Septic arthritis of the hip is considered a surgical emergency in a child. Timely diagnosis and expeditious surgical treatment are essential for both treatment of the infection and avoidance of adverse sequelae, including osteonecrosis of the femoral head.
Patients will typically present with hip pain, reluctance to move the hip joint, and inability to bear weight on the affected limb. An accompanying fever is also common.
Plain radiographs of the hip are helpful during initial evaluation and may rule out other conditions within the differential diagnosis, including but not limited to: Fracture, slipped capital femoral epiphysis, Legg-Calve-Perthes disease, irritable hip syndrome and osteomyelitis.
Laboratory studies are routinely obtained, including peripheral white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels. These laboratory results may help distinguish septic arthritis from transient synovitis or inflammatory arthritis of the hip. Prior studies have suggested that patients with fever > 38.5 degrees Celsius, inability to bear weight on the affected limb, peripheral WBC count > 12,000 cells/mm3, and ESR > 40mm/hr have high likelihood for having septic arthritis of the hip.
In patients in whom there is a clinical suspicion of septic arthritis, ultrasonography may be performed to confirm the presence of a hip effusion. If an effusion is present, under ultrasonographic or fluoroscopic guidance, an arthrocentesis may be performed. Joint fluid with greater than 50,000 WBC cells/mm3 is concerning for septic arthritis.
Once the diagnosis of septic arthritis is made or considered, emergent surgical incision and drainage is recommended as the definitive therapeutic treatment, followed by appropriate antibiotic therapy.
- Patients are typically placed in the supine position.
- An oblique incision 2-3 fingerbreadths below the inguinal crease, lateral to the palpable femoral pulse is made.
- Superficial dissection is performed to develop the interval between the sartorius medially and tensor fascia lata laterally. Care is made to avoid iatrogenic injury to the lateral femoral cutaneous nerve.
- Deep dissection is performed to develop the intermuscular interval between the rectus femoris medially and the gluteus medius laterally. The ascending branch of the lateral femoral circumflex artery runs along the lateral border of the rectus femoris and should be retracted or cauterized.
- After sweeping away the superficial pericapsular fat, a 1cm x 1cm arthrotomy is made in the hip joint. Specimens may be taken for gram stain and microbial cultures.
- The hip joint is then copiously irrigated and debrided.
- A drain may then be placed within the depth of the wound, followed by loose approximation of the skin.
Key anatomic features of the surgical approach to the hip including understanding the superficial and deep intermuscular intervals:
- Sartorius – Tensor fascia lata
- Rectus femoris – Gluteus medius
Surgical irrigation and debridement is the definitive treatment for septic arthritis of the hip.
Irrigation and debridement of the pediatric septic hip is performed under general anesthesia.
- Post-operatively, patients are admitted to the hospital and placed on appropriate systemic antibiotic therapy.
- Serial clinical examinations with or without laboratory tests (WBC, ESR, CRP) are performed to ensure improvement.
- Repeat surgical debridement may need to be performed in patients who fail to demonstrate the anticipated clinical improvements after the index procedure.
- Persistent infection due to late presentation, underlying osteomyelitis, or suboptimal initial debridement.
- Osteonecrosis or chondral degeneration due to delayed presentation and/or surgical treatment.
- Heyworth BE, Shore BJ, Donohue KS, Miller PE, Kocher MS, Glotzbecker MP. Management of pediatric patients with synovial fluid white blood cell counts of 25,000 to 75,000 cells/mm3 after aspiration of the hip. J Bone Joint Surg Am 2015; 97: 389-395.
- Kocher MS, Zurakowski D, Kasser JR. Differentiating between septic arthritis and transient synovitis of the hip in children: an evidence-based clinical prediction algorithm. J Bone Joint Surg Am 1999; 81: 1662-1670.
- Hunka L, Said SE, MacKenzie DA, ROgala EJ, Cruess RL. Classification and surgical management of the severe sequelae of septic hips in children. Clin Orthop 1982; 171: 30-36.