Before making a diagnosis of retrocalcaneal bursitis, a doctor must rule out other possible problems, such as arthritis, a fracture, or tumor. A doctor also will try to determine if the Achilles tendon itself is a source of pain.
To make a diagnosis, a doctor will use some or all of the diagnostic tools below:
Patient interview. A doctor will ask a patient about medical history, and to describe the onset of his or her symptoms, the pattern of pain and swelling, and how symptoms affect lifestyle. For example, doctors may ask patients what types of shoes they wear and what they do for exercise. A patient's reported symptoms are important to diagnosis and treatment. The doctor will also ask what home treatments have helped the condition.
Physical exam. A doctor will examine the patient's foot, noting swelling, tenderness and pain points, and range of motion. The doctor also may ask the patient to point and flex the feet and stand on his or her toes.
Imaging tests such as X-rays, MRIs, and ultrasounds. If heel pain has not responded to home treatment, X-rays may be ordered. These images can show deformities of the heel bone and bone spurs that have developed at the attachment of the Achilles. If there is swelling and/or pain that is slightly higher and within the Achilles tendon itself, an MRI may be ordered to determine if the tendon is simply inflamed or if there is a chronic tear on the tendon.
Aspiration and lab tests. If a septic bursitis is highly suspected, a doctor may perform an aspiration, removing fluid from the bursa with a needle and syringe. In addition to relieving pressure and making the patient more comfortable, it provides a fluid sample that can be tested for infection.
Common tests for infection include:
- Gram stain. A lab test called a Gram stain is used to determine if certain troublesome bacteria are present. Not all bacteria can be identified with a Gram stain, however, so even if the test comes back negative, septic bursitis cannot be completely ruled out.
- White blood cell count. An elevated number of white blood cells in the bursa's synovial fluid indicates an infection.
- Glucose levels test. Glucose levels that are significantly lower than normal may indicate infection.
Occasionally, lab tests to detect infection are negative even when an infection is present. Therefore, a doctor who strongly suspects septic bursitis may prescribe antibiotics without definitive positive lab tests.
See Septic Bursitis
A doctor will often be able to diagnose retrocalcaneal bursitis after a patient interview and exam.