Understanding the Biomechanics of Osteoarthritis Pain

Osteoarthritis Pain Research

Understanding the Biomechanics of Osteoarthritis Pain

When osteoarthritis (OA) strikes, pain flashes to sensory receptors, unleashing tiny electrical pulses that race up the spinal cord to the brain. Neurons, or specialized nerve cells, release chemical messengers that deliver pain signals from arthritic joints to the sensory network.

Now a new generation of researchers is seeking answers to puzzling questions about osteoarthritis pain. With funding from the Arthritis National Research Foundation, Rachel Miller, PhD, an Assistant Professor in the Department of Internal Medicine at Rush University Medical Center, is investigating how mechanical stimuli trigger osteoarthritis pain.

Osteoarthritis Pain | Rachel Miller, PhD

Chronic pain affects over 100 million Americans and costs the country $500 billion a year in lost productivity. The debilitating pain of OA is a leading cause of disability worldwide. To date, there are no targeted therapies, just non-specific pain medications with potentially dangerous side effects.

Prescription opioids are effective in the short-term, but can lead to addiction and overdose. Aspirin raises the risk of bleeding, while anti-inflammatory drugs like naproxen and ibuprofen can cause liver, kidney and cardiovascular problems. Some OA patients try shots and nerve pain drugs, but still suffer severe and chronic osteoarthritis pain. When it comes to relieving the osteoarthritis pain, there are few good options.

Where does osteoarthritis pain come from? What’s really going on when your knee hurts? What’s the source of the nagging ache in your joints?

 
It’s difficult to design treatments for OA when researchers don’t understand which cell types—and which molecules on those cell types—sense mechanical stimuli and turn it into pain. Dr. Miller is looking at neurons and cartilage cells inside the knee that sense and respond to mechanical stimuli, yet the specific receptors that translate those signals remain unknown.

Although millions of people around the world suffer from osteoarthritis, there are few treatment options beyond total joint replacement. The chronic degenerative disease destroys cartilage and spurs overactive nerves to relay signals to the spinal cord in a cycle of unrelenting pain.

“Despite the fact that pain is the major symptom of osteoarthritis, the sources of pain associated with OA are still understudied,” explains Dr. Miller. “We don’t even know precisely where the nerves that sense pain signals and other types of touch signals are located within the joint. How disease changes nerve pathways also remains unclear.”

In her osteoarthritis research, Dr. Miller is exploring pain mechanisms, including changes in genetic expression and chemical messengers. She hopes to pinpoint how sensory neurons misfire to cause chronic pain.

“Everybody has sensory neurons that respond if you touch a hot stove,” she says. “When you are in chronic pain, just walking around is painful. We want to understand the complex process that occurs when cartilage degrades and signals the nerves to feel pain.”

 
She developed an imaging technique that allows her team to visualize what happens when researchers apply a pinch or a twist to the knee of a genetically modified mouse. “We can watch the neurons fire in real time,” she explains. “The images show that a particular type of neuron responds in OA, but not in a normal mouse.”

The goal is to find ways to directly target pain pathways. “I hope to discover how cells within the knee joint sense and respond to mechanical loading,” says Dr. Miller, who is using her engineering training to study the role of mechanical stimuli. “Understanding how cells respond to mechanical load normally — and how it changes in osteoarthritis — may someday lead to the development of new drugs to treat osteoarthritis.”

Dr. Miller’s reasons for studying osteoarthritis pain are both personal and professional. “A lot of my friends and family members have suffered from OA as they age,” she says. “It’s frustrating to see the decrease in their quality of life,” says Dr. Miller. “Receiving a grant from the ANRF at this early stage in my career is very important, since it helps me to establish myself as an independent researcher and will help to set the stage for future federal grant support as my research expands.”


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CureArthritis
Article Author
Arthritis National Research Foundation
derek@curearthritis.org

The Arthritis National Research Foundation's mission is to provide initial research funding to brilliant, investigative scientists with new ideas to cure arthritis and related autoimmune diseases. Writing articles about the patients affected and the science being done to find a cure shows why we need to come together to #CureArthritis!

1Comment
  • Kathleen Stillwell
    Posted at 17:49h, 19 April Reply

    Dr. Rachael Miller, I am a 60 year old female who has osteoarthritis supported by x-rays of my fingers, upper back, lowerback, knees and feet.. Up until two years ago I have always been extremely active with hiking, biking, swimming, tread-milling, etc. I recently developed pain under my large toe and x-rays are showing I have osteoarthritis in between the seasamoid bones.- on both feet. The right foot hurts for me to even walk on it; it feels like I am stepping on a stone now matter what shoes I am in. I have tried about 50 different pair of running shoes and my feet ache so bad that I can barely walk. I have received cortisone shots, but they have not helped. My father suffered from osteoarthritis from the time he was 79 years old until he died at age 86. My mother suffered from osteoporosis, fracturing many bones and losing 7 ” in height from the age of 50 to 90 when she died. I am very scared and I have always been very physical to relieve emotional stress. I am undergoing emotional stress due to challenges that I face with my 19 year old son. Due to the loss that I feel over both situations I would welcome being involved in any clinical trials that you know of which can cure or lead to a cure of this osteoarthritis. I have also heard of research that Dr. Eveenko is doing in California. If you have any news on his or your studies will you please share them with me. I am in desperate need of your guidance. Thank you so much!

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