Editorial Commentary: Small Labral Size on Magnetic Resonance Imaging Is an Indication for Labral Reconstruction in the Setting of Revision Hip Arthroscopy.

Revision hip arthroscopy is an increasingly common procedure as rates of primary hip arthroscopy rise. Etiologies for symptom recurrence may include residual femoroacetabular impingement, cam over-resection, labral pathology, chondral wear, adhesions, and instability. This has spawned sophisticated surgical techniques in hip arthroscopy including labral reconstruction. Indications for labral reconstruction in the revision setting obviously include labral deficiency. In addition, in the absence of other obvious reasons for failure of the primary procedure, a labral reconstruction should be considered for diminutive labra. The ability to predict labral size before surgery based on magnetic resonance imaging can be invaluable.

Microfracture of Acetabular Chondral Lesions Is Not Superior to Other Cartilage Repair Techniques in Patients With Femoroacetabular Impingement Syndrome: A Systematic Review.

PURPOSE: To perform a systematic review to compare clinical outcomes of hip arthroscopy patients undergoing microfracture (MFx) versus other cartilage repair procedures for chondral lesions of the acetabulum. METHODS: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines by searching PubMed, the Cochrane Library, and Embase to identify comparative studies that directly compared outcomes between MFx and other cartilage repair procedures for full-thickness chondral lesions of the acetabulum identified during hip arthroscopy. The search phrase used was: hip AND arthroscopy AND microfracture. Patients were evaluated based on reoperation rates and patient-reported outcomes. RESULTS: Six studies (all Level III evidence) met inclusion criteria, including a total of 202 patients undergoing microfracture (group A) and 327 patients undergoing another cartilage repair procedure (group B). Mean patient age ranged from 35.0 to 45.0 years. Mean follow-up time ranged from 12.0 to 72.0 months. Significantly better patient-reported outcomes (PROs) were found in patients undergoing treatment with bone marrow aspirate concentrate, microfragmented adipose tissue concentrate, autologous matrix-induced chondrogenesis, and a combination of autologous matrix-induced chondrogenesis and bone marrow aspirate concentrate compared with MFx. No studies found significantly better postoperative PROs in group A. The reoperation rate ranged from 0% to 34.6% in group A and 0% to 15.9% in group B. Three of 5 studies reporting on reoperation rate found a significantly greater reoperation rate in group A, with no difference in the other 2 studies. CONCLUSIONS: The literature on MFx of acetabular chondral lesions is limited and heterogeneous. Based on the available data, MFx alone results in a greater or equivalent reoperation rate and inferior or equivalent PROs compared with other cartilage repair procedures for acetabular chondral lesions in patients with femoroacetabular impingement syndrome. LEVEL OF EVIDENCE: Level III, systematic review of level III studies.

[Femoroacetabular impingement in adolescents]. / Femoroazetabuläres Impingement beim Jugendlichen und Adoleszenten.

Femoroacetabular impingement syndrome (FAIS) is caused by a repetitive mechanical conflict between the acetabulum and the proximal femur, occurring in flexion and internal rotation. In cam impingement, bony prominences of the femoral head-neck junction induce chondrolabral damage. The acetabular type of FAIS, termed pincer FAIS, may be either due to focal or global retroversion and/or acetabular overcoverage. Combinations of cam and pincer morphology are common. Pathological femoral torsion may aggravate or decrease the mechanical conflict in FAI but can also occur in isolation. Of note, a high percentage of adolescents with FAI-like shape changes remain asymptomatic. The diagnosis of FAIS is therefore made clinically, whereas imaging reveals the underlying morphology. X­rays in two planes remain the primary imaging modality, the exact evaluation of the osseous deformities of the femur and chondrolabral damage is assessed by magnetic resonance imaging (MRI). Acetabular coverage and version are primarily assessed on radiographs. Evaluation of the entire circumference of the proximal femur warrants MRI which is further used in the assessment of chondrolabral lesions, and also bone marrow and adjacent soft tissue abnormalities. The MRI protocol should routinely include measurements of femoral torsion. Fluid-sensitive sequences should be acquired to rule out degenerative or inflammatory extra-articular changes.

Hip muscle activity in people with hip-related pain compared to asymptomatic controls: A systematic review.

BACKGROUND: Altered hip and thigh muscle activity have been observed across a spectrum of articular hip pathologies, including hip osteoarthritis, femoroacetabular impingement syndrome, and labral pathology. No systematic reviews have examined muscle activity associated with hip pathology and hip-related pain across the life span. A greater understanding of impairments in hip and thigh muscle activity during functional tasks may assist in the development of targeted treatment strategies. METHODS: We conducted a systematic review using the PRISMA guidelines. A literature search was performed in five databases (MEDLINE, CINAHL, EMBASE, Sports Discuss, and PsychINFO). Studies were included that (i) investigated people with hip-related pain (femoroacetabular impingement syndrome, labral tears) or hip osteoarthritis; and (ii) reported on muscle activity using electromyography of hip and thigh muscles during functional tasks such as walking, stepping, squatting, or lunging. Two independent reviewers performed data extraction and assessed risk of bias using a modified version of the Downs and Black checklist. RESULTS: Non-pooled data demonstrated a limited level of evidence. Overall, differences in muscle activity appeared to be more prevalent in people with more advanced hip pathology. CONCLUSIONS: We found that impairments in muscle activity in those with intra-articular hip pathology measured using electromyography were variable but appeared to be greater in severe hip pathology (e.g., hip OA).

Editorial Commentary: In Patients With Hip-Spine Syndrome, a Single Simple Solution May Not Apply: Occam's Razor Becomes Blunt.

The importance of hip-spine syndrome in a nonarthritic population, in which patients present with coexisting symptoms in both the hip and lumbar spine, is becoming more clear. Several studies have shown inferior outcomes in patients undergoing treatment for femoral acetabular impingement syndrome with coexisting spinal symptoms. The most important factor when treating HSS patients is understanding each patient's pathology. A history and physical examination with provocative tests for spinal and hip pathology often provide the answer. Routine standing and seated lateral radiographs are required to assess spinopelvic mobility. If the cause of pain is unclear, diagnostic intra-articular hip injections with local anesthetic and further imaging of the lumbar spine are recommended. In patients with degenerative spine disease with neural impingement, these symptoms may persist after hip arthroscopy, particularly if not improved by intra-articular injections. Patients should be appropriately counseled. If hip symptoms predominate, treatment of femoroacetabular impingement syndrome results in improved outcomes, even with coexisting neural impingement. If spine symptoms predominate, referral to an appropriate specialist may be required. In patients with HSS, Occam's razor becomes blunt; thus, a single simple solution may not apply, and we may need to consider treating each pathology separately.

Does the dGEMRIC Index Recover 3 Years After Surgical FAI Correction and an Initial dGEMRIC Decrease at 1-Year Follow-up? A Controlled Prospective Study.

BACKGROUND: Delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC) allows objective and noninvasive assessment of cartilage quality. An interim analysis 1 year after correction of femoroacetabular impingement (FAI) previously showed that the dGEMRIC index decreased despite good clinical outcome. PURPOSE: To evaluate dGEMRIC indices longitudinally in patients who underwent FAI correction and in a control group undergoing nonoperative treatment for FAI. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: This prospective, comparative longitudinal study included 39 patients (40 hips) who received either operative (n = 20 hips) or nonoperative (n = 20 hips) treatment. Baseline demographic characteristics and presence of osseous deformities did not differ between groups. All patients received indirect magnetic resonance arthrography at 3 time points (baseline, 1 and 3 years of follow-up). The 3-dimensional cartilage models were created using a custom-developed deep learning-based software. The dGEMRIC indices were determined separately for acetabular and femoral cartilage. A mixed-effects model was used for statistical analysis in repeated measures. RESULTS: The operative group showed an initial (preoperative to 1-year follow-up) decrease of dGEMRIC indices: acetabular from 512 ± 174 to 392 ± 123 ms and femoral from 530 ± 173 to 411 ± 117 ms (both P < .001). From 1-year to 3-year follow-up, dGEMRIC indices improved again: acetabular from 392 ± 123 to 456 ± 163 ms and femoral from 411 ± 117 to 477 ± 169 ms (both P < .001). The nonoperative group showed no significant changes in dGEMRIC indices in acetabular and femoral cartilage from baseline to either follow-up point (all P > .05). CONCLUSION: This study showed that 3 years after FAI correction, the dGEMRIC indices improved compared with short-term 1-year follow-up. This may be due to normalized joint biomechanics or regressive postoperative activation of the inflammatory cascade after intra-articular surgery.

Combined femoral and acetabular version and synovitis are associated with dGEMRIC scores in people with femoroacetabular impingement (FAI) syndrome.

This study sought to explore, in people with symptoms, signs and imaging findings of femoroacetabular impingement (FAI syndrome): (1) whether more severe labral damage, synovitis, bone marrow lesions, or subchondral cysts assessed on magnetic resonance imaging (MRI) were associated with poorer cartilage health, and (2) whether abnormal femoral, acetabular, and/or combined femoral and acetabular versions were associated with poorer cartilage health. This cross-sectional study used baseline data from the 50 participants with FAI syndrome in the Australian FASHIoN trial (ACTRN12615001177549) with available dGEMRIC scans. Cartilage health was measured using delayed gadolinium-enhanced MRI of cartilage (dGEMRIC) score sampled at the chondrolabral junction on three midsagittal slices, at one acetabular and one femoral head region of interest on each slice, and MRI features were assessed using the Hip Osteoarthritis MRI Score. Analyses were adjusted for alpha angle and body mass index, which are known to affect dGEMRIC score. Linear regression assessed the relationship with the dGEMRIC score of (i) selected MRI features, and (ii) femoral, acetabular, and combined femoral and acetabular versions. Hips with more severe synovitis had worse dGEMRIC scores (partial η2 = 0.167, p = 0.020), whereas other MRI features were not associated. A lower combined femoral and acetabular version was associated with a better dGEMRIC score (partial η2 = 0.164, p = 0.021), whereas isolated measures of femoral and acetabular version were not associated. In conclusion, worse synovitis was associated with poorer cartilage health, suggesting synovium and cartilage may be linked to the pathogenesis of FAI syndrome. A lower combined femoral and acetabular version appears to be protective of cartilage health at the chondrolabral junction.

Hip Labral Morphological Changes in Patients with Femoroacetabular Impingement Speed Up the Onset of Early Osteoarthritis.

Over the last decade, evidence has mounted for a prominent etiologic role of femoroacetabular impingement (FAI) in the development of early hip osteoarthritis (OA). The aim of this study was to compare the ultrastructure and tissue composition of the hip labrum in healthy and pathological conditions, as FAI and OA, to provide understanding of structural changes which might be helpful in the future to design targeted therapies and improve treatment indications. We analyzed labral tissue samples from five healthy multi-organ donors (MCDs) (median age, 38 years), five FAI patients (median age, 37 years) and five late-stage OA patients undergoing total hip replacement (median age, 56 years). We evaluated morpho-functional by histology and transmission electron microscopy. Extracellular matrix (ECM) structure changes were similar in specimens from FAI compared to those from patients with OA (more severe in the latter) showing disorganization of collagen fibers and increased proteoglycan content. In FAI and in OA nuclei the chromatin was condensed, organelle degenerated and cytoplasm vacuolized. Areas of calcification were mainly observed in FAI and OA labrum, as well as apoptotic-like features. We showed that labral tissue of patients with FAI had similar pathological alterations of tissue obtained from OA patients, suggesting that FAI patients might have high susceptibility to develop OA.

Two Novel Clinical Tests for the Diagnosis of Hip Labral Tears.

BACKGROUND: There are few well-studied clinical tests for the diagnosis of hip labral tears. As the differential diagnosis for hip pain is broad, accurate clinical examination is important in guiding advanced imaging and identifying patients who may benefit from surgical management. PURPOSE: To determine the diagnostic accuracy of 2 novel clinical tests for the diagnosis of hip labral tears. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 2. METHODS: Clinical examination findings including the Arlington, twist, and flexion-adduction-internal rotation (FADIR)/impingement tests as performed by a fellowship-trained orthopaedic surgeon specializing in hip arthroscopy were obtained from retrospective chart review. The Arlington test ranges the hip from flexion-abduction-external rotation to FADIR while applying subtle internal rotation and external rotation motion. The twist test involves internal rotation and external rotation of the hip while weightbearing. Diagnostic accuracy statistics for each of the tests were calculated using magnetic resonance arthrography as the reference standard. RESULTS: A total of 283 patients were included in the study with a mean age of 40.7 years (range, 13-77 years) and 66.4% were women. The Arlington test was found to have a sensitivity of 0.94 (95% CI, 0.90-0.96), specificity of 0.33 (95% CI, 0.16-0.56), positive predictive value (PPV) of 0.95 (95% CI, 0.92-0.97), and negative predictive value (NPV) of 0.26 (95% CI, 0.13-0.46). The twist test was found to have a sensitivity of 0.68 (95% CI, 0.62-0.73), specificity of 0.72 (95% CI, 0.49-0.88), PPV of 0.97 (95% CI, 0.94-0.99), and NPV of 0.13 (95% CI, 0.08-0.21). The FADIR/impingement test was found to have a sensitivity of 0.43 (95% CI, 0.37-0.49), specificity of 0.56 (95% CI, 0.34-0.75), PPV of 0.93 (95% CI, 0.87-0.97), and NPV of 0.06 (95% CI, 0.03-0.11). The Arlington test was significantly more sensitive than both the twist and FADIR/impingement tests (P < .05), while the twist test was significantly more specific than the Arlington test (P < .05). CONCLUSION: The Arlington test is more sensitive than the traditional FADIR/impingement test, while the twist test is more specific than the FADIR/impingement test in diagnosing hip labral tears in the hands of an experienced orthopaedic surgeon.

Editorial Commentary: Treatment of Concomitant Intra-Articular Pathology in Patients With Greater Trochanteric Pain Syndrome Is Indicated by Provocative Impingement or Instability Physical Examination and Ultrasound-Guided Analgesic Injection Testing.

Endoscopic surgery can be used to address peritrochanteric pathology in patients with greater trochanteric pain syndrome. During management of these patients, surgeons must decide whether adjunctive hip arthroscopy to treat concomitant intra-articular pathology (such as labral tears or chondral lesions) is required, because the prevalence of intra-articular findings may be greater than the clinical significance. A thorough history and physical examination can help distinguish whether the symptoms are arising from a peritrochanteric issue (e.g., gluteal tendinopathy, trochanteric bursitis, external coxa saltans) versus an intra-articular pain generator. Increased symptoms with provocative impingement or instability testing indicate adjunctive hip arthroscopy to address intra-articular abnormalities. In addition, an ultrasound-guided analgesic injection into the hip joint or peritrochanteric region may aid in diagnosis. A patient with partial symptomatic relief from separate injections into both areas is a classic presentation and consistent with a mixed-picture of peritrochanteric and intra-articular pathology, which may be addressed with a combined endoscopic and arthroscopic approach.

MRI measurement assessment on ischiofemoral impingement syndrome.

BACKGROUND: To explore the value of MRI upon diagnosis of ischiofemoral impingement syndrome (IFI) and to recognise deformation or oedema of the quadratus femoris muscle. MRI applied to measure the ischial femoral space (IFS), the average width of quadratus femoral space (QFS), and the ischial intertuberal diameter. METHODS: A retrospective analysis was carried out of 213 hip joints MRI images of 58 cases diagnosed with IFI and 61 cases of normal subjects. IFS, QFS and ischial intertuberal diameter were measured by axial T1WI sequence. The morphological and signal changes of the quadratus femoris muscle were observed through proton density weighted image fat suppression sequence (PDWI-FS). RESULTS: The widths of IFS and QFS in the normal group were larger than those in the case group, while the ischial intertuberal diameter was significantly smaller (p < 0.05). Pearson correlation analysis revealed that there was a positive correlation (r = 0.824) between IFS and QFS in all hip joints and a negative correlation between the ischial intertuberal diameter and the widths of IFS and QFS (r = -0.213, -0.222, p < 0.05) respectively. As the grade of oedema in quadratus femoris muscle increased, the corresponding IFS gradually decreased. The corresponding IFS width of grade 0 oedema of the quadratus femoris muscle oedema was significantly higher than that of grade 1, grade 2 and grade 3. The receiver operating characteristic curve (ROC) of the subjects was applied to determine the diagnostic boundary value of the IFS and QFS in IFI patients, which was 1.98 cm and 1.05 cm respectively. The area under the curve (AUC) was 0.948 and 0.953 respectively. CONCLUSIONS: MRI examination could provide a reliable basis for the diagnosis of ischiofemoral impingement syndrome. The narrowing of IFS and QFS with deformation and oedema in the quadratus femoris muscle may be the features of manifestation of IFI.

Amorphous calcium deposits of the hip joint: current observations and state of the scientific discussion.

INTRODUCTION: As a result of increasing hip arthroscopies, rare pathologies as intra-articular amorphous calcium deposits in the capsule-labral (perilabral) recess can be recognized. There is a lack of publications on this pathology. The largest case series included 18 patients. An association between femoroacetabular impingement syndrome (FAIS) and female sex was observed. Furthermore, a correlation between the size of the calcific deposit and the preoperative hip function score was reported. Our hypothesis was that the data of our patient collective with intraoperative amorphous calcium deposits of the hip joint are comparable to the existing data to confirm previous observations. MATERIALS AND METHODS: From 01/2018 to 08/2020, a total of 714 hip arthroscopies were performed. 12 (1.7%) patients who presented intra-articular amorphous calcium deposits during arthroscopy were included. On radiographs, signs of impingement and osteoarthritis were determined. Characteristics and size of the calcific deposits were examined. Preoperative and at the time of follow-up (23 months), patient-reported outcome scores (PROS) were evaluated. Duration of symptoms, pain medication, comorbidities, and return-to-work were evaluated too. RESULTS: The PROS of the four female and eight male patients improved significantly. The average size of the calcific deposit was 6.9 mm in the anteroposterior radiographs. Separation of the calcific deposit from the acetabular rim was seen in nine cases. No correlation between deposit sizes and PROS was found. Cam morphology was treated in ten cases. All patients returned to work after a median of 7 weeks (2.5-13 weeks). CONCLUSION: Amorphous calcium deposits were found in approximately 1% of all hip joints with indication for hip arthroscopy. They are not consistently associated with gender, intra-articular hip pathologies or comorbidities. The clustered occurrence in cam FAI can be justified solely by the fact that impingement is by far the most common indication for hip arthroscopy.

Editorial Commentary: Excessive Femoral Retroversion and Increased Femoral Anteversion Has a Negative Effect on Hip Arthroscopy Outcomes: Symptomatic Extremes of Version Require an Osteotomy.

With the rise in the prevalence of hip arthroscopy, patient selection and proper surgical execution are key to achieving excellent outcomes. As our understanding of femoral acetabular impingement grows, so does our surgical indications to achieve excellent surgical outcomes. Some impingement pathologies are amenable to arthroscopy alone and those with excessive version, dysplasia, Perthese, protrusio, and coxa-vara, or valga require an isolated or combined osteotomy. The version of the femur is known to be a significant source of impingement, and its impact on arthroscopic surgical outcomes has long been assumed to be inconsequential. Those that perform open and arthroscopic hip surgery understand this to be untrue, and arthroscopy alone cannot solve all of our impingement problems.

Endoscopic Ischial Tuberosity Osteophyte Resection for Treatment of Ischiofemoral Impingement: A Case Report.

ABSTRACT: Ischiofemoral impingement is a distinct pathologic finding with abnormal osseous contact between the ischium and the lesser trochanter of the femur. Lesser trochanter excision has been recommended for recalcitrant ischiofemoral impingement through an open or endoscopic approach; however, no study has included ischial tuberosity osteophyte resection and refixation of the hamstring tendon. We report an endoscopic procedure involving ischial tuberosity osteophyte resection with refixation of the partially detached hamstring insertion through a posterior approach in the prone position. Using this technique, it is easier to reach the lesion and less likely to injure the sciatic nerve. The postoperative pain score (visual analogy score) was significantly decreased, the modified Harris hip score increased from 39 preoperatively to 86 postoperatively, and there was no adverse effect on the hamstring tendon.

Normative values of the alpha angle and triangular index measured from the hip radiographs of an African population.

INTRODUCTION: Undetected femoroacetabular impingement (FAI), caused by asphericity of the femoral head, has been implicated as a leading cause of hip osteoarthritis in later stages. Two known types of impingement of the femur head with the acetabulum include the cam-type and pincer type, and the alpha angle and triangular index are indices applied in determining the presence of FAI in a hip radiograph. OBJECTIVE: To determine the normal range and upper limit of normal of the alpha angle and triangular index of an African population using non-pathological hip radiographs. MATERIALS AND METHODS: Hip radiographs of 104 subjects reported to be normal were retrospectively studied. The images were reassessed jointly by three radiographers and afterwards by three consultant radiologists. The alpha angle and triangular index of selected radiographs were measured with appropriate electronic callipers. Values obtained were correlated with the age and gender of the patients. RESULTS: The mean ± SD of the alpha angle for the population studied was 46.70 ± 12.340 with a range of 33.300-96.820 (males: 45.09 ± 12.030, females: 47.32 ± 12.370), and the upper limit of normal obtained was 79.160. The mean triangular index was 1.71±1.38 with a range of 0.03-5.98 (males: 1.77 ± 1.39, females: 1.65 ± 1.36), 4.12 being the upper limit of normal. There was no statistically significant difference between measurements of both indices with age and gender. However, there was excellent agreement between and within raters for both measurements (alpha angle: 0.992; triangular index: 0.924). CONCLUSION: The upper limits of normal for the alpha angle and triangular index of the studied population are 79.160 and 4.12. Age and gender were independent of the values measured, and the measurements demonstrated excellent inter-rater and intra-rater agreement. A normal range is thus provided, with upper limits beyond which a possible femoroacetabular impingement may be diagnosed.

Automated measurement of alpha angle on 3D-magnetic resonance imaging in femoroacetabular impingement hips: a pilot study.

BACKGROUND: Femoroacetabular impingement (FAI) syndrome is an established pre-osteoarthritic condition. Diagnosis is based on both clinical and radiographic parameters. An abnormal manually calculated alpha angle in magnetic resonance imaging (MRI) is traditionally utilized to diagnose abnormal femoral head-neck offset. This pilot study aimed to assess the feasibility of automated alpha angle measurements in patients with FAI syndrome, and to compare automated with manual measurements data with regard to the time and effort needed in each method. METHODS: Alpha angles were measured with manual and automated techniques, using postprocessing software in nineteen hip MRIs of FAI syndrome patients. Two observers conducted manual measurements. Intra- and inter-observer reproducibility and correlation of manual and automated alpha angle measurements were calculated using intra-class correlation (ICC) analysis. Both techniques were compared regarding the time taken (in minutes) and effort required, measured as the amount of mouse button presses performed. RESULTS: The first observer's intra-observer reproducibility was good (ICC 0.77; p < 0.001) while the second observer's was good-to-excellent (ICC 0.93; p < 0.001). Inter-observer reproducibility between both observers in the first (ICC 0.45; p < 0.001) and second (ICC 0.56; p < 0.001) manual alpha angle assessment was moderate. The intra-class correlation coefficients between manual and automated alpha angle measurements were ICC = 0.24 (p = 0.052; observer 1, 1st measurement), ICC = 0.32 (p = 0.015; observer 1, 2nd measurement), ICC = 0.50 (p < 0.001; observer 2, 1st measurement), and ICC = 0.45 (p < 0.001; observer 2, 2nd measurement). Average runtime for automatic processing of the image data for the automated assessment was 16.6 ± 1.9 min. Automatic alpha angle measurements took longer (time difference: 14.6 ± 3.9 min; p < 0.001) but required less effort (difference in button presses: 231 ± 23; p < 0.001). While the automatic processing is running, the user can perform other tasks. CONCLUSIONS: This pilot study demonstrates that objective and reliable automated alpha angle measurement of MRIs in FAI syndrome hips is feasible. Trial registration The Ethics Committee of the University of Düsseldorf approved our study (Registry-ID: 2017084398).

Editorial Commentary: The Measurement of the Alpha Angle in Femoroacetabular Impingement Syndrome With a 45° Dunn-View Radiograph Predicts the Cartilage Damage on the Acetabular Side of the Hip Joint-Is It as Simple as That?

In recent years, femoroacetabular impingement syndrome (FAIS) has developed itself into a well-known pathology throughout the orthopaedic community worldwide. The more we learned, the more sophisticated it became: In the beginning, we measured the femoral head-neck offset; then, the alpha angle was found to be a useful measurement in detecting FAIS. We learned to perform these measurements with, for example, the 45° Dunn view. The alpha angle, but not the femoral head-neck offset, measured as described, predicts not only the acetabular cartilage damage resulting from FAIS but also the correlation between the degree of the alpha angle and the severity of the cartilage damage within the acetabular labrum articular disruption and Outerbridge classifications. The femoral head-neck offset cannot provide us with this information, but it is the first sign we all look at before taking any measurements on radiographs or magnetic resonance imaging scans if a cam morphology could be present. It is paramount to understand the underlying problems of the individual hip and distinguish instability (dysplasia) from FAIS and also to evaluate femoral torsional abnormalities to perform the appropriate treatment using magnetic resonance imaging and computed tomography scans if necessary. The alpha angle quantifies the severity of the pathology and predicts the possible cartilage damage in FAIS patients, but in our opinion, we cannot neglect the femoral head-neck offset, because it is often the first radiologic sign of FAIS that most of us realize on a radiograph. Therefore, both signs have their place in detecting and treating FAIS.

Otto Aufranc Award: Identification of Key Molecular Players in the Progression of Hip Osteoarthritis Through Transcriptomes and Epigenetics.

BACKGROUND: This study aimed: (1) to compare the transcriptome profile of articular cartilage in cam-FAI (early stage) to advanced OA secondary to cam-FAI (late stage) and (2) to investigate epigenetic changes through the expression of DNA methylation enzymes DNMT3B, DNMT1, and DNMT3A and peroxisome proliferator-activated receptor gamma (PPARγ) in human cartilage samples during the progression of hip OA. METHODS: Full-thickness cartilage samples were collected from the anterolateral head-neck junction (impingement zone) of 22 patients (9 early-FAI and 13 late-FAI). RNA sequencing and in vitro cartilage cultures with histological analysis and immunohistochemistry staining for PPARγ and DNMT3B were performed. Target gene validation was confirmed with RT-PCR. RESULTS: Fifty genes and 42 pathways were identified differentially between early and late-FAI (fold change <-1.5 or >1.5, P < .01). PPARγ and DNMT3B were gradually suppressed with disease progression. Contrarily, disease progression induced expression of DNMT1/3A. CONCLUSION: By comparing comprehensive gene expression in early and late stage hip degeneration at the whole-genome level, distinct transcriptome profiles for early and late stage disease were identified along with key molecular contributors to the progression of hip OA. Preservation of endogenous PPARγ may have therapeutic potential to delay or prevent hip OA.

Editorial Commentary: Low-Radiation Dose 3-Dimensional Computed Tomography Scan Reconstruction Is the Best Way to Visualize the Anterior Inferior Iliac Spine-For Now.

Femoroacetabular impingement comes in several anatomic variations that may coexist, and subspine impingement is a commonly discussed cause of indirect extra-articular hip pathology. Although a classification system to identify and understand anterior inferior iliac spine morphology has been in place for some time, attempts have been made to visualize and understand the anatomy based on other imaging modalities. Standard radiographs are a common part of the initial patient evaluation pathway, along with thorough history taking and physical examination findings. Magnetic resonance imaging scans are obtained typically to evaluate the soft tissue, muscle, ligaments, articular cartilage, and labrum for pathology. For many hip preservation surgeons, a computed tomography scan with 3-dimensional reconstruction is standard protocol for patients who progress along the treatment pathway toward a surgical procedure because understanding the complex hip anatomy is key to successful surgical treatment. Many hip arthroscopy patients are in their young adult years, and we always attempt to reduce the amount of radiation exposure. Eliminating this computed tomography scan and using standard-of-care magnetic resonance imaging to simplify patient care, reduce radiation, and reduce health care costs would certainly be beneficial to our hip preservation patients.

Three-Dimensional Morphometric Characterization of Femoral Cam Lesions: Quantifying the Radial and Lateral Extents.

OBJECTIVE: To quantify the radial and lateral extents of femoral cam lesions in FAI patients relative to the alpha angle and correlate with clinical data. METHODS: Retrospective study of 81 hips with femoral cam morphology that underwent arthroscopic surgery between 2017 and 2019. At each hour over the clockface, the alpha angle (α) (abnormal defined as > 55°), radial extent, and lateral extent of cam lesions were measured on CT. These measurements were correlated with clinical and arthroscopic data. Statistics included independent samples t-test and chi-squared test with Bonferroni correction and multivariate logistic regression. RESULTS: Larger α at 12:00-4:00 in males vs females (56.6-63.4° vs 44.3-58.5°, P < 0.001) and at 2:00-4:00 with elite sports participation vs without (56.7-70.9° vs 49.6-61.1°, P ≤ 0.004). Independent risk factors for radial extent beyond 12:00-3:00 were: male sex (OR 4.82, 95% CI [1.46, 15.85], P = 0.010), BMI > 25 (OR 4.74, 95% CI [1.61, 14.00], P = 0.005), and elite sports participation (OR 3.28, 95% CI [1.09, 9.82], P = 0.034). Lateral extent increased at 1:00-4:00 in males vs females (7.8-18.6 mm vs 1.6-9.1 mm, P < 0.0001). A 16% prevalence of distal cam lesions was found at locations with normal α, resulting in underestimation of radial extent by an average of 1.7 hours. CONCLUSION: There is a positive correlation between the alpha angle, lateral extent, and radial extent of cam lesions. FAI patients who were male, participated in elite level sports, and had a BMI > 25 had larger cam lesions. A larger alpha angle is a risk factor for cartilage damage. Patients may have distal cam lesions at locations with normal alpha angles, though their significance is unknown.