Microphone: A new modality for diagnosing knee osteoarthritis

Osteoarthritis (OA) of the knee joints:

Osteoarthritis (OA) of the knees is a quite common degenerative joint condition in the general elderly population. It can affect any joints of the body but the knee joints are most commonly damaged. At present, X-ray is the initial and commonly used investigation modality to diagnose, assess the severity and monitor the disease progression. But a new, non-harmful method (e.g. no radiation hazard) is on the horizon to replace the X-ray in a knee arthritis patient; a study suggests which was published in PLOS One.

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A new study and a new diagnostic modality:

The study was conducted by the researchers from Lancaster University, the University of Central Lancashire and Manchester University. They used a special type of tiny microphone, a technology used by the engineers to hear the faults in bridges, to listen the noisy sound produced by the diseased (damaged due to osteoarthritic process) knee. A group of 89 adults suffering from osteoarthritis took parts in the study. The researchers attached a tiny microphone sensor to the participant’s knee which captured high-frequency sounds and sent to the computer. The computer analyzed the waveform to give an insight into the knee joint.

Although grating or crackling sounds can be heard and felt in an advanced stage of osteoarthritis, the sound wave analyzed by this study wasn’t audible by the human ear. They had to depend on the analysis made by the computer. They found that the more severe the disease was, the noisier was the knees and more hits were visible on the waveforms. Following the study, the researchers have commented that comparing various waveforms, it is possible to determine the status of the joints; healthy or diseased one. The severity of the disease can also be assessed in a more sensitive manner without any necessity of the X-ray.  

If two smooth and well-lubricated surfaces move against each other, no sound is usually produced. On the other hand, uneven and poorly-lubricated surfaces produce more acoustic signals. This is the principle for the engineering structures. The same principle is applicable to a joint. If the participant bone-ends of a joint are smooth, even and well-lubricated with synovial fluids, there shouldn’t be any sound. When the articular surfaces are damaged due to the generative process as seen in osteoarthritic joints, the sounds are generated. This study depends on the principle as well.

Prof John Goodacre, the lead researcher of the study, from the Lancaster University said the technique as a promising one. He also said that this technique could open the door to the more personalized treatment considering the particular characteristics of a patient’s joint condition. But he urges for more researches with the hope of discovering new approaches which can be used as a diagnostic tool as well as a prognostic tool to monitor the response to the treatment. To be noted, this study was conducted for the knee joints osteoarthritis. It is not tested on other joints (hip or hand or ankle) osteoarthritis.

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