By Abby Sims
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Mets infielder Wilmer Flores was placed on the disabled list on Friday and spent the weekend in the hospital to receive IV treatment for a knee infection. Evidently, Flores had played with discomfort for a couple of days before seeking medical attention.
Though this diagnosis may not sound like much, it is one that can be quite serious. It is considered an emergent condition with high risk of morbidity or mortality if not quickly and aggressively addressed. The outcome of treatment hinges on it.
There are a number of possible causes of joint infections, also known as septic arthritis. These include being spread via the bloodstream (hematogenous dissemination), postoperative wound infection, localized steroid injections, diagnostic procedures (or drug use) involving puncture, and open traumatic injury of the joint.
Localized symptoms typically include swelling, redness and warmth of the affected joint, pain, and restricted joint mobility. Generalized symptoms may include fever and accompanying chills, fatigue and an overall sense of weakness.
Septic arthritis is diagnosed by extracting a sample of the synovial fluid that bathes and lubricates the joint. This enables identification of the specific bacteria causing the infection and will reveal an elevated white blood cell count, indicating that the body is fighting infection. A complete patient history, along with a physical exam also provides useful information, as do imaging studies. X-rays can reveal any joint damage, and, in later stages, MRI studies can do likewise.
Those with a weakened immune system, diabetes, rheumatoid arthritis, open wounds, or chronic skin infections are more predisposed to suffering from septic arthritis and may have a more difficult recovery. Those who’ve sustained trauma, have a malignant cancer, or have severe genitourinary or gastrointestinal infections are also more vulnerable. The very old and very young are at higher risk.
The Bacteria Involved
Determining the type of bacteria causing the infection is key to driving the treatment. Most commonly implicated is Staphylococcus aureus (referred to as a Staph infection), with Streptococci (strep) infections also common. Other organisms diagnosed less often include: Pneumococci, Escherichia coli, Staphylococcus epidermidis, Borrelia burgdorferi as well as assorted others.
Draining the joint with a syringe and irrigating it (also known as lavage) via arthroscopy to clear it of infection is the first step in treating septic arthritis. In more severe cases, it may be necessary to repeat these procedures. The scope may also be used to debride affected tissue. Systemic antibiotic therapy targeting the specific organisms identified is a crucial part of treatment. Severe cases may require surgery. Physical therapy is an integral part of treatment to restore soft tissue and joint mobility.
Those with joints infected by particularly virulent bacteria or who have septic arthritis in multiple joints have a poorer prognosis despite optimal care. In addition, patients who delayed treatment for seven or more days typically respond more slowly to antibiotics and evidence the worst outcomes.
While the most persistent cases may fail to respond to treatment, some patients, even after recovery, may suffer a recurrence. One study reported a 91 percent “cure” rate, with only 4 percent of patients requiring revision surgery. Another study reported an 89.2 percent success rate overall, up from 78.3 percent after administering a second round of treatment to those with recurrent infection.
Research indicates that joint function is permanently reduced in 10-73 percent of those who’ve suffered from septic arthritis. This wide variance is due to the underlying condition of the patients, as well as the many diagnostic and treatment factors in play. Studies have shown that the mortality associated with septic arthritis is between 5 and 20 percent.
Abby Sims is a licensed physical therapist with vast experience evaluating and treating orthopedic, sports and dance injuries. Follow her on Twitter @abcsims