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.

1450 Relationship between Spinopelvic Parameters and Symptomatic Femoroacetabular Impingment: A Scoping Review

Aim Reports have shown that spinopelvic mobility influences the outcome following total hip arthroplasty. The aim of this scoping review was to investigate the relationship between spinopelvic parameters (SPP) and symptomatic femoroacetabluar impingement (FAI). Method A systematic computer search of EMBASE, PubMed and Cochrane for literature related to SPPs and FAI was undertaken as per PRISMA guidelines. Clinical outcome studies and prospective/retrospective studies that investigated the role of SPPs in symptomatic FAI were included. Review articles, case reports and book chapters were excluded. Information extracted pertained to symptomatic cam deformities, pelvic tilt, deviations in acetabular version, decreases in pain-free hip range of motion (ROM) on dynamic hip movements and radiological signs of FAI. Results The literature search identified 46 papers out of 1168 investigating the link between SPPs and pathological processes characteristic of FAI. Anteior pelvic tilt was associated with radiographic over-coverage parameters of FAI. Three studies associated FAI pathology with a greater pelvic incidence (PI), while four associated it with a smaller PI. In dynamic movements, decreased posterior pelvic tilt and reduced saggital pelvic ROM was found in symptomatic FAI patients during hip flexion. Conclusions Our study shows that spinopelvic parameters can influence radiological and clinical manifestations of FAI, with pelvic incidence, acetabular version and muscular imbalances being aetiologically implicated. Individual spinopelvic mobility may predispose to the development of FAI, which may be amenable to non-surgical management. If FAI pathoanatomy already exists however, sagittal pelvic parameters can influence whether FAI symptoms develop, and the extent to which they do so.

1300 Version Abnormalities of the Femur and Acetabulum in Patients with Femoroacetabular Impingement: A Systematic Review

Aim This systematic review aims to understand the relationship between version abnormalities of the femur and acetabulum in patients with primary and secondary femoroacetabular impingement (FAI). Method A systematic review was conducted according to PRISMA guidelines. A computer-based search was performed using the EMBASE, MEDLINE, PubMed and Cochrane databases for articles relating to version and torsional abnormalities in FAI, Legg-Calve-Perthes disease (LCPD) and slipped capital femoral epiphysis (SCFE). The study was registered in the Open Science Framework. Two authors independently performed title/abstract and full text screening according to predetermined inclusion criteria. Results A total of 1206 articles were identified 55 articles, involving 10, 091 hips, met the inclusion criteria. All studies evaluating femoral/acetabular version in FAI reported ‘normal’ mean version values (10o to 25o). However, distribution analysis revealed that an estimated 31.4% and 51.3% of patients with FAI displayed abnormal acetabular and femoral version, respectively. Abnormal femoral version was reported in an estimated 74.5% of hips with LCPD, and abnormal acetabular version in an estimated 20%. Acetabular version was significantly lower in hips with SCFE compared to controls (Z=-3.26, P &lt; 0.01). Conclusions Patients presenting with hip pain attributed to FAI are likely to display an abnormality in femoral or acetabular version. This highlights the importance of evaluating these parameters during assessment of these patients, in order to guide clinical decision making.

Over one third of patients with symptomatic femoroacetabular impingement display femoral or acetabular version abnormalities

Purpose The aim of this study was investigate the relationship between version and torsional abnormalities of the acetabulum, femur and tibia in patients with symptomatic FAI. Methods A systematic review was performed according to PRISMA guidelines using the EMBASE, MEDLINE, PubMed and Cochrane databases. Original research articles evaluating the described version and torsional parameters in FAI were included. The MINORS criteria were used to appraise study quality and risk of bias. Mean version and torsion values were displayed using forest plots and the estimated proportion of hips displaying abnormalities in version/torsion were calculated. Results A total of 1206 articles were identified from the initial search, with 43 articles, involving 8861 hips, meeting the inclusion criteria. All studies evaluating femoral or acetabular version in FAI reported ‘normal’ mean version values (10–25 °). However, distribution analysis revealed that an estimated 31% and 51% of patients with FAI displayed abnormal central acetabular and femoral version, respectively. Conclusion Up to 51% of patients presenting with symptomatic FAI show an abnormal femoral version, whilst up to 31% demonstrate abnormal acetabular version. This high percentage of version abnormalities highlights the importance of evaluating these parameters routinely during assessment of patients with FAI, to guide clinical decision-making. Level of evidence IV.

THREE-DIMENSIONAL PREDICTORS OF FAI DISEASE PROGRESSION IN THE CONTRALATERAL HIP

Background: Bony morphologies contributing to femoroacetabular impingement (FAI) are relatively common in the general population, but drivers of symptom development are not well understood. Hypothesis/Purpose: The purpose of this study was to determine the role of three-dimensional bony morphology in symptom development in the contralateral hip in patients undergoing ipsilateral surgical treatment for FAI. Methods: The study included a prospective cohort of 161 consecutive patients (101 females, 60 males) who presented for ipsilateral FAI surgical treatment from 2013-2018. The average age was 29.1 years. Minimum follow-up was 1 year (mean, 2.3 years; range, 1-6 years). Low-dose CT scans were obtained prior to surgical treatment. Three-dimensional hip analysis of the contralateral hip was performed relative to normative data and allowed measurements of 15 key parameters. Prior to surgery and at routine follow-up, patients completed standardized questionnaires that included pain in the contralateral hip. Univariate and multivariate analyses were performed to identify independent predictors. Results: There were 133 patients (83%) with follow-up. Significant levels of pain in the contralateral hip were reported in 25 (18.8%) patients at presentation and 50 (35.3%) patients at follow-up. Twenty-six (19.5%) patients progressed to surgery at an average of 1.12 years. Significant predictors of symptom development were alpha angle >55° at 1:00 (p=0.037), femoral version <0° or > 20° (p=0.027), and decreased central acetabular version at 3:00 (p=0.048). Significant predictors of surgery were age <30 years (p=0.023) and alpha angle >55° at 1:00 (p=0.005). Conclusion: We found that roughly 1 in 5 patients undergoing surgical treatment for ipsilateral FAI experienced pain in the contralateral hip at presentation, over one third reported pain at follow-up, and 1 in 5 progressed to surgery. Higher alpha angle, abnormal femoral version, and decreased acetabular version were correlated with symptom development, while higher alpha angle and age under 30 were associated with progression to surgery.

SLIPPED CAPITAL FEMORAL EPIPHYSIS ACETABULAR ORIENTATION AND SHAPE: A THREE-DIMENSIONAL CT STUDY

Background: Previous studies have analyzed the acetabulum in patients affected by slipped capital femoral epiphysis (SCFE), however controversy remains over how the acetabular shape may be altered in hips experiencing SCFE. In particular, changes in acetabular over-coverage and acetabular version are thought to contribute to SCFE. Hypothesis/Purpose: The purpose of this study was to determine the acetabular morphology in hips with SCFE and compare them to normally developing children. Methods: Images from patients with the diagnosis of SCFE who had a computed tomography (CT) exam of their pelvis were compared to images from an age- and sex-matched cohort of patients with CT exams of the pelvis/abdomen for a non-orthopedic related evaluation (controls). Three dimensional (3D) reconstructions were created from each CT exam (MIMICs software). Custom MATLAB software was used to uniformly align and calculate acetabular parameters from the 3D reconstructions. The acetabular parameters calculated were articular surface area, acetabular tilt, acetabular version, and acetabular coverage angles measured in a radial fashion in 5 out of 8 octants. Results: Two-hundred-ninety-eight hips were evaluated, including 67 hips with SCFE, 39 unaffected contralateral hips in patients with SCFE, and 192 normal controls. The SCFE group consisted of 33 males and 34 females. Acetabular version was similar amongst all SCFE affected hips, unaffected contralateral hips, and normal controls (p=0.575). Control hips had higher acetabular tilt than SCFE affected hips (p=0.001) and unaffected contralateral hips (p=0.012). Acetabular surface area was higher in SCFE affected hips compared to controls (p=0.003)(Table 1). SCFE affected hips had significantly increased acetabular coverage compared to controls in the superior, superior-anterior, and anterior octants (p<0.01). The unaffected contralateral sides had significantly increased acetabular coverage compared to controls in all five regions (p<0.02)(Table 2). Conclusions: Contrary to some previous studies, we did not find the acetabulum to be retroverted in hips with SCFE compared to normal hips. Both the affected and unaffected hips of SCFE patients have decreased acetabular tilt. Acetabular surface area is high in both the affected and unaffected sides in SCFE, suggesting it may be involved in the pathogenesis of the condition. There is increased acetabular coverage in the superior regions of SCFE hips. The shared morphological characteristics of both affected and unaffected sides in SCFE patients suggest that their hip anatomy may predispose them to slips. [Table: see text][Table: see text]

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