Hip Pain: Imaging of Intra-articular and Extra-articular Causes

Hip pain is a common and complex clinical entity. The causes of hip injuries in athletes are many and diverse, requiring efficient, accurate diagnosis for proper management. Imaging is an important step in the clinical evaluation of hip pain, and familiarity with multiple imaging modalities as well as characteristic imaging findings is a helpful tool for sports medicine clinicians. This article discusses imaging recommendations and gives imaging examples of common causes of intra-articular and extra-articular hip pain including femoroacetabular impingement, labral tears, cartilage defects, ligamentum teres injuries, snapping hip syndrome, femoral stress injuries, thigh splints, athletic pubalgia, avulsion injuries, and hip dislocation.

Artificial Intelligence to Automatically Assess Scan Quality in Hip Ultrasound

PURPOSE

Since it is fast, inexpensive and increasingly portable, ultrasound can be used for early detection of Developmental Dysplasia of the Hip (DDH) in infants at point-of-care. However, accurate interpretation\is highly dependent on scan quality. Poor-quality images lead to misdiagnosis, but inexperienced users may not even recognize the deficiencies in the images. Currently, users assess scan quality subjectively, based on image landmarks which are prone to human errors. Instead, we propose using Artificial Intelligence (AI) to automatically assess scan quality.

METHODS

We trained separate Convolutional Neural Network (CNN) models to detect presence of each of four commonly used ultrasound landmarks in each hip image: straight horizontal iliac wing, labrum, os ischium and midportion of the femoral head. We used 100 3D ultrasound (3DUS) images for training and validated the technique on a set of 107 3DUS images also scored for landmarks by three non-expert readers and one expert radiologist.

RESULTS

We got AI ≥ 85% accuracy for all four landmarks (ilium = 0.89, labrum = 0.94, os ischium = 0.85, femoral head = 0.98) as a binary classifier between adequate and inadequate scan quality. Our technique also showed excellent agreement with manual assessment in terms of Intraclass Correlation Coefficient (ICC) and Cohen's kappa coefficient (K) for ilium (ICC = 0.81, K = 0.56), os ischium (ICC = 0.89, K = 0.63) and femoral head (ICC = 0.83, K = 0.66), and moderate to good agreement for labrum (ICC = 0.65, K = 0.33).

CONCLUSION

This new technique could ensure high scan quality and facilitate more widespread use of ultrasound in population screening of DDH.

Developmental hip dysplasia and hip ultrasound frequency in a large American payer database

Developmental dysplasia of the hip (DDH) is an important contributor to musculoskeletal morbidity, but effective strategies to screen for DDH remain controversial. The current utilization of hip ultrasound (US) screening for DDH in the United States is not defined. This study utilized Optum's de-identified Clinformatics® Data Mart, a large commercial and Medicare Advantage claims database. The frequency of DDH and hip US utilization was estimated using billing data on an average of 2.9 million relevant beneficiaries included annually from 2007 through 2017. A total of 6806 DDH cases were identified with an average annual prevalence of 1.7 per 1000 infants, which was stable during the study period. Girls were more likely to be screened and diagnosed with DDH, comprising 72% of DDH cases with an OR of 2.55 (95% CI 2.42-2.69), p < 0.001. Hip US screening was employed in 0.9% of the infant population on average but increased substantially from 2007 (0.4%) to 2017 (2.2%). Most common billing diagnoses included hip deformity (27.4%), breech delivery (20.4%), and physical exam abnormality (17.7%). The average imaging costs per patient for all screened children was $108.94. Insurance claims reflect the current American practice of selective hip US with relative adherence to American Academy of Pediatrics guidelines based on reported diagnoses. While hip US utilization increased during the study period, prevalence of DDH diagnoses did not increase. Our results suggest that expansion of hip US screening may not effectively increase DDH detection although further investigation is needed to ascertain optimal screening strategies to improve patient outcomes.

Impact of scan quality on AI assessment of hip dysplasia ultrasound

AIMS

Early diagnosis of developmental dysplasia of the hip (DDH) using ultrasound (US) is safe, effective and inexpensive, but requires high-quality scans. The effect of scan quality on diagnostic accuracy is not well understood, especially as artificial intelligence (AI) begins to automate such diagnosis. In this paper, we developed a 10-point scoring system for reporting DDH US scan quality, evaluated its inter-rater agreement and examined its effect on automated assessment by an AI system-MEDO-Hip.

METHODS

Scoring was based on iliac wing straightness and angulation; visibility of labrum, os ischium and femoral head; motion; and other artifacts. Four readers from novice to expert separately scored the quality of 107 scans with this 10-point scale and with holistic grading on a scale of 1-5. MEDO-Hip interpreted the same scans, providing a diagnostic category or identifying the scan as uninterpretable.

RESULTS

Inter-rater agreement for the 10-point scale was significantly higher than holistic scoring ICC 0.68 vs 0.93, p < 0.05. Inter-rater agreement on the categorisation of individual features, by Cohen's kappa, was highest for os ischium (0.67 ± 0.06), femoral head (0.65 ± 0.07) and iliac wing (0.49 ± 0.12) indices, and lower for the presence of labrum (0.21 ± 0.19). MEDO-Hip interpreted all images of a quality > 7 and flagged 13/107 as uninterpretable. These were low-quality images (3 ± 1.2 vs. 7 ± 1.8 in others, p < 0.05), with poor visualization of the os ischium and noticeable motion. AI accuracy in cases with quality scores <  = 7 was 57% vs. 89% on other cases, p < 0.01.

CONCLUSION

This study validates that our scoring system reliably characterises scan quality, and identifies cases likely to be misinterpreted by AI. This could lead to more accurate use of AI in DDH diagnosis by flagging low-quality scans likely to provide poor diagnosis up front.

Early neonatal universal ultrasound screening for developmental dysplasia of the hip: a single institution observational study

OBJECTIVE

We evaluated the effect of early universal ultrasound (US) screening program for developmental dysplasia of the hip (DDH).

METHODS

A total of 21,676 newborns between 2006 and 2015 were included in the study. All hips were examined by US within the first week of life. The incidence of sonographic hip-types according to the Graf method was analyzed, and then followed prospectively. Risk factors for DDH and treatment measures were also recorded, together with the number of first surgical procedures before the age of three years.

RESULTS

Overall, 92.5% of hips were mature (Graf types Ia, Ib) at first examination, 7.2% were mature (Graf type IIa) and 0.3% were pathological (Graf types IIc to IV). A total of 146 pathological hips were detected in 118 of newborns (0.6%). Only 0.26% of screened population was treated with an orthosis. The rate of first surgical procedures and the rate of late detected DDH were 0.23 and 0.09 per 1000 live births, respectively. Regarding risk factors, positive family history, female gender, breech presentation, and high birth weight were significantly more common in newborns with pathological hips.

CONCLUSION

Early neonatal universal US screening using Graf method is recommended to timely detect DDH and to provide the optimal conservative approach of management. It seems to be effective in reducing the overall treatment rate, together with the rate of surgical procedures and late detected cases.

Developmental dysplasia of the hip: real world data from a retrospective analysis to evaluate the effectiveness of universal screening

AIMS

Developmental dysplasia of the hip is an important cause of disability in children and young adult and it also has a significant socio-economic impact in our society. The main objective of our study is to evaluate, in our hospital, the effectiveness of a universal ultrasound screening protocol and to assess the general knowledge about the theme of pediatricians and neonatologists.

METHODS

Retrospective study of infants born from January 2016 to April 2019, evaluated with hip ultrasound (Graf method). Risk factors assessed were female gender, breech presentation at birth, positive family history and twin birth. For the secondary objective, an anonymous and validated questionnaire was distributed to all pediatricians and neonatologists.

RESULTS

Among the 4000 hips analyzed, on ultrasound examination, 98.8% hips resulted mature or immature but appropriate for age, while 1,2% hips were pathological. Analyzing the mature or immature hips, 2,4% were positive on clinical examination and 97,6% were negative. In relation to ultrasound pathological hips, 33,3% have positive clinical examination, while 66,7% negative. From the analysis of risk factors a significant association emerged between female sex, breech presentation and family history with the ultrasound pathological findings. The results of Survey showed that inadequate training about developmental dysplasia of the hip is done during medical school.

CONCLUSIONS

A universal ultrasound screening allowed us to identify developmental dysplasia of the hip in a number of children with normal clinical examination and no risk factors. Specific training courses should be implemented regarding Developmental Dysplasia of the Hip for neonatologists and pediatricians.

Hip: Anatomy and US technique

Ultrasound (US) has always had a relatively limited role in the evaluation of the hip due to the deep location of this joint. However, many hip diseases are well detectable at US, but before approaching such a study it is necessary to be thoroughly familiar with the normal anatomy and related US images. The study technique is particularly important as optimization of various parameters is required, such as probe frequency, focalization, positioning of the probe, etc. Also the patient's position is important, as it varies according to the area requiring examination. For the study of the anterior structures, the patient should be in the supine position; for the medial structures, the leg should be abducted and rotated outward with the knee flexed; for the lateral structures, the patient should be in the controlateral decubitus position; for the posterior structures the patient must be in the prone position. US study of the hip includes assessment of the soft tissues, tendons, ligaments and muscles, and also of the bone structures, joint space and serous bursae. The purpose of this article is to review the normal anatomy of the hip as well as the US anatomy of this joint.