Addressing What Causes Knee Pain
Many people will experience knee pain at some point in their life. However, few are aware of what causes knee pain.
A common source of pain that I see as a Physical Therapist, originates from the patellofemoral joint. This is the joint between the patella and femur (pictured right). A few years ago I read an article by orthopedic surgeon, Scott F. Dye, discussing patellofemoral pain. The article stated why this joint becomes painful as well as which structures in the knee are producing pain.
Dr. Dye’s Findings
Throughout the article Dr. Dye discusses some of the studies he has performed and occasional experiments he did with his own knee. Dr. Dye had a history of patellofemoral pain and a condition called chondromalacia, the softening of the cartilage within the patellofemoral joint.
Dr. Dye underwent a procedure in which various structures of his own knee were probed while he remained conscious. He kept inventory of what structures produced pain during the procedure. The structures that produced the most pain were typically the peri-patellar synovium, which is a membranous lining around the joint. The actual cartilage was not painful to probing, which makes sense, since there does not appear to be any nerve tissue within the cartilage.
Bone Stress & Remedies
Dr. Dye’s studies also looked at bone scans to determine whether people with patellofemoral pain show increased metabolic activity indicative of bone stress. These studies show that the patella and underlying femur do become more stressed in individuals with patellofemoral pain.
Dr. Dye went on to discuss the fine balance of normal bone, as bone is often remodeling and being either broken down or reinforced. Complete bed rest has been shown to lead to weakening of bone while weight-bearing activities, such as walking and other land-based exercises, can promote bone strengthening. This, however, is a balance, as too much activity or trauma can also lead to bone weakening or stress.
What Causes Knee Pain
According research, the leading cause of knee pain is trauma or repetitive stress to the patellofemoral joint. This stress can lead to bone breakdown and inflammation in the joint and its lining, which then causes you pain.
Our goal in physical therapy is to determine what activities are leading to the excessive stress to your patellofemoral joint, as well as possible movement dysfunctions, biomechanical faults, and muscle imbalances that can be addressed to decrease stress. Because bone also requires some level of stress to stimulate growth, we want to appropriately re-introduce stress (exercise) to allow you to get back to the activities you want to do without lingering knee pain.
REFERENCES:
Dye SF. Patellofemoral Pain Current Concents: An Overview. Sports Medicine and Arthroscopy Review. 2001; 9:264-272.