70 Septic (Pyogenic) Arthritis

CASE 70


Septic (Pyogenic) Arthritis


Sam Y. Chun, Ali Islam, Alison Spouge, Anthony G. Ryan, and Peter L. Munk


Clinical Presentation


A 24-year-old man presented with a 10-day history of right hip pain.



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Figure 70A



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Figure 70B


Radiologic Findings


An anteroposterior radiograph of the right hip (Fig. 70A) at the time of presentation shows marked narrowing of the joint space with relative preservation of bone density. A radiograph 1 year later (Fig. 70B) shows extensive destruction of the right hip joint with near-complete loss of the femoral head and the articular portion of the acetabulum.


Diagnosis


Pyogenic (septic) arthritis.


Differential Diagnosis



Discussion


Background


Pyogenic or septic arthritis is a rapidly progressive joint disease with destructive and debilitating consequences. In the general population, the incidence of septic arthritis is ~2 to 10 per 100,000. The outcome of the disease depends on the speed of diagnosis, the organism and joint involved, and the patient’s preexisting health. Risk factors include advanced age, immunosuppression, sexually transmitted disease, diabetes, rheumatoid arthritis, joint trauma/injection, prosthetic joints, and intravenous drug abuse. Although the disease is usually monarticular, polyarticular disease occurs in up to 20% of cases.


Etiology


Staphylococcus aureus is the most common pathogen in adults, accounting for ~40% of cases. In some series, streptococci account for up to 30% and gram-negative rods up to 20%. Neisseria gonorrhoeae is the most common pathogen in young, sexually active patients, but it accounts for only 3.0 to 7.5% of overall cases. Children younger than 6 months of age are usually infected by vaginal flora that include gram-negative rods and gram-positive cocci. Between 6 months and 3 years, Haemophilus influenzae is common.


Following orthopedic procedures, both S. aureus and S. epidermidis are common causative agents.


Clinical Findings


Nongonococcal arthritis presents with a hot swollen joint that is painful throughout passive and active range of motion. Fever and signs of sepsis may also be present. Pain is present on both passive and active range of motion. The knee is the affected joint in over half of all cases in adults, followed by the hip, shoulder, wrist, ankle, elbow, and hand in order of decreasing frequency. Hip joint infections are more common in children. Infection of small joints is more common with intravenous drug abuse.


A primary source of infection can be found in almost half of all cases. The primary source is usually the skin or genitourinary or respiratory tract. Between 10 and 20% of infections are polyarticular, usually occurring in patients with collagen-vascular diseases such as rheumatoid arthritis.

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Feb 14, 2016 | Posted by in MUSCULOSKELETAL IMAGING | Comments Off on 70 Septic (Pyogenic) Arthritis

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