CHAPTER 121 ■ MUSCULOSKELETAL EMERGENCIES MARK D JOFFE, JOHN M LOISELLE GOALS OF EMERGENCY CARE Nonfracture-related orthopedic emergencies often pose a diagnostic dilemma for even the most experienced clinician due to indolent courses and lack of distinguishing signs and symptoms The pediatric emergency clinician is challenged to make the diagnosis and institute early therapy as outcomes often correlate with the time to institution of treatment after symptoms begin The time to antibiotic administration and time to surgery are key goals for these disorders A systematic approach utilizing appropriate laboratory testing, imaging, and orthopedic consultation will most often detect these conditions Certain conditions such as septic arthritis of the hip must be diagnosed at the time of the initial visit so that surgical intervention combined with timely antibiotic therapy can minimize the likelihood of poor outcomes such as growth retardation or irreparable joint dysfunction When unrecognized or untreated, other orthopedic conditions may lead to prolonged pain, chronic functional disorders, or a delay in the ability to return to normal activity KEY POINTS A normal plain radiograph does not rule out significant disease or pathology Referred pain or the inability of the young child to localize pain can obscure the diagnosis Trauma is too often assumed to be the cause of symptoms when skeletal infection is present Presence of fever and significant elevations in inflammatory markers are useful when considering infectious etiologies Provocative physical examination testing is helpful in distinguishing certain overuse injuries Cultures should be obtained from the blood and potentially infected areas when there is concern for musculoskeletal infection RELATED CHAPTERS Signs and Symptoms Fever: Chapter 31 Immobile Arm: Chapter 38 Injury: Shoulder: Chapter 43 Limp: Chapter 46 Pain: Back: Chapter 54 Pain: Joints: Chapter 60 Medical, Surgical, and Trauma Emergencies Infectious Disease Emergencies: Chapter 94 Musculoskeletal Trauma: Chapter 111 The Children’s Hospital of Philadelphia Clinical Pathways ED Pathway for the Evaluation/Treatment of the Child With Suspected Septic Arthritis URL: http://www.chop.edu/clinical-pathway/septic-arthritis-suspectedclinical-pathway Authors: P Aronson, MD; J Posner, MD; S Dooley, RN; S Coffin, MD; C Jacobstein, MD; J Lavelle, MD Posted: July 2010, revised November 2017 Pathway for Evaluation/Treatment of Child With Fever URL: https://www.chop.edu/clinical-pathway/child-with-fever-clinicalpathway Authors: K Cohn, MD, MPH; F Balamuth, MD, PhD; R Marchese, MD; F Henretig MD; J Gerber MD, PhD; L Bell, MD; A Grossman, MD; J Hart, MD; T Metjian, PharmD; J Burham, MD; J Lavelle, MD; C Jacobstein, MD Posted: October 2018 OSTEOMYELITIS CLINICAL PEARLS AND PITFALLS Refusal to move a limb or pseudoparalysis may be a sign of osteomyelitis Up to 40% of children with osteomyelitis will be afebrile Radiographs are helpful in evaluating for alternate diagnoses but not rule out osteomyelitis when obtained early in the course of the illness Osteomyelitis is frequently associated with septic arthritis in neonates Pathogens or etiology of musculoskeletal infection vary by age of the patient Staphylococcus aureus is the most common organism in all ages Magnetic resonance imaging (MRI) is the imaging study of choice Patients with sickle cell disease are at risk for Salmonella osteomyelitis Inflammatory markers are elevated in up to 90% of cases of osteomyelitis CRP is the most effective inflammatory marker in monitoring the response to therapy The lower extremity accounts for up to 70% of cases of osteomyelitis in children Current Evidence Osteomyelitis is an inflammation of the bone and bone marrow that is most commonly of infectious origin Infection is confirmed by the presence of two of the following: pus on an aspirate of the bone, clinical findings consistent with the diagnosis, positive blood or bone aspirate cultures, and consistent findings on medical imaging Osteomyelitis is more common in boys, with the highest incidence found among infants and preschool age children Younger age and underlying disorders are associated with an increased risk for contracting osteomyelitis, as well as for the particular pathogens involved Bacteria gain entrance to the bone through one of three routes: hematogenous, direct spread from adjacent infection, or inoculation through a penetrating wound Hematogenous spread is the most common route of infection in children A transient bacteremia is believed to be the initiating event in the infection Bacteria enter the bone at the level of the metaphysis where the predominant vascular supply is located The sluggish blood flow within the microvasculature of the marrow predisposes to infection Local trauma has been suggested as a possible cause of microthrombotic events further predisposing bone to infection This is supported by an association of trauma with the occurrence of osteomyelitis and the preponderance of infections occurring within the long bones, especially those of the lower extremities In sickle cell patients, microinfarcts within the more tenuously supplied area of the diaphysis may explain the increased occurrence in this region of the bone As infection progresses, pressure increases and organisms penetrate up through the cortex to the subperiosteal space Differences in the underlying bony structure in the neonate and young infant predispose them to a higher incidence of multifocal osteomyelitis and concomitant septic arthritis The thin cortex allows easier penetration to the subperiosteal space The periosteum is less adherent in these ages and less effective in limiting the spread of infection Transphyseal vessels, which are present through the first 18 months of life, allow bacteria to gain access to the adjoining epiphysis and joint space A less common source of osteomyelitis in children is penetration of the periosteum by adjacent infections such as a cellulitis or abscess Inoculation of the bone from stepping on a nail, surgical instrumentation, or intraosseous line placement provides a third means for infection to gain entrance to the bone Goals of Treatment Early recognition and treatment of osteomyelitis prevents the spread of infection and minimizes the risk of poor outcomes such as growth disturbance, abscess formation, sepsis, chronic osteomyelitis, or even death The time to initiation of antibiotic administration from onset of symptoms or arrival to medical care is a key objective of care Empiric antibiotic treatment is based on the patient’s age, Gram stain of an aspirate if performed, the likely means of contracting the infection, and underlying comorbidity The ultimate choice of antibiotic and the length of treatment are dictated by the offending organism which is identified through appropriate cultures Although acute operative intervention is rarely necessary, timely consultation of orthopedic surgery facilitates bone aspiration when indicated and the initiation of treatment Clinical Considerations Clinical Recognition The infant or child with osteomyelitis typically presents with fever, localized musculoskeletal pain, or pain with movement Trauma is not an obvious explanation for the symptoms The absence of fever does not rule out the presence of osteomyelitis