Working Diagnosis:
Our final diagnosis was septic arthritis of the right hip.

Treatment:
He underwent fluoroscopic right hip arthrocentesis with purulent drainage noted. Fluid analysis showed a leukocytosis of 58,480, with 89% polymorphonuclear leukocytes, and Gram positive cocci. This prompted emergent right hip arthrotomy with irrigation and debridement. He was weight bearing as tolerated with early mobilization through physical therapy by postoperative day 1. Intravenous Vancomycin and Cefepime were de-escalated to intravenous Oxacillin once blood and fluid cultures grew methicillin-susceptible Staphylococcus aureus.

Outcome:
The patient followed with Pediatric Infectious Disease and Orthopedic Surgery at 2 weeks post discharge. He continued intravenous antibiotics for two weeks, followed by 5 weeks of oral Cephalexin. Inflammatory markers down-trended. Repeat x-rays were unremarkable. One year later, he was doing well playing tackle football as a high school freshman without any limitations.

Author's Comments:
Pediatric septic hip is an orthopedic emergency. The joint is often infected through a hematogenous route by Staphylococcus aureus. Patients may present with acute onset hip pain, limping or non weight bearing. Although more commonly in males under two years old, septic hip should still be considered in older children especially in the setting of fever and non weight bearing. Clinicians should maintain a high index of suspicion and a low threshold to repeat work up if the clinical picture is not improving. To confirm the diagnosis, clinicians can use the modified Kocher criteria (non weight bearing status, fever greater than 101.3 degrees Fahrenheit, leukocytosis greater than 12,000, erythrocyte sedimentation rate greater than 40 mm/hr, and c-reactive protein greater than 2 mg/dL), imaging, as well as analyses of aspirated joint fluid. Patients should be treated within 4 days of symptom onset for a good prognosis. If treatment is delayed, grave outcomes can occur.

Editor's Comments:
A septic joint is considered an orthopedic emergency. Early recognition and treatment are vital. Spetic arthritis should be considered in anyone with inability bear weight along with a fever. In this case, the patient continued with fevers and inability to bear weight despite initial treatment. The early recognition allowed the patient to have a good prognosis. If treatment is delayed, the joint can be compromised and even lead to death. As in this case, once a septic joint is considered a arthrocentesis should be performed to help aide in the diagnosis and treatment. Treatment consists of arthrotomy with irrigation and debridement. Patients are also given intravenous antibiotics and with consultation of infectious disease will be switched to oral antibitoics for several weeks.

References:
Adam M, Ibrahim B, Khidir R, et al. Usefulness of MRI findings in differentiating between septic arthritis and transient synovitis of hip joint in children: A systematic review and meta-analysis. Eur J Radiol Open. 2022 Aug 26; 9:100439.

Bisht RU, Burns JD, Smith CL, et al. The modified Kocher criteria for septic hip: Does it apply to the knee? J Child Orthop. 2022 Jun; 16(3):233-237.

Caird MS, Flynn JM, Leung YL, et al. Factors distinguishing septic arthritis from transient synovitis of the hip in children. J Bone Joint Surg Am. 2006; 88(6): 1251-1257.

Cook PC. Transient synovitis, septic hip, and Legg-Calve-Perthes disease: an approach to the correct diagnosis. Pediatr Clin North Am. 2014 Dec; 61(6): 1109-18.

Habusta SF, Mabrouk A, Gregush RE. Septic Hip Joint. 2022 Feb 7. In: StatPearls [Internet]. Treasure Island (FL). StatPearls Publishing; 2022 Jan.

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