High Yield Topics

Septic Hip

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Ovid: 5-Minute Orthopaedic Consult

Editors: Frassica, Frank J.; Sponseller, Paul D.; Wilckens, John H.
Title: 5-Minute Orthopaedic Consult, 2nd Edition
> Table of Contents > Septic Hip

Septic Hip
Tariq A. Nayfeh MD, PhD
Simon C. Mears MD, PhD
Basics
Description
  • The incidence of septic hip is increasing, especially in elderly and immunosuppressed individuals.
  • This condition may occur in infants, children, adults, and the elderly, but it is more common in the pediatric population.
  • Risks factors include hip surgery (most common cause), intravenous drug abuse, alcoholism, and steroid use.
Epidemiology
Incidence
  • In children, the hip may be the most common site of joint infection (1).
  • In adults, infected knees are more common than infected hips (2).
  • The rate of infection after total hip replacement is ~2% (3).
Risk Factors
  • Local factors:
    • Previous surgery
    • Previous hip replacement
    • Intra-articular hip injection
    • Osteoarthritis
    • AVN
    • Previous trauma
  • Systemic factors:
    • Immunosuppression
    • Intravenous drug abuse
    • Hemophilia
    • Seronegative arthritides
    • Sickle cell disease
Pathophysiology
  • Direct inoculation secondary to surgery is a common cause of infection in the adult hip.
  • Hematogenous spread is more common in the pediatric population than in the adult.
  • Sources include:
    • Urinary tract
    • Lung
    • Skin Infections
Etiology
  • Bacteria in the blood lodge in the
    vascular synovial membrane or enter directly through a damaged joint
    capsule or diseased synovium.
  • Common organisms:
    • Staphylococcus aureus:
      • The most common organism in both children (1) and adults (4).
  • Streptococcus species
  • Gonococcus
  • Pseudomonas species
  • Escherichia coli
  • Salmonella
  • Klebsiella
  • Myobacterium tuberculosis
  • Brucella
Associated Conditions
  • Hemophilia
  • Sickle cell disease
  • Intravenous drug abuse
  • Immunosuppression
Diagnosis
Signs and Symptoms
  • Pain in the groin and/or inner thigh
  • Fever and occasionally chills
  • Concurrent source of infection
History
  • Pain in the affected hip is the most common complaint.
  • Occasionally patients present with isolated pain in the ipsilateral knee.
Physical Exam
  • Fever
  • Skin changes such as a rash or decubitus ulcer
  • Gait disturbances such as antalgic gait or the inability to ambulate
  • Hip examination:
    • Tenderness
    • Hip held in flexion, external rotation
    • Restricted and painful ROM
Tests
Lab
  • Laboratory tests are unreliable, especially in the immunocompromised patient.
  • Elevated ESR
  • Elevated C-reactive protein
  • White blood cell count may or may not be elevated.
    • Usually an elevated percentage of polymorphonuclear leukocytes is present.
  • Hip aspiration
  • Blood cultures
Pediatric Considerations
  • Diagnosis in the neonatal and pediatric population is difficult.
  • The most sensitive factors are thought to
    be fever >38.5°C, inability to bear weight, elevated ESR, and
    C-reactive protein >2.0 mg/dL (5).
Imaging
  • Plain radiography:
    • May remain normal for up to 2 weeks
    • Early findings include widening of the teardrop interval.
    • Late findings include erosive and absorptive changes of surrounding bone and destruction of the femoral head.
  • Nuclear scans
  • MRI:
    • May show soft-tissue abnormality, pelvic fracture, or osteomyelitis or retroperitoneal fluid
    • No studies show its usefulness in the diagnosis of septic arthritis.
  • Ultrasound:
    • Valuable to show effusion in the neonatal and pediatric age groups
    • Used to guide aspiration
Diagnostic Procedures/Surgery
  • Hip aspiration is the most important test in diagnosis.
    • Elevated white blood cell count (100,000–250,000)
  • Positive joint fluid culture
  • Occasionally a positive Gram stain
Pathological Findings
  • Rapid destruction of the femoral head and acetabulum
  • Late findings include septicemia, subluxation, deformity, and ankylosis.
Differential Diagnosis
  • Crystalline arthropathy
  • Inflammatory arthritis
  • Rheumatoid arthritis
  • Hemophilia
  • Transient synovitis of the hip

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Treatment
Initial Stabilization
  • Early diagnosis is the key to joint preservation and possibly to patient survival.
  • Initiation of empiric antibiotics after joint fluid is obtained
  • Diagnosis in neonates and children is
    particularly difficult, and the use of regimented guidelines has been
    found to be helpful (6).
  • Diagnosis in the presence of a prosthetic
    joint also may be difficult because cultures may be negative even in
    the presence of infection (7).
Medication
  • After obtaining fluid for cultures and sensitivities, antibiotics based on history and Gram stain should be started immediately.
  • The antibiotics can be tailored after obtaining identification of the infecting organism.
Surgery
  • Open surgical drainage and débridement are the mainstays of treatment.
  • Case series have reported on using hip arthroscopy to débride the hip (8).
  • If the patient is too ill to undergo surgery, serial aspirations can be performed.
  • Treatment of the infected prosthetic joint (9):
    • Suppressive antibiotics alone: Used only in patients who cannot tolerate surgery
    • Washout and retention of the components: Useful if the infection is not chronic and the components are stable
    • 1-stage revision surgery:
      • Only 1 surgery for both débridement and revision of the prosthesis
      • Controversial, but may have higher failure rates than 2-stage treatment
    • 2-stage revision surgery is the most reliable method for eradicating infection.
  • Treatment of the late sequelae of hip infection is difficult.
    • In children, may include pelvic osteotomy, hip fusion, or hip resection (10)
    • In the adult, may include hip resection or 2-stage hip replacement (11)
Follow-up
Disposition
Issues for Referral
  • All patients with painful hips should be referred quickly to an orthopaedic surgeon to rule out sepsis.
  • The importance of a quick diagnosis cannot be overemphasized.
  • Antibiotics should not be started until cultures are obtained.
Prognosis
  • If diagnosis and treatment are initiated early, prognosis usually is good.
  • Outcomes usually are poor if treatment is delayed.
  • Infection and osteomyelitis with methicillin-resistant S. aureus is thought to have a worse prognosis than that from methicillin-sensitive organisms (1).
Complications
  • Osteomyelitis
  • Septicemia
  • Degenerative joint disease
  • Deformity
References
1. Wang
CL, Wang SM, Yang YJ, et al. Septic arthritis in children: Relationship
of causative pathogens, complications, and outcome. J Microbiol Immunol Infect 2003;36:41–46.
2. Abid N, Bhatti M, Azharuddin M, et al. Septic arthritis in a tertiary care hospital. J Pak Med Assoc 2006;56:95–98.
3. Ridgeway S, Wilson J, Charlet A, et al. Infection of the surgical site after arthroplasty of the hip. J Bone Joint Surg 2005;87B:844–850.
4. Eder L, Zisman D, Rozenbaum M, et al. Clinical features and aetiology of septic arthritis in northern Israel. Rheumatology 2005;44: 1559–1563.
5. Caird
MS, Flynn JM, Leung YL, et al. Factors distinguishing septic arthritis
from transient synovitis of the hip in children. A prospective study. J Bone Joint Surg 2006;88A:1251–1257.
6. Kocher
MS, Mandiga R, Murphy JM, et al. A clinical practice guideline for
treatment of septic arthritis in children. Efficacy in improving
process of care and effect on outcome of septic arthritis of the hip. J Bone Joint Surg 2003;85A:994–999.
7. Della Valle CJ, Zuckerman JD, Di Cesare PE. Periprosthetic sepsis. Clin Orthop Relat Res 2004;420:26–31.
8. Kim SJ, Choi NH, Ko SH, et al. Arthroscopic treatment of septic arthritis of the hip. Clin Orthop Relat Res 2003;407:211–214.
9. Hanssen AD, Spangehl MJ. Treatment of the infected hip replacement. Clin Orthop Relat Res 2004;420:63–71.
10. Choi IH, Shin YW, Chung CY, et al. Surgical treatment of the severe sequelae of infantile septic arthritis of the hip. Clin Orthop Relat Res 2005;434:102–109.
11. Cherney DL, Amstutz HC. Total hip replacement in the previously septic hip. J Bone Joint Surg 1983;65A:1256–1265.
Additional Reading
Zacher J, Gursche A. “Hip” pain. Best Pract Res Clin Rheumatol 2003;17:71–85.
Miscellaneous
Codes
ICD9-CM
711.95 Septic arthritis, hip
FAQ
Q: How is a septic hip diagnosed and treated in a child?
A:
The clinical signs are pain and swelling in the hip, inability to walk,
and fever. ESR and C-reactive protein tests should be checked. If
levels are elevated, the suspicion for sepsis is high. The joint should
be aspirated and antibiotics should be started. If infection is found,
the hip should be treated surgically with arthrotomy.

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