Case Reports Scintigraphy of Toddler's Fracture

John H. Miller and Ronald A. Sanderson Childrens Hospital of Los Angeles and University of Southern California, School of Medicine, Los Angeles, California Under ordinary circumstances a toddler's fracture of the lower extremity is diagnosed by clinical evaluation and history. Often the initial conventional radiograph is unrevealing, but the fracture is diagnosed and treated based on appropriate clinical and laboratory findings. In rare instances, a patient with an unsuspected toddler's fracture may present with an atypical history, unusual physical findings, or laboratory values suggesting the presence of an inflammatory process. Skeletal scintigraphy in this small group of patients has been valuable in defining a spiral fracture of the midshaft of the tibia connected with a toddler's fracture. We report the scintigraphic appearance from the findings in six patients with unsuspected toddler's fracture evaluated by this method.

J NucíMed 29:2001-2003,1988

A,. toddler's fracture is an injury to the lower extrem systemic signs secondary to common childhood viral ity, usually seen between 1 and 3 yr of age. It is caused illnesses, such as an acute upper respiratory infection, by a twisting or torsional injury to the lower extremity can add to the difficulty in differentiating an early resulting in a spiral fracture of the midshaft of the tibia. osteomyelitis from a toddler's fracture. The radio- Often the injury is unwitnessed by a parent and is nuclide bone scan will be helpful in establishing the sustained by a fall or by entrapment of the foot as the correct diagnosis in this injury and its appropriate treat patient rolls around. The usual clinical presentation is ment. a child who refuses to walk or to bear weight on the involved limb; there may be pain or irritability related MATERIALS AND METHODS to movement of the involved lower extremity. The Six children, four males and two females, age 15 to 38 mo, clinical signs are a refusal to walk, an antalgic limp, who were subsequently proven to have toddler's fractures were swelling, warmth, local tenderness, or minimal signs initially evaluated clinically and by conventional radiography and/or symptoms. and skeletal scintigraphy. Conventional AP and lateral radiog The conventional radiographie findings vary from a raphy of the involved extremity was performed in all patients fine, spiral microfracture to an obvious, mildly dis at the time of initial presentation. Scintigraphic evaluation placed, long spiral fracture of the midshaft of the tibia. was performed at this time as well, which was between 1 and The most subtle fractures may not be visible on plain 3 days from the initial onset of symptoms. Follow-up radiog films, including oblique views. Treatment of this injury raphy was performed at 7 to 10 days on three patients and at requires the application of a long leg cast to be worn the termination of casting treatment in all patients. Double or for~6wk(7,2). triple phase skeletal scintigraphy was performed in all patients following intravenous administration of 0.280 mCi/kg (mini The diagnostic dilemma caused by this fracture is mum dose 2.0 mCi) of technetium-99m méthylènediphos- that the injury the child sustains is quite often not phonate ([9<)mTc]MDP). Dynamic scintigraphy at 3-sec inter witnessed by the parent, and the child is irritable or vals was performed of both lower extremities. Immediate, refuses to walk relative to the pain experienced in the static, blood-pool scintiphotos were then obtained to assess patient's involved lower extremity. The occurrence of the tissue phase of tracer activity. Delayed static 300,000- an unrevealing initial conventional radiographie ex 500,000 count scintiphotos of the entire lower half of the body amination may add to the diagnostic difficulty. Differ were obtained. Lateral and/or oblique scintiphotos were then ential diagnoses must include osteomyelitis of the prox obtained to best demonstrate abnormalities involving the tibia imal or distal tibia or fibula. A child with fever or in these patients.

Received Dec. 22, 1987; revision accepted July 11, 1988. RESULTS For reprints contact: John H. Miller. MD, Div. of Nuclear Radiology, Childrens Hospital of Los Angeles, 4650 Sunset Blvd., In no patient in this series was there history of a fall Los Angeles, CA 90027. or an injury. Moreover, there were signs, such as fever

Volume 29 •Number 12 •December 1988 2001 FIGURE 1 Anteroposterior (A) and lateral (B) radiographs of the right tibia are unremarkable. The anterior immediate post injection scintiphoto revealed slightly increased uptake in the mid shaft of the right tibia. Anterior (C) and lateral (D) ["Te] MDP scintiphotos of the lower extremities reveal increased activity in the midshaft of the right tibia. On the lateral scintiphoto (D), the abnormal osteoblastic activity is seen to course from posterior to anterior (arrowheads), indicating the presence of a spiral-type fracture. These scintiphotos were obtained on the same day as the initial radiographs. Anteroposterior (E)and lateral (F)radiographs obtained ~6 wk after the initial radiographs reveal the presence of considerable periosteal bone in the midshaft of the right tibia, confirming the presence of a spiral fracture of the midshaft.

2002 Miller and Sanderson The Journal of Nuclear Medicine or increased white blood cell count, or symptoms such 4). We perform scintigraphy of the lower half of the as refusal to bear weight on either limb which precluded body in every patient evaluated for limp, leg pain, the correct clinical diagnosis of toddler's fracture. Initial refusal to walk or bear weight, as referral of pain to the radiographie evaluation of these patients revealed no leg from discitis or sacro-iliac pyarthrosis commonly abnormality of the tibia. occurs (3-5). For this reason, immediate post-injection In three patients, radiographs obtained between 7 blood-pool scintiphotos are obtained of the lumbar and 10 days following initial casting revealed spiral- spine, pelvis, hips, and complete lower extremities, type fractures of the midshaft of the tibia. In all patients which in approximately one-half of patients with a following 6 wk of immobilization, periostea! new bone toddler's fracture will reveal increased tissue phase ac compatible with a healed spiral-type or torsion-type tivity. This represents a local hyperemic response to the fracture was identified. In this group of patients, no subclinical disruption of the periostium (3). Patients other lesion was identified on either radiographie or with a toddler's fracture of the tibia reveal a typical skeletal scintigraphic examination of the lower half of scintigraphic appearance, abnormal osteoblastic activ the body. ity which courses in an oblique manner across the All patients were evaluated by two-phase skeletal midshaft of the involved tibia (Fig. 1). This typical scintigraphy and three patients had three-phase exami distribution allows differentiation from metaphyseal or nations. No abnormality was seen on dynamic scintig juxta-articular increased activity seen in osteomyelitis raphy in these patients. On the blood-pool scintiphotos or inflammatory joint disease. We perform over 450 in three patients there was slightly increased tracer pediatrie isotope skeletal examinations per year, and no activity along the shaft of the involved tibia. In all six other osseous lesion has osteoblastic activity in this patients on the delayed scintiphotos, abnormal uptake spiral or oblique appearance. In patients with a typical of [99mTc]MDPinvolving the tibial shaft at the site of scintigraphic appearance of a toddler's fracture, casting clinical symptomatology was identified. This abnormal can be continued for 6 wk without the need for repeat uptake was seen in the midshaft of the tibia in all radiography and recasting at 7 to 10 days following patients, and an apparent oblique course was seen in initiation of treatment. However, the conventional three. There was no evidence of abnormal uptake of approach of initial casting following the re- tracer in either the metaphyseal regions or the juxta- evaluation at 7 to 10 days should be utilized in those articular or articular regions of any of the involved patients with the clinical symptomatology of toddler's extremities. No positive blood cultures were obtained, fracture and an unremarkable radiographie examina and no patient in this series received any antibiotic tion. therapy. Skeletal scintigraphy provides an excellent means to evaluate the lower half of the body in a child who presents with a limp, an atypical history or clinical DISCUSSION presentation, and signs of systemic illness with a nega Toddler's fracture should be considered when a tive initial radiographie evaluation. Skeletal scintigra phy will reveal an abnormality in those patients with a healthy child presents with refusal to walk and no toddler's fracture of the tibia (3,4). significant physical findings related to the lower extrem ity, particularly when there are no other clinical symp toms. In this instance, following an initial negative radiographie examination, the patient will be placed in REFERENCES a long leg cast for 7 to 10days. The cast will be removed, 1. Silverman FN, ed. In: CafFey's pediatrie x-ray diag and repeat clinical examination and radiography will nosis: an integrated imaging approach, 8th edition, be obtained following this initial period. In patients Chicago: Year Book Medical Publishers, 1985: 763. with a toddler's fracture, either a periostea! reaction or 2. Sharrard WJW. Paediatric orthopaedics and fractures, 2nd edition. Oxford: Blackwell, 1979: 1619-1629. a more obvious fracture, due to reabsorption at the 3. Sty JR. Starshak RJ, Miller JH. Bone scintigraphy. In: fracture site will be seen. The child will then be recasted Current practice in nuclear medicine: pediatrie nuclear and will continue immobilization for a total of 6 wk. medicine. Norwalk: Appleton-Century-Crofts, 1983: Skeletal scintigraphy should be obtained in those 1-25. children with clinical signs or symptoms suggestive of 4. ter Muelen EXT,Majd M. The role of bone scans in evaluating children with obscure skeletal pain. Ra the presence of an inflammatory process and lower diology 1985; 157:72. extremity pain or refusal to walk and a negative initial 5. Miller JH, Gates GF. Scintigraphy of sacroiliac pyar radiographie examination of the lower extremities (3, throsis in children. JAMA 1977; 238:2701-2704.

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