Pincer Femoroacetabular Impingement Research Articles

Reliability of Conventional Hip MRI in Detecting Labral Tear and Labrocartilagenous Lesions in cases of Femoroacetabular Impingement, A Comparative Study with Hip Arthroscopy.

Imaging studies play a crucial role in diagnosing femoroacetabular impingement (FAI), including plain radiography and Magnetic Resonance Imaging (MRI). FAI is a combined pathology of bony abnormality, labral and labrocartilagenous erosions. Surgical treatment for such cases has become more established and preoperative imaging is the roadmap that includes the assessment of labrum and articular cartilage. During a period of 2 years, thirty-seven patients with a clinical diagnosis of FAI were retrospectively enrolled in this study, including 17 men and 20 women, aged 27-62 years. There were 22 right hips and 15 left hips. MRI was done for all patients to identify bony details, labral and chondral abnormalities and to exclude coexisting disorders. The imaging findings were compared with the arthroscopic data. 15 patients had Pincer FAI, 11 patients had CAM, and 11 patients had combined Cam/Pincer FAI. Labral tear was detected in 100 % of patients, 97 % had an anterosuperior labral tear. 82 % of patients had partial thickness cartilage lesions and 8 % had full thickness cartilage lesions. MRI had a sensitivity of 100 % compared to hip arthroscopy in detecting labral tear, 60 % in detecting cartilage erosion. Conventional hip MRI detects bony changes in FAI, type of impingement and associated labral tear and cartilage erosions in comparison to the hip arthroscopy.

Acetabular Rim Ossification Variants Are Found in Almost 20% of Patients Presenting With Hip Pain

To determine the prevalence of 4 different types of acetabular rim ossifications, including partial labral ossification or punctate calcification, true os acetabuli, acetabular rim stress fracture, and complete labral ossification, and to determine whether different types of periacetabular ossifications are linked to demographic or radiological factors. We retrospectively reviewed the medial records of patients presenting for hip-related complaints at 2 sports medicine practices from September 2007 to December 2009. An anteroposterior radiograph of both hips and a lateral radiograph of each hip was obtained for all patients and reviewed for findings of cam and pincer femoroacetabular impingement, degenerative changes (Tönnis grade), and periacetabular calcifications for both hips. These parameters were also evaluated with respect to symptoms, sex, and age. Four hundred ninety-one consecutive patients (982 hips) presented to 2 orthopaedic surgeons at 2 centers for "hip"-related complaints. There were 223 males and 268 females (age 39 ± 14 years). The overall prevalence of periacetabular calcifications in hips was 17.6%, with 56.6% of calcifications in the symptomatic hip and 43.4% in the contralateral hip. Four basic patterns of calcification were identified: punctuate calcifications within the labrum (8.0% hips), large rounded calcifications (os acetabuli) (4.2% hip), large fragments with a vertical line of the superior-lateral acetabular rim, consistent with healed or non-healed stress fracture (2.0% hips), and complete ossification of the labrum (3.4% hips). Overall, male sex (P= .002), increased lateral center-edge angle (P= .046), and higher Tönnis grade (P < .001) statistically predicted the presence of periacetabular ossification. Punctate calcifications were more prevalent in males (P= .002). Higher Tönnis grade (P=.029) and increased alpha angle (P= .046) were more prevalent with os acetabuli. Younger age (P= .001), male sex (P= .048), increased alpha angle (P= .012), and increased lateral center-edge angle (P < .001) were more prevalent in acetabular rim fractures. No factors were statistically significant at predicting the presence of an ossified labrum. Periacetabular calcifications are not uncommon. Four particular patterns of calcification are identified: punctate labral calcifications (8%), larger rounded calcifications (i.e., os acetabuli) (4.2%), acetabular rim stress fractures (2%), and complete ossification of the labrum (3.4%) for a combined prevalence of 17.6% in patients presenting to an orthopaedic surgeon with "hip"-related complaints. Nearly half were in the asymptomatic hip. Male sex had a higher prevalence of periacetabular calcifications. An increased lateral center edge angle and higher Tönnis grade also had a higher prevalence of periacetabular calcifications. Younger male patients are more likely to have acetabular rim stress fractures. Patients with an increased alpha angle have a higher prevalence of os acetabuli and rim stress fractures. This study aims to identify, quantify, and categorize periacetabular calcifications about the hip. Their clinical relationships and relevance have been discussed, but no study has distinctly categorized the various types and their prevalence. This study provides a framework for identification and categorization.

Relationship between the Depth of Acetabuloplasty and Outcomes of Hip Arthroscopy in Patients with Global Pincer Femoroacetabular Impingement: Study with a Minimum Follow‐Up Period of 2 Years

There has been no definite consensus on the ideal depth of acetabuloplasty, especially in cases of global pincer femoroacetabular impingement (FAI). This study aims to determine whether the depth of acetabuloplasty influences postoperative outcomes in cases of global pincer FAI. Data were retrospectively collected from patients with global pincer FAI who underwent hip arthroscopy with a minimum follow-up period of 2 years from May 2014 to December 2018. Patients with global pincer FAI were subdivided into low or high resection depth groups based on whether the intraoperative acetabular rim was resected by more than 3 mm. Radiographic measurements; arthroscopic procedures; preoperative and postoperative PROs were recorded. Achievement of MCID and PASS was compared for the VAS, mHHS, HOS-ADL, and iHOT-12. A paired Student t-test was used to evaluate the significance of preoperative and postoperative PROs and two-tailed unpaired Student t-test was used to compare demographic data and PROs between different groups. MCID and PASS were evaluated using the chi-square test or the Fisher's exact test. A total of 41 hips with global pincer FAI (15 and 26 patients in low or high resection depth groups, respectively) were included in this study. Both groups showed significant postoperative improvements in the scores of all PROs (p < 0.001). Compared to the low resection depth group, the high resection depth group had a lower degree of improvement through hip arthroscopy, which manifested as lower postoperative mHHS scores (94.29 vs. 85.08, p = 0.006), higher VAS scores (0.93 vs. 2.54, p = 0.002), and lower improvements in VAS (-5.00 vs. -3.35, p = 0.028), HOS-ADL (34.99 vs. 23.90, p = 0.017) and iHOT-12 (39.89 vs. 29.27, p = 0.036). Patients in high resection depth group were less likely to achieve the MCID for the VAS score compared to low resection depth group in significant (73.3 vs. 26.9%, p = 0.004). For patients with global pincer, the outcomes in high resection depth group were slightly worse than the the low resection depth group. It is indicated that excessive resection of the acetabular rim during the procedure should be avoided.

Can modified Dunn radiographs be an alternative to standing AP pelvis radiographs in the evaluation of pincer femoroacetabular impingement?

The purpose of this study was to compare modified Dunn radiographs with standing anteroposterior (AP) pelvis radiographs in respect of the tilt ratio, lateral centre-edge angle (LCEA), crossover sign, crossover percentage and joint space width measurements. The study hypothesis was that modified Dunn radiographs could be an alternative method to standing AP pelvis images in the evaluation of pincer-type femoroacetabular impingement (FAI). The study included 31 patients with a mean age of 42 years (range: 29-55 years) who had modified Dunn and standing AP pelvis radiographs taken in the radiological evaluation of non-traumatic hip pain between July 2018 and September 2022. Similar tilt ratio values were obtained on standing AP and modified Dunn images (P = 0.986). Joint space width showed a decrease in the transition from the modified Dunn position to the standing position, but the difference was not statistically significant (P = 0.161). The mean LCEA was measured as 34° ± 4° in the standing position and as 35° ± 5° in the modified Dunn position. No statistically significant difference was determined in the number of patients with a crossover sign or the crossover percentage values in these patients (P > 0.05). The data obtained in this study showed that there was no significant difference between images taken in the standing and modified Dunn positions in respect of radiological findings of pelvic tilt and pincer-type FAI. The modified Dunn radiograph is equivalent to the standing AP pelvis radiograph for the evaluation of pincer FAI.

Outcomes in Patients with Global Pincer Versus Focal Pincer Femoroacetabular Impingement Treated with Hip Arthroscopy: A Retrospective Study with a Minimum 2-Year Follow-Up.

Global pincer is a relatively rare form of pincer deformity and is typically associated with technical challenges during surgery. So far, controversy remains whether patients with global pincer have equivalent surgical outcomes compared to patients with focal pincer. This study compares the clinical outcomes of arthroscopic treatment between patients with global pincer femoroacetabular impingement (FAI) and focal pincer FAI in the Chinese population. Data were retrospectively collected from patients with global and focal pincer FAI who underwent hip arthroscopy with a minimum two-year follow-up between April 2016 and December 2018. Radiographic measurements, arthroscopic procedures, preoperative and postoperative patient-reported outcomes (PROs) including modified Harris hip score (mHHS), hip outcome score-activities of daily living (HOS-ADL), international hip outcome tool-12 (iHOT-12), and visual analogue scale (VAS) scores, rates of revision surgery and conversion to total hip arthroplasty (THA) were recorded. Achievement of minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) was compared for the VAS, mHHS, HOS-ADL, and iHOT-12 scores between groups. The total of 33 and 167 patients were included in the global and focal group, respectively. There were no intergroup differences in age, gender, body mass index or follow-up times. Lateral center-edge angle (LCEA) was reduced in both groups postoperatively. Both groups demonstrated significant improvements in PROs compared with preoperative levels at the final follow-up. The preoperative scores showed significant differences in terms of mHHS (60.34 vs 62.90, P=0.031) and HOS-ADL (61.45 vs 64.74, P=0.022) scores between two groups, and the improvement of HOS-ADL score was significantly higher in global group (P=0.027). However, the postoperative scores, including VAS, mHHS, HOS-ADL, and iHOT-12 scores, showed no significant differences between two groups. And there were no significant differences in the rate of meeting the PASS and MCID between groups. One (3.0%) in the global group and six (3.6%) patients in the focal group underwent revision arthroscopy respectively, with no significant difference (P=0.876). There were no conversions to THA in both groups. Arthroscopic management of global pincer FAI can achieve excellent functional scores at minimum 2-year follow-up. The outcomes were similar to focal pincer FAI patients with a low rate of secondary procedure.

Определение патогномоничных признакокомплексов при клиническом и МРТ-обследовании внутрисуставных мягкотканных повреждений при посттравматическом коксартрозе

Актуальность. В настоящее время около 60 % внутрисуставных повреждений непосредственно тазобедренного сустава (ТС) диагностируются неправильно из-за отсутствия изменений на рентгенограммах на ранних (дорентгенологических) стадиях. Считается, что диагностика травм и заболеваний, ведущая к нарушению функции ТС, относительно проста. Однако с этим можно согласиться лишь в случаях выраженных морфологических изменений субхондральной кости, когда процесс разрушения суставного хряща достиг значительной степени и изменения в костной ткани компенсируют нагрузку суставных поверхностей. Цель. Определение патогномоничных признакокомплексов (сочетание клинических и МРТ-признаков), характеризующих внутрисуставные мягкотканные повреждения при посттравматическом коксартрозе (ПТ КА). Материалы и методы. Обследованы 30 пациентов с ПТ остеоартрозом ТС I–II стадии. Целью обследования было исследовать информативность и специфичность клинических и лучевых методов исследований по сравнению с артроскопией в диагностике внутрисуставных мягкотканных повреждений у больных на ранних стадиях ПТ КА. Для оценки распространенности внутрисуставных поражений мягко­тканных элементов КС у больных с нарушениями функции ТС (больных с начальными стадиями ПТ КА) и их сочетаний был проведен частотный анализ. Результаты. Определены патогномоничные признакокомплексы (сочетание клинических и МРТ-признаков), характеризующие внутрисуставные повреждения мягкотканных элементов ТС при начальных стадиях ПТ КА. К ним при pincer-ФАК относятся сочетания признаков: FABER (Patrick) + тест Стинчфилда + дегенеративные изменения (разрыв) суставной губы + костные изменения в шейке бедренной кости, импинджмент-тест + FABER (Patrick) + тест Стинчфилда + дегенеративные изменения (разрыв) суставной губы. Определены патогномоничные признакокомплексы (сочетание клинических и МРТ-признаков), характеризующие внутрисуставные поражения мягкотканных элементов ТС при начальных стадиях ПТ КА. К ним при cam-ФАК относятся сочетания признаков: импинджмент-тест + тест Стинчфилда (подъем прям. ноги с преод. сопр.) + дегенеративные изменения (разрыв) суставной губы + угол альфа больше 55°, импинджмент-тест + FABER (Patrick) + тест Стинчфилда + дегенеративные изменения (разрыв) суставной губы, импинджмент-тест + Log roll-тест + дегенеративные изменения (разрыв) суставной губы + угол альфа больше 55°. При определении изолированного ПТ повреждения суставной губы и свободных суставных тел полости ТС при ПТ КА наиболее информативным является сочетание 2 признаков (клинический + МРТ): для изолированного повреждения губы — тест Стинчфилда + МРТ-признак повреждения суставной губы, для наличия свободных суставных тел — тест Стинчфилда + МРТ-признак наличия свободных суставных тел. Признакокомплексы встречались в 100 % случаев. Выводы. Определение вышеупомянутых патогномоничных признакокомплексов будет способствовать улучшению качества диагностики внутрисуставных поражений ТС, их раннему выявлению с последующим оперативным вмешательством, уменьшению прогрессирования остеоартроза ТС.

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.

Arthroscopic Treatment and Outcomes of Borderline Dysplasia With Acetabular Retroversion: A Matched-Control Study From the MASH Study Group

Background: Although acetabular retroversion (AR) occurs in dysplasia, management of the crossover sign (COS) or outcomes in borderline dysplasia (BD) with AR have not been reported. Purpose: To report any differences in the management of the COS in BD and nondysplastic hips and to report comparative outcomes of BD with AR with matched controls with BD or AR (ie, focal pincer femoroacetabular impingement [FAI]). Study design: Cohort study; Level of evidence, 3. Methods: A multicenter matched-pair study was performed with data from a large prospectively collected database. Inclusion criteria were patients who had undergone primary unilateral hip arthroscopy including labral repair for FAI and/or chondral pathology without significant osteoarthritis (ie, Tönnis grade 0 or 1). The study group (BD+AR) was defined radiographically by lateral center-edge angle (LCEA) on standing anteroposterior pelvis of 18° to 25° and positive COS. A 1:1:1 matching on age, sex, and body mass index was performed with a control group with BD and another control group with AR (LCEA, >25°+COS). Acetabuloplasty rates were determined for each group. Mean 2-year outcomes including the 12-Item International Hip Outcome Tool (iHOT-12), minimally clinical important difference (MCID), substantial clinical benefit (SCB), and Patient Acceptable Symptom State (PASS) scores were compared. Subanalysis of the study group both with and without acetabuloplasty was performed. Results: There were 69 patients, with 23 in the study group and 23 in each control group. The effect of dysplasia with or without the presence of the COS resulted in changes in acetabuloplasty rates, with 0% performed in the BD group, 35% in the BD+AR study group, and 91% in the AR group (P = .001). Arthroscopic outcomes demonstrated similar and significant mean 2-year improvement of iHOT-12 patient-reported outcomes, MCID, SCB, and PASS scores in the study and both control groups. There was a trend within the study group toward greater postoperative iHOT-12 scores in patients who received anterior-based acetabuloplasty than those who did not receive acetabuloplasty (81.7 and 70.4, respectively; P = .11). Conclusion: Acetabular coverage influences the management of the COS, with significantly lower acetabuloplasty rates in BD with AR compared with AR without BD (focal pincer impingement). Symptomatic patients with combined BD and AR had similar significant successful outcomes to those of patients with BD and those with AR (focal pincer impingement), whether treated without acetabuloplasty or, less frequently, with limited anterior-based acetabuloplasty.

Acetabular labral reconstruction with medial meniscal allograft: preliminary results of a new surgical technique.

Reconstruction of the acetabular labrum during femoroacetabular impingement (FAI) surgery is accepted when the labrum is deficient and irreparable. Here we describe a novel technique using fresh-frozen medial meniscal allograft for labral reconstruction during surgical hip dislocation for correction of pincer FAI due to acetabular overcoverage. The results from seven hips (six patients) that underwent this procedure with 1 year minimum follow-up, and radiographs are presented. Six of the seven hips had improvements in pain, hip flexion, hip abduction, and Merle d'Aubigné-Postel scores. Only one patient with pre-existing osteoarthritis underwent reoperation with conversion to total hip arthroplasty. All digastric trochanteric osteotomies healed, and there were no cases of femoral head osteonecrosis or progression of Tönnis grades. The medial meniscus is a morphologically and clinically suitable option for labral reconstruction and effectively restores the hip fluid seal.

What Are the Early Outcomes of True Reverse Periacetabular Osteotomy for Symptomatic Hip Overcoverage?

What Are the Early Outcomes of True Reverse Periacetabular Osteotomy for Symptomatic Hip Overcoverage?

Therapeutic Exercise Approaches to Nonoperative and Postoperative Management of Femoroacetabular Impingement Syndrome.

Femoroacetabular impingement syndrome (FAIS) is characterized by premature contact of the femur and acetabulum during hip motion. Morphologic variations of FAIS present as either aspherical femoral deformity (cam femoroacetabular impingement) or overcoverage (pincer femoroacetabular impingement) or both. Patients with FAIS often describe discomfort with hip flexion, adduction, and internal rotation. The use of hip arthroscopy to treat FAIS has risen substantially over the last 15 years. Given that one practice domain of the athletic training profession involves injury prevention and wellness protection, optimal FAIS treatment and management strategies warrant discussion. Sports medicine professionals often help patients with FAIS explore nonoperative exercise strategies and direct rehabilitation exercises for those who pursue surgery. Both approaches demonstrate key pillars of exercise program design, which include postural control, core stabilization, hip strength and motor control, and mobility. The purpose of this article is 2-fold: to present an overview of FAIS, including common diagnostic strategies, and commonalities in therapeutic approaches between nonoperative and postoperative rehabilitation for the treatment and management of patients with FAIS.

Borderline Dysplasia with Acetabular Retroversion: Key Findings from a Large Hip Arthroscopy Study Group

Objectives:The radiographic crossover sign (COS) is an indicator of acetabular retroversion, classically representing anterosuperior overcoverage often treated with acetabuloplasty which could exacerbate acetabular hypovolemia in dysplasia. No prior study has investigated the prevalence of acetabular retroversion in patients with dysplasia undergoing hip arthroscopy, acetabuloplasty rates, and outcomes in this setting.Study objectives are to report the prevalence of acetabular retroversion in dysplasia, the influence of the COS on arthroscopic acetabuloplasty rates, and relative outcomes compared with control groups.Methods:A retrospective cohort study was performed from a prospectively collected multi-center database. Patients undergoing isolated hip arthroscopic surgery were assigned to dysplasia (lateral center-edge angle (LCEA) ≤ 25°) or one of two control groups: normal(LCEA 26-38°), or pincer femoroacetabular impingement (FAI)(LCEA ≥ 39°). The prevalence of COS and acetabuloplasty rates between and within study and control groups were compared (Chi square analysis). Minimum 2 year outcomes utilizing iHOT-12 were compared (analysis of variance).Results:Of 401 study patients, 64 (16%) comprised the dysplasia group, 273 (68%) normal group, and 64 (16%) pincer group. Mean LCEAs were 22.3°, 31.5°, and 42.4°, respectively (p<0.001). COS prevalence was similar between groups at 31%, 26%, and 33%, respectively (p=0.873). Acetabuloplasty rates were dependent on the amount of acetabular coverage with lowered rate in the dysplasia group(40%) and increasing rates in the normal(52%) and the pincer(90%) groups (p=0.013). Post-operative iHOT-12 scores improved in all groups (68, 74, and 77, respectively, p=0.222). Patients with a COS plus rendered acetabuloplasty reported similar scores that improved to 77, 74, and 79, respectively,(p=0.949). Patients with dysplasia with COS averaged 73.1(SD 23.3) iHOT-12 score compared to 67.1(SD: 28.7) for the patients with dysplasia without COS (p=0.466). Within the dysplasia with COS subgroup, there was no significant difference in iHOT-12 scores between the group with acetabuloplasty (77.0;SD:17.1) and without acetabuloplasty (70.4;SD:27.4,p=0.580).Conclusion:Acetabular retroversion occurs with similar prevalence in borderline dysplasia compared with non-dysplastic hips undergoing hip arthroscopy but with lower acetabuloplasty rates not influenced by the COS. Arthroscopic outcomes of dysplasia with retroversion are similarly successful and comparable with those of dysplasia and non-dysplastic hips. Although infrequently performed, acetabuloplasty did not compromise outcomes in dysplasia with retroversion.

Across the Spectrum from Borderline Dysplasia to Global Pincer Femoroacetabular Impingement: Arthroscopic Outcomes from a Large Hip Arthroscopy Study Group

Objectives:Outcomes from hip arthroscopy for dysplasia and global pincer FAI have fallen short of those for patients with normal acetabular coverage, but no study has investigated arthroscopic outcomes across the spectrum of acetabular coverage. Our objective is to report comparative hip arthroscopic outcomes of patients with low (borderline dysplasia), normal, and high (global pincer FAI) lateral acetabular coverage.Methods:A retrospective analysis of prospectively-collected data from a large multi-center registry (seven United States centers) was performed. Primary hip arthroscopy patients were assigned to one of three groups based on preoperative lateral center-edge angle (LCEA): borderline dysplasia (≤25°), normal (26-38°), and pincer FAI (≥39°). Repeated measures ANOVA compared pre-operative to 2-year minimum post-operative iHOT-12 scores. Subsequent ANOVA determined the effect of acetabular coverage on magnitude of change in scores.Results:Of 437 patients, the only statistical difference between groups was lower prevalence of acetabuloplasty in the borderline dysplasia group (p=0.001). A significant improvement in the pre-operative to post-operative iHOT-12 scores for patients with normal acetabular coverage, acetabular undercoverage, and acetabular overcoverage was observed; F(1, 339)=311.06; p<0.001, with no statistical differences in pre-operative (p=0.505) and post-operative (p<0.488) iHOT-12 scores when comparing the groups based on acetabular coverage. Mean iHOT-12 scores increased from 37.3 pre-operatively to 68.7 postoperatively, p<0.001, in the borderline dysplasia group, from 34.4 to 72, p<0.001, in the normal coverage group, and from 35.3 to 69.4, p<0.001, in the pincer group. These pre-operative scores increased by 31.4, 37.8, and 34.1, respectively, with no effect for acetabular coverage on the magnitude of change from pre-operative to post-operative iHOT-12 scores, F(2,339) =1.18; p=0.310. 10 subjects (2.3%) underwent conversion arthroplasty and 19 patients (4.4%) underwent revision arthroscopy with no significant effect of acetabular coverage on the incidence of revision or conversion surgery, X2 (6,433)=11.535, P = 0.073.Conclusion:Lateral acetabular coverage did not influence outcomes from primary hip arthroscopy performed in patients with low (borderline dysplasia), normal, and high (global pincer FAI) LCEA. Borderline dysplasia and moderate global pincer FAI with no or minimal osteoarthritis do not compromise successful 2-year minimum outcomes or survivorship following primary hip arthroscopy when performed by experienced surgeons.

Larger Acetabular Labrum Is Associated With Hip Dysplasia, Joint Incongruence, and Clinical Symptoms

To evaluate the association of labral length with acetabular morphology and clinical symptoms. Patients treated at our hip joint clinic between January 2015 and December 2018 were retrospectively enrolled in the study. Our sample included patients who received a diagnosis of one or more of the following: hip labral tear, femoroacetabular impingement (FAI), and developmental dysplasia of the hip. Patients with osteoarthritis and/or osteonecrosis were excluded. Bilateral labral length was measured as the distance from the acetabular rim to the edge of the labrum at the level of the central coronal T1-weighted magnetic resonance imaging scan cross-referenced to the axial plane (3- to 9-o'clock position). The lateral center-edge angle (LCEA) and acetabular roof obliquity (ARO) were evaluated with plain radiographs. An LCEA of 25° or less was defined as developmental dysplasia of the hip, whereas a positive crossover sign in the presence of an LCEA of 30° or greater, an LCEA greater than 40°, or acetabular inclination lower 0° was defined as pincer FAI. An alpha angle greater than 50° or head-neck offset lower 8 mm was considered cam FAI. The severity of hip symptoms was evaluated bilaterally using the Japanese Orthopaedic Association pain scale, on which hips scoring full points (i.e., a perfect score) were defined as asymptomatic whereas hips with all other scores were considered symptomatic. We used simple linear regression to examine the correlations of labral length with the LCEA and ARO. Labral length was also compared according to patient hip symptom status using the Mann-Whitney U test. The study included 102 patients (14 with bilateral symptoms and 88 with unilateral symptoms). Labral length was strongly correlated with the LCEA (r= -0.612, P < .001) and ARO (r= 0.635, P < .001). Additionally, patients with symptomatic hips had significantly larger labra (9.5 ± 3.0 mm) than those with asymptomatic hips (7.9 ± 2.1 mm, P= .004). Acetabular labral length is significantly greater in dysplastic, irregularly congruent, symptomatic hips. Level Ⅳ, retrospective cross-sectional study.

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.

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.

Arthroscopic Outcomes as a Function of Acetabular Coverage From a Large Hip Arthroscopy Study Group

To report comparative hip arthroscopic outcomes of patients with low (borderline dysplasia), normal, and high (global pincer femoroacetabular impingement [FAI]) lateral acetabular coverage. A retrospective analysis of prospectively collected data from a multicenter registry was performed. Primary hip arthroscopy patients were assigned to 1 of 3 groups based on preoperative lateral center-edge angle: borderline dysplasia (≤25°), normal (25.1°-38.9°), and pincer (≥39°). Repeated-measures analysis of variance compared preoperative with 2-year minimum postoperative International Hip Outcome Tool (iHOT-12) scores. Subsequent analysis of variance determined the effect of acetabular coverage on magnitude of change in scores. Of 437 patients, the only statistical difference between groups was a lower prevalence of acetabuloplasty in the borderline dysplasia group (P= .001). A significant improvement in the preoperative to postoperative iHOT-12 scores for patients with normal acetabular coverage, acetabular undercoverage, and acetabular overcoverage was observed: F(1, 339)= 311.06; P <.001, with no statistical differences in preoperative (P= .505) and postoperative (P <.488) iHOT-12 scores when comparing the groups based on acetabular coverage. Mean iHOT-12 scores increased from 37.3 preoperatively to 68.7 postoperatively (P <.001) in the borderline dysplasia group, from 34.4 to 72 (P <.001) in the normal coverage group, and from 35.3 to 69.4 (P <.001) in the pincer group. These preoperative scores increased by 31.4, 37.8, and 34.1, respectively, with no effect for acetabular coverage on the magnitude of change from preoperative to postoperative iHOT-12 scores: F(2,339)= 1.18; P= .310. Ten patients (2.3%) underwent conversion arthroplasty, and 19 patients (4.4%) underwent revision arthroscopy with no significant effect ofacetabular coverage on the incidence of revision or conversion surgery: χ2 (6,433)= 11.535; P= .073. Lateral acetabular coverage did not influence outcomes from primary hip arthroscopy when performed in patients with low (borderline dysplasia), normal, and high (global pincer FAI) lateral center-edge angle. Borderline dysplasia and moderate global pincer FAI with no or minimal osteoarthritis do not compromise successful 2-year minimum outcomes or survivorship following primary hip arthroscopy when performed by experienced surgeons. Level III, retrospective therapeutic trial.

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.

Automatic MRI-based Three-dimensional Models of Hip Cartilage Provide Improved Morphologic and Biochemical Analysis.

The time-consuming and user-dependent postprocessing of biochemical cartilage MRI has limited the use of delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). An automated analysis of biochemical three-dimensional (3-D) images could deliver a more time-efficient and objective evaluation of cartilage composition, and provide comprehensive information about cartilage thickness, surface area, and volume compared with manual two-dimensional (2-D) analysis. (1) How does the 3-D analysis of cartilage thickness and dGEMRIC index using both a manual and a new automated method compare with the manual 2-D analysis (gold standard)? (2) How does the manual 3-D analysis of regional patterns of dGEMRIC index, cartilage thickness, surface area and volume compare with a new automatic method? (3) What is the interobserver reliability and intraobserver reproducibility of software-assisted manual 3-D and automated 3-D analysis of dGEMRIC indices, thickness, surface, and volume for two readers on two time points? In this IRB-approved, retrospective, diagnostic study, we identified the first 25 symptomatic hips (23 patients) who underwent a contrast-enhanced MRI at 3T including a 3-D dGEMRIC sequence for intraarticular pathology assessment due to structural hip deformities. Of the 23 patients, 10 (43%) were male, 16 (64%) hips had a cam deformity and 16 (64%) hips had either a pincer deformity or acetabular dysplasia. The development of an automated deep-learning-based approach for 3-D segmentation of hip cartilage models was based on two steps: First, one reader (FS) provided a manual 3-D segmentation of hip cartilage, which served as training data for the neural network and was used as input data for the manual 3-D analysis. Next, we developed the deep convolutional neural network to obtain an automated 3-D cartilage segmentation that we used as input data for the automated 3-D analysis. For actual analysis of the manually and automatically generated 3-D cartilage models, a dedicated software was developed. Manual 2-D analysis of dGEMRIC indices and cartilage thickness was performed at each "full-hour" position on radial images and served as the gold standard for comparison with the corresponding measurements of the manual and the automated 3-D analysis. We measured dGEMRIC index, cartilage thickness, surface area, and volume for each of the four joint quadrants and compared the manual and the automated 3-D analyses using mean differences. Agreement between the techniques was assessed using intraclass correlation coefficients (ICC). The overlap between 3-D cartilage volumes was assessed using dice coefficients and means of all distances between surface points of the models were calculated as average surface distance. The interobserver reliability and intraobserver reproducibility of the software-assisted manual 3-D and the automated 3-D analysis of dGEMRIC indices, thickness, surface and volume was assessed for two readers on two different time points using ICCs. Comparable mean overall difference and almost-perfect agreement in dGEMRIC indices was found between the manual 3-D analysis (8 ± 44 ms, p = 0.005; ICC = 0.980), the automated 3-D analysis (7 ± 43 ms, p = 0.015; ICC = 0.982), and the manual 2-D analysis.Agreement for measuring overall cartilage thickness was almost perfect for both 3-D methods (ICC = 0.855 and 0.881) versus the manual 2-D analysis. A mean difference of -0.2 ± 0.5 mm (p < 0.001) was observed for overall cartilage thickness between the automated 3-D analysis and the manual 2-D analysis; no such difference was observed between the manual 3-D and the manual 2-D analysis.Regional patterns were comparable for both 3-D methods. The highest dGEMRIC indices were found posterosuperiorly (manual: 602 ± 158 ms; p = 0.013, automated: 602 ± 158 ms; p = 0.012). The thickest cartilage was found anteroinferiorly (manual: 5.3 ± 0.8 mm, p < 0.001; automated: 4.3 ± 0.6 mm; p < 0.001). The smallest surface area was found anteroinferiorly (manual: 134 ± 60 mm; p < 0.001, automated: 155 ± 60 mm; p < 0.001). The largest volume was found anterosuperiorly (manual: 2343 ± 492 mm; p < 0.001, automated: 2294 ± 467 mm; p < 0.001). Mean average surface distance was 0.26 ± 0.13 mm and mean Dice coefficient was 86% ± 3%. Intraobserver reproducibility and interobserver reliability was near perfect for overall analysis of dGEMRIC indices, thickness, surface area, and volume (ICC range, 0.962-1). The presented deep learning approach for a fully automatic segmentation of hip cartilage enables an accurate, reliable and reproducible analysis of dGEMRIC indices, thickness, surface area, and volume. This time-efficient and objective analysis of biochemical cartilage composition and morphology yields the potential to improve patient selection in femoroacetabular impingement (FAI) surgery and to aid surgeons with planning of acetabuloplasty and periacetabular osteotomies in pincer FAI and hip dysplasia. In addition, this validation paves way to the large-scale use of this method for prospective trials which longitudinally monitor the effect of reconstructive hip surgery and the natural course of osteoarthritis. Level III, diagnostic study.

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.