 Introduction/Background Pediatric musculoskeletal infections can result in significant morbidity, particularly given ongoing skeletal maturation, and delayed diagnosis may result in premature physeal arrest or joint damage. Among osteoarticular infections, osteomyelitis occurs twice as frequently as septic arthritis [1]. Estimates of the incidence of pediatric osteomyelitis vary widely but have been cited between 2 to 20 per 100,000 [1-4]. Concomitant joint and bone or other extra-articular infections are common in children and may occur in >50% of cases [5-7]. Septic arthritis, which most commonly occurs in the knee and hip joints, is considered an orthopedic emergency because bacterial proliferation and metabolites can rapidly result in cartilage damage [11]. The Kocher criteria, first described in 1999, are widely applied in evaluation of the hip joint as a means to distinguish septic arthritis (surgical emergency) from transient synovitis (expectant management) [14]. The criteria include fever >101.3oF, erythrocyte sedimentation rate of at least 40 mm/hour, white blood cell (WBC) count of at least 12,000 cells/mm3, and an inability to bear weight on the affected side. Satisfying more of these criteria results in higher likelihood of septic arthritis, with near 100% likelihood in patients who meet all four criteria. More recently, elevated C-reactive protein >2.0 mg/dL has been described as an accurate predictor of septic arthritis [15]. Clinical suspicion of septic arthritis is of paramount importance in management because diagnosis is made by arthrocentesis. The distribution of septic arthritis and osteomyelitis varies by age. Children <2 years of age have been reported to be more likely to have septic arthritis than osteomyelitis (P = . 0003). In children between 2 and 10 years old, osteomyelitis is slightly more common than septic arthritis, and in children from 10 to 18 years old, septic arthritis is slightly more common [6].
Osteomyelitis or Septic Arthritis Child Excluding Axial Skeleton PCAs.  Introduction/Background Pediatric musculoskeletal infections can result in significant morbidity, particularly given ongoing skeletal maturation, and delayed diagnosis may result in premature physeal arrest or joint damage. Among osteoarticular infections, osteomyelitis occurs twice as frequently as septic arthritis [1]. Estimates of the incidence of pediatric osteomyelitis vary widely but have been cited between 2 to 20 per 100,000 [1-4]. Concomitant joint and bone or other extra-articular infections are common in children and may occur in >50% of cases [5-7]. Septic arthritis, which most commonly occurs in the knee and hip joints, is considered an orthopedic emergency because bacterial proliferation and metabolites can rapidly result in cartilage damage [11]. The Kocher criteria, first described in 1999, are widely applied in evaluation of the hip joint as a means to distinguish septic arthritis (surgical emergency) from transient synovitis (expectant management) [14]. The criteria include fever >101.3oF, erythrocyte sedimentation rate of at least 40 mm/hour, white blood cell (WBC) count of at least 12,000 cells/mm3, and an inability to bear weight on the affected side. Satisfying more of these criteria results in higher likelihood of septic arthritis, with near 100% likelihood in patients who meet all four criteria. More recently, elevated C-reactive protein >2.0 mg/dL has been described as an accurate predictor of septic arthritis [15]. Clinical suspicion of septic arthritis is of paramount importance in management because diagnosis is made by arthrocentesis. The distribution of septic arthritis and osteomyelitis varies by age. Children <2 years of age have been reported to be more likely to have septic arthritis than osteomyelitis (P = . 0003). In children between 2 and 10 years old, osteomyelitis is slightly more common than septic arthritis, and in children from 10 to 18 years old, septic arthritis is slightly more common [6].