Reduction in Thigh Muscle Strength Occurs Concurrently but Does Not Seem to Precede Incident Knee Pain in Women: Data From the Osteoarthritis Initiative Cohort.

This is an observational cohort. It cannot prove that thigh muscle strength loss caused incident knee pain or that pain caused strength loss. Strength was measured only every 2 years. The exact timing of strength change relative to pain onset is unknown. Pain could have begun early in the 2-year interval. The prior and concurrent windows are therefore approximate. Only 5 participants had a WOMAC knee pain score of 10 or more at year 4. Pain at the final visit could still have limited maximal strength effort. The healthy reference cohort could not be compared for longitudinal strength. Only 3 had strength measurements at year 4. Only one knee per participant was analysed. When both knees qualified, selection rules chose the more painful or right knee. The incident pain definition required pain to persist for at least one more year. Brief episodes were not counted as incident pain. Knees without complete age, body mass, BMI, pain, radiographic grade, or strength data were excluded. This may limit generalisability. Analyses were split by sex and radiographic status. Findings apply to those subgroups rather than all people with knee pain.

No conflicts of interest statement is provided in the supplied text. The article is listed as supported by NIH extramural and non-U.S. government funding.

Do not conclude that thigh muscle strengthening prevents knee pain. The study did not show strength loss before new knee pain. In women with radiographic knee OA, strength loss occurred concurrently with pain. Strength at the last pain-free visit did not separate cases from controls.