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.

INTRODUCTION: 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. PATIENTS AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

The Association Between the Development of Cam Morphology During Skeletal Growth in High-Impact Athletes and the Presence of Cartilage Loss and Labral Damage in Adulthood: A Prospective Cohort Study With a 12-Year Follow-up.

BACKGROUND: Cam morphology develops during skeletal growth, but its influence on cartilage and the labrum in high-impact athletes later in life is unknown. PURPOSE: To (1) explore the association between the presence and duration of cam morphology during adolescence and the cartilage and labral status 7 to 12 years later and (2) report the prevalence of cartilage loss and labral damage in a population of young male athletes (<32 years old) who played professional soccer during skeletal growth. STUDY DESIGN: Cohort study (Prognosis); Level of evidence, 2. METHODS: A total of 89 healthy male academy soccer players from the Dutch soccer club Feyenoord (aged 12-19 years) were included at baseline. At baseline and 2.5- and 5-year follow-ups, standardized supine anteroposterior pelvis and frog-leg lateral radiographs of each hip were obtained. At 12-year follow-up, magnetic resonance imaging of both hips was performed. Cam morphology was defined by a validated alpha angle ≥60° on radiographs at baseline or 2.5- or 5-year follow-up when the growth plates were closed. Hips with the presence of cam morphology at baseline or at 2.5-year follow-up were classified as having a "longer duration" of cam morphology. Hips with cam morphology only present since 5-year follow-up were classified as having a "shorter duration" of cam morphology. At 12-year follow-up, cartilage loss and labral abnormalities were assessed semiquantitatively. Associations were estimated using logistic regression, adjusted for age and body mass index. RESULTS: Overall, 35 patients (70 hips) with a mean age of 28.0 ± 2.0 years and mean body mass index of 24.1 ± 1.8 participated at 12-year follow-up. Cam morphology was present in 56 of 70 hips (80%). The prevalence of cartilage loss was 52% in hips with cam morphology and 21% in hips without cam morphology (adjusted odds ratio, 4.52 [95% CI, 1.16-17.61]; P = .03). A labral abnormality was present in 77% of hips with cam morphology and in 64% of hips without cam morphology (adjusted odds ratio, 1.99 [95% CI, 0.59-6.73]; P = .27). The duration of cam morphology did not influence these associations. CONCLUSION: The development of cam morphology during skeletal growth was associated with future magnetic resonance imaging findings consistent with cartilage loss in young adults but not with labral abnormalities.

Femoroacetabular Impingement and Groin Injuries Among Soccer Players.

Groin injuries and femoroacetabular impingement are common among soccer players and can provide a challenge in diagnosis, as well as treatment. Nonoperative and operative measures are the 2 predominant treatments. This current review investigates the recent literature on groin and femoroacetabular impingement injuries in soccer players, as well as potential treatment modalities.

How to Best Identify Acetabular Retroversion on Radiographs: Thresholds to Guide Clinical Practice.

BACKGROUND: Acetabular retroversion is associated with impingement and instability. An adequate interpretation of acetabular version and coverage on radiographs is essential to determine the optimal treatment strategy (periacetabular osteotomy vs hip arthroscopic surgery). The crossover sign (COS) has been associated with the presence of acetabular retroversion, and the anterior wall index (AWI) and posterior wall index (PWI) assess anteroposterior acetabular coverage. However, the radiographic appearance of the acetabulum is sensitive to anterior inferior iliac spine (AIIS) morphology and pelvic tilt (PT), which differs between the supine and standing positions. PURPOSE: To (1) identify differences in the acetabular appearance between the supine and standing positions among patients presenting with hip pain; (2) determine factors (acetabular version, AIIS morphology, and spinopelvic characteristics) associated with the crossover ratio (COR), AWI, and PWI; and (3) define relevant clinical thresholds to guide management. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: Patients who presented to a hip preservation surgical unit (n = 134) were included (mean age, 35 ± 8 years; 58% female; mean body mass index, 27 ± 6). All participants underwent supine and standing anteroposterior pelvic radiography to assess the COS, COR, AWI, and PWI as well as standing lateral radiography to determine standing PT. Computed tomography was used to measure supine PT, acetabular version, and AIIS morphology. Acetabular version was measured at 3 transverse levels, corresponding to the 1-, 2-, and 3-o'clock positions. The correlation between radiographic characteristics (COR, AWI, and PWI) and acetabular version, AIIS morphology, and PT was calculated using the Spearman correlation coefficient. Receiver operating characteristic curve analysis was performed to define thresholds for the COR, AWI, and PWI to identify retroversion (version thresholds: <10°, <5°, and <0°). RESULTS: The COS was present in 55% of hips when supine and 30% when standing, with a mean difference in the COR of 12%. The supine COR (rho = -0.661) and AWI/PWI ratio (rho = -0.618) strongly correlated with acetabular version. The COS was more prevalent among patients with type 2 AIIS morphology (71%) than among those with type 1 AIIS morphology (43%) (P = .003). COR thresholds of 23% and 28% were able to identify acetabular version <5° (sensitivity = 81%; specificity = 80%) and <0° (sensitivity = 88%; specificity = 85%), respectively. An AWI/PWI ratio >0.6 was able to reliably identify acetabular version <0° (sensitivity = 83%; specificity = 84%). In the presence of a COR >30% and an AWI/PWI ratio >0.6, the specificity to detect retroversion was significantly increased (>90%). CONCLUSIONS: The presence of the COS was very common among patients with hip pain. False-positive results (high COR/normal version) may occur because of AIIS morphology/low PT. Relevant thresholds of COR >30% and AWI/PWI ratio >0.6 can help with diagnostic accuracy. In cases in which either the COR or AWI/PWI ratio is high, axial cross-sectional imaging can further help to avoid false-positive results.

Femoroacetabular impingement syndrome in middle-aged individuals is strongly associated with the development of hip osteoarthritis within 10-year follow-up: a prospective cohort study (CHECK).

OBJECTIVE: The objective is to determine the association and absolute risk of femoroacetabular impingement syndrome (FAIS) for the development of radiographic hip osteoarthritis (RHOA). METHODS: This is a nationwide, multicentre prospective cohort study (Cohort Hip and Cohort Knee) with 1002 individuals aged between 45 and 65 years. Hips without definitive RHOA (Kellgren-Lawrence (KL) grade≤1) at baseline and with anteroposterior pelvic radiographs at baseline and 10-year follow-up available (n=1386 hips) were included. FAIS was defined by the baseline presence of a painful hip, limited internal hip rotation≤25° and cam morphology defined by an alpha angle>60°. The outcomes were incident RHOA (KL grade≥2 or total hip replacement (THR)) and incident end-stage RHOA (KL≥3 or THR) within 10 years. RESULTS: Of the 1386 included hips (80% women; mean age 55.7±5.2 years), 21 hips fulfilled criteria for FAIS and 563 hips did not fulfil any of the FAIS criteria (reference group; no symptoms, no signs, no cam morphology). Within 10-year follow-up, 221 hips (38%) developed incident RHOA and 15 hips (3%) developed end-stage RHOA (including 9 hips with THR). Adjusted for sex, age and body mass index, FAIS with cam morphology resulted in an OR of 6.85 (95% CI 2.10 to 22.35) for incident RHOA and 47.82 (95% CI 12.51 to 182.76) for incident end-stage RHOA, compared with hips not having any FAIS criteria. The absolute risk of FAIS was 81% for incident RHOA and 33% for incident end-stage RHOA. CONCLUSION: FAIS was strongly associated with the development of RHOA within 10 years. Although the baseline prevalence of FAIS was low, the high absolute risk of FAIS for RHOA warrants further studies to determine preventive strategies.

Combined assessment of acetabular coverage and femoral head-neck shapes predicts osteoarthritis progression after periacetabular osteotomy.

INTRODUCTION: Postoperative osteoarthritis (OA) progression is a major determinant of failure after curved periacetabular osteotomy (CPO). A large postoperative combination angle, i.e., the combination of computed tomography-based anterior center edge and alpha angles, is associated with femoroacetabular impingement after CPO, but its association with postoperative OA progression is unclear. We aimed to identify the anatomical parameters that can lead to OA progression after CPO and the impact of the combination angle on the same. MATERIALS AND METHODS: We included 90 hips that were subjected to CPO at our center between March 2013 and March 2018. Seventeen hips showed OA progression with an increase in the Tönnis classification after surgery; 73 hips showed no progression. Radiographic anatomical parameters, including the lateral and anterior center edge angles, femoral and acetabular anteversion, and combination angle, and clinical outcomes, including modified Harris Hip Scores (mHHSs), postoperative anterior impingement, and range of motion, were compared between the two groups. Statistical significance was set at P < 0.05. RESULTS: Postoperative OA progression was significantly affected by preoperative OA evidence (P = 0.017), acetabular anteversion < 5.0° (P = 0.003), and a combination angle > 107.0° (P = 0.025). Patients with radiographic OA progression were associated with poor mHHSs (P = 0.017) and high frequencies of anterior impingement with a limited hip flexion and internal rotation angle. CONCLUSIONS: OA progression after CPO may be associated with preoperative evidence of OA and postoperative acetabular retroversion as well as a large combination angle. Surgeons should focus on the potential effects of preoperative OA grades, postoperative reduction in acetabular anteversion, and postoperative combination angle.

Increased combined anteversion is associated with larger posterior acetabular rim ossification in patients with femoroacetabular impingement syndrome.

PURPOSE: (1) To determine the prevalence, magnitude and distribution pattern of acetabular rim ossification in patients with femoroacetabular impingement syndrome (FAIS) and (2) to determine the association between acetabular rim ossification and rotational abnormalities of the hip. METHODS: Patients underwent hip arthroscopic surgery for FAIS at our institute between January 2021 and May 2022 were retrospectively reviewed. Patients were included if preoperative computed tomography (CT) images of the operated hip and ipsilateral distal femur were available for the measurement of femoral and acetabular anteversion. The presence and size of acetabular rim ossification were evaluated on coronal CT sections for the superior half of the acetabulum on each clockface location. The associations between acetabular rim ossification and radiographic parameters of hip rotational morphology were examined. RESULTS: A total of 214 hips were included. Acetabular rim ossification was found in 167 hips (78%) and the most common locations were 10 and 11 o'clock. Patients presenting with acetabular rim ossification had a mean size of 4.6 ± 1.6 mm. It was the largest at 9 o'clock position (4.9 ± 2.2 mm), with a decreasing trend in size from posterior to anterior. Logistics regression analysis found age was associated with the occurrence of posterior ossification (p = 0.002). Linear regression analysis found age (p = 0.049) and male sex (p < 0.001) were significantly correlated with the size of ossification. Patients with increased cranial combined anteversion had larger posterior ossification than patients with normal and decreased cranial combined anteversion (4.2 ± 2.9 vs. 3.1 ± 2.5 mm, p = 0.016; 4.2 ± 2.9 vs. 2.5 ± 2.4 mm, p = 0.005). CONCLUSION: Increased combined anteversion is associated with greater posterior acetabular rim ossification. The presence and size of acetabular rim ossification are positively associated with older age and male sex. LEVEL OF EVIDENCE: Level III.

How Is Variability in Femoral and Acetabular Version Associated With Presentation Among Young Adults With Hip Pain?

BACKGROUND: Acetabular and femoral version contribute to hip pain in patients with femoroacetabular impingement (FAI) or dysplasia. However, definitions and measurement methods of femoral version have varied in different studies, resulting in different "normal" values being used by clinicians for what should be the same anatomic measurement. This could result in discrepant or even inappropriate treatment recommendations. QUESTIONS/PURPOSES: In patients undergoing hip preservation surgery, (1) what is the range of acetabular and femoral version at presentation, and how much do two commonly used measurement techniques (those of Murphy and Reikerås) differ? (2) How are differences in acetabular and femoral version associated with clinical factors and outcomes scores at the time of presentation? METHODS: This was a retrospective analysis of data gathered in a longitudinally maintained database of patients undergoing hip preservation at a tertiary care referral center. Between June 2020 and December 2021, 282 hips in 258 patients were treated for an isolated labral tear (9% [26 hips]), hip dysplasia (21% [59 hips]), FAI (52% [147 hips]), mixed FAI and dysplasia (17% [47 hips]), or pediatric deformity (slipped capital femoral head epiphysis or Perthes disease; 1% [3 hips]) with hip arthroscopy (71% [200 hips]), periacetabular osteotomy (26% [74 hips]), surgical hip dislocation (2.5% [7 hips]), or femoral derotation osteotomy (0.5% [1 hip]). We considered those with complete radiographic data (CT including the pelvis and distal femur) and patient-reported outcome scores as potentially eligible. Exclusion criteria were age younger than 18 or older than 55 years (5 hips, 3 patients), signs of hip osteoarthritis (Tönnis grade ≥ 2; 0), pediatric deformity (slipped capital femoral head epiphysis or Perthes disease; 3 hips, 3 patients), previous femoral or acetabular osteotomy (2 hips, 2 patients), avascular necrosis of the femoral head (0), history of neuromuscular disorder (Ehlers-Danlos syndrome; 3 hips, 3 patients) or rheumatoid disease (ankylosing spondylitis; 1 hip, 1 patient), and when CT did not include the knees (19 hips, 19 patients). Based on these criteria, 249 hips in 227 patients were included. Of patients with bilateral symptomatic hips, one side was randomly selected for inclusion, leaving 227 hips in 227 patients for further analysis. The patients' median age (range) was 34 years (19 to 55 years), the median BMI (range) was 27 kg/m 2 (16 to 55 kg/m 2 ), and 63% (144) were female; they were treated with hip arthroscopy (in 74% [168]) or periacetabular osteotomy (in 23% [52]). Patients underwent a CT scan to measure acetabular version and femoral version using the Murphy (low < 10°; normal: 10° to 25°; high > 25°) or Reikerås (low < 5°; normal: 5° to 20°; high > 20°) technique. The McKibbin index was calculated (low: < 20°; normal: 20° to 50°; high > 50°). Based on the central acetabular version and femoral version as measured by Murphy, hips were grouped according to their rotational profile into four groups: unstable rotational profile: high (high acetabular version with high femoral version) or moderate (high acetabular version with normal femoral version or normal acetabular version with high femoral version); normal rotational profile (normal acetabular version with femoral version); compensatory rotational profile (low acetabular version with high femoral version or high acetabular version with low femoral version); and impingement rotational profile (low acetabular version with low femoral version): high (low acetabular version with low femoral version) or moderate (low acetabular version with normal femoral version or normal acetabular version with low femoral version). Radiographic assessments were manually performed on digitized images by two orthopaedic residents, and 25% of randomly selected measurements were repeated by the senior author, a fellowship-trained hip preservation and arthroplasty surgeon. Interobserver and intraobserver reliabilities were calculated using the correlation coefficient with a two-way mixed model, showing excellent agreement for Murphy technique measurements (intraclass correlation coefficient 0.908 [95% confidence interval 0.80 to 0.97]) and Reikerås technique measurements (ICC 0.938 [95% CI 0.81 to 0.97]). Patient-reported measures were recorded using the International Hip Outcome Tool (iHOT-33) (0 to 100; worse to best). RESULTS: The mean acetabular version was 18° ± 6°, and mean femoral version was 24° ± 12° using the Murphy technique and 12° ± 11° with the Reikerås method. Eighty percent (181 of 227) of hips had normal acetabular version, 42% (96 of 227) to 63% (142 to 227) had normal femoral version per Murphy and Reikerås, respectively, and 67% (152 to 227) had a normal McKibbin index. Patients with an impingement profile (low acetabular version or femoral version) were older (39 ± 9 years) than patients with an unstable (high acetabular version or femoral version; 33 ± 9 years; p = 0.004), normal (33 ± 9 years; p = 0.02), or compensatory (high acetabular version with low femoral version or vice versa; 33 ± 7 years; p = 0.08) rotational profile. Using the Murphy technique, femoral version was 12° greater than with the Reikerås method (R 2 0.85; p < 0.001). There were no differences in iHOT-33 score between different groups (impingement: 32 ± 17 versus normal 35 ± 21 versus compensated: 34 ± 20 versus unstable: 31 ± 17; p = 0.40). CONCLUSION: Variability in femoral version is twice as large as acetabular version. Patients with an impingement rotational profile were older than patients with a normal, compensatory, or unstable profile, indicating there are other variables not yet fully accounted for that lead to earlier pain and presentation in these groups. Important differences exist between measurement methods. This study shows that different measurement methods for femoral anteversion result in different numbers; if other authors compare their results to those of other studies, they should use equations such as the one suggested in this study. LEVEL OF EVIDENCE: Level III, prognostic study.

Radiological predictors of outcomes in hip arthroscopy for femoroacetabular impingement.

Aims: Hip arthroscopy has gained prominence as a primary surgical intervention for symptomatic femoroacetabular impingement (FAI). This study aimed to identify radiological features, and their combinations, that predict the outcome of hip arthroscopy for FAI. Methods: A prognostic cross-sectional cohort study was conducted involving patients from a single centre who underwent hip arthroscopy between January 2013 and April 2021. Radiological metrics measured on conventional radiographs and magnetic resonance arthrography were systematically assessed. The study analyzed the relationship between these metrics and complication rates, revision rates, and patient-reported outcomes. Results: Out of 810 identified hip arthroscopies, 359 hips were included in the study. Radiological risk factors associated with unsatisfactory outcomes after cam resection included a dysplastic posterior wall, Tönnis grade 2 or higher, and over-correction of the α angle. The presence of acetabular retroversion and dysplasia were also significant predictors for worse surgical outcomes. Notably, over-correction of both cam and pincer deformities resulted in poorer outcomes than under-correction. Conclusion: We recommend caution in performing hip arthroscopy in patients who have three positive acetabular retroversion signs. Acetabular dysplasia with a lateral centre-edge angle of less than 20° should not be treated with isolated hip arthroscopy. Acetabular rim-trimming should be avoided in patients with borderline dysplasia, and care should be taken to avoid over-correction of a cam deformity and/or pincer deformity.

Imaging Modalities in the Preoperative Assessment of Femoroacetabular Impingement and Hip Dysplasia: Determining Best Practices.

¼ In the last decade, significant progress has been made in understanding hip pain, especially related to femoroacetabular impingement (FAI) and hip dysplasia (HD), which collectively affect over 20% of the population.¼ Preoperative imaging, including plain radiographs, computed tomography (CT), magnetic resonance imaging (MRI), and ultrasound (US), plays a pivotal role in diagnosing FAI and HD. Imaging precision, standardized techniques, and accurate interpretation are crucial for effective treatment planning.¼ The continual advancements in imaging techniques, especially seen in MRI (arthrograms, application of leg traction, and delayed gadolinium-enhanced MRI of cartilage), represent important strides in the precise assessment of pathology associated with FAI and HD.¼ By incorporating these advancements into routine imaging protocols, healthcare providers can ensure a comprehensive understanding of hip joint dynamics, enabling more accurate diagnosis and effective management strategies for patients with FAI and HD, ultimately leading to improved clinical outcomes.

Imaging of Disease and Normal Variant Patterns in Pediatric Hips.

The pediatric hip undergoes significant changes from infancy through adolescence. Proper maturation is crucial for the development of a stable and functional hip joint. Imaging interpretation of the pediatric hip requires distinguishing normal variants and maturation patterns from pathology. We review femoral ossification centers, variants, and conditions that affect the proximal femur, such as Legg-Calvé-Perthes disease; the acetabulum, such as developmental hip dysplasia; the acetabular labrum, such as femoroacetabular impingement; and synovial pathology in children through adolescence. Understanding the spectrum of hip conditions and using advanced imaging techniques are essential for the accurate diagnosis and effective management of pediatric hip disorders.

Predictive Factors for Intraoperative Determination for the Need of Femoral Osteochondroplasty After Periacetabular Osteotomy for Acetabular Dysplasia.

Background: Determination of need for osteochondroplasty (OCP) during periacetabular osteotomy (PAO) commonly relies on intraoperative assessment of internal rotation at 90° flexion (IRF). Performing an OCP helps decrease the risk of iatrogenic femoroacetabular impingement from PAO reduction. Avoiding impingement helps decrease risks of accelerated secondary osteoarthritis. The literature is limited for factors that predict need for OCPs during PAOs. The purpose of this study was to (1) define the characteristics of patients needing concurrent OCP and provide OCP rate based on IRF and femoral version and (2) identify predictive factors (clinical, radiographic) associated with need for OCP during PAO. As some surgeons determine need for OCP pre-operatively, predictive factors would aid decision making. Methods: This was a prospective cohort of 224 hips (207 patients) who underwent PAO for symptomatic acetabular dysplasia, of which 154 hips (69%) underwent OCP between years 2013 and 2017. Patients underwent OCP if they had restrictions in motion or impingement intra-operatively. Pre-operative factors such as age, sex, BMI, and CT findings were recorded that underwent univariate and multivariable analyses. Multivariable analysis found predictors that were described using odds ratios and 95% confidence intervals. IRF>30° and femoral version 10°-25° were used as the reference groups during categorical analysis. P-values ≤0.05 were considered significant. Results: Alpha angles >55° (OR= 2.20, CI: 1.08-4.52, p= 0.03), IRF≤20° (OR: 9.52, CI: 3.87-23.40, p<0.001), IRF >20°-30° (OR: 2.68, CI: 1.08-6.62, p=0.03), and femoral version <10° (OR: 5.26, CI: 1.09-25.30, p=0.04) were associated with increased odds of OCP. On continuous modeling, decreasing femoral version (OR: 1.07, CI: 1.02-1.12, p=0.002) and IRF (OR: 1.06, CI: 1.03-1.09, p<0.001) were associated with increased chance of OCP. For 5° changes, the chance of OCP increased by 40% (OR: 1.40, CI: 1.13-1.73, p=0.002) and 35% (OR: 1.35, IC: 1.16-1.57, p<0.001), respectively. Conclusion: Awareness of need for OCP may be valuable in peri-operative planning for these patients especially since some surgeons perform this technique arthroscopically before PAO. Factors associated with increased chances of OCP were alpha angles >55°, decreased IRF, and decreased femoral version. More studies in the future would help determine how OCP affects patient outcomes. Level of Evidence: III.

Improving Patient Understanding of Femoroacetabular Impingement Syndrome With Three-Dimensional Models.

INTRODUCTION: Three-dimensional (3D) printed models may help patients understand complex anatomic pathologies such as femoroacetabular impingement syndrome (FAIS). We aimed to assess patient understanding and satisfaction when using 3D printed models compared with standard imaging modalities for discussion of FAIS diagnosis and surgical plan. METHODS: A consecutive series of 76 new patients with FAIS (37 patients in the 3D model cohort and 39 in the control cohort) from a single surgeon's clinic were educated using imaging and representative 3D printed models of FAI or imaging without models (control). Patients received a voluntary post-visit questionnaire that evaluated their understanding of the diagnosis, surgical plan, and visit satisfaction. RESULTS: Patients in the 3D model cohort reported a significantly higher mean understanding of FAIS (90.0 ± 11.5 versus 79.8 ± 14.9 out of 100; P = 0.001) and surgery (89.5 ± 11.6 versus 81.0 ± 14.5; P = 0.01) compared with the control cohort. Both groups reported high levels of satisfaction with the visit. CONCLUSION: In this study, the use of 3D printed models in clinic visits with patients with FAIS improved patients' perceived understanding of diagnosis and surgical treatment.

Effect of Spinopelvic Parameters on Outcomes After Hip Arthroscopy for Femoroacetabular Impingement Syndrome.

BACKGROUND: Spinopelvic parameters, including pelvic tilt (PT), sacral slope (SS), and pelvic incidence, have been developed to characterize the relationship between lumbar spine and hip motion, but a paucity of literature is available characterizing differences in spinopelvic parameters among patients with femoroacetabular impingement syndrome (FAIS) versus patients without FAIS, as well as the effect of these parameters on outcomes of arthroscopic treatment of FAIS. PURPOSE: To (1) identify differences in spinopelvic parameters between patients with FAIS versus controls without FAIS; (2) identify associations between spinopelvic parameters and preoperative patient-reported outcomes (PROs); and (3) identify differences in PROs between patients with stiff spines (standing-sitting ΔSS ≤10°) versus those without. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: The study enrolled patients ≥18 years of age who underwent primary hip arthroscopy for treatment of FAIS with cam, pincer, or mixed (cam and pincer) morphology. Participants underwent preoperative standing-sitting imaging with a low-dose 3-dimensional radiography system and were matched on age and body mass index (BMI) to controls without FAIS who also underwent EOS imaging. Spinopelvic parameters measured on EOS films were compared between the FAIS and control groups. Patients with FAIS completed the modified Harris Hip Score (mHHS) and Non-Arthritic Hip Score (NAHS) before surgery and at 1-year follow-up. Outcome scores were compared between patients with stiff spines versus those without. Associations between spinopelvic parameters and baseline outcome scores were assessed with Pearson correlations. Continuous variables were compared with Student t test and/or Mann-Whitney U test, and categorical variables were compared with Fisher exact test. RESULTS: A total of 50 patients with FAIS (26 men; 24 women; mean age, 36.1 ± 10.7 years; mean BMI, 25.6 ± 4.2) were matched to 30 controls without FAIS (13 men; 17 women; mean age, 36.6 ± 9.5 years; mean BMI, 26.7 ± 3.6). Age, sex, and BMI were not significantly different between the FAIS and control groups (P > .05). Standing PT was not significantly different between stiff and non-stiff cohorts (P = .73), but sitting PT in the FAIS group was more than double that of the control group (36.5° vs 15.0°; P < .001). Incidence of stiff spine was significantly higher in the FAIS group (62.0% vs 3.3%; P < .001). Among FAIS patients, those with stiff spines had a significantly higher prevalence of cam impingement, whereas those with non-stiff spines had a higher prevalence of mixed impingement (P = .04). No significant differences were seen in preoperative mHHS or NAHS scores or pre- to postoperative improvement in scores between FAIS patients with stiff spines versus those without (P > .05), but a greater sitting SS was found to be positively correlated with a higher baseline mHHS (r = 0.36; P = .02). CONCLUSION: Patients with FAIS were more likely to have a stiff spine (standing-sitting ΔSS ≤10°) compared with control participants without FAIS. FAIS patients with stiff spines were more likely to have isolated cam morphology than patient without stiff spines. Although sitting SS was positively correlated with baseline mHHS, no significant differences were seen in 1-year postoperative outcomes between FAIS patients with versus without stiff spine.

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

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

Femoroacetabular Variations Are Predisposing Factors for Traumatic Posterior Hip Dislocation.

BACKGROUND: 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. METHODS: 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. RESULTS: 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°. CONCLUSIONS: 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. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Mid-term results of autologous matrix-induced chondrogenesis for large chondral defects in hips with femoroacetabular impingement syndrome.

Aims: The purpose of this study was to evaluate the mid-term outcomes of autologous matrix-induced chondrogenesis (AMIC) for the treatment of larger cartilage lesions and deformity correction in hips suffering from symptomatic femoroacetabular impingement (FAI). Methods: This single-centre study focused on a cohort of 24 patients with cam- or pincer-type FAI, full-thickness femoral or acetabular chondral lesions, or osteochondral lesions ≥ 2 cm2, who underwent surgical hip dislocation for FAI correction in combination with AMIC between March 2009 and February 2016. Baseline data were retrospectively obtained from patient files. Mid-term outcomes were prospectively collected at a follow-up in 2020: cartilage repair tissue quality was evaluated by MRI using the Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score. Patient-reported outcome measures (PROMs) included the Oxford Hip Score (OHS) and Core Outcome Measure Index (COMI). Clinical examination included range of motion, impingement tests, and pain. Results: A total of 12 hips from 11 patients were included (ten males, one female, mean age 26.8 years (SD 5.0), mean follow-up 6.2 years (SD 5.2 months)). The mean postoperative MOCART score was 66.3 (SD 16.3). None of the patients required conversion to total hip arthroplasty. Two patients had anterior impingement. External hip rotation was moderately limited in four patients. There was a correlation between MOCART and follow-up time (rs = -0.61; p = 0.035), but not with initial cartilage damage, age, BMI, or imaging time delay before surgery. PROMs improved significantly: OHS from 37.4 to 42.7 (p = 0.014) and COMI from 4.1 to 1.6 (p = 0.025). There was no correlation between MOCART and PROMs. Conclusion: Based on the reported mid-term results, we consider AMIC as an encouraging treatment option for large cartilage lesions of the hip. Nonetheless, the clinical evidence of AMIC in FAI patients remains to be determined, ideally in the context of randomized controlled trials.

Computer-Assisted Arthroscopic Cam Resection.

Determining the appropriate femoral cam resection during hip arthroscopy for femoroacetabular impingement syndrome is both critical for the patient and challenging for the surgeon. Incomplete bone resection is a leading cause of failed hip arthroscopy, whereas over-resection may increase the risk of femoral neck fracture. The alpha angle is a validated 2-dimensional radiographic measurement used to both diagnose femoroacetabular impingement syndrome preoperatively and to determine resection adequacy postoperatively. Computer-assisted intraoperative guidance systems enhance the accuracy of femoral cam resection, although a preoperative 3-dimensional computed tomography scan may be required. Other systems, such as the HipCheck software (Stryker, Kalamazoo, MI), have been developed to provide intraoperative guidance with live feedback using simultaneous alpha angle measurements overlayed on fluoroscopic images without the requirement for routine preoperative computed tomography. Via intraoperative touchscreen navigation, the surgeon identifies the midpoint of the femoral neck and femoral head. A commercial software program provides real-time alpha angle measurements, as well as enhanced visualization of the femoral cam deformity with an adjustable resection curve. Before the surgeon performs the cam resection, the software provides a template for appropriate resection depth in 6 positions of the hip. Upon completion of the femoral cam resection, the hip is again assessed in the same 6 positions and the alpha angle is assessed to ensure a complete resection.

Modern Hip Arthroscopy for FAIS May Delay the Natural History of Osteoarthritis in 25% of Patients: A 12-Year Follow-up Analysis.

BACKGROUND: Little is known about the effect of modern hip arthroscopy on the natural history of femoroacetabular impingement syndrome (FAIS) with respect to joint preservation. PURPOSE: To (1) characterize the natural history of FAIS and (2) understand the effect of modern hip arthroscopy by radiographically comparing the hips of patients who underwent only unilateral primary hip arthroscopy with a minimum follow-up of 10 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Between 2010 and 2012, 619 consecutive patients were reviewed from the practice of a single fellowship-trained hip arthroscopic surgeon. Inclusion criteria were FAIS, bilateral radiographic findings of femoroacetabular impingement, primary unilateral hip arthroscopy (labral repair, femoroplasty, or capsular closure), and minimum 10-year follow-up. The preoperative and minimum 10-year postoperative radiographs of patients were evaluated at each time point. Both operative and nonoperative hips were graded using the Tönnis classification or the presence of hip arthroplasty by 2 independent reviewers. Subgroup analyses were performed. RESULTS: A total of 200 hips from 100 patients were evaluated at a mean follow-up of 12.0 years. Preoperatively, 98% and 99% of operative and nonoperative hips were evaluated as Tönnis grades 0 and 1, respectively; 5% of nonoperative hips had worse Tönnis grades than operative hips. The nonoperative hip advanced to a worse Tönnis grade in 48% (48/100) of cases compared with 28% (28/100) among operative hips. At follow-up, Tönnis grades between hips were equal in 70% (70/100) of the cases, the operative hip had a better grade 25% (25/100) of the time, and the nonoperative hip had a better grade 5% (5/100) of the time. Modern hip arthroscopy was associated with a relative risk reduction of 42% in osteoarthritis progression. Impingement with borderline dysplasia, age, preoperative Tönnis grade, and alpha angle >65° were key risk factors in the radiographic progression of osteoarthritis. CONCLUSION: Although the majority of patients (70%) undergoing hip arthroscopy for FAIS did not experience differences between operative and nonoperative hips in terms of the radiographic progression of osteoarthritis, the natural history may be favorably altered for 25% of patients whose Tönnis grade was better after undergoing arthroscopic correction. Modern hip arthroscopy indications and techniques represent a valid joint-preservation procedure conferring a relative risk reduction of 42% in the progression of osteoarthritis. Arthroscopy for mixed patterns of impingement and instability were the fastest to degenerate.