Lateral Inclination Research Articles

Use of 3D Printed Models to Determine Accurate Bone Cuts during a Periacetabular Osteotomy for Developmental Hip Dysplasia

AbstractThe periacetabular osteotomy (PAO) is a powerful tool to delay the progression of hip arthritis by reorienting the acetabulum. This study aimed to use three-dimensional (3D)-printed models of the pelvis, reconstructed from the computed tomography (CT) scans of patients, to model how the level of dysplasia and its location ilium osteotomy affect radiographic outcomes following PAO. This pilot study aims to determine if preoperative 3D printing/planning can assist in predicting radiographic outcomes. We performed a retrospective review of five patients with differing levels of hip dysplasia for whom we had obtained CT scans before PAO surgery. For each patient, we printed two pelvis models that would undergo standardized cuts of the PAO procedure, with variations only in the distance of the ilium start point (one-third of the distance between the anterior superior iliac spine and anterior inferior iliac spine [AIIS] vs. two-thirds of the distance). We then mobilized the acetabular fragment into eight reproducible positions in space by moving the ilium cut a combination of 0, 1, or 2 cm anterior/lateral. Each position of the newly realigned acetabula was examined under fluoroscopy to obtain a standardized anteroposterior view, and to obtain standardized radiographic measurements in the form of lateral center edge angle (CEA), acetabular depth, Tonnis angle, and acetabular inclination. We performed 80 simulations of the PAO with varying degrees of acetabular mobilization. On average, in the models where the supra-acetabular cut was closer to the AIIS, we found more significant degrees of radiographic correction, regarding Tonnis angles (12.91 vs. 7.95, p = 0.0175), acetabular inclination (20.25 vs. 9.875, p = 0.027), and lateral CEA (11.75 vs. 2.5, p = 0.061). Patients who had greater dysplasia also had more significant degrees of radiographic Tonnis angle correction with the same mobilization movements of the acetabula (p = 0.005). When utilizing 3D printing to model PAO in dysplasia pelvises, we found that both a higher level of preoperative dysplasia and starting the supra-acetabular osteotomy closer to the AIIS were associated with more powerful corrections following smaller manipulations.

MRI evaluation of predisposing factors in patellar instability

Objectives: In this study, we have attempted to evaluate the predisposing factors of patellar instability on magnetic resonance imaging (MRI) and to compare the significance of measurement at the level of trochlear bone versus cartilage for trochlear dysplasia. Material and Methods: Thirty patients of patellar instability were assessed on MRI for risk factors of patellar instability including trochlear dysplasia, tibial tuberosity to trochlear groove (TT-TG) distance, and patellar height ratio. Results: Twenty-one (70%) and 27 (90%) cases were positive for decreased trochlear depth when measured at the level of trochlear bone and cartilage, respectively. Eighteen (60%) and 25 (83.33%) cases were positive for trochlear facet asymmetry when measured at trochlear bone and cartilage, respectively. Twelve cases (40 %) were positive for patella alta. Ten cases (33.33%) were positive for decreased lateral trochlear inclination. Seven cases (23.3%) had increased TT to TG distance. Twenty-four cases (80%) were of age equal to or <25 years. Conclusion: According to our study, trochlear dysplasia is the most common predisposing factor of patellar instability (100%) followed by patella alta (40%) and TT-TG distance (23.3%). Trochlear depth and facet asymmetry produce better results as a predisposing factor for instability of patella when measured at the level of trochlear cartilage as compared to trochlear bone with P = 0.001.

Association of patellofemoral morphology and alignment with the radiographic severity of patellofemoral osteoarthritis

BackgroundRisk factors for the severity of patellofemoral osteoarthritis (PFOA) are poorly understood. This research aims to evaluate the association between patellofemoral joint (PFJ) morphology and alignment with the radiographic severity of PFOA.MethodsA retrospective analysis of CT scan and lateral radiograph data were acquired in patients with PFOA. The radiographic grade of PFOA and tibiofemoral osteoarthritis (TFOA), lateral and medial trochlear inclination angle, sulcus angle, and the Wiberg classification of patella morphology, the congruence angle, patellar tilt angle, and lateral patellar angles, and tibial tubercle trochlear groove distance (TT-TG) and patella height (i.e., Caton-Deschamps index) were assessed using CT scans and sagittal radiographs of the knee. All the PFJ morphology and alignment data were divided into quarters, and the relationships between each of these measures and the severity of PFOA were investigated.ResultsBy studying 150 patients with PFOA, we found a U-shaped relationship between the Caton-Deschamps index and the severity of PFOA (P < 0.001). A lower value of sulcus angle and lateral patellar angle, a higher value of congruence angle, and type III patella were associated with more severity of lateral PFOA. Compared with the highest quarter of each measure, the adjusted odds ratios (OR) of the severity of PFOA in the lowest quarter of sulcus angle, lateral patellar angle, and congruence angle; and type I patella was 8.80 (p = 0.043), 16.51 (P < 0.001), 0.04 (P < 0.001), and 0.18 (p = 0.048) respectively.ConclusionsExtreme value of patella height, a higher value of lateral patellar displacement and lateral patellar tilt, lower value of sulcus angle, and type III patella were associated with more severity of PFOA.

Using a 3D handheld scanner to capture trochlear groove shape: proof of concept study.

Trochleoplasty is a surgical procedure used to treat patellar instability by modifying the trochlear groove. Analysis of the groove with a handheld scanner would enable accurate real-time planning and facilitate tailormade correction. We aimed to measure trochlear depth, sulcus angle, trochlear facet ratio, trochlear angle and lateral trochlear inclination angle and to establish inter- and intra-rater reliability for knee models to determine reliability and repeatability. The trochlear grooves of three knee models were scanned by two investigators. Three-dimensional reference models were created and surface-matched. Custom software was used to determine the desired parameters. The intraclass correlation coefficient (ICC) was used to determine test-retest reliability and the parameter results for each model that showed best reproducibility. There was good interobserver reliability (trochlear depth, 1.0mm; sulcus angle, 2.7°; trochlear angle, 4.0°; lateral trochlear inclination angle, 4.0°), except in the trochlear facet ratio (32.0%) of one knee model. With outliers removed, the ICC was moderate to excellent in 73.34% of measurements, with trochlear depth showing the best reproducibility. This feasibility study showed a handheld scanner in conjunction with supporting software can measure trochlear parameters with good to excellent inter- and intra-observer reliability.

A cross-sectional study to assess variability in knee frontal plane movement during single leg squat in patients with anterior cruciate ligament injury

BackgroundSingle leg squat (SLS) tests help predict anterior cruciate ligament injuries. However, the variability in joint movement during this test has not been fully investigated. The aim of this study was to examine the knee frontal plane movement variability during SLS in patients with anterior cruciate ligament (ACL) injury. MethodsIn this cross-sectional study, we enrolled 56 patients with ACL injury (28 males; 28 females) and 46 healthy subjects (23 males; 23 females). All participants underwent SLS tests. All kinematic variables were joint angle of trunk, pelvis and lower limb, center of gravity (COG), center of pressure (COP). These data were obtained at the frontal plane and the coefficient of variation (CV) were calculated. Multiple comparisons were performed between healthy subjects and the injured leg and uninjured leg of patients with ACL injury. The correlation of the CV in knee varus/valgus range of motion (ROM) with the CV in other kinematic variables were investigated in patients with ACL injury. ResultsCompared with healthy subjects, patients with ACL injury exhibited significantly larger the CV in knee varus/valgus ROM. A positive correlation was observed between the CV in knee varus/valgus ROM and the CV in pelvic lateral inclination ROM in patients with ACL injury. ConclusionsKnee frontal plane movement variability during SLS may help evaluate the risk of ACL injury/re-injury. In addition, pelvic lateral inclination variability during SLS may need to be evaluated in conjunction with knee frontal plane movement variability.

THE EFFECT OF SPECIAL EXERCISES USING THE CONTINUOUS RESISTANCES OF THE LOWER EXTREMITIES AND THEIR EFFECT ON THE LATERAL INCLINATION OF THE PELVIS

From the researchers’ observation of the educational process of middle school students, it was found that there is an imbalance of power between the right and left leg, and this leads to a gradual deviation of the pelvis towards the right or left. Therefore, the researchers decided to put a rehabilitation program using light and continuous resistances to develop the balance of power in the two legs, which Returns the body to a state of force balance and prevents lateral deviation of the pelvis. The aim of the research is to identify the effect of developing the work of the lower extremities using continuous resistances and their impact on the unevenness of the length of the legs and the lateral inclination of the pelvis. The researchers assumed that there are statistically significant hypotheses between the pre and post tests in the weak leg strength represented by the variation in the length of the legs and the lateral deviation of the pelvis. The experimental method was used for one group with a pre and post test on a sample of the first intermediate grade students of (20) students Applying the introductory approach to the research sample, a set of conclusions was reached, the most important of which is that resistance exercises have a positive effect on improving some basic skills in football. The use of resistances has a positive impact on performance in general for skills.

Identifying Autism with Head Movement Features by Implementing Machine Learning Algorithms.

Our study investigated the feasibility of using head movement features to identify individuals with autism spectrum disorder (ASD). Children with ASD and typical development (TD) were required to answer ten yes-no questions, and they were encouraged to nod/shake head while doing so. The head rotation range (RR) and the amount of rotation per minute (ARPM) in the pitch (head nodding direction), yaw (head shaking direction) and roll (lateral head inclination) directions were computed, and further fed into machine learning classifiers as the input features. The maximum classification accuracy of 92.11% was achieved with the decision tree classifier with two features (i.e., RR_Pitch and ARPM_Yaw). Our study suggests that head movement dynamics contain objective biomarkers that could identify ASD.

Description of spine motion during gait in normal adolescents and young adults.

Standing radiographs allow analysis of spinal segments and their relative positioning. However, it requires a specific positioning influencing spinal alignment. Knowledge of trunk movements when walking is therefore an essential step to evaluate dynamic sagittal balance. Our objective was to define spinal junction kinematics and their correlations during gait in a healthy population. This is a prospective, single-center study. Between 2015 and 2017, 25 healthy volunteers were included. The measurements were taken in a motion analysis laboratory. Several kinematic parameters were studied, including spinal junction movements in the three planes and dynamic sagittal vertical axis (Dyn-SVA). Pearson correlation coefficients were calculated to determine the interactions between the spinal junctions. In the sagittal plane, the average amplitude of variation of the dyn-SVA was 25.5cm (SD = 8.9). The average range of motion of the lumbosacral and thoracolumbar junction was approximately 3°, they operated in anti-phase during the gait cycle and were strongly correlated (r = -0.5069, p = 0.01). In the transverse plane, the anti-rotation of the upper body relative to the pelvis was mainly ensured by the opposite movements of the lumbosacral and thoracolumbar junction (r = 0.5689, p = 0.003). In the frontal plane, the lateral inclination in the lumbar region was made in the opposite direction from the pelvis toward the carrying member. Although there is substantial inter-subject variability, our study characterized the angular movements in the three planes of the different spinal junctions, of the pelvis and the lower limbs during a gait cycle in a healthy population.

Improvement of head and neck range of motion induced by chronic pallidal deep brain stimulation for cervical dystonia.

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) has become an accepted treatment for severe cervical dystonia (CD). Assessment of therapeutic efficacy of DBS mostly focused on head position at rest but hardly on limitations of head and neck mobility, which represent a functionally important impairment in CD. We aimed to determine prospectively head and neck range of motion (ROM) preoperatively and during chronic bilateral GPi DBS in a series of 11 patients with idiopathic CD or segmental dystonia with prominent CD using a computerized motion analysis. Maximum horizontal rotation of the head in the transverse plane and lateral inclination in the frontal plane were measured preoperatively and at a median of 7months of chronic GPi DBS, using an ultrasound-based three-dimensional measuring system combined with surface electromyography of cervical muscles. Horizontal rotation of the head increased from 78.8° ± 31.5° (mean ± SD) preoperatively to 100.7° ± 24.7° with GPi DBS (p < 0.01), thereby improvement of head rotation to the anti-dystonic side (+ 14,2° ± 12,2°) was greater than to the pro-dystonic side (+ 7,8° ± 9,2°; p < 0.05). Movement-related agonistic-antagonistic EMG modulation during head rotation was enhanced with GPi DBS in both sternocleidomastoid (modulation index (MI) 35.8% ± 26.7% preoperatively vs. 67.3% ± 16.9% with GPi DBS, p < 0.01), and splenius capitis muscles (MI 1.9% ± 24.5% preoperatively vs. 44.8% ± 11.6% with GPi DBS, p < 0.01). Chronic bilateral GPi DBS significantly improves head ROM in CD, likely due to enhanced agonist-antagonist EMG activity with reduced co-contraction. Computerized motion analysis provides an objective measurement to assess the improvement of head and neck mobility in CD.

MPFL Length Change Patterns in Asymptomatic Knees of Patients with Contralateral Patellar Instability

Objectives:Recreating the isometry of the medial patellofemoral ligament (MPFL) is critical during patellar stabilization surgery to restore patellar kinematics. The native MPFL is reported to remain constant in length from 0-70°knee flexion in normal knees. However, patients with patellar instability have morphologic abnormalities that may alter the isometric function of the ligament. Length change patterns of the intact MPFL in such patients have not been described.Methods:3D digital knee models were created from dynamic CT images of 10 patients with unilateral patellar instability who were confirmed to have no symptoms on the contralateral knee. At each flexion angle, MPFL length was calculated based on the distance between its known attachment points. Straight line representation of the MPFL was allowed to wrap around the femoral condyle to ensure accurate length measurement. Morphologic characteristics of each knee were recorded, including sulcus angle and lateral trochlear inclination (LTI) as measurements of trochlear dysplasia, trochlear alpha angle to measure trochlear length, tibial tuberosity to trochlear groove (TTTG) distance to measure malalignment, and Caton Deschamps Index (CDI) to measure patellar height. Changes in MPFL length were assessed relative to knee flexion angle in each patient and correlated with morphologic characteristics.Results:10 knees were included in this study, with a mean age of 20.4+/-4.7 yrs. Mean sulcus angle was 153.4+/-8.9°, LTI 14.1+/-4.0°, trochlear alpha angle 66.1+/-5.8°, TTTG distance 18.3+/-3.1mm, CDI 1.1+/-0.1. Mean MPFL length varied from 62.5+/-4.9mm at 50° knee flexion to 74.4+/-3.9mm at 0°, with a 20.1+/-8.8% change in length (p<0.001). No significant length changes were noted between 30° and 50° flexion. Moderate correlation was noted between increasing MPFL length change and measurements of trochlear length (R=-0.55, p=0.017).Conclusions:In the asymptomatic knees of patients with contralateral patellar instability, the calculated MPFL length based on known anatomic attachment points varied by 20.1%, or an average of 12.1mm, between 50° flexion and full extension. This suggests that the isometric function of the intact MPFL in these patients may not reflect previously described findings in anatomically normal patients. Further studies are needed to understand the pathoanatomy related to these changes, as well as the implications for graft placement and assessment of isometry in MPFL reconstruction techniques.

Investigation of the relationship between trochlear morphology and medial patellar cartilage defect using magnetic resonance imaging

The aim of this study was to evaluate trochlear morphology in patients with medial patellar cartilage defects via magnetic resonance imaging (MRI). Three hundred patients who were diagnosed with grade 2, 3 and 4 medial patellar cartilage defect using MRI according to the International Cartilage Repair Society Classification System and 100 control subjects were evaluated. Trochlear morphology was evaluated based on lateral trochlear inclination (LTI), medial trochlear inclination (MTI), sulcus angle( SA), femoral lateral and medial condyle symmetry, trochlear facet asymmetry, and trochlear width on the axial MR images. The mean SA was significantly higher in the medial patellar cartilage defect group compared to the control group (p<.05). The LTI and MTI of the cartilage defect group were significantly lower than those of the control group (p<.05). With the decreasing LTI and MTI, there was an increase in medial patellar cartilage loss. LTI (r=-0.46) and MTI (r=-0.53) were moderately correlated with SA. There was no significant differences in femoral lateral and medial condyle symmetry, trochlear facet asymmetry, and trochlear width between groups with and without medial patellar cartilge defect (p ˃ .05). A flattened medial trochlea is a risk factor for cartilage structural damage of the medial patellofemoral joint, and it plays a role in the development of a defect in the medial patellar cartilage. The medial patellar cartilage defect is associated with the flattened lateral trochlea.

Role of Magnetic Resonance Imaging in Study of the Patellofemoral Joint Morphological Abnormalities Predisposing to Patellar Instability

Objectives: The Patellofemoral joint (PFJ) is a complex joint structure with high functional and biomechanical requirements. The purpose of this study is to evaluate cause of patella-femoral joint instability with in-depth evaluation of influence of anatomical risk factors (AF), measurements and anatomical relationships of the patellofemoral joint and various pathologies causing medial patellofemoral ligament (MPFL) injury that contributes to the patellar maltracking using 1.5 Tesla magnetic resonance imaging. Materials and Methods: The present prospective study is carried out at department of radiology, shri M P Shah Medical College, Jamnagar. This is study of total 50 patients carried out in 12-month duration from July 2019 to June 2020, in which 50 patients aged between 8 - 68 years selected as study group presented with complaint symptoms of patellofemoral instability, knee pain and maltracking were examined and identified by an orthopaedic surgeon. Patients with the clinical suspicion of a PFJ maltracking were selected for subsequent MRI examination. Results: The age distribution in our study was in range of 8 years to 68 years with maximum population within 31 to 40 years range, 66 % were male and 34 % female. Their trochlear depth, sulcal angle, trochlear facet asymmetry, lateral inclination angle was found abnormal in 18 cases (36%), 8 (16%) showed patellar alta and 7 (14%) patella baja. Lateralization of patella (&gt; 6 mm) was noted in 18 patients (36%), Medial patellofemoral ligament injuries were seen in 16 (32%) patients on MRI and kissing contusion 10 (20%) patients. A detailed understanding of the anatomy and pathology of the anterior knee compartment is essential for proper imaging interpretation and treatment management. Conclusion: Magnetic resonance (MR) imaging has been established as the method of choice, showing high accuracy in patellofemoral joint abnormalities. The present study aims to explore the role of MR imaging in diagnosing the various disorders located in anterior compartment of knee. Keywords: Joint instability, Patellofemoral joint, MPFL, MR imaging/diagnosis.

CT-scan based anatomical study as a guidance for infra-acetabular screw placement

BackgroundThe infra-acetabular corridor is quite narrow, which makes a challenge for the orthopedists to insert the screw. This study aimed to explore the relationship between the infra-acetabular corridor diameter (IACD) and the minimum thickness of medial acetabular wall (MTMAW), and to clarify the way of screw placement.MethodsThe Computed tomography (CT) data of 100 normal adult pelvises (50 males and 50 females respectively) were collected and pelvis three-dimensional (3D) reconstruction was performed by using Mimics software and the 3D model was imported into Geomagic Studio software. The perspective of acetabulum was carried out orienting from iliopubic eminence to ischial tuberosity and the IACD was measured by placing virtual screws which was vertical to the corridor transverse section of “teardrop”. The relationship between IACD and MTMAW was analyzed. When IACD was ≥5 mm, 3.5 mm all-in screws were placed. When IACD was < 5 mm, 3.5 mm in-out-in screws were placed.ResultsThe IACD of males and females were (6.15 ± 1.24) mm and (5.42 ± 1.01) mm and the MTMAW in males and females were (4.40 ± 1.23) mm and (3.60 ± 0.81) mm respectively. The IACD and MTMAW in males were significantly wider than those of females (P < 0.05), and IACD was positively correlated with MTMAW (r = 0.859), the regression equation was IACD = 2.111 + 0.917 MTMAW. In the all-in screw group, 38 cases (76%) were males and 33 cases (66%) were females respectively. The entry point was located at posteromedial of the apex of iliopubic eminence, and the posterior distance and medial distance were (8.03 ± 2.01) mm and (8.49 ± 2.68) mm respectively in males. As for females, those were (8.68 ± 2.35) mm and (8.87 ± 2.79) mm respectively. In the in-out-in screw group, 12 cases (24%) were males and 17 cases (34%) were females, respectively. The posterior distance and medial distance between the entry point and the apex of iliopubic eminence were (10.49 ± 2.58) mm and (6.17 ± 1.84) mm respectively in males. As for females, those were (10.10 ± 2.63) mm and (6.63 ± 1.49) mm respectively. The angle between the infra-acetabular screw and the sagittal plane was medial inclination (0.42 ± 6.49) °in males, lateral inclination (8.09 ± 6.33) °in females, and the angle between the infra-acetabular screw and the coronal plane was posterior inclination (54.06 ± 7.37) °.ConclusionsThe placement mode of the infra-acetabular screw (IAS) can be determined preoperatively by measuring the MTMAW in the CT axial layers. Compared with all-in screw, the in-out-in screw entry point was around 2 mm outwards and backwards, and closer to true pelvic rim.

Usefulness of three-dimensional computed tomography for patellofemoral measurement.

This study aimed to establish the normal values for knee patellofemoral alignment as measured using 3-dimensional computed tomography (3D CT), to standardize the technique, and to show the inter- and intra-observer reliability of this measurement. The present study included 62 asymptomatic volunteers (124 knees). 3D CT scanning was performed with each volunteer in the supine position with 15° of knee flexion, and consistent 3D axial images of the patellofemoral joint were obtained with alignment in the desired stereographic baseline direction in anterior-posterior, lateral, and axial rotations. Two independent observers measured patellofemoral alignment parameters, including the sulcus angle, congruence angle, lateral patellofemoral angle, condyle-patellar angle, and lateral trochlear inclination angle. Based on 3D CT measurement, the mean values of the parameters were 145.9° ± 9.2° for the sulcus angle, 12.6° ± 22.6° for the congruence angle, 9.2° ± 4.6° for the lateral patellofemoral angle, 14.1° ± 6.4° for the condyle-patellar (lateral facets) angle, -8.5° ± 8.4° for condyle-patellar (patellar axis) angle, and 16.5° ± 6.3° for the lateral trochlear inclination angle. A statistically significant difference was observed between men and women in the sulcus and condyle-patellar (patellar axis) angles (p = 0.045, 0.011, respectively). All parameters showed excellent inter- and intra-observer reliability. The normal values and ranges for patellofemoral alignment parameters were evaluated using 3D CT. The results of this study provide reference information that may facilitate diagnosis and treatment planning of patellofemoral disorders in skeletally mature non-pathologic patients. II.

Outcomes After Deepening Trochleoplasty and Concomitant Realignment in Patients With Severe Trochlear Dysplasia With Chronic Patellofemoral Pain: Results at 2-Year Follow-up.

Background:Abnormal patellofemoral joint stress appears to have major relevance in a subgroup of patients with patellofemoral pain (PFP).Purpose:To evaluate whether patients with chronic PFP and trochlear dysplasia–induced patellofemoral joint malalignment benefit from a deepening trochleoplasty procedure with the aim of improving patellotrochlear congruence.Study Design:Case series; Level of evidence, 4.Methods:Included were 15 patients (male/female, 1/14; mean age, 30.3 years [range, 19-51 years]) with 8.8 years (range, 1-20 years) of chronic PFP and severe trochlear dysplasia. All patients underwent correction of patellotrochlear malalignment with deepening trochleoplasty and concomitant realignment procedures. The Kujala score and a numerical analog scale (0-10) for intensity of pain were used to assess symptoms preoperatively and at 12 and 24 months postoperatively. Pre- and postoperative magnetic resonance imaging (MRI) scans from the patients were compared with the MRI scans of age- and sex-matched controls regarding the patellotrochlear contact area and contact ratio, patellar tilt, patellotrochlear index, and lateral trochlear inclination (LTI) angle.Results:The Kujala score increased from a mean of 55 (range, 15-81) preoperatively to 82.5 (range, 53-98) after 12 months (95% CI, –42.56 to –12.37; P < .001) and to 84.2 (range, 59-99) after 24 months (95% CI, –44.29 to –14.11; P < .001). The intensity of PFP decreased from 5.7 (range, 3-10) preoperatively to 1.4 (range, 0-4) after 12 months (95% CI, 2.57 to 5.96; P < .001) and had a mean of 1.6 (range, 0-6) after 24 months (95% CI, 2.44 to 5.75; P < .001). Preoperatively, parameters in the study group indicated significant patellotrochlear malalignment, which improved and normalized (except for the LTI angle) postoperatively compared with the values of the control group (P > .05).Conclusion:In a subgroup of patients with chronic PFP due to severe trochlear dysplasia, deepening trochleoplasty and concomitant realignment procedures significantly reduced pain and improved knee joint function while normalizing patellotrochlear congruence.

Structural changes caused by dips in lateral ramps of fold and thrust belts

Transverse zones are tectonic structures parallel or oblique to the shortening direction. Lateral ramps are inherited tectonic structures and are comprised in a transverse zone. During shortening transverse zones are usually confused with simple strike-slip faults. We evaluated 36 analogue models under brittle conditions using two frontal ramps connected by a lateral ramp at different inclinations (30°, 45°, and 60°) to identify lateral ramps characteristics in the fold and thrust belts. The experiments were conducted in a subduction-type sandbox, using dry sand and a rigid block, representing a brittle crust and the backstop. During shortening, faults and folds related grow parallel to frontal ramps. Significative plunges correlate with the inclination of the lateral ramp. The oblique faults dipped along the direction opposite to the lateral ramp, while the normal faults parallel to the lateral ramp only occurred when linked to lateral ramps with high inclinations. The inclination of the lateral ramp controls the plunge and rotation of the folds and thrust structures. Regardless of the lateral ramp inclinations, in map view, the main characteristics used to identify lateral ramps are i) disrupted structures along the strike in the lateral ramp area and ii) oblique faults related to frontal ramp structures.

Morphological Analysis of Bone Deformities of the Distal Femur in Toy Poodles with Medial Patellar Luxation.

The aim of this study was to evaluate the bone deformities of the distal femur of Toy Poodles with medial patellar luxation (MPL) using computed tomography. Computed tomography data from 37 stifles of Toy Poodles (16 normal, 10 grade 2 MPL and 11 grade 4 MPL) were analysed. For trochlear morphology, sulcus angle, medial or lateral trochlear inclination and trochlear angle were compared. For condylar morphology, distance between the apex of the medial or lateral trochlear ridge and the most caudal point of the medial or lateral femoral condyle (MC or LC), the length of the cranial/middle (anterior) part (MC(a) or LC(a')) and caudal (posterior) part (MC(p) or LC(p')) of distal femur and medial or lateral condyle width (MCW or LCW) were measured, and the ratios of medial-to-lateral condyles and anterior-posterior parts were compared. Sulcus angle was significantly higher, and medial trochlear inclination was significantly lower in grade 4 MPL group than other groups. Lateral trochlear inclination was not significantly different among 3 groups. Trochlear angles at proximal trochlear groove were significantly lower in grade 4 MPL group than other groups. MC/LC, MC(a)/LC(a'), MC(a)/MC(p), and LC(a')/LC(p') were significantly lower in grade 4 MPL group than other groups; however, there were no significant differences in MC(p)/LC(p') and MCW/LCW among three groups. Hypoplasia of the cranial and middle rather than caudal compartment of the distal femur was the primary morphological abnormality in Toy Poodles with grade 4 MPL.

Trochlear Dysplasia as Shown by Increased Sulcus Angle Is Associated With Osteochondral Damage in Patients With Patellar Instability

The primary study objective was to describe the incidence of osteochondral damage (OD) in our cohort of patients with patellar instability (PI). The secondary objective was to assess for associations between patient demographic characteristics, duration of PI, and quantitative radiographic measurements of anatomic risk factors for PI and OD in this cohort. A retrospective chart review identified patients treated for PI at a tertiary referral center between 2013 and 2018. Patients were evaluated for osteochondral injury with either magnetic resonance imaging if treated nonoperatively or operative reports if treated surgically. The Caton-Deschamps ratio, proximal tibial tubercle-to-trochlear groove (pTT-TG) distance, distal tibial tubercle-to-trochlear groove (dTT-TG) distance, lateral trochlear inclination (LTI) angle, lateral patellar inclination (LPI) angle, and sulcus angle were calculated from magnetic resonance imaging scans. Trochlear dysplasia is an important risk factor for PI that can be reliability quantified by the pTT-TG distance, dTT-TG distance, LTI angle, sulcus angle, and LPI angle. Demographic data including age at first instability event, sex, body mass index, symptom duration, and number of dislocations were documented. A total of 125 knees in 118 patients (average age, 13.9 ± 3.4 years; 48% female patients) with PI were identified. Within this cohort, 67% were treated surgically and 53% had OD. No association was identified between osteochondral injury and age, sex, body mass index, symptom duration, LTI angle, LPI angle, dTT-TG distance, pTT-TG distance, or number of dislocations. An increased sulcus angle (more dysplasia) showed a statistically significant association with osteochondral pathology (P= .021), and higher sulcus angles were statistically significantly associated with acute osteochondral fracture compared with chondral injury (P= .001). Using quantitative analysis of trochlear dysplasia, this study identified a significant associationbetween trochlear dysplasia (sulcus angle) and the incidence of OD in our cohort of patients with PI. The frequency of dislocation or subluxation and patient demographic characteristics were not significantly associated with OD. Level III, retrospective prognostic study.

199 Use of A 3D Hand-Held Scanner to Capture Trochlear Groove Shape, A Proof-of-Concept Study

Abstract Introduction Trochleoplasty is a surgical procedure used to treat patellar instability through modifying the trochlear groove. Analysis of the groove with a hand-held scanner would enable accurate real time planning and facilitate tailor made correction. We aimed to measure trochlear depth, sulcus angle, trochlear facet ratio, trochlear angle and lateral trochlear inclination angle and establish inter- and intra-rater reliability for each knee model. Method The trochlear groove of the knee models was scanned by two investigators and 3D reference models created. These were surface matched and custom software along with Excel was utilised to determine the desired parameters. Intraclass correlation coefficient (ICC) was used for test-retest reliability and to determine which parameter results, for each model, showed the best reproducibility. Results There was good inter-observer reliability - trochlear depth (1.0 mm), sulcus angle (2.7°), trochlear angle (4.0°) and lateral trochlear inclination angle (4.0°), except in the trochlear facet ratio (32.0%) of one knee model. With outliers removed ICC was good-excellent in (46.7%) of measurements, with trochlear depth showing the best reproducibility. Conclusions This feasibility study showed that the hand-held scanner in conjunction with supporting software can measure trochlear parameters in a controlled environment and justifies extending research into its use in trochleoplasty.

The position of the head during treatment in the emergency room-an explorative analysis of immobilization of the cervical spine

Immobilization of the cervical spine is astandard procedure in emergency medicine mostly achieved via a cervical collar. In the emergency room other forms of immobilization are utilized as cervical collars have certain drawbacks. The present study aimed to provide preliminary data on the efficiency of immobilization in the emergency room by analyzing the residual spinal motion of the patient's head on different kinds of head rests. In the present study biomechanical motion data of the cervical spine of atest subject were analyzed. The test subject was placed in asupine position on amobile stretcher (Stryker M1 Roll-In System, Kalamazoo, MI, USA) wearing acervical collar (Perfit ACE, Ballerup, Denmark). Three different head rests were tested: standard pillow, concave pillow and cavity pillow. The test subject carried out apredetermined motion protocol: right side inclination, left side inclination, flexion and extension. The residual spinal motion was recorded with wireless motion trackers (inertial measurement unit, Xsens Technologies, Enschede, The Netherlands). The first measurement was performed without a cervical collar or positioning on the pillows to measure the physiological baseline motion. Subsequently, three measurements were taken with the cervical collar applied and the pillows in place. From these measurements, amotion score was calculated that can represent the motion of the cervical spine. When the test subject's head was positioned on astandard pillow the physiological motion score was reduced from 69 to 40. When the test subject's head was placed on concave pillow the motion score was further reduced from 69 to 35. When the test subject's head was placed on cavity pillow the motion score was reduced from 69 to 59. The observed differences in the overall motion score of the cervical spine are mainly due to reduced flexion and extension rather than rotation or lateral inclination. The motion score of the cervical spine using motion sensors can provide important information for future analyses. The results of the present study suggest that trauma patients can be immobilized in the early trauma phase with acervical collar and ahead rest. The application of acervical collar and the positioning on the concave pillow may achieve agood immobilization of the cervical spine in trauma patients in the early trauma phase.