Comparison of sonographic and radiographic findings among children with suspected forearm fractures at Moi Teaching and Referral Hospital, Eldoret Kenya

Abstract

Background: Forearm fractures are the commonest injuries in children and account for about 36.4% of all paediatric injuries. Plain radiography is the gold standard in the diagnosis of fractures. However, ionising radiation is harmful in children and have up to ten times increased risk of morbidity, making their highly dividing cells susceptible to its undesirable effects. About 50% of the suspected forearm fractures sent for x-ray, are found to be normal. Ultrasonography is radiation free, portable and a quick tool to use. This makes it a safe tool to use hence a larger area can be imaged to know where the exact fracture site is, especially for younger children since they cannot express themselves well. Various studies have shown that ultrasonography is capable of accurate diagnosis and can be done in resource poor setups. Objectives: To describe and compare the sonographic and radiographic findings among children with suspected forearm fractures in Moi Teaching and Referral Hospital (MTRH). Methods: This was a descriptive cross-sectional study conducted at the MTRH from April 2021 to March 2022. Consecutive sampling method was used to enrol 373 participants aged less than 18 years with suspected forearm fractures following trauma. Ethical approval was sought. Data collection tool was used using structured questionnaires. Appropriate analgesia was administered in the Emergency Department to all patients with suspected forearm fractures before sending them for imaging. Adequate ultrasound gel was used to reduce firm contact of the transducer with the patient’s skin and decrease pressure on the site that has been injured. Forearm ultrasound was done prior to radiography using SonoScape ultrasound machine with a linear array transducer 7.5 MHZ to 12 MHZ. Forearm radiograph was done as per the MTRH protocol. Continuous variables were summarized using mean and categorical variables were summarized in frequencies and percentages. Sensitivity and specificity were used for comparison. Results: Age of participants ranged from 0 to 17 years with a mean age of 9 years. The males accounted for 65.1%. On x-ray, fractures present were 60.2% with both the radius and ulna bones fractured at 56.0%, the radius bone alone was at 39.6% and ulna bone alone was at 4.4%. Distal third of the radius was the commonest fracture site with 39.2% on the left and 43.8% on the right. On ultrasonography, fractures diagnosed were 59.2% with both the radius and ulna bones fractured at 57.8%, radius alone was at 37.7% and ulna alone was at 4.5%. The distal radius was the most fractured at 38% on the left and 44.6% on the right. Positive and negative likelihood ratios were 11.56 and 0.08 respectively. The sensitivity and specificity of diagnosis of forearm fractures using ultrasound was 92.83% and 92% respectively at 95% confidence interval. There was a strong agreement between x-ray and ultrasonography with k=0.845 at P< 0.0001 which is considered as almost perfect agreement. Conclusion: Both radius and ulna bones are the commonest fractured bones with the right distal radius as the most common fractured site on both x-rays and ultrasonography. Ultrasonography can be used in place of plain x-rays in the diagnosis of forearm fractures due to its high sensitivity and specificity. Recommendation: It is recommended to clinicians and radiologists to use U/S instead of radiography in the diagnosis of suspected paediatric forearm fractures.