Physicians may be able to predict which patients with knee osteoarthritis (OA) will be subject to severe pain by determining whether meniscal lesions are contributing to neuropathic pain (NP) in the knee, according to an article published online December 14 in Arthritis Research & Therapy.
Using magnetic resonance imaging (MRI) to make a diagnosis of NP could help physicians determine which patients may benefit from a treatment aimed at NP symptoms, rather than prescribing prolonged use of anti-inflammatory drugs or narcotic analgesics.
Camille Roubille, MD, from the Osteoarthritis Research Unit, University of Montreal Hospital Research Center, Quebec, Canada, and colleagues conducted an observational pilot study involving 50 patients with moderate to severe knee OA aged 40 years and older being treated at multiple ambulatory clinics.
Of the 50 patients, 25 had unlikely NP, 9 had uncertain, and 16 had likely NP, based on patients’ answers to questions on the PainDETECT NP diagnosis questionnaire.
Nociceptive Pain or NP
“[OA] patients have been found to experience both nociceptive and neuropathic pain to varying degrees. Currently, symptomatic treatments of knee OA mainly target nociceptive pain, whereas NP needs to be assessed and appropriately managed,” Dr Roubille told Medscape Medical News.
The investigators performed MRI exams on target knees within 21 days of study recruitment, measuring cartilage volume and determining whether meniscal tears existed in the anterior horn, body, or posterior horn of the meniscus. None of the patients received NP treatment.
The authors found that meniscal extrusion in both medial (P = .006) and lateral (P = .023) compartments was significantly associated with increasing PainDETECT scores and that meniscal tears in the lateral compartment were significantly associated with increasing scores (P = .011).
They also found that bone marrow lesions in the lateral plateau were significantly associated with PainDETECT scores (P = .032).
These results “suggest that knee OA patients with a neuropathic component of pain have more severe symptoms, which appear related to meniscal lesions, more specifically extrusion, and are reflected, to a certain extent, by a trend toward a greater consumption of non-steroidal anti-inflammatory drugs,” the investigators write.
“The present study is the first to report such an association between meniscal lesions, more specifically extrusion, and NP,” Dr Roubille toldMedscape Medical News. “The association between the presence of meniscal extrusion and the PainDETECT scores makes it a definite marker of NP.”
Clinically Relevant
“This finding is clinically relevant for various reasons,” she said.
First, it points to a pathophysiological relationship between NP and meniscal extrusion in knee OA.
“Hence, physicians should first ask for NP in their knee OA patients, and then search for meniscal extrusion in those reporting NP,” she said. “This suggests that in daily practice, the predominance of a NP component in such patients should encourage physicians to consider the use of knee MRIs to establish a proper diagnosis.”
“Second, there is hope that this ‘personalized therapeutic management’ would avoid the unnecessary prolonged use of anti-inflammatory drugs, or even narcotic analgesics, preventing potential side effects, and that the patients would have a better response to treatment,” she continued.
What’s needed now, she added, is a study with a larger number of participants to confirm these results. “Future research might also explore whether the surgical management of meniscal extrusion in such knee OA patients with NP could be beneficial.”
This research was supported by Merck & Co, the Chair in Osteoarthritis of the University of Montreal, and the CHUM Foundation. Seven authors are shareholders, consultants, or employees of ArthroLab, maker of the MRI system used in the study. The other authors have disclosed no relevant financial relationships.
Arthritis Res Ther. Published online December 14, 2014. Full text