Transphyseal separations of the distal part of the femur are infrequently seen in newborns. These fractures are often caused by birth injuries (e.g., during breech deliveries)1,2. There is swelling in the affected extremity and pain with palpation, and the transphyseal separation can be confused with a septic joint. Patients must be imaged appropriately with use of radiographs and magnetic resonance imaging (MRI) to detect more subtle fractures2. When the diagnosis of distal femoral physeal separation has been made, treatment choices include closed reduction only, closed reduction and percutaneous pinning, or open reduction and percutaneous pinning. Previous case reports have described percutaneous pinning as the preferred method of treatment in neonates3,4. However, this case report describes a transphyseal fracture of the distal part of the femur diagnosed at seven days of age in a neonate; the fracture was repositioned at the bedside without administering general anesthesia, and it was adequately treated in a long leg splint. The two-year follow-up demonstrated complete remodeling and no clinical sequelae from the injury. The patient's parents were informed that data concerning the case would be submitted for publication, and they provided consent.
A 1.53-kg twin infant was born at thirty-four weeks to a forty-two-year-old G1 P1 woman. The infant was spontaneously vaginally delivered and was born in a footling breech position. While the infant was in the neonatal intensive care unit (NICU) for seven days receiving a gastrointestinal workup for abdominal distention and bilious aspiration, it was noted that there was swelling superior to the left knee and that he would cry when the knee was palpated. These finding were concerning for a septic joint, and an orthopaedic consultation was obtained.
The patient had no noteworthy medical history, but the mother had a history of herpes simplex virus without active lesions during pregnancy. The infant was treated prophylactically with acyclovir. The infant had no history of prior surgery and had no known drug allergies. There was a family history of spina bifida, hypertension, diabetes, and breast and skin cancer.
On physical examination, the infant was afebrile and in no acute distress. The left knee was in valgus and flexed. The distal part of the femur was tender to palpation, and there was decreased knee motion. There was no knee effusion and no erythema. The infant's left hip had negative Barlow and Ortolani signs, and there was full hip motion without pain. He had a positive Babinski sign, a startle reflex, and palpable dorsalis pedis pulses.
Laboratory markers for inflammation, including white blood-cell count (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) level, as well as blood cultures, were normal. However, it is important to note that septic neonates may have negative inflammatory markers. A vascular ultrasound of the left leg prior to the orthopaedic consultation was negative for deep vein thrombosis, and a dedicated ultrasound of the hip demonstrated no effusion and no hip dysplasia. Radiographs of the left leg (Figs. 1-A and 1-B) were suspicious for a physeal injury of the distal part of the femur because the ossified femur was not in alignment with the ossified tibia on the anteroposterior view. The leg was placed in a long leg splint, and a noncontrast MRI (parameters: TR/TE, 2020/110.96 msec; matrix size, 256 × 256; slice thickness, 2 mm; interslice gap, 2.5 mm) of the left knee was obtained. The MRI demonstrated a Salter-Harris II fracture of the distal part of the femur (Figs. 2-A and 2-B). The existing splint was then removed, and the patient's leg was gently repositioned in a splint that extended to the gluteal area and provided stability to the distal part of the femur. Intravenous pain medication (morphine, 0.03 mg) was administered without general anesthesia or conscious sedation. Following repositioning, radiographs (Fig. 3) demonstrated acceptable leg alignment. (The chief concern was not the alignment of the fracture but avoiding damage to the distal femoral physis.) The patient was more comfortable after this procedure and was discharged from the NICU and the hospital without any additional complications.
The patient returned for regular follow-up examinations that demonstrated eventual remodeling of the femur. At three weeks after injury, there was partial healing of the femoral transphyseal fracture (Figs. 4-A and 4-B), and at twenty-four months, there was complete remodeling of the femur (Figs. 5-A and 5-B). There was no limb-length discrepancy, and there were no residual functional limitations; the patient had normal developmental milestones.
To the best of our knowledge, nonoperative treatment of transphyseal separation of the distal part of the femur in neonates has not been well described. There are multiple studies describing pediatric distal femoral physeal injuries5-11, which are commonly known as Salter-Harris II fractures, but it is a rare condition in neonates. The secondary center of ossification of the distal part of the femur develops on average at thirty-six weeks of gestation and is usually present at forty weeks (at term). Infants who present in the breech position are most susceptible to experiencing a transphyseal separation of the femur; one study reported that one of thirty-five birth injuries occurred in the distal part of the femur1. There are a variety of methods of treatment for these fractures, including closed reduction and immobilization, closed reduction and percutaneous pinning, or open reduction and percutaneous pinning. In older children, closed reduction with percutaneous pinning is the first option of treatment for Salter-Harris I and II fractures of the distal part of the femur12, but fixation may fail and open reduction and internal fixation may be required13. However, in neonates, authors of case reports have advocated the use of closed or open reduction with percutaneous pinning3,4. While the outcomes were satisfactory, we present our case as an alternative to operative fixation with a similar clinical outcome.
This case demonstrates that closed reduction and long leg splinting can provide adequate treatment of distal femoral transphyseal fractures in newborns, reduce damage to the distal femoral physis, and provide comfort to the patient. Of note, since the injury was already seven days old and starting to heal, it was more stable than most displaced physeal fractures, which lowered the risk of additional displacement. This case also shows that nonoperative management of a distal femoral transphyseal fracture with only intravenous pain medication can be beneficial in neonates in order to prevent the use of general anesthesia and to prevent the patient from having to leave the NICU. Staying within the NICU is especially important for patients who have other medical comorbidities or are medically unstable.
When working up a patient with unilateral lower-extremity swelling, early detection and diagnosis are paramount. One differential diagnosis that should not be missed is the presence of a septic joint, which also presents with unilateral swelling and tenderness to palpation. Laboratory tests for inflammatory markers, including WBC, ESR, and CRP levels, must be measured, but they may be confounded by other medical comorbidities. Additionally, these laboratory markers may remain normal in septic neonates. In terms of imaging, the absence of a secondary center of ossification, especially at thirty-four weeks of gestation, can make radiographs difficult to interpret. After radiographs, advanced imaging is recommended, including ultrasound to detect fluid or hip dysplasia and MRI to image fractures or fluid collections. A knee arthrogram is another method that may be used to detect physeal displacement. When diagnosis is delayed, the patient may have subsequent malalignment and limb-length discrepancy, as was reported in one case where an obstetric lesion was undiagnosed for seven weeks14. Once a distal femoral transphyseal fracture is diagnosed, closed reduction should first be attempted with use of intravenous pain medication. Because these neonates are so small, placing a long leg cast on the affected extremity may be difficult; use of a long leg splint may be more beneficial for immobilization. However, either treatment modality is acceptable. In our patient, there was callus formation and no tenderness to palpation at the fracture site at three weeks. The splint was removed and the bone remodeled well.
Our case report demonstrates the treatment of a neonatal distal femoral transphyseal fracture with splint immobilization; the splint was applied with the use of intravenous analgesia. Alignment of the distal part of the femur and growth from the distal femoral physis were normal two years following the injury and treatment. In infants, nonoperative treatment is preferable because there is minimal trauma to the distal femoral physis, no conscious sedation is needed, and patients do not need to be transported to the operating room. Additional follow-up is necessary to ensure that there is no physeal abnormality with growth.
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Disclosure: None of the authors received payments or services, either directly or indirectly (i.e., via his or her institution), from a third party in support of any aspect of this work. One or more of the authors, or his or her institution, has had a financial relationship, in the thirty-six months prior to submission of this work, with an entity in the biomedical arena that could be perceived to influence or have the potential to influence what is written in this work. No author has had any other relationships, or has engaged in any other activities, that could be perceived to influence or have the potential to influence what is written in this work. The complete Disclosures of Potential Conflicts of Interest submitted by authors are always provided with the online version of the article.