Association of Physical Therapy Care With Use of Intra-Articular Injections in People With Knee Osteoarthritis: A Real-World Cohort Study

Objective

The objective of this study was to assess the relation of physical therapy (PT) timing, dose, and type with risk of future intra-articular therapy use in people with knee osteoarthritis (OA) who receive PT.

Methods

We used data from a deidentified claims database (Optum Labs Data Warehouse) from American adults with incident knee OA referred for PT within the first year of their knee OA diagnosis. We categorized people as having previously had intra-articular therapies or not. We examined the association of timing of PT initiation, number of PT sessions, and type of PT (predominantly active or passive) with intra-articular therapy use over a period of one year following the first year of diagnosis.

Results

Of the 67,245 individuals with knee OA (age 61.5 ± 11 years, 61% female, 10% Black, 6% Hispanic), 34,804 and 32,441 did and did not have prior intra-articular therapies, respectively. Among those who had prior intra-articular therapies, initiating PT at 9 to 12 months post diagnosis was associated with an adjusted risk ratio of 1.44 for future intra-articular therapy (95% confidence interval 1.35–1.55) compared with those who initiated within a month. For both groups, ≥13 PT sessions was associated with a 10% and 12% lower risk, respectively, compared with 1 to 5 sessions. Active PT was not related to lower risk compared to passive PT interventions.

Conclusion

Initiating PT earlier and more than 12 PT sessions were significantly associated with lower risk of future intra-articular therapy use in people with newly diagnosed knee OA.