399 Perspective Osteomyelitis and Septic Arthritis in Children: Appropriate Use of Imaging to Guide Treatment Diego Jaramill& , S. Ted Treves2, James R. Kasser3, Marvin Harper4, Robert Sundel5, Tal Laor1 Modern imaging techniques have become essential compo- nents of the management of acute osteomyelitis and septic arthritis in children. This article addresses the role of these tech- niques, based on clinical practice guidelines recently developed at a children’s hospital by an interdisciplinary group. The recom- mendations reflect a review of the literature and an analysis of our own experience with 84 children treated for musculoskeletal sepsis during the past 3 years. We attempt to optimize imaging resources by analyzing the unique aspects of these infections in the pediatric skeleton, the clinical needs at different stages of the disease, and the relative strengths and weaknesses of the various imaging procedures. Our goal was to define the use of imaging in cases of osteomyelitis and septic arthritis in children in specific clinical scenarios in which additional information is likely to lead to management modification. Imaging of Acute Osteomyelitis Clinical Considerations Relevant to Imaging Osteomyelitis is difficult to diagnose and localize in the first years of life [i]. Infection almost always occurs by hematoge- nous colonization of growing bones by bacteria, usually Sta- phylococcus aureus [2]. The metaphysis is usually the site of seeding, due to sluggish flow in the sinusoidal vessels and decreased phagocytic activity [3]. The metaphysis of children is difficult to evaluate both scintignaphically and by MR imag- ing [4]. The high blood flow and significant rate of bone depo- sition in the metaphysis normally result in increased uptake of radiopharmaceuticals. Osteomyelitis producing increased tracer uptake adjacentto the physis may be difficult to detect. Meticulous imaging, including magnification scintigraphy with the pinhole collimator and comparison with the contralatenal side, is often necessary for diagnosis [5]. Similarly, metaphy- seal disease can be obscured on Ti -weighted MR images by the adjacent water-rich hematopoietic marrow. Knowledge of the normal age-related changes in distribution of marrow is important to differentiate infected edematous marrow from normal hematopoietic marrow. T2-weighted images and short inversion time inversion recovery (STIR) images usu- ally show less signal intensity in normal hematopoietic mar- now than in marrow infiltrated by infectious exudate. Certain aspects of pediatric osteomyelitis pose unique diag- nostic challenges. Infections in neonates and infants are mi- tially clinically silent. Young children may present with only limping on the refusal to bear weight [6]. In pelvic infection, inn- tation of the lumbosacral plexus can mimic lumbar disk dis- ease [7, 8], and extension into the iliac fossa can produce abdominal pain. In the spine, vertebral osteomyelitis and epi- dural abscess can present with a rapidly progressive neuro- logical deficit [9] rather than with signs of musculoskeletal sepsis. Infection tends to lodge in recently injured bones [10]; a history of recent local trauma can be obtained in one third of cases of osteomyelitis [ii]. In these children, increased tracer uptake on scintigraphy or marrow edema on MR imaging may be erroneously interpreted as posttnaumatic. Osteomyelitis in children often disrupts the blood supply to the bone, leading to focal decrease in tracer uptake. This is particularly noticeable Received January 3, 1995; accepted after revision March 6, 1995. 1 Department of Radiology, Division of Body Imaging, Children’s Hospital and Harvard Medical School, 300 Longwood Ave. , Boston, MA 0211 5. Address corre- spondence to D. Jaramillo. 2Department of Radiology, Division of Nuclear Medicine, Children’s Hospital and Harvard Medical School, Boston, MA 02115. 3Department of Orthopaedic Surgery, Children’s Hospital and Harvard Medical School, Boston, MA 02115. 4Department of Medicine, Division of Infectious Diseases, Children’s Hospital and Harvard Medical School, Boston, MA 02115. 5Department of Medicine, Division of Rheumatology, Children’s Hospital and Harvard Medical School, Boston, MA 02115. AJR i995;i65:399-403 036i-803X/95/i652-399 © American Roentgen Ray Society Downloaded from www.ajronline.org by 3.236.55.199 on 06/17/20 from IP address 3.236.55.199. Copyright ARRS. For personal use only; all rights reserved