUDY

Pelvic tilt (PT) is always described as the pelvic orientation along the transverse axis, yet four PT definitions were established based on different radiographic landmarks: anterior pelvic plane (PTa), the centres of femoral heads and sacral plate (PTm), pelvic outlet (PTh), and sacral slope (SS). These landmarks quantify a similar concept, yet understanding of their relationships is lacking. Some studies referred to the words “pelvic tilt” for horizontal comparisons, but their PT definitions might differ. There is a demand for understanding their correlations and differences for education and research purposes.This study recruited 105 sagittal pelvic radiographs (68 males and 37 females) from a single clinic awaiting their hip surgeries. Hip hardware and spine pathologies were examined for sub-group analysis. Two observers annotated four PTs in a gender-dependent manner and repeated it after six months. The linear regression model and intraclass correlation coefficient (ICC) were applied with a 95% significance interval.The SS showed significant gender differences and the lowest correlations to the other parameters in the male group (−0.3&lt; r &lt;0.2). The correlations of SS in scoliosis (n = 7) and hip implant (female, n = 18) groups were statistically different, yet the sample sizes were too small. PTm demonstrated very strong correlation to PTh (r &gt; 0.9) under the linear model PTm = 0.951 × PTh - 68.284.The PTm and PTh are interchangeable under a simple linear regression model, which enables study comparisons between them. In the male group, SS is more of a personalised spinal landmark independent of the pelvic anatomy. Female patients with hip implant may have more static spinopelvic relationships following a certain pattern, yet a deeper study using a larger dataset is required. The understanding of different PTs improves anatomical education.

AUTOMATED LANDMARK DETECTION IN FUNCTIONAL LATERAL RADIOGRAPHS USING DEEP LEARNING

Evaluation of patient specific spinopelvic mobility requires the detection of bony landmarks in lateral functional radiographs. Current manual landmarking methods are inefficient, and subjective. This study proposes a deep learning model to automate landmark detection and derivation of spinopelvic measurements (SPM).A deep learning model was developed using an international multicenter imaging database of 26,109 landmarked preoperative, and postoperative, lateral functional radiographs (HREC: Bellberry: 2020-08-764-A-2). Three functional positions were analysed: 1) standing, 2) contralateral step-up and 3) flexed seated. Landmarks were manually captured and independently verified by qualified engineers during pre-operative planning with additional assistance of 3D computed tomography derived landmarks. Pelvic tilt (PT), sacral slope (SS), and lumbar lordotic angle (LLA) were derived from the predicted landmark coordinates. Interobserver variability was explored in a pilot study, consisting of 9 qualified engineers, annotating three functional images, while blinded to additional 3D information. The dataset was subdivided into 70:20:10 for training, validation, and testing.The model produced a mean absolute error (MAE), for PT, SS, and LLA of 1.7°±3.1°, 3.4°±3.8°, 4.9°±4.5°, respectively. PT MAE values were dependent on functional position: standing 1.2°±1.3°, step 1.7°±4.0°, and seated 2.4°±3.3°, p&lt; 0.001. The mean model prediction time was 0.7 seconds per image. The interobserver 95% confidence interval (CI) for engineer measured PT, SS and LLA (1.9°, 1.9°, 3.1°, respectively) was comparable to the MAE values generated by the model.The model MAE reported comparable performance to the gold standard when blinded to additional 3D information. LLA prediction produced the lowest SPM accuracy potentially due to error propagation from the SS and L1 landmarks. Reduced PT accuracy in step and seated functional positions may be attributed to an increased occlusion of the pubic-symphysis landmark. Our model shows excellent performance when compared against the current gold standard manual annotation process.

ACROMIAL MORPHOLOGY IS A RISK FACTOR FOR UNIDIRECTIONAL POSTERIOR SHOULDER INSTABILITY

Acromial morphology has been implicated as a risk factor for unidirectional posterior shoulder instability. Studies utilising plain film radiographic landmarks have identified an increased risk of posterior shoulder dislocation in patients with higher acromion positioning. The aims of this study were to develop a reproducible method of measuring this relationship on cross sectional imaging and to evaluate acromial morphology in patients with and without unidirectional posterior shoulder instability.We analysed 24 patients with unidirectional posterior instability. These were sex and age matched with 61 patients with unidirectional anterior instability, as well as a control group of 76 patients with no instability. Sagittal T1 weighted MRI sequences were used to measure posterior acromial height relative to the scapular body axis (SBA) and long head of triceps insertion axis (LTI). Two observers measured each method for inter-observer reliability, and the intraclass correlation coefficient (ICC) calculated.LTI method showed good inter-observer reliability with an ICC of 0.79. The SBA method was not reproducible due suboptimal MRI sequences. Mean posterior acromial height was significantly greater in the posterior instability group (14.2mm) compared to the anterior instability group (7.7mm, p=0.0002) as well when compared with the control group (7.0mm, p&lt;0.0001). A threshold of 7.5mm demonstrated a significant increase in the incidence of posterior shoulder instability (RR = 9.4).We conclude that increased posterior acromial height is significantly associated with posterior shoulder instability. This suggests that the acromion has a role as an osseous restraint to posterior shoulder instability.

A Novel Technique of Arthroscopic Femoral Tunnel Placement during Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation.

Recurrent patellar dislocation is a commonly encountered patellofemoral disease. Prompt surgical intervention is indicated for recurrent dislocation to restore patellofemoral stability. As one of the most preferred procedures, medial patellofemoral ligament (MPFL) reconstruction has been implemented on a large scale. Femoral tunnel placement remains a crucial technical issue during MPFL reconstruction and is critical to ensure the isometry and proper tension of the graft. Currently, visual-palpatory anatomic landmarks and fluoroscopy-guided radiographic landmarks comprise the main approaches to intraoperative femoral tunnel positioning. However, the accuracy of both methods has been questioned. This article introduces an arthroscopic femoral tunnel placement technique. Apart from traditional anteromedial and anterolateral portals, two auxiliary arthroscopic portals are specially designed. The adductor tubercle, the medial epicondyle and the posterior edge are selected as main anatomic landmarks and are directly visualized in sequence under arthroscope. The relative position between the femoral attachment of the MPFL and the three landmarks is measured on preoperative three-dimensional computed tomography, providing semi-quantified reference for intraoperative localization. This technique achieves minimally invasive tunnel placement without X-ray exposure, and especially suits obese patients for whom palpatory methods are difficult to perform.

The "V" Sign: A Reliable Anatomic and Radiographic Landmark for Posterior Percutaneous S1 Screw Placement.

Sacral (S1) pedicle screw misplacement in posterior percutaneous fixation (PPF) can be related to anatomical variability and a lack of reliable radiographic landmarks. This study highlights a reproducible anatomical landmark (the "V" sign) for the safe localization of the S1 pedicle entry point under fluoroscopy. Human cadavers (n = 14) were dissected for the anatomical description of the "V" landmark and its relationship with the entry point of the S1 pedicle screw. The "V" landmark was defined medially by the lateral border of the superior articulating process of S1 and laterally by the posterior projection of the sacral ala. The mean distance was measured between the bottom point of the "V" landmark and the anatomical entry point to the S1 pedicle (V-S1 entry point distance). A similar measurement was conducted on computed tomography (CT) scans of 135 patients who underwent PPF using the "V" sign as a landmark for S1 pedicle screw placement (270 screws). These were retrospectively evaluated for appropriateness of S1 screw entry points and for proper S1 screw alignment and breaches. In the 14 cadavers, irrespective of the laterality and sex, the V-S1 entry point distance averaged 11.7 mm. On the medial-lateral axis, all entry points converged within 2 mm of a vertical line intersecting the base of the "V." Additionally, the CT scan analysis (135 patients, 270 screws) revealed an optimal entry point for 100% of the screws and a 3.3% (n = 9 screws) breach rate. Six of the 9 identified breaches were minor, and only 1 (0.4% of the 270 screws) warranted revision. The "V" sign serves as a reliable anatomical and radiographic landmark for identifying the S1 pedicle entry point under fluoroscopic guidance. This landmark can help surgeons overcome the radiographic ambiguity of the sacral anatomy and ultimately reduces the rate of S1 pedicle screw misplacement. Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Achieving Optimal Central Venous Catheter Position: Evaluation of Radiographic Landmarks for Accuracy and Inter-observer Reliability in Locating the Cavoatrial Junction

Achieving Optimal Central Venous Catheter Position: Evaluation of Radiographic Landmarks for Accuracy and Inter-observer Reliability in Locating the Cavoatrial Junction

Sagittal mechanical ratio: A novel technique to define sagittal alignment of the femur independent of distal anatomic landmarks

BackgroundRadiographic measurements to study sagittal alignment in the setting of knee are frequently difficult to evaluate due the presence of a prosthesis or implant that obscures traditional radiographic landmarks. In this paper we present a novel method of determining sagittal femoral alignment in the presence of obscuring implants. Methods98 full-length femoral radiographs were reviewed and divided into two groups. In Group 1, the Distal Mechanical Point (DMP) was used to calculate the Distal Mechanical Ratio (DMR), defined as the ratio of the linear distance from the DMP to the anterior cortical axis divided by the distance from the anterior cortical axis to posterior condylar cortex. In group 2, the sagittal mechanical axis was measured using the true DMP (tDMP) and then separately measured using the DMR to find the calculated DMP (cDMP), and the angular variance between the calculated (cSMA) and true (tSMA) sagittal mechanical axis was calculated, as well as the linear distance between the tDMP and cDMP. Twenty additional patients with knee replacements were then selected and two observers used a cSMA to determine a femoral prosthesis flexion angle (FPFA), with intraobserver correlation calculated. ResultsThe mean DMR was found to be 0.24, with high intraobserver correlation and normal distribution. Validation of the model demonstrated angular variance between tSMA and cSMA less than 1 degree and linear distance between tDMP and cDMP less than 1 mm. Calculation of cCMA in the presence of total knee arthroplasty revealed very strong intraobserver correlation of 0.89. ConclusionThe Distal Mechanical Ratio reliably predicted the true Sagittal Mechanical Axis within 1 degree and true Distal Mechanical Point within 1 mm, indicating that it may be a valuable tool for evaluating sagittal femoral alignment in cases where anatomic landmarks may be absent or obscured.

Radio-Morphometric Analysis of Sella Turcica in Relation to Age and Gender in Sri Ganganagar Population: A Prospective Cephalometric Study.

Background Sella turcica (ST) is a crucial structure that is morphologically situated in the median position and is well-utilised in cephalometrics. This saddle-shaped sella constitutes a significant radiographic landmark for various related analyses. Therefore, studying its varying dimensions in different populations is of utmost importance. This paper evaluates and compares the linear dimensions and morphological variations of ST in different facial skeletal classes in relation to age and gender using lateral cephalograms in the Sri Ganganagar population. Methodology The study population was selected through simple random sampling from the accessible population of the Sri Ganganagar district. A total of 180 participants of both genders were selected from patients who visited the outpatient clinic of the Department of Oral Medicine and Radiology of Surendra Dental College and Research Institute in Sri Ganganagar. These samples were equally divided into three age groups. Apart from typical morphology, five possible variations of ST were determined. The area of ST on the lateral cephalogram was also evaluated. The extent of ST was calculated from the tubercle portion to the top of the dorsal side. The relative deepness of the sella was assessed by making a tangent across the innermost point of the sella.SPSS software was utilised for statistical analysis and related inferences. Results In the study sample (n = 180), 50% were men and 50% were women. The sample was divided into three equal groups based on age: Group I(n = 60; 33.33%) consisted of participants aged 15-20; Group II (n = 60; 33.33%) consisted of participants aged 21-25; and Group III (n = 60; 33.33%) consisted of participants aged 26-30. Conclusions The anteroposterior diameter of the sella structure is strongly related to age progression with no significant gender correlation. The most common shape of ST other than the normal one was oblique. Additionally, skeletal relationships showed a significant relationship with the shape of ST in the study population.

Correlations Analysis of Different Pelvic Tilt Definitions: A Preliminary Study.

Background: Pelvic tilt (PT) is described as the pelvic orientation along the transverse axis, yet 4 PT definitions were established based on radiographic landmarks: anterior pelvic plane (PTa), the center of femoral heads to sacral plate (PTm), pelvic outlet (PTh), and sacral slope (SS). These landmarks quantify a similar concept, yet understanding of their relationships is lacking, and their differences are sometimes ignored. Purpose: This study aimed to examine the correlations and differences of PT definitions for education and research purposes. Methods: This study reviewed 105 sagittal pelvic radiographs of patients (68 men and 37 women) awaiting hip surgery at a single clinic. Hip hardware and spine pathologies were examined for subgroup analysis. Two observers annotated 4 PTs in a gender-dependent manner and repeated it after 6 months. The linear regression model and intraclass correlation coefficient (ICC) were applied with a 95% confidence interval. Results: The SS showed no correlation to the other 3 PT definitions, except for females in the hip hardware subgroup (n = 17). PTm demonstrated very strong linear correlation to PTh (r > 0.9) under the linear model PTm = 0.951 × PTh - 68.284. Conclusion: The PTm and PTh can be calculated from each other under a simple linear regression equation, which enables comparisons between them. SS presented poor correlations to the other PT parameters, except for the female subgroup with hip implant that required further analysis; PTa-related comparisons showed high anatomical variations between patients.

Comparative Evaluation of The Efficiency of Panoramic Radiographs and Lateral Cephalograms in The Determination of Right and Left Gonial Angles

Introduction: Attainment of the best results post orthodontic treatment is majorly dependent on proper diagnosis and a good treatment plan. Diagnostic records lay the foundation of formulation of a good treatment plan. Among which lateral cephalograms and panoramic radiographs are important tools. Required knowledge about various parameters can be obtained by making certain linear and angular measurements. Gonial angle is one such parameter which helps an orthodontist in determining the facial pattern of an individual and thus altering the treatment plan as required. Objective: The aim of the present study was to evaluate the efficiency of lateral cephalograms and panoramic radiographs in the determination of right and left gonial angle and determination of the accuracy of both. Materials and Methods: Pre–treatment lateral cephalograms of 120 skeletal class I subjects were randomly selected and divided into 60 males and 60 females. Radiographic landmarks were located, identified and marked and various measurements were made. The measurements thus obtained were statistically analysed. Results: The mean value of gonial angle measured using the panoramic radiograph was 124.75 and that of lateral cephalogram was 125.12. No statistically significant difference was found between the gonial angle measured using lateral cephalograms and that using panoramic radiographs. Conclusion: With the present study, it can be concluded that both lateral cephalograms and panoramic radiographs effectively measure the gonial angles. However, no statistically significant difference was found in the measured angle with the two radiographs. Keywords: Panoramic Radiographs, Lateral Cephalograms, Gonial Angles

A Critical Review on the 3D Cephalometric Analysis Using Machine Learning

Machine learning applications have momentously enhanced the quality of human life. The past few decades have seen the progression and application of machine learning in diverse medical fields. With the rapid advancement in technology, machine learning has secured prominence in the prediction and classification of diseases through medical images. This technological expansion in medical imaging has enabled the automated recognition of anatomical landmarks in radiographs. In this context, it is decisive that machine learning is capable of supporting clinical decision support systems with image processing and whose scope is found in the cephalometric analysis. Though the application of machine learning has been seen in dentistry and medicine, its progression in orthodontics has grown slowly despite promising outcomes. Therefore, the present study has performed a critical review of recent studies that have focused on the application of machine learning in 3D cephalometric analysis consisting of landmark identification, decision making, and diagnosis. The study also focused on the reliability and accuracy of existing methods that have employed machine learning in 3D cephalometry. In addition, the study also contributed by outlining the integration of deep learning approaches in cephalometric analysis. Finally, the applications and challenges faced are briefly explained in the review. The final section of the study comprises a critical analysis from which the most recent scope will be comprehended.

The Schöttle Point Is Consistently Located Distal to the Medial Femoral Physis in Pediatric Patients: A Digitally Reconstructed Radiographic Study

Background: Significant controversy surrounds ideal tunnel position for medial patellofemoral ligament (MPFL) reconstruction (MPFLR) in the pediatric setting. The start point for femoral tunnel positioning (the Schöttle point) relative to the distal medial femoral physis is not well defined. Previous studies provide conflicting data regarding position of the MPFL origin and the Schöttle point relative to the distal femoral physis. Hypothesis: The Schöttle point would be consistently distal to the distal medial femoral physis. Study Design: Descriptive laboratory study. Methods: The institutional picture archiving and communication system was queried for computed tomography (CT) imaging studies of pediatric knees. Data were imported to an open-source image computing platform. True lateral digitally reconstructed radiographs and 3-dimensional (3D) renderings were generated, and the Schöttle point was registered in 3D space. Then, 3D distance measurements were obtained from the Schöttle point to the distal medial femoral physis. Results: A total of 49 pediatric knee CT scans were included. Mean age was 13.0 ± 2.3 years. Mean minimum distance from the medial physis to the Schöttle point was 9.9 ± 3.0 mm (range, 3.4-16.1 mm). In 49 of 49 cases (100%), the Schöttle point was distal to the physis. Using a 6-mm reaming diameter would result in 3 of 49 (6%) femurs having violation of the distal medial femoral physis. Moving the start point 3 mm distally would result in 0 of 49 (0%) sustaining physeal injury. Conclusion/Clinical Relevance: The Schöttle point is consistently distal to the distal medial femoral physis. The mean minimum distance from the Schöttle point to the physis on the medial cortex is 9.9 mm. The Schöttle point provides a safe and reliable radiographic landmark for pediatric MPFLR, although reaming diameter should be considered.

Fourth thoracic vertebra as landmark for depth of right internal jugular vein catheterization in infants

The carina is considered a reliable marker for the depth of right internal jugular vein catheterization in infants on chest radiograph. In adult anatomy, the carina is typically located at the level of the fifth thoracic vertebra. We are not aware of a positional relationship between infant carina and thoracic vertebrae. Thus, we evaluated that a vertebral body may be at the same level as carina and can be as radiographic landmarks for the depth of right internal jugular vein catheterization in infants. In this retrospective analysis, 108 infants (aged 1–12 months) who underwent congenital heart surgery between January 1, 2019 and June 30, 2019 were included. We analyzed the post-operative chest radiographs of those who underwent right internal jugular vein catheterization and assessed the positional relationship of the carina and vertebral bodies. We measured the vertical distance of the central venous catheter (CVC) catheter tip from the carina (below the carina 22 mm, it may be close to or into the right atrium). In total, 95 children were enrolled; The carina was located at the third thoracic vertebra in two cases (2%) and at the fourth thoracic vertebra in 93 cases (98%). The distance between the tip of CVC and the carina was 10 (4, 15) mm, and 6.3% (6 cases) had the catheter tip at more than 22 mm below the carina. Most fourth thoracic vertebrae were at the same level as the carina on chest radiographs. Therefore, it has potential as a radiographic landmark for the depth of right internal jugular vein catheterization in infants on chest radiograph.

P143. The “V” sign: a reliable anatomic and radiographic landmark for posterior percutaneous S1 screw placement

P143. The “V” sign: a reliable anatomic and radiographic landmark for posterior percutaneous S1 screw placement

The Central Sulcus of the Insula: A Highly Reliable Radiographic Landmark for Identification of the Rolandic Sulcus

Anatomic studies have suggested that the central insular sulcus (CIS) runs in line with the Rolandic sulcus (RS). The radiographic relationship between the RS and CIS has not been systematically studied. This study aims to evaluate the applicability of using the CIS as a radiologic landmark to identify the RS. We retrospectively reviewed 100 consecutive normal magnetic resonance imaging (MRI) scans (200 hemispheres) performed at a single institution. MRI scans with any intracranial pathology or finding were excluded. Sagittal and axial fluid-attenuated inversion recovery sequences were used in this study. Two evaluators independently evaluated the relationship of the CIS and RS in all MRI scans. A predefined 3-step method was then used to identify the CIS, RS, and hand motor area in sagittal and axial images. The CIS was found to be correlated with the RS in 191 hemispheres (95.5%). In the remaining 9 hemispheres, the postcentral sulcus represented the most correlated sulcus with the CIS (7 hemispheres). The interrater agreement was 0.673 (P < 0.05), indicating a substantial agreement. The hand motor area was identified in the same section as the CIS in 175 hemispheres (87.5%). The CIS is a highly reliable radiographic landmark for the identification of the RS. The hand motor area can also be identified reliably using this method.

A new understanding of radiographic landmarks of the greater trochanter that indicate correct femoral rotation for measurement of femoral offset

ObjectivesTo establish and validate a novel method for aligning femoral rotation to accurately measure femoral offset for preoperative templating and component sizing, and to identify the physical location of two radiographic lines utilized in the described method.Materials and methodsCadaveric proximal femurs were skeletonized and mounted to a biaxial load frame. Two radiographic lines along the greater trochanter were identified fluoroscopically. The femurs were rotated, and images were taken when the lines appeared superimposed, then in 2-degree increments to 10° of internal and external rotation, and at 30°. Radiographic femoral offset was calculated at each angle, and the maximum and aligned offsets were compared. Bone was removed until the radiographic lines disappeared, then a metal wire was inserted in place of the bone to confirm that the lines reappeared.ResultsThe physical locations of the radiographic landmarks were on the anterior and posterior aspects of the greater trochanter. The mean true femoral offset was 38.2 mm (range, 30.5–46.3 mm). The mean aligned femoral offset was 37.3 mm (range, 29.3–46.3 mm), a 2.4% underestimation. The mean angle between aligned and true offset was 3.6° of external rotation (range, 10°ER-8°IR). Intra-rater intraclass correlation coefficient was 0.991.ConclusionAlignment of the radiographic lines created by the anterior and posterior aspects of the greater trochanter is a reliable and accurate rotational positioning method for measuring true femoral offset when using plain films or fluoroscopy, which can aid surgeons with preoperative templating and intraoperative component placement for total hip arthroplasty.

Research Hotspots and Trends Analysis of Patellar Instability: A Bibliometric Analysis from 2001 to 2021.

BackgroundPatellar instability is a common multifactorial disease in orthopedics, which seriously affects the quality of life. Because of the unified pathogeny, diagnosis and treatment, patellar instability has gradually attracted the interest of more scholars these years, resulting in an explosive growth in the research output. This study aims to summarize the knowledge structure and development trend in the field from the perspective of bibliometrics.MethodsThe data of articles and reviews on patellar instability was extracted from the Web of Science database. The Microsoft Excel, R-bibliometrix, CiteSpace, VOSviewer, Pajek software are comprehensively used to scientifically analyze the data quantitatively and qualitatively.ResultsTotally, 2,155 papers were identified, mainly from North America, Western Europe and East Asia. Until December 31, 2021, the United States has contributed the most articles (1,828) and the highest total citations (17,931). Hospital for Special Surgery and professor Andrew A Amis are the most prolific institutions and the most influential authors respectively. Through the analysis of citations and keywords based on a large number of literatures, “medial patellofemoral ligament construction”, “tibial tubercle-trochlear groove (TT-TG) distance”, “epidemiological prevalence”, “multifactor analysis of etiology, clinical outcome and radiographic landmarks “ were identified to be the most promising research directions.ConclusionsThis is the first bibliometric study to comprehensively summarize the research trend and development of patellar instability. The result of our research provides the updated perspective for scholars to understand the key information in this field, and promote future research to a great extent.

Elongation Patterns of the Superficial Medial Collateral Ligament and the Posterior Oblique Ligament: A 3-Dimensional, Weightbearing Computed Tomography Simulation.

Background:Although length change patterns of the medial knee structures have been reported, either the weightbearing state was not considered or quantitative radiographic landmarks that allow the identification of the insertion sites were not reported.Purpose:To (1) analyze the length changes of the superficial medial collateral ligament (sMCL) and posterior oblique ligament (POL) under weightbearing conditions and (2) to identify the femoral sMCL insertion site that demonstrates the smallest length changes during knee flexion and report quantitative radiographic landmarks.Study Design:Descriptive laboratory study.Methods:The authors performed a 3-dimensional (3D) analysis of 10 healthy knees from 0° to 120° of knee flexion using weightbearing computed tomography (CT) scans. Ligament length changes of the sMCL and POL during knee flexion were analyzed using an automatic string generation algorithm. The most isometric femoral insertion of the sMCL that demonstrated the smallest length changes throughout the full range of motion (ROM) was identified. Radiographic landmarks were reported on an isometric grid defined by a true lateral view of the 3D CT model and transferred to a digitally reconstructed radiograph.Results:The sMCL demonstrated small ligament length changes, and the POL demonstrated substantial shortening during knee flexion (P = .005). Shortening of the POL started from 30° of flexion. The most isometric femoral sMCL insertion was located 0.6 ± 1.7 mm posterior and 0.8 ± 1.2 mm inferior to the center of the sMCL insertion and prevented ligament length changes >5% during knee flexion in all participants. The insertion was located 47.8% ± 2.7% from the anterior femoral cortex and 46.3% ± 1.9% from the joint line on a true lateral 3D CT view.Conclusion:The POL demonstrated substantial shortening starting from 30° of knee flexion and requires tightening near full extension to avoid overconstraint. Femoral sMCL graft placement directly posteroinferior to the center of the anatomical insertion of the sMCL demonstrated the most isometric behavior during knee flexion.Clinical Relevance:The described elongation patterns of the sMCL and POL aid in guiding surgical medial knee reconstruction and preventing graft lengthening and overconstraint of the medial compartment. Repetitive graft lengthening is associated with graft failure, and overconstraint leads to increased compartment pressure, cartilage degeneration, and restricted ROM.

Avoid the In-Out-In Posterosuperior Femoral Neck Screw: The Use of the Piriformis Fossa Radiographic Landmark.

The most common screw placement across the femoral neck is the inverted triangle. The posterosuperior screw has a high incidence of cortical breach, creating an in-out-in (IOI) screw. This study examined the use of the radiographic landmark of the piriformis fossa (PF) to prevent screws being placed IOI. The hypothesis was that posterior screws placed below the PF inferior margin would prevent femoral neck cortex breach. Five bilateral cadaveric specimens were used to place 10 screws along the femoral neck posterosuperior cortex. On the AP view, 5 screws were placed in a traditional manner, below the femoral neck superior cortex but above the inferior margin of the PF (APF screws), and 5 were placed below the inferior margin of the PF (BPF). All 10 screws were placed inside the posterior cortex on the lateral view. After screw placement, each hip was dissected, and the femoral necks were evaluated for signs of cortical breach. All screws placed below the PF inferior margin were contained within the femoral neck with no incidence of being IOI. All screws placed above the PF inferior margin breached the cortex to a varying degree. All screws were similar in relation to their distance from the posterior cortex on the lateral view, with the APF screws averaging 1.98 mm and the BPF screws averaging 1.82 mm (P value = 0.46). Placing the posterosuperior screw of the inverted triangle caudal to the PF inferior margin on the AP view seems to avoid cortical breach during percutaneous screw fixation of femoral neck fractures.