According to Gaetano Scuderi, professor of orthopaedic surgery and leader of the research team, the knee joint has two crescent shaped menisci comprised of cartilage. Menisci are often torn by physical activity or natural degradation, but these tears are not always painful or noticed.
While surgeons can use MRIs to try to discern the root of a patient’s knee pain, MRIs often cannot differentiate between inflammations from natural degeneration and a full-fledged tear.
“Traumatic and degenerative injuries look the same on MRI,” Scuderi said. “In a 50-year-old, we can’t tell the difference.”
However, correctly identifying a cartilage tear is only one obstacle. Sometimes, patients sustain pain after corrective surgery because the tear is not actually the root of pain.
“Sometimes you would think you did a great job but the patient still had pain,” Scuderi said. “Why did this person not get better when another person did?”
According to Scuderi, MRI scans of people with no previously known knee problems sometimes reveal incidental meniscus tears. Since an imaging study cannot identify pain due menisci tears, there must be another responsible mechanism, he said.
“Tapping the joint for biomarkers is more likely to tell us of actual processes inside the joint rather than an imaging study which tells us anatomy,” Scuderi said.
This new biomarker assay acts as a “truth serum” to identify the source of the patient’s pain. The study took a sample of synovial fluid in the knees of 30 patients with pain, mechanical symptoms and MRI findings consistent with menisci tears. Synovial fluid was also aspirated from 10 asymptomatic patients—those with no knee pain, despite imaging evidence of menisci tears.
The study found comparatively high levels of fibronectin-aggrecan complex in those patients with pain in contrast to asymptomatic patients. As a result, fibronectin-aggrecan complex was deemed a biomarker for knee pain related to menisci tears.
According to the study, protein biomarkers can be utilized as diagnostic tools, prognostic indicators and candidates for future drug therapies.
In a clinical setting, this biomarker could effectively differentiate knees with pain-inducing menisci tears that are responsive to surgery from knees with only natural cartilage degradation.
This is especially beneficial to older patient populations. For this group, MRIs “are a waste of time because they always show degeneration,” Scuderi said. A biomarker test offers a cheaper and more specific identification of pathology.
The research team includes researchers at New York University, the University of Pittsburgh, Jupiter Medical Center in Florida and Cytonics, Inc. It hopes to image the molecule noninvasively as opposed to aspirating it for assay.