Acoustic Emission Measurement System in Diagnostic of Cartilage Injuries of the Knee
Abstract The measurement system BONEDIAS (Bone Diagnostic System) was developed as a non-invasive diagnostic method, based on the analysis on the acoustic emission from the knee joint. Knee squats of a patient will release acoustic emission in high temporal resolution and well correlated to the a...
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The measurement system BONEDIAS (Bone Diagnostic System) was developed as a non-invasive diagnostic method, based on the analysis on the acoustic emission from the knee joint. Knee squats of a patient will release acoustic emission in high temporal resolution and well correlated to the angle of knee flexion. The physician will get the relevant information concerning arthritic lesions in the knee joint (well characterized acoustic emission, singular events without a follow up of further emission), acoustic emission due to elevated intra-articular friction caused by e.g. cartilage lesions, inappropriate surface roughness, a lack of synovial fluid or crack initiation in the femur. Over 100 patients were analyzed with the measurement system BONEDIAS, afterwards the results were compared with the intra-operative views (arthroscopy and arthroplasty of the knee). Other parameters were studied, concerning the relation between the age and the sex of the subjects, the length of the femur, thigh thickness, the body mass index, the anatomical axis of the knee and the appearance and severity of the cartilage lesions.
The study was made with the purpose to see if there was a correspondence between the cartilage disorders, the intraoperative views (arthroscopy and the arthroplasty of the knee) and the acoustic emission measurements, performed one day before the surgery. Because there arent at this moment cheap and standards methods who can determine the early cartilage injuries, this study is supposed (concording with the results) to open new ideas and new advantages in the diagnostic of this often disease, using the acoustic emission measurement system.
The results obtained, 50% correspondence for the gr. 0, I and II Outerbridge lesions are more important, more significant that the other results, with over 60% correspondence for the advanced osteoarthrosis. The obtained acoustic emission signals, corresponding to the intra-arthroscopic findings showed the importance of this method to identify the early cartilage injuries. The method is not perfect and the results (50%) are not really statistically significant, so that we can introduce this method on a large scale, but offers important information that should be used in the future. Also, there isn’t a perfect method to compare the acoustic emission signals with the intra-arthroscopic findings. Every patient was analysed separately and with his corresponding measurement compared, that means a lot of time (20 – 30 minutes for the measurement and the other questions and clinical tests and another 15 minutes to analyse the signals and compare them with the intra-operative findings). For a study this can be accepted, but for clinical every day use maybe not. A standard interpretation and analyse method, maybe after clinical large trials, if such a method can be developed, could bring big advantages for the early determination of the cartilage injuries.
In conclusion, the study had offered important informations about the importance of accoustic emission measurements, that can be used for the future studies and with some improvements, this method , cheap and non-invasive, but at this moment a little beat time-consuming, can be helpful in the diagnose of the early cartilage injuries.|