EOS(®) biplanar X-ray imaging: concept, developments, benefits, and limitations

Measurement of tibial slope using biplanar stereoradiography (EOS®)

OBJECTIVES

Posterior tibial slope (PTS) is an important anatomic parameter of the knee related to anteroposterior instability. Biplanar stereoradiography allows for simultaneous low-dose acquisition of anteroposterior and lateral views with 3D capability, enabling separate lateral and medial plateau analyses. We aimed to evaluate the possibility and compare the reproducibility of measuring medial and lateral PTS on EOS® images with two different patient positionings and compare it with CT of the knees as the gold standard.

METHODS

This is a retrospective study including volunteers who underwent lower limb stereoradiography and knee CT from 01/08/2016 to 07/31/2019. Sixty legs from 30 patients were studied. PTS were measured using stereoradiography and CT by two radiologists. Intraclass correlation was used to calculate intrarater and interrater reproducibilities. Pearson's correlation coefficients were used to calculate the correlation between stereoradiography and CT. We also compared the reproducibility of the stereoradiography of volunteers with 2 different positionings.

RESULTS

The mean stereoradiography PTS values for right and left knees were as follows: lateral, 12.2° (SD: 4.1) and 10.1° (SD: 3.5); medial,12.2° (SD: 4.4) and 11.6° (SD: 3.9). CT PTS mean values for right and left knee are as follows: lateral, 10.3° (SD:2.5) and 10.6° (SD: 2.8); medial: 8.7° (SD: 3.7) and 10.4° (SD: 3.5). Agreement between CT and EOS for angles between lateral and medial PTS was good (right, 0.874; left, 0.871). Regarding patient positioning on stereoradiography, interrater and intrarater reproducibilities were greater for patients with nonparallel feet (0.738-0.883 and 0.870-0.975).

CONCLUSIONS

Stereoradiography allows for appropriate delineation of tibial plateaus, especially in patients with nonparallel feet, for the purpose of measuring PTS. The main advantage is lower radiation doses compared to radiography and CT.

Evaluating pelvic tilt using the pelvic antero-posterior radiographs: A novel method

Pelvic tilt (PT) is an important parameter for orthopedic surgeries involving hip and spine, typically determined from sagittal pelvic radiographs. However, various challenges can compromise the feasibility of measurement from sagittal imaging, including obscured landmarks, anatomical variations, hardware interference, and limited medical resources. Addressing these challenges and with the aim of reducing radiation exposure to patients, our study developed a novel method to estimate PT from antero-posterior (AP) radiographs, using vertical distances from the pelvic outlet and obturator foramen. We correlated these measurements with PT, defined both anatomically (anterior pelvic plane, PTa) and mechanically (centers of femoral heads and sacral plate, PTm). The study explored creating linear, exponential, and multivariate regression models based on twelve 3D CT-derived pelvic models (six men, six women), simulating AP radiograph projections with controlled PTs. We then validated these models against 105 pairs of patient stereoradiographs. Statistical analysis revealed that combined exponential-linear models yielded the most accurate results, with Pearson correlation coefficients of 0.75 for PTa and 0.77 for PTm, and mean absolute errors of 3.7° ± 2.6° for PTa and 4.5° ± 3.4° for PTm, showing excellent measurement reliability (all ICCs > 0.9) without significant gender discrepancies. In conclusion, this study presents a validated, simple, and accessible method for estimating PT using AP radiograph parameters, supported by the Supporting Information S1: Excel Tool, showing great potential for clinical application in hip and spine procedures.

Advances in imaging for pre-surgical planning in hip resurfacing arthroplasty

BACKGROUND

Accurate preoperative templating is essential for the success of hip resurfacing arthroplasty (HRA). While digital radiograph is currently considered the gold standard, stereoradiograph and CT converted 3D methods have shown promising results. However, there is no consensus in the literature regarding the preferred modality for HRA templating, and angular measurements are often overlooked. Thus, this study aimed to: (1) compare the performances of different modality in implant sizing and angle measurements, (2) evaluate the measurement reproducibility, (3) assess the impact of severe osteoarthritis on femoral head sizing, and (4) based on the analysis above, explore the optimal imaging and planning strategy for HRA.

HYPOTHESIS

An optimal imaging modality exists for HRA planning regarding implant sizing and angular measurements.

MATERIALS AND METHODS

Preoperative imaging data from seventy-seven HRA surgeries were collected. Three raters performed templating using digital radiograph, stereoradiograph, and CT converted 3D models. Measurements for femoral head size, neck-shaft angle, and calcar-shaft angle were obtained. The femoral head sizing was compared to the intraoperative clinical decision. The reproducibility of measurements was assessed using the intraclass correlation coefficient (ICC). Correlations were examined between sizing disagreement and osteoarthritis grade (Tonnis Classification).

RESULTS

Digital radiograph, stereoradiograph, and 3D techniques predicted one size off target in 27/77 (35%), 49/70 (70%), and 75/77 (97%) of cases, respectively, corresponding to 1.8±1.6 (0 to 5.67), 0.9±0.7 (0 to 2.67), and 0.4±0.4 (0 to 1.67) sizes off target, indicating statistically significant differences among all three modalities, with p-values all below 0.01. There were no statistically significant differences among the different modalities for angular measurements. Measurements showed moderate to excellent reproducibility (ICC=0.628-0.955). High-grade osteoarthritis did not impact image sizing in any modality (r=0.08-0.22, all p>0.05).

DISCUSSION

CT converted 3D models were more accurate for implant sizing in HRA, but did not significantly outperform other modalities in angular measurements. Given the high costs and increased radiation exposure associated with CT, the study recommended using CT scans selectively, particularly for precise femoral head sizing, while alternative imaging methods can be effectively used for angular measurements.

LEVEL OF EVIDENCE

III; retrospective comparative diagnostic study.

How reliable are femoropelvic kinematics during deep squats? The influence of subject-specific skeletal modelling on measurement variability

BACKGROUND

Biplanar radiography displays promising results in the production of subject-specific (S.specific) biomechanical models. However, the focus has predominantly centred on methodological investigations in gait analysis. Exploring the influence of such models on the analysis of high range of motion tasks linked to hip pathologies is warranted. The aim of this study is to investigate the effect of S.Specific modelling techniques on the reliability of deep squats kinematics in comparison to generic modelling.

METHODS

8 able-bodied male participants attended 5 motion capture sessions conducted by 3 observers and performed 5 deep squats in each. Prior to each session a biplanar scan was acquired with the reflective-markers attached. Inverse kinematics of pelvis and thigh segments were calculated based on S.specific and Generic model definition. Agreement between the two models femoropelvic orientation in standing was assessed with Bland-Altman plots and paired t- tests. Inter-trial, inter-session, inter-observer variability and observer/trial difference and ratio were calculated for squat kinematic data derived from the two modelling approaches.

RESULTS

Compared to the Generic model, the S.Specific model produced a calibration trial that is significantly offset into more posterior pelvis tilt (-2.8±2.7), hip extension (-2.2±3.8), hip abduction (-1.2±3.6) and external rotation (-13.8±11.4). The S.specific model produced significantly different squat kinematics in the sagittal plane of the pelvis (entire squat cycle) and hip (between 40 % and 60 % of the squat cycle). Variability analysis indicated that the error magnitude between the two models was comparable (difference<2°). The S.specific model exhibited a lower variability in the observer/trial ratio in the sagittal pelvis and hip, the frontal hip, but showed a higher variability in the transverse hip.

SIGNIFICANCE

S.specific modelling appears to introduce a calibration offset that primarily translates into an effect in the sagittal plane kinematics. However, the clinical added value of S.specific modelling in terms of reducing experimental sources of kinematic variability was limited.

Improvement in axial rotation with bracing reduces the risk of curve progression in patients with adolescent idiopathic scoliosis

PURPOSE

New evidence highlights the significance of 3D in-brace correction for Adolescent Idiopathic Scoliosis (AIS) patients. This study explores how axial parameters relate to treatment failure in braced AIS patients.

METHODS

AIS patients (Sanders 1-5) undergoing Rigo-Chêneau bracing at a single institution were included. Axial vertebral rotation (AVR) was determined by utilizing pre-brace and in-brace 3D reconstructions from EOS® radiographs. The primary outcome was treatment failure: surgery or coronal curve progression > 5°. Minimum follow-up was two years.

RESULTS

75 patients (81% female) were included. Mean age at bracing initiation was 12.8 ± 1.3 years and patients had a pre-brace major curve of 31.0° ± 6.5°. 25 patients (76% female) experienced curve progression > 5°, and 18/25 required surgical intervention. The treatment failure group had larger in-brace AVR than the success group (5.8° ± 4.1° vs. 9.9° ± 7.6°, p = 0.003), but also larger initial coronal curve measures. In-brace AVR did not appear to be associated with treatment failure after adjusting for the pre-brace major curve (Hazard Ratio (HR):0.99, 95% Confidence Interval (CI):0.94-1.05, p = 0.833). Adjusting for pre-brace major curve, patients with AVR improvement with bracing had an 85% risk reduction in treatment failure versus those without (HR:0.15, 95% CI:0.02-1.13, p = 0.066). At the final follow-up, 42/50 (84%) patients without progression had Sanders ≥ 7.

CONCLUSIONS

While in-brace rotation was not an independent predictor of curve progression (due to its correlation with curve magnitude), improved AVR with bracing was a significant predictor of curve progression. This study is the first step toward investigating the interplay between 3D parameters, skeletal maturity, compliance, and brace efficacy, allowing a future prospective multicenter study.

LEVEL OF EVIDENCE

Retrospective study; Level III.

Deep learning-based identification of spine growth potential on EOS radiographs

OBJECTIVES

To develop an automatic computer-based method that can help clinicians in assessing spine growth potential based on EOS radiographs.

METHODS

We developed a deep learning-based (DL) algorithm that can mimic the human judgment process to automatically determine spine growth potential and the Risser sign based on full-length spine EOS radiographs. A total of 3383 EOS cases were collected and used for the training and test of the algorithm. Subsequently, the completed DL algorithm underwent clinical validation on an additional 440 cases and was compared to the evaluations of four clinicians.

RESULTS

Regarding the Risser sign, the weighted kappa value of our DL algorithm was 0.933, while that of the four clinicians ranged from 0.909 to 0.930. In the assessment of spine growth potential, the kappa value of our DL algorithm was 0.944, while the kappa values of the four clinicians were 0.916, 0.934, 0.911, and 0.920, respectively. Furthermore, our DL algorithm obtained a slightly higher accuracy (0.973) and Youden index (0.952) compared to the best values achieved by the four clinicians. In addition, the speed of our DL algorithm was 15.2 ± 0.3 s/40 cases, much faster than the inference speeds of the clinicians, ranging from 177.2 ± 28.0 s/40 cases to 241.2 ± 64.1 s/40 cases.

CONCLUSIONS

Our algorithm demonstrated comparable or even better performance compared to clinicians in assessing spine growth potential. This stable, efficient, and convenient algorithm seems to be a promising approach to assist doctors in clinical practice and deserves further study.

CLINICAL RELEVANCE STATEMENT

This method has the ability to quickly ascertain the spine growth potential based on EOS radiographs, and it holds promise to provide assistance to busy doctors in certain clinical scenarios.

KEY POINTS

• In the clinic, there is no available computer-based method that can automatically assess spine growth potential. • We developed a deep learning-based method that could automatically ascertain spine growth potential. • Compared with the results of the clinicians, our algorithm got comparable results.

Imaging in osteogenesis imperfecta: Where we are and where we are going

Osteogenesis imperfecta (OI) is a rare phenotypically and genetically heterogeneous group of inherited skeletal dysplasias. The hallmark features of OI include bone fragility and susceptibility to fractures, bone deformity, and diminished growth, along with a plethora of associated secondary features (both skeletal and extraskeletal). The diagnosis of OI is currently made on clinical grounds and may be confirmed by genetic testing. However, imaging remains pivotal in the evaluation of this disease. The aim of this article is to review the current role played by the various radiologic techniques in the diagnosis and monitoring of OI in the postnatal setting as well as to discuss recent advances and future perspectives in OI imaging. Conventional Radiography and Dual-energy X-ray Absorptiometry (DXA) are currently the two most used imaging modalities in OI. The cardinal radiographic features of OI include generalized osteopenia/osteoporosis, bone deformities, and fractures. DXA is currently the most available technique to assess Bone Mineral Density (BMD), specifically areal BMD (aBMD). However, DXA has important limitations and cannot fully characterize bone fragility in OI based on aBMD. Novel DXA-derived parameters, such as Trabecular Bone Score (TBS), may provide further insight into skeletal changes induced by OI, but evidence is still limited. Techniques like Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) can be useful as problem-solvers or in specific settings, including the evaluation of cranio-cervical abnormalities. Recent evidence supports the use of High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT) as a promising tool to improve the characterization of bone fragility in OI. However, HR-pQCT remains a primarily research technique at present. Quantitative Computed Tomography (QCT) is an alternative to DXA for the determination of BMD at central sites, with distinct advantages but considerably higher radiation exposure. Quantitative Ultrasound (QUS) is a portable, inexpensive, and radiation-free modality that may complement DXA evaluation, providing information on bone quality. However, evidence of usefulness of QUS in OI is poor. Radiofrequency Echographic Multi Spectrometry (REMS) is an emerging non-ionizing imaging method that holds promise for the diagnosis of low BMD and for the prediction of fracture risk, but so far only one published study has investigated its role in OI. To conclude, several different radiologic techniques have proven to be effective in the diagnosis and monitoring of OI, each with their own specificities and peculiarities. Clinicians should be aware of the strategic role of the various modalities in the different phases of the patient care process. In this scenario, the development of international guidelines including recommendations on the role of imaging in the diagnosis and monitoring of OI, accompanied by continuous active research in the field, could significantly improve the standardization of patient care.

Evaluating Pelvic Tilt Using the Pelvic Antero-Posterior Projection Images: A Systematic Review

BACKGROUND

Pelvic tilt (PT) is a routinely evaluated parameter in hip and spine surgeries, and is usually measured on a sagittal pelvic radiograph. This may not always be feasible due to limitations such as landmark visibility, pelvic anomaly, and hardware presence. Tremendous efforts have been dedicated to using pelvic antero-posterior (AP) radiographs for assessing sagittal PT. Thus, this systematic review aimed to collect these methods and evaluate their performances.

METHODS

Two independent reviewers searched the PubMed, Ovid, Cochrane, and Web of Science databases in June 2023 with backward reference trailing (Google Scholar archive). There were 30 studies recruited. Risk of bias was assessed using the prediction model risk of bias assessment tool. The relevant data were tabulated in a standardized form for evaluating either the absolute PT or relative PT. Disagreement was resolved by discussing with the senior author.

RESULTS

There were 19 parameters from pelvic AP projection images involved, with 4 studies which used artificial intelligence, eyeball, or statistical shape method not involving a specific parameter. In comparing the PT values from pelvic sagittal images with those extrapolated from antero-posterior projection images, the highest correlation coefficient was found to be 0.91. The mean absolute difference (error) was 2.6°, with a maximum error reaching 10.9°. Most studies supported the feasibility of using AP parameters to calculate changes in PT.

CONCLUSIONS

No individual AP parameter was found to precisely estimate absolute PT. However, relative PT can be derived by evaluating serial AP radiographs of a patient in varying postures, employing any AP parameters.

Relationship between spinal structural damage and sagittal balance in axial spondyloarthritis: Is the thoracic spine the starting point?

OBJECTIVES

To assess the relationship between spinal structural damage, sagittal balance parameters and spine curvatures in patients with axial spondyloarthritis (axSpA).

MATERIAL AND METHODS

In this cross-sectional study, the pelvic and sagittal balance parameters were obtained through EOS® (Biospace, Paris, France). Patients were divided into three groups according to the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) tertiles (G1 ≤6, n = 36; G2: 6.1-31, n = 36; G3 >31, n = 35) and pelvic and sagittal parameters were compared across them. Multivariable regression analysis was performed to analyze the impact of spinal structural damage and of other factors on sagittal vertical axis (SVA), an important sagittal balance parameter.

RESULTS

A total of 107 patients was included. G2 and 3 exhibited higher mean values of thoracic kyphosis T1-T12 when compared to G1 (10.5°(12.3) vs. 22.3°(17.3) vs. 35.2°(14.6), p < 0.001), and G3 demonstrated lumbar L1-S1 straightening compared to the other groups (55.7°(9) and 50.7°(19.8), G1 and G2, respectively, vs. 35.7°(13.2), p < 0.001). Mean SVA values showed an increasing gradient from G1 to G3 (21.6(25.1) vs. 41(44.3) vs. 84.3(47.2)mm, p < 0.001). In the multivariable regression, a one-unit increase in total mSASSS was associated with an average 0.8 mm higher SVA.

CONCLUSIONS

Our data showed that more spinal structural damage is associated with a higher SVA, reflecting poorer sagittal balance. Patients with increasing spinal damage have an important increase in thoracic kyphosis suggesting that postural modifications in patients with axSpA might have their origin in the thoracic spine.

Where should Scoliometer and EOS Imaging be Applied when Evaluating Spinal Rotation in Adolescent Idiopathic Scoliosis -A Preliminary Study with Reference to CT Images

STUDY DESIGN

Retrospective study.

OBJECTIVE

Our purpose was to evaluate spinal rotation measurement by scoliometer or EOS Imagings with reference to that by CT images, and to clarify their applicability in clinical practice.

METHODS

Patients with adolescent idiopathic scoliosis (AIS) who were indicated for surgery were enrolled and the informed consents were obtained. The angle of trunk rotation (ATR) was measured by the scoliometer. Apical vertebral rotation (AVR) was measured with EOS Imaging and CT images. Paired T tests were used to compare the measurements between ATR or AVR-EOS and AVR-CT. Pearson correlation analysis was performed to explore the relationship between ATR or AVR-EOS and AVR-CT. Then subgroup analysis was performed.

RESULTS

Forty-seven consecutive AIS patients with 62 curves were identified. In the whole group, the ATR, as well as AVR-EOS, was significantly smaller than the AVR-CT. Both ATR and AVR-EOS correlated with AVR-CT, although AVR-EOS correlated better. In thoracic group, there was no significant difference between ATR and AVR-CT (P = .236). A significant correlation was found between ATR and AVR-CT(r = .574, P < .001). In TL/L group, no significant difference was noted between AVR-EOS and AVR-CT (P = .414), and a significant correlation was found between AVR-EOS and AVR-CT(r = .824, P < .001).

CONCLUSION

ATR by scoliometer is numerically similar to AVR by CT and may evaluate the spinal rotation more appropriately in thoracic spine. AVR by EOS is numerically similar to AVR by CT and may be more applicable in TL/L spine. Appropriate methods could be selected according to the location of the curve.

5-Year Radiographic and Functional Outcomes of Nonoperative Treatment of Completely Displaced Midshaft Clavicular Fractures in Teenagers

BACKGROUND

Optimal treatment of completely displaced midshaft clavicular fractures in adolescents remains controversial, with some favoring surgical management and others favoring a nonoperative approach. Few studies have comprehensively assessed longer-term nonoperative outcomes.

PURPOSE

To prospectively assess patient-reported outcomes (PROs) and radiographic remodeling ≥5 years after injury in teenagers undergoing nonoperative treatment of completely displaced clavicular fractures.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Adolescent patients previously enrolled in a prospective study from a single institution with nonoperatively treated, completely displaced midshaft clavicular fractures ≥5 years from injury were eligible for the study. Patients were clinically evaluated for scapular dyskinesia and strength deficits. Bilateral clavicular imaging assessed residual shortening, displacement, and angulation. PROs included the American Shoulder and Elbow Surgeons (ASES), the shortened version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH), Marx Shoulder Activity Scale, cosmesis, and return to sports data.

RESULTS

A total of 24 patients were available for the follow-up, of whom 17 (71%) consented to additional imaging. The mean cohort age at the time of injury was 14.5 ± 1.1 years, with 88% being male. At a mean follow-up of 6.1 years, all fractures had healed, with no patient requiring secondary interventions. Significant remodeling was observed across all measurements, with improvements of 70% in shortening (22.8 to 6.8 mm; P < .001), 73% in superior displacement (13.4 to 3.6 mm; P < .001), and 83% in angulation (10.4° to 1.8°; P < .001). Thirteen patients (72%) had a >2-cm initial shortening, and all remodeled to <2 cm. PROs were almost universally excellent, with mean ASES, QuickDASH, and Marx activity scores of 99 ± 3, 1 ± 3, and 20 ± 1, respectively, with 79% of patients reporting perfect scores in all 3 domains. Most patients (58%) were completely satisfied with their shoulder appearance, 38% were more satisfied than not, 1 patient (4%) was neither satisfied nor dissatisfied, and no patients were dissatisfied. All patients except 1 who were interested in sports returned to sporting activities. PROs were not associated with bony remodeling (P > .05).

CONCLUSION

Teenaged patients with completely displaced clavicular fractures treated nonoperatively can expect excellent radiographic and clinical outcomes 5 years after injury.

Towards a better understanding of knee angular deformities: discrepancies between clinical examination and 2D/3D assessments

INTRODUCTION

Discrepancy between the clinical examination and the 2D/3D radiographs is a common concern in patients with angular or rotational deformities of the lower limbs, as it may alter clinical judgment and subsequent treatment. The aim was to identify such discrepancies and assess determinants that may contribute to their existence.

MATERIALS AND METHODS

A retrospective chart review was conducted on 329 consecutive patients (658 lower limbs) who underwent physical examination and long-leg biplanar radiographs in our institution between 2013 and 2018 for limb length discrepancy or angular deformity of the knees (varus/valgus). Eleven parameters were measured on 2D and 3D images. 3D measurements were based on standing biplanar X-rays and their 3D reconstructions and were considered the gold standard. Contingency tables and multiple linear regression were used to assess discrepancies between the three modalities and their determinants respectively.

RESULTS

Significant mismatches were found between physical examination and 2D images (1% in varus and 1% in valgus), between physical examination and 3D assessment (1% in varus and 4.6% in valgus) as well as between 2 and 3D assessments (1.9% in varus and 7.6% in valgus). The significant determinants of the mismatch between 2 and 3D modalities were frontal pelvic obliquity, neck shaft angle, knee flexion, femoral torsion, and tibial mechanical angle.

CONCLUSION

In the presence of positional and/or morphological deformities, physical examination and 2D assessment of knee alignment could be biased due to axes projection errors. A better understanding of 3D alignment of the knee as part of the entire lower limb from pelvis to toes, may lead to a better diagnosis and subsequently a better treatment of knee angular deformities.

Associations between femoral 3D curvature and sagittal imbalance of spine

Background

The sagittal imbalance (SI) of spine triggers compensatory mechanisms (CMs) of lower extremity (LE) to restore trunk balance. These CMs can cause long-period stress on the femur and may possibly alter the femoral morphology. This cross-sectional observational study aimed to answer the following questions: (a) Do SI subjects exhibit greater femoral bowing compared to subjects with sagittal balance? (b) Are there associations between femoral bowing and CMs of LE in SI subjects?

Methods

Subjects who underwent biplanar full body radiographs with the EOS imaging system between January 2016 and September 2021 were recruited. Sagittal parameters included T1-pelvic angle (TPA), pelvic incidence (PI), pelvic tilt (PT), sacral slope, lumbar lordosis (LL), PI-LL, and PT/PI ratio. LE parameters were femoral obliquity angle (FOA), knee flexion angle (KA), and ankle dorsiflexion angle. Femoral bowing was quantified as 3D radius of femoral curvature (RFC). Associations between 3D RFC and the radiographic parameters were analyzed.

Results

A total of 105 subjects were included, classified into balance group (TPA < 14°, n = 40), SI group (TPA ≥ 14° and KA <5°, n = 30), and SI with knee flexion group (TPA ≥ 14° and KA ≥ 5°, n = 35). 3D RFC was significantly lower in SI with knee flexion group compared to the other two groups (both p < 0.001). Stepwise linear regression showed that age, SI and knee flexion, femoral length (FL), FOA, and KA were independent predictors for 3D RFC.

Conclusion

Greater femoral bowing is observed in subjects with SI and knee flexion compared to the balanced population. CM parameters, including KA and FOA, are associated with 3D RFC. Further longitudinal study is needed to investigate the cause-and-effect relationship between SI, CMs of LE, and femoral bowing.

Narrative Review of Clinical Impact of Head-Hip Offset Following Adult Spinal Deformity Surgery

In adult spinal deformity (ASD) surgery, mechanical failure (MF) has been a significant concern for spine surgeons as well as patients. Despite earnest endeavors to prevent MF, the absence of a definitive consensus persists, owing to the intricate interplay of multifarious factors associated with this complication. Previous approaches centered around global spinal alignment have yielded limited success in entirely forestalling MF. These methodologies, albeit valuable, exhibited limitations by neglecting to encompass global balance and compensatory mechanisms within their purview. In response to this concern, an in-depth comprehension of global balance and compensatory mechanisms emerges as imperative. In this discourse, the center of gravity and the gravity line are gaining attention in recent investigations pertaining to global balance. This narrative review aims to provide an overview of the global balance and a comprehensive understanding of related concepts and knowledge. Moreover, it delves into the clinical ramifications of the contemporary optimal correction paradigm to furnish an encompassing understanding of global balance and the current optimal correction strategies within the context of ASD surgery. By doing so, it endeavors to furnish spine surgeons with a guiding compass, enriching their decision-making process as they navigate the intricate terrain of ASD surgical interventions.

Inadequate Annotation and Its Impact on Pelvic Tilt Measurement in Clinical Practice

BACKGROUND

Accurate pre-surgical templating of the pelvic tilt (PT) angle is essential for hip and spine surgeries, yet the reliability of PT annotations is often compromised by human error, inherent subjectivity, and variations in radiographic quality. This study aims to identify challenges leading to inadequate annotations at a landmark dimension and evaluating their impact on PT.

METHODS

We retrospectively collected 115 consecutive sagittal radiographs for the measurement of PT based on two definitions: the anterior pelvic plane and a line connecting the femoral head's centre to the sacral plate's midpoint. Five annotators engaged in the measurement, followed by a secondary review to assess the adequacy of the annotations across all the annotators.

RESULTS

The outcomes indicated that over 60% images had at least one landmark considered inadequate by the majority of the reviewers, with poor image quality, outliers, and unrecognized anomalies being the primary causes. Such inadequacies led to discrepancies in the PT measurements, ranging from -2° to 2°.

CONCLUSION

This study highlights that landmarks annotated from clear anatomical references were more reliable than those estimated. It also underscores the prevalence of suboptimal annotations in PT measurements, which extends beyond the scope of traditional statistical analysis and could result in significant deviations in individual cases, potentially impacting clinical outcomes.

Correlation of transverse rotation of the spine using surface topography and 3D reconstructive radiography in children with idiopathic scoliosis

PURPOSE

The relationship between axial surface rotation (ASR) measured by surface topography (ST) and axial vertebral rotation (AVR) measured by radiography in the transverse plane is not well defined. This study aimed to: (1) quantify ASR and AVR patterns and their magnitudes from T1 to L5; (2) determine the correlation or agreement between the ASR and AVR; and (3) investigate the relationship between axial rotation differences (ASR-AVR) and major Cobb angle.

METHODS

This is a retrospective study evaluating patients (age 8-18) with IS or spinal asymmetry with both radiographic and ST measurements. Demographics, descriptive analysis, and correlations and agreements between ASR and AVR were evaluated. A piecewise linear regression model was further created to relate rotational differences to Cobb angle.

RESULTS

Fifty-two subjects met inclusion criteria. Mean age was 14.1 ± 1.7 and 39 (75%) were female. Looking at patterns, AVR had maximal rotation at T8, while ASR had maximal rotation at T11 (r = 0.35, P = .006). Cobb angle was 24.1° ± 13.3° with AVR of - 1° ± 4.6° and scoliotic angle was 20.9° ± 11.5° with ASR of - 2.3° ± 6.6°. (ASR-AVR) vs Cobb angle was found to be very weakly correlated with a curve of less than 38.8° (r = 0.15, P = .001).

CONCLUSION

Our preliminary findings support that ASR measured by ST has a weak correlation with estimation of AVR by 3D radiographic reconstruction. This correlation may further help us to understand the application of transverse rotation in some clinical scenarios such as specific casting manipulation, padding mechanism in brace, and surgical correction of rib deformity.

How does long thoracolumbar realignment surgery of adult spinal kyphotic deformity affect lower extremity compensation? Using full body radiograph

PURPOSE

By using full body radiograph, the aim of the current study was to elucidate the expected degree of lower extremity compensatory change after long thoracolumbar realignment surgery with adult spinal deformity patient who had normal or only mild osteoarthritis on lower extremities.

METHODS

Two novel parameters were used for assessment of regional compensation of the lower extremity. The Pearson correlation test was used to assess the correlation of postoperative changes of lower extremity compensation with the other spinopelvic parameters.

RESULTS

Overall, 113 spinal deformity patients (mean age was 54.5 years) were recruited and the average number of fused vertebrae was 13.3 ± 3.5. Except pelvic tilt (PT), postoperative sacrum-femur angle (SF) changes showed only moderate correlation with all angular spinopelvic parameters (r = 0.323-0.374; p < .001 to p = .001). Also C7 sagittal vertical axis showed no significant correlation with SF (p = .584-.621). However, postoperative changes of sagittal femur-tibia angle (SFT) reported strong correlation with all parameters evaluated (r = 0.455-0.586; p < .001 to p = .046).

CONCLUSION

For adult spinal deformity patients who had normal or only mild osteoarthritis on the lower extremities underwent long thoracolumbar realignment surgery, the surgeon could expect improvement of compensatory change of the knee with correction of spinopelvic parameters. However, the degree of hip compensation improvement was relatively difficult to predict than that of the knee, except PT.

3D Back Contour Metrics in Predicting Idiopathic Scoliosis Progression: Retrospective Cohort Analysis, Case Series Report and Proof of Concept

Adolescent Idiopathic Scoliosis is a 3D spinal deformity commonly characterized by serial radiographs. Patients with AIS may have increased average radiation exposure compared to unaffected patients and thus may be implicated with a modest increase in cancer risk. To minimize lifetime radiation exposure, alternative imaging modalities such as surface topography are being explored. Surface topography (ST) uses a camera to map anatomic landmarks of the spine and contours of the back to create software-generated spine models. ST has previously shown good correlation to radiographic measures. In this study, we sought to use ST in the creation of a risk stratification model. A total of 38 patients met the inclusion criteria for curve progression prediction. Scoliotic curves were classified as progressing, stabilized, or improving, and a predictive model was created using the proportional odds logistic modeling. The results showed that surface topography was able to moderately appraise scoliosis curvatures when compared to radiographs. The predictive model, using demographic and surface topography measurements, was able to account for 86.9% of the variability in the future Cobb angle. Additionally, attempts at classification of curve progression, stabilization, or improvement were accurately predicted 27/38 times, 71%. These results provide a basis for the creation of a clinical tool in the tracking and prediction of scoliosis progression in order to reduce the number of X-rays required.

The tibial tubercle-trochlear groove distance: a comparison study between EOS and MRI in the paediatric population

OBJECTIVE

This study aims to compare the relative reliability and accuracy of TT-TG measurements in EOS with that of MRI in a paediatric population.

METHODS

Patients were included if they underwent both an MRI and EOS scans and were under the age of 16. Two authors recorded the TT-TG distances on each modality at two separate time points. In the EOS images, the distance between the two points was measured in the horizontal 2D plane. In the MRI images, it was done in the plane referenced by posterior femoral condylar axis. The intra- and inter-rater reliability was assessed in each modality and between modalities.

RESULTS

Twenty-seven patients (30 knees), 14 males, and 13 females with an average age of 13 years (range: 7-16 years) were included in the study. The mean TT-TG distance on EOS scan and MRI scan was 14 mm. On inter- and intra-observer analysis, both imaging modalities had excellent reliability (0.97 ICC for EOS and 0.98 ICC for MRI inter-observer) and repeatability (0.98-0.99 ICC for EOS and 0.99 ICC for MRI for intra-observer). However, on comparing the two imaging modalities (EOS vs MRI), the ICC was fair (0.56 ICC for rater 1 and 0.65 ICC for rater 2).

CONCLUSION

While the EOS TT-TG measurements were precise and reproducible, they were only moderately comparable to MRI TT-TG measurements. Consequently, EOS TT-TG measurements should not be used for decision-making without the development of EOS-specific TT-TG values that indicate the need for distal realignment surgery.

LEVEL OF EVIDENCE

Level II.

Weight-bearing cone-beam CT with extensive coverage for volumetric imaging in adolescent idiopathic scoliosis: system implementation and initial validation

The study aimed to introduce a novel imaging method that generates large-coverage, weight-bearing, and 3D images of the whole spine. The proposed system comprises an X-ray tube, a flat panel detector, and a standing platform. The standing platform rotates the imaged subject, allowing for the acquisition of serial fluoroscopic images from different angles which can be used to create 3D images. To increase the longitudinal coverage, we apply a segmental scanning pattern in which the imaged region is scanned in segments and stitched. To address the issue of data inaccuracy between the segments, redundant areas are set at margins of the segmental images, and registration and stitching algorithms are applied. We conducted validation experiments to evaluate radiation dose and image quality. The dose was evaluated using the volume CT dose index (CTDIvol). For image quality evaluation, we measured the low-contrast and spatial resolution. Additionally, we conducted a clinical study consisting of 30 volunteers with adolescent idiopathic scoliosis who were imaged by our method, and the images were subjectively assessed based on image noise, artifacts, anatomical coverage, diagnostic confidence, and overall quality. The CTDIvol was 1.23 mGy, and the low-contrast resolution was 0.6% at 4 mm and the spatial resolution was 8 lp/cm. The clinical images were generally of good quality, with high scores for all factors evaluated. Our method successfully generates large-coverage, weight-bearing, and 3D images of the whole spine with high image quality and low radiation dose. It shows potential for wider clinical applications for various musculoskeletal conditions.

Examination of 2D frontal and sagittal markerless motion capture: Implications for markerless applications

This study examined if occluded joint locations, obtained from 2D markerless motion capture (single camera view), produced 2D joint angles with reduced agreement compared to visible joints, and if 2D frontal plane joint angles were usable for practical applications. Fifteen healthy participants performed over-ground walking whilst recorded by fifteen marker-based cameras and two machine vision cameras (frontal and sagittal plane). Repeated measures Bland-Altman analysis illustrated that markerless standard deviation of bias and limits of agreement for the occluded-side hip and knee joint angles in the sagittal plane were double that of the camera-side (visible) hip and knee. Camera-side sagittal plane knee and hip angles were near or within marker-based error values previously observed. While frontal plane limits of agreement accounted for 35-46% of total range of motion at the hip and knee, Bland-Altman bias and limits of agreement (-4.6-1.6 ± 3.7-4.2˚) were actually similar to previously reported marker-based error values. This was not true for the ankle, where the limits of agreement (± 12˚) were still too high for practical applications. Our results add to previous literature, highlighting shortcomings of current pose estimation algorithms and labelled datasets. As such, this paper finishes by reviewing methods for creating anatomically accurate markerless training data using marker-based motion capture data.

Calibration of magnification in two-dimensional low-dose full-body imaging for preoperative planning of total hip arthroplasty

INTRODUCTION

Preoperative planning of total hip arthroplasty (THA) using two-dimensional low-dose (2DLD) full-body imaging has gained popularity in recent years. The low-dose imaging system is said to produce a calibrated image with constant 1:1 magnification. However, the planning software used in conjunction with those images may introduce variations in the degree of magnification in 2DLD imaging, and this has not yet been investigated. The purpose of the present study was to quantify any variation in 2DLD image to assess the need for image calibration when using conventional planning software.

METHODS

Postoperative 2DLD images from 137 patients were retrospectively evaluated. Only patients who underwent THA for primary osteoarthritis were included in the study cohort. The femoral head diameter was measured by two independent observers using both Orthoview™ and TraumaCad™ planning software programs. Actual sizes of the femoral head implants were extracted from surgical reports to calculate image magnification. Magnification measurement reliability was calculated with the intra-class correlation coefficient (ICC) index.

RESULTS

Image magnification varied among cases (mean 133%, range 129-135%). There was no statistical difference in mean image magnification among the various implant sizes (p = 0.8). Mean observer and inter-observer reliability was rated excellent.

CONCLUSION

THA planning with 2DLD imaging is subject to variation in magnification as analyzed with conventional planning software in this series. This finding is of paramount importance for surgeons using 2DLD imaging in preparation for THA since errors in magnification could affect the accuracy of preoperative planning and ultimately the clinical outcome.

Coronal and sagittal alignment of ankle joint is significantly affected by high tibial osteotomy

PURPOSE

Changes in coronal and sagittal alignment of the knee joint after HTO have been reported in several previous studies. However, only few of them investigated the changes only on coronal alignment of the ankle joint. The purpose of this study was to investigate changes in both coronal and sagittal alignment of the ankle joint after HTO.

METHODS

46 patients (49 cases) who underwent HTO were retrospectively analyzed. Preoperative and postoperative lower extremity scanogram and EOS imaging system were investigated. The hip-knee-ankle (HKA) angle, medial proximal tibial angle (MPTA), and knee tibia plafond angle (KTPA) were measured by scanogram to evaluate coronal alignment of the knee. Tibial anterior surface angle (TAS), talar tilt (TT), tibial plafond inclination (TPI), and ankle joint axis point on the weight-bearing-line (AAWBL) ratio were measured by scanogram to investigate coronal alignment of the ankle. Knee lateral ankle surface angle (KLAS) and tibial lateral surface angle (TLS) were measured by EOS to evaluate sagittal alignment of the ankle.

RESULTS

Varus alignment of the knee was corrected by significant change of the HKA angle (5.8 ± 3.1° vs. - 2.1 ± 2.8°, p < 0.001), MPTA (85.7 ± 2.9° vs. 91.7 ± 3.3°, p < 0.001), and KTPA (5.0 ± 3.5° vs. - 2.1 ± 4.2°, p < 0.001) after HTO. Regarding the ankle coronal alignment, there was significant change in TPI (3.9 ± 3.4° vs. - 0.9 ± 3.8°, p < 0.001) and AAWBL ratio (45.5 ± 14.7% vs. 61.6 ± 13.3%, p < 0.001). In sagittal alignment of the ankle, KLAS (4.5 ± 3.1° vs. 7.7 ± 3.7°, p < 0.001) significantly increased. Among the variables, the amount of correction in AAWBL ratio (R = 0.608, p < 0.01) showed strongest relationship with tibial correction angle.

CONCLUSION

Based on the present study, coronal and sagittal alignment of ankle joint was significantly affected by HTO. After HTO, AAWBL ratio increased due to lateralization of the ankle joint axis, and KLAS increased due to increased posterior tibial slope.

LEVEL OF EVIDENCE

III.

Analysis of lower extremity alignment (LEA) in children with recurrent patellar dislocation by EOS system

Objectives

Recurrent patellar dislocation (RPD) greatly affects active young individuals, necessitating the identification of risk factors for a better understanding of its cause. Previous research has connected RPD to lower limb alignment (LEA) abnormalities, such as increased femoral anteversion, tibial external rotation, knee valgus, and flexion. This study aims to use EOS technology to detect RPD-related LEA anomalies, enabling three-dimensional assessment under load conditions.

Methods

A total of 100 limbs (50 in the RPD group, 50 in the control group) were retrospectively analyzed. In the RPD group, we included limbs with recurrent patellar dislocation, characterized by dislocations occurs at least two times, while healthy limbs served as the control group. We used EOS technology, including 2D and 3D imaging, to measure and compare the following parameters between the two groups in a standing position: Femoral neck shaft angle (NSA), Mechanical femoral tibial angle (MFTA), Mechanical lateral distal femoral angle (mLDFA), Medial proximal tibial angle (MPTA), Anatomical femoral anteversion (AFA), External tibial torsion (ETT), and Femorotibial rotation (FTR).

Results

The significant differences between the two groups were shown in NSA 3/2D, MFTA 3/2D, mLDFA 3/2D, MPTA 3D, AFA, FTR. No significant difference was shown in MPTA 2D, ETT between the RPD group and the control group. Further binary logistic regression analysis. Further binary logistic regression analysis was conducted on the risk factors affecting RPD mentioned above. and found four risk factors for binary logistic regression analysis: mLDFA (3D), AFA, NSA(3D), and FTR.

Conclusions

EOS imaging identified abnormal LEA parameters, including NSA, MFTA, mLDFA, MPTA, AFA, and FTR, as risk factors for RPD. Children with these risk factors should receive moderate knee joint protection.

Advances and Evolving Challenges in Spinal Deformity Surgery

BACKGROUND

Surgical intervention is a critical tool to address adult spinal deformity (ASD). Given the evolution of spinal surgical techniques, we sought to characterize developments in ASD correction and barriers impacting clinical outcomes.

METHODS

We conducted a literature review utilizing PubMed, Embase, Web of Science, and Google Scholar to examine advances in ASD surgical correction and ongoing challenges from patient and clinician perspectives. ASD procedures were examined across pre-, intra-, and post-operative phases.

RESULTS

Several factors influence the effectiveness of ASD correction. Standardized radiographic parameters and three-dimensional modeling have been used to guide operative planning. Complex minimally invasive procedures, targeted corrections, and staged procedures can tailor surgical approaches while minimizing operative time. Further, improvements in osteotomy technique, intraoperative navigation, and enhanced hardware have increased patient safety. However, challenges remain. Variability in patient selection and deformity undercorrection have resulted in heterogenous clinical responses. Surgical complications, including blood loss, infection, hardware failure, proximal junction kyphosis/failure, and pseudarthroses, pose barriers. Although minimally invasive approaches are being utilized more often, clinical validation is needed.

CONCLUSIONS

The growing prevalence of ASD requires surgical solutions that can lead to sustained symptom resolution. Leveraging computational and imaging advances will be necessary as we seek to provide comprehensive treatment plans for patients.

Enhanced Recovery After Surgery Protocols and Spinal Deformity

The authors outline a review of preoperative, intraoperative, and postoperative considerations surrounding adult spinal deformity. Preoperative management topics include imaging, hemoglobin A1c levels before spine surgery, osteoporotic management, and prehabilitation. Topics surrounding intraoperative management include the use of antibiotics, liposomal bupivacaine, and Foley catheters. The authors also discuss postoperative questions surrounding analgesia, nausea and vomiting, thromboembolic prophylaxis, and early mobilization. Throughout their discussion, the authors incorporate enhanced recovery after surgery protocols to hopefully lead to future discussions regarding optimizing complex spinal patients.

Deep Learning Model to Classify and Monitor Idiopathic Scoliosis in Adolescents Using a Single Smartphone Photograph

Importance

Adolescent idiopathic scoliosis (AIS) is the most common pediatric spinal disorder. Routine physical examinations by trained personnel are critical to diagnose severity and monitor curve progression in AIS. In the presence of concerning malformation, radiographs are necessary for diagnosis or follow-up, guiding further management, such as bracing correction for moderate malformation and spine surgery for severe malformation. If left unattended, progressive deterioration occurs in two-thirds of patients, leading to significant health concerns for growing children.

Objective

To assess the ability of an open platform application (app) using a validated deep learning model to classify AIS severity and curve type, as well as identify progression.

Design, Setting, and Participants

This diagnostic study was performed with data from radiographs and smartphone photographs of the backs of adolescent patients at spine clinics. The ScolioNets deep learning model was developed and validated in a prospective training cohort, then incorporated and tested in the AlignProCARE open platform app in 2022. Ground truths (GTs) included severity, curve type, and progression as manually annotated by 2 experienced spine specialists based on the radiographic examinations of the participants' spines. The GTs and app results were blindly compared with another 2 spine surgeons' assessments of unclothed back appearance. Data were analyzed from October 2022 to February 2023.

Exposure

Acquisitions of unclothed back photographs using a mobile app.

Main Outcomes and Measures

Outcomes of interest were classification of AIS severity and progression. Quantitative statistical analyses were performed to assess the performance of the deep learning model in classifying the deformity as well as in distinguishing progression during 6-month follow-up.

Results

The training data set consisted of 1780 patients (1295 [72.8%] female; mean [SD] age, 14.3 [3.3] years), and the prospective testing data sets consisted of 378 patients (279 [73.8%] female; mean [SD] age, 14.3 [3.8] years) and 376 follow-ups (294 [78.2%] female; mean [SD] age, 15.6 [2.9] years). The model recommended follow-up with an area under receiver operating characteristic curve (AUC) of 0.839 (95% CI, 0.789-0.882) and considering surgery with an AUC of 0.902 (95% CI, 0.859-0.936), while showing good ability to distinguish among thoracic (AUC, 0.777 [95% CI, 0.745-0.808]), thoracolumbar or lumbar (AUC, 0.760 [95% CI, 0.727-0.791]), or mixed (AUC, 0.860 [95% CI, 0.834-0.887]) curve types. For follow-ups, the model distinguished participants with or without curve progression with an AUC of 0.757 (95% CI, 0.630-0.858). Compared with both surgeons, the model could recognize severities and curve types with a higher sensitivity (eg, sensitivity for recommending follow-up: model, 84.88% [95% CI, 75.54%-91.70%]; senior surgeon, 44.19%; junior surgeon, 62.79%) and negative predictive values (NPVs; eg, NPV for recommending follow-up: model, 89.22% [95% CI, 84.25%-93.70%]; senior surgeon, 71.76%; junior surgeon, 79.35%). For distinguishing curve progression, the sensitivity and NPV were comparable with the senior surgeons (sensitivity, 63.33% [95% CI, 43.86%-80.87%] vs 77.42%; NPV, 68.57% [95% CI, 56.78%-78.37%] vs 72.00%). The junior surgeon reported an inability to identify curve types and progression by observing the unclothed back alone.

Conclusions

This diagnostic study of adolescent patients screened for AIS found that the deep learning app had the potential for out-of-hospital accessible and radiation-free management of children with scoliosis, with comparable performance as spine surgeons experienced in AIS management.

Differences in Kinematic Changes From Self-Selected to Fast Speed Gait in Asymptomatic Adults With Radiological Signs of Femoro-Acetabular Impingement

Femoro-acetabular impingement (FAI) may present as alterations in the skeletal morphology of the hip. Repercussions of FAI can be witnessed in self-selected speed walking as well as physical exercise such as running or fast speed walking. The aim of this study was to investigate changes in kinematics at different gait speeds in subjects presenting with radiological findings invoking FAI. One hundred thirty asymptomatic adults underwent biplanar X-rays with a calculation of 3D hip parameters: acetabular anteversion, abduction and tilt, vertical center edge angle (VCE), femoral anteversion, neck-shaft angle, acetabular coverage of the femoral head, femoral head diameter and neck length. Parameters were classified according to FAI clinical thresholds. Two groups were created: Control group (63 subjects having up to one subnormal hip parameter in favour of FAI) and Radiographic FAI group (67 subjects having ≥2 subnormal hip parameters that might cause FAI). All subjects underwent 3D gait analysis at self-selected and fast speed, from which kinematic parameters were generated. Arithmetic differences between fast and self-selected speed gait were considered as gait changes. Subjects in the Radiographic FAI group had decreased acetabular tilt (24 vs. 19˚), anteversion (19 vs. 16˚), abduction (55 vs. 53˚), femoral anteversion (18 vs. 14˚) and increased VCE (29 vs. 33˚, all p<0.05), compared to controls. Changes from self-selected to fast speed showed that subjects in the Radiographic FAI group had lower range of motion (ROM) pelvic rotation (7 vs. 4˚) and ROM hip flexion/extension (10 vs. 7˚), reduced hip extension (-4 vs. -2˚) and step length (16 vs. 13 cm; all p<0.05). The Radiographic FAI group had decreased acetabular abduction, anteversion and femoral anteversion in favour of FAI. When adapting from self-selected to fast speed gait, the Radiographic FAI group seemed to limit pelvic rotation and hip flexion/extension resulting in a decrease in step length. These kinematic limitations were previously reported in subjects with symptomatic FAI. Gait analysis could be considered as a functional diagnostic tool to assess FAI along with radiological assessment.

Identification of Adolescent Menarche Status Using Biplanar X-ray Images: A Deep Learning-Based Method

The purpose of this study is to develop an automated method for identifying the menarche status of adolescents based on EOS radiographs. We designed a deep-learning-based algorithm that contains a region of interest detection network and a classification network. The algorithm was trained and tested on a retrospective dataset of 738 adolescent EOS cases using a five-fold cross-validation strategy and was subsequently tested on a clinical validation set of 259 adolescent EOS cases. On the clinical validation set, our algorithm achieved accuracy of 0.942, macro precision of 0.933, macro recall of 0.938, and a macro F1-score of 0.935. The algorithm showed almost perfect performance in distinguishing between males and females, with the main classification errors found in females aged 12 to 14 years. Specifically for females, the algorithm had accuracy of 0.910, sensitivity of 0.943, and specificity of 0.855 in estimating menarche status, with an area under the curve of 0.959. The kappa value of the algorithm, in comparison to the actual situation, was 0.806, indicating strong agreement between the algorithm and the real-world scenario. This method can efficiently analyze EOS radiographs and identify the menarche status of adolescents. It is expected to become a routine clinical tool and provide references for doctors' decisions under specific clinical conditions.

Relationship between spinal imbalance and knee osteoarthritis by using full-body EOS

BACKGROUND

Orthostatic state is maintained by harmonizing the spine, pelvis and lower extremities. In the past few decades, several studies have demonstrated the associations between spinal imbalance and generalized osteoarthritis. The compensatory mechanisms of pelvis translation and knee flexion, however, have not been fully assessed.

METHODS

A total of 213 volunteers, over 40 years of age, were recruited. Radiological measurements were performed by EOS imaging system. Pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), sagittal vertical axis (SVA), global tilt (GT), hip-knee-angle (HKA), knee flexion angle (KFA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA) were measured. On the basis of SRS-Schwab, the subjects were classified into decompensated group (PI-LL > 20°), compensated group(10° ≤ PI-LL ≤ 20°), and normal group (PI-LL < 10°). Differences in radiographic parameters among groups were evaluated. Data of Knee Society Score (KSS) and Oswestry Disability Index (ODI) score were collected via questionnaires.

RESULTS

Decompensated group showed larger pelvic parameters (PT) and low extremity parameters (LDFA, MPTA, HKA and KFA) than normal group (P < 0.05). Pelvic parameter was larger in the compensated group (median = 31°) compared to the normal group (median = 17°) (P < 0.05). There was no difference in low extremity parameters between the compensated and normal groups. At the sagittal plane, the radiological parameters of spine were greater in subjects with patellofemoral joint pain (PFP) than without PFP (P = 0.058). Higher PI-LL values were observed in women (P < 0.05).

CONCLUSIONS

A correlation between sagittal spinal imbalance and knee joint angles was recognized. The progression of knee and low back pain was associated with the severity of sagittal spinal imbalance. Pelvic retroversion was considered to be the probable compensatory mechanism.

Imaging Methods to Quantify the Chest and Trunk Deformation in Adolescent Idiopathic Scoliosis: A Literature Review

Background context: Scoliosis is a three-dimensional deformity of the spine with the most prevalent type being adolescent idiopathic scoliosis (AIS). The rotational spinal deformation leads to displacement and deformation of the ribs, resulting in a deformity of the entire chest. Routine diagnostic imaging is performed in order to define its etiology, measure curve severity and progression during growth, and for treatment planning. To date, all treatment recommendations are based on spinal parameters, while the esthetic concerns and cardiopulmonary symptoms of patients are mostly related to the trunk deformation. For this reason, there is a need for diagnostic imaging of the patho-anatomical changes of the chest and trunk in AIS. Aim: The aim of this review is to provide an overview, as complete as possible, of imaging modalities, methods and image processing techniques for assessment of chest and trunk deformation in AIS. Methods: Here, we present a narrative literature review of (1) image acquisition techniques used in clinical practice, (2) a description of various relevant methods to measure the deformity of the thorax in patients with AIS, and (3) different image processing techniques useful for quantifying 3D chest wall deformity. Results: Various ionizing and non-ionizing imaging modalities are available, but radiography is most widely used for AIS follow-up. A disadvantage is that these images are only acquired in 2D and are not effective for acquiring detailed information on complex 3D chest deformities. While CT is the gold standard 3D imaging technique for assessment of in vivo morphology of osseous structures, it is rarely obtained for surgical planning because of concerns about radiation exposure and increased risk of cancer during later life. Therefore, different modalities with less or without radiation, such as biplanar radiography and MRI are usually preferred. Recently, there have been advances in the field of image processing for measurements of the chest: Anatomical segmentations have become fully automatic and deep learning has been shown to be able to automatically perform measurements and even outperform experts in terms of accuracy. Conclusions: Recent advancements in imaging modalities and image processing techniques make complex 3D evaluation of chest deformation possible. Before introduction into daily clinical practice, however, there is a need for studies correlating image-based chest deformation parameters to patient-reported outcomes, and for technological advancements to make the workflow cost-effective.

Correlations Analysis of Different Pelvic Tilt Definitions: A Preliminary Study

Background: Pelvic tilt (PT) is described as the pelvic orientation along the transverse axis, yet 4 PT definitions were established based on radiographic landmarks: anterior pelvic plane (PTa), the center of femoral heads to sacral plate (PTm), pelvic outlet (PTh), and sacral slope (SS). These landmarks quantify a similar concept, yet understanding of their relationships is lacking, and their differences are sometimes ignored. Purpose: This study aimed to examine the correlations and differences of PT definitions for education and research purposes. Methods: This study reviewed 105 sagittal pelvic radiographs of patients (68 men and 37 women) awaiting hip surgery at a single clinic. Hip hardware and spine pathologies were examined for subgroup analysis. Two observers annotated 4 PTs in a gender-dependent manner and repeated it after 6 months. The linear regression model and intraclass correlation coefficient (ICC) were applied with a 95% confidence interval. Results: The SS showed no correlation to the other 3 PT definitions, except for females in the hip hardware subgroup (n = 17). PTm demonstrated very strong linear correlation to PTh (r > 0.9) under the linear model PTm = 0.951 × PTh - 68.284. Conclusion: The PTm and PTh can be calculated from each other under a simple linear regression equation, which enables comparisons between them. SS presented poor correlations to the other PT parameters, except for the female subgroup with hip implant that required further analysis; PTa-related comparisons showed high anatomical variations between patients.

Validation of a Novel Method of Measuring Cup Orientation using BiPlanar Simultaneous Radiographic Images

BACKGROUND

Accurate acetabular component positioning is paramount to the success of total hip arthroplasty. Two-dimensional imaging alone remains a popular tool for implant position assessment despite known limitations. We investigated the accuracy of a novel method for assessing acetabular component position based upon orthogonal simultaneous biplanar Xray images.

METHODS

There were forty consecutive patients who had a pre-existing total hip arthroplasty (THA) on the contralateral side who underwent both computed tomography (CT) and simultaneous orthogonal biplanar radiographic scans for pre-operative planning of THA. The operative inclination (OI) and operative anteversion (OA) of the acetabular cup were calculated by a new measurement method using the biplanar simultaneous scans. Those measurements were compared to measurement of the cup orientation on CT. The measurements were made by two independent observers. Interobserver correlation coefficients were calculated between the two observers to measure reliability.

RESULTS

The mean error in OA measurement of the acetabular cup between simultaneous orthogonal biplanar radiographic and CT imaging was 0.5° (Standard Deviation (SD): 1.9°, minimum -4.0°, maximum 5.0°), the mean error in OI was 0.0° (SD: 1.7°, minimum -5.0°, maximum 4.0°). The average absolute error was 1.5° for OA, and 1.2° for OI. Interobserver correlation coefficient was 0.83 for OA and 0.93 for OI.

CONCLUSION

The novel method of measuring cup orientation using simultaneous biplanar radiographic scans utilized in this study was accurate and reproducible between observers compared to CT measurements.

Osteoarthritis Year in Review 2022: Imaging

PURPOSE

This narrative review summarizes original research focusing on imaging in osteoarthritis (OA) published between April 1^st 2021 and March 31^st 2022. We only considered English publications that were in vivo human studies.

METHODS

The PubMed, Medline, Embase, Scopus, and ISI Web of Science databases were searched for "Osteoarthritis/OA" studies based on the search terms: "Radiography", "Ultrasound/US", "Computed Tomography/CT", "DXA", "Magnetic Resonance Imaging/MRI", "Artificial Intelligence/AI", and "Deep Learning". This review highlights the anatomical focus of research on the structures within the tibiofemoral, patellofemoral, hip, and hand joints. There is also a noted focus on artificial intelligence applications in OA imaging.

RESULTS

Over the last decade, the increasing trend of using open-access large databases has reached a plateau (from 17 to 37). Compositional MRI has had the most prominent use in OA imaging and its biomarkers have been used in the detection of preclinical OA and prediction of OA outcomes. Most noteworthy, there has been an accelerated rate of publications on the implications of artificial intelligence, used in developing prediction models and performing trabecular texture analysis, in OA imaging (from 17 to 154).

CONCLUSIONS

While imaging has maintained its key role in OA research, publication trends have shown an emphasis on the integration of AI. During the past year, MRI has maintained the highest prevalence in usage while US and CT remain as readily available modalities. Finally, there has been a notable uptake in the development and validation of AI techniques used to perform texture analysis and predict OA progression.

ASSESSMENT OF PCXMC MONTE CARLO SIMULATIONS IN SLOT-SCANNING-BASED EXAMINATIONS: COMPARISON WITH IN-PHANTOM THERMOLUMINESCENT DOSIMETRY

Slot-scanning technology is nowadays a valid solution for the follow-up of chronic musculoskeletal disorders on children and adolescent patients, but there is no commercial software designed for simulating this X-ray beam geometry. PC Program for X-ray Monte Carlo (PCXMC) is a widespread Monte Carlo software developed for dose computation in projection radiography. In this study, experimental measurements were performed to evaluate its applicability in examinations with a slit-beam device. Physical phantoms corresponding to an adult and a 5-y-old child with calibrated thermoluminescent dosemeters were used for experiments. Different simulation approaches were investigated. Differences between measured and calculated organ doses ranged from -95 to 67% and were statistically significant for almost all organs. For both patients, PCXMC underestimated the effective dose of about 25%. This study suggests that PCXMC is not suited for organ dose evaluation in examinations with slot-scanning devices. It is still a useful tool for effective dose estimation when a proper correction factor is applied.

Semi-XctNet: Volumetric images reconstruction network from a single projection image via semi-supervised learning

Deep learning networks have achieved remarkable progress in various tasks of medical imaging. Most of the recent success in computer vision highly depend on large amounts of carefully annotated data, whereas labelling is arduous, time-consuming and in need of expertise. In this paper, a semi-supervised learning method, Semi-XctNet, is proposed for volumetric images reconstruction from a single X-ray image. In our framework, the effect of regularization on pixel-level prediction is enhanced by introducing a transformation consistent strategy into the model. Furthermore, a multi-stage training strategy is designed to ameliorate the generalization performance of the teacher network. An assistant module is also introduced to improve the pixel quality of pseudo-labels, thereby further improving the reconstruction accuracy of the semi-supervised model. The semi-supervised method proposed in this paper has been extensively validated on the LIDC-IDRI lung cancer detection public data set. Quantitative results show that SSIM (structural similarity measurement) and PSNR (peak signal noise ratio) are 0.8384 and 28.7344 respectively. Compared with the state-of-the-arts, Semi-XctNet exhibits excellent reconstruction performance, thus demonstrating the effectiveness of our method on the task of volumetric images reconstruction network from a single X-ray image.

Looking at the spine in controlled Acromegaly

Skeletal fragility with high risk of vertebral fractures (VFs) is an emerging complication of growth hormone (GH) hypersecretion. VFs often coexist with spine arthropathy and both clinical conditions negatively impact on quality of life of acromegalic subjects. Management of spine osteopathy and arthropathy in acromegaly could be challenging since both complications can persist or even progress after biochemical control of disease. This article analyzes the latest evidence about possible pathophysiological links between VFs and spine arthropathy in active and controlled acromegaly, as well as the diagnostic and therapeutic aspects concerning the holistic management of acromegalic osteo-arthropathy.

Interobserver reliability of biplanar radiography is unaffected by clinical factors relevant to individuals at risk of pathological lower limb torsion

BACKGROUND

Assessments of lower limb torsion are ubiquitous in clinical gait analysis practice as pathologic lower limb rotational deformity may contribute to gait abnormalities, anterior knee pain, as well as other debilitating conditions. Understandably, the overall utility of any torsional assessment is dependent on the measurement method's intrinsic accuracy, precision, and robustness to clinical interference factors. Recently, biplanar radiography (BPR) measurements of torsion have been shown to be both accurate and precise, but the robustness of BPR to potential interference factors is unknown.

RESEARCH QUESTION

How robust are BPR lower limb torsional assessments to six potential interference factors: amount of torsion, skeletal maturity, radiograph quality, prior osteotomy, presence of implants, and observer training background and experience?

METHODS

In this retrospective cohort study, four observers of diverse backgrounds and experience generated digital 3D reconstructions of 44 lower limbs using BPR images obtained during standard of care visits (age range 7-35 years). From each reconstruction, four lower limb torsional parameters were computed: femoral torsion, femorotibial rotation, tibial torsion, and transmalleolar axis equivalent. The mean absolute deviation (MAD) of each torsional parameter - calculated across the four observers - was used as the measure of reliability and tested against all interference factors.

RESULTS

Results demonstrated that the average MAD was 2.1 degrees for femoral torsion, 3.0 degrees for transmalleolar axis equivalent, 3.8 degrees for femorotibial rotation, and 4.7 degrees for tibial torsion. None of the six potential interference factors were found to systematically influence BPR reliability across all four torsional parameters. Of the factors found to statistically influence one or more torsional parameter, none affected MAD values to a clinically meaningful extent.

SIGNIFICANCE

In addition to being accurate and precise, BPR appears to be robust to several clinical factors relevant to children and young adults with or at risk for pathological lower limb torsion.

Reliability of Preoperative Supine Versus Bending Radiographs in Estimating the Structural Nature of Curves in EOS

BACKGROUND

The study sought to evaluate the utility of a single supine radiograph in determining curve flexibility in early-onset scoliosis (EOS) patients.

METHODS

EOS patients with upright (standing/seated), supine, and side-bending radiographs who underwent spinal deformity surgery were identified. Coronal parameters included: proximal thoracic (PT) curve, main thoracic (MT) curve, and thoracolumbar/lumbar (TL/L) curve. Each radiograph was measured twice by 2 different raters. Correlation coefficients were utilized to investigate associations between the different radiographs. Interrater Correlation Coefficient (ICC) assessed intrarater and interrater reliability.

RESULTS

Thirty-seven EOS patients were identified (age at diagnosis: 7.0±2.9 y, preoperative age: 13.0±2.9 y; 73% female; etiologies: 54% idiopathic, 30% syndromic, and 16% neuromuscular). Supine PT and MT curve measurements were highly associated with corresponding side-bending measurements (PT: r=0.75, P<0.001; MT: r=0.80, P<0.001), and TL/L curves were very highly associated (TL/L: r=0.92, P<0.001). The mean absolute differences between supine and side-bending measurements were PT: 11.3±7.8 degrees, MT: 14.8±8.3 degrees, and TL/L: 16.2±7.6 degrees, where the side-bending was on average smaller than the supine measurement. The intrarater reliabilities were excellent, with an ICC ranging from 0.93 to 0.96 for side-bending films and 0.94 to 0.97 for supine films. The interrater reliability was excellent with ICC value of 0.88 for side-bending films and 0.93 for supine films.

CONCLUSIONS

A single, preoperative supine radiograph was highly predictive of side-bending radiographs in patients with EOS. Supine curves measured an average of 15 degrees larger than bending curves in the MT and TL/L region. A single supine film may eliminate the need for effort-related, dual side-bending radiographs.

LEVEL OF EVIDENCE

Level II-retrospective study.

Growth modulation for angular knee deformities: a practical guideline

PURPOSE OF REVIEW

This study aimed to review the established concepts and advances related to growth modulation for treating knee angular deformities. Although they are considered well tolerated procedures, careful indications and accurate techniques are necessary to ensure good results.

RECENT FINDINGS

In addition to general clinical and radiographic evaluations, new tools such as two-dimensional low-dose radiography and gait analysis have been used to clarify angular and torsional combinations and the impact of mild angulations on the knee joint. Temporary epiphysiodesis is commonly the choice, and it can be performed with different implants such as staples, tension band plates (TBP), percutaneous transphyseal screws (PETS), sutures, and screws.

SUMMARY

Considering its principles, TBP has been preferred for younger children. Cost can be a limitation, and research for alternative implants such as screws and nonabsorbable sutures indicate they might be an alternative in the future. In adolescents, PETS becomes an attractive alternative; however, its reversible character has been controversial, and further studies are needed to establish limits in younger patients.

Clinical application of EOS imaging system: a scoping review protocol

OBJECTIVE

The objective of this scoping review is to examine and map the existing literature on the clinical application of the EOS imaging system and to identify related evidence gaps.

INTRODUCTION

The EOS imaging system was originally developed to conduct imaging for medical conditions, such as scoliosis and anisomelia. However, recent research suggests that the modality has other clinical uses that may benefit patients via reduced radiation dose and, thus, improve patient safety.

INCLUSION CRITERIA

This scoping review will consider all quantitative study designs, including systematic reviews and meta-analyses. Imaging phantom studies and conference abstracts will be excluded.

METHODS

Databases that will be searched include Embase, MEDLINE, CINAHL Complete, Scopus, Cochrane Library, Academic Search Premier, and OpenGrey. Relevant secondary material will be identified using citation searching (backwards and forwards) of included studies through Google Scholar. In addition, we will search by author name where more than 3 included studies from the same first author are identified. Articles published from 2003 in English, Danish, Norwegian, Swedish, French, and German will be included. Two independent reviewers will perform title/abstract screening, followed by full-text screening. Data extraction will include study type and design, age of participants, anatomical/physiological region, pathology, clinical endpoint, outcome measures, sample size, and clinical application. Data will be presented in tabular format and as a narrative summary.

REVIEW REGISTRATION NUMBER

Open Science Framework https://osf.io/yc85j/.

Femoral Version May Impact Hip Arthroscopy Outcomes in Select Patient Populations: A Systematic Review

PURPOSE

To provide further clarity regarding the management of patients with abnormal femoral version in the setting of hip arthroscopy and will discuss the definition of femoral version, the diagnostic and clinical evaluation of abnormal femoral version, and several described measurement techniques.

METHODS

A systematic review was conducted in literature published before August 2021 that measured femoral version and reported patient-reported outcomes measures or rates of subsequent procedures following hip arthroscopy. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed and the electronic databases, PubMed, OvidMedLine, Scopus, and Web of Science were searched. Two blinded reviews screened and evaluated data quality using the Newcastle-Ottawa Scale.

RESULTS

Eighteen studies were included with 11 studies reporting patient outcomes and 7 studies reporting rates of subsequent procedures. The most commonly used definition of femoral version was 5° to 20° of femoral anteversion. Computed tomography scan was the most commonly used imaging modality. The majority of studies (7 of 11) demonstrated that femoral version does not have an impact on patient-reported outcomes measures and is not predictive of clinically meaningful improvement scores. However, in select studies, patients with femoral retroversion were found to experience slightly inferior outcomes following hip arthroscopy for femoroacetabular impingement. While femoral retroversion may be a risk factor for subsequent procedures, 3 of 7 studies refute this claim. Although in patients with borderline hip dysplasia, excessive femoral anteversion led to greater rates of subsequent hip procedures.

CONCLUSIONS

While the majority of studies show that femoral version does not have an impact on patient-reported outcomes following hip arthroscopy, those with femoral retroversion and with excessive anteversion with coexisting borderline hip dysplasia need to be educated on their increased risk of subsequent operation. Ultimately, this review suggests that clinical improvement can likely be achieved regardless of femoral version.

LEVEL OF EVIDENCE

IV; systematic review of Level I-IV studies.

Is impaired lung function related to spinal deformities in patients with adolescent idiopathic scoliosis? A systematic review and meta-analysis-SOSORT 2019 award paper

PURPOSE

Some teenagers with adolescent idiopathic scoliosis (AIS) display compromised lung function. However, the evidence regarding the relations between pulmonary impairments and various spinal deformity parameters in these patients remains unclear, which affects clinical management. This systematic review and meta-analysis aimed to summarize the associations between various lung function parameters and radiographic features in teenagers with AIS.

METHODS

A search of PubMed, Embase, PEDro, SPORTDiscus, CINAHL, Cochrane Library, and PsycINFO (from inception to March 14, 2022) without language restriction. Original studies reporting the associations between lung function and spinal deformity in patients with AIS were selected. Independent reviewers extracted data and evaluated the methodological quality of the included studies according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pearson correlation and 95% confidence intervals were calculated using random-effects meta-analysis.

RESULTS

Twenty-seven studies involving 3162 participants were included. Limited-quality evidence supported that several spinal parameters were significantly related to lung function parameters (e.g., absolute value and percent of the predicted forced vital capacity (FVC; %FVC), forced expiratory volume in one second (FEV₁; %FEV₁), and total lung capacity (TLC; %TLC)) in AIS patients. Specifically, meta-analyses showed that main thoracic Cobb angles in the coronal plane were significantly and negatively related to FVC (r =  - 0.245), %FVC (r =  - 0.302), FEV₁ (r =  - 0.232), %FEV₁ (r =  - 0.348), FEV₁/FVC ratio (r =  - 0.166), TLC (r =  - 0.302), %TLC (r =  - 0.183), and percent predicted vital capacity (r =  - 0.272) (p < 0.001). Similarly, thoracic apical vertebral rotation was negatively associated with %FVC (r =  - 0.215) and %TLC (r =  - 0.126) (p < 0.05). Conversely, thoracic kyphosis angles were positively related to %FVC (r = 0.180) and %FEV₁ (r = 0.193) (p < 0.05).

CONCLUSION

Larger thoracic Cobb angles, greater apical vertebral rotation angle, or hypokyphosis were significantly associated with greater pulmonary impairments in patients with AIS, although the evidence was limited. From a clinical perspective, the results highlight the importance of minimizing the three-dimensional spinal deformity in preserving lung function in these patients. More research is warranted to confirm these results.

Does Laminectomy Affect Spino-Pelvic Balance in Lumbar Spinal Stenosis? A Study Based on the EOS X-Ray Imaging System

PURPOSE

Lumbar spinal stenosis (LSS) is a degenerative disorder causing the forward bending of the trunk and pelvic retroversion with the consequent loss of lumbar lordosis; surgical treatment is intended to enlarge the canal and foramina and decompress the nerve roots. The purpose of our study is to determine whether and to what extent facet-sparing laminectomy affects the spino-pelvic balance.

METHODS

The spino-pelvic balance of 26 patients was analysed before and after surgery through the EOS X-ray Imaging System. The following parameters were considered: thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT) and sacral slope (SS). Clinical data were expressed in numeric values according to the Oswestry Disability Index (ODI), the visual analogue scale (VAS) and the modified Japanese Orthopaedic Association (mJOA) scoring system.

RESULTS

Significant SS decreases and PT increases were noticed after surgery, without modification in LL, axial vertebral rotation (AVR) and the general alignment. Pain and disability had a significant improvement, as represented by a decrease in scores on the VAS and ODI scales and an increase in scores on the mJOA functional scale.

CONCLUSION

The most important parameter seems to be a congruence between pelvic and spinal parameters, which achieves an economic posture with the physiologic position of the axis of gravity. According to the literature, a standard sagittal balance (SB) has not been defined.

Radiation in Adolescent Idiopathic Scoliosis Management: Estimated Cumulative Pre-Operative, Intra-Operative, and Post-Operative Exposure

Background

Adolescent Idiopathic Scoliosis (AIS) is the most common type of scoliosis affecting adolescents, with approximately 2-4% of children being diagnosed. Crucial to the diagnosis and management are radiographic imaging, which allow physicians to assess and treat - from initial visits through surgical planning and post-operative management. While initial stages require low levels of exposure to radiation, via x-rays, as patients progress in disease severity exposure becomes larger with pre-operative, intra-operative and post-operative CT scans. While many studies have evaluated exposure during AIS treatment, few have assessed the cumulative radiation exposure adolescents receive during their evaluation. The purpose of our study is to complete a comprehensive review on cumulative radiation exposure and determine what stages in AIS treatment expose patients to the highest level of radiation over a duration of 2 years.

Methods

A retrospective chart review of 109 AIS cases (29M, 80F), mean age 14.9 ± 2.3 years was completed to assess and quantify each imaging modality used. Employing a radiation detector, each imaging modality was then assessed, and estimated radiation exposures were determined. Statistical analysis was completed utilizing averaged patient exposures during each selected period in AIS management.

Results

Mean estimated radiation doses (StDev) were 60.94 mrem (±0.609 mrem) for two x-rays (full-length AP and lateral radiograph of the entire spine), 12.92 mrem (±1.292 mrem) for each fluoroscopy exposure, and 1340.60 mrem (±13.406 mrem) per CT scan. Based on these values, estimated subject exposures were calculated. The total estimated radiation exposure over a 2-year period was 5572.74 mrem (±1428.88 merm) or 2786.37 mrem (±714.43 mrem) per year.

Conclusion

The two-year cumulative radiation exposure is below the recommended exposure by Nuclear Regulatory Commission and OSHA. As expected, CT exposure presents the largest radiation exposure to patients with AIS throughout their operative management.

Level of Evidence

III, retrospective study.

Relationship between degenerative scoliosis and lower extremity mechanical parameters based on EOS imaging system

OBJECTIVE

This study aimed to assess the correlation between coronal imbalance and lower-limb physiological parameters in degenerative scoliosis using the biplanar whole body imaging system (EOS).

MATERIALS AND METHODS

A total of 101 successive EOS images were selected between January 2018 and December 2021. Of the selected images, 63 patients were in the degenerative scoliosis group (DSG) and 38 patients were in the control group (CG). Two independent observers performed measurements of the parameters and compared the two groups.

RESULTS

Among parameters examined, significant inter-group differences were found for coronal pelvic tilt angle (CPT), bilateral femoral length difference (ΔFL), and bilateral total lower limb length (ΔTL) difference. Additionally, the knee and ankle joints had more severe degeneration on the main curved side in patients with degenerative scoliosis. In the left curved group, 18 (42.86%) and 24 (57.1%) patients had more severe degeneration in the left knee and left ankle, respectively. In the right lateral bending group, 13 (61.9%) and 14 (66.7%) patients had more severe degeneration in the right knee and right ankle, respectively. Statistical differences were found in the degree of degeneration in both knee and ankle joints bilaterally.

CONCLUSION

This study showed that biomechanical parameters of the lower limbs are affected in cases of degenerative scoliosis with altered coronal balance. The lower limb on the main curve side became shorter compared to its counterpart, and joint degeneration of the knee and ankle joints became more severe.

Reliability of the pelvis and femur anatomical landmarks and geometry with the EOS system before and after total hip arthroplasty

Bi-plane X-ray provides 3D measurements of the lower limb based on the identification of anatomical landmarks in sagittal and frontal X-rays. In clinical practice, such measurements involve multiple operators and sessions. This study aimed at evaluating the reliability of anatomical landmarks identification and geometric parameters of the pelvis and femur measured with bi-plane X-rays before and after total hip arthroplasty (THA). Twenty-eight patients undergoing primary THA were selected retrospectively. Two operators performed three reconstructions for each patient before and after THA. Intraclass correlation (ICC) and smallest detectable change (SDC) were computed for intra-operator, inter-operator, and test-retest conditions. Most anatomical landmark positions had good to excellent SDC (< 5 mm) apart from the centre of the sacral slope, greater trochanter, and anterior superior iliac spines (up to 7.1, 16.9, and 21.5 mm respectively). Geometric parameters had moderate to excellent SDC, apart from femoral and stem torsion, pelvic incidence, and APP inclination with poor SDC (9-12°). The sagittal view had significantly higher measurement errors than the frontal view. Test-retest and inter-operator conditions had no significant differences suggesting a low influence of patient posture. Osteoarthritis and the presence of implants did not seem to influence reliability and measurement error. This study could be used as a reference when assessing lower limb structure with bi-plane X-rays.

Influence of implantation of a total hip endoprosthesis on the ipsilateral leg alignment: the effect of sex and dysplasia of the hip

INTRODUCTION

Differences in leg and hip morphology exist between sexes and developmental hip dysplasia is known to alter proximal femoral morphology. The purpose of this study was to determine whether existing differences in leg alignment due to sex or developmental hip dysplasia have an effect on changes in leg alignment after total hip arthroplasty.

MATERIALS AND METHODS

30 hip osteoarthritis patients underwent biplanar full-length radiography in the standing position preoperatively and 3 months after total hip arthroplasty. Differences in leg alignment between men and women and between patients with primary hip osteoarthritis and patients with developmental dysplasia before and after surgery were tested using a general linear model for repeated measures.

RESULTS

Implantation of a hip prosthesis had no differential effect on ipsilateral leg alignment in patients with hip osteoarthritis due to dysplasia and in patients with primary hip osteoarthritis. However, patients with hip osteoarthritis due to dysplasia had a 2.1° higher valgus both before and after surgery. After total hip arthroplasty, women had a significantly greater increase in varus angle (1.6° vs. 0°) and femoral offset (10.5 vs. 4.6 mm) compared with men. Because the change in acetabular offset was smaller (2.2 vs. 6.2 mm), the global femoral offset was only increased in women. Femoral torsion was constant for men (15.0° and 16.5°), whereas femoral torsion was significantly reduced in women (19.9° and 13.2°).

CONCLUSIONS

Hip arthroplasty has a greater effect on leg axis in women than in men. The axial leg alignment of women could change from a natural valgus to a varus alignment. Therefore, surgeons should consider the effects of total hip arthroplasty on leg alignment in patients with hip osteoarthritis. Whether these changes in leg alignment are also clinically relevant and lead to premature medial or lateral knee osteoarthritis should be investigated in future work.

TRIAL REGISTRATION

This study was registered with DRKS (German Clinical Trials Register) under the number DRKS00015053. Registered 1st of August 2018.

Spinopelvic Adaptations in Standing and Sitting Positions in Patients With Adult Spinal Deformity

Purpose

To describe spinopelvic adaptations in the standing and sitting positions in patients with adult spinal deformity (ASD).

Methods

Ninety-five patients with ASD and 32 controls completed health-related quality of life (HRQOL) questionnaires: short form 36 (SF36), Oswestry Disability Index (ODI), and visual analog scale (VAS) for pain. They underwent biplanar radiography in both standing and sitting positions. Patients with ASD were divided into ASD-front (frontal deformity Cobb > 20°, n = 24), ASD-sag (sagittal vertical axis (SVA) > 50 mm, pelvic tilt (PT) > 25°, or pelvic incidence (PI)-lumbar lordosis (LL) > 10°, n = 40), and ASD-hyper thoracic kyphosis (TK >60°, n = 31) groups. Flexibility was defined as the difference (Δ) in radiographic parameters between the standing and sitting positions. The radiographic parameters were compared between the groups. Correlations between HRQOL scores were evaluated.

Results

All participants increased their SVA from standing to sitting (ΔSVA<0), except for patients with ASD-sag, who tended to decrease their SVA (78-62 mm) and maximize their pelvic retroversion (27-40° vs 10-34° in controls, p<0.001). They also showed reduced thoracic and lumbar flexibility (ΔLL = 3.4 vs 37.1°; ΔTK = −1.7 vs 9.4° in controls, p<0.001). ASD-hyperTK showed a decreased PT while sitting (28.9 vs 34.4° in controls, p<0.001); they tended to decrease their LL and TK but could not reach values for controls (ΔLL = 22.8 vs 37.1° and ΔTK = 5.2 vs 9.4°, p<0.001). The ASD-front had normal standing and sitting postures. ΔSVA and ΔLL were negatively correlated with the physical component scale (PCS of SF36) and ODI (r = −0.39 and r = −0.46, respectively).

Conclusion

Patients with ASD present with different spinopelvic postures and adaptations from standing to sitting positions, with those having sagittal malalignment most affected. In addition, changes in standing and sitting postures were related to HRQOL outcomes. Therefore, surgeons should consider patient sitting adaptations in surgical planning and spinal fusion. Future studies on ASD should evaluate whether physical therapy or spinal surgery can improve sitting posture and QOL, especially for those with high SVA or PT.

The Adolescent Spine

Adolescent idiopathic scoliosis (AIS) is the most characteristic disorder of the adolescent spine. It is a three-dimensional (3D) disorder that occurs from 10 years of age and comprises 90% of all idiopathic scolioses. Imaging plays a central role in the diagnosis and follow-up of patients with AIS. Modern imaging offers 3D assessment of scoliosis with less radiation exposure. Imaging helps rule out occult conditions that cause spinal deformity. Various imaging methods are also used to assess skeletal maturity in patients with AIS, thus determining the growth spurt and risk of progression of scoliosis. This article provides a brief overview of the pathophysiology, biomechanics, clinical features, and modern imaging of AIS relevant to radiologists in clinical settings.