Posterior Hip Dislocation Research Articles

Practice Patterns Vary Widely in the Care of Pediatric and Adolescent Pelvic and Acetabular Fractures: A CORTICES Survey.

Pediatric pelvic and acetabular fractures are rare but potentially devastating injuries and significant management variation exists across the United States. This study sought to elucidate treatment decision-making trends, involvement of adult trauma fellowship-trained surgeons in pediatric care, and pre- and postoperative transfer patterns. Pediatric orthopaedic surgeons who serve as trauma liaisons at 20 PTCs were surveyed regarding training, practice volume, and factors contributing to institutional management of pelvic and acetabular injuries. Five clinical scenarios of pelvic ring and acetabular fractures that varied by injury pattern, age, and sex were presented. Descriptive statistics were used to summarize the results. Eighteen institutions responded to the survey (90% response rate, 16 Level, 1 PTC). All surgeons were pediatric fellowship-trained (77.7% in practice >5y). The four most common factors affecting whether surgeons independently managed both pelvic ring and acetabular fractures were patient age, fracture characteristics, displacement and need for surgery. The majority reported managing <10 acetabular (72.2%) but >10 pelvic ring (77.8%) injuries per year. In the clinical scenarios, patients <10 were more likely to have treatment decisions made by a pediatric orthopaedic surgeon. Older patients were more likely to be transferred to another institution for surgery but were often transferred back to the PTC postoperatively. In all clinical scenarios other than posterior hip dislocation, a trauma fellowship-trained surgeon was more likely to be the operative surgeon, even when the patient was not transferred. There is substantial variation in the management of pediatric and adolescent pelvic and acetabular fractures. Even at tertiary care PTCs, volumes are low, and trauma fellowship-trained surgeons are often involved in decision-making and operative management. Age and injury pattern seem to play a large role in variation, and patient transfers between facilities are common. V.

Traumatic native hip dislocation in the absence of acetabular or femoral fracture in adults: a retrospective study reporting clinical and radiological outcomes from a major trauma centre in the United Kingdom.

Posterior native hip dislocations (NHD) are high-energy injuries. Thompson-Epstein Type I dislocations describe those without significant associated femoral or acetabular fracture. The aim of this study was to compare the clinical and radiological outcomes of patients with Type I NHDs. We also evaluate the association between radiological indicators of femoroacetabular impingement (FAI) and NHD. A retrospective study from January 2012 to May 2021 compared skeletally mature patients (⩾16 years) with Type I posterior NHD to age and gender-matched controls with Type II-V posterior NHD. Patient demographics, mechanism of injury, complications and patient-reported outcome measures (PROMs) are presented. Post reduction radiographs and computed tomography were used to assess for FAI. Univariate analyses were performed to evaluate radiological outcomes. 13 patients (77% male) with Type I posterior NHD were compared to a control group of 40 patients (80% male) with Type II-V posterior NHD. 11 patients in the study group and 14 in the control group experienced isolated injuries (p = 0.01). Post-reduction complications were similar. The study group had significantly lower post-injury osteoarthritis incidence (n = 0) compared to controls (n = 18, p = 0.0083). Patients reported a mean Oxford Hip Score of 43.5 ± 2.2 and EQ-5D-VAS score of 87.1 ± 7.4, with 6 patients indicating minimal symptoms across all EQ-5D-5L domains. Radiological femoroacetabular impingement (FAI) was prevalent in both groups, especially among males. Patients who underwent emergent closed reduction of Type I NHD demonstrated good short to medium term outcomes. Our radiological findings suggest a high prevalence of FAI. Future work should aim to quantify longer term outcomes following this injury. We call for further comparative studies of patients who suffer NHD with and without fractures to aid our understanding of risk factors. Given the rarity of this injury, multicentre efforts will be required to capture large numbers of patients.

Posterior Labral Suture of Hip Joint by a 2-Step Camera Rotation Switching for Establishment of Bird’s-Eye View

Labral tear of the hip joint is an important factor causing joint pain and locking, as well as mobility disturbance. Although femoroacetabular impingement syndrome often results in anterior labral tears, posterior labral tears are present in a subset of patients, especially those with a history of posterior hip dislocation. Posterior labral repair under arthroscopy usually requires switching between the viewing approach and the operating approach, but this undoubtedly increases the operative time and the destruction of soft tissue. This article introduces a technique for rapid posterior labral suture by rotating the arthroscopic camera without switching the surgical approach.

Using an Intraoperative Stress Exam to Direct Treatment in Posterior Femoral Head Fracture-Dislocations.

To examine the results of a treatment algorithm incorporating an EUA performed intraoperatively after fixation of the femoral head through a Smith Petersen approach to determine need for posterior wall or capsule repair. Design: Retrospective review. Two Level 1 trauma centers. All acute, traumatic femoral head fractures from posterior hip dislocations treated at participating centers over a 5-year period from 2017-2022. Injuries were classified according to the Pipkin system. The primary outcome was the result of intraoperative EUA performed after femoral head fixation to determine the need for Kocher-Langenbeck exposure for posterior wall and/or capsule fixation. The secondary outcomes included rates of avascular necrosis, heterotopic bone formation, late instability, and conversion to total hip arthroplasty. Studied were 63 males and 22 females with mean age 32.5 (range 18-71). 79 of 85 (92.9%) patients had a stable EUA after fixation of the femoral head through a Smith-Petersen approach. Six (6/85, 7.1%) underwent an additional Kocher-Langenbeck approach for posterior wall or capsule fixation. This included 1 Pipkin I, 1 Pipkin II, and 4 Pipkin IV injuries. Of the Pipkin IV injuries, 51/55 (92.7%) had stable EUA and did not require fixation of their posterior wall. This included 7 patients with wall involvement >20%. Five patients were excluded because of planned fixation of their posterior wall based on preoperative imaging. Of patients with at least 6 months follow up, 16 of 65 (26.4%) developed radiographic evidence of AVN and 21 of 65 (32.3%) evidence of heterotopic bone formation. Seven out of 65 (10.8%) were converted to total hip arthroplasty over the study period. When comparing patients with a single exposure with those with additional KL exposure, they did not vary in their rate of AVN (27.1% vs. 0.0%, P=0.3228), HO formation (30.5% vs. 50.0%, P=0.3788), or conversion to total hip arthroplasty (10.2% vs. 16.7%, P=0.510). This study found residual posterior hip instability after femoral head fixation in patients with and without posterior wall fractures after posterior dislocations. The results of this study support use of an EUA after femoral head fixation to identify residual posterior hip instability in all femoral head fractures from posterior hip dislocations, regardless of Pipkin type. Use of the Smith-Petersen exposure remains a viable surgical option and may be improved with incorporation of an EUA after femoral head fixation. For Pipkin IV injuries with posterior wall fractures with indeterminate stability, an EUA accurately identifies residual instability. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Imaging evaluation of hip capsule disorders: a comprehensive review.

The hip capsule and capsular ligaments play crucial roles in providing hip stability and mobility. Their role in hip pathologies is being increasingly recognized, underscoring the need for thorough imaging evaluation, which is better performed through MRI-arthrography. Various diseases affect the hip capsule directly or indirectly. Improper mechanical loading, as seen in conditions such as femoroacetabular impingement or chondrolabral pathology, can induce capsule thickening, whereas thinning and laxity of the capsule are characteristics of microinstability. Inflammatory conditions, including adhesive capsulitis of the hip, crystal deposition disease, polymyalgia rheumatica, and infections, also lead to capsular changes. Traumatic events, particularly posterior hip dislocations, cause capsule ligament disruption and may lead to hip macroinstability. Friction syndromes can lead to capsular edema due to impingement of the adjacent capsule. Hip arthroscopy can result in various postoperative findings ranging from fibrotic adhesions to focal or extensive capsule discontinuation. Although the significance of hip capsule thickness and morphology in the pathogenesis of hip diseases remains unclear, radiologists must recognize capsule alterations on imaging evaluation. These insights can aid clinicians in accurately diagnosing and effectively managing patients with hip conditions.

Enhanced Surgical Techniques in Orthopedics: A Comprehensive Guide for Surgeons Based on Modification of the McFarland and Osborne Approach to the Hip.

The implementation of various approaches in hip arthroplasties introduces distinct advantages and complications. Notably, widely adopted methods such as the posterior approach have been linked to elevated rates of posterior hip dislocations and iatrogenic sciatic nerve injuries, while the lateral approach has been associated with superior gluteal nerve injuries. In this study, we propose a refined modification of the McFarland and Osborne approach, aiming to amalgamate the most favorable aspects of prior modifications of the lateral approach to the hip. Additionally, our contribution extends to providing a comprehensive stepwise guide for the exposure and closure processes in cases of bipolar hemiarthroplasty or total hip replacement. This modification not only offers potential advantages to seasoned orthopedic surgeons but also serves as a valuable resource for young Turks venturing into hip surgeries. 14 patients with femoral neck fractures underwent surgery using the modified McFarland and Osborne approach and were followed up for a period of six months. The functional outcome was analyzed by the Modified Mobility and Aids Scoring Matrix. Seven of the 14 patients attained pre-injury status with respect to the Mobility and Aids scoring matrix. six patients had a fall of 1, and one patient had a fall of 2, as compared to pre-injury status. Our research suggests that this method serves as a superior alternative to conventional approaches, demonstrating notable advantages in terms of dissection difficulty, reduced risk to neurovascular structures, and minimized post-operative hip dislocations. Additionally, it exhibits a favorable outcome, enabling a return to pre-injury levels of activity.

Combined Irreducible Femoral Head Fracture-Dislocation and Ipsilateral Segmental Femur Fracture: A Case Report.

A 48-year-old man presented to a Level 1 trauma center after a motor vehicle crash with a right irreducible posterior hip dislocation and ipsilateral fractures of the femoral head and segmental femur shaft. This injury was managed with open reduction and internal fixation and antegrade intramedullary nailing. This is the first report of a combined irreducible femoral head fracture-dislocation and a segmental femur fracture, a rare injury that requires a stepwise approach to operative management of each injury. Surgeons must recognize the clinical and radiographic findings associated with irreducible hip dislocations in the setting of ipsilateral fractures to the femoral head and shaft.

Bilateral Asymmetrical Hip Dislocations after Falling from Height: A Case Report and Literature Review

Background: Hip dislocations, constituting 2-5 percent of all joint dislocations, predominantly present as posterior dislocations. Bilateral hip dislocations are rare, accounting for 1.25% of cases. Associated fractures often involve the proximal femur and acetabulum. Case Report: A 60-year-old man with no prior hip trauma history sustained bilateral hip dislocations after a 6-meter fall. Initial assessments and a hip computed tomography (CT) scan confirmed posterior dislocation of the right hip and anterior dislocation of the left hip. The patient underwent a successful closed pelvic reduction operation four hours post-injury, as confirmed by a post-reduction CT scan. Conclusion: The study, encompassing 11 relevant studies and 208 patients, predominantly men (81%), revealed that asymmetrical bilateral hip dislocations were exceptionally rare (0.01-0.02 percent). Contrary to expectations, this study challenges the presumed stronger association of traffic accidents with bilateral dislocations, presenting a statistically significant association between the type of dislocation and trauma mechanism. Associated fractures, such as acetabulum fractures in unilateral cases and posterior edge fractures in bilateral cases, varied. Avascular necrosis (AVN), a common complication, was not observed in the current case, where reduction occurred within the critical 6-hour timeframe. This report contributes valuable insights into the characteristics and associations of asymmetric bilateral hip dislocations, emphasizing the importance of prompt intervention to mitigate complications. Further research is needed to validate these findings and explore underlying patterns in this rare clinical scenario.

Femoroacetabular Variations Are Predisposing Factors for Traumatic Posterior Hip Dislocation.

Although high-energy trauma mechanisms are generally considered to cause traumatic posterior hip dislocations, femoroacetabular variations are assumed to contribute to low-impact hip dislocations. Thus, the present study aimed to identify morphologic femoral and acetabular risk factors that may also contribute to posterior hip dislocations in high-energy trauma mechanisms. The acetabular and femoral morphology of 83 hips with a traumatic posterior dislocation following a high-energy trauma mechanism were analyzed and matched to a control group of 83 patients who sustained high-energy trauma without a hip injury. The lateral center-edge angle, acetabular index, acetabular depth/width ratio, cranial and central acetabular version angles, and the anterior and posterior acetabular sector angles were measured on computed tomography to quantify femoroacetabular impingement (FAI) morphology, acetabular version, and coverage. The caput-collum-diaphyseal angle and the alpha angles in the coronal and axial planes were measured to detect cam-type FAI deformity. A receiver operating characteristic curve was utilized to determine threshold values for an increased risk of hip dislocation. Acetabular retroversion and posterior acetabular undercoverage were significantly increased in patients with hip dislocations compared with controls (p < 0.001). The central acetabular version angle and posterior acetabular sector angle that indicated an increased risk of hip dislocation were ≤9° and ≤90°, respectively. Cam-type FAI deformity and coxa valga were significantly increased in the dislocation group (p < 0.001). The anterolateral alpha angle that indicated an increased dislocation risk was ≥47°. Acetabular retroversion, posterior acetabular undercoverage, and cam-type FAI morphology may be risk factors contributing to traumatic posterior hip dislocation in high-energy trauma mechanisms. Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Traumatic Posterior Hip Dislocation in a Child: When is an Anterior Open Reduction Indicated? A Case Report

Traumatic hip dislocations in children are uncommon, occurring in about 5% of all dislocations in children. Neglected hip dislocations are rarer and pose a serious threat to the normal development of the hip with complications of avascular necrosis and unstable gait. Open reduction is usually required, but the most appropriate surgical approach has not been clearly defined. We reported a child with a traumatic posterior hip dislocation who was successfully treated through an anterior approach after a previously failed posterior open reduction. An anterior open reduction of the hip following a previous failed posterior open reduction is a safe procedure and avoids the likelihood of an iatrogenic injury to the sciatic nerve. Pre-operative imaging with a CT scan or MRI is required in neglected cases to visualise intra-articular bone fragments, which can prevent a concentric reduction.

Acetabular "Fleck" Sign: Outcomes of Surgical Repair.

Traumatic, posterior hip dislocations in the pediatric population are typically managed by closed reduction to achieve a concentric hip joint. The presence of an acetabular "fleck" sign, despite concentric reduction, has been shown to signify significant hip pathology. The purpose of this study was to evaluate the outcomes of open labral repair through a surgical hip dislocation (SHD) in a consecutive series of patients with an acetabular "fleck" sign associated with a traumatic hip dislocation/subluxation. A retrospective review of patients between 2008 and 2022 who presented to a single, level 1 pediatric trauma center with a traumatic posterior hip dislocation/subluxation was performed. Patients were included if they had an acetabular "fleck" sign on advanced imaging and underwent open labral repair through SHD. Medical records were reviewed for sex, age, laterality, mechanism of injury (MOI), and associated orthopaedic injuries. The modified Harris hip score (mHHS) was utilized as the primary clinical outcomes measure. Patients were assessed for the presence of heterotopic ossification (HO) and complications, including implant issues, infection, avascular necrosis (AVN), and post-traumatic dysplasia. Twenty-nine patients (23 male, average age: 13.0±2.7 y; range: 5.2 to 17.3) were identified. Eighteen injuries were sports related, 9 caused by motor vehicle accidents, and 1 pedestrian struck. All patients were found to have an acetabular "fleck" sign on CT (26 patients) or MRI (5 patients). Associated injuries included: femoral head fracture (n=6), pelvic ring injury (n=3), ipsilateral femur fracture (n=2), and ipsilateral PCL avulsion (n=1). At the latest follow-up (2.2±1.4y), all patients had returned to preinjury activity/sport. Three patients developed asymptomatic, grade 1 HO in the greater trochanter region. There was no incidence of AVN. One patient developed post-traumatic acetabular dysplasia due to early triradiate closure. mHHS scores showed excellent outcomes (n=21, 94.9±7.4, range: 81 to 100.1). The acetabular "fleck" sign indicates a consistent pattern of osteochondral avulsion of the posterior/superior labrum. Restoring native hip anatomy and stability is likely to improve outcomes. SHD with open labral repair in these patients produces excellent clinical outcomes, with no reported cases of AVN. Level IV-therapeutic.

ARTICULAR FEMORAL HEAD FRACTURE MANAGEMENT: A COMPREHENSIVE SYSTEMATIC REVIEW

Background: Femoral head fractures (FHFs) are relatively rare injuries usually caused by high-energy trauma. They typically occur after a posterior dislocation, and approximately 5 to 15 of posterior hip dislocations involve FHFs. FHFs may also occur simultaneously with acetabular fractures, with an estimated incidence of 29.2 In addition, the incidence of ipsilateral femoral head and neck fractures (iFHNF) is low. However, iFHNFs, as a special type of fracture, have the worst prognosis among all FHFs The aim: The aim of this study to show about articular femoral head fracture management. Methods: By comparing itself to the standards set by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020, this study was able to show that it met all of the requirements. So, the experts were able to make sure that the study was as up-to-date as it was possible to be. For this search approach, publications that came out between 2014 and 2024 were taken into account. Several different online reference sources, like Pubmed and SagePub, were used to do this. It was decided not to take into account review pieces, works that had already been published, or works that were only half done. Result: In the PubMed database, the results of our search get 17 articles, whereas the results of our search on SagePub get 489 articles, on Google Scholar 8050 articles. Records remove before screening are 5860, so we get 2696 articles fos screening. After we screened based on record exclude, we compiled a total of 12 papers. We included five research that met the criteria. Conclusion: Open reduction and internal fixation of femoral head fracture using surgical hip dislocation through Ganz approach is a viable treatment option and provides satisfactory results with low complication rates.

An Atypical Presentation of Hip Dislocation In A Pregnant Patient: A Case Report and Review of the Literature

Managing an injured patient who is pregnant can be difficult in the management and investigation of the case especially when the patient presents atypically. We encountered a 25-year-old female patient who sustained a posterior dislocation of the right hip and was pregnant at 12 weeks gestation following a road traffic accident. The patient presented to OPD with an atypical attitude of limb i.e., both hip and knee in flexion without any internal rotation and adduction of the limb following which MRI was done which showed right hip posterior dislocation. Through an interdepartmental, skilful team approach the patient, after taking the obstetrician’s opinion and the patient under short GA, Closed reduction by Rochester method (longitudinal traction and rotation control) was done for the right hip joint without any complication. As pregnant females possess more risk and complication and more challenges are expected in management, Orthopaedic surgeons are well equipped to treat such patients to reduce patient morbidity and mortality resulting in better outcomes. Keywords Posterior dislocation of hip, Pregnant female, Atypical presentation, Closed reduction

Irreducible traumatic pure hip dislocation by the entrapment of the lateral rotator muscle group of the hip: A case report

Introduction: Irreducibility is a rare complication of pure posterior hip dislocation requiring surgical intervention. Case report: We present a case of a 22-year-old female with posterior hip dislocation following a motor vehicle accident. Despite unsuccessful closed reduction attempts, open surgical reduction successfully released the incarcerated muscles and achieved reduction. Follow-up examinations showed excellent functional outcomes without complications.

Insufficient stem antetorsion and lower cup abduction is a combined risk factor for posterior hip dislocation in patients undergoing THA for femoral neck fractures: a retrospective analysis

BackgroundThe role of acetabular and femoral component positions with respect to the risk of post-operative instability and dislocation remains debated. In this study, we aimed to identify potential risk factors for early dislocation following primary total hip arthroplasty (THA) for displaced intracapsular femoral neck fractures (FNF) using radiological measurements.MethodsWe retrospectively analyzed data for patients who underwent cementless primary THA for FNF using a posterolateral approach between January 2018 and December 2021. Follow-up duration, age, sex, affected side, and mean time from THA to dislocation were recorded. Leg-length inequality, abductor lever arm, vertical and horizontal femoral offsets, vertical and horizontal hip centers of rotation, abduction, anteversion of the acetabulum and femoral prosthesis, and combined anteversion were measured.ResultsThe study sample included 17 men and 34 women, with 21 and 30 patients undergoing left- and right-hip operations, respectively. The mean patient age was 70.18 ± 7.64 years, and the mean follow-up duration was 27.73 ± 13.52 months. The mean time between THA and dislocation was 1.58 ± 0.79 months. Seven patients (13.73%) sustained posterior dislocation of the hip. The abduction angle (36.05 ± 6.82° vs. 45.68 ± 8.78°) (p = 0.008) and anteversion of the femoral prosthesis (8.26 ± 4.47° vs. 19.47 ± 9.01°) (p = 0.002) were significantly lower in the dislocation group than in the control group. There were no significant differences in other parameters.ConclusionsInsufficient stem antetorsion combined with lower abduction angle of the acetabular component were associated with a high risk of dislocation, especially in patients with deep flexion or internal rotation of the flexed hip joint and knees, or in patients with a stiff spine or anterior pelvic tilt, impingement may then occur in the neck of the prosthesis and cup component, ultimately resulting in posterior dislocation. These findings could remind surgeons to avoid simultaneous occurrence of both in THA surgery. These results provide new insight into risk factors for hip dislocation in patients undergoing primary THA for FNF and may aid in reducing the risk of instability and dislocation.Level of evidenceProspective comparative study Level II.

An Unusual Combination of Subtrochanteric Fracture Associated with Ipsilateral Posterior Dislocation of Hip: A Case Report

Background: A unique fracture pattern involving subtrochanteric fracture associated with ipsilateral posterior dislocation of hip in a young adult male eventually having a functional hip at six year follow up following aggressive management is described. Case presentation: We present a case of a 40 year old male labourer from Central India who was admitted in our hospital within hours of a road accident he sustained in Feb 2012. Early reduction and osteosynthesis, supervised physiotherapy, and routine follow-up all contributed to the patient having an acceptable functioning hip at the six-year follow-up. Conclusion: The result at six year follow up showed complete union of fracture without any radiological signs of avascular necrosis of the femoral head which highlights the importance of team work in the management of the complex injury.

Comparative study of various anaesthetic blocks for optimal reduction of posterior hip dislocation

Native hip dislocations ideally should be reduced soon as possible To improve long-term outcomes. Avascular necrosis and post- traumatic osteoarthritis can be avoided with timely reduction and fixation of defects, if any. There is still debate on the sedation method and the context of the decrease. Allis outlined the standard procedure for the most frequent dislocation, the posterior dislocation: administering longitudinal tension with internal rotation to the hip. Innovative pain management techniques for patients who undergo planned Orthopedics surgery have received more attention recently. Anaesthesia blocks have been proven to be successful in managing acute trauma-related pain before surgical intervention. In this study, we assess the femoral block technique for the reduction of a posterior hip Dislocation and the post-operative results.

Functional outcome of a year-old neglected posterior hip dislocation after a 2-Stage operation: A case report

Functional outcome of a year-old neglected posterior hip dislocation after a 2-Stage operation: A case report

Direct Anatomic Registration in Computer-Assisted Total Hip Arthroplasty Improves Accuracy of Acetabular Cup Alignment.

Computer-assisted total hip arthroplasty using direct anatomic registration (DAR) with acetabular center axis software is an alternative method to the indirect anterior pelvic plane method. The software maps the center of hip rotation and orientation of the native acetabulum in 3 dimensions. This study aimed to evaluate the accuracy of acetabular cup alignment using DAR navigation combined with a mechanical guide device (MGD). This prospective nonrandomized controlled study included 106 patients who underwent primary cementless total hip arthroplasty through the posterolateral approach. Fifty-four patients in the study group underwent DAR combined with MGD, whereas 52 patients underwent MGD only for acetabular cup positioning. Plain radiographs of both hips and computerized tomographic scans were obtained 2 months postoperatively for the evaluation of acetabular cup inclination and anteversion, respectively. The acetabular cup alignment in the study group was within the Lewinnek safe zone more than that in the control group (81.5% vs 59.6%, P < .05). The study group had a mean inclination angle of 43.88° (standard deviation [SD] 5.38) and anteversion angle of 12.82° (SD 5.99), whereas the control group had 41.10° (SD 6.79) and 12.82° (SD 9.53), respectively. There were no significant differences in estimated blood loss, length of stay, and Harris hip scores at preoperative and 3 and 6 months postoperatively, except for the operative time, which was longer in the study group (P < .01). There was 1 posterior hip dislocation in each group. DAR navigation combined with MGD provides better accuracy for acetabular cup positioning within the Lewinnek safe zone compared with the conventional technique.

Patients with Simple Posterior Hip Dislocations Have Higher Rates of Hip Dysplasia and Borderline Dysplasia.

To determine if patients suffering simple, posterior hip dislocations are more likely to display dysplastic characteristics of their acetabulum as compared to those suffering fracture dislocations. Retrospective Cohort Study. Level 1 trauma center.Patients/Participants: 86 patients suffering posterior, native hip dislocations over a 5 year period. The primary outcome was measurement of the lateral center edge angle (LCEA), acetabular index (AI), acetabular version, and Femoro-Epiphyseal Acetabular Roof (FEAR) index. Eighteen (20.9%) patients sustained simple dislocations while 68 (79.1%) suffered fracture dislocations. Patients with simple dislocations had decreased LCEA (25.7 versus 34.3; P<0.001), increased AI (7.4 versus 5.8; P=0.019) and decreased acetabular anteversion (14.02 versus 18.45; P = 0.011). Additionally, patients with simple dislocations had higher rates of dysplasia and borderline dysplasia (61.1% versus 7.3%; P<0.001). Patients with fracture dislocations had higher rates of concomitant injuries (60.9% versus 29.4%; P=0.039) as well as higher injury severity scores (8.1 versus 12.3; P = 0.022). Patients who sustain simple hip dislocations are more likely to have under-coverage of the femoral head by the acetabulum as compared to patients suffering fracture dislocations. In addition, the simple dislocation group had a lower ISS and fewer concomitant injuries, which likely relates to a lower energy required for dislocation in the setting of lesser bony constraint. Surgeons treating these complicated injuries should consider measurements of LCE and AI when counseling patients on treatment strategies. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.