Search

Background: The relationship between hip morphological changes and joint concentricity in infants with late-detected developmental dysplasia of the hip (DDH) treated with gradual reduction remains unclear. Therefore, we investigated hip morphological changes and concentricity in infants with late-detected unilateral DDH using magnetic resonance imaging (MRI) during gradual reduction. Methods: We enrolled 20 infants aged ≥ 12 months with unilateral DDH. Treatment comprised continuous traction, a hip-spica cast, and an abduction brace. MRI was performed before treatment, immediately after hip-spica cast placement, after cast removal, and at the end of the brace. We evaluated the acetabulum and femoral head morphology and joint concentricity. Results: The mean age was 25 months, and female sex and the left side were predominant. Before treatment, the acetabulum was small and shallow and the femoral head was spherically flat on the affected side. Immediately after the continuous traction, the affected acetabulum and femoral head were still smaller than the healthy/contralateral one. However, they improved to a deeper acetabulum and round femoral head. Intra-articular soft tissue (IAST) and femoral–acetabular distance (FAD) continuously decreased, indicating gradual improvement in joint concentricity. Deeper formation of the acetabulum and round shaping of the femoral head had occurred even in non-concentric reduction. Conclusion: The shape and concentricity of the hip joint improved after treatment; however, the acetabulum and femoral head remained small. The deeper acetabulum and round femoral head were observed the non-concentric reduction before the concentric reduction was achieved. The continuous decrease in IAST and FAD indicates effective post-traction therapy. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to investigate the radiographic findings for the hip joint and hip range of motion in professional cyclists, and to determine their bone morphology and physical characteristics. The effects of physical characteristics on athletic performance were examined in terms of metabolic efficiency using simulation analysis. Methods: We performed a case–control research study on 22 hips in 11 male professional cyclists (average age 28.5, height 1.73 m, weight 77.6 kg). Thirty hips in 15 healthy male volunteers were selected as controls. As radiographic evaluations, acetabular dysplasia was assessed on standardized radiographs. During physical evaluations, the hip range of motion was examined. We used simulation analysis to investigate the metabolic efficiency in the different cycling forms. Results: The radiographic evaluations showed a significant difference in the incidence of acetabular dysplasia (p = 0.01): 59% (13/22 hips) in the pro-cyclist group versus 10% (3/30 hips) in the control group. The physical evaluations revealed significant differences in the hip internal rotation angle (p = 0.01), with greater ranges of internal rotation in the pro-cyclist group versus the control group. The simulation analyses showed that metabolism was reduced in the cycling form with hip internal rotation, especially in the lower extremities. Conclusions: Pro-cyclists showed a high frequency of acetabular dysplasia and superior hip internal rotation. According to the cycling model analyses, hip internal rotation allowed pedaling with reduced metabolic power. [ABSTRACT FROM AUTHOR]

Simple Summary: Simple Summary: Water mites are a significant population of Arachnida in aquatic ecosystems, with over 7500 species described worldwide. The genus Unionicola, belonging to the family Unionicolidae, is known for its parasitic behavior, often consuming the mucus and tissue of its molluscan hosts. While most species in this genus parasitize mussels, some have been found in gastropods. In our study, we discovered water mites infesting two species of gastropods: Filopaludina sumatrensis polygramma and F. martensi martensi. Through a comparison with known species, we identified this mite as a new species within the genus Unionicola, subgenus Polyatax, and named it "Unionicola (Polyatax) kasetbangkhenensis sp. nov.". Two species of gastropods, Filopaludina sumatrensis polygramma and F. martensi martensi, were found infested with water mites of the genus Unionicola in Bangkok and Nonthaburi provinces, Thailand. Morphological studies on these water mites, based on the characteristics of their genital acetabular and female genital fields, identified them as a new member of subgenus Polyatax. Unionicola (Polyatax) kasetbangkhenensis sp. nov. was named after the first location where this parasitic water mite was discovered. This species is distinguished from others by the pattern of their female genital field, with their anterior acetabular plates each bearing two acetabula and a short thick spine on the inner margin. Additionally, it differs from other species by the structure of the spines in its pedipalps and legs, as well as in the shapes of its coxal plates. [ABSTRACT FROM AUTHOR]

Background: Delayed operative fixation of acetabular fractures remains a major problem in many parts of the world. No previous studies have reported the effect of fixation delay on health-related quality of life (HRQOL). We aimed to investigate the effect of delayed operative fixation of acetabular fractures on health-related quality of life, EuroQol-5 Dimension questionnaire (EQ-5D), and other related outcomes. Methods: We retrospectively analysed 117 patients who underwent open reduction internal fixation for displaced acetabular fractures between 2014 and 2021. Patients were divided into groups based on the admission-to-surgery time (interval between injury and definitive surgery): 1–14, 15–21, and >21 days. Patients were analysed for associations between admission-to-surgery time and postoperative outcomes, including operative time, estimated blood loss, blood transfusion, postoperative complication, and quality of reduction. Eighty-five patients with a mean follow-up time of 3.94 ± 1.84 years were analysed for the association between admission-to-surgery time and conversion to total hip arthroplasty, the Modified Merle d'Aubigné and Postel score, EQ-5D score, ability to sit cross-legged, and ability to sit squat. Multivariable linear regression was used for continuous outcomes and logistic regression for categorical outcomes associated with delayed operative fixation. Results: An admission-to-surgery time > 14 days was associated with significantly higher blood loss [785 mL (236–1335), p = 0.006]. For associated fractures, an admission-to-surgery time > 21 days increased the risk of poor reduction [odds ratio (OR), 5.21 (1.42–19.11), p = 0.013]. Further, admission-to-surgery time > 21 days was associated with poor Modified Merle d'Aubigné and Postel scores [OR, 8.46 (1.48–48.29), p = 0.016], EQ-5D pain domain [OR, 3.55 (1.15–11), p = 0.028], and EQ-5D usual activity domain [OR, 4.24 (1.28–14), p = 0.018]. Conclusion: Delayed operative fixation of acetabular fractures after 21 days affected the functional outcomes and HRQOL, independent of the reduction status. Surgical interventions and patient referrals should occur at the earliest and within 21 days from the time of injury. [ABSTRACT FROM AUTHOR]

Objectives: The acetabular cup design plays a critical role in reducing contact stress between femur head acetabular cup. Many studies used ellipsoidal and spheroidal geometry in acetabular cup design to effectively reduce contact stress. The present study focuses on elevated acetabular cup rim with round corner design to reduce contact stress with round corner geometry. Methods: The cobalt chromium femur head and cup are considered for finite element (FE) model of hip resurfacing. The gait loads of routine activities of humans like normal walking, stair ascending and descending and sitting down and getting up gait activities are applied to the developed 3D FE model. Five microseparations of 0.5, 1, 1.5, 2 and 2.5 mm are considered in the present study. The acetabular cup inclination angle considered for this study are 35°, 45°, 55°, 65° and 75°. The contact stress and von Mises stress plot for each gait activities under these microseparations are analyzed for betterment of longevity of implants. Results: Overall elevated cup rim design helped in reducing contact stress to a greater extent than conventional cup with different geometries. Also, the predicted von Mises stress for all the parameters considered in the current study are well within the yield strength of CoCr material. Therefore, elevated cup rim could be used as a better alternative to spline and, ellipsoidal and circular geometries of cup. [ABSTRACT FROM AUTHOR]

Objective: To digitally measure the fixation trajectory of anatomical plates used in the combined reduction of quadrilateral acetabular fractures via the posterior approach, and to develop anatomical plates that align with the characteristics of the pelvis in the Chinese population. Methods: Pelvic computed tomography (CT) data from 102 adult patients were collected at the Affiliated Hospital of Zunyi Medical University. This group included 51 males and 51 females, aged between 20 and 60 years. Using Mimics software (version 21.0), a three-dimensional model of each pelvic data point was reconstructed. The fixation path for the combined reset anatomical steel plate was drawn, where the curves on the fixation path were approximated as arcs. The radius of curvature and length of these curves were measured, and an anatomical steel plate was designed to best fit the pelvic structure. Results: The combined anatomical reduction plate fixation system for quadrilateral acetabular fractures using a posterior approach consisted of two parts: a locking plate and a reduction plate. The posterior wall region (r2), ischial region (r3), quadrilateral region (r4), and bending region (r5), and the total length of the reduction plate were significantly smaller in females (P < 0.05). Similarly, the posterior wall region (R3), distal posterior wall region (R4), and the total length of the locking plate were significantly smaller in females (P < 0.05). Additionally, the anterior superior iliac spine side (r1) and the total length of the T-shaped auxiliary plate were significantly smaller in females (P < 0.05). The bending angle (< A) was also significantly smaller in females (P < 0.05). Conclusions: The pelvic surface structure is irregular and varies greatly among individuals.Compared to the traditional steel plate, The combined reduction anatomical plate designed in this study demonstrated high precision and improved conformity to the anatomical structure of the pelvis. [ABSTRACT FROM AUTHOR]

Background: This retrospective cross-sectional study investigated the cutoff values (COVs) for developmental dysplasia of the hip (DDH) using a three-dimensional (3D) pelvic model reconstructed using computed tomography (CT). We included 107 healthy Japanese participants and 73 patients who had undergone curved periacetabular osteotomy (CPO) for DDH between 2012 and 2017. Methods: The hip CT images were adjusted to the anterior pelvic plane (APP), functional pelvic plane (FPP), sagittal anterior center-edge angle (ACEA), and sagittal posterior center-edge angle (PCEA). The lateral center-edge angle (LCEA), acetabular roof obliquity (ARO), anterior acetabular sector angle (AASA), and posterior acetabular sector angle (PASA) were measured. Receiver operating characteristic (ROC) curves were used to calculate the COVs, and the association between the parameters was analyzed using multiple logistic regression. Results: The ARO (≥10.2°) and LCEA (≤22.2°) were independent influencing factors for the APP, whereas the AASA (≤53.1°) and LCEA (≤24.5°) were independent influencing factors for the FPP. Conclusions: The 3D criteria for the diagnosis of DDH in Japanese individuals can identify DDH with insufficient anterior coverage, which anteroposterior plain radiographs cannot visualize, and can help determine indications for acetabular osteotomy. [ABSTRACT FROM AUTHOR]

Objective: Combined with open reduction through medial adductor approach, Salter innominate osteotomy (SIO) and Pemberton pericapsular osteotomy (PPO) methods are common procedures for the repair of incomplete acetabulum structure in patients with developmental hip dysplasia (DHD). The aim of this study is to compare the outcomes of acetabulum development in patients treated using these two methods. Patients and Methods: We retrospectively reviewed the medical records of 50 (65 hip joints) children who underwent SIO or PPO for DHD. Thirty-three patients underwent SIO and 32 patients underwent PPO as surgical treatment. The criteria of Tönnis, modified McKay, and Severin, and angles of acetabular index (AI) and acetabular center-edge (CE) angles of both groups were compared. Results: There were significant differences between two groups in the time of operation, follow-up time after operation, preoperative and postoperative AI angles, and postoperative 1styear CE angles. AI was detected as lower in the PPO group at 1stmonth postoperatively. Whereas, mean AI was detected as higher in the preoperative PPO group. In addition, the acetabular CE angle was significantly lower in the PPO group at 1styear postoperatively. However, there was no significant difference between the groups in terms of the CE angle value measured at the final follow-up. Conclusion: Salter innominate osteotomy and PPO methods used in the treatment of DHD have specific advantages and disadvantages. Preoperative and intraoperative evaluations of patients are very important in determining which procedure should be performed. When the choice is made properly, clinical and radiological results are both satisfactory. [ABSTRACT FROM AUTHOR]

Background: Operative treatment of acetabular fractures generally yields good results, but several authors report up to 15–20% of patients developing post-traumatic osteoarthritis (OA). Previous studies have shown that total hip arthroplasty (THA) following post-traumatic OA have inferior results compared to THA for primary OA. The aim of this study was to report on long-term outcome of THA following acetabular fracture, compared to primary OA. Materials and methods: We performed a matched cohort study with data from the Norwegian Arthroplasty Register (NAR). All patients receiving THA following an acetabular fracture between 1987 and 2018 were identified. A 3:1 matched cohort consisting of patients treated for primary OA with THA was selected using propensity scores and matched for age, gender and year of surgery. Survival analysis was performed with revision of any cause as endpoint. Cox regression was used to identify factors associated with risk of revision surgery. Results: 552 cases were identified, 397 men and 155 women. Mean age was 58.8 (11–91) years. 224 had previously been operated for the acetabular fracture, 328 had been treated non-operatively. Mean follow up time was 8.7 (1–29) years. Implant survival at 10 years was 79.7% (75.6–83.3) and at 20 years 62.4% (55.5–69.3). The hazard ratio for revision was 1.38 (1.07–1.77, p < 0.001) compared to the OA cohort, regardless of operative or non-operative treatment of the index acetabular fracture. Uncemented acetabular components had an increased risk of revision with hazard ratio for revision 1.61 (p = 0.012). Conclusions: THA following an acetabular fracture can be performed with acceptable results regarding implant survival, however, we report an increased risk for revision when compared to primary OA. Our results indicate that previous operative fracture treatment does not increase the risk for THA revision compared to cases treated non-operatively. [ABSTRACT FROM AUTHOR]

Background: The choice between total hip arthroplasty (THA) and hemiarthroplasty (HA) to treat displaced femoral neck fractures, particularly among the elderly, is still controversial. Acetabular erosion consists of a late multifactorial process that may happen after hip HA resulting in significant postoperative burden. This study aims to investigate the impact of acetabular erosion progress after hip HA in patients over 70 years old. Materials and methods: This is a 5-year (2013–2018) retrospective study including consecutive series of patients >70 years who were treated with bipolar hip HA for femoral neck fractures. Patients were categorised into 3 groups for analysis (A = 70–75 years, B = 75–80 years, C = >80 years). The study enrolled a total number of 813 patients who met the inclusion criteria. We assessed acetabular erosion through radiological examinations and measured functional deterioration using the modified Harris Hip Score (mHHS) at 6 and 12 months follow-up. Our comprehensive investigation extended over a maximum period of 5 years. The correlation of patients' characteristics and HA features on erosion progress was assessed. Results: There were no significant differences in sex distribution, injury side, BMI, ASA score, bipolar head diameter, mHHS and leg-length discrepancy among the groups (p > 0.05). During the follow-up period, acetabular erosion with consequential conversion to THA was observed in 6.13%, 4.22% and 1.96% for Groups A, B and C respectively (p = 0.009). A statistically significant difference of acetabular erosion was observed in Group A compared to patients of Group C. Conclusions: Age constitutes a significant factor of acetabular wear after HA in the elderly. The higher rate of acetabular wear in patients <75 years suggests that THA is a more viable option, as HA is for patients >80 years old. [ABSTRACT FROM AUTHOR]

Background: The Hueter-Anterior Approach (HAA) with its limited soft tissue and internervous dissection has been shown to be an effective approach for primary total hip and hip resurfacing arthroplasty (HRA). The purpose of this study is to evaluate the clinical outcome of patients requiring revision of HRA to total hip replacement using the HAA, assessing function and complications. Methods: We performed a retrospective review of a prospectively maintained research database. Between 2006 and 2015, 555 primary metal-on-metal (MoM) HRAs were performed via the HAA; we identified 33 hips in 30 patients that required revisions for aseptic causes to THA: aseptic loosening of acetabulum in 12 and femoral in 7, 10 for pseudotumour/ALTR, 4 for femoral neck fracture. All revision surgeries were performed through a HAA by a single surgeon who had also performed the index operation. PROMs were collected preoperatively and yearly at various timepoints postoperatively. Results: The mean age at time of revision was 48.9 years (±5.3 SD) for 22 males (67%) and 11 females (33%). The mean time to revision surgery/failure of hip resurfacing was 3.3 years (±2.4 SD). There were 5 major reoperations with 3 infections, 1 acetabular loosening and 1 trunnionosis. There were significant improvements in multiple PROMs. Conclusions: The HAA is a viable surgical approach for revision of HRA with smaller initial HRA acetabular components generally requiring a relatively larger acetabular compoent at time of revision. Patients reported improvement in symptoms and function and a lower risk of subsequent reoperation than what has previously been reported for failed MoM bearings. [ABSTRACT FROM AUTHOR]

Background: Persisting groin pain post total hip arthroplasty (THA) is a common and complex issue that can be difficult to diagnose and manage. Acetabular component positioning is often implicated. Aims and methods: We used a previously well described and validated functional positioning protocol to determine if functional acetabular malpositioning was a factor in groin pain post THA and hence to determine if acetabular revision would be indicated. We compared patient-specific functional acetabular positioning to traditional CT evaluation of cup position and assessment of anterior cup overhang. Results: 39 patients with groin pain post-THA were investigated. Functional acetabular malpositioning was diagnosed in 31% (12/39). Revision THA was performed in those 12 patients, resulting in resolution of functional malpositioning (100%), with an overall accuracy of 5.6° (range 1–12), and resolution of groin pain in 67% (8/12). 33% (4/12) of the revised implants had functional positioning located outside the traditional "40/20 zone". Comparison with CT indicated that 40% (4/10) of implants with anterior overhang were well positioned, however only 50% (6/12) of functionally malpositioned implants had CT evidence of anterior cup prominence. Of the 8/12 revision patients who had resolution of their groin pain, only 1 had cup prominence. Conclusions: This study suggests that the utilisation of a patient specific functional positioning algorithm in the analysis of persistent groin pain following THA can assist in identifying the underlying cause of pain and help to guide treatment. For a functionally malpositioned acetabulum, revision surgery offers a potential resolution of groin pain. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to investigate the accuracy of cup position and assess the changes in pelvic tilt during primary total hip arthroplasty (THA) in the lateral decubitus position using a new computed tomography (CT)-based navigation system with augmented reality (AR) technology. Materials and methods: There were 37 cementless THAs performed using a CT-based navigation system with AR technology in the lateral decubitus position and 63 cementless THAs performed using manual implant techniques in the lateral decubitus position in this retrospective study. Postoperative cup radiographic inclination and anteversion were measured using postoperative CT, and the proportion of hips within Lewinnek's safe zone was analyzed and compared between the two groups. The mean absolute values of navigation error were assessed. Intraoperative pelvic tilt angles were also recorded using navigation system. Results: The percentage of cups inside Lewinnek's safe zone was 100% in the navigation group and 35% in the control group (p < 0.001). The mean absolute values of navigation error in inclination and anteversion were 2.9° ± 2.1° and 3.3° ± 2.4°, respectively. The mean abduction angle of the pelvis was 5.1° ± 4.8° after placing the patients in the lateral decubitus position and 4.1° ± 6.0° after cup placement. The mean posterior tilt angle was 6.8° ± 5.1° after placing the patients in the lateral decubitus position and 9.3° ± 5.9° after cup placement. The mean internal rotation angle was 14.8° ± 7.4° after cup placement. There were no correlations between the navigation error in inclination or anteversion and the absolute values of changes of the pelvic tilt angle at any phase. Conclusions: Although progressive pelvic motion occurred in THA in the lateral decubitus position, especially during cup placement, the CT-based navigation system with AR technology improved cup placement accuracy. [ABSTRACT FROM AUTHOR]

Background: Minimally invasive percutaneous screw fixation for pelvic ring and acetabular fractures has become increasingly popular due to its numerous benefits. However, the precise placement of the screw remains a critical challenge, necessitating a modification of the current techniques. This paper introduces a refined technique employing a modified guidewire to enhance the precision and efficiency of percutaneous fixation in pelvic and acetabular fractures. Methods: This study details the surgical techniques implemented for correcting guidewire misdirection in percutaneous screw fixation and includes a retrospective analysis of patients treated with this modified approach over a three-year period. Results: In this study, 25 patients with pelvic ring and acetabular fractures underwent percutaneous screw fixation. The cohort, predominantly male (23 out of 25), had an average age of 38 years. The majority of injuries were due to traffic accidents (18 out of 25). Types of injuries included pelvic ring (6 cases), acetabular fractures (8 cases), and combined injuries (11 cases). Various screw types, including antegrade and retrograde anterior column screws, retrograde posterior column screws, and lateral compression screws, were used, tailored to each case. Over an average follow-up of 18 months, there were no additional procedures or complications, such as neurovascular injury or hardware failure, indicating successful outcomes in all cases. Conclusions: This study introduces a simple yet effective method to address guidewire misdirection during percutaneous fixation for pelvic and acetabular fractures, offering enhanced precision and potentially better patient outcomes. Further research with a larger patient cohort is required for a more comprehensive understanding of its efficacy compared to traditional methods. Level of evidence : IV. Therapeutic Study (Surgical technique and Cases-series). [ABSTRACT FROM AUTHOR]

Purpose: Obesity is an epidemic which increases risk of many surgical procedures. Previous studies in spine and hip arthroplasty have shown that fat thickness measured on preoperative imaging may be as or more reliable in assessment of risk of post-operative infection and/or wound complications than body mass index (BMI). We hypothesized that, similarly, increased local fat thickness at the surgical site is a predictor of wound complication in acetabulum fracture surgery. Methods: Patients who underwent open reduction and internal fixation (ORIF) of an acetabulum fracture through a Kocher-Langenbeck (K-L) approach at a single institution from 2013 to 2020 were identified. Pre-operative CT scans were used to measure fat thickness from the skin to the greater trochanter in line with the surgical approach. Post-operative infections and wound complications were recorded and associated with fat thickness and BMI. Results: 238 patients met inclusion criteria. 12 patients had either infection or a wound complication (5.0%). There was no significant association with BMI or preoperative fat thickness on post-operative infection or wound complication (p-value 0.73 and 0.86). Conclusions: There is no statistically significant association of post-operative infection or wound complications in patients with increased soft tissue thickness or increased BMI. ORIF of acetabulum fractures through a K-L approach can be performed safely in patients with large subcutaneous fat thickness and high BMI with low risk of infection or wound complications. [ABSTRACT FROM AUTHOR]

Purpose: Acetabular fractures are highly complex injuries often resulting from high-energy trauma. The gold standard treatment for these injuries has become open reduction internal fixation (ORIF). The purpose of this study is to further this understanding and investigate how (1) patient demographics and (2) patient-specific risk factors affect 90-day readmission rates. Methods: A retrospective, nationwide query of private insurance database from January 1st, 2010 to October 31st, 2020 was performed using ICD-9, ICD-10, and CPT codes. Patients who underwent acetabular ORIF and were readmitted within 90 days following index procedure were included, patients who were not readmitted served as controls. Patients were divided by demographics and specific risk factors associated with readmission. Results: The query yielded a total of 3942 patients. Age and sex were found to be non-significant contributing risk factors to 90-day readmissions. Data also showed that statistically significant comorbidities included arrhythmia, cerebrovascular disease, coagulopathy, fluid and electrolyte abnormalities, and pathologic weight loss. Conclusion: This study illustrated how several patient-specific risk factors may contribute to increased 90-day readmission risk following acetabular ORIF. A heightened awareness of these comorbidities in patients requiring acetabular ORIF is required to improve patient outcomes and minimize rates of readmission. Further investigation is needed to improve patient outcomes, and increase awareness of potential post-operative complications in these higher-risk patient populations. [ABSTRACT FROM AUTHOR]

Background: There is no consensus regarding the treatment of symptomatic hip dysplasia in adolescents and adults. Most previous studies have insufficient follow-up time. Aim: The aim of this study was to assess the long-term outcome of a modified Spitzy shelf procedure. Methods: We reviewed 79 adults with 94 acetabular shelf operations between 1976 and 2000. Mean age at surgery was 33.7 years (range 13–54). Indication for surgery was acetabular dysplasia with or without hip pain. Outcome was evaluated using hip pain pre- and postoperatively and Kaplan–Meier survival analysis with conversion to total hip replacement (THR) as the endpoint. Results: Hip pain was reported in 84% of the hips preoperatively and in 21% one year postoperatively. 63 hips (65%) had undergone THR at a mean patient age of 54.3 years (range 29–76). The mean survival time from Spitzy operation to THR was 17.2 years (range 1–39). Survival was 86% at 10-year follow-up, 56% at 20-year follow-up, and 36% at 30-year follow-up. Predictors of THR were age at surgery ≥ 30 years and preoperative osteoarthritis (OA). The rate of complications was 12%, but most were mild to moderate. Conclusions: The modified Spitzy shelf operation had a good effect on hip pain. The long-term survival with conversion to THR as the endpoint in hips without preoperative OA was similar to that reported after periacetabular osteotomy. This indicates that the shelf procedure may be a suitable option in adolescents and young adults with milder degrees of hip dysplasia without OA. [ABSTRACT FROM AUTHOR]

Background: An everted acetabular labrum (EL) is a pathologic variant in which the labrum is flipped to the capsular side of the acetabular rim. An iatrogenic EL is a known complication of a poorly executed labral repair, and a recent study described the native acetabular EL. Purpose: To analyze surgical outcomes after advancement or reconstruction of an EL in a native hip. Study Design: Cohort study; Level of evidence, 3. Methods: This was a multicenter retrospective review of prospectively collected data on primary hip arthroscopic surgeries performed between 2013 and 2023. An EL was identified arthroscopically as a labrum–femoral head gap while off traction in the native hip. All patients with EL who were analyzed in this study underwent arthroscopic labral repair and advancement or labral augmentation or reconstruction. Patients with hip dysplasia also underwent periacetabular osteotomy with or without a derotational femoral osteotomy. Patient-reported outcomes (PROs) were assessed using the 12-item International Hip Outcome Tool (iHOT-12) and the Nonarthritic Hip Score. PROs were obtained preoperatively and up to 24 months after surgery. PROs were compared with those of a case-matched control cohort in a 1:2 ratio. Only patients with PROs available at ≥1 year postoperatively were included in the outcome analysis. Results: A total of 111 patients (129 hips) with EL during the study period were identified, with PROs available in 96 hips. The mean age of patients with EL was 30.5 years, and women made up 87% of the cohort. Of the 129 hips with an EL, an isolated diagnosis of an EL was present in 11.6% of hips. Deficient acetabular coverage (lateral center-edge angle <25°) was seen in 40.6% of EL hips. No difference was seen in iHOT-12 scores between EL and control groups at 12- or 24-month follow-up (P =.18 and.94, respectively). Patients with EL reported a significant improvement of PROs at latest follow-up (P <.001 for iHOT-12 and Nonarthritic Hip Score). Conclusion: Surgical management of a native EL with restoration of the labral seal on the femoral head and correction of concomitant pathologies resulted in significant clinical improvement, with postoperative outcome scores comparable to those of patients without an EL. These findings provide evidence supporting surgical intervention for a native EL. [ABSTRACT FROM AUTHOR]

The vertebrate assemblages of the Albian to Cenomanian Wayan Formation of southeastern Idaho and southwestern Montana's coeval Vaughn Member of the Blackleaf Formation are dominated by the small, burrowing orodromine dinosaur Oryctodromeus cubicularis. Here, we describe in detail the osteology of Oryctodromeus based on new specimens from Idaho and Montana that add substantially to the preliminary description of the types from Montana, and provide a suite of additional diagnostic characters for the taxon: ilium with elongate preacetabular process; elongate cervical vertebra centra with an anteroposterior length 1.6 times the dorsoventral height; elongate dorsal vertebra centra with an anteroposterior length 1.4 times the dorsoventral height; more than 55 elongate caudal vertebrae enveloped in hypaxial and epaxial ossified tendons; and a femoral head on an elongate neck—similar to that of Koreanosaurus—projecting from the greater trochanter at about 35°. The tail, comprising two-thirds of the animal's roughly 3 meters length, and associated tendon sheaths in the axial column indicate greater flexibility than previously supposed for ossified tendons or, alternatively, suggest that the Oryctodromeus burrows had separate, or multiple entrances and exits. The elongated and angled femoral head likely facilitated digging via a braced splayed-leg posture. Our phylogenetic analysis incorporates new characteristics and supports the monophyly of Orodrominae, a clade of neornithischian dinosaurs from the middle to Late Cretaceous of Asia and western North America that utilized burrowing. [ABSTRACT FROM AUTHOR]

Developmental dysplasia of the hip (DDH) presents varying degrees of femoral head dislocation, with severe cases leading to the formation of a new articular surface on the external side of the iliac bone—the neoacetabulum. Despite conventional understanding suggesting otherwise, a tissue resembling hyaline cartilage is found in the neoacetabulum and acetabulum of Crowe III and IV patients, indicating a potential for hyaline cartilage development without mechanical pressure. To test this theory, acetabular and femoral head cartilage obtained from patients with DDH was stained with hematoxylin–eosin and toluidine blue. The immunohistochemical analysis for collagen types II and VI and aggrecan was performed, as well as delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) analysis on a 7.0 T micro-MRI machine. The results obtained from DDH patients were compared to those of the control groups. Hyaline cartilage was found in the neoacetabulum and the acetabulum of patients with DDH. The nature of the tissue was confirmed with both the histological and the MRI analyses. The results of this study proved the presence of hyaline cartilage in patients with DDH at anatomical regions genetically predisposed to be bone tissue and at regions that are not subjected to mechanical stress. This is the first time that the neoacetabular cartilage of patients with advanced stages of DDH has been characterized in detail. [ABSTRACT FROM AUTHOR]

Introduction: Various surgical techniques have been proposed to manage acetabular fractures involving both columns with posterior wall displacement. However, the optimal surgical approach to achieve satisfactory reduction quality remains controversial. Materials and methods: This retrospective study evaluated 34 patients with fractures who were treated at a single medical institution. The patients were divided into two groups according to the ventral/dorsal surgical approach employed: simultaneous (SI) and sequential (SE). Perioperative parameters, as well as radiological and functional outcomes, were analyzed and compared between the two groups. Results: The SI and SE groups comprised 9 and 23 out of the 34 patients, respectively. The SI group exhibited a significantly shorter surgical time and lower estimated blood loss than the SE group (p = 0.04 and 0.03, respectively). The quality of reductions of the anterior and posterior columns was similar between the two groups; however, superior reduction in the fracture gap of the posterior wall was observed in the SI group, as revealed by axial and coronal computed tomography scans. Conclusions: A simultaneous ventral and dorsal approach through the pararectus and the modified Gibson approach confer clinical advantages in reducing the fracture gap, surgical time, and intraoperative blood loss when managing acetabular fractures involving both columns and a displaced posterior wall. Therefore, these surgical approaches may be considered to be optimal for achieving satisfactory reduction quality in such fractures. [ABSTRACT FROM AUTHOR]

Background: Positioning implant components and restoring patient anatomy during total hip arthroplasty (THA) are essential for joint stability, polyethylene liner wear, and range of motion. Previous studies comparing intraoperative fluoroscopy with no fluoroscopy during the posterior or posterolateral approach have reported conflicting results. This meta-analysis evaluated if intraoperative fluoroscopy improves component positioning and femoral component position compared to no fluoroscopy during posterior or posterolateral approach total hip arthroplasty. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards were followed when conducting the systematic review. We searched Web of Science, Embase, PubMed, Cochrane Controlled Trials Register, Cochrane Library, Highwire, CBM, CNKI, VIP, and Wanfang database in May 2023 to identify studies involving Intraoperative fluoroscopy versus no fluoroscopy during posterior or posterolateral approach total hip arthroplasty. Finally, we identified 1133 patients (1145 hips) assessed in seven studies. Results: There were no significant differences in terms of acetabular cup inclination angle (ACIA, P = 0.43), ACIA within safe zone rate (P = 0.58), acetabular cup anteversion angle (ACAA, P = 0.46); ACAA within safe zone rate (P = 0.72), Combined safe zone rate (P = 0.28), dislocation rate (P = 0.64) and infection rate (P = 0.94) between two groups. Compared with the no fluoroscopy group, the intraoperative fluoroscopy group had more operation time (P < 0.00001), less femoral component offset difference (FCOD, P = 0.03), and less LLD (P < 0.00001). Conclusion: Even though intraoperative fluoroscopy was not related to an improvement in cup location or dislocation incidence. Our findings demonstrate that the restoration of leg lengths and femoral offset can be significantly improved by using intraoperative fluoroscopy to supplement good surgical skills in THA. The advantages of intraoperative fluoroscopy might become more apparent for surgeons with less experience. To ascertain whether intraoperative fluoroscopy for posterior or posterolateral approach total hip arthroplasty will have clinical benefits and improve the survival of prostheses, more well-powered and well-designed long-term follow-up studies were necessary. [ABSTRACT FROM AUTHOR]

Introduction: The use of a robotic system for the placement of pedicle screws in spine surgeries is well documented in the literature. However, there is only a single report in the United States describing the use of a robotic system to place two screws in osseous fixation pathways (OFPs) commonly used in the treatment of pelvic and acetabular fractures in a simulated bone model. The purpose of this study was to demonstrate the use of a robotic system to place screws in multiple, clinically relevant OFPs in a cadaveric model and to quantitatively measure accuracy of screw placement relative to the preoperative plan. Methods: A single cadaveric specimen was obtained for the purpose of this study. All surrounding soft tissues were left intact. Screws were placed in OFPs, namely iliosacral (IS), trans-sacral (TS), Lateral Compression-II (LC-II), antegrade anterior column (AC) and antegrade posterior column (PC) of the right hemipelvis using standard, fluoroscopically assisted percutaneous or mini-open technique. Following the placement of screws into the right hemipelvis using standard techniques, screws were planned and placed in the same OFPs of the contralateral hemipelvis using the commercially available ExcelsiusGPS® robotic system (Globus Medical Inc., Audubon, PA). After robotic-assisted screw placement, a post-procedure CT scan was obtained to evaluate actual screw placement against the pre-procedure plan. A custom-made image analysis program was devised to measure screw tip/tail offset and angular offset on axial and sagittal planes. Results: For different OFPs, the mean tip offset, tail offset and angular offsets were 1.6 ± 0.9 mm (Range 0.0–3.6 mm), 1.4 ± 0.4 mm (Range 0.3–2.5 mm) and 1.1 ± 0.4° (Range 0.5–2.1), respectively. Conclusion: In this feasibility study, surgeons were able to place screws into the clinically relevant fracture pathways of the pelvis using ExcelsiusGPS® for robotic-assisted surgery. The measured accuracy was encouraging; however, further investigation is needed to demonstrate that robotic-assisted surgery can be used to successfully place the screws in the bony corridors of the pelvis to treat traumatic pelvic injuries. [ABSTRACT FROM AUTHOR]

Purpose: The Focused Assessment with Sonography for Trauma (FAST) is a tool to rapidly detect intraabdominal and intrapericardial fluid with point-of-care ultrasound. Previous studies have questioned the role of FAST in patients with pelvic fractures. The aim of the present study was to assess the accuracy of FAST to detect clinically significant intraabdominal hemorrhage in patients with pelvic fractures. Methods: We included all consecutive patients with pelvic and/or acetabular fractures treated our Level 1 trauma center from 2009–2020. We registered patient and fracture characteristics, FAST investigations and CT descriptions, explorative laparotomy findings, and transfusion needs. We compared FAST to CT and laparotomy findings, and calculated true positive and negative findings, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Results: We included 389 patients. FAST had a sensitivity of 75%, a specificity of 98%, a PPV of 84%, and a NPV of 96% for clinically significant intraabdominal bleeding. Patients with retroperitoneal hematomas were at increased risk for laparotomy both because of True-negative FAST and False-positive FAST. Conclusion: FAST is accurate to identify clinically significant intraabdominal blood in patients with severe pelvic fractures and should be a standard asset in these patients. Retroperitoneal hematomas challenge the FAST interpretation and thus the decision making when applying FAST in patients with pelvic fractures. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the clinical prevalence, characteristics, and relevance of the corona mortis (CM) in anterior approaches to the pelvis and acetabulum. Methods: Retrospective analysis of 185 theater reports from patients (73 females; mean age 62.8 ± 17.2 years) who underwent surgeries for pelvic ring injuries, acetabular fractures, or combined injuries using anterior approaches (Modified Stoppa or Pararectus) at our institution between 01/2008 to 12/2022. During procedures, the CM was routinely identified, evaluated, and occluded. Bilateral exposure of the superior pubic branch in 25 cases led to 210 hemipelvises analyzed. Exclusions: CM not mentioned in report and revisions via the initial approach. Results: In the 210 hemipelvises examined, the prevalence of any CM vessel was 81% (170/210). Venous anastomoses were found in 76% of hemipelvises (159/210), arterial in 22% (47/210). Sole venous anastomoses appeared in 59% (123/210), sole arterial in 5% (11/210). Both types coexisted in 17% (36/210), while 19% (40/210) had none. A single incidental CM injury occurred without significant bleeding. In ten cases, trauma had preoperatively ruptured the CM, but bleeding was readily managed. Females had a significantly higher CM prevalence than males (p = 0.001). Conclusion: Our findings show a CM prevalence aligning more with anatomical studies than prior intraoperative series. Although we observed one incidental and ten trauma-related CM injuries, we did not encounter uncontrollable bleeding. Our data suggest that in anterior pelvic approaches, when the CM is actively identified and occluded, it is not associated with bleeding events, despite its high prevalence. [ABSTRACT FROM AUTHOR]

Postoperative surgical site infections remain a significant and prevalent complication after open reduction and internal fixation of acetabular fractures. Local antibiotics have been shown to decrease risk of postoperative infection, although recent evidence is conflicting. We provide a consistent and replicable technique for delivering intraoperative broad-spectrum antibiotics in the form of a putty applied directly to surgical implants. With this technique, systemic levels of those antibiotics remain safe and stable. [ABSTRACT FROM AUTHOR]

Periacetabular osteotomy includes a fluoroscopy-guided ischial cut without direct visualization. Previously described techniques include a mediolateral ischial cortex cut, which is associated with the risk of injuring nearby nerves. Another drawback of that technique is the difficulty connecting an ischial cortex cut with a retroacetabular cut due to orthogonal nature of the osteotomy. In general, an additional cut from medial to lateral is required. The present study aimed to describe a technique that eliminates those problems due to use of only a central cut of the ischium and the curved nature of the osteotomy. [ABSTRACT FROM AUTHOR]

Background: To achieve good bone fusion in anterior column reconstruction for vertebral fractures, not only bone mineral density (BMD) and bone metabolism markers but also lever arms due to bone bridging between vertebral bodies should be evaluated. However, until now, no lever arm index has been devised. Therefore, we believe that the maximum number of vertebral bodies that are bony and cross-linked with the contiguous adjacent vertebrae (maxVB) can be used as a measure for lever arms. The purpose of this study is to investigate the surgical outcomes of anterior column reconstruction for spinal fractures and to determine the effect of bone bridging between vertebral bodies on the rate of bone fusion using the maxVB as an indicator of the length of the lever arm. Methods: The clinical data of 81 patients who underwent anterior column reconstruction for spinal fracture between 2014 and 2022 were evaluated. The bone fusion rate, back pain score, between the maxVB = 0 and the maxVB ≥ 2 patients were adjusted for confounding factors (age, smoking history, diabetes mellitus history, BMD, osteoporosis drugs, surgical technique, number of fixed vertebrae, materials used for the anterior props, etc.) and analysed with multivariate or multiple regression analyses. The bone healing rate and incidence of postoperative back pain were compared among the three groups (maxVB = 0, 2 maxVB 8, maxVB ≧ 9) and divided by the maxVB after adjusting for confounding factors. Results: Patients with a maxVB ≥ 2 had a significantly higher bone fusion rate (p < 0.01) and postoperative back pain score (p < 0.01) than those with a maxVB = 0. Among the three groups, the bone fusion rate and back pain score were significantly higher in the 2 maxVB 8 group (p = 0.01, p < 0.01). Conclusions: Examination of the maxVB as an indicator of the use of a lever arm is beneficial for anterior column reconstruction for vertebral fractures. Patients with no intervertebral bone bridging or a high number of bone bridges are in more need of measures to promote bone fusion than patients with a moderate number of bone bridges are. [ABSTRACT FROM AUTHOR]

Background: To achieve good bone fusion in anterior column reconstruction for vertebral fractures, not only bone mineral density (BMD) and bone metabolism markers but also lever arms due to bone bridging between vertebral bodies should be evaluated. However, until now, no lever arm index has been devised. Therefore, we believe that the maximum number of vertebral bodies that are bony and cross-linked with the contiguous adjacent vertebrae (maxVB) can be used as a measure for lever arms. The purpose of this study is to investigate the surgical outcomes of anterior column reconstruction for spinal fractures and to determine the effect of bone bridging between vertebral bodies on the rate of bone fusion using the maxVB as an indicator of the length of the lever arm. Methods: The clinical data of 81 patients who underwent anterior column reconstruction for spinal fracture between 2014 and 2022 were evaluated. The bone fusion rate, back pain score, between the maxVB = 0 and the maxVB ≥ 2 patients were adjusted for confounding factors (age, smoking history, diabetes mellitus history, BMD, osteoporosis drugs, surgical technique, number of fixed vertebrae, materials used for the anterior props, etc.) and analysed with multivariate or multiple regression analyses. The bone healing rate and incidence of postoperative back pain were compared among the three groups (maxVB = 0, 2 maxVB 8, maxVB ≧ 9) and divided by the maxVB after adjusting for confounding factors. Results: Patients with a maxVB ≥ 2 had a significantly higher bone fusion rate (p < 0.01) and postoperative back pain score (p < 0.01) than those with a maxVB = 0. Among the three groups, the bone fusion rate and back pain score were significantly higher in the 2 maxVB 8 group (p = 0.01, p < 0.01). Conclusions: Examination of the maxVB as an indicator of the use of a lever arm is beneficial for anterior column reconstruction for vertebral fractures. Patients with no intervertebral bone bridging or a high number of bone bridges are in more need of measures to promote bone fusion than patients with a moderate number of bone bridges are. [ABSTRACT FROM AUTHOR]

Background: Accurate preoperative planning is crucial for successful total hip arthroplasty (THA) for developmental dysplasia of the hip (DDH). The aim of this study was to compare the accuracy of an artificial intelligence-assisted three-dimensional (3D) planning system (AIHIP) with two-dimensional templates in predicting acetabular cup size in THA for DDH. Method: This study retrospectively analyzed image data from 103 DDH patients who had THA between May 2019 and August 2023. AIHIP was used for 3D planning, and two-dimensional (2D) templates were used by two experienced surgeons. Accuracy was assessed by comparing predicted and actual cup sizes, and potential factors affecting accuracy were analyzed, including gender, side, BMI, and dysplasia classification. Results: AIHIP had higher accuracy in predicting the acetabular cup size compared to the 2D template. Within ± 0 size, AIHIP's accuracy was 84.1%, while the 2D template's was 64.0% (p < 0.05). Within ± 1 size, AIHIP's accuracy was 95.1%, while the 2D template's was 81.1% (p < 0.05). Accuracy was unaffected by gender, side, or BMI but was by DDH classification. In subgroup analysis, AIHIP's mean absolute error (0.21 ± 0.54) was significantly lower than the 2D template's (0.62 ± 0.95) for Crowe II and Crowe III (p < 0.05). Conclusion: AIHIP is superior to 2D templates in predicting the acetabular cup size accurately for THA in DDH patients. AIHIP may be especially beneficial for Crowe II and III DDH patients, as 2D templates may not accurately predict cup size in these cases. [ABSTRACT FROM AUTHOR]

The location of the lateral boundary of the necrotic lesion to the weight-bearing portion of the acetabulum (Type classification) is an important factor for collapse in osteonecrosis of the femoral head (ONFH). Recent studies also reported the significance of the location of the anterior boundary of the necrotic lesion on the occurrence of collapse. We aimed to assess the effects of the location of both anterior and lateral boundaries of the necrotic lesion on collapse progression in ONFH. We recruited 55 hips with post-collapse ONFH from 48 consecutive patients, who were conservatively followed for more than one year. Using a plain lateral radiograph (Sugioka's lateral view), the location of the anterior boundary of the necrotic lesion to the weight-bearing portion of the acetabulum was classified as follows: Anterior-area I (two hips) occupying the medial one-third or less; Anterior-area II (17 hips) occupying the medial two-thirds or less; and Anterior-area III (36 hips) occupying greater than the medial two-thirds. The amount of femoral head collapse was measured by biplane radiographs at the onset of hip pain and each follow-up period, and Kaplan–Meier survival curves with collapse progression (≥1 mm) as the endpoint were produced. The probability of collapse progression was also assessed by the combination of Anterior-area and Type classifications. Collapse progression was observed in 38 of the 55 hips (69.0%). The survival rate of hips with Anterior-area III/Type C2 was significantly lower. Among hips with Type B/C1, collapse progression occurred more frequently in hips with Anterior-area III (21 of 24 hips) than in hips with Anterior-area I/II (3 of 17 hips, P < 0.0001). Adding the location of the anterior boundary of the necrotic lesion to Type classification was useful to predict collapse progression especially in hips with Type B/C1. [ABSTRACT FROM AUTHOR]

Background: There are still many controversies regarding the diagnosis and management of developmental dysplasia of the hip (DDH). Axial imaging is routinely used after closed or open reduction to confirm reduction has occurred. In this study, we aimed to determine the rate of early re-dislocation or failure of reduction after anterior approach open reduction (AOR), to establish whether there is a true need for routinely performing post)operative axial imaging. Methods: We retrospectively reviewed radiographs, operation notes and post-operative CT scan images of our AOR cases from September 2018 to June 2020. The CT scan images were reviewed to check the post-operative reduction and congruency. The ‘posterior neckline’ and the ‘modified Shenton line’ were used to assess reduction. The related literature was also reviewed. Results: Thirty patients were included. The post-operative CT scans confirmed that all cases had reduced congruent hips. The CT scans did not change future treatment plans for any patient in this cohort and did not predict late redislocation. Conclusions: The rate of early re-dislocation or failure of reduction after AOR was negligible. Traditional routine axial imaging after this operation is therefore unjustified and has no value in predicting possible late re-dislocations. It also comes at the cost of extra radiation to the child and expense for the health system. We recommend stopping the routine use of post-operative axial imaging and using it selectively for specific indications, including teratologic and neuromuscular hips, bilateral DDH, and after revision surgery, in addition to closed reductions and medial approach open reduction. [ABSTRACT FROM AUTHOR]

Background: The hip joint is a ball and socket type of synovial joint comprising of head of femur and acetabulum of hip bone. Morphological variations of hip joint are noticed in different population resulting from racial, ethnic, and sexual differences. Present study was aimed to study acetabular depth, diameter and acetabular depth ratio of hip joint of south Indian population. Material and Methods: Present study was prospective, observational study, conducted 264 AP plain radiographs of normal hip joints (147 males and 117 females). The age group ranged from 20-90 years. All linear measurements including acetabular depth, acetabular diameter, Acetabular depth ratio & femoral head diameter were measured using Dicom viewer. Results: In the present study, acetabular depth (AD) was observed to be higher in males than in females, Higher mean acetabular diameter value was recorded on right side when compared to left side irrespective of gender. When the AD on the left side of males and females were compared, the difference in mean acetabular depth was found to be statistically significant (P<0.001). Higher mean acetabular diameter value was recorded on right side when compared to left side in both the genders. When comparison of Acetabular diameter was made between both genders irrespective of side, it was found that the value was highly significant (P<0.001). The mean value of Acetabular depth ratio (ADR) was found to be more in men than in women, showing a dysplastic tendency in the former. No statistical significance was found when ADR was compared between male right and left sides (p - 0.864) The mean value of ADR was found to be more in men than in women, showing a dysplastic tendency in the former. Conclusion: Values of acetabular depth, acetabular diameter, Acetabular depth ratio & femoral head diameter were more in men as compared to women, while laterality has no significant difference. [ABSTRACT FROM AUTHOR]

Purpose: To determine the added value of computed tomography (CT) to identify severe hip osteoarthritis (OA). Materials and methods: A retrospective query of all cases of hip or knee arthroplasty planning CTs between January 2018 and March 2022 was performed. Age, sex, and symptoms were collected from the medical record. CTs were evaluated for the degree of osteoarthritis and classified using an adapted Kellgren-Lawrence (KL) grading system in the anterior, posterior, superior, and superomedial hip. Frontal hip or pelvis radiographs within 1 year of the CT were also graded. Results: There were 265 eligible hips in 178 subjects, age 66 ± 11 (range 31–93) years, with 85/178 (48%) males and 93/178 (52%) females, and 127/265 (48%) right and 138/265 (52%) left hips. The posterior hip joint was the most common location for grade 2/3 OA (20%), followed by superior hip joint (14%). Anterior or posterior grade 2/3 OA occurred concurrently with superior or superomedial grade 2/3 OA in 32/68 (47%) of hips. Grade 2/3 OA was detected on CT more commonly than on XR both in the superior (14 vs 8.6%, P = 0.0016) and superomedial (8.7 vs 4.8%, P = 0.016) hip joint. Of the 71 symptomatic hips, 22 (31%) hips demonstrated either anterior and/or posterior grade 2/3 OA on CT, and 9 (9/22, 41%) of these hips had superior or superomedial grade 0/1 OA. Conclusion: CT may be warranted when the patient has pain suggestive of osteoarthritis not detected on radiographs. [ABSTRACT FROM AUTHOR]

Background: Developmental dysplasia of the hip (DDH) affects 1–3% of newborns and 20% of cases are bilateral. The optimal surgical management strategy for patients with bilateral DDH who fail bracing, closed reduction or present too late for these methods to be used is unclear. There are proponents of both medial approach open reduction (MAOR) and anterior approach open reduction (AOR); however, there is little evidence to inform this debate. Methods: We will perform a systematic review designed according to the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocol. We will search the medical and scientific databases including the grey and difficult to locate literature. The Medical Subject Headings "developmental dysplasia of the hip", "congenital dysplasia of the hip", "congenital hip dislocation", "developmental hip dislocation", and their abbreviations, "DDH" and "CDH" will be used, along with the qualifier "bilateral". Reviewers will independently screen records for inclusion and then independently extract data on study design, population characteristics, details of operative intervention and outcomes from the selected records. Data will be synthesised and a meta-analysis performed if possible. If not possible we will analyse data according to Systematic Review without Meta-Analysis guidance. All studies will be assessed for risk of bias. For each outcome measure a summary of findings will be presented in a table with the overall quality of the recommendation assessed using the Grading of Recommendations Assessment Development and Evaluation approach. Discussion: The decision to perform MAOR or AOR in patients with bilateral DDH who have failed conservative management is not well informed by the current literature. High-quality, comparative studies are exceptionally challenging to perform for this patient population and likely to be extremely uncommon. A systematic review provides the best opportunity to deliver the highest possible quality of evidence for bilateral DDH surgical management. Systematic review registration: The protocol has been registered in the International Prospective Register of Systematic Reviews (PROSPERO ID CRD42022362325). [ABSTRACT FROM AUTHOR]

Background: Traumatic hip dislocation is a rare yet severe injury. As the long-term morbidity, subsequent complications, and clinical outcomes are nearly unknown, we aimed to analyze traumatic hip dislocations and identify specific factors that may predict the clinical outcome. Methods: Data on injury-related characteristics and computed tomographic (CT) scans for all consecutive adult patients who had been managed for traumatic hip dislocation between 2009 and 2021 were analyzed. At the time of follow-up, the patients were assessed with regard to osteonecrosis, posttraumatic osteoarthritis (OA), further operations and complications, return to sports and work, and patient-reported outcome measures (PROMs), including the Tegner Activity Scale and modified Harris hip score. Results: One hundred and twelve patients (mean age [and standard deviation], 43.12 ± 16.6 years) were included. Associated acetabular rim and femoral head fractures (Pipkin Type I to IV) were observed in 44% and 40% of patients, respectively. Concomitant injuries occurred in 67% of the patients, most commonly involving the knee (29% of patients). Sixty-nine patients (61.6%) were available for follow-up; the mean duration of follow-up was 6.02 ± 3.76 years. The rates of osteonecrosis and posttraumatic OA were 13% and 31.9%, respectively, and were independent of the timing of hip reduction, leading to subsequent total hip arthroplasty (THA) in 19% of patients. Sciatic nerve injury occurred in 27.5% of the patients who were available for follow-up. Both THA and sciatic nerve injury were associated with posterior acetabular rim or Pipkin Type-IV fractures (p < 0.001). Only 33.3% of the patients returned to their pre-injury level of sports, 24.6% did not return to work, and 27.5% reported having sexual dysfunction. PROMs (Tegner Activity Scale, modified Harris hip score) were significantly worse in patients with osteonecrosis, posttraumatic OA, or residual sciatic nerve injury (p < 0.05). Conclusions: Traumatic hip dislocations are predominantly associated with Pipkin and acetabular rim fractures, leading to overall limitations of activities of daily living, sports, and sexual function at intermediate to long-term follow-up. Patients with associated acetabular rim or Pipkin Type-IV fractures are most likely to require THA for the treatment of osteonecrosis or posttraumatic OA and are at greater risk for sustaining sciatic nerve injury. Level of Evidence: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence. [ABSTRACT FROM AUTHOR]

To evaluate whether single acetabular column can be reserved and the effect of reconstruction with femoral head plus total hip replacement (THR) for primary malignant peri-acetabulum tumors. From 2007 to 2015, nineteen patients with primary malignant peri-acetabulum tumors were enrolled. All cases underwent single column resection with clear surgical margins. Ten of the 19 tumor's resections were assisted by computer navigation. Femoral heads were applied to reconstruct anterior or posterior column defects; THR was used for joint reconstruction. The surgical safety, oncologic outcome and prosthesis survivorship and function were evaluated by regular follow-up. The average follow-up period was 65.9 months. Surgical margins contained wide resection in 12 cases and marginal resection in 7 cases. One patient with Ewing's sarcoma died 14 months postoperative due to lung metastasis. One case with chondrosarcoma had recurrence. One prosthesis was removed due to infection. The average MusculoSkeletal Tumor Society (MSTS) function score was 83.7%. Due to the relative small number of cases, there was no significant difference in the recurrence rate and prosthesis failure rate between the navigation group and non-navigation group. Single column resection and reconstruction with femoral head autograft plus THR is an effective, safe method with less complication rate and better functional outcome for patients with peri-acetabular tumors. [ABSTRACT FROM AUTHOR]

Introduction: This study aimed to develop artificial intelligence models for predicting hip implant failure from radiological features. Analyzing the evolution of the periprosthetic bone and implant's position throughout the entire follow-up period has shown the potential to be more relevant in outcome prediction than simply considering the latest radiographic images. Thus, we investigated an AI-based model employing a small set of evolutional parameters derived from conventional radiological features to predict hip prosthesis failure. Materials and methods: One hundred sixty-nine radiological features were annotated from historical anteroposterior and lateral radiographs for 162 total hip arthroplasty patients, 32 of which later underwent implant failure. Linear regression on each patient's chronologically sorted radiological features was employed to derive 169 corresponding evolutional parameters per image. Three sets of machine learning predictors were developed: one employing the original features (standard model), one the evolutional ones (evolutional model), and the last their union (hybrid model). Each set included a model employing all the available features (full model) and a model employing the few most predictive ones according to Gini importance (minimal model). Results: The evolutional and hybrid predictors resulted highly effective (area under the ROC curve (AUC) of full models = 0.94), outperforming the standard one, whose AUC was only 0.82. The minimal hybrid model, employing just four features, three of which evolutional, scored an AUC of 0.95, proving even more accurate than the full one, exploiting 173 features. This tool could be shaped to be either highly specific (sensitivity: 80%, specificity: 98.6%) or highly sensitive (sensitivity: 90%, specificity: 92.4%). Conclusion: The proposed predictor may represent a highly sensitive screening tool for clinicians, capable to predict THA failure with an advance between a few months and more than a year through only four radiological parameters, considering either their value at the latest visit or their evolution through time. [ABSTRACT FROM AUTHOR]

Purpose: While the effects of tranexamic acid (TXA) use on transfusion rates after acetabular fracture surgery are unclear, previous evidence suggests that holding deep vein thrombosis (DVT) chemoprophylaxis may improve TXA efficacy. This study examines whether holding DVT chemoprophylaxis in patients receiving TXA affects intraoperative and postoperative transfusion rates in acetabular fracture surgery. Methods: We reviewed electronic medical records (EMR) of 305 patients who underwent open reduction and internal fixation of acetabular fractures (AO/OTA 62) and stratified patients per the following perioperative treatment: (1) no intraoperative TXA (noTXA), (2) intraoperative TXA and no preoperative DVT prophylaxis (opTXA/noDVTP), or (3) intraoperative TXA and preoperative DVT prophylaxis (opTXA/opDVTP). The primary outcomes were need for intraoperative or postoperative transfusion. Risk factors for each primary outcome were assessed using multivariable regression. Results: Intraoperative or postoperative transfusion rates did not significantly differ between opTXA/opDVTP and opTXA/noDVTP groups (46.2% vs. 36%, p = 0.463; 15.4% vs. 28%, p = 0.181). Median units transfused did not differ between groups (2 ± 1 vs. 2 ± 1, p = 0.515; 2 ± 1 vs. 2 ± 0, p = 0.099). There was no association between preoperative DVT chemoprophylaxis and TXA with intraoperative or postoperative transfusions. EBL, preoperative hematocrit, and IV fluids were associated with intraoperative transfusions; age and Charlson Comorbidity Index (CCI) were associated with postoperative transfusions. Conclusion: Our findings suggest holding DVT prophylaxis did not alter the effect of TXA on blood loss or need for transfusion. [ABSTRACT FROM AUTHOR]

Introduction: Unstable acetabular fracture remains a complex fracture that requires technically demanding surgery for orthopedic surgeons. Quadrilateral plate (QP) fractures of the acetabulum are a challenging group of acetabular fractures to manage. However, the literature regarding the management of these injuries are limited. The QP is a relatively thin medial wall of the acetabulum and intra-articular; thus, anatomical reduction and stable fixation are required for satisfactory outcome. This study aims to determine the functional, radiological, and quality of life outcome of unstable acetabular fracture with QP involvement. Methods: This was a retrospective cohort study conducted at Cipto Mangunkusumo General Hospital during the period of 2010–2020. Patients with unstable acetabular fractures with and without QP involvement were included in this study. They were followed up postoperatively at 1, 6, and 12 months. Functional outcome was assessed using the Harris Hip Score (HHS), Merle D'Aubigne, and Oxford Hip Score (OHS); while radiology outcome was assessed using Matta Outcome Grading; and quality of life was assessed using the SF-36. Results: This study involved 53 subjects with a median age was 29 (18–75) years of age. Twenty-eight (52.8%) subjects had unstable acetabular fracture with QP involvement. Twenty-five (47.2%) subjects had unstable acetabular fracture without QP involvement. Twenty-five (47.2%) subjects were fixed using quadrilateral hook plate, 3 (5.7%) with infrapectineal plate, 10 (18.8%) with posterior column plate, and 15 (28.3%) with suprapectineal plate. The median intraoperative bleeding in those with unstable acetabular fracture with QP involvement was 600 (300–4000) ml, which was higher than those without QP involvement (400 [100–1700] ml). Those with QP involvement achieved anatomical reduction in 20 (71.4%) subjects. Whereas, the subjects without QP involvement achieved anatomical reduction 23 patients (92%). Subjects with QP involvement had significantly lower functional, radiological, and quality of life outcomes compared to those without quadrilateral plate involvement based on Harris Hip Score (p = 0.046), Merle D'Aubigne (0.001), Oxford Hip Score (0.001), Matta Outcome Grading (0.004), and SF-36 (0.001). Patients with quadrilateral hook plate showed no significant functional, and radiological outcome difference compared to patients with infrapectineal plate based on Harris Hip Score (p = 0.582), Merle D'Aubigne (0.698), Oxford Hip Score (1.000), and Matta Outcome Grading (1.000). In addition, we also found no significant functional, radiological, and quality of life outcome difference between posterior column plate and suprapectineal plate group based on Harris Hip Score (p = 0.200), Merle D'Aubigne (0.643), Oxford Hip Score (0.316), Matta Outcome Grading (1.000), and SF-36 (0.600). Conclusions: Patients with unstable acetabular fracture with quadrilateral plate involvement subject had significantly lower functional, radiological, and quality of life outcomes compared to those without quadrilateral plate involvement. Both quadrilateral hook and infrapectineal plates demonstrated non-significant functional and radiological outcomes difference. Posterior column plate also resulted in the same functional, radiological, and quality of life outcome compared with suprapectineal fixation. [ABSTRACT FROM AUTHOR]

Background: Conversion total hip arthroplasty (THA) is considered the main treatment plan for patients with first-line treatment failure of acetabulum fracture. This meta-analysis aims to assess the effect of the type of initial treatment and timing of surgery on the outcomes of conversion THA. Methods: Using PRISMA guidelines, MEDLINE/PubMed, Scopus, Web of Science, and CENTRAL Cochrane were searched for articles published before October 14, 2022. Comparative studies investigating the outcome of THA following treatment failure of acetabular fracture were included. These articles were categorized into three groups, and the outcomes of treatment plans in each group were compared: (A) primary THA vs. conversion THA, (B) THA following conservative treatment vs. THA following ORIF, and (C) acute THA vs. delayed THA following prior treatment failure. Review Manager (RevMan, version 5.3) software was utilized to perform the statistical analysis. Results: Twenty-four comparative studies met the inclusion criteria (reported the data of 13,373 patients). Concerning group (A), the following complications were significantly higher in conversion THA: Infection (OR [95% CI] 3.19 [2.12, 4.79]; p value < 0.00001), dislocation (OR [95% CI] 4.58 [1.56, 13.45]; p value = 0.006), heterotopic ossification (OR [95% CI] 5.68 [3.46, 9.32]; p value < 0.00001), and Revision (OR [95% CI] 2.57 [1.65, 4.01]; p value < 0.00001). Postoperative HHS (SMD [95% CI] − 0.66 [− 1.24, − 0.08]; p value = 0.03) was significantly lower and operation time (SMD [95% CI] 0.88 [0.61, 1.15]; p value < 0.00001), blood loss (SMD [95% CI] 0.83 [0.56, 1.11]; p value < 0.00001), and bone graft need (OR [95% CI] 27.84 [11.80, 65.65]; p value < 0.00001) were significantly higher in conversion THA. Regarding group (B), bone graft need (OR [95% CI] 0.48 [0.27, 0.86]; p value = 0.01) was considerably higher in patients with prior acetabular fracture conservative treatment, while other outcomes were comparable. Respecting group (C), there were no significant differences in analyzed outcomes. However, systematically reviewing existing literature suggested a higher incidence rate of DVT following acute THA. Conclusion: There were significantly higher postoperative complications and lower functional outcomes in conversion THA compared to primary THA. While complications and functional outcomes were comparable between ORIF and the conservative groups, the bone graft need was significantly higher in the conservative group. There were no significant differences between aTHA and dTHA. These results can assist surgeons in designing treatment plans based on each patient's clinical situation. Prospero registration code: CRD42022385508. Level of evidence: III/IV. [ABSTRACT FROM AUTHOR]

Background: Minimally invasive surgical treatment of pelvic trauma requires a significant level of surgical training and technical expertise. Novel imaging and navigation technologies have always driven surgical technique, and with head-mounted displays being commercially available nowadays, the assessment of such Augmented Reality (AR) devices in a specific surgical setting is appropriate. Methods: In this ex-vivo feasibility study, an AR-based surgical navigation system was assessed in a specific clinical scenario with standard pelvic and acetabular screw pathways. The system has the following components: an optical-see-through Head Mounted Display, a specifically designed modular AR software, and surgical tool tracking using pose estimation with synthetic square markers. Results: The success rate for entry point navigation was 93.8%, the overall translational deviation of drill pathways was 3.99 ± 1.77 mm, and the overall rotational deviation of drill pathways was 4.3 ± 1.8°. There was no relevant theoretic screw perforation, as shown by 88.7% Grade 0–1 and 100% Grade 0–2 rating in our pelvic screw perforation score. Regarding screw length, 103 ± 8% of the planned pathway length could be realized successfully. Conclusion: The novel innovative system assessed in this experimental study provided proof-of-concept for the feasibility of percutaneous screw placement in the pelvis and, thus, could easily be adapted to a specific clinical scenario. The system showed comparable performance with other computer-aided solutions while providing specific advantages such as true 3D vision without intraoperative radiation; however, it needs further improvement and must still undergo regulatory body approval. Future endeavors include intraoperative registration and optimized tool tracking. [ABSTRACT FROM AUTHOR]

Purpose: Discrepancy between the morphology of the acetabular margin and the design of hemispheric acetabular cups used in total hip arthroplasty may produce postoperative hip pain due to an iliopsoas impingement at the iliopsoas notch. This study aimed to determine the anatomical features of the iliopsoas notch in the Central European sample, and to test whether the morphology of the proximal femur affects the size of the iliopsoas notch. Methods: The sample was composed of 40 matched pairs of dry hip bones and corresponding femora. The depth and length of the iliopsoas notch were measured and correlated with the available demographic data. The anthropometric parameters of the proximal femur were calculated using image-analysis software, and their association with the measurements of the iliopsoas notch was tested. Results: The iliopsoas notch was present in all specimens and featured four morphological configurations: curved (61.3%), angular (16.2%), irregular (16.2%), and straight (6.3%). Its size was found to be larger in males (P = 0.014 for depth, P < 0.001 for length). No significant difference existed between the sides. The height and age of the specimens did not correlate with the size of the iliopsoas notch. Furthermore, neither the femoral neck version, the lesser trochanteric version, nor the angle between the neck of the femur and the lesser trochanter influenced the dimensions of the iliopsoas notch. Conclusion: The iliopsoas notch is a consistent landmark of the acetabulum, although its anatomical appearance is widely variable. The iliopsoas notch arrangement cannot be predicted perioperatively based on the morphology of the proximal femur. The various shapes and sex-related differences detected in this study could be used for designing new hip implants or could be utilized during cup positioning in total hip arthroplasty. [ABSTRACT FROM AUTHOR]

Purpose: A "floating hip" (FH) injury is a rare injury describing the simultaneous ipsilateral fracture of the femur and pelvis or acetabulum (P/A). We describe our experience with patients presenting with FH injuries and compare them to controls with similar P/A fractures but without femoral involvement. Methods: Medical records and radiographs of FH patients and controls presenting to our tertiary centre between 2015 and 2020 were reviewed. Follow-up data from outpatient clinical records were also extracted. The control group were extensively matched by age, sex, body mass index, fracture classification and energy of injury. Results: From 1392 recorded P/A fractures, 42 FH cases were identified (average age 39 years, 78.6% males). The most common femoral fracture was the midshaft (35.7%), followed by the neck of femur (26.2%). 90.5% of FH injuries were due to high-energy mechanisms. 64.3% of P/A fractures, and 100% of femoral fractures were managed surgically. Compared to controls, FH cases were more likely to have additional orthopaedic injuries (73.8% vs. 40.5%, p = 0.002), more total theatre admissions (mean 2.5 vs. 1.19, p < 0.001), longer hospital stays (28.3 vs. 14.9 days, p = 0.02), and a higher rates of post-op complications (53.8% vs. 20%, p = 0.025) Conclusions: We report differences in the presentation, management, and outcomes of FH injuries versus controls, even after extensive matching for confounders. These differences may inform future treatment strategies for the FH injury. [ABSTRACT FROM AUTHOR]

Acetabular augmentation is a challenge for complex primary and revision hip surgery. Several methods exist to recreate a supportive, hemispherical acetabulum where a defect exists, however, these can be complex, expensive, time consuming, and limited by available size and shape. We present a simple, inexpensive, quick and customisable method of acetabular augmentation using cementless polyethylene with titanium coating. The first case is presented with follow-up up to 8 years. [ABSTRACT FROM AUTHOR]

Background: Early cup migration after total hip arthroplasty (THA) is correlated to late revision due to aseptic loosening. However, the use of screws for increased cup stability remains unclear and debated. The purpose of this study is to assess acetabular migration between cups fixated with and without the use of screws. Methods: Patients underwent primary THA using either a direct anterior (DA) or a direct lateral (DL) approach. The DA surgeon routinely supplemented cup fixation with 1 or 2 screws while the DL surgeon used no screws. At 7 follow-up visits up to 2 years post operation, patients underwent radiostereometric analysis (RSA) imaging for implant migration tracking. The primary outcome was defined as proximal cup migration measured with model-based RSA. Results: 68 patients were assessed up to 2 years post operation, n = 43 received screws and n = 25 did not. The use of screws had a significant effect on cup migration (p = 0.018). From 2 weeks to 2 years post operation, the total mean migration was 0.403 ± 0.681 mm and 0.129 ± 0.272 mm (p = 0.319) for cups with and without screws, respectively. The number of screws used also had a significant impact, with cups fixated with 1 screw migrating more than cups fixated with 2 (p = 0.013, mean difference 0.712 mm). Conclusions: Acetabular cups fixated with only 1 screw resulted in greater migration than cups with no screws or 2 screws, though the mean magnitude was well under the 1.0 mm threshold for unacceptable migration. However, 3 of the 24 patients who received only 1 screw exceeded the 1.0 mm threshold for unacceptable migration. Ultimately, the results of this study show that the use of 2 screws to supplement cup fixation can provide good implant stability that is equivalent to a secure press-fit component with no screws. Clinical trial registration: ClinicalTrials.gov (NCT03558217) [ABSTRACT FROM AUTHOR]

Purpose: Acetabular fracture fixation can be challenging, especially in the elderly. Open reduction and internal fixation (ORIF) alone may not allow for early weight bearing and is associated with a high rate of secondary osteoarthritis; therefore, a combined hip procedure (CHP) or ORIF with acute total hip arthroplasty, may be beneficial in this population. The objective of this study was to perform a systematic review of all reported cases of CHP. Methods: PubMed, Embase, Scopus, and Cochrane databases were searched for studies analyzing acetabular fractures in the elderly managed with a combined hip procedure (CHP). The research was performed following the PRISMA guidelines. The included studies' methodological quality was evaluated using the MINORS score. The present study was registered on PROSPERO. Results: Eleven clinical studies were included in the final analysis. The mean age was 74.4 (63.2–78) years. Low-energy trauma was the most common mechanism of injury (64%). The most prevalent fracture pattern was the anterior column and posterior hemitransverse (ACPHT) (30.6%). The Kocher-Langenbeck approach was preferred for ORIF of posterior fractures and hip arthroplasty. The ilioinguinal approach and modified Stoppa were generally used for anterior fractures. The overall complication rate was 12.2%, and hip dislocation was the most frequent cause of reoperation (4.4%). The average Harris Hip Score reported postoperatively was 81.6 points, which was considered "good." Conclusions: CHP is a safe treatment for elderly acetabular fractures with an acceptable complication and reoperation rate that results in good clinical outcomes. Level of evidence: Level of evidence IV. [ABSTRACT FROM AUTHOR]

Purpose: The complex anatomy of acetabular fracture needs a surgical approach that can achieve anatomical reduction with fewer complications for the fixation of these fractures. Current literature suggests that both Pararectus (PR) approach and Ilioinguinal (IL) approach can be used for the fixation of these fractures safely. However, superiority of the PR approach over the IL approach is not established. Hence, this meta-analysis aimed to compare the PR versus IL approach. Methodology: A literature search was performed on five databases Medline/PubMed, Scopus Embase, Cinhal, and Cochrane Library, from the inception to January 14, 2023. A qualitative and quantitative analysis was done for the five eligible studies from the literature search. Individual study characteristics data and outcomes were extracted, and Software version 5.4.1 of Review Manager was used for statistical analysis. Results: Five articles, one Randomized trial (RCT), and four retrospective articles were included and analyzed in this meta-analysis. PR approach has a shorter surgical time [mean difference (MD) −48.4 with 95% CI −74.49, −22.30; p = 0.0003], less intraoperative blood loss (MD −123.22 with 95% CI −212.28, −34.15; p = 0.007), and smaller surgical incision (MD −9.87 with 95% CI −15.21, −4.52; p = 0.0003) than the IL approach. However, the meta-analysis failed to show a difference between the two surgical approaches concerning the quality of reduction, overall complications, nerve injury, vascular injury, heterotopic ossification, deep vein thrombosis, and pulmonary embolism. Conclusion: The PR approach has a shorter surgical duration, less blood loss, and a smaller surgical incision than the IL approach. However, both surgical approaches have equivocal results regarding fracture reduction quality, complication rates, and functional outcomes for acetabular fracture fixation. Hence, for acetabular fractures fixation, PR approach can be considered a safe and feasible alternative to the IL approach. [ABSTRACT FROM AUTHOR]

Purpose: Proximal femoral osteotomy (PFO) with periacetabular osteotomy (PAO) improves femoral head coverage in patients with proximal femoral and acetabular dysplasia. Historically, blade plates used in the PFO cause soft-tissue irritation and often lead to implant removal. Here we present a technique using a lower profile pediatric proximal femoral locking compression plate (LCP) for the PFO in a series of adults. Methods: The results from 13 hips in 11 patients ≥ 18 years old (age 18–37) with > 10 months of follow-up are presented. Results: All patients had improved radiographic parameters, pain, and total Merle d'Aubigné–Postel scores postoperatively. Eleven hips (85%) had the LCP removed an average of 15.8 ± 8.6 months postoperatively, often due to pain over the greater trochanter. Conclusion: The pediatric proximal femoral LCP is effective for PFO in combined PAO PFO procedures but has a high rate of lateral hip discomfort leading to implant removal. [ABSTRACT FROM AUTHOR]

The idea that birds are maniraptoran theropod dinosaurs is now considered an evolutionary consensus. An "open" (i.e., completely or substantially perforate) acetabulum is considered an important synapomorphy verifying the bird–dinosaur nexus. Here, I present anatomical evidence from the acetabulum and its important appurtenances, the supracetabular crest and the antitrochanter, that hip anatomy differs substantially between dinosaurs and birds. Given the thin bone of the acetabular walls and the varied tissue, both hard and soft, in the acetabular region and especially the lower part of the basin, it is apparent that many avian skeletons exhibit some anatomical loss of soft tissue and thin bone, some perhaps related to changes in gait, but also in part related to the dramatic trend in bone reduction associated with flight, especially in more advanced crown taxa. Many basal birds and early diverging neornithines tend to have a nearly closed or partially closed acetabula, thus rendering the current terms "open" or "closed" acetabula inaccurate; they should be modified or replaced. Given new evidence presented here, the relationship of "dinosaurs" and birds must be re-evaluated. [ABSTRACT FROM AUTHOR]