CASE:
40yoM no PMHX with a swollen, painful right hip joint. Worsening x5 days. No history of prior episodes, no other joints involved, no fever, no trauma, no GU symptoms, no rash, no vision changes, no IVDU.
On exam, pt is afebrile, nontoxic appearing.
The hip is warm. You are able to range his hip, with moderate pain. There is tenderness when compressing the joint space. Strength exam limited by pain.
Sensation and pulses are intact distally.
Plain films are unremarkable. CT of hip unremarkable.
You consult your friendly orthopedist for further evaluation and to assist with a tap of the hip to rule out septic arthritis. The consultant comes down to examine the patient, ranges the hip (with pain), and gladly tells you, “nope, it’s not septic if it ranges”. End of story?
Being that orthopedic surgeons have the experience of managing septic joints, taking them in the OR and viewing the amount of destruction and purulent material that can accumulates in the joint, one may be impressed by their clinical acumen in assessing an inflamed joint in the ED.
However, when evaluating an acutely painful, swollen joint, history and physical exam are not supported by literature to sufficiently lower pretest probability to avoid further workup, namely, arthrocentesis. That being said, absence of evidence is not evidence of absence, there is always room for judgment and experience, cough art of medicine cough. For instance, by the above reasoning falling on an outstretched hand, hearing a pop, and presenting with an acutely painful and deformed wrist would warrant a tap to rule out septic arthritis.
But, the data that we have, neatly assembled in a systematic review from JAMA in 2007, inform us that only one clinical finding, fever, has a valid likelihood ratio derived a case-control trial of septic arthritis. And having a fever actually decreases the likelihood of having septic arthritis +LR 0.67 [0.43-1.00] –LR 1.7 [1.0-3.]. No other physical exam findings of a painful joint have been validated as predictive by study data, including range of motion, edema, or tenderness.
So, if there is clinical suspicion of septic arthritis in an acutely painful joint, a tap is likely warranted, regardless of the physical exam.
REFERENCES:
Margaretten ME, Kohlwes J, Moore D, Bent S. Does this adult patient have
septic arthritis? JAMA. 2007 Apr 4;297(13):1478-88
Sharff KA, Richards EP, Townes JM. Clinical management of septic arthritis.
Curr Rheumatol Rep. 2013 Jun;15(6):332.
