Haemophilus parainfluenzae septic arthritis following orthopedic procedures in immunocompetent patients with diverse management: A case report of 2 rare cases.

RATIONALE: H. parainfluenzae is an uncommon cause of musculoskeletal infection, particularly after orthopedic procedures. PATIENT CONCERNS: Two cases of H. parainfluenzae infection in immunocompetent patients following reverse shoulder arthroplasty and arthroscopic knee procedures. DIAGNOSES: H. parainfluenzae was identified as the causative pathogen through synovial fluid culture. Case 1 was identified as periprosthetic joint infection of the shoulder, and Case 2 as septic arthritis of the knee. INTERVENTIONS: Case 1 was managed with needle aspiration and oral antibiotics. Case 2 underwent arthroscopic debridement and received antibiotic therapy. OUTCOMES: Both patients recovered without recurrence of infection following appropriate treatment. In Case 2, the patient's C-reactive protein levels decreased from 18.3 mg/dL at presentation to 0.217 mg/dL by postoperative day 36, indicating resolution of inflammation and restoration of function. LESSONS: These cases highlight the potential of H. parainfluenzae infection in healthy individuals and underscore the importance of accurate diagnosis and appropriate management to ensure favorable outcomes.