Anterior coverage after eccentric rotational acetabular osteotomy for the treatment of developmental dysplasia of the hip

Which hip morphology measures and patient factors are associated with age of onset and symptom severity in femoroacetabular impingement syndrome?

BACKGROUND

Bony morphology is central to the pathomechanism of femoroacetabular impingement syndrome (FAIS), however isolated radiographic measures poorly predict symptom onset and severity. More comprehensive morphology measurement considered together with patient factors may better predict symptom presentation. This study aimed to determine the morphological parameter(s) and patient factor(s) associated with symptom age of onset and severity in FAIS.

METHODS

99 participants (age 32.9 ± 10.5 years; body mass index (BMI 24.3 ± 3.1 kg/m²; 42% females) diagnosed with FAIS received standardised plain radiographs and magnetic resonance scans. Alpha angle in four radial planes (superior to anterior), acetabular version (AV), femoral torsion, lateral centre-edge, anterior centre-edge (ACEA) and femoral neck-shaft angles were measured. Age of symptom onset (age at presentation minus duration of symptoms), international Hip Outcome Tool-33 (iHOT-33) and modified UCLA activity scores were recorded. Backward stepwise regression assessed morphological parameters and patient factors (age, sex, BMI, symptom duration, annual income, private/public healthcare system accessed) to determine variables independently associated with onset age and iHOT-33 score.

RESULTS

Earlier symptom onset was associated with larger superoanterior alpha angle (p = 0.007), smaller AV (p = 0.023), lower BMI (p = 0.010) and public healthcare system access (p = 0.041) (r² = 0.320). Worse iHOT-33 score was associated with smaller ACEA (p = 0.034), female sex (p = 0.040), worse modified UCLA activity score (p = 0.010) and public healthcare system access (p < 0.001) (r² = 0.340).

CONCLUSIONS

Age of symptom onset was chiefly predicted by femoral and acetabular bony morphology measures, whereas symptom severity predominantly by patient factors. Factors measured explained a small amount of variance in the data; additional unmeasured factors may be more influential.

Determining anterior hip coverage in patients with hip dysplasia using the anterior center-edge angle on Lequesne's false-profile radiograph and on computed tomography

Anterior hip coverage is important for hip stability. As a parameter of anterior hip coverage, the anterior center-edge angle on false-profile radiograph (ACEA FP) is associated with clinical outcomes. With the widespread application of computed tomography (CT), the anterior center-edge angle on CT (ACEA CT) has also been used to measure anterior hip coverage. Little is known about the reproducibility of the ACEA FP and ACEA CT in patients with hip dysplasia or the correlation between the ACEA CT and ACEA FP. In total, 49 hips of 49 patients who underwent periacetabular osteotomy in our center were included. The lateral center-edge angle, Tönnis angle, ACEA FP and ACEA CT were determined. We assessed the intraobserver and interobserver reliability of the ACEA FP and ACEA CT, the effect of the Tönnis angle on the reliability of the ACEA FP and ACEA CT and the correlation between the ACEA CT and ACEA FP. The intraobserver and interobserver interclass correlation coefficients of the ACEA FP were good, and those of the ACEA CT were very good. The Tönnis angle was weakly correlated with inconsistent ACEA FP measurements (P = 0.008) but not with inconsistent ACEA CT measurements (P = 0.600). No correlation between ACEA FP and ACEA CT measurements was observed (P = 0.213-0.665). The reproducibility of the ACEA CT is more consistent than that of the ACEA FP. The oblique acetabular roof had an effect on determining the ACEA FP but not on determining the ACEA CT. No correlation was observed between the measured ACEA FP and ACEA CT values, so the clinical evidence obtained from the ACEA FP cannot be directly applied to the ACEA CT.

Evaluation of Anterior Coverage in Children With Developmental Dysplasia of the Hip Using Transverse Magnetic Resonance Imaging at 2 Years Is Predictive of Future Radiographic Coverage

BACKGROUND

Although normal anterior acetabular coverage provides stability to the hip, acetabular retroversion leads to femoroacetabular impingement related to hip osteoarthritis. Previous studies have focused on acetabular version and anteroposterior coverage in children with developmental dysplasia of the hip (DDH); however, the correlation between anteroposterior coverage and acetabular development is unclear. We measured anteroposterior acetabular coverage in DDH patients using transverse magnetic resonance imaging (MRI) and subsequent bony acetabular growth, and evaluated the correlation of those findings.

METHODS

We evaluated 37 DDH (dislocations) in 36 patients who underwent MRI at 2 years of age. The mean age was 2.2±0.3 years at the time of MRI (1.6±0.4 y after reduction) and 6.0±0.1 years at the time of plain radiography for the Severin classification. On MRI scans, we measured the cartilaginous center-edge angle (CCEA) and cartilaginous acetabular-head index (CAHI) in the coronal plane and the anterior and posterior cartilaginous center-edge angles (AC-CEA and PC-CEA, respectively) in the transverse plane. Severin I or II was defined as a good outcome and III or IV as a poor outcome.

RESULTS

In the evaluations conducted at 2 years of age, the mean CCEA, CAHI, AC-CEA, and PC-CEA were 14±9 degrees, 66%±10%, 39±8 degrees, and 77±7 degrees, respectively; the CEA at 6 years of age was 13±7 degrees. Twelve and 25 hips were classified in the good and poor outcome groups, respectively. Although CCEA, CAHI, and AC-CEA were significantly associated with the outcome in a single regression analysis ( P <0.05), only AC-CEA was significant in the multiple regression analysis with a stepwise selection method ( P =0.018). The cutoff AC-CEA value for a good outcome was 38 degrees (sensitivity, 67%; specificity, 68%) using a receiver operating characteristic curve.

CONCLUSIONS

Among MRI findings for acetabular cartilaginous morphology, AC-CEA was strongly associated with the outcome. Anteroposterior coverage was correlated with bony acetabular growth in childhood, and anterior coverage was particularly important for subsequent acetabular growth.

LEVEL OF EVIDENCE

Level IV-case series.

The Impact of the Laterality on Radiographic Outcomes of the Bernese Periacetabular Osteotomy

The purpose of this study was to compare the pre and postoperative radiographic findings and analyze the complication rate with respect to the laterality in periacetabular osteotomy in right-handed surgeons. Satisfaction rate and radiographic findings were prospectively collected between 2017 and 2019 and retrospectively reviewed. For analysis, all measurements of the CT scans were performed by a musculoskeletal fellowship-trained radiologist. Complications were classified into two categories: perioperative or postoperative. All surgeries were performed by three right-hand dominant hip surgeons. A total of 41 dysplastic hips (25 right and 16 left hips) in 33 patients were included. Postoperatively, a significantly lower acetabular index angle on the left side was observed at −2.6 ± 4.3 as compared to the right side at 1.6 ± 6.5 (p < 0.05). The change in Center edge (CE) angle was significantly lower for the left side 13.7 ± 5.5° than on the right side, measured at 18.4 ± 7.3 (p < 0.001); however, the overall CE angle was comparable at 38.5 ± 8.9° without any significant difference between the operated hips (left side at 37.8 ± 6.1° versus right side at 39.0 ± 10.3; p = 0.340). No significant differences in other radiographic measurements or surgical time were observed. For complications, the right side was more commonly affected, which may also explain a higher satisfaction rate in patients who were operated on the left hip with 92.3%. The change in lateral CE angle was significantly lower for the left side and the right hip seems to be predisposed to complications, which correlate with a lower satisfaction rate in right-handed surgeons.

Functional outcomes are preserved in adult acetabular dysplasia with radiographic evidence of lumbosacral spine anomalies: an investigation in hip-spine syndrome

Purpose

Acetabular dysplasia (AD) is a debilitating condition which results in impaired hip function, leading to hip-spine syndrome with anomalies identifiable on plain radiographs. However, no study to date has investigated the association between radiographic spine anomalies and functional outcomes in AD. We hypothesize that AD patients with radiographic evidence of lumbar spine anomalies are associated with decreased function in comparison to those without such radiographic findings.

Patients and methods

One hundred thirty-five hips underwent a full four-view hip radiograph series, and two observers analyzed hip and spine variables using standard radiographs and obtained Castellvi grade, assessment of spondylolisthesis, and L4-S1 interpedicular distance. A comprehensive hip questionnaire was administered which included Harris Hip Score (HHS) and Hip Disability and Osteoarthritis Outcome Score (HOOS) to assess patient function. Correlations between HHS and HOOS and radiographic spinal measurements were calculated, and p-values were corrected for multiple comparison using the Holm’s method.

Results

Out of 135 patients, 119 were female (88.1%) and 16 were male (11.9%). Average age of presentation was 34.2 years, and average BMI was 26. There was no statistically significant correlation between Castellvi grade, presence of spondylolisthesis, or L4-S1 interpedicular distance and the patient-reported outcome measures HHS or HOOS. Conversely, a significant correlation was observed between Femoro-Epiphyseal Acetabular Roof (FEAR) index and HOOS of the contralateral hip (correlation coefficient = 0.38, adjusted p = 0.03) and Tönnis angle of AD severity and HHS of the contralateral hip (correlation coefficient = − 0.33, adjusted p = 0.04).

Conclusion

Severity of spinal anomalies measured by Castellvi grade and spondylolisthesis in patients with AD was not associated with decreased patient function in the ipsilateral diseased hip. To our knowledge, this is the first study to date to report the relationship between radiographically identifiable lumbosacral abnormalities and hip function in AD.

Postoperative excessive anterior acetabular coverage is associated with decrease in range of motion after periacetabular osteotomy

PURPOSE

The aim of this study was to evaluate the relationship between acetabular 3-dimensional (3D) alignment reorientation and clinical range of motion (ROM) after periacetabular osteotomy (PAO).

METHODS

50 patients (58 hips) with hip dysplasia participated in the study and underwent curved PAO. The pre- and postoperative 3D centre-edge (CE) angles and femoral anteversion were measured and compared with clinical outcomes, including postoperative ROM.

RESULTS

The correlation between pre- and postoperative acetabular coverage and postoperative ROM was evaluated. Postoperative abduction and internal rotation ROM were significantly associated with postoperative lateral CE angles (abduction; p < 0.001, internal rotation; p = 0.028); flexion and internal rotation ROM was significantly associated with postoperative anterior CE angles (flexion; p < 0.001, internal rotation; p = 0.028). Femoral anteversion was negatively correlated with postoperative abduction (p = 0.017) and external rotation (p = 0.047) ROM.

CONCLUSION

Postoperative anterior acetabular coverage may affect internal rotation ROM more than the lateral coverage. Therefore, the direction of acetabular reorientation should be carefully determined according to 3D alignment during PAO.

Overcorrection of the acetabular roof angle or anterior center-edge angle may cause decrease of range of motion after curved periacetabular osteotomy

The aim of this study was to evaluate the relationship between the correction of radiographic parameters and clinical range of motion (ROM) after periacetabular osteotomy (PAO). Sixty-nine patients with hip dysplasia were enrolled and underwent curved PAO. The pre- and post-operative 3D center-edge (CE) angles, total anteversion (acetabular and femoral anteversion), and radiographic acetabular roof angle were measured and compared with the post-operative ROM. The aim of surgery was to rotate the central acetabular fragment laterally without anterior or posterior rotation. Multiple linear regression analysis demonstrated that post-operative internal rotation at 90° flexion was significantly associated with the post-operative Tönnis sourcil angle (rr = 0.31, P = 0.02) and that the post-operative ROM of flexion and internal rotation at 90° flexion were significantly associated with the anterior CE (flex; rr = -0.44, P = 0.001, internal rotation at 90° flexion; rr = -0.44, P < 0.001). However, we found no association between the lateral CE, femoral anteversion, or total anteversion and the post-operative ROM. We demonstrated that the overcorrection of the acetabular roof angle or anterior CE angle may cause a decrease in the range of motion after curved PAO. Therefore, surgeons need to be careful during surgery to prevent the overcorrection of the weight-bearing area and anterior acetabular coverage of the acetabular fragment to avoid femoroacetabular impingement after PAO.

Pelvic morphology medial to the femoral head center predicts anterior coverage and range of motion after curved periacetabular osteotomy

This study observed anterior coverage extent after lateral rotation of the acetabulum, without anterior or posterior rotation, during curved periacetabular osteotomy by three-dimensional simulation, and determined if preoperative pelvic morphology affects postoperative anterior coverage and range of motion. Thirty patients scheduled for consecutive primary curved periacetabular osteotomy for developmental hip dysplasia at our hospital between 2016 and 2017 were included. Virtual acetabular osteotomies were performed to achieve a postoperative lateral center-edge angle of 30°. We measured anterior center-edge angles before curved periacetabular osteotomy through the medial one-third and one-quarter of the femoral head as an index reflecting the pelvic morphology medial to the femoral head center. The range of motion simulation was performed after virtual curved periacetabular osteotomy. Single linear regression analysis was performed to examine correlations between preoperative pelvic morphology parameters and anterior center-edge angles after virtual osteotomy. Furthermore, linear regression analysis was used to assess correlations between center-edge angles and simulated range of motions (P < .05). Anterior center-edge angle after virtual osteotomy was more strongly correlated with the anterior center-edge angle through the medial one-third (r = .92, P < .0001) and one-quarter (r = .84, P < .0001) of the femoral head. Flexion angle and internal rotation at 90° flexion showed significant correlations with anterior center-edge angle through the medial one-third (r = -.62, P = .0003; r = -.57, P = .001) and one-quarter (r = -.60, P = .0005; r = -.55, P = .002) of the femoral head and anterior center-edge angle after virtual osteotomy (r = -.67, P = .0005; r = -.62, P = .0003). Measuring preoperative parameters reflecting pelvic morphology enables surgeons to predict postoperative anterior coverage and range of motion in curved periacetabular osteotomy cases.

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.

Incidence and determinants of anteflexion impairment after rotational acetabular osteotomy

This study aimed to identify the incidence of anteflexion impairment after rotational acetabular osteotomy based on patient-reported outcome measures, and the morphological factors and postoperative bony range of motion associated with anteflexion impairment at 2 years postoperatively. We analyzed 26 patients with developmental dysplasia of the hip who underwent rotational acetabular osteotomy at our institution. Using questionnaires, we defined anteflexion impairment as difficulty in clipping toenails and pulling up and removing socks. Morphological parameters and bony range of motion measured using a postoperative three-dimensional surface model, were compared between the subjects with and without anteflexion impairment. The incidence of anteflexion impairment was 69% at 6 months, 35% at 1 year, and 12% at 2 years after rotational acetabular osteotomy. The mean bony flexion angle was smaller in subjects with impairment than in those without impairment. The mean internal rotation (IR) angle at 90° of flexion was smaller in subjects with impairment than in those without impairment. The incidence of impairment was significantly higher in subjects with both less than or equal to 105° of bony flexion and less than or equal to 20° of IR at 90° of flexion than in the remaining subjects. No significant difference was observed in postoperative femoral head coverage and preoperative morphological parameters including spinal condition between the two groups. To prevent femoroacetabular impingement after rotational acetabular osteotomy, surgeons need to reorient the acetabulum to restore postoperative bony flexion to more than or equal to 105° and/or postoperative IR range of motion to more than or equal to 20° at 90° of flexion.

Outcomes of computer-assisted peri-acetabular osteotomy compared with conventional osteotomy in hip dysplasia

Aim of the study

To compare the outcomes after computer-assisted peri-acetabular osteotomy (PAO) and conventional PAO performed for hip dysplasia (DDH).

Methods

Ninety-one patients (98 hips) were enrolled in this study. In each case, DDH was treated with either conventional PAO, in which the angle and direction of the osteotomy was determined by intra-operative X-ray examination, or with computer-assisted PAO, which used the 3D navigation system. Forty hips underwent conventional PAO and 58 hips underwent computer-assisted PAO.

Results

Japanese Orthopaedic Association hip scores improved significantly from 70.0 points pre-operatively to 90.7 points post-operatively in patients with conventional PAO, and from 74.5 points pre-operatively to 94.2 points post-operatively in patients with computer-assisted PAO. In all patients with computer-assisted PAO, the post-operative AHI and VCA angle were within the radiographic target zone. Some patients with conventional PAO had post-operative AHI and VCA angle outside of the target zone. We performed total hip arthroplasty (THA) on five of the 98 PAO hips (5.1%) after an average follow-up period of 5.4 years. None of 58 hips (0%) with computer-assisted PAO was revised.

Discussion

Computer-assisted PAO enabled intra-operative confirmation of osteotomy sites, and the position of the osteotomized bone fragment could be confirmed in real time. Adequate anterior and lateral coverage of the femoral head in patients with computer-assisted PAO resulted in no need for early conversion to THA, in contrast to conventional PAO.

Conclusion

Computer-assisted PAO not only improved accuracy and safety but also achieved sufficient anterior and lateral displacement to prevent the progression of DDH.

Evaluation of Osseous Morphology of the Hip Using Zero Echo Time Magnetic Resonance Imaging

BACKGROUND

Femoroacetabular impingement syndrome (FAIS) is a common disorder of the hip resulting in groin pain and ultimately osteoarthritis. Radiologic assessment of FAI morphologies, which may present with overlapping radiologic features of hip dysplasia, often requires the use of computed tomography (CT) for evaluation of osseous abnormality, owing to the difficulty of direct visualization of cortical and subchondral bone with conventional magnetic resonance imaging (MRI). The use of a zero echo time (ZTE) MRI pulse sequence may obviate the need for CT by rendering bone directly from MRI.

PURPOSE/HYPOTHESIS

The purpose was to explore the application of ZTE MRI to the assessment of osseous FAI and dysplasia morphologies of the hip. It was hypothesized that angular measurements from ZTE images would show significant agreement with measurements obtained from CT images.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Thirty-eight hips from 23 patients were imaged with ZTE MRI and CT. Clinically relevant angular measurements of hip morphology were made in both modalities and compared to assess agreement. Measurements included coronal and sagittal center-edge angles, femoral neck-shaft angle, acetabular version (at 1-, 2-, and 3-o'clock positions), Tönnis angle, alpha angle, and modified-beta angle. Interrater agreement was assessed for a subset of 10 hips by 2 raters. Intermodal agreement was assessed on the complete cohort and a single rater.

RESULTS

Interrater agreement was demonstrated in both CT and ZTE, with intraclass correlation coefficient values ranging from 0.636 to 0.990 for ZTE and 0.747 to 0.983 for CT, indicating "good" to "excellent" agreement. Intermodal agreement was also shown to be significant, with intraclass correlation coefficients ranging from 0.618 to 0.904.

CONCLUSION

Significant agreement of angular measurements for hip morphology exists between ZTE MRI and CT imaging. ZTE MRI may be an effective method to quantitatively evaluate osseous hip morphology.