Retroversion of the acetabulum. A cause of hip pain

Roles of combined femoral and acetabular anteversion in pathological changes of hip dysplasia and hip reconstructive surgery

Combined femoral and acetabular anteversion is the sum of femoral and acetabular anteversion, representing their morphological relationship in the axial plane. Along with the increasing understanding of hip dysplasia in recent years, numerous scholars have confirmed the role of combined femoral and acetabular anteversion in the pathological changes of hip dysplasia. At present, the reconstructive surgery for hip dysplasia includes total hip replacement and redirectional hip preservation surgery. As an important surgery index, combined femoral and acetabular anteversion have a crucial role in these surgeries. Herein, we discuss the role of combined femoral and acetabular anteversion in pathological changes of hip dysplasia, total hip replacement, and redirectional hip preservation 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.

CT-based morphological study of the pelvis in patients with gluteal muscle contracture

BACKGROUND

In the clinic, gluteal muscle contracture (GMC) causes pelvic structural changes, including acetabular retroversion. However, its causes and forms are not well understood. This study aimed to investigate and analyse the clinical significance of pelvic structural differences between GMC patients and healthy individuals.

METHODS

As the GMC group, we identified 100 GMC patients who received treatment and met the inclusion criteria between January 2019 and January 2020. Control subjects were drawn from the hospital's emergency trauma patients who had no history of pelvic or hip joint disease. All subjects underwent CT scans to measure their pelvic rotation, including the superior iliac angle (SIA), inferior iliac angle (IIA), and ischiopubic angle (IPA), and acetabular coverage, which includes anterior acetabular sector angle (AASA), posterior acetabular sector angle (PASA), horizontal acetabular sector angle (HASA), and superior acetabular sector angle (SASA).

RESULTS

The SIA, IIA, IPA, and PASA of the GMC group were considerably smaller than those of the control group, while the AASA of the GMC group was higher, indicating a statistically significant difference (P < 0.05). The HASA and SASA of the GMC group, on the other hand, were not considerably different from those of the control group. The angles in the GMC group were relativized as follows: The HASA had a positive correlation with the AASA and PASA (r = 0.750, P < 0.01; r = 0.749, P < 0.01); the SASA had a positive correlation with the AASA, PASA, and HASA (r = 0.555, P < 0.01; r = 0.273, P < 0.01; r = 0.552, P < 0.01); the AASA had a negative correlation with the SIA, IIA and IPA (r = - 0.355, P < 0.01; r = - 0.551, P < 0.01; r = - 0.30, P < 0.01); the PASA had a positive correlation with the IIA (r = 0.315, P < 0.01) and had no correlation with the SIA and IPA (P > 0.05); and the IIA had a positive correlation with both the SIA and IPA (r = 0.664, P < 0.01; r = 0.465, P < 0.01).

CONCLUSION

Individuals with GMC have an abnormal pelvic morphology, with acetabular retroversion caused by ilial rotation rather than dysplasia of the acetabular wall.

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

AIMS

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.

METHODS

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).

RESULTS

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.

CONCLUSION

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 Res 2023;12(1):22-32.

Periacetabular osteotomy: A novel application of modified Stoppa approach

Background: The Bernese periacetabular osteotomy (PAO) is a well-established procedure for symptomatic hip dysplasia in adolescents and young adults. However, it remains a technically demanding procedure, and several major complications have been described, many of which are related to the approach and surgical exposure. The current study evaluates the efficacy and safety of PAO performed through a modified Stoppa approach. Methods: A prospective series of nine consecutive patients with hip dysplasia were treated PAO through the modified Stoppa approach. The mean age was 22.4 years (15–30 years) and the mean follow-up was 3.2 years (2–5 years). Harris hip score (HHS) was used as a functional score, and the radiographic indices included the lateral center-edge angle (LCEA) and Tönnis roof angle. Results: The approach allowed the osteotomy lines to be performed under direct visualization from the intra-pelvic surface of the acetabulum, aided by fluoroscopy. A lateral window was added to perform the final iliac cut and for subsequent mobilization and fixation of the acetabular fragment. The mean HHS improved significantly from 70.8 ± 4.9 points to 90.1 ± 3.3 points (p < 0.001). The mean LCEA improved from 8.2° ± 4.9 (range: 0–14) to 32.7° ± 5.3 (range: 26–40), with a mean improvement of 24.5°. The mean Tönnis angle improved from 28.4° ± 4.4 (range: 22–35) to 3.8° ± 3.3 (range: 0–10). Two patients had irritation from prominent screw heads that necessitated removal 1 year after the index procedure. One patient had radiographic progression of osteoarthritis. No cases of infection, non-union, heterotopic ossification, or nerve palsy were identified till the latest follow-up. Conclusion: Ganz PAO can be safely conducted through the modified Stoppa approach, providing direct exposure to the osteotomized surfaces, and protecting susceptible neuro-vascular structures.

Level of evidence: IV.

Evaluation of additional causes of hip pain in patients with femoroacetabular impingement syndrome

Femoroacetabular impingement syndrome (FAIS) is an increasingly prevalent pathology in young and active patients, that has contributing factors from both abnormal hip morphology as well as abnormal hip motion. Disease progression can be detrimental to patient quality of life in the short term, from limitations on sport and activity, as well as the long term through early onset of hip arthritis. However, several concurrent or contributing pathologies may exist that exacerbate hip pain and are not addressed by arthroscopic intervention of cam and pincer morphologies. Lumbopelvic stiffness, for instance, places increased stress on the hip to achieve necessary flexion. Pathology at the pubic symphysis and sacroiliac joint may exist concurrently to FAIS through aberrant muscle forces. Additionally, both femoral and acetabular retro- or anteversion may contribute to impingement not associated with traditional cam/pincer lesions. Finally, microinstability of the hip from either osseous or capsuloligamentous pathology is increasingly being recognized as a source of hip pain. The present review investigates the pathophysiology and evaluation of alternate causes of hip pain in FAIS that must be evaluated to optimize patient outcomes.

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

Aims

The 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.

Methods

A 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.

Results

A 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°).

Conclusion

Patients 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.

Pelvic tilt from supine to standing in patients with symptomatic acetabular retroversion of the hip

AIMS

Acetabular retroversion is a recognized cause of hip impingement and can be influenced by pelvic tilt (PT), which changes in different functional positions. Positional changes in PT have not previously been studied in patients with acetabular retroversion.

METHODS

Supine and standing anteroposterior (AP) pelvic radiographs were retrospectively analyzed in 69 patients treated for symptomatic acetabular retroversion. Measurements were made for acetabular index (AI), lateral centre-edge angle (LCEA), crossover index, ischial spine sign, and posterior wall sign. The change in the angle of PT was measured both by the sacro-femoral-pubic (SFP) angle and the pubic symphysis to sacroiliac (PS-SI) index.

RESULTS

In the supine position, the mean PT (by SFP) was 1.05° (SD 3.77°), which changed on standing to a PT of 8.64° (SD 5.34°). A significant increase in posterior PT from supine to standing of 7.59° (SD 4.5°; SFP angle) and 5.89° (SD 3.33°; PS-SI index) was calculated (p < 0.001). There was a good correlation in PT change between measurements using SFP angle and PS-SI index (0.901 in the preoperative group and 0.815 in the postoperative group). Signs of retroversion were significantly reduced in standing radiographs compared to supine: crossover index (0.16 (SD 0.16) vs 0.38 (SD 0.15); p < 0.001), crossover sign (19/28 hips vs 28/28 hips; p < 0.001), ischial spine sign (10/28 hips vs 26/28 hips; p < 0.001), and posterior wall sign (12/28 hips vs 24/28 hips; p < 0.001).

CONCLUSION

Posterior PT increased from supine to standing in patients with symptomatic acetabular retroversion. The features of acetabular retroversion were less evident on standing radiographs. The low PT angle in the supine position is a factor in the increased appearance of acetabular retroversion. Patients presenting with symptoms of hip impingement should be assessed by supine and standing pelvic radiographs to highlight signs of acetabular retroversion, and to assist with optimizing acetabular correction at the time of surgery. Cite this article: Bone Joint J 2022;104-B(7):786-791.

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

OBJECTIVE

To investigate acetabular cartilage thickness among (1) 8 measurement locations on the lunate surface and (2) different types of femoroacetabular impingement (FAI).

DESIGN

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).

RESULTS

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).

CONCLUSION

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.

Is Stage 2 idiopathic osteonecrosis of the hip joint associated with version angles on imaging methods?

Objectives

In this study, we aimed to investigate whether anatomical variations of acetabulum were associated to idiopathic osteonecrosis (ON) of the femoral head.

Patients and methods

Between January 2014 and March 2020, a total of 46 patients (32 males, 14 females; mean age: 43 years; range, 18 to 66 years) who were diagnosed with unilateral or bilateral ON of the hip joint and 44 healthy age- and sex-matched controls (30 males, 14 females; mean age: 46 years; range, 18 to 79 years) with no signs of ON of the hip joint were retrospectively analyzed. For both groups, measurements were taken of the anatomic parameters, including the acetabular version angle (VA), the sharp angle (SA), and the center-edge angle (CEA) on anteroposterior pelvic radiographs and magnetic resonance imaging (MRI) scans.

Results

The mean VA of both hips was found to be significantly smaller in Group 1 than in Group 2 on both MRI and X-ray (14.9±4.1 and 14.4±3.1 vs. 17.3±3.9 and 18.0±3.7, respectively; p=0.004, p<0.001). The mean SA of both hips was found to be significantly smaller in Group 1 than in Group 2 on both MRI and X-ray (39.0±2.9 and 38.9±2.8 vs. 41.6±3.9 and 40.8±4.9, respectively; p=0.001, p=0.036). The mean CEA of both hips was found to be significantly larger in ON group than in control group on both MRI and X-ray (36.7±6.1 and 36.9±7.0 vs. 32.0±6.0 and 31.5±7.5, respectively; p<0.001, p=0.001).

Conclusion

Version angles were found to be smaller in patients with ON and more acetabular coverage was observed. Greater coverage of the acetabulum may indicate early collapses of the femoral head even in Stage 2 ON patients. The smaller version angles may be associated with ON.

Acetabular Morphology and Spinopelvic Characteristics: What Predominantly Determines Functional Acetabular Version?

Background:

In addition to the relative size of the acetabular rim and how the pelvis is positioned in space, the plane in which the acetabular version is calculated also affects its measurement.

Purpose:

To determine the relative contribution of pelvic and acetabular characteristics on morphological version (measured relative to the anterior pelvic plane angle [APPA]) and functional version (measured relative to the horizontal table).

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

Included were 50 acetabular dysplasia patients and 109 asymptomatic controls. Using image analysis software, morphological parameters of the pelvis and acetabulum were determined from 2-dimensional computed topography: pelvic incidence, pelvic tilt angle, sacral slope, APPA, morphological and functional acetabular versions, and subtended angles (measure of acetabular rim prominence relative to the femoral head center) around the acetabular clockface in 30° increments. Correlation and multivariable regression analyses were performed with morphological and functional version as dependent variables and spinopelvic and acetabular parameters as independent variables.

Results:

Morphological version was moderately associated with differences between anterior and posterior subtended angles (R = 0.68 [P < .001] and R = 0.57 [P < .001] for differences at 165° and 15° and 135° and 45°, respectively). Functional version was moderately associated with pelvic tilt angle (R = 0.56; P <.001) and the difference in subtended angles between anterior and posterior rims (R = 0.61 [P < .001] and R = 0.50 [P < .001] for differences at 165° and 15° and 135° and 45°, respectively). Multivariate analysis revealed a good model for predicting morphological version (R² = 0.44; P < .01) and functional version (R² = 0.58; P < .01). Subtended angle difference between 165° and 15° (B = 0.36 [95% CI, 0.24-0.49]; P < .001) was most strongly related to morphological version, and pelvic tilt angle (B = 0.57 [95% CI, 0.46-0.68]; P < .001) was most strongly related to functional version.

Conclusion:

Functional acetabular version was influenced most strongly by pelvic tilt angle rather than the relative prominence of the acetabular rims. Before determining surgical management for version abnormalities, it would be prudent to assess pelvic mobility and characteristics in different functional positions. In patients with minimal pelvic tilt change dynamically, corrective osteotomy would be the treatment of choice to improve functional version.

Addressing intraarticular pathology at the time of anteverting periacetabular osteotomy for acetabular retroversion is associated with better short-term patient-reported outcomes

Periacetabular osteotomy (PAO) is effective in the management of developmental dysplasia of the hip and femoroacetabular impingement secondary to acetabular retroversion. During anteverting PAO for acetabular retroversion, the need for both labral treatment and femoral head–neck junction osteochondroplasty remains equivocal. Accordingly, this study evaluated patient-reported outcome measures (PROM) and reoperation rates after anteverting PAO with or without intraarticular intervention. Cases of anteverting PAO performed at a single institution between November 2009 and January 2016 were retrospectively reviewed. Patients were divided into three groups: no intervention and intraarticular intervention with arthrotomy or arthroscopy. Subsequently, patients were reclassified by the intraarticular procedure performed at surgery into major (labral repair, femoral head–neck osteochondroplasty) and minor (labral debridement, femoral/acetabular chondroplasty) groups. The cohort was 75% female, median age was 19.5 years and mean body mass index was 25.0 kg/m². Preoperative to postoperative improvement was compared to minimal clinically important differences (MCID) for eight PROM. Patients receiving major interventions exceeded MCID in a greater proportion of PROM compared to minor and no intervention groups (P < 0.007); major or minor interventions did not increase the risk of reoperation over no intervention (P ≥ 0.39). Based on the current data, surgeons performing anteverting PAO for acetabular retroversion should perform arthroscopic or open labral repair and assess for impingement after the correction and perform a head–neck junction osteochondroplasty if indicated.

Lower pelvic tilt, lower pelvic incidence, and increased external rotation of the iliac wing in patients with femoroacetabular impingement due to acetabular retroversion compared to hip dysplasia

AIMS

The effect of pelvic tilt (PT) and sagittal balance in hips with pincer-type femoroacetabular impingement (FAI) with acetabular retroversion (AR) is controversial. It is unclear if patients with AR have a rotational abnormality of the iliac wing. Therefore, we asked: are parameters for sagittal balance, and is rotation of the iliac wing, different in patients with AR compared to a control group?; and is there a correlation between iliac rotation and acetabular version?

METHODS

A retrospective, review board-approved, controlled study was performed including 120 hips in 86 consecutive patients with symptomatic FAI or hip dysplasia. Pelvic CT scans were reviewed to calculate parameters for sagittal balance (pelvic incidence (PI), PT, and sacral slope), anterior pelvic plane angle, pelvic inclination, and external rotation of the iliac wing and were compared to a control group (48 hips). The 120 hips were allocated to the following groups: AR (41 hips), hip dysplasia (47 hips) and cam FAI with normal acetabular morphology (32 hips). Subgroups of total AR (15 hips) and high acetabular anteversion (20 hips) were analyzed. Statistical analysis was performed using analysis of variance with Bonferroni correction.

RESULTS

PI and PT were significantly decreased comparing AR (PI 42° (SD 10°), PT 4° (SD 5°)) with dysplastic hips (PI 55° (SD 12°), PT 10° (SD 6°)) and with the control group (PI 51° (SD 9°) and PT 13° (SD 7°)) (p < 0.001). External rotation of the iliac wing was significantly increased comparing AR (29° (SD 4°)) with dysplastic hips (20°(SD 5°)) and with the control group (25° (SD 5°)) (p < 0.001). Correlation between external rotation of the iliac wing and acetabular version was significant and strong (r = 0.81; p < 0.001). Correlation between PT and acetabular version was significant and moderate (r = 0.58; p < 0.001).

CONCLUSION

These findings could contribute to a better understanding of hip pain in a sitting position and extra-articular subspine FAI of patients with AR. These patients have increased iliac external rotation, a rotational abnormality of the iliac wing. This has implications for surgical therapy with hip arthroscopy and acetabular rim trimming or anteverting periacetabular osteotomy (PAO). Cite this article: Bone Jt Open 2021;2(10):813-824.

Interrater Reliability of the Prone Apprehension Relocation Test

Background:

The Prone Apprehension Relocation Test (PART) augments existing radiographic measures and clinical provocative maneuvers in diagnosing hip instability. One measure of the potential clinical utility of the PART depends on the reproducibility of test results by evaluating providers including physicians, licensed athletic trainers, and physical therapists.

Purpose:

To determine the interrater reliability of the PART among health care providers.

Study Design:

Cohort study (diagnosis); Level of evidence, 3.

Methods:

We retrospectively identified patients in our institution’s hip preservation registry who presented between September 2017 and June 2019 for evaluation of hip pain. Patients included in the study had the PART performed by a single physician as well as 1 of 12 physician extenders (a licensed athletic trainer or a physical therapist). The providers were blinded to the findings of the other examining professional. Interrater reliability was assessed using the Cohen κ (≥0.75 was considered excellent; between 0.75 and 0.40, moderate; and ≤0.40, poor).

Results:

A total of 96 patients (190 hips) were included in this study (61 women and 35 men, average age 32 ± 12.1 years). A total of 23 hips had a positive PART from both examiners. Interrater reliability was excellent between health care professionals for the PART when evaluating the right hip (κ = 0.80), left hip (κ = 0.82), and when combining the results for left and right (κ = 0.81). A subanalysis of patients with a positive PART from both raters demonstrated that 19 of the 23 hips had a lateral center-edge angle >25°.

Conclusion:

Our study demonstrated excellent interrater reliability of the PART, supporting its use in the physical evaluation of painful hips.

Is a periacetabular osteotomy as efficacious in retroversion as it is in dysplasia? : The role of femoral anteversion on outcome

Aims

Periacetabular osteotomy (PAO) is an established treatment for acetabular dysplasia. It has also been proposed as a treatment for patients with acetabular retroversion. By reviewing a large cohort, we aimed to test whether outcome is equivalent for both types of morphology and identify factors that influenced outcome.

Methods

A single-centre, retrospective cohort study was performed on patients with acetabular retroversion treated with PAO (n = 62 hips). Acetabular retroversion was diagnosed clinically and radiologically (presence of a crossover sign, posterior wall sign, lateral centre-edge angle (LCEA) between 20° and 35°). Outcomes were compared with a control group of patients undergoing PAO for dysplasia (LCEA < 20°; n = 86 hips). Femoral version was recorded. Patient-reported outcome measures (PROMs), complications, and reoperation rates were measured.

Results

The mean Non-Arthritic Hip Score (NAHS) preoperatively was 58.6 (SD 16.1) for the dysplastic hips and 52.5 (SD 12.7) for the retroverted hips (p = 0.145). Postoperatively, mean NAHS was 83.0 (SD 16.9) and 76.7 (SD 17.9) for dysplastic and retroverted hips respectively (p = 0.041). Difference between pre- and postoperative NAHS was slightly lower in the retroverted hips (18.3 (SD 22.1)) compared to the dysplastic hips (25.2 (SD 15.2); p = 0.230). At mean 3.5 years’ follow-up (SD 1.9), one hip needed a revision PAO and no hips were converted to total hip arthroplasty (THA) in the retroversion group. In the control group, six hips (7.0%) were revised to THA. No differences in complications (p = 0.106) or in reoperation rate (p = 0.087) were seen. Negative predictors of outcome for patients undergoing surgery for retroversion were female sex, obesity, hypermobility, and severely decreased femoral anteversion.

Conclusion

A PAO is an effective surgical intervention for acetabular retroversion and produces similar improvements when used to treat dysplasia. Femoral version should be routinely assessed in these patients and when extremely low (< 0°), as an additional procedure to address this abnormality may be necessary. Females with signs of hypermobility should also be consulted of the likely guarded improvement.

Cite this article: Bone Jt Open 2021;2(9):757–764.

Retroversion of the hemipelvis rather than hypoplastic posterior wall decreases acetabular anteversion in hips affected by Perthes disease

The acetabular retroversion has a moderate incidence of 31-60% in all patients of the Perthes disease. It might be caused by posterior wall dysplasia based on recent animal researches. However, some studies support that hemipelvic retroversion is the main factor for the acetabular retroversion. The primary pathological factor of increasing retroversion angle is still controversial anatomically. This study aimed to identify whether there is acetabular retroversion in children with Perthes disease,and to find a method to distinguish version types. Forty children with unilateral Perthes disease who were admitted to our hospital from January 1, 2012 to December 31, 2018 were enrolled, and 40 controls were matched based on sex and age. The acetabular anteversion angle (AAA), internal wall anteversion angle (IWAA), anterior wall height of the acetabulum (A), acetabular posterior wall height (P), and acetabular width (W) were assessed on computed tomography (CT) at the level of the femoral head center. The acetabular wall difference index (AWDI; AWDI = P-A)/W*100) was calculated. The mean AAA was significantly lower in Perthes disease hips (10.59 (8.05-12.46)) than in contralateral hips (12.04 (9.02-13.33)) (p = 0.002) but did not differ from control hips (9.68 ± 3.76) (p = 0.465). The mean IWAA was significantly lower in Perthes hips (9.16 ± 3.89) than in contralateral hips (11.31 ± 4.04) (p = 0.000) but did not differ from control hips (9.43 ± 3.82) (p = 0.753). The mean AWDI did not differ between Perthes hips (0.41 ± 4.94) and contralateral hips (- 1.12 (- 4.50, 2.17)) (p = 0.06) or control hips (- 0.49 ± 5.46) (p = 0.437). The mean W was significantly higher in Perthes hips (44.61 ± 5.06) than in contralateral hips (43.36 ± 4.38) (p = 0.000) but did not differ from control hips (45.02 ± 5.01) (p = 0.719). The mean A and P did not differ between Perthes hips and contralateral hips or control hips. Correlation analysis of all hip joints revealed a significant correlation between AAAs and IWAAs (r = 0.772; r = 0.643; r = 0.608; and r = 0.540). Linear regression analysis revealed that AAAs increased with IWAAs. Multiple linear regression showed that IWAAs and AWDIs have good predictive value for AAAs in both Perthes and control hips (R² = 0.842, R² = 0.869). In patients with unilateral Perthes disease, the affected acetabulum is more retroverted than that on the contralateral side, which may be caused by hemipelvic retroversion. The measurements in this study could distinguish the form of acetabular retroversion. IWAAs and AWDIs can be used as new observations in future studies of acetabular version.

FAI morphology increases the risk for osteoarthritis in young people with a minimum follow-up of 25 years

INTRODUCTION

The mechanical conflict in symptomatic femoroacetabular impingement can lead to early osteoarthritis. However, radiographic impingement morphology is often seen in asymptomatic individuals. Long-term observation regarding the risk of developing osteoarthritis in these individuals is lacking. Our study addressed the following questions: Does femoroacetabular impingement morphology increase the risk for development of osteoarthritis after at least 25 years? If yes, which radiographic parameter is the most predictive? Does the level of activity influence the risk for development of osteoarthritis? Are PROM influenced by the grade of osteoarthritis in this population?

METHODS

We investigated 51 (32 male, 19 female) patients for whom AP pelvis and Dunn view radiographs were available with a minimum follow-up of 25 years. Alpha angle in AP pelvis and Dunn view radiographs, femoral torsion in Dunn view, lateral center edge angle, cross-over sign, posterior wall sign and prominence of ischial spine sign in AP pelvis radiographs were determined. On the follow-up radiographs, osteoarthritis was graded. Tegner Score for the time of the index radiograph was evaluated. Harris Hip Score and Western Ontario and McMaster Universities Osteoarthritis Index were assessed at latest follow-up.

RESULTS

The mean follow-up was 43 years (range 25-58). Cam impingement morphology showed to increase the risk for development of osteoarthritis: Alpha angles of ≥ 55° on AP pelvis and Dunn view radiographs were associated risk factors and showed an OR of 1.05 (p = 0.002) and 1.10 (p = 0.001), respectively. Abnormal femoral torsion and acetabular retroversion were not risk factors for osteoarthritis. Tegner Score at index presentation, HHS and WOMAC Score did not correlate with the grade of osteoarthritis.

CONCLUSION

This study showed that cam impingement morphology in young patients raises the risk for development of hip osteoarthritis by 5-10% in a long-term follow-up with a minimum of 25 years, thus its contribution was small.

A three-dimensional measurement method on MR arthrography of the hip to classify femoro-acetabular impingement

PURPOSE

(1) To investigate correlations between different types of FAI and the ratio of acetabular volume (AV) to femoral head volume (FV) on MR arthrography. (2) To assess 2D/3D measurements in identifying different types of FAI by means of cut-off values of AV/FV ratio (AFR).

MATERIALS AND METHODS

Alpha angle, cranial acetabular version, acetabular depth, lateral center edge angle, AV, and FV of 52 hip MR arthrography were measured. ANOVA test correlated different types of FAI with AFR. ROC curves classified FAI by cut-off values of AFR. Accuracy of 2D/3D measurements was calculated.

RESULTS

ANOVA test showed a significant difference of AFR (p value < 0.001) among the three types of FAI. The mean values of AFR were 0.64, 0.74, and 0.89 in cam, mixed, and pincer types, respectively. Cut-off values of AFR were 0.70 to distinguish cam types from mixed and pincer types, and 0.79 to distinguish pincer types from cam and mixed types. Cut-off values identified 100%, 73.9%, and 55.6% of pincer, cam, and mixed types. 2D and 3D classifications of FAI showed accuracy of 40.4% and 73.0%.

CONCLUSIONS

3D measurements were clearly more accurate than 2D measurements. Distinct cut-off values of AFR discriminated cam types from pincer types and identified pincer types in all cases. Cam and mixed types were not accurately recognized.

MRI-based assessment of acetabular version and coverage after previous Pemberton osteotomy in skeletally mature patients

PURPOSE

In hip dysplasia the Pemberton osteotomy can modify the shape of the acetabulum and is indicated for children aged between two and 12 when the triradiate cartilage is still open. However, there have been concerns about acetabular retroversion following this type of osteotomy. The studies, however, have been based on plain radiographs. The aim of our investigation was to assess the 3D acetabular orientation in patients with previous Pemberton osteotomy after skeletal maturation.

METHODS

Ten patients with 12 operated hips were included who received Pemberton osteotomy for hip dysplasia between January 3, 2005 and March 25, 2011. Mean age at surgery and at follow-up were 7.2 years (sd 3.7) and 19.2 years (sd 3.7), respectively. MRIs were conducted with 1.5 T. Besides the measurement of acetabular version, the analysis included alpha angles, acetabular sector angles (ASAs) as well as modified ASAs (cartilage covered area angles). Furthermore, the presence of osteoarthritis (OA) as well as acetabular retroversion was determined on plain radiographs. Patient-related outcome measures included the international Hip Outcome Tool (iHOT) and EuroQol-5-Dimensions (EQ5D) scores.

RESULTS

In comparison with the contralateral native and healthy hips the operated hips showed similar version (19.5° (sd 4.6°) versus 18.6° (sd 7.0°); p = 0.974). Also, there were no differences in terms of femoral head sphericity (alpha angles) and acetabular coverage (ASA angles). Five of 12 Pemberton hips showed signs of beginning OA (Kellgren-Lawrence classification I or II) while none of the non-operated hips did. Patients who received surgery before the age of six years had similar functional and radiological results when compared with patients who were older than six years at surgery. Among all patients, iHOT was 91.9 (sd 10.0) and EQ5D was 90.3 (sd 7.3)).

CONCLUSION

The Pemberton osteotomy provides good long-term radiographic and functional results without compromising acetabular version or coverage.

LEVEL OF EVIDENCE

Level III: retrospective comparative study.

Hip arthroscopy with initial access to the peripheral compartment provides significant improvement in FAI patients

PURPOSE

This study was designed to evaluate the clinical and radiographic results of arthroscopic treatment of femoroacetabular impingement (FAI) using the technique of initial access to the peripheral compartment. It is based on a single surgeon large case series with a minimum of 2 years follow-up.

METHODS

Prospective longitudinal study with consecutive patients. Inclusion criteria were the presence of FAI syndrome that had failed non-operative treatment and had a hip arthroscopy with initial access to the peripheral compartment. Exclusion criteria were previous hip surgery, patients younger than 16 or older than 60 years, Tönnis grade ≥ 2 osteoarthritis, hip dysplasia based on radiographic evidence of LCEA less than 25° and workers compensation cases. One hundred and sixty hips met the inclusion criteria, 84 were female and 70 were male patients (six bilateral cases), with a median age of 36 years (range 16-59).

RESULTS

The median alpha angle correction was 22.6º (range 5.9-46.7) (p < 0.01) and the average LCEA correction when acetabuloplasty was undertaken was 6.5º (range - 1.4-20.8) (p < 0.01). The mean NAHS at baseline was 56.1 (range 16-96) and improved to 83.2 at the last follow up (range 44-100) for the patients that had no additional procedure (p < 0.01). The mean average improvement was 27.7º points (range - 16-73). No iatrogenic labral perforation and no full-thickness chondral damage were recorded during the arthroscopic procedures.

CONCLUSIONS

Favourable outcomes are reported for the arthroscopic treatment of FAI with initial access to the peripheral compartment. The technique is protective against iatrogenic chondral and labral damage, more conservative to the joint capsule, but the mean traction time was relatively long when suture anchors were used. The results are comparable to the classic initial central compartment approach.

LEVEL OF EVIDENCE

Level IV.

Prevalence and associated factors of pistol grip deformity in Japanese local residents

Pistol grip deformity (PGD) may be the main factor in femoroacetabular impingement development. This study aimed to clarify the epidemiological indices and factors related to PGD in Japanese people. This population-based cohort study included 1575 local Japanese residents. PGD, center edge angle, and joint space width were measured radiographically. We investigated the relationship between PGD and spino-pelvic parameters. Factors associated with PGD were examined using multiple logistic regression analysis, with the presence/absence of PGD as an objective variable, and sex, age, body mass index (BMI), and the presence/absence of hip pain or spino-pelvic parameters as explanatory variables. In the entire cohort, 4.9% (10.6% men, 2.1% women) had PGD on at least one side. A trend was observed between PGD and increasing age in both men and women (men: p < 0.0001, women: p = 0.0004). No relationship was observed between PGD and hip pain (risk ratio 1.0 [95% confidence interval 0.97–1.03]). Factors significantly associated with PGD were age, sex, and BMI in the multivariate model. Acquired factors may be related to PGD in Japanese people as the PGD prevalence increased with age and PGD was not significantly associated with hip pain. This study provides new insights into the etiology and clinical significance of PGD.

The association of parturition scars and pelvic shape: A geometric morphometric study

OBJECTIVES

Pelvic features, mostly known as parturition scars, have been extensively studied in the last decades and are frequently investigated in archaeological and forensic contexts. It is still unclear, however, whether they really relate to pregnancy and birth, or whether these features are caused by other biomechanical factors. Because the length and difficulty of labor correlates with the form of the birth canal, we studied the association between the expression of pelvic features and pelvic shape using geometric morphometrics.

MATERIALS AND METHODS

We scored the expression of the preauricular sulcus, margo auricularis groove, sacral preauricular extension, dorsal and ventral pubic pitting for 54 individuals from a 19th century collection and 19 individuals from the Bronze Age cemetery of Hainburg-Teichtal, Austria. Based on photogrammetric surface models, pelvic shape was captured by 331 landmarks and semilandmarks. The multivariate association between pelvic features and pelvic shape was explored by partial least squares analysis.

RESULTS

Within the female subsample, we detected a significant association of a constrained birth canal with a strong expression of the preauricular sulcus, the margo auricularis groove, and a retroverted position of the acetabulum. No significant association was found among males.

DISCUSSION

This suggests that difficult or prolonged labor may indeed cause more strongly expressed pelvic features, presumably because of increased strain of the pelvic ligaments during birth. Furthermore, the retroversion of the acetabulum, which is known to cause sacroiliac joint dysfunction, changes the strain on pelvic ligaments and can thus also result in the development of pronounced pelvic features.

Acetabular- and femoral orientation after periacetabular osteotomy as a predictor for outcome and osteoarthritis

BACKGROUND

Periacetabular osteotomy is a successful treatment for hip dysplasia. The results are influenced, however, by optimal positioning of the acetabular fragment, femoral head morphology and maybe even femoral version as well as combined anteversion have an impact. In order to obtain better insight on fragment placement, postoperative acetabular orientation and femoral morphology were evaluated in a midterm follow-up in regard to functional outcome and osteoarthritis progression.

METHODS

A follow-up examination with 49 prospectively documented patients (66 hips) after periacetabular osteotomy (PAO) was performed after 62.2 ± 18.6 months. Mean age of patients undergoing surgery was 26.7 ± 9.6 years, 40 (82%) of these patients were female. All patients were evaluated with an a.p. pelvic x-ray and an isotropic MRI in order to assess acetabular version, femoral head cover, alpha angle, femoral torsion and combined anteversion. The acetabular version was measured at the femoral head center as well as 0.5 cm below and 0.5 and 1 cm above the femoral head center and in addition seven modified acetabular sector angles were determined. Femoral torsion was assessed in an oblique view of the femoral neck. The combined acetabular and femoral version was calculated as well. To evaluate the clinical outcome the pre- and postoperative WOMAC score as well as postoperative Oxford Hip Score and Global Treatment Outcome were analyzed.

RESULTS

After PAO acetabular version at the femoral head center (31.4 ± 9.6°) was increased, the anterior cover at the 15 o'clock position (34.7 ± 15.4°) was reduced and both correlated significantly with progression of osteoarthritis, although not with the functional outcome. Combined acetabular and femoral torsion had no influence on the progression of osteoarthritis or outcome scores.

CONCLUSION

Long-term results after PAO are dependent on good positioning of the acetabular fragment in all 3 planes. Next to a good lateral coverage a balanced horizontal alignment without iatrogenic pincer impingement due to acetabular retroversion, or insufficient coverage of the anterior femoral head is important.

What is the pelvic tilt in acetabular dysplasia and does it change following peri-acetabular osteotomy?

To quantify the pelvic tilt (PT) in patients with symptomatic acetabular dysplasia and determine if it represents a compensatory mechanism to improve femoral head coverage, we studied a cohort of 16 patients undergoing 32 bilateral staged PAOs for acetabular dysplasia and compared this to a matched cohort of 32 patients undergoing PAO for unilateral acetabular dysplasia all with >1 year follow-up. The change in PT was determined with two validated methods, namely, the sacro-femoral-pubic (SFP) angle and the pubic symphysis to sacroiliac index (PS-SI). Despite an improvement in the lateral centre-edge and Tönnis angles to within normal limits following PAO, patients with unilateral and bilateral acetabular dysplasia have similar PT pre-operatively (8° ± 5°) and post-operatively (9° ± 5°). A change of >5° was observed in only six patients (13%) using the SFP angle, and five patients (10%) using the PS-SI, all increased (posterior rotation of the pelvis). No patients were observed to have a change in PT >10°. The observed PT in our study group is equivalent to that found in the normal population and in patient with symptomatic acetabular retroversion. These findings all suggest that PT is morphological rather than a result of a compensatory mechanism, and even if it was compensatory, it does not appear to reverse significantly following PAO. The target for acetabular reorientation, therefore, remains constant.

Hip preservation

Classical indications for hip preserving surgery are: femoro-acetabular impingement (FAI) (intra- and extra-articular), hip dysplasia, slipped capital femoral epiphysis, residual deformities after Perthes disease, avascular necrosis of the femoral head.

Pre-operative evaluation of the pathomorphology is crucial for surgical planning including radiographs as the basic modality and magnetic resonance imaging (MRI) and/or computed tomography (CT) to evaluate further intra-articular lesions and osseous deformities.

Two main mechanisms of intra-articular impingement have been described:

(1) Inclusion type FAI (‘cam type’).

(2) Impaction type FAI (‘pincer type’).

Either arthroscopic or open treatment can be performed depending on the severity of deformity.

Slipped capital femoral epiphysis often results in a cam-like deformity of the hip. In acute cases a subcapital re-alignment (modified Dunn procedure) of the femoral epiphysis is an effective therapy.

Perthes disease can lead to complex femoro-acetabular deformity which predisposes to impingement with/without joint incongruency and requires a comprehensive diagnostic workup for surgical planning.

Developmental dysplasia of the hip results in a static overload of the acetabular rim and early osteoarthritis. Surgical correction by means of periacetabular osteotomy offers good long-term results.

Cite this article: EFORT Open Rev 2020;5:630-640. DOI: 10.1302/2058-5241.5.190074

Hip Stability May Influence the Development of Greater Trochanteric Pain Syndrome: A Case-Control Study of Consecutive Patients

Background:

Greater trochanteric pain syndrome (GTPS) is thought to relate primarily to tendinosis/tendinopathy of the hip abductors. Previous studies have suggested that certain anatomic factors may predispose one to development of the condition.

Hypothesis:

It was hypothesized that intrinsic acetabular bony stability of the hip is related to the development of GTPS.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 198 consecutive patients diagnosed with GTPS were compared with 198 consecutive patients without clinical evidence of GTPS. Electronic health records of the included patients were examined; data recorded included patient age, sex, race, and body mass index (BMI). Standing anteroposterior radiographs were evaluated by 2 blinded examiners who measured the Tönnis angle, lateral center-edge angle (LCEA), and acetabular depth/width ratio (ADW) and assessed for the presence of a posterior wall sign. The number of dysplastic measures was recorded for each patient based on published norms. Associations between radiographic and patient variables versus the presence or absence of GTPS were determined. Factors with univariate associations where P < .20 were included in a binary logistic regression model to identify independent predictors of the presence of GTPS.

Results:

There was no difference between groups in terms of age, BMI, or race. There were significantly more women than men in the GTPS group (71% vs 30%; P < .001). Intraclass correlation coefficients were good for the LCEA (0.82) and Tönnis angle (0.82) and poor (0.08) for the ADW. Kappa was moderate for the presence of a posterior wall sign (0.51). An increased Tönnis angle, decreased ADW, and ADW <0.25 were significantly associated with the presence of GTPS. The binary logistic regression model identified an increased Tönnis angle (P < .010) and female sex (P < .001) as independent risk factors for GTPS.

Conclusion:

Based on this preliminary retrospective study, decreased intrinsic acetabular bony stability of the hip may be associated with an increased risk of GTPS.

Femoroacetabular Impingement and Acetabular Labral Tears - Part 2: Clinical Diagnosis, Physical Examination and Imaging

The clinical diagnosis of femoral acetabular impingement (FAI) continues to evolve as the understanding of normal and pathological hips progresses. Femoral acetabular impingement is currently defined as a syndrome in which the diagnosis consists of the combination of a previously-obtained comprehensive clinical history, followed by a consistent and standardized physical examination with specific orthopedic maneuvers. Additionally, radiographic and tomographic examinations are used for the morphological evaluation of the hip, and to ascertain the existence of sequelae of childhood hip diseases and the presence of osteoarthritis. The understanding of the femoral and acetabular morphologies and versions associated with images of labral and osteochondral lesions obtained through magnetic resonance imaging (MRI) contributes to the confirmation of this syndrome in symptomatic patients, and helps in the exclusion of differential diagnoses such as iliopsoas tendon snaps, subspine impingement, ischiofemoral impingement, and other hip joint pathologies.

Femoroacetabular Impingement and Acetabular Labral Tears - Part 1: Pathophysiology and Biomechanics

Femoroacetabular impingement (FAI) is an important cause of hip pain, and the main etiology of hip osteoarthritis in the young population. Femoroacetabular impingement is characterized by subtle alterations in the anatomy of the acetabulum and proximal femur, which can lead to labrum tearing. The acetabular labrum is essential to the stability of the hip joint. Three types of FAI were described: cam (anespherical femoral head), pincer (acetabular overcoverage) and mixed (characteristics of both cam and pincer). The etiology of FAI is related to genetic and environmental characteristics. Knowledge of this condition is essential to adequately treat patients presenting with hip pain.

The history of femoroacetabular impingement

Aims

Femoroacetabular impingement (FAI) describes abnormal bony contact of the proximal femur against the acetabulum. The term was first coined in 1999; however what is often overlooked is that descriptions of the morphology have existed in the literature for centuries. The aim of this paper is to delineate its origins and provide further clarity on FAI to shape future research.

Methods

A non-systematic search on PubMed was performed using keywords such as “impingement” or “tilt deformity” to find early anatomical descriptions of FAI. Relevant references from these primary studies were then followed up.

Results

Although FAI has existed for almost 5,000 years, the anatomical study by Henle in 1855 was the first to describe it in the literature. The relevance of the deformity was not appreciated at the time but this triggered the development of further anatomical studies. Parallel to this, Poland performed the first surgical correction of FAI in 1898 and subsequently, descriptions of similar procedures followed. In 1965, Murray outlined radiological evidence of idiopathic cam-type deformities and highlighted its significance. This led to a renewed focus on FAI and eventually, Ganz et al released their seminal paper that has become the foundation of our current understanding of FAI. Since then, there has been an exponential rise in published literature but finding a consensus, especially in the diagnosis of FAI, has proven to be difficult.

Conclusion

Current research on FAI heavily focuses on new data, but old evidence does exist and studying it could be equally as important in clarifying the aetiology and classification of FAI.

Cite this article: Bone Joint Res 2020;9(9):572–577.

The Ischial Spine in Developmental Hip Dysplasia: Unraveling the Role of Acetabular Retroversion in Periacetabular Osteotomy

PURPOSE

Radiological diagnosis of acetabular retroversion (AR) is based on the presence of the crossover sign (COS), the posterior wall sign (PWS), and the prominence of the ischial spine sign (PRISS). The primary purpose of the study is to analyze the clinical significance of the PRISS in a sample of dysplastic hips requiring periacetabular osteotomy (PAO) and evaluate retroversion in symptomatic hip dysplasia.

METHODS

In a previous paper, we reported the classic coxometric measurements of 178 patients with symptomatic hip dysplasia undergoing PAO where retroversion was noted in 42% of the cases and was not found to be a major factor in the appearance of symptoms. In the current study, we have added the retroversion signs PRISS and PWS to our analysis. Among the retroverted dysplastic hips, we studied the association of the PRISS with the hips requiring PAO. We also defined the ischial spine index (ISI) and studied its relationship to the coxometric measurements and AR.

RESULTS

In hips with AR, the operated hips were significantly associated with the PRISS compared to the nonoperated ones (χ ² = 4.847). Additionally, the ISI was able to classify acetabular version (anteverted, neutral, and retroverted acetabula). A direct correlation between the ISI and the retroversion index (RI) was found, and the highest degree of retroversion was found when the 3 signs of acetabular retroversion were concomitantly present (RI = 33.6%).

CONCLUSION

The PRISS, a radiographic sign reflecting AR, was found to be significantly associated with dysplastic hips requiring PAO where AR was previously not considered a factor in the manifestation of symptoms and subsequent requirement for surgery. Moreover, the PRISS can also serve as an adequate radiographic sign for estimating acetabular version on pelvic radiographs.

Preoperative anterior coverage of the medial acetabulum can predict postoperative anterior coverage and range of motion after periacetabular osteotomy: a cohort study

BACKGROUND

We hypothesized that preoperative pelvic morphology may affect postoperative anterior coverage and postoperative clinical range of motion (ROM) leading to postoperative pincer type femoroacetabular impingement (FAI). The aim of this study was to evaluate the relationships between preoperative bone morphology and postoperative ROMs to prevent postoperative FAI after periacetabular osteotomy.

METHODS

Sixty-eight patients (71 hips) with hip dysplasia participated in this study and underwent curved PAO. The acetabular fragment was usually moved only by lateral rotation of the acetabulum, without intraoperative anterior or posterior rotation. The pre- and postoperative three-dimensional center-edge (CE) angles were measured and compared to the postoperative ROM.

RESULTS

Preoperative medial anterior CE angle was significantly associated with postoperative anterior CE angle, and the correlation coefficient of medial anterior CE and postoperative anterior CE was higher than the coefficient of preoperative anterior CE and postoperative anterior CE (preoperative anterior CE, rr = 0.27, p = 0.020; preoperative medial anterior CE, rr = 0.54, p < 0.001). Femoral anteversion correlated with postoperative internal rotation angle at 90° flexion (r = 0.32, p = 0.021). In multiple linear regressions, postoperative internal rotation angle at 90° flexion angle was significantly affected by both medial CE angle through the medial one fourth of femoral head and femoral anteversion.

CONCLUSIONS

Preoperative medial anterior acetabular coverage was associated with postoperative anterior acetabular coverage. Further, the combination with preoperative medial anterior acetabular coverage and femoral anteversion can predict postoperative internal rotation at 90° flexion. Therefore, the direction of acetabular reorientation should be carefully considered when the patients have high preoperative medial anterior CE angle and small femoral anteversion.

Is Hip Arthroscopy an Adequate Therapy for the Borderline Dysplastic Hip? Correlation Between Radiologic Findings and Clinical Outcomes

Background

Recent studies have shown that assessment of the lateral center-edge angle (LCEA) between 18° and 25° is not sufficient to adequately classify mildly dysplastic hips and that further radiological features should be considered. However, no correlation between different morphologic features and clinical outcomes has been investigated so far.

Purpose

To analyze the clinical outcomes of patients with different subtypes of borderline dysplastic hips who underwent arthroscopic surgery.

Study Design

Cohort study; Level of evidence, 3.

Methods

We examined patients with an LCEA between 18° and 25° who underwent arthroscopic treatment for femoroacetabular impingement syndrome between January 2015 and December 2016. A hierarchical cluster analysis was performed to identify hip morphologic subtypes according to radiographic parameters, including the LCEA, femoro-epiphyseal acetabular roof (FEAR) index, anterior and posterior wall indices (AWI and PWI), Tönnis angle, alpha angle, and femoral neck-shaft angle. In addition, the International Hip Outcome Tool 12 (iHOT-12) and a visual analog scale (VAS) for pain were applied preoperatively and at follow-up, and the results were compared among the different clusters. Previously reported minimal clinically important difference (MCID) and patient acceptable symptomatic state (PASS) values were used to determine clinically significant improvements.

Results

A total of 40 patients were identified. Of these, 36 patients were available for evaluation at a mean follow-up of 43.8 months. In total, 4 sex-independent clusters with different morphologic patterns of the hip were identified: cluster 1, unstable anterolateral deficiency (FEAR index >2°, AWI <0.35); cluster 2, stable anterolateral deficiency (FEAR index <2°, AWI <0.35); cluster 3, stable lateral deficiency (FEAR index >2°, normal AWI and PWI); and cluster 4, stable posterolateral deficiency (FEAR index <2°, PWI <0.85). At follow-up, clusters 1, 2, and 3 showed significantly improved iHOT-12 (P < .0001) and VAS pain (P < .0001) scores, and cluster 4 showed no significant improvements. The MCID of 15.2 points was achieved by all patients in clusters 2 and 3, by 63% of patients in cluster 1, and by 23% of patients in cluster 4. Clusters 2 and 3 differed significantly from clusters 1 and 4 (P = .02). A postoperative PASS score of 60 was achieved by all patients in cluster 3, by 86% of patients in cluster 2, by 63% of patients in cluster 1, and by 20% of patients in cluster 4. The differences between the groups were statistically significant (P = .01).

Conclusion

Arthroscopic surgery yielded good results in the treatment of stable borderline hip dysplasia with anterolateral and lateral deficiency. In contrast, borderline hip dysplasia with acetabular retroversion showed no improvements after arthroscopic therapy. This study underlines the need for an accurate analysis of all possible radiological signs to adequately classify borderline dysplastic hips.

Pelvic Bone Deformity and Its Correlation with Acetabular Center-edge Angle

Objective  The purpose of the present study was to evaluate the pelvic bone deformities and its correlation with the acetabular center-edge (CE) angle. Methods  Between August 2014 and April 2015, we prospectively evaluated patients aged between 20 and 60 years old. The exclusion criteria were: metabolic disease, previous hip or spine surgery, radiograph showing hip arthrosis ≥ Tönnis two, severe hip dysplasia, global acetabular overcoverage, acetabular crossover sign, hip deformities from slipped capital femoral epiphysis (SCFE) or Leg-Perthes-Calveé, and bad quality radiographs. At anteroposterior (AP) pelvic radiographs, we have evaluated: the CE angle, the acetabular index (IA), the acetabular crossover sign, the vertical and horizontal superior and inferior pelvic axis (H1: Horizontal line 1, superior pelvic axis; H2: Horizontal line 2, superior pelvic axis; V1: Vertical line, superior pelvic axis; HR: Horizontal line, inferior pelvic axis; VR: Vertical line, inferior pelvic axis). The superior and inferior pelvic axis were considered asymmetric when there was a difference ≥ 5 mm between both sides. Patients were divided into two groups: control and group 1. Results  A total of 228 patients (456 hips) were evaluated in the period. According to the established criteria, 93 patients were included. The mean age was 39.9 years old (20 to 60 years old, standard deviation [SD] = 10,5), and the mean CE angle in the right hip was 31.5° (20 ^o to 40°), and in the left 32.3° (20 ^o to 40°). The control group had 38 patients, with asymmetric H1 in 4 cases (10.5%), H2 in 5 (13.1%), V1 in 7 (18.4%), HR in 5 (13.1%) and VR in 1 (2.63%). Group 1 had 55 patients, with asymmetric H1 in 24 cases (43.6%), H2 in 50 (90.9%), V1 in 28 (50.9%), HR in 16 (29.09%) and VR in 8 (14.5%). Comparing both groups, there was statistical significance for H1, H2 and V1 asymmetry ( p  < 0.001). Conclusion  In the present paper, we observed the correlation between variation in the acetabular CE angle and asymmetry of the superior hemipelvis. The present authors believe that a better understanding of the pelvic morphologic alterations allows a greater facility in the diagnosis of hip articular deformities.

Elephant's ear sign: a new radiographic finding indicative of acetabular retroversion

Acetabular retroversion is a relatively common condition affecting the hip that can result in symptoms in some patients. Diagnosis of acetabular retroversion relies on obtaining a proper anteroposterior radiograph of the pelvis. Cross-over, posterior wall, and ischial spine signs are usually present in patients on the radiographs of patients with acetabular retroversion. In this illustrative case report, we describe an additional radiographic sign, elephant’s ear sign, associated with acetabular retroversion that we have seen to be present in patients with acetabular retroversion. A review of 26 acetabular retroversion case series by 2 independent reviewers showed 100% consensus on the presence of elephant’s ear sign in patients with evidence of all other radiographic signs of this hip abnormality. This simple and previously unreported radiographic Elephant’s ear sign, in which flared iliac wings appear as elephant’s ears, highlights the presence of acetabular retroversion.

Non-surgical interventions for excessive anterior pelvic tilt in symptomatic and non-symptomatic adults: a systematic review

Excessive anterior pelvic tilt is suspected of causing femoroacetabular impingement, low back pain, and sacroiliac joint pain. Non-surgical treatment may decrease symptoms and is seen as an alternative to invasive and complicated surgery. However, the effect of non-surgical modalities in adults is unclear. The aim of this review was to investigate patient- and observer-reported outcomes of non-surgical intervention in reducing clinical symptoms and/or potential anterior pelvic tilt in symptomatic and non-symptomatic adults with excessive anterior pelvic tilt, and to evaluate the certainty of evidence.

MEDLINE, EMBASE, Web of Science and Cochrane (CENTRAL) databases were searched up to March 2019 for eligible studies. Two reviewers assessed risk of bias independently, using the Cochrane Risk of Bias tool for randomized trials and the ROBINS-I tool for non-randomized studies. Data were synthesized qualitatively. The GRADE approach was used to assess the overall certainty of evidence.

Of 2013 citations, two randomized controlled trials (RCTs) (n = 72) and two non-RCTs (n = 23) were included. One RCT reported a small reduction (< 2°) in anterior pelvic tilt in non-symptomatic men. The two non-RCTs reported a statistically significant reduction in anterior pelvic tilt, pain, and disability in symptomatic populations. The present review was based on heterogeneous study populations, interventions, and very low quality of evidence.

No overall evidence for the effect of non-surgical treatment in reducing excessive anterior pelvic tilt and potentially related symptoms was found. High-quality studies targeting non-surgical treatment as an evidence-based alternative to surgical interventions for conditions related to excessive anterior pelvic tilt are warranted.

Cite this article: EFORT Open Rev 2020;5:37-45. DOI: 10.1302/2058-5241.5.190017

Does pain and hip function improve 2 years after reverse periacetabular osteotomy? A follow-up study of 74 patients

Data on outcome in patients with acetabular retroversion (AR) treated with reverse periacetabular osteotomy (reverse PAO) are sparse. The aim of the study was to investigate changes in pain and hip function among patients with AR 2 years after reverse PAO and to examine whether changes in pain were associated with changes in hip function. In addition, to evaluate patient satisfaction and changes in quality of life (QoL). We present a prospective follow-up study with patient-reported outcome data from Aarhus University Hospital in Denmark. Pain at rest and during activity was measured with a Visual Analogue Scale (VAS), hip function with the Hip disability and Osteoarthritis Outcome Score (HOOS) and QoL with the Short-Form 36, pre-operatively and 2 years after reverse PAO in 74 patients. Changes were analysed using paired t-test and multiple linear regressions. Significant and clinically relevant mean improvements in pain and hip function were found. The numbers of responders achieving a minimal clinically important difference varied from 51 to 73%. Positive significant association between changes in pain and changes in hip function were found. Significant mean improvement in QoL was found. The study had a loss to follow-up of 23%. Two years after reverse PAO, patients diagnosed with AR showed significant and clinically relevant mean improvements in pain and hip function. Decreased pain was significantly associated with improved hip function. The majority of patients were satisfied with the result of surgery and QoL was similar to the Danish background population.

Glossary of terms for musculoskeletal radiology

Members of the International Skeletal Society compiled a glossary of terms for musculoskeletal radiology. The authors also represent national radiology or pathology societies in Asia, Australia, Europe, and the USA. We provide brief descriptions of musculoskeletal structures, disease processes, and syndromes and address their imaging features. Given the abundance of musculoskeletal disorders and derangements, we chose to omit most terms relating to neoplasm, spine, intervention, and pediatrics. Consensus agreement was obtained from 19 musculoskeletal radiology societies worldwide.

The clinical presentation, diagnosis and pathogenesis of symptomatic sports-related femoroacetabular impingement (SRFAI) in a consecutive series of 1021 athletic hips

AIM

To examine the pathogenesis and clinical presentation of sports-related femoroacetabular impingement (SRFAI) in a large consecutive series of symptomatic athletes.

METHODS

Between January 2009 and February 2017 prospectively collected data from competitive athletes within the Gaelic Athletic Association (GAA), and who subsequently underwent arthroscopic treatment for symptomatic FAI, were analysed. Data was collected using internationally validated health questionnaires (Harris Hip Score, UCLA, SF-36, WOMAC) and recognised clinical (ROM, symptom presentation, provocation tests) and radiological (AP pelvis, Dunn, False profile) indicators/measures of FAI.

RESULTS

A total of 1021 consecutive cases (mean 26.6 ± 6.2 years) were included. In every case, conservative treatment failed to resolve symptoms with athletes attending an average of 2.4 ± 1.1 health care professionals prior to referral. Symptoms developed gradually (78%) and consisted primarily of groin pain (76.1%) and hip stiffness (76.5%) following activity. An acetabular rim deformity (pincer) was present in all cases; a cam deformity in 72.1%. The prevalence and degree of cam deformity increased with progressing age groups (p < 0.001); mean lateral centre-edge angle remained static (p = 0.456). Increasing CEA, alpha angle and presence of rim fracture was associated with a reduction in all ranges of hip movement (p < 0.001).

CONCLUSION

Symptomatic SRFAI presented in this large series of GAA athletes failed to resolve with non-operative treatment. Increasing hip deformity resulted in poorer ROM. Abnormal acetabular morphology remains static with increasing athletic age while cam deformity is progressive and most likely a secondary pathology.

Acetabular coverage differs between standing and supine positions: model-based assessment of low-dose biplanar radiographs and comparison with CT

OBJECTIVES

To evaluate the feasibility of 2D and 3D acetabular coverage assessments based on low-dose biplanar radiographs (BPR) in comparison with CT, and to demonstrate the influence of weight-bearing position (WBP) on anterior and posterior acetabular coverages.

METHODS

Fifty patients (21 females, 29 males) underwent standing BPR and supine CT of the pelvis. Using dedicated software, BPR-based calculations of anterior and posterior 2D coverages and anterior, posterior, and global 3D coverages were performed in standardized anterior pelvic plane (APP) and WBP. CT-based anterior and posterior 2D coverages and global 3D coverage was calculated in APP and compared with BPR-based data. Statistics included intraclass correlation coefficients (ICC) and Bland-Altman plots.

RESULTS

Mean anterior 2D coverage was 21.2% (standard deviation, ± 7.4%) for BPR and 23.8% (± 8.4%) for CT (p = 0.226). Mean posterior 2D coverage was 54.2% (± 9.8%) for BPR and 61.7% (± 9.7%) for CT (p = 0.001). Mean global 3D coverage was 46.5% (± 3.0%) for BPR and 45.6% (± 3.6%) for CT (p = 0.215). The inter-method reliability between CT and BPR and inter-reader reliability for BPR-based measurements were very good for all measurement (all ICC > 0.8). Based on BPR, mean anterior and posterior 3D coverages were 20.5% and 26.0% in WBP and APP, while 25 patients increased anterior and 24 patients increased posterior 3D coverage from APP to WBP with a relative change of coverage of up to 11.9% and 10.0%, respectively.

CONCLUSIONS

2D and 3D acetabular coverages can be calculated with very good reliability based on BPR. The impact of standing position on acetabular coverage can be quantified with BPR on an individual basis.

KEY POINTS

• 2D and 3D acetabular coverages can be calculated with very good reliability based on biplanar radiographs in comparison with CT. • The impact of standing position on anterior and posterior acetabular coverages can be quantified with BPR on an individual basis.

Radiographic signs of acetabular retroversion using a low-dose slot-scanning radiographic system (EOS®)

INTRODUCTION

Acetabular retroversion is assessed using pelvic X-ray. Cross-over-sign (COS), posterior-wall-sign (PWS) and ischial-spine-sign (ISS) are important radiographic signs of the condition. The pelvic area is sensitive to radiation and thus, possibilities to reduce dose should be considered. The purpose was to compare radiographic signs of acetabular retroversion on conventional pelvic anteroposterior (AP) X-rays with a low-dose slot-scanning system (EOS) in a sample of patients with retroversion of the acetabulum and to compare the radiation doses.

METHODS

34 participants with radiographic signs of acetabular retroversion in one or both hips on conventional pelvic X-ray were consecutively recruited. Pelvic EOS-images were acquired in each patient and COS, PWS, ISS, COS-ratio and PWS-ratio was assessed. Radiation dose comparison of X-ray vs. EOS was performed using Dose-Area Products.

RESULTS

Retroversion was present in 57 out of 68 hips. The absolute agreement was 91%, 84% and 76% for COS, PWS and ISS, respectively. No statistically significant differences were present between COS-ratio and PWS-ratio in either modality and Bland-Altman limits of agreement were narrow. The mean radiation dose was 1053 mGy*cm² in X-ray and 593 mGy*cm² in EOS (p = 0.003).

CONCLUSION

The results indicate that pelvic EOS provides diagnostic qualities similar to conventional X-ray using 44% less radiation when radiographic signs of acetabular retroversion are assessed.

Exercise Therapy for the Management of Femoroacetabular Impingement Syndrome: Preliminary Results of Clinical Responsiveness

OBJECTIVE

To investigate the responsiveness to exercise therapy of patients with femoroacetabular impingement syndrome (FAIS), and to investigate differences in hip function, strength, and morphology between responders versus nonresponders.

METHODS

Patients with FAIS underwent 12 weeks of semi-standardized and progressive exercise therapy. A good therapy outcome (responders) versus a poor therapy outcome (nonresponders) was determined at week 18 with the Global Treatment Outcome questionnaire for hip pain. Hip function was evaluated using the Hip Outcome Score (HOS) activities of daily living (ADL) and Sport at baseline, and at weeks 6, 12, and 18. Hip muscle strength and dynamic pelvic control were evaluated using dynamometry and video analysis, respectively, at baseline, week 12, and week 18. Hip morphology was evaluated with imaging at baseline.

RESULTS

Thirty-one patients (mean age 24 years) were included. Sixteen patients (52%) were responsive and 15 patients (48%) were not responsive to exercise therapy. Only responders improved HOS ADL and HOS Sport by 10 points (95% confidence interval [95% CI] 7, 14; P < 0.001) and by 20 points (95% CI 15, 25; P < 0.001), respectively, and hip abductor strength by 0.27 Nm/kg (95% CI 0.18, 0.36; P < 0.001). The prevalence of patients showing good dynamic pelvic control only increased in responders (44%; P = 0.029). The prevalence of severe cam morphology was higher in nonresponders than in responders (40% versus 6%; P = 0.037).

CONCLUSION

Half of patients with FAIS benefit from exercise therapy in the short term. Responsiveness to hip abductor strength and dynamic pelvic control improvements is associated with a good therapy outcome, whereas the presence of severe cam morphology is associated with a poor therapy outcome.

Acetabular Retroversion Is a Risk Factor for Less Optimal Outcome After Femoroacetabular Impingement Surgery

BACKGROUND

Patients with acetabular retroversion are at risk of labral tear and hip pain. It is unknown whether femoroacetabular osteoplasty (FAO) without reverse periacetabular osteotomy can be used in these patients. This study evaluated the outcome of mini-open FAO in patients with acetabular retroversion and compared that to patients without acetabular retroversion.

METHODS

Fifty-one patients (29 male, 22 female) with acetabular retroversion who had undergone FAO between 2007 and 2015 were identified. The minimum 2-year clinical and radiological outcome was compared with 550 patients without dysplasia or retroversion who underwent FAO by the same surgeon. The preoperative and postoperative alpha angle, center-edge angle, Tonnis grade, joint space, and presence of labral tear and chondral lesion were determined.

RESULTS

The mean age in the retroversion cohort was 27.4 ± 9.5 years compared to 34.5 ± 11.2 years in the control. The mean follow-up was 4.8 ± 1.5 years for retroversion and 4.1 ± 1.2 years for the control. The mean preoperative Short-Form 36 Health Survey and modified Harris hip score were not different between the cohorts. At the latest follow-up, the mean modified Harris hip score and Short-Form 36 Health Survey were significantly lower in the retroversion group (75.4 and 76.5) compared to the control (83.4 and 85.6). There was a higher percentage of failure among retroversion patients (13.7%) compared to the control (2.5%).

CONCLUSION

Acetabular retroversion resulting in femoroacetabular impingent may be treated by FAO, but the outcome appears to be less optimal compared to patients with femoroacetabular impingent and no evidence of dysplasia and acetabular retroversion. Hip preservation surgeons should be aware of this anatomic variation and possible inferior treatment results after FAO in these patients.

Is MRI an adequate replacement for CT scans in the three-dimensional assessment of acetabular morphology?

BACKGROUND

Appropriate three-dimensional imaging of the hip joint is a substantial prerequisite for planning and performing surgical correction of deformities. Although surgeons still use computed tomography (CT), modern and fast acquisition techniques of volumetric imaging using magnetic resonance imaging (MRI) for pelvic measurements enable similar resolution.

PURPOSE

This study was designed to determine if already described measures of acetabular morphology are comparable in both techniques and if assessment can be performed with equal intra-observer and inter-observer reliability.

MATERIAL AND METHODS

Thirty-two hips (16 patients) were examined with a pelvic CT and a MRI with 3-T. Pelvic orientation was standardized by each observer in coronal, axial, and sagittal planes. Acetabular version as well as seven acetabular sector angles were measured by two observers twice with a minimum of four weeks between sessions.

RESULTS

Inter-rater reliability showed excellent results for intra- and inter-rater reliability for CT (0.977-0.999) and MRI (0.969-0.998) measuring acetabular version and sector angles. Evaluating the reliability of CT and MRI for each observer revealed excellent results (0.972-0.998). Evaluating the Bland-Altman plots for intra-observer reliability showed an equal distribution of angles, within acceptable 95% limits of agreement. The same results were observed for inter-observer reliability evaluating CT and MRI as well as inter-method reliability.

CONCLUSION

Modern MRI scans are equally applicable to assess the bony pelvis as CT scans. In addition, MRI would enable the examination of soft tissues such as chondrolabral structures and muscle in the same examination. Since hip-preserving surgery is mostly conducted in younger patients, the reduction of radiation exposure is a benefit.

"Simple mechanical devices did not improve pelvis positioning in AP pelvis radiographs for reliable assessment of the acetabular orientation"

BACKGROUND

The aim of this study was to develop two simple positioning devices for anteroposterior pelvis radiographs and to evaluate their effect on accuracy of the radiographs for assessment of the acetabular orientation compared with non-instrumented positioning.

METHODS

The superior anterior iliac spines and the pubic symphysis were used as anatomical landmarks to obtain a horizontal orientation of the pelvis according to the anterior pelvic plane. Anteroposterior pelvis radiographs were taken of 11 human cadaveric pelvic bones with each of the positioning devices and without any device. Defined measurements were carried out to objectify the tilt and rotation of the pelvis and to assess the cross-over sign as well as the presence of the ischial spine sign. Computed tomography scans were performed as a standard of reference. Bland-Altman-Plots were used to compare the continuous measurement values and Cohen's Kappa was applied for the categorical data. Intra- and inter-observer reliability was determined by the intraclass correlation coefficient and Cohen's Kappa.

RESULTS

The mean values of the measurements showed a high variability. A low correlation of the measurement values was found between the radiographs of the different positioning methods and the computed tomography scans. The intra- and inter-observer reliability was good (Cohen's Kappa 0.78 and 0.69; intraclass correlation coefficient 0.99 and 0.98).

CONCLUSION

The use of positioning devices did not lead to more accurate anteroposterior pelvis radiographs compared to non-instrumented positioning. Simple positioning devices do not provide standardized anteroposterior pelvis radiographs for reliable assessment of the acetabular orientation.

Hip Radiograph Findings in Patients Aged 40 Years and Under with Posterior Pelvic Pain

BACKGROUND

Several sacroiliac joint (SIJ) provocative tests used to assess posterior pelvic pain involve moving and stressing the hip. It is unknown if there is a subgroup of patients with posterior pelvic pain who have underlying hip deformity that could potentially influence performance and interpretation of these tests.

OBJECTIVE

To describe the prevalence of radiographic hip deformity and hip osteoarthritis in a group of adults 40 years old and under who met the clinical diagnostic criteria for treatment of posterior pelvic pain with an image guided intra-articular SIJ injection.

DESIGN

Retrospective cohort study.

SETTING

Tertiary university orthopedic department PATIENTS (OR PARTICIPANTS): One hundred and forty-eight patients were evaluated (83% (123/148) female; mean age 31.3 ± 6.2 years). All had completed a trial of comprehensive noninvasive treatment for posterior pelvic pain and had a minimum of three positive SIJ provocative tests on physical examination.

METHODS

Retrospective review identified patients undergoing SIJ injection for pain recommended and performed by seven physiatrists between 2011 and 2017. Hip radiographs were read by a physician with expertise in hip measurements with previously demonstrated excellent intrarater reliability.

MAIN OUTCOME MEASUREMENTS

Percentage of patients with hip deformity findings.

RESULTS

No patients meeting the inclusion criteria had significant radiographic hip osteoarthritis (Tonnis ≥2 indicating moderate or greater radiographic hip osteoarthritis) and 4/148 (3%) were found to have mild radiographic hip osteoarthritis. Prearthritic hip disorders were identified in 123 (83%, 95% CI: 76, 89%) patients. For those patients with prearthritic hip disorders, measurements consistent with femoroacetabular impingement (FAI) were seen in 61 (41%) patients, acetabular dysplasia in 49 (33%) patients, and acetabular retroversion in 85 (57%) patients. Acetabular retroversion was identified in 43% (crossover sign) and 39% (prominent ischial spine) of patients.

CONCLUSIONS

Approximately 57% of adult patients under the age of 40 years with the clinical symptom complex of SIJ pain were found to have radiographic acetabular retroversion. This is a higher percentage than the 5%-15% found in asymptomatic people in the current literature. Further study is needed to assess links between hip structure, hip motion, and links to pelvic pain including peri and intra-articular SIJ pain.

LEVEL OF EVIDENCE

III.

Femoroacetabular Impingement in Pediatric Patients

Subacute, nontraumatic hip pain is often a diagnostic challenge. Femoroacetabular impingement (FAI) is a common cause of atraumatic hip pain that is poorly understood. FAI is a result of abnormal morphologic changes in either the femoral head or the acetabulum. FAI is more prevalent in people who perform activities requiring repetitive hip flexion, but it remains common in the general population. Evaluation begins with physical examination maneuvers to rule out additional hip pathology and provocation tests to reproduce hip pain. Diagnosis is often made by radiography or magnetic resonance imaging. Initial treatment is generally more conservative, featuring activity modification and physical therapy, whereas more aggressive treatment requires operative management.

Location and Correlation of Acetabular Labral Tears and Paralabral Cysts Using Magnetic Resonance Imaging or Magnetic Resonance Arthrography in Patients With Femoroacetabular Impingement

PURPOSE

To evaluate the prevalence and location of paralabral cysts and the correlation between the type of femoroacetabular impingement (FAI) and acetabular labral tears, as well as the location of the paralabral cysts.

METHODS

Patients who received a diagnosis of FAI syndrome using plain radiography, magnetic resonance imaging or magnetic resonance arthrography, or computed tomographic arthrography from 2010 to 2015 were included in this study. The exclusion criteria were patients with arthritis (Tönnis grade 2 or greater) or dysplasia. We identified paralabral cysts and their location, size, configuration. Correlations between the type of FAI and labral tears and paralabral cysts were analyzed using the χ-square test.

RESULTS

Among 506 patients with FAI, paralabral cysts were found in 51 patients (55 hips) and were located anterosuperiorly in 40% of cases, posterosuperiorly in 36%, anteroinferiorly in 17%, and posteroinferiorly in 8%. We identified multilocular cysts in 60% of hips and unilocular cysts in 40%. Labral tears were radiographically found in 44 of 55 hips with paralabral cysts (80%); they were located anterosuperiorly in 59% and posterosuperiorly in 41%. Although paralabral cysts were found in the anteroinferior and posteroinferior areas, acetabular labral tears were not identified in the anteroinferior and posteroinferior areas. Classification of the type of FAI showed cam type in 14 of 55 hips (25.5%), pincer type in 16 (29%), mixed type in 7 (13%), labral tears in 15 (27%), and normal findings in 3 (5.5%). No correlation was found between the type of FAI and labral tears (P = .739) or the location of paralabral cysts (P = .228).

CONCLUSIONS

Paralabral cysts in patients with FAI most commonly are found in the anterosuperior area and are of the multilocular type. Although paralabral cysts in the anterosuperior and posterosuperior portions are related to labral tears, those in the anteroinferior and posteroinferior portions are not.

LEVEL OF EVIDENCE

Level IV, diagnostic case series.

Analysis of acetabular version: Retroversion prevalence, age, side and gender correlations

Introduction

Studies using conventional radiographical signs and computerized tomography (CT) for retroversion of the acetabulum have reported a prevalence of up to 25%. The purpose of this study was to provide a detailed report on acetabular version, gender, age and side differences in a large cohort.

Materials and methods

A total of 404 patients receiving a whole-body CT scan, aged between 16 and 40 years, have been included in the study. The measurement was performed in the transversal plane on three levels: cranial, central and caudal.

Results

The retroverted acetabulum on all three levels had a prevalence of 0.25% (95% confidence interval 0–0.7%). The average central anteversion in men was 16.46° (±4.42) and that in women was 19.31° (±5.04) (p < 0.001). Version increases with age, but a cluster analysis showed this to be a trend (p = 0.068).

Conclusion

Women have a higher average acetabular version than men. Retroversion in a young adult population has a low prevalence when measured with conventional CT. About a tenth of the population has a significantly different contralateral acetabular version.

The translational potential of this article

Global acetabular retroversion has a much lower prevalence than previously reported.

Computer-assisted anteverting eccentric rotational acetabular osteotomy for recurrent posterior dislocation associated with acetabular retroversion: a case report

Background

Acetabular retroversion is a rotatory abnormality of the entire hemipelvis that includes anterior over-coverage and posterior deficiency of the acetabulum, and is associated with pincer-type femoroacetabular impingement and posterior hip instability. Acetabular retroversion is thought to cause posterior dislocation of the hip in athletes due to both the pincer-type femoroacetabular impingement and posterior hip instability.

Case presentation

A 26-year-old Japanese man had acetabular retroversion that induced recurrent posterior dislocation of his hip due to excessive hip flexion while wakeboarding. We performed anteverting eccentric rotational acetabular osteotomy using preoperative three-dimensional planning and an intraoperative computerized navigation system. Our patient was able to return to sports activities 1 year postoperatively.

Conclusions

Both preoperative three-dimensional surgical planning software and an intraoperative navigation system can provide a highly accurate map for this complicated surgery that simultaneously improves the pincer-type femoroacetabular impingement and posterior deficiency of the acetabulum.