High number of pain sites predicted poor outcomes, change in patellofemoral pain
A higher number of pain sites throughout the body in patients with patellofemoral pain was predictive of poor outcomes and less change 1 year after treatment, according to study results.
Researchers identified 112 patients aged 16 to 40 years old with a minimum 3-month history of patellofemoral pain and had 1 year of follow-up. During 6 weeks of intervention, 39 patients were assigned to patient education combined with isolated hip exercise; 37 patients had patient education with traditional knee-based exercise; and 36 patients had patient education and free training. At 1 year, investigators evaluated the predictive ability of sex, bilateral pain, worst pain, pain duration, anterior knee pain scale (AKPS), kinesiophobia, anxiety and depression, self-efficacy and number of pain sites throughout the body on AKPS and worst pain. They also evaluated the global change score, change in AKPS and change in worst pain at 1 year. Predictors of poor outcome were determined with multivariable linear regression models with stepwise backward removal method.
Results showed that at 1 year, the number of pain sites at baseline significantly predicted worst outcomes for AKPS, worst pain, global change, change in AKPS and change in worst pain. Baseline AKPS and worst pain scores predicted respective 1-year level and change scores. Less global change was predicted with lower self-efficacy and male sex. Longer pain duration was a predictor for final score and change score for worst pain. “The predictive models had reasonable fit with adjusted R2 from 0.22 to 0.35,” the researchers wrote. – by Monica Jaramillo
Disclosure: This study was funded by the Research Department of Sørlandet Hospital.
Perspective
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As clinicians, we are not only in search of optimal treatments for our patients, but also are in search of patient-specific factors that will influence the patient response to treatment. Hott and colleagues published such prognostic factors in patellofemoral pain in their study, “Predictors of pain, function, and change in patellofemoral pain,” published in AJSM in 2019. Psychologic factors have been found to have a profound effect on patient outcomes in diverse fields as arthroplasty, ACL surgery and back pain and thus, it is no surprise to see a similar effect when treating patellofemoral pain.
Pain is the central perception of a peripheral nociceptive signal. While the nociceptive signal may be triggered by similar pathologies in two patients, ultimately their central processing is the key to their perception of pain. Treating these two patients with the same peripheral (patellofemoral) approach is likely to produce differing outcomes. Understanding who will and who won’t respond to treatment may allow a more in-depth discussion at the onset of treatment to assure expectations are realistic.
Most physicians who have practiced more than a few years have developed a “sixth sense” as to which patients will respond to treatment. Studies in arthroplasty and back pain have shown that patients with depression, pain amplification/catastrophic thinking and poor outlook on life in general do worse than those without depression, who have a graded response to nociceptive stimuli and have a positive outlook on life.
Hott and colleagues compared two patellofemoral pain groups treated with an education and exercise-based intervention. They found that the most consistent predictor of pain, function and patient-reported outcome changes at 1 year was the number of pain sites in the patient’s body, as well as longer pain duration and lower self-efficacy. This study further supports a wholistic approach when treating the patellofemoral pain patient as in certain patients, this could even mean enlisting the aid of psychological experts.
OrthoIndy Center for Joint Preservation, Cartilage Regeneration and OrthoBiologics/Regenerative Medicine
Patellofemoral subsection
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