Chronic Knee Injury as a Trigger for Depression

Introduction to Chronic Knee Injury and Depression

The American College of Radiology suggests that chronic knee pain affects tens of millions of people annually, often being highly debilitating and negatively impacting the patient's quality of life 1, 2
Psychological disorders such as depression and anxiety are important factors associated with increased pain sensitivity, creating a two-way street where pain causes stress that can trigger or worsen symptoms of depression and anxiety, and vice versa 3, 4
A high rate of patients with chronic pain experience depression and anxiety during their lives, with an elevated risk of suicidal ideation and attempts 3, 5

Chronic pain acts as a potent stressor that can alter bodily homeostasis, activating the hypothalamic-pituitary-adrenal axis, responsible for stress responses 3, 4
This activation directly affects the release levels of glucocorticoids (stress hormones), which play a crucial regulatory role in the immune system 3
Biomarkers such as reduced volume and functionality of the hippocampus and medial prefrontal cortex, observed in some patients with depression and anxiety, have been correlated with blood glucocorticoid concentrations 3, 4

The American College of Radiology recommends that the evaluation of patients with chronic knee pain should include not only imaging exams like radiographs and MRI for diagnosis of the injury but also screening for depressive symptoms 1, 2
Patients with recurrent pain and chronic pain may require psychiatric evaluation and treatment for coexisting anxiety or depression, providing long-term benefits 6

Chronic knee pain can be highly debilitating and frequently negatively impacts the patient's quality of life, with osteoarthritis being the most common cause 1, 2
Patients with chronic pain may require daily pain medication and are at risk of opioid dependence, and should be referred to a pain management specialist for ideal treatment 6
Treatment should address both the physical injury and psychological aspects to maximize outcomes in terms of quality of life 3, 4

Chronic knee pain is associated with the activation of microglia in the central nervous system, which releases inflammatory mediators that contribute to both pain sensitization and the development of depressive symptoms, according to the British Journal of Pharmacology 7, 8
Chronic knee pain can alter gene expression through epigenetic modifications in the prefrontal cortex and amygdala, brain areas involved in mood regulation, as reported in the British Journal of Pharmacology 9

Environmental enrichment (sensory stimuli, physical activity, social interaction, and novelty) can help modulate spinal pathways responsible for the development and maintenance of chronic pain and associated depressive symptoms, as suggested by the British Journal of Pharmacology 10, 11