Mixed-type Femoroacetabular Impingement Research Articles

No Differences in Clinical Outcomes Between Hip Arthroscopy With Versus Without Capsular Closure in Patients With Cam- or Mixed-Type Femoroacetabular Impingement: A Randomized Controlled Trial

PurposeTo compare two-year clinical outcomes of primary hip arthroscopy with versus without capsular closure after interportal capsulotomy in patients with cam- or mixed- type femoroacetabular impingement (FAI). MethodsPatients with cam- or mixed-type FAI undergoing primary hip arthroscopy with interportal capsulotomy were prospectively enrolled in this randomised controlled trial (RCT) and allocated into either capsular closure or no capsular closure groups. Patients were blinded to group allocation. Clinical outcomes were assessed preoperatively and at 2 years follow-up using the International Hip Outcome Tool (iHOT-12), modified Harris Hip Score (mHHS), and six subsections of the Copenhagen Hip and Groin Outcome Score (HAGOS). Complications and reoperations were noted. ResultsEighty-four patients (100 hips) were enrolled, 49 hips in the capsular closure group and 51 in the no capsular closure group, with no significant differences in age (28.5±7.5 vs 30.4±8.4, p=0.261), BMI (23.5±3.0 vs 23.4±1.9, p=0.665), and sex distribution (F: 10.2% vs 13.7%, p=0.760). Four patients were lost to follow-up (2.0% vs 5.9%, p=0.618) and 6 had reoperations (6.1% vs 5.9%, p=1.000), which left 45 hips per group for clinical assessment. There were no significant differences between groups in the net change of iHOT-12 (28.3±19.6 vs 32.5±22.7, p=0.388), mHHS (7.6±13.1 vs 7.5±10.2, p=0.954), and subsections of HAGOS (p>0.05). Complication rates were also similar between groups (p>0.05). ConclusionThe present RCT compared primary hip arthroscopy with versus without capsular closure after interportal capsulotomy in a male-dominated, non-dysplastic, non-arthritic cohort with cam- or mixed- type FAI, and found no significant differences in patient-reported clinical outcomes, complication rates, or reoperation rates. Level of EvidenceLevel I, Randomised Controlled Trial

Clinical Outcomes After Arthroscopic Treatment of Extraspinal Diffuse Idiopathic Skeletal Hyperostosis (DISH) Involving the Hip Joint.

The hip joint can be affected by extraspinal diffuse idiopathic skeletal hyperostosis (DISH). This study aimed to compare the clinical characteristics of hips with DISH to those with mixed-type femoroacetabular impingement symptoms (FAIS). In addition, patient-reported outcome (PRO) scores were reported among patients with DISH involving the hip joint who underwent arthroscopic treatment. A retrospective analysis was performed using data from patients who underwent hip arthroscopy between 2017 and 2021. Patients who had a preoperative diagnosis of extraspinal DISH of the hip joint and postoperative Hip Outcome Score-Activities of Daily Living (HOS-ADL), Hip Outcome Score-Sports Subscale (HOS-SSS), International Hip Outcome Tool 12-component form (iHOT-12), modified Harris Hip Score (mHHS) and visual analog scale (VAS) for pain scores were enrolled in the study. The patients' characteristics were compared with those of a control group (1:2) consisting of mixed-type patients with FAIS. The control group was matched in terms of age, sex, body mass index (BMI), and symptom duration. Eleven hips (0.87%) with extraspinal DISH (study group) were matched to 22 FAIS hips (control group). All the patients were male. The mean age of patients was 42.0 ± 8.0 in the study group. The study group was characterized by a larger preoperative alpha angle (79.1 ± 6.8 vs 64.8 ± 9.7, P < .001), lateral center-edge angle (LCEA) (49.7 ± 6.0 vs 40.7 ± 3.2, P < .001), and postoperative LCEA (36.6 ± 3.0 vs 34.2 ± 2.0, P = .013). In addition, a higher proportion of acetabular (81.8% vs 31.8%, P = .007) and femoral head chondral lesions (45.5% vs 9.1%, P = .016). Cartilage damage has the potential to affect the prognosis of arthroscopic treatment. Nevertheless, at the final follow-up, patients with DISH experienced a significant increase in range of motion (ROM), notable enhancements in all PROs, and favorable rates of minimal clinically important difference (MCID) for the PROs. The occurrence of DISH in the hip joint is considerably infrequent, characterized by hip pain and limited ROM. Despite increased alpha angle and LCEA, and more acetabular and femoral head chondral damage noted at the time hip arthroscopy, patients with DISH observed a significant improvement in ROM, notable enhancements in all PROs, and favorable rates of MCID for the PROs.

Femoral impingement in maximal hip flexion is anterior-inferior distal to the cam deformity in femoroacetabular impingement patients with femoral retroversion

Femoroacetabular impingement (FAI) patients report exacerbation of hip pain in deep flexion. However, the exact impingement location in deep flexion is unknown. The aim was to investigate impingement-free maximal flexion, impingement location, and if cam deformity causes hip impingement in flexion in FAI patients. A retrospective study involving 24 patients (37 hips) with FAI and femoral retroversion (femoral version (FV) < 5° per Murphy method) was performed. All patients were symptomatic (mean age 28 years (SD 9)) and had anterior hip/groin pain and a positive anterior impingement test. Cam- and pincer-type subgroups were analyzed. Patients were compared to an asymptomatic control group (26 hips). All patients underwent pelvic CT scans to generate personalized CT-based 3D models and validated software for patient-specific impingement simulation (equidistant method). Mean impingement-free flexion of patients with mixed-type FAI (110° (SD 8°)) and patients with pincer-type FAI (112° (SD 8°)) was significantly (p < 0.001) lower compared to the control group (125° (SD 13°)). The frequency of extra-articular subspine impingement was significantly (p < 0.001) increased in patients with pincer-type FAI (57%) compared to cam-type FAI (22%) in 125° flexion. Bony impingement in maximal flexion was located anterior-inferior at femoral four and five o'clock position in patients with cam-type FAI (63% (10 of 16 hips) and 37% (6 of 10 hips)), and did not involve the cam deformity. The cam deformity did not cause impingement in maximal flexion. Femoral impingement in maximal flexion was located anterior-inferior distal to the cam deformity. This differs to previous studies, a finding which could be important for FAI patients in order to avoid exacerbation of hip pain in deep flexion (e.g. during squats) and for hip arthroscopy (hip-preservation surgery) for planning of bone resection. Hip impingement in flexion has implications for daily activities (e.g. putting on shoes), sports, and sex.Cite this article: Bone Joint Res2023;12(1):22-32.

Determining Clinically Meaningful Outcomes after Isolated Acetabuloplasty in the Context of Age and Arthritic Severity: A Retrospective Review of Prospectively Collected Data

AbstractOutcomes after isolated acetabuloplasty in mixed-type femoroacetabular impingement (FAI) patients can be favorable but are relatively unknown in the context of clinically important outcome variables (CIOVs) such as minimum clinically important difference and patient acceptable symptomatic state (PASS). Prognostic roles of age and osteoarthritis (OA) in hip arthroscopy are still unclear. We aimed to evaluate isolated acetabuloplasty outcomes including CIOVs while controlling for age and arthritis.This was a retrospective review of prospectively collected data. We analyzed patients with available 1-year follow-up for Patient-Reported Outcome Measurement Information System (PROMIS) scales for Physical Function (PF) and Pain Interference (PI). Patients were divided into two age groups (&lt; 40 years old vs. ≥ 40 years old) and two Outerbridge arthritis grade groups (grade 0–I vs. grade II–IV). Demographic, radiographic, and surgical characteristics as well as revision surgeries and complications were extracted. Our outcome was the proportion of patients that achieved values over literature-reported CIOV thresholds for PROMIS-PF and PROMIS-PI.A total of 63 patients of 96 eligible (65.6%) had minimum 1-year data. Characteristics were comparable between patients aged younger than 40 and 40 and over as well as between grade 0 to I and grade II to IV patients. Overall, average PROMIS-PF and PROMIS-PI scores improved. Approximately 81.0% of patients reached values over CIOV threshold (71.4% for PROMIS-PF, 54.0% for PROMIS-PI), with 44.4% reporting these outcomes for both PROMIS-PF and PROMIS-PI. Approximately 30.2% of patients reported values over PASS threshold for both PROMIS-PF and PROMIS-PI, with 25.4% of patients achieving values above all CIOV thresholds. Only one patient required revision surgery. When evaluating the effect of age while controlling for OA severity and vice versa, there were no significant outcome differences (p &gt; 0.615). When comparing patients reporting values above CIOV threshold versus those that did not, there were no differences in age (41.2 ± 13.0 [37.7, 44.8] vs. 45.9 ± 13.2 [38.4, 53.4], p = 0.265) or Outerbridge grade distribution (p = 0.177).This study uses CIOVs to describe clinically meaningful isolated acetabuloplasty outcomes for mixed-type FAI. Most patients over a wide spectrum of age and OA achieved favorable clinically meaningful outcomes following surgery. Isolated acetabuloplasty can alleviate symptomatology in mixed-type FAI patients on a case-by-case basis.

How frequent is absolute femoral retroversion in symptomatic patients with cam- and pincer-type femoroacetabular impingement?

AimsThe frequency of severe femoral retroversion is unclear in patients with femoroacetabular impingement (FAI). This study aimed to investigate mean femoral version (FV), the frequency of absolute femoral retroversion, and the combination of decreased FV and acetabular retroversion (AR) in symptomatic patients with FAI subtypes.MethodsA retrospective institutional review board-approved observational study was performed with 333 symptomatic patients (384 hips) with hip pain due to FAI evaluated for hip preservation surgery. Overall, 142 patients (165 hips) had cam-type FAI, while 118 patients (137 hips) had mixed-type FAI. The allocation to each subgroup was based on reference values calculated on anteroposterior radiographs. CT/MRI-based measurement of FV (Murphy method) and AV were retrospectively compared among five FAI subgroups. Frequency of decreased FV < 10°, severely decreased FV < 5°, and absolute femoral retroversion (FV < 0°) was analyzed.ResultsA significantly (p < 0.001) lower mean FV was found in patients with cam-type FAI (15° (SD 10°)), and in patients with mixed-type FAI (17° (SD 11°)) compared to severe over-coverage (20° (SD 12°). Frequency of decreased FV < 10° was significantly (p < 0.001) higher in patients with cam-type FAI (28%, 46 hips) and in patients with over-coverage (29%, 11 hips) compared to severe over-coverage (12%, 5 hips). Absolute femoral retroversion (FV < 0°) was found in 13% (5 hips) of patients with over-coverage, 6% (10 hips) of patients with cam-type FAI, and 5% (7 hips) of patients with mixed-type FAI. The frequency of decreased FV< 10° combined with acetabular retroversion (AV < 10°) was 6% (8 hips) in patients with mixed-type FAI and 5% (20 hips) in all FAI patients. Of patients with over-coverage, 11% (4 hips) had decreased FV < 10° combined with acetabular retroversion (AV < 10°).ConclusionPatients with cam-type FAI had a considerable proportion (28%) of decreased FV < 10° and 6% had absolute femoral retroversion (FV < 0°), even more for patients with pincer-type FAI due to over-coverage (29% and 13%). This could be important for patients evaluated for open hip preservation surgery or hip arthroscopy, and each patient requires careful personalized evaluation.Cite this article: Bone Jt Open 2022;3(7):557–565.

Combined abnormalities of femoral version and acetabular version and McKibbin Index in FAI patients evaluated for hip preservation surgery.

ABSTRACTFrequencies of combined abnormalities of femoral version (FV) and acetabular version (AV) and of abnormalities of the McKibbin index are unknown. To investigate the prevalence of combined abnormalities of FV and AV and of abnormalities of the McKibbin index in symptomatic patients with femoroacetabular impingement (FAI), a retrospective, Institutional Review Board (IRB)-approved study of 333 symptomatic patients (384 hips) that were presented with hip pain and FAI was performed. The computed tomography/magnetic resonance imaging based measurement of central AV, cranial AV and FV was compared among five subgroups with distinguished FAI subgroups and patients that underwent a hip preservation surgery. The allocation to each subgroup was based on AP radiographs. Normal AV and FV were 10–25°. The McKibbin index is the sum of central AV and FV. Of patients that underwent a hip preservation surgery, 73% had a normal McKibbin index (20–50°) but 27% had an abnormal McKibbin index. Of all patients, 72% had a normal McKibbin index, but 28% had abnormal McKibbin index. The prevalence of combined abnormalities of FV and AV varied among subgroups: a higher prevalence of decreased central AV combined with decreased FV of patients with acetabular-retroversion group (12%) and overcoverage (11%) was found compared with mixed-type FAI (5%). Normal AV combined with normal FV was present in 41% of patients with cam-type FAI and in 34% of patients with overcoverage. Patients that underwent a hip preservation surgery had normal mean FV (17 ± 11°), central AV (19 ± 7°), cranial AV (16 ± 10°) and McKibbin index (36 ± 14°). Frequency of combined abnormalities of AV and FV differs between subgroups of FAI patients. Aggravated and compensated McKibbin index was prevalent in FAI patients. This has implications for open hip preservation surgery (surgical hip dislocation or femoral derotation osteotomy) or hip arthroscopy or non-operative treatment.

Femoroacetabular impingement in the unpinned contralateral hip in patients with primary unilateral slipped capital femoral epiphysis: preliminary radiographic outcomes.

The study evaluated femoroacetabular impingement (FAI) in the unpinned contralateral hip in patients with unilateral slipped capital femoral epiphysis (SCFE) and verified initial age, posterior sloping angle (PSA) and center-edge angle (CEA) as predictors of FAI in the contralateral hip. 152 patients with unilateral SCFE with a mean index age of 13.2 years (8.2-17.2 years) were enrolled retrospectively into the study. Mean follow-up was 8 years (3-14 years). PSA and CEA were measured on initial radiographs of the unaffected hip. Alpha-angle and CEA were measured on radiographs taken at the last follow-up to identify FAI. Four groups of patients were distinguished: (1) no FAI (10 patients, 17.54%); (2) CAM-type FAI (41 patients, 71.9%); (3) pincer-type FAI (3 patients, 5.26%) and (4) mixed-type FAI (13 patients, 22.8%). The mean PSA was 12.1°, 12°, 16.8°, 11.9° for groups 1, 2, 3 and 4, respectively, with no significant difference ( P = 0.65). The mean initial CEA for groups 1, 2, 3 and 4 was 34.4°, 35.5°, 42° and 42° respectively, with significant differences between groups 1 versus 4 ( P = 0.034) and 2 versus 4 ( P = 0.009). Conclusions are as follows: 1. Radiographic features of FAI were present in 85.1% of unpinned contralateral hips in patients with unilateral SCFE. 2. 71.9% of unpinned contralateral hips developed CAM deformity. 3. CEA can be used in predicting pincer-type FAI in the contralateral hip in unilateral SCFE. 4. PSA and age revealed negligible value in predicting FAI.

Sex differences in the prevalence of radiographic findings of structural hip deformities in patients with symptomatic femoroacetabular impingement.

ABSTRACTThe purpose of this study was to determine the sex differences in the overall prevalence of radiographic femoroacetabular impingement (FAI) deformity patients presenting with hip pain and to identify the most common radiographic findings in male and female patients. A geographic database was used to identify patients between the age of 14 and 50 years with hip pain from 2000 to 2016. A chart and radiographic review was performed to identify patients with cam, pincer and mixed-type FAI. A total of 374 (449 hips) out of 612 (695 hips) male patients and 771 (922 hips) out of 1281 (1447 hips) female patients had radiographic features consistent with FAI. Ninety-four male hips (20.9%) and 45 female hips (4.9%) had cam type, 20 male hips (4.5%) and 225 female hips (24.4%) had pincer type and 335 male hips (74.6%) and 652 female hips (70.7%) had mixed type. The overall prevalence of radiographic findings consistent with FAI in male and female patients with hip pain was 61.1% and 60.2%, respectively. Mixed type was the most prevalent. The most common radiographic finding for cam-type FAI was an alpha angle >55°, and the most common radiographic finding for pincer-type FAI was a crossover sign. Male patients were found to have a higher prevalence of cam-type deformities, whereas female patients were found to have a higher prevalence of pincer-type deformities.

Acetabular Cartilage Thickness Differs Among Cam, Pincer, or Mixed-Type Femoroacetabular Impingement: A Descriptive Study Using In Vivo Ultrasonic Measurements During Surgical Hip Dislocation.

To investigate acetabular cartilage thickness among (1) 8 measurement locations on the lunate surface and (2) different types of femoroacetabular impingement (FAI). Prospective descriptive study comparing in vivo measured acetabular cartilage thickness using a validated ultrasonic device during surgical hip dislocation in 50 hips. Measurement locations included the anterior/posterior horn and 3 locations on each peripheral and central aspect of the acetabulum. The clock system was used for orientation. Thickness was compared among cam (11 hips), pincer (8 hips), and mixed-type (31 hips) of FAI. Mean age was 31 ± 8 (range, 18-49) years. Hips with no degenerative changes were included (Tönnis stage = 0). Acetabular cartilage thickness ranged from 1.7 mm to 2.7 mm and differed among the 8 locations (P < 0.001). Thicker cartilage was found on the peripheral aspect at 11 and 1 o'clock positions (mean of 2.4 mm and 2.7 mm, respectively). At 5 out of 8 locations of measurement (anterior and posterior horn, 1 o'clock peripheral, 12 and 2 o'clock central), cartilage thickness was thinner in hips with pincer impingement compared to cam and/or mixed-type of FAI (P ranging from <0.001 to 0.031). No difference in thickness existed between cam and mixed-type of impingement (P = 0.751). Acetabular cartilage thickness varied topographically and among FAI types. This study provides first baseline information about topographical cartilage thickness in FAI measured in vivo. Thinner cartilage thickness in pincer deformities could be misinterpreted as joint degeneration and could therefore have an impact on indication for hip preserving surgery.

Inter-observer concordance in normal and pathological findings of the hip joint in plain radiographs.

Background and aim:The purpose of the study was to compare the data obtained by two independent observers and statistically analyse the results using Cohen’s K to highlight the concordance or discordance in the diagnosis of normality, pathology and, in particular, the type of femoroacetabular impingement (FAI) on plain films.Methods:the study was conducted retrospectively. The only inclusion criterium was the minimum age of 20 years. All patients underwent a radiographic examination of the pelvis in standard anteroposterior projection in orthostasis.Results:A hundred patients were evaluated. A good concordance between the two operators in the examination of normal hip joint (k= 0.68 right/ 0,74 left) was found; a similar grade of agreement was found for the analysis of “pincer” type FAI (k = 0.73 right, 0,67 left). The best results in concordance were achieved in the examination of “cam” type FAI (k= 0.82 right, 0,88 left), “mixed” type FAI (k = 0.85 right, 0,86 left), and in findings of “coxa profunda” (k = 0.92 right, 0,88 left).Conclusion:We found a good concordance between the two readers; a few cases of disagreement were found in the diagnosis of “pincer” type FAI and absence of disease. This discrepancy may be due to the different weight given by the single observer to the clinical indication that leads the patient to examination, but also by the difficulty of a not dedicated radiologist to show some subtle signs indicative of early FAI.

FUNCTIONAL OUTCOMES OF ARTHROSCOPIC TREATMENT IN 230 FEMOROACETABULAR IMPINGEMENT CASES.

ABSTRACTObjective: To analyze the functional outcomes after arthroscopic treatment of femoroacetabular impingement (FAI). Methods: 194 patients (131 males and 63 females), with a mean age of 39 (15-68) years old for men and 43 (16-58) years old for women. The average follow-up was 17 months (2 to 71). 103 patients presented Cam-type FAI, 102 mixed and 25 Pincer. “Unilateral” arthroscopy was performed in 161 cases, “Bilateral” (only once each side) in 46 cases and, “Multiple” (more than one procedure on the same hip) in 23. The female sex was prevalent in the Pincer type FAI (76%), while males were prevalent in Mixed and Cam type, 74.5% and 72.8%, respectively. Results: The mean HHSpre score was 63.7 and 87.1 for HHSpost, i.e. 73.11%. Differences appeared between “mixed” and “unilateral” groups. The complications percentage in this series was 18.7% and 7% progressed to total hip arthroplasty. Conclusion: The arthroscopic FAI treatment improved the postoperative clinical scores of these patients, especially in cases of mixed-type FAI, which presented a higher improvement rate. Insufficient femoral osteoplasty was the main cause for surgical re-intervention, particularly in the initial cases of this series. Level of Evidence II, Retrospective study.

Population-based prevalence of femoroacetabular impingement in Japan

Objectives The prevalence of femoroacetabular impingement (FAI) was evaluated using a Japanese population-based cohort of participants aged ≥50 years. Methods Radiographs (n = 854) of bilateral hips of 427 participants (279 women, 148 men) were used for the analysis. The prevalence of cam type, pincer type, and mixed type FAI as well as osteoarthritis was evaluated. The association of FAI and osteoarthritis (OA), and pain were also evaluated. Results The prevalence of cam type and pincer type FAI were 4.2% and 20.3%, respectively. Mixed type FAI was 0.7%. OA was found in 4.0% of patients, and 17 hips (2.0%) with any FAI also had OA. A significant relationship between cam type FAI and OA was found, whereas no significant relationship between pincer type FAI and OA was seen. Sixty (7.0%) of all the hips were reported to be painful, and 14 of those painful hips (1.6%) had FAI. No significant relationship between FAI and hip pain was found. Conclusion We reported the first population-based prevalence of FAI in Japan. Radiological FAI was common, and pincer type was more common than cam type. The anatomical abnormalities associated with FAI, although often asymptomatic, are risk factors for OA.

Risk Factors for Long-term Hip Osteoarthritis in Patients With Femoroacetabular Impingement Without Surgical Intervention

Background: Femoroacetabular impingement (FAI) is a common cause of hip pain and a known risk factor for hip osteoarthritis (OA) and total hip arthroplasty (THA) at a young age. Unfortunately, little is known about the specific factors associated with an increased risk of OA. Purpose: To (1) report the overall rate of symptomatic hip OA and/or THA in patients with FAI without surgical intervention and (2) identify radiographic features and patient characteristics associated with hip OA. Study Design: Case-control study; Level of evidence, 3. Methods: A geographic database was used to identify all patients with hip pain and radiographs between 2000 and 2016. Chart review was performed to identify patients with FAI. Patient medical records were reviewed to obtain demographic information, clinical history, physical examination findings, imaging details, and treatment details. Kaplan-Meier analysis was used to determine the rate of hip OA. Univariate and multivariate proportional hazard regression models were performed to determine risk factors for OA. Results: The study included 952 patients (649 female; 303 male; 1104 total hips) with FAI. The majority of hips had mixed type (n = 785; 71.1%), 211 (19.1%) had pincer type, and 108 (9.8%) had cam type. Mean age at time of presentation was 27.6 ± 8.7 years. Mean follow-up time was 24.7 ± 12.5 years. The rate of OA was 13.5%. THA was performed in 4% of patients. Male sex, body mass index (BMI) greater than 29, and increased age were risk factors for OA (male sex: hazard ratio [HR], 2.28; P < .01; BMI >29: HR, 2.11; P < .01; per year of increased age: HR, 1.11; P < .01.). Smoking and diabetes mellitus were not significant risk factors. No radiographic morphological features were found to be significant risk factors for OA. Conclusion: At mean follow-up of 24.7 years, 14% of hips had symptomatic OA and 4% underwent THA. BMI greater than 29, male sex, and increased age at the time of presentation with hip pain were risk factors for hip OA. The cohort consisted of a large percentage of mixed-type FAI morphologies, and no specific radiographic risk factors for OA were identified.

Location of Intra- and Extra-articular Hip Impingement Is Different in Patients With Pincer-Type and Mixed-Type Femoroacetabular Impingement Due to Acetabular Retroversion or Protrusio Acetabuli on 3D CT–Based Impingement Simulation

Background: Diagnosis and surgical treatment of hips with different types of pincer femoroacetabular impingement (FAI), such as protrusio acetabuli and acetabular retroversion, remain controversial because actual 3-dimensional (3D) acetabular coverage and location of impingement cannot be studied via standard 2-dimensional imaging. It remains unclear whether pincer hips exhibit intra- or extra-articular FAI. Purpose: (1) To determine the 3D femoral head coverage in these subgroups of pincer FAI, (2) determine the impingement-free range of motion (ROM) through use of osseous models based on 3D-computed tomography (CT) scans, and (3) determine the osseous intra-and extra-articular 3D impingement zones by use of 3D impingement simulation. Study Design: Cross-sectional study; Level of evidence, 3. Methods: This is a retrospective, comparative, controlled study involving 70 hips in 50 patients. There were 24 patients (44 hips) with symptomatic pincer-type or mixed-type FAI and 26 patients (26 hips) with normal hips. Surface models based on 3D-CT scans were reconstructed and compared for hips with acetabular retroversion (30 hips), hips with protrusio acetabuli (14 hips), and normal asymptomatic hips (26 hips). Impingement-free ROM and location of impingement were determined for all hips through use of validated 3D collision detection software based on CT-based 3D models. No abnormal morphologic features of the anterior iliac inferior spine were detected. Results: (1) Mean total femoral head coverage was significantly (P < .001) increased in hips with protrusio acetabuli (92% ± 7%) and acetabular retroversion (71% ± 5%) compared with normal hips (66% ± 6%). (2) Mean flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (104°± 9°) and acetabular retroversion (116°± 6°) compared with normal hips (125°± 13°). Mean internal rotation in 90° of flexion was significantly (P < .001) decreased in hips with protrusio acetabuli (16°± 12°) compared with normal hips (35°± 13°). (3) The prevalence of extra-articular subspine impingement was significantly (P < .001) higher in hips with acetabular retroversion (87%) compared with hips with protrusio acetabuli (14%) and normal hips (0%) and was combined with intra-articular impingement. The location of anterior impingement differed significantly (P < .001) between hips with protrusio acetabuli and normal hips. Conclusion: Using CT-based 3D hip models, we found that hips with pincer-type and mixed-type FAI have significantly larger femoral head coverage and different osseous ROM and location of impingement compared with normal hips. Additionally, intra- and extra-articular subspine impingement was detected predominantly in hips with acetabular retroversion. Acetabular rim trimming during hip arthroscopy or open surgical hip dislocation should be performed with caution for these hips. Patient-specific analysis of location of impingement using 3D-CT could theoretically improve diagnosis and planning of surgical treatment.

The Prevalence of Radiographic Findings of Structural Hip Deformities for Femoroacetabular Impingement in Patients With Hip Pain

Background: Radiography is the initial imaging modality used to evaluate femoroacetabular impingement (FAI), and diagnostic radiographic findings are well-established. However, the prevalence of these radiographic findings in patients with hip pain is unknown. Purpose: The purpose was 3-fold: (1) to determine the overall prevalence of radiographic FAI deformities in young patients presenting with hip pain, (2) to identify the most common radiographic findings in patients with cam-type FAI, and (3) to identify the most common radiographic findings in patients with pincer-type FAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A geographic database was used to identify patients aged 14 to 50 years with hip pain between the years 2000 to 2016. The following were evaluated on radiographs: cam type: typical pistol grip deformity, alpha angle >55°; pincer type: crossover sign (COS), coxa profunda or protrusio acetabuli, lateral center edge angle (LCEA) ≥40°, Tönnis angle <0°; and mixed type: both cam- and pincer-type features. Posterior wall sign (PWS) and ischial spine sign (ISS) were also evaluated. The prevalence of each was determined. Descriptive statistics were performed on all radiographic variables. Results: There were 1893 patients evaluated, and 1145 patients (60.5%; 1371 hips; 374 male and 771 female; mean age, 28.8 ± 8.4 years) had radiographic findings consistent with FAI. Of these hips, 139 (10.1%) had cam type, 245 (17.9%) had pincer type, and 987 (72.0%) had mixed type. The prevalence of a pistol grip deformity and an alpha angle >55° was 577 (42.1%) and 1069 (78.0%), respectively. The mean alpha angle was 66.9°± 10.5°. The prevalence of pincer-type radiographic findings was the following: COS, 1062 (77.5%); coxa profunda, 844 (61.6%); ISS, 765 (55.8%); PWS, 764 (55.7%); Tönnis angle <0°, 312 (22.8%); LCEA ≥40°, 170 (12.4%); and protrusio acetabuli, 7 (0.5%). Conclusion: The overall prevalence of radiographic findings consistent with FAI in young patients with hip pain was 60.5%. Radiographic findings for mixed-type FAI were the most prevalent. The most common radiographic finding for cam-type FAI was an alpha angle >55°. The most common radiographic finding for pincer-type FAI was the COS.

Femoroacetabular Impingement Patients With Decreased Femoral Version Have Different Impingement Locations and Intra- and Extraarticular Anterior Subspine FAI on 3D-CT–Based Impingement Simulation: Implications for Hip Arthroscopy

Background: It remains unclear whether decreased femoral version (FV) causes anterior intra- or extra-articular femoroacetabular impingement (FAI). Therefore, we evaluated symptomatic hips with decreased FV, with and without cam and pincer FAI, by using computed tomography (CT)–based virtual 3-dimensional (3D) impingement simulation and compared this group with patients with normal FV and with asymptomatic hips. Purpose: To investigate (1) the osseous range of motion, (2) the osseous femoral and acetabular impingement zones, and (3) whether hip impingement is extra- or intra-articular in symptomatic hips with FAI. Study Design: Cross-sectional study; Level of evidence, 3. Methods: An institutional review board–approved, retrospective comparative analysis was performed on a total of 84 hips in 68 participants. Of these, 37 hips in 24 symptomatic patients with FAI had decreased FV. These hips were compared with 21 hips of 18 symptomatic patients with anterior FAI with normal FV (10°-25°) and 26 asymptomatic hips with no FAI and normal FV. All patients with FAI were symptomatic and had anterior hip pain and a positive anterior impingement test. They underwent pelvic CT scans to measure FV. Decreased FV was defined as FV less than 5°. The 37 hips with decreased FV presented both with and without cam and pincer FAI. All 84 hips were evaluated by use of CT-based 3D models and a validated 3D range of motion and impingement simulation. Asymptomatic hips were contralateral normal hips imaged in patients undergoing total hip arthroplasty. Results: Hips with FAI combined with decreased FV had a significantly (P < .001) lower mean flexion (114°± 8° vs 125°± 13°) and internal rotation (IR) at 90° of flexion (18°± 6° vs 32°± 9°, P < .001) compared with the asymptomatic control group. Symptomatic patients with FAI and normal FV had flexion of 120°± 16° and IR at 90° of flexion of 23°± 15°. In a subgroup analysis, we found a significantly (P < .001) lower IR in 90° of flexion in hips with FV less than 5° combined with mixed-type FAI compared with hips with FV less than 5° without a cam- or pincer-type deformity. The maximal acetabular impingement zone for hips with decreased FV was located at the 2-o’clock position and ranged from 1 to 3 o’clock. In hips with decreased FV, most of the impingement locations were intra-articular but 32% of hips had combined intra- and extra-articular FAI in internal rotation in 90° of flexion. During the flexion-adduction-IR test performed in 10° and 20° of adduction, extra-articular subspine FAI had significantly (P < .001) higher prevalence (68% and 84%) in hips with decreased FV compared with normal hips. Conclusion: Hips with FAI and decreased FV had less flexion and internal rotation in 90° of flexion compared with the asymptomatic control group. The majority of hip impingement due to low FV was intra-articular, but one-third of samples had combined intra- and extra-articular subspine FAI. Anterior extra- and intra-articular hip impingement can be present in patients who have FAI with decreased FV. This could be important for patients undergoing hip arthroscopy.

The Pattern of Acetabular Cartilage Wear Is Hip Morphology-dependent and Patient Demographic-dependent.

The Pattern of Acetabular Cartilage Wear Is Hip Morphology-dependent and Patient Demographic-dependent.

The clinical outcome of chondrolabral-preserving arthroscopic acetabuloplasty for pincer- or mixed-typefemoroacetabular impingement: A systematic review.

While preservation and repair of the acetabular labrum are increasingly being recognized as important goals in hip arthroscopy, controversies still exist regardingthe clinical outcome of arthroscopic acetabuloplasty with chondrolabral preservation. A systematic review was conducted and implemented by two independent reviewers, who used the MEDLINE/PubMed database and the Cochrane Database of Systematic Reviews for their search. These databases were queried with the terms "arthroscopic acetabuloplasty" and "chondrolabral preservation" and "arthroscopic acetabular recession." From the 55 initial studies the reviewers finally chose and assessed five clinical studies which were eligible to their inclusion-exclusion criteria. The reviewed studies included in total 444 patients, mainly young, between 30 and 40years old. The follow-up evaluation varied between 24 and 41months, while all studies utilized at least a 24-month final end-point assessment. All five studies illustrated improved outcome with the use of chondrolabral preservation acetabuloplasty without labral detachment. The rate of complications was very low. The different techniques of arthroscopic acetabuloplasty combined with chondrolabral preservation illustrated encouraging results in patients suffering from pincer-type or mixed-type FAI. However, the available clinical evidence was limited and insufficient to establish any superiority of these techniques over the traditional labral detachment and sequential reattachment. In relation to the optimal treatment of FAI without isolated CAM, further research of higher quality is recommended to be conducted in order to lead to definitive conclusions.

Pincer‐type MRI morphology seen in over a third of asymptomatic healthy volunteers without femoroacetabular impingement

In daily routine, pincer femoroacetabular impingement (FAI) findings are often seen without a clinical diagnosis of pincer FAI. To assess the presence of pincer FAI MRI findings in asymptomatic volunteers with negative impingement test versus patients with clinically confirmed FAI. Case-control study. Sixty-three asymptomatic volunteers and 63 matched patients with FAI were included. A coronal T1 -weighted turbo spin-echo sequence as well as a 3D oblique transverse water-excitation true fast imaging sequence at 1.5T. The volunteers underwent standard MRI of the hip, and patients underwent MR arthrography of the symptomatic hip using the same MR sequences. Measurements of cranial acetabular version, acetabular depth, and lateral center-edge angle were performed independently by three fellowship-trained musculoskeletal radiologists. Descriptive statistics, Mann-Whitney U-test, Unpaired t-test, receiver operating characteristics (ROC), Intraclass correlation coefficient (ICC). Forty-one percent (26/63, reader 1), 32% and 37% (20 and 23/63, reader 2/3) of asymptomatic volunteers had at least one positive MR finding for pincer-FAI. Patients with pincer or mixed-type FAI had cranial retroversion of the acetabulum of -0.2° ± 7.1 (mean ± standard deviation) for reader 1 and -0.3° ± 5.5/-0.2° ± 4.8 for reader 2 / reader 3, while asymptomatic volunteers had an anteversion of 6.2° ± 6.4 (reader 1) and 3.2° ± 4.9/3.1° ± 6.5 (readers 2/3): This difference was statistically significant (P ≤ 0.002), but there was a large overlap between the groups. Acetabular depth measurements were very similar for patients with either pincer or mixed-type FAI (5.1-5.3 mm ± 3.1) and volunteers (5.2-6.1 mm ± 2.6), without a statistically significant difference (P ≤ 0.50). Lateral center-edge angle was also similar in patients with either pincer or mixed-type FAI (32.1-35.1° ± 9.1) and volunteers (30.7-33.2° ± 6.5), without a statistically significant difference (P ≤ 0.28). There is a large overlap in pincer-type MRI findings between patients with symptomatic FAI and asymptomatic volunteers. More than a third of volunteers exhibited at least one positive pincer-type MRI finding. 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;49:1296-1303.

Hip morphology and patient factors associated with severity of hip symptoms in femoroacetabular impingement

Purpose: Femoroacetabular impingement (FAI) syndrome is a clinical disorder of the hip associated with pain and dysfunction, thought to be a precursor to hip osteoarthritis (OA). Several interacting anatomical parameters have been linked to the pathomechanism of FAI, including the alpha angle (αA), beta angle (βA), lateral centre edge angle (LCEA), acetabular version, femoral version, and femoral neck shaft angle (FNSA). Previous investigations of anatomical parameters and hip symptoms in FAI cohorts have primarily used plain radiographs, which permit only single-planar representation of the complex morphology of the femoral head and acetabulum, limiting analysis to the sub-region profiled. MRI provides multiplanar morphologic assessment without the use of ionizing radiation, with potential for post-processing of volumetric sequences to provide comprehensive, multi-planar consideration of αA, βA, femoral and acetabular version. We sought to study the relationship between symptom severity, morphological parameters and patient-level factors in FAI. Methods: Eighty-nine participants were diagnosed with FAI syndrome in a clinical setting by an orthopaedic surgeon. Age, gender, body mass index, nature of onset (gradual vs sudden) and duration of symptoms were recorded. Participants completed the international Hip Outcome Tool-33 (iHOT-33), a measure of hip health-related quality of life (QOL) (0 = worst possible QOL, 100 = best possible QOL), and the 10-point modified UCLA activity score (1 = “regular participation in impact sports”, 10 = “wholly inactive and dependent on others”). Participants received standardized plain radiographs and hip MRI scans on one of two 3T scanners (Siemens Prisma & Skyra). On a subset of 60 participant scans (41 cam-type, 3 pincer-type, 16 mixed-type FAI), αA was measured in four reconstructed radial planes at 30-degree intervals from superior to anterior (Fig. 1). The βA, defined as the angle formed by the αA vector and a line joining the centre of the femoral head to the acetabular rim, was also measured in these four planes. Femoral version was measured using axial hip and knee MRI sequences. Acetabular version was measured at 1cm inferior to the acetabular sourcil, using axial hip MRI sequences with the bi-ischial line as a reference point. LCEA and FNSA were measured on an AP pelvis X-ray. Statistical analyses included Pearson’s linear regressions and students' t-tests. Results: The 89 participants (32.9 ± 10.7 yrs, 40% female) had a mean iHOT-33 score of 41.0 ± 18.3. Modified UCLA activity scores and iHOT-33 scores were significantly associated (r = −0.351, P = 0.001), suggesting that more activity lends itself to better hip health-related QOL. Higher participant activity levels were also associated with a shorter duration of symptoms (r = 0.361, P = 0.001). No other patient factors were related to iHOT-33 score. The only anatomical parameter significantly associated with iHOT-33 score was the αA in the anterosuperior radial plane (r = −0.297, P = 0.025) (Table 1). Those with larger αAs (>75 degrees, n = 13) had significantly lower iHOT-33 scores than those with smaller αAs ( 75 degrees) and smaller αAs (<75 degrees) in any other radial plane, including for the maximum αA measured for each hip. Conclusions: Alpha angle in the anterosuperior radial plane was associated with hip health-related QOL, whereas other anatomical parameters, including αA measured in other radial planes, were not. Clinically, this finding supports the need for αA measurement at the anterosuperior radial plane in FAI diagnosis, and potentially highlights the importance of bony surgical correction at this region. Previous research has identified the anterosuperior region as particularly susceptible to chondrolabral damage in FAI; our study's findings link this structural damage to the presence of symptoms in FAI.