Acetabular Surface Research Articles

The bone trauma and soft-tissue injury classification system in total hip arthroplasty (BOSTI Hip).

The primary objective of this study was to develop a validated classification system for assessing iatrogenic bone trauma and soft-tissue injury during total hip arthroplasty (THA). The secondary objective was to compare macroscopic bone trauma and soft-tissues injury in conventional THA (CO THA) versus robotic arm-assisted THA (RO THA) using this classification system. This study included 30 CO THAs versus 30 RO THAs performed by a single surgeon. Intraoperative photographs of the osseous acetabulum and periacetabular soft-tissues were obtained prior to implantation of the acetabular component, which were used to develop the proposed classification system. Interobserver and intraobserver variabilities of the proposed classification system were assessed. The BOne trauma and Soft-Tissue Injury classification system in total Hip arthroplasty (BOSTI Hip) grades osseous acetabular trauma and periarticular muscle damage during THA. The classification system has an interclass correlation coefficient of 0.90 (95% CI 0.86 to 0.93) for interobserver agreement and 0.89 (95% CI 0.84 to 0.93) for intraobserver agreement. RO THA was associated with improved BOSTI Hip scores (p = 0.002) and more pristine osseous surfaces in the anterior superior (p = 0.001) and posterior superior (p < 0.001) acetabular quadrants compared with CO THA. There were no differences between the groups in relation to injury to the gluteus medius (p = 0.084), obturator internus (p = 0.241), piriformis (p = 0.081), superior gamellus (p = 0.116), inferior gamellus (p = 0.132), quadratus femoris (p = 0.208), and vastus lateralis (p = 0.135), but overall combined muscle injury was reduced in RO THA compared with CO THA (p = 0.023). The proposed BOSTI Hip classification provides a reproducible grading system for stratifying iatrogenic bone trauma and soft-tissue injury during THA. RO THA was associated with improved BOSTI Hip scores, more pristine osseous acetabular surfaces, and reduced combined periarticular muscle injury compared with CO THA. Further research is required to understand if these intraoperative findings translate to differences in clinical outcomes between the treatment groups.

Methods for three-dimensional characterization of the acetabulum prior to pelvic reorientation osteotomy: a scoping review.

Periacetabular osteotomy is the gold standard treatment for acetabular dysplasia. The great variability of acetabular dysplasia requires a personalized preoperative planning improved by 3D reconstruction and computer-assisted surgery. To plan the displacement of the acetabular fragment by a pelvic osteotomy, it is necessary to define a reference plane and a method to characterize 3D acetabular orientation. A scoping review was performed on PubMed to search for articles with a method to characterize the acetabulum of native hips in a 3D reference frame. Ninety-eight articles out of 3815 reports were included. Three reproducible reference planes were identified: the anterior pelvic plane, the Standardization and Terminology Committee plane used in gait analysis, and the sacral base plane. The different methods for 3D analysis of the acetabulum were divided in four groups: global orientation, triplanar measurements, segmentation, and surface coverage of the femoral head. Two methods were found appropriate for reorientation osteotomies: the global orientation by a vector method and the triplanar method. The global orientation method relies on the creation of a vector from the acetabular rim, from the acetabular surface or from successive planes. Normalization of the global acetabular vector would correct acetabular dysplasia by a single alignment maneuver on an ideal vector. The triplanar method, based on angle measurements at the center of the femoral head, would involve correction of anomalies by considering axial, frontal, and sagittal planes. Although not directly fit for reorientation, the two others would help to candidate patients and verify both planning and postoperative result.

3.0T magnetic resonance imaging-based hip bone models for femoroacetabular impingement syndrome are equivalent to computed tomography-based models.

This study aimed to compare three-dimensional (3D) proximal femoral and acetabular surface models generated from 3.0T magnetic resonance imaging (MRI) to the clinical gold standard of computed tomography (CT). Ten intact fresh-frozen cadaveric hips underwent CT and 3.0T MRI scans. The CT- and MRI-based segmented models were superimposed using a validated 3D-3D registration volume-merge method to compare them. The least surface-to-surface distance between the models was calculated by a point-to-surface calculation algorithm using a custom-written program. The variables of interest were the signed and absolute surface-to-surface distance between the paired bone models. One-sample t-tests were performed using a signed and absolute test value of 0.16 mm and 0.37 mm, respectively, based on a previous study that validated 1.5T MRI bone models by comparison with CT bone models. For the femur, the average signed and absolute surface-to-surface distance was 0.18 ± 0.09 mm and 0.30 ± 0.06 mm, respectively. There was no difference in the signed surface-to-surface distance and the 0.16 mm test value (t = 0.650, p = 0.532). However, the absolute surface-to-surface difference was less than the 0.37 mm test value (t = -4.025, p = 0.003). For the acetabulum, the average signed and absolute surface-to-surface distance was -0.06 ± 0.06 mm and 0.26 ± 0.04 mm, respectively. The signed (t = -12.569, p < 0.001) and absolute (t = -8.688, p < 0.001) surface-to-surface difference were less than the 0.16 mm and 0.37 mm test values, respectively. Our data shows that 3.0T MRI bone models are more similar to CT bone models than previously validated 1.5T MRI bone models. This is likely due to the higher resolution of the 3T data.

Locating an iliac cortical window for reduction of an acetabular dome impaction: A computed tomography and cadaveric study

This study aimed to determine the optimal location of the iliac cortical window (ICW) for the direct reduction of acetabular dome impactions using a reference bony landmark. MethodsIn the first part of the study, computed tomography scans of 10 normal acetabula, the femoral head weight bearing area, were projected through the superior iliac cortical surface perpendicular to the plane of the true pelvis to show the area that corresponds to the acetabular dome. A line connecting each pair of anterior inferior iliac spines (AIIS) was drawn then reflected in the superior surface of the acetabulum and a reference point (RP) was marked on the line halfway between the AIIS and the pelvic brim. A 12-point 1-cm interval grid with horizontal and vertical axes labeled A, B, C and 1 to 4, respectively, overlying the acetabular surface projection was created to identify the location of the acetabular dome. In the second part of the study, the 12-point grid was marked on eight fresh cadavers (16 acetabula) and the same acetabular dome reference point was identified. K-wires were drilled into the acetabula using a parallel drill guide at each of the twelve grid points. An arthrotomy was carried out and the locations of the K-wires which penetrated the acetabular dome were recorded. ResultsThe average distance from the AIIS to the medial pelvic brim in the CT scans and cadaveric study were 47.7 and 45.9 mm, respectively. The K-wires at grid points B2 and C1 had a 100% correlation to the dome area. The A2, B1, and C2 grid points had a correlation with the dome area of >80%. The remaining grid points had joint penetrations ranging from 6.25% to 62.5%. ConclusionThe proposed RP, which can be easily identified intraoperatively, and the area 1 cm2 around the RP (except in the posterior direction) can be used as reliable reference landmarks and for identification of the location of the ICW for the reduction of an acetabular dome impaction.

On the estimation of hip joint centre location with incomplete bone ossification for foetus-specific neuromusculoskeletal modeling

Childbirth is a complex physiological process in which a foetal neuromusculoskeletal model is of great importance to develop realistic delivery simulations and associated complication analyses. However, the estimation of hip joint centre (HJC) in foetuses remains a challenging issue. Thus, this paper aims to propose and evaluate a new approach to locate the HJC in foetuses. Hip CT-scans from 25 children (F = 11, age = 5.5 ± 2.6 years, height = 117 ± 21 cm, mass = 26 kg ± 9.5 kg) were used to propose and evaluate the novel acetabulum sphere fitting process to locate the HJC. This new approach using the acetabulum surface was applied to a population of 57 post-mortem foetal CT scans to locate the HJC as well as to determine associated regression equations using multiple linear regression. As results, the average distance between the HJC located using acetabulum sphere fitting and femoral head sphere fitting in children was 1.5 ± 0.7 mm. The average prediction error using our developed foetal HJC regression equations was 3.0 ± 1.5 mm, even though the equation for the x coordinate had a poor value of R2 (R2 for the x coordinate = 0.488). The present study suggests that the use of the acetabulum sphere fitting approach is a valid and accurate method to locate the HJC in children, and then can be extrapolated to get an estimation of the HJC in foetuses with incomplete bone ossification. Therefore, the present paper can be used as a guideline for foetus specific neuromusculoskeletal modelling.

Arthroscopic assistance during open reduction and fixation for complex acetabular fractures.

Achieving an anatomical reduction in acetabular fracture is essential but may also be challenging. Most of complex fractures are treated with anterior approaches without direct visualization of the acetabular surface. In this paper, we present the surgical technique for arthroscopic assistance during open reduction and fixation for complex acetabular fractures. To our knowledge, this technique has not been described in the literature yet.

Paper 65: Novel CT-Derived 3D Modeling Assessing Dysplastic Hips Versus Controls Demonstrates Decreased 2D Lateral Center Edge Angle, but not Tönnis Angle, Predicts Decreased 3D Anterolateral Coverage

Paper 65: Novel CT-Derived 3D Modeling Assessing Dysplastic Hips Versus Controls Demonstrates Decreased 2D Lateral Center Edge Angle, but not Tönnis Angle, Predicts Decreased 3D Anterolateral Coverage

Medium-term clinical results in patients with floating hip injuries

BackgroundThe objective of this study was to evaluate the effectiveness of our strategy for managing floating hip injuries.MethodsFrom January 2014 and December 2019, all patients with a floating hip underwent surgical treatment in our hospital were included in the retrospective study, with a minimum follow-up of 1 year. All patients were managed according to a standardised strategy. Data on epidemiology, radiography, clinical outcomes and complications were collected and analysed.ResultsTwenty-eight patients were enrolled, with an average age of 45 years. The mean follow-up was 36.9 months. According to the Liebergall classification, Type A floating hip injuries predominated (n = 15, 53.6%). Head and chest injuries were the most common associated injuries. When multiple operative settings were required, we prioritized the fixation of the femur fracture at the first operation. The mean time from injury to definitive femoral surgery was 6.1 days, with most (75%) femoral fractures treated with intramedullary fixation. More than half (54%) of acetabular fractures were treated with a single surgical approach. Pelvic ring fixation included isolated anterior fixation, isolated posterior fixation, combined anterior and posterior fixation, of which isolated anterior fixation was the most common. Postoperative radiographs suggested that the anatomic reduction rates of acetabulum and pelvic ring fractures were 54% and 70%, respectively. According to grading system of Merle d’Aubigne and Postel, 62% of patients achieved satisfactory hip function. Complications included delayed incision healing (7.1%), deep vein thrombosis (10.7%), heterotopic ossification (10.7%), femoral head avascular necrosis (7.1%), post-traumatic osteoarthritis (14.3%), fracture malunion (n = 2, 7.1%) and nonunion (n = 2, 7.1%). In the patients with complications described above, only two patients underwent resurgery.ConclusionsAlthough there is no difference in clinical outcomes and complications among different types of floating hip injuries, special attention should be paid to anatomical reduction of the acetabular surface and restoration of the pelvic ring. In addition, the severity of such compound injuries often exceeds that of an isolated injury and often requires specialised multidisciplinary management. Because of no standard guidelines for treatment of such injuries, our experience in the management of such a complex case is to fully assess the complexity of the injury and formulate an appropriate surgical plan based on the principles of damage control orthopaedics.

Statistical Shape Modelling the In Vivo Location of Acetabular Wear in Retrieved Hip Implants.

Edge-wear in acetabular cups is known to be correlated with greater volumes of material loss; the location of this wear pattern in vivo is less understood. Statistical shape modelling (SSM) may provide further insight into this. This study aimed to identify the most common locations of wear in vivo, by combining CT imaging, retrieval analysis and SMM. Shape variance was described in 20 retrieved metal-on-metal acetabular surfaces. These were revised after a mean of 90 months, from 13 female and seven male patients. They were positioned with a mean inclination and anteversion of 53° and 30°, respectively. Their orientation, in vivo, was established using their stabilising fins, visible in pre-revision CT imaging. The impact of wear volume, positioning, time, gender and size on the in vivo location of wear was investigated. These surfaces had a mean wear volume of 49.63 mm3. The mean acetabular surface displayed superior edge-wear centred 7° within the posterosuperior quadrant, while more of the volumetric wear occurred in the anterosuperior quadrant. Components with higher inclination had greater superior edge-wear scars, while a relationship was observed between greater anteversion angles and more posterosuperior edge-wear. This SSM method can further our understanding of hip implant function, informing future design and may help to refine the safe zone for implant positioning.

First occurrence of a frog-like batrachian (Amphibia) in the Late Triassic Fleming Fjord Group, central East Greenland

During the Triassic, Batrachia diverged into ancestors of frogs (Salientia) and salamanders (Caudata). Fossils of Triassic batrachians are rare and found only in a few outcrops, such as the Middle Sakamena Formation of Madagascar (Induan). Only three Triassic taxa have been described, the two early frogs Triadobatrachus and Czatkiobatrachus and the early salamander Triassurus. Here we describe a right ilium, collected in 1991, attributed to the first batrachian from the Late Triassic Carlsberg Fjord Member (Ørsted Dal Formation, Fleming Fjord Group) in the Jameson Land Basin, located in central East Greenland. The fossil specimen only displays the proximal part of a right ilium, missing its shaft. After a thorough comparison with several clades (lizards, temnospondyls, salamanders and frogs), we consider the specimen as a lissamphibian sharing feature with salientians and anurans: squarish acetabular region, deeply concave acetabular surface, laterally projecting acetabular rim, flat mesial surface. It is the youngest Triassic specimen of Batrachia to date and one of the northernmost of the Late Triassic.

Investigation of Surface Roughness in Novel Magnetorheological Finishing of the Internal Hemispherical-Shaped Acetabular Cup Workpieces

Abstract In today’s world, the hemispherical-shaped component’s fine finishing with high wear resistance and dimensional accuracy is required in different applications such as shells, molds, and implants. The magnetorheological finishing (MRF) method using a novel hemispherical tip-based tool is used to finish the hemispherical cups. The study aims to develop a novel theoretical mathematical model to predict the surface roughness reduction of the hemispherical cups using the present MRF process. Because the magnetic field regulates forces in the MRF process, the effect of the magnetic flux density (MFD) in the fine finishing of the hemispherical acetabular cup workpiece has been examined theoretically and experimentally. The mathematical model for reducing surface roughness is next tested experimentally on a hemispherical acetabular cup workpiece surface. The results of the predicted roughness match well with the experimental values with the error ranging from 1.17% to 6.15%. Further, surface morphology, microhardness, and dimensional accuracy tests are done on the workpiece using scanning electron microscopy, a microhardness tester, and coordinate measuring equipment to evaluate the efficacy of the present process. The present mathematical model for the MRF process predicts fine finishing along with the overall enhancement in the surface quality of the hemispherical acetabular cup surface.

Surface Finish of Total Hip Arthroplasty Implants: Are We Evaluating and Manufacturing Them Appropriately?

Abstract A recent change in the ISO 7206-2, Implants for Surgery – Partial and Total Hip Joint Prostheses – Part 2: Articulating Surfaces Made of Metallic, Ceramic and Plastics Materials, with regard to hip joint prostheses, altered the recommended cutoff for measuring the roughness of the articulating surfaces of the femoral head and acetabular cup but did not encompass two key sites: the bore head and the trunnion. The aim of this study was to evaluate whether the standardized parameters and sites established in ISO 7206-2 are appropriate for evaluating the quality of the surface finish of total hip arthroplasty implants. Three kits containing the polymeric acetabular components, metallic heads, and stems from 5 manufacturers were used for testing. Contact profilometry was performed on the internal acetabular cup, external head, head bore, and trunnion surfaces. Additionally, the external head surface was evaluated with an interferometer to increase the accuracy. The evaluation of the external surface of the femoral head with a profilometer seems to be inadequate, because of a limitation of the contact method associated with highly polished surfaces. The average roughness (Ra) values obtained with an interferometer were lower than those measured with the profilometer and revealed significant differences between the manufacturers. The use of an 0.80-mm cutoff is more appropriate for the Ra range normally found for acetabular cups, enhancing the power to detect acetabular cups with inadequate roughness. The absence of a standard for the surface finish of the stem-head interface generates heterogeneity between manufacturers and between samples produced by a single manufacturer, revealing a lack of quality control.

SLIPPED CAPITAL FEMORAL EPIPHYSIS ACETABULAR ORIENTATION AND SHAPE: A THREE-DIMENSIONAL CT STUDY

Background:Previous studies have analyzed the acetabulum in patients affected by slipped capital femoral epiphysis (SCFE), however controversy remains over how the acetabular shape may be altered in hips experiencing SCFE. In particular, changes in acetabular over-coverage and acetabular version are thought to contribute to SCFE.Hypothesis/Purpose:The purpose of this study was to determine the acetabular morphology in hips with SCFE and compare them to normally developing children.Methods:Images from patients with the diagnosis of SCFE who had a computed tomography (CT) exam of their pelvis were compared to images from an age- and sex-matched cohort of patients with CT exams of the pelvis/abdomen for a non-orthopedic related evaluation (controls). Three dimensional (3D) reconstructions were created from each CT exam (MIMICs software). Custom MATLAB software was used to uniformly align and calculate acetabular parameters from the 3D reconstructions. The acetabular parameters calculated were articular surface area, acetabular tilt, acetabular version, and acetabular coverage angles measured in a radial fashion in 5 out of 8 octants.Results:Two-hundred-ninety-eight hips were evaluated, including 67 hips with SCFE, 39 unaffected contralateral hips in patients with SCFE, and 192 normal controls. The SCFE group consisted of 33 males and 34 females. Acetabular version was similar amongst all SCFE affected hips, unaffected contralateral hips, and normal controls (p=0.575). Control hips had higher acetabular tilt than SCFE affected hips (p=0.001) and unaffected contralateral hips (p=0.012). Acetabular surface area was higher in SCFE affected hips compared to controls (p=0.003)(Table 1). SCFE affected hips had significantly increased acetabular coverage compared to controls in the superior, superior-anterior, and anterior octants (p<0.01). The unaffected contralateral sides had significantly increased acetabular coverage compared to controls in all five regions (p<0.02)(Table 2).Conclusions:Contrary to some previous studies, we did not find the acetabulum to be retroverted in hips with SCFE compared to normal hips. Both the affected and unaffected hips of SCFE patients have decreased acetabular tilt. Acetabular surface area is high in both the affected and unaffected sides in SCFE, suggesting it may be involved in the pathogenesis of the condition. There is increased acetabular coverage in the superior regions of SCFE hips. The shared morphological characteristics of both affected and unaffected sides in SCFE patients suggest that their hip anatomy may predispose them to slips.

Acetabular development and fate of inverted limbus in rabbits: Experimental observation from an animal model.

Using an animal model, we aimed to investigate the effects of an inverted limbus on acetabular development following closed reduction of developmental dysplasia of the hip (DDH). We interpositionedthe menisci of 5-week-old rabbits (n = 40) into the hip joints to simulate limbus inversion following closed reduction for DDH. The acetabular index (AI) on anteroposterior pelvic radiographs and magnetic resonance imagingwere used to evaluate acetabular development. Animals were euthanized at 4 and 8 weeks after surgery. Histological sections of the acetabular cartilage were stained and scored in accordance with the modified Mankin system. Scanning electron microscopyand transmission electron microscopywere used to examine the ultrastructure of the acetabular cartilage. Terminal deoxynucleotidyl transferase dUTP nick end-labelingstaining was used to evaluate chondrocyte apoptosis. Immunohistochemistry and Western blot analyses were used to examine the expression of type X collagen (Col-X) and matrix metalloproteinase 13 (MMP-13) in the acetabular cartilage. AI values increased over a period and were higher in the experimental group than in the sham group. In the experimental group, the acetabular surface had become rough and had split in some cases. Chondrocytes within the acetabular cartilage had become hypertrophic, gradually forming clusters, and taking on an apoptotic appearance. Col-X and MMP-13 expression also increased with time. Our findings suggest that residual limbus inversion following closed reduction for DDH can cause progressive dysplasia of the acetabulum, apoptosis of acetabular chondrocytes, accelerated cartilage degeneration, and even early-stage osteoarthritis.

"Anterior-shift sign": a novel MRI finding of adult hip dysplasia.

In adult hip dysplasia, methods for direct evaluation of hip instability have not been established. The present study aimed to determine findings suggestive of hip instability on magnetic resonance imaging (MRI) and to evaluate their correlations with clinical and radiological factors. We retrospectively reviewed 72 hips in 50 patients with hip dysplasia (45 females, 5 males; mean age: 40.0years; age range: 15-59years; Kellgren-Lawrence grade: ≤ 2). Hip dysplasia was defined as a lateral center-edge angle < 25°. Among the hips, 50 had pain (symptomatic dysplasia group) and 22 were asymptomatic (asymptomatic dysplasia group). As controls, 12 normal hips in 12 patients who underwent screening for asymptomatic osteonecrosis of the femoral head by MRI were evaluated. Using an oblique axial view on fat-suppressed T2-weighted images, we evaluated the presence of a gap between the posterior part of the femoral head and the corresponding acetabular surface, indicating hip instability (anterior-shift sign). The correlations of anterior-shift sign with clinical and radiographical factors were examined. Anterior-shift sign was observed in 92.0% in the symptomatic dysplasia group, 9.1% in the asymptomatic dysplasia group, and 0% in the control group. In adult hip dysplasia, cases with anterior-shift sign had significantly more pain and labrum tear occurrence than cases without anterior-shift sign. Anterior-shift sign was correlated with Kellgren-Lawrence grade and degree of acetabular coverage. This study suggested that hip instability can be observed as the anterior-shift sign on MRI. This sign is useful when considering indications for periacetabular osteotomy in adult hip dysplasia.

The morphological variation of acetabular defects in revision total hip arthroplasty-A statistical shape modeling approach.

Classification and evaluation of acetabular defects remain challenging and are primarily based on qualitative classification methods. That is because quantitative techniques describing variations of acetabular defects and accompanying bone loss volume are not available. This study introduces a new method based on statistical shape models (SSMs) to quantitively describe acetabular defects. This method is then applied to 87 acetabular defects to objectively describe the variations in acetabular defects typically encountered during revision total hip arthroplasty. The absolute bone loss volume, relative bone loss volume, and relative bone loss surface area with respect to the SSM-based pre-diseased anatomy were used to quantify the acetabular bone defects in different segments of the acetabular surface. The absolute bone loss volume of the average defect shape was equal to 37.0 cm3 . The first three principal modes, accounting for 62% of the total shape variation, were found to represent variations in acetabular defect morphology. The first, second, and third principal modes described, respectively, the size of the bone defects, the difference between superomedially and superolaterally migrated defects, and the degree of involvement of the posterior or anterior column. The developed SSM and the introduced approach could be used to create automated and unbiased classification methods based on quantitative data. Moreover, the proposed model and the underlying data provide the basis for a quantitative design approach where the shape and size of new acetabular implants are determined according to clinical variation present in acetabular defects.

Three-dimensional Analysis of Acetabular Morphology and Orientation in Patients With Slipped Capital Femoral Epiphysis.

Previous studies analyzing the acetabuli in patients with slipped capital femoral epiphysis (SCFE) have not definitively addressed the relationship between SCFE and acetabular shape. Femoral head overcoverage and acetabular version are thought to contribute to SCFE. The purpose of this study was to determine the acetabular morphology and orientation in hips with SCFE and compare them with normally developing children. Pelvic computed tomography (CT) images of patients with SCFE were compared with pelvic CTs of patients without orthopedic abnormalities (normal controls). Three-dimensional (3-D) reconstructions were created from each CT examination. Custom software uniformly aligned the pelvis then determined acetabular measures from the reconstructions including acetabular version, acetabular tilt, articular surface area, and acetabular coverage angle measured in a radial manner dividing the acetabulum into octants. Two-hundred forty-four hips were included (53 SCFE, 31 unaffected contralateral hips in patients with SCFE, and 160 controls). The acetabular version was similar among SCFE hips, unaffected contralateral hips, and normal controls (P=0.48). Control hips had higher acetabular tilt than SCFE-affected hips (P=0.01) and unaffected contralateral hips (P=0.04). The acetabular surface area was higher in SCFE-affected hips compared with controls (P<0.05). SCFE-affected hips and the unaffected contralateral hips in patients with SCFE had increased acetabular coverage compared with controls in all 5 acetabular octants. Contrary to some previous studies, the authors did not find the acetabulum to be retroverted in patients with SCFE compared with controls. Both affected and unaffected hips of patients with SCFE have decreased acetabular tilt. Acetabular surface area is higher in hips with SCFE compared with normal controls, and both the SCFE-affected hips and unaffected hips had increased acetabular coverage compared with controls in all 5 octants of the acetabulum. The shared morphology of affected and unaffected hips in patients with SCFE suggests that their acetabular anatomy may predispose them to slip. Level III.

Poor delineation of labrum and acetabular surface on arthrogram is a predictor of early failure of closed reduction in children aged six to 24 months with developmental dysplasia of the hip.

PurposeThe objective of this study was to explore the predictors for failed reduction in children with developmental dysplasia of the hip (DDH) managed by arthrogram, closed reduction (CR) and spica cast immobilization.MethodsWe retrospectively reviewed the clinical data of patients with DDH treated by CR and cast immobilization (2015-2020), including age, sex, affected side, presence/absence of an ossific nucleus, International Hip Dysplasia Institute classification, the delineation of labrum and acetabular surface on arthrogram, inverted labrum, acetabular index (AI), hip abduction angle and medial dye pool (MDP) distance. Predictors that potentially predicted failure of CR were evaluated by logistic regression analysis, simple t-test, Fisher’s Exact Test and chi-square test.ResultsIn total, 16 out of 187 hips failed to achieve initial CR (8.6%). Gender, age, preoperative AI and poor delineation of arthrogram were candidate predictors for failed CR in children aged six to 24 months with DDH; on the other hand, logistic regression analysis confirmed age and poor delineation of arthrogram significantly predicted failure of CR. Receive operating characteristic curve (ROC) showed MDP less than 6 mm and age higher than 14.5 months significantly increased the failure rate of CR in children aged six to 24 months with DDH.ConclusionAge and poor delineation of labrum and acetabular surface during arthrogram predicted failure of CR in children with DDH. In particular, age > 14.5 months and MDP distance ≥ 6 mm significantly increased the risk of CR failure.Level of evidenceIII

Finite element analysis of evaluating the change of the hip joint biomechanics following femoral neck shortening after cannulated screw fixation for osteoporotic femoral neck fracture

Objective: To evaluate the stress status of femoral head and neck, screws and acetabulum caused by femoral neck shortening after internal fixation of femoral neck fracture with finite element method, and to analyze the stress of proximal femoral neck and acetabulum from the mechanical point of view. Methods: CT scan data of hip of a healthy adult female were collected. Three-dimensional reconstruction MICs and related module function simulation was used to establish the postoperative shortening model of femoral neck fracture with Pauwells angle>50°, which was treated with cannulated screws. The models were divided into four groups: normal femoral neck without shortening, shortening for 2.5 mm, shortening for 7.5 mm and shortening for 12.5 mm. The finite element analysis software MSC. Nastran2012 was used to do the mechanical analysis. The acetabulum surface, femoral head surface, proximal femur and the maximum stress, stress nephogram and other relevant data were collected. Results: The maximum tensile stress and the maximum stress at the fracture site of the femoral neck increased gradually with the increasing of shortening of femoral neck, however, the maximum compressive stress under the femoral neck and the medial cortex decreased gradually; the maximum stress on the surface of the femoral head was 14.9, 15.0, 16.3 and 16.3 MPa, respectively; the maximum stress on the surface of the acetabulum was 10.1, 10.1 and 10.5,11.7 MPa, respectively. Conclusion: The mechanical environment of the hip joint changes with femoral neck shortening. With the increasing of femoral neck shortening, the peak stress of the acetabulum increases continuously. When the femoral neck is shortened seriously, the load distribution is uneven and the complex mobility of hip joint is decreased. In addition, the change of shortening might play a role in the necrosis of femoral head.

Why Make the Cut? Trochanteric Slide Osteotomy Can Improve Exposure to the Anterosuperior Acetabulum.

To define relative increases in visual bony surface area and access to critical landmarks with the addition of a trochanteric slide osteotomy to a Kocher-Langenbeck approach. A Kocher-Langenbeck approach followed by a trochanteric slide osteotomy was sequentially performed on 10, fresh-frozen, hemipelvectomy cadaveric specimens. Visual and palpable access to relevant surgical landmarks was recorded. Calibrated digital photographs were taken of each approach and analyzed using Image J. The acetabular surface area exposed was 27.66 (±6.67) cm2 for a Kocher-Langenbeck approach. This increased to and 41.82 (±7.97) cm2 with the addition of a trochanteric osteotomy. The exposed surface area was increased by 51.2% for the trochanteric osteotomy (P < 0.001). The superior margin of the acetabulum could be visualized and palpably accessed in both exposures. Access to the more anterosuperior portions of the acetabulum was consistently possible in the trochanteric osteotomy but not with the Kocher-Langenbeck approach. A trochanteric osteotomy may visually improve access to the most anterosuperior acetabulum but does not significantly improve surgical access to relevant portions of the superior acetabulum when compared with a Kocher-Langenbeck approach.