Abstract
INTRODUCTION:
Previous modalities such as static x-rays, MRI scans, CT scans and fluoroscopy have been used to diagnosis both soft-tissue clinical conditions and bone abnormalities. Each of these diagnostic tools has definite strengths, but each has significant weaknesses. The objective of this study is to introduce two new diagnostic, ultrasound and sound/vibration sensing, techniques that could be utilized by orthopaedic surgeons to diagnose injuries, defects and other clinical conditions that may not be detected using the previous mentioned modalities.
METHODS:
A new technique has been developed using ultrasound to create three-dimensional (3D) bones and soft-tissues at the articulating surfaces and ligaments and muscles across the articulating joints (Figure 1). Using an ultrasound scan, radio frequency (RF) data is captured and prepared for processing. A statistical signal model is then used for bone detection and bone echo selection. Noise is then removed from the signal to derive the true signal required for further analysis. This process allows for a contour to be derived for the rigid body of questions, leading to a 3D recovery of the bone. Further signal processing is conducted to recover the cartilage and other soft-tissues surrounding the region of interest. A sound sensor has also been developed that allows for the capture of raw signals separated into vibration and sound (Figure 2). A filtering process is utilized to remove the noise and then further analysis allows for the true signal to be analyzed, correlating vibrational signals and sound to specific clinical conditions.
RESULTS:
Numerous tests have been conducted using this ultrasound technique to create 3D bones compared more traditional techniques, MRI and CT Scans. These tests have shown repeatedly that 3D bones can be created with an error less than 1.0 mm. Soft-tissues at the joint of question are also created with a high accuracy. Sound signals have been analyzed and correlated to specific knee and hip clinical pathology as well as complications after Total Joint Arthroplasty. Sounds such as squeaking, knocking, grinding, clicking and even a rusty door hinge have been recovered during weight-bearing activities.
DISCUSSION:
Both CT scans and x-rays emit radiation, and static CT scans and MRI scans are conducted under non weight-bearing conditions. These two new orthopaedic diagnostic techniques, ultrasound and sound, allow a surgeon to make clinical diagnoses while the patient is performing weight-bearing, dynamic activities, while not being subjected to harmful radiation. Sound analyses allow for support of the ultrasound and physical exam that can lead to enhanced diagnostics that are not possible using only a visual based analysis. Early results are promising for both of these new diagnostic techniques. This study revealed that weight-bearing, dynamic diagnoses can be made by an orthopaedic surgeon and could have distinct advantages compared to traditional techniques.
