One of the more common reasons for an orthopaedic consultation in the newborn nursery is for an infant who does not move an arm. The diagnoses that come quickly to mind are brachial plexus injury or fracture. However, infection is the most important diagnosis to make, as it can usually be treated successfully if recognized early, but may lead to permanent disability if the diagnosis is delayed (Fig. 12-1).

A newborn with a painful limb will demonstrate pseudoparalysis and not move the limb voluntarily. To the inexperienced, this may be misinterpreted as a true paralysis or brachial plexus injury. One approach to help differentiate pseudoparalysis from paralysis is to shake the arm; if you are being observed, perhaps explain what you are doing so you do not look like a calloused orthopod. If the child reacts to movement with pain, the diagnosis is likely fracture or infection. If there is no sign of pain, the diagnosis is likely neurologic injury. A potential pitfall of this approach is that an infant may have a fracture or infection and a brachial plexus injury, so a neurologic examination is essential even in the case of a known fracture or infection. One series reported that nearly 10% of newborns with a clavicle fracture also had a brachial plexus palsy.¹

When dealing with the clinical diagnosis of infections in newborns, we enter into a different universe. In the first week of life, normal white blood cell count ranges between 9000 and 30,000 cells/mL. A total white cell count below 5000 cell/mL is generally considered to be suggestive of severe infection, although some overlap between infected and noninfected neonates occurs. Although over half of neonates with sepsis present with fever, hypothermia may be the leading sign of infection in 15% to 20% of infected neonates.

The diagnosis of osteoarticular infection may be suspected on clinical examination by a limb that appears painful when moved. In the absence of an obvious fracture on radiographs, an ultrasound should be performed which may demonstrate a septic shoulder or subperiosteal collection. Significant intra-articular pus may cause subluxation or dislocation of the joint (Fig. 12-2). A septic shoulder requires urgent surgical drainage if the newborn’s condition permits. Adjacent osteomyelitis should be expected, as vessels cross the physis at this age. Of course, many of the principals here apply to the lower extremities as well. In particular, if there is a septic hip, the other hip should be closely investigated with ultrasound and/or aspiration (Fig. 12-3).

Most osteoarticular infections in this age group will be due to Staphylococcus aureus. That being said, given the high-risk nature of this population, Group B Streptococcus, Escherichia coli, Kingella kingae, Candida species, and other pathogens are seen much more commonly here than in older children. Obtaining cultures to help direct therapy is critical in successfully treating these infections (Fig. 12-4). There are some odd infections in the newborn, such as calcaneal osteomyelitis following a heel stick.²

There are many degrees of injury to the brachial plexus. In the most common type with upper plexus involvement, or Erb palsy, the characteristic appearance of waiter’s tip—shoulder internal rotation, elbow extension, forearm pronation, and wrist flexion (Fig. 12-5)—aids in diagnosis. The surgeon should be aware that the phrenic nerve may be involved as well as a Horner syndrome (ptosis, miosis, and enophthalmos). Physical therapy should be started to maintain motion, as muscle imbalance may rapidly lead to contracture and joint incongruence.

The big pitfall in fractures is a physeal fracture of the proximal humerus, or less commonly the distal humerus (Fig. 12-6). The humeral head and capitellum are not yet ossified, so the fracture is not easily appreciated on plain radiographs. On examination, there should be fullness, tenderness, and often warmth, similar to an infection. An ultrasound demonstrates the fracture. So the following clinical algorithm will help one make the diagnosis: arm hurts with movement, get a radiograph or ultrasound, depending on what is best at your institution. A radiograph will not show infection or some physeal fractures, so if the radiograph is negative, one must get an ultrasound. An ultrasound in the hands of an experienced user is probably the best study.³

Other fractures of the upper extremity and clavicle are more easily diagnosed on plain radiographs. Healing is very rapid, and outcome is benign with extensive remodeling the rule.⁴ In the newborn, immobilization in generally needed for only 7 to 10 days (Fig. 12-8). For children with multiple fractures think about osteogenesis imperfecta, neonatal rickets, or neuromuscular disorders. Femur fractures in newborns are commonly treated in newborns with a Pavlik harness.