The present study introduced the application of ultrasound-guided closed reduction in distal radius physeal fracture management. Given the anatomical features of the physeal cartilage, ultrasound is particularly suitable for this purpose due to its ability to display direct signs of physeal fracture more effectively than radiography. With the real-time guidance of the ultrasound, we were able to achieve an anatomic or nearly anatomic reduction in this study. Furthermore, ultrasound-guided closed reduction can be performed in the emergency room or the outpatient clinic rapidly and easily where fluoroscopy is unavailable in these departments of most hospitals in China.

Although previous studies have provided support for the use of ultrasound in the treatment of paediatric forearm fractures [8, 10, 21], there is limited evidence demonstrating the reduction of physeal fractures under ultrasound guidance. This study presents a novel technique for ultrasound-guided closed reduction of distal radial physeal fractures, with an initial anatomic reduction success rate of 84.3%. This is comparable to those reported in previous studies [4]. Besides, our study performed blind closed reduction without sedation. It is postulated that the successful anatomic reduction rate was increased under sedation. Furthermore, our findings indicated good agreement between ultrasound and radiography assessments post-reduction, with ultrasound confirming anatomical reduction success at a sensitivity of 95.3% and specificity of 87.5%. The use of ultrasound in multiple planes provides sufficient visualization information to determine the status of fracture reduction. However, the role of ultrasound in improving fracture reduction success remains uncertain. Nevertheless, our results support the utility of ultrasound as a tool for assessing adequate reduction of distal radial physeal fractures.

Ossification of the distal radius epiphysis typically begins between 8 and 18 months, with complete closure at the approximate age of 17 years [22]. Ultrasound is advantageous for detecting epiphyseal cartilage, although its application in diagnosing distal radial fractures in children primarily focuses on the metaphysis [23, 24]. The diagnosis of periarticular epiphyseal fracture by ultrasound is rare [11, 12], but ultrasound has been utilized for diagnosing other types of epiphyseal fractures such as distal humeral epiphyseal fracture [25], lateral humeral condyle fracture [26], and radial neck fracture [14]. Additionally, Chen[10]reports three cases of Salter-Harris type I injury of distal radius epiphyseal fracture diagnosed by ultrasound. Snelling [27] suggests using the"Point-of-care ultrasound (POCUS) 1-cm rule"to aid in diagnosing Salter-Harris type II distal radius fractures. Our study directly shows that epiphyseal cortical impedance appears high and reveals a hyperechoic image on ultrasound, whereas epiphyseal cartilage exhibits low impedance and reveals a hypoechoic image on ultrasound. High-quality ultrasound images can be obtained to diagnose displacement between hypoechoic epiphyseal cartilage and hyperechoic cortex in cases of distal radius epiphyseals fractures. Therefore, ultrasound could be used for diagnosing these fractures. The ability of ultrasound to assess the physeal cartilage is better than radiography.

The current study showed that closed reduction under ultrasound guidance can achieve near-anatomical and anatomical reduction. The potential for bone remodeling after residual angulation of distal radius epiphysis injury and its impact on function is controversial. Regardless of the great potential for remodeling at the physis, displaced physeal fracture may not allow for complete correction of displacement and angulation [2]. Previous studies have shown that approximately 80% of epiphyseal injuries occur at ages older than 10 years [18, 28]. Larsen [2] considers that children over 10 years old may not be able to obtain completely remodeled angular deformity. Achieving anatomical reduction is valuable in children with little remaining growth potential and a high risk of residual angulation. Moreover, non-anatomic reduction may increase the risk of redisplacement [4]. It could be essential to undergo repeated reduction to achieve anatomical realignment. However, multiple reduction attempts may elevate the risk of growth arrest [28], highlighting the significant benefit our study provides by assisting physicians in determining when a closed reduction procedure is complete. After each reduction attempt, ultrasonography can be effective in assessing the quality of the reduction. Several studies support these results of a decrease in the number of reduction attempts in distal radial fracture [29, 30]. Therefore, our study suggests that ultrasound guidance can accurately facilitate the process of reducing epiphyseal fractures, and avoid invalid reattempts.

Portable fluoroscopy may be utilized for guidance and assessment of reduction before casting, however, its availability is limited in some emergency departments. Radiographs are commonly employed to confirm the effectiveness of fracture reduction in most hospitals, but this process is time-consuming and not available in real-time. Ultrasound serves as a readily easily acquired, easy-to-use, and economical alternative that has been widely utilized as a diagnostic tool and an aid in emergency room settings. It is very noteworthy that ultrasound can rapidly and accurately visualize fracture reduction in a resource-limited setting lacking fluoroscopy and sedation. Similar to previous studies [8, 9, 21], ultrasound assists in reducing the need for further radiography and shortening hospital stays. Furthermore, adhering to the ALARA (“as low as reasonably achievable”) radiation safety principle emphasizes the use of ultrasound guidance over fluoroscopy [31]. Ultrasound-guided CR of fracture is ideally suited for applications in outpatient or emergency room settings without radiation exposure.

Our study has some limitations. First, a brief yet essential learning phase is required for this technique. Before the examination, the operator underwent accredited training on the basic ultrasonic structure of the distal radius physeal fracture. However, physicians without any prior experience in ultrasound and limited training can still accurately diagnose pediatric distal radial fractures [32]. Additionally, assessment of the contralateral side's ultrasonic structure is crucial for accurately evaluating epiphyseal injuries. Secondly, the study involved a relatively small sample size and utilized a retrospective design. Without a control group, there is no data available on the advantages of ultrasound-guided reduction compared to fluoroscopy or postreduction radiography. An ideal study would be prospective to compare ultrasound with other techniques to address whether ultrasound-guided reduction offers superior results. Nevertheless, based on these findings, we believe that our technique is effective and safe when compared to other techniques [18, 28, 33,34,35]. Thirdly, while ultrasound imaging shows good alignment and may even replace postreduction radiography in some cases, it cannot detect issues after cast application; therefore radiography remains superior during follow-up.