For anyone with a total hip replacement (THR), hip pain is a red flag. Medical evaluation is important because of the risk of joint infection. Treatment depends on knowing if there is (or isn’t) an infection.
There are many possible causes for the pain you are having. They may or may not be related to the implant. The first thing the orthopedic surgeon will examine is the hip itself. Your history along with the clinical presentation are very helpful. But then the spine (above) and the knee (below) will be tested as possible sources of referred pain.
X-rays and lab tests may be needed to rule out a fracture, implant loosening or infection. Other possible causes include bursitis, ossification (bone formation in the muscle or surrounding soft tissue), or synovitis. Cultures of the joint taken directly from the area during surgery are the most accurate way to confirm (or rule out) joint infection.
But this type of testing is not practical for the patient who doesn’t have an infection or who doesn’t need surgery. And there is a fair amount of false-positive test results with intraoperative cultures due to errors in sampling technique.
Instead, the physician may rely on lab tests that are sensitive, reliable, and accurate with a low false-positive and high true-positive results. The following tests may be needed to evaluate for hip infection: erythrocyte sedimentation (SED rate), C-reactive protein (CRP), and synovial fluid white blood cell count (WBC).
Don’t wait to get tested. See your surgeon now. Early diagnosis can prevent a lot of complications from delayed treatment.