Find out how effective a Marcaine injection might be for detecting a loosened knee replacement (failed TKR).
If your doctor suspects that you have a failed total knee replacement (TKR), he might give you an injection of an anesthetic called Marcaine (bupivacaine). He may even term the procedure as a “Marcaine diagnosis.”
Effectiveness of Marcaine Injection
It sounds too good to be true, that all a doctor need do is inject your knee, wait a bit, and then voila, he can tell if you have a loosened knee implant.
“The gold standard is serial X-rays and follow-up exam,” says Henry Boucher, MD, clinical instructor of Adult Reconstruction, Medstar Union Memorial Orthopaedics, Baltimore, MD.
“These diagnose the vast majority of loose implants. The injection is best to determine if the knee is the actual cause of pain (rather than a referred or external source), but it does not give the exact diagnosis.”
In other words, the Marcaine injection will alert the physician that the source of pain originates in the knee, rather than the lower back or hip.
However, just what’s going on in the knee (e.g., failed implants) cannot be determined by the Marcaine injection.
Symptoms of a Failed Knee Replacement
An implant may loosen or fail soon after the operation or years after. The following are suspicious symptoms.
Pain during rest or while simply bending the knee a bit while changing position in a chair. The pain may be a feeling of soreness or severe, and is suggestive of excess fluid in the knee.
Abnormal gait (walking) pattern. However, a normal gait does not rule out a failed or loosened knee replacement.
The surgical knee feels “hot.”
The knee is swollen, reddish or has a rash.
Stiffness and reduced range of motion (more so than what a knee replacement in and of itself would normally cause).