INTRODUCTION — This topic will review radial head subluxation (RHS). Elbow fractures and sports-related elbow injuries are discussed separately:
TERMINOLOGY AND MECHANISM OF INJURY — RHS (also called "nursemaid's elbow," "pulled elbow," and "annular ligament displacement") often results from axial traction on a pronated forearm with the elbow in extension. With sudden pulling on the distal radius, a portion of the annular ligament slips over the head of the radius and slides into the radiohumeral joint, where it becomes trapped (figure 1 and figure 2) . The symptoms of RHS are the result of displacement of the annular ligament. By the age of five years, the annular ligament has become thick and strong and is unlikely to tear or become displaced.
EPIDEMIOLOGY — RHS is a frequent elbow injury in young children, affecting approximately 20,000 children per year in the United States . RHS typically occurs between the ages of one and four years, with toddlers one to three years of age accounting for over 80 percent of cases [2,3], although cases have been reported in children younger than six months of age and as old as 11 years . Girls outnumber boys in most reports [2,3,5-9], and the left arm is more commonly injured [3,9,10].
Pulling on the arm, falls, and arm twisting are commonly reported mechanisms of injury [2,4]. Mechanisms of RHS such as "swinging" the child by the arms, lifting the child, or wrestling may more often involve male caregivers while RHS caused by pulling away, tripping, or getting dressed appears to be more associated with female caregivers .
History — The classic mechanism for RHS consists of a "pull injury" (figure 2) when a parent or caregiver grabs the arm to prevent the child from falling or pulling away. This history is present in approximately 40 to 50 percent of cases [2,4-6,11]. After the injury, the caregiver typically reports that the child is not using the affected arm. Anecdotally, the child may also complain of poorly localized wrist, arm, or elbow pain.
RHS also can occur when a child is swung by the forearms or during play. Other mechanisms include falling onto the elbow, minor direct trauma to the elbow, or a twisting motion of the arm . In addition, among infants younger than six months of age, the injury may occur when the infant rolls over in bed and traps the involved forearm under the body [4,12].
Physical examination — Examination should include inspection and palpation of the entire extremity, as well as the clavicle, on the affected side.
Children with RHS may hold the affected arm close to the body with the elbow either fully extended or slightly flexed and the forearm pronated (figure 3). The child is in little distress unless attempts are made to move the elbow. There may be mild tenderness over the anterolateral aspect of the radial head. However, the distal humerus and proximal ulna are usually nontender and not swollen. If the child reports wrist pain, there is no associated distal radial or ulna tenderness or swelling.
Passive range of motion of the elbow, if the child allows it, is normal. Pain with even mild supination of the forearm is almost always present.
RHS is not associated with neurovascular compromise, bony tenderness, deformity, or swelling. These findings suggest other diagnoses, primarily fracture. (See 'Differential diagnosis' below.)
Imaging — RHS is a clinical diagnosis, and radiologic investigation is usually unnecessary [3,13-15]. For patients with a typical history and physical examination as described above, plain radiographs should be avoided. Most children with suspected RHS who undergo radiography do not have a fracture. For example, in a multicenter, retrospective study of over 77,000 United States children diagnosed with RHS during more than 88,000 pediatric emergency department visits, radiographs were obtained in 29 percent of visits, but only 0.3 percent of patients had an upper extremity fracture . When performed, radiographs in children with RHS usually show normal anatomy . However, based upon case reports, displacement of the normal radiocapitellar line (image 1 and image 2) may occasionally be seen [17,18].
Although preliminary observational studies suggest that, when performed by trained and experienced ultrasonographers, point-of-care ultrasound may be useful in diagnosing RHS [19,20], point-of-care ultrasound is also unnecessary to diagnose RHS in most children.
In patients who do not have a history of a "pull injury" or who have equivocal physical examination findings, indications for plain radiographs include:
●<5 years of age:
•Age <6 months without a history of having the arm pulled or caught underneath the body when rolling over 
•A concerning mechanism of injury (eg, direct blow or high-force injury)
•A physical examination that demonstrates swelling beyond the anterolateral aspect of the radial head
•Focal bony tenderness over the proximal ulna or distal humerus
•Any bony deformity
•Inability to successfully reduce a presumed RHS (see 'Patients who fail initial reduction' below)
●≥5 years of age: Because RHS is uncommon at this age , most children with pain and immobility of the arm warrant radiographs unless there is a classic mechanism of an arm pull and a physical examination consistent with the diagnosis.
Nondisplaced (type I) supracondylar fractures are the most commonly reported fracture in young children undergoing imaging during evaluation for RHS [14,22] (see "Supracondylar humeral fractures in children", section on 'Definitive care'). In older children, radial head dislocation and lateral condyle fractures are less common but important diagnoses that may be missed. (See "Elbow anatomy and radiographic diagnosis of elbow fracture in children", section on 'Plain radiograph interpretation' and "Evaluation and management of condylar elbow fractures in children", section on 'Lateral condylar fracture'.)
DIAGNOSIS — The diagnosis of RHS can be made when the characteristic history (ie, pulling on the arm) and examination findings (figure 2 and figure 3) are present in a child younger than five years of age. The clinician should also ensure no focal bony tenderness, bruising, deformity, or swelling suggestive of a fracture, especially over the distal humerus and proximal ulna.
Plain radiographs are rarely indicated (see 'Imaging' above). If performed, plain radiographs should show no signs of fracture or dislocation. A thorough physical examination is critical before ordering radiologic imaging because positioning of the elbow to obtain radiographs may lead to reduction of the RHS. In equivocal cases, when the child has full range of motion of the arm without pain after radiographs are obtained, the diagnosis of RHS is confirmed.
Even in the absence of the classic history, the diagnosis is likely when the examination is characteristic in younger children. However, the clinician should be wary of making the diagnosis of RHS in children older than five years and consider a broader differential diagnosis.
DIFFERENTIAL DIAGNOSIS — In children younger than five years of age with suspected RHS, fracture near the elbow represents the most important diagnosis to exclude. Most fractures of the upper extremity in young children arise from falls on to an outstretched arm; pulling of the arm is an unusual fracture mechanism. Children with fractures typically have swelling, bony tenderness, or deformity on physical examination; all of these findings are usually absent in children with RHS. Plain radiographs of the affected region often demonstrate the fracture. However, children with Salter-Harris I physeal fractures may have normal radiographs that require repeat imaging in seven days to diagnose. These patients will have point tenderness over the physis at initial evaluation. (See "General principles of fracture management: Fracture patterns and description in children", section on 'Physeal (growth plate)' and "General principles of fracture management: Fracture patterns and description in children", section on 'Salter I (Ogden IA-C)'.)
RHS is an uncommon cause of anterolateral elbow pain and limitation of motion in children older than five years of age. Such patients typically warrant radiographs after an acute injury to evaluate for fracture or dislocation and prior to attempts at reduction. In older patients with a more subacute presentation or those who lack a specific history of injury, plain radiographs may demonstrate osteochondrosis of the capitellum (Panner disease) or osteochondritis dissecans. The differential diagnosis of older active children with anterior or lateral elbow pain is discussed separately. (See "Elbow injuries in active children or skeletally immature adolescents: Approach", section on 'Anterior elbow pain' and "Elbow injuries in active children or skeletally immature adolescents: Approach", section on 'Lateral elbow pain'.)
Radial head subluxation — Children with typical features of RHS and no findings of other injury on history and physical examination should undergo reduction without imaging (algorithm 1) (see 'Imaging' above). Reduction is easily learned and can be performed in the ambulatory setting (office, urgent care center, or emergency department) .
●Procedure – Reduction of RHS is brief but results in additional patient discomfort and crying. It is therefore important to explain the procedure to the caretakers before attempting reduction. The procedure is best performed with the child seated comfortably in the parent's arms and the examiner seated and facing the child. Given the rapid resolution of symptoms with successful reduction of RHS, sedation and pain medications are not usually needed.
●Reduction technique – We suggest that children with RHS undergo reduction by the hyperpronation method rather than the supination/flexion method. The examiner supports the child's arm at the elbow and places moderate pressure with a finger on the radial head. The examiner grips the child's distal forearm with the other hand and hyperpronates the forearm (figure 4) . A click may be felt by the finger over the radial head when the displacement is reduced.
Although hyperpronation is associated with a higher rate of successful RHS reduction as discussed below, the supination/flexion method is still widely taught and is a reasonable alternative if the clinician prefers. The examiner supports the child's arm at the elbow and exerts moderate pressure on the radial head with one finger. With the other hand, the examiner holds the child's distal forearm and then pulls with gentle traction. While maintaining traction, the examiner fully supinates the child's forearm and then fully flexes the elbow in one smooth motion (figure 5). A click may be felt by the finger over the radial head or a pop may be heard by the examiner when the displacement is reduced .
With successful reduction, the child experiences significant pain relief and fully recovers range of motion of the arm (including the ability to reach over the head) within 15 to 20 minutes. Some children are initially reluctant to use the arm, but do so readily once they realize that it is no longer painful. Younger children may be coaxed to reach for a rattle, toy, or car keys as a way to indicate successful reduction.
Our preference for the hyperpronation method rather than the supination/flexion method is supported by several clinical trials, most of which had important limitations such as lack of blinding, small sample size, and selection bias [23-28]. The available data suggest that hyperpronation is more likely to be successful on the first or second attempt and is perhaps less painful.
In a meta-analysis of eight randomized and quasi-randomized trials comparing the two techniques in 811 children, the hyperpronation method more often successfully reduced RHS on the first attempt (91 versus 74 percent; risk ratio [RR] 2.86 [95% CI 2-4]) and after up to two attempts (97 versus 80 percent; risk ratio 6.2 [95% CI 3-11]) . Similar findings were noted in another trial published after the meta-analysis .
Both procedures can be painful, and it is unclear whether one is less painful than the other. Some trials have reported less pain with the hyperpronation technique, though the finding wasn't consistent across different assessors (parents, nurses, physicians) [25,26]. Other trials failed to detect important differences in pain ratings between the two techniques [27,28]. The findings regarding pain could not be pooled in the meta-analysis because each trial used a different pain scale .
Recurrent radial head subluxation — RHS may recur when the child sustains another injury with the typical mechanism (see 'Terminology and mechanism of injury' above). Recurrence rates range from 27 to 39 percent [5-8,29]. Recurrent RHS is reduced as described above (algorithm 1). In one small trial of 64 children with recurrent RHS, a long arm cast reduced the risk of acute recurrence compared with no immobilization (0 versus 13 percent, respectively) . However, the rate of acute recurrence in this study was high compared with larger observational studies. Although casting may rarely be appropriate for individual children with multiple episodes of recurrent RHS, we do not routinely cast children or refer them for orthopedic evaluation unless recurrence is frequent enough to significantly limit the child's physical activities. (See 'Radial head subluxation' above.)
After reduction of an easily reduced recurrent RHS, capable caregivers who are comfortable with learning the procedure can be taught the hyperpronation maneuver to permit home management of any future recurrences. However, the clinician should have confidence that the caregiver can reliably exclude signs of fracture before providing this instruction and have the parent demonstrate the technique before discharge.
Because of strengthening of the annular ligament, the injury rarely recurs after four to five years of age .
Patients who fail initial reduction — Approximately 4 percent of patients with clinical findings of RHS will fail reduction at the initial attempt [4,23]. If the initial reduction is not successful (ie, the patient is not moving the arm after a period of observation of up to 20 minutes), then the clinician should re-evaluate for subtle signs of fracture such as point tenderness at the distal posterior humerus. If no signs of fracture are present, then reduction can be repeated up to two times (algorithm 1). Although either method may be used for repeat reduction, the success rate with repeat reduction appears to be higher using the hyperpronation method .
If the arm still remains immobile after two or three reduction attempts, then plain radiographs of the elbow are warranted to evaluate for a fracture. Patients with fractures on imaging should receive appropriate immobilization and orthopedic consultation or referral as dictated by the degree of displacement and the specific type of fracture. (See "Supracondylar humeral fractures in children" and "Proximal fractures of the forearm in children" and "Evaluation and management of condylar elbow fractures in children" and "Epicondylar and transphyseal elbow fractures in children".)
Patients who fail initial reduction and have normal plain radiographs of the elbow should have the arm placed in a sling. These patients often have a persistent RHS in which the radial annular ligament is too swollen to be reduced. Anecdotally, patients who are younger and have had a longer duration of arm immobility prior to seeking medical care may be at increased risk. Additional symptomatic treatment includes ibuprofen or other nonsteroidal antiinflammatory medication (if there is no allergy or other contraindication to their use) and local application of ice packs, if tolerated, to reduce local swelling. Limited evidence suggests that these patients often will have normal arm movement at follow-up . No long-term sequelae have been reported from unrecognized or unreduced RHS .
INDICATIONS FOR SPECIALTY CONSULTATION OR REFERRAL — Children with RHS that is successfully reduced do not need orthopedic consultation or referral.
Patients with fractures discovered during the evaluation for RHS warrant orthopedic involvement as dictated by the degree of displacement and the specific type of fracture.
For children with a persistently immobile arm after reduction attempts and normal radiographs, follow-up with a primary care provider or orthopedic surgeon should occur if there is no improvement in arm range of motion within two to three days.
DISPOSITION AND FOLLOW-UP — After successful reduction of a RHS, no additional treatment, immobilization, activity restriction, or follow-up is necessary. The caregiver should receive instructions on how to avoid recurrence (ie, avoid sudden pulling on the arms, picking the child up by the hands or wrists, and forcefully removing coats and shirts). (See 'Information for patients' below.)
Patients who fail reduction and are identified with a fracture on plain radiographs should receive appropriate immobilization and orthopedic consultation or referral as dictated by the degree of displacement and the specific type of fracture. Nondisplaced (type I) supracondylar fractures are the most frequently described fracture in patients initially misdiagnosed with RHS [14,22]; the management of these injuries is provided separately. (See "Supracondylar humeral fractures in children", section on 'Definitive care'.)
Patients who fail reduction and have normal plain radiographs of the elbow should receive the previously described supportive care (see 'Patients who fail initial reduction' above) and undergo follow-up in two to three days to assess arm movement. This follow-up may be with the primary care provider or with an orthopedic surgeon with pediatric expertise. Further care is determined by the examination at follow-up:
●Patients with full arm mobility can be presumed to have had a RHS that spontaneously reduced and require no further care. Parents should receive anticipatory guidance on prevention of repeat RHS as described above.
●Patients who have persistent immobility of the arm warrant splinting (figure 6) (see "Basic techniques for splinting of musculoskeletal injuries", section on 'Long arm splint') and orthopedic referral if initial follow-up is with the primary care provider.
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Pulled elbow (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Mechanism of injury – Radial head subluxation (RHS; also called "nursemaid's elbow," "pulled elbow," and "annular ligament displacement) often results from axial traction on a pronated forearm with the elbow in extension. With sudden pulling on the distal radius, a portion of the annular ligament slips over the head of the radius and slides into the radiohumeral joint, where it becomes trapped (figure 1 and figure 2). (See 'Terminology and mechanism of injury' above.)
●Evaluation and diagnosis – The diagnosis of RHS can be made when the characteristic history (ie, pulling on the arm) and examination findings (figure 3) are present in a child younger than five years of age. The clinician should also ensure no focal bony tenderness, bruising, deformity, or swelling suggestive of a fracture prior to reduction. Radiologic investigation is usually unnecessary. (See 'Evaluation' above and 'Diagnosis' above.)
●Imaging – The approach to imaging depends upon the age of the child (see 'Imaging' above):
•<5 years of age – In children <5 years old, RHS is a clinical diagnosis, and radiologic investigation is usually unnecessary. Plain radiographs of the elbow may be appropriate in selected patients to exclude fractures or dislocation if one or more of the following are present:
-Concerning mechanism of injury (eg, direct blow or high-force injury).
-No mechanism of injury in an infant <6 months of age.
-Physical examination demonstrates focal bony tenderness, swelling, or deformity of the arm or clavicle beyond that localized to the radial annular ligament.
-Inability to successfully reduce a presumed RHS despite two to three attempts.
•≥5 years of age – RHS is an uncommon cause of anterolateral elbow pain and limitation of motion in these patients. Unless there is a classic mechanism of an arm pull and clear findings of RHS on physical examination, such patients typically warrant plain radiographs of the elbow prior to attempts at reduction. (See 'Imaging' above and 'Differential diagnosis' above.)
Nondisplaced (type I) supracondylar fractures are the most commonly reported fracture in children undergoing imaging during evaluation for RHS. (See 'Imaging' above.)
●Reduction technique – For most children with RHS, we suggest reduction by the hyperpronation method (figure 4) rather than the supination/flexion method (figure 5) (Grade 2C). The hyperpronation method has a higher first-attempt success rate. However, the supination/flexion technique (figure 5) is a reasonable alternative if the clinician is more skilled with this technique. Successful reduction results in prompt pain relief and a full range of motion of the affected arm within 15 to 20 minutes. (See 'Radial head subluxation' above.)
●Management – For children with the characteristic clinical findings of RHS, including children with recurrent injury, initial management consists of attempts at reduction as provided in the algorithm (algorithm 1). Further care is determined by the results of reduction attempts:
•Successful reduction – After successful reduction of a RHS, no additional treatment, immobilization, activity restriction, or follow-up is necessary. The caregiver should receive instructions on how to avoid recurrence (ie, avoid sudden pulling on the arms, picking the child up by the hands or wrists, and forcefully removing coats and shirts).
-Fracture on imaging – Patients with fractures discovered during the evaluation for RHS warrant orthopedic involvement as dictated by the degree of displacement and the specific type of fracture. (See 'Differential diagnosis' above and 'Indications for specialty consultation or referral' above.)
-No fracture on imaging – Patients who fail reduction and have normal plain radiographs of the elbow should be placed in a sling and discharged with additional symptomatic treatment including ibuprofen or other nonsteroidal antiinflammatory medication (if no allergy or other contraindication to their use) and local application of cold therapy, if tolerated, to reduce local swelling.
Although most of these patients will improve with symptomatic treatment, follow-up with a primary care provider or orthopedic surgeon should occur if there is no improvement within two to three days. (See 'Indications for specialty consultation or referral' above and 'Patients who fail initial reduction' above.)
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