The overall goal of this multisite, randomized clinical trial is to evaluate the short- and long-term effectiveness of a Clinical Practice Guideline (CPG)-adherent physical therapy approach to patellofemoral pain (PFP) management among military Service members. The main questions it aims to answer are:

1. Can a CPG-adherent care approach to PFP management improve short- and long-term knee function, pain, and confidence with completing duty-related activities?
2. Can a CPG-adherent care approach to PFP management reduce utilization of healthcare resources and analgesic medication prescription at 12-month follow-up?
3. Are there patient- and care-specific factors that predict or mediate clinical benefit from physical therapy care for PFP?

Researchers will compare the CPG-adherent physical therapy intervention to usual physical therapy care in the Military Health System.

Participants will: 1) be randomized to receive CPG-adherent care or usual care for PFP management; 2) attend physical therapy corresponding to their group assignment; and 3) complete patient-reported outcome measures at baseline and 6-weeks and 3-, 6-, and 12-months post-randomization.

Knee injuries are among the most common musculoskeletal injuries affecting military personnel, accounting for 22% of limited duty profiles and an average of 53 limited duty days per injury in 2017 alone. Patellofemoral pain (PFP) is the most prevalent knee injury affecting Service members but has historically been considered an innocuous and self-limiting condition despite its high rate of persistence. Physical therapy is often the first line-of-defense for PFP management. Published data support the notion that adherence to evidence-based Clinical Practice Guidelines (CPG) improves outcomes 1) for patients, via greater improvements in pain and disability; 2) for providers, by supporting clinical decision making and practice efficiency; and 3) for healthcare systems, by reducing length of treatment, resource utilization, and costs. In 2019, the American Physical Therapy Association (APTA) published its first CPG for PFP management to better enable physical therapists to make evidence-based treatment decisions; however, there is limited evidence regarding the effectiveness of a collective, standardized CPG-adherent approach in clinical care. To evaluate whether patients with PFP who receive CPG-adherent care demonstrate superior outcomes as compared to patients receiving the current usual care, we will compare: (1) CPG-adherent care (intervention arm), wherein physical therapy care is provided according to the CPG "Decision Tree" recommendations for PFP management, to (2) Usual Care (UC; comparator arm), wherein care decisions are made by non-research physical therapists in alignment with current organizational and clinical practice standards in the Military Health System (MHS). This multisite, single-blind randomized controlled trial will include 440 active-duty Service members with PFP across four major MHS physical therapy facilities (i.e., Naval Medical Center San Diego, Naval Hospital Camp Pendleton, Brooke Army Medical Center, and Womack Army Medical Center). The sample will include Service members from the Army, Navy, and Marines, as well as both conventional and special operations forces. The co-primary outcomes include changes in two CPG-recommended outcome measures [Anterior Knee Pain Scale (AKPS) and the Numeric Pain Rating Scale (NPRS)]. Outcomes will be assessed at baseline; 6-weeks post-randomization; and 3-, 6-, and 12-months post-randomization (primary endpoint: 3-months). Secondary outcomes will include between-group differences in confidence with completing duty-related tasks and 12-month analgesic medication prescription and PFP-specific medical resource utilization. An exploratory analysis will seek to determine the predictors and mediators of clinical benefit from physical therapy care for Service members with PFP. Baseline and follow-up assessments will be administered remotely to maximize participant reach and retention. The intervention of interest, CPG-adherent care, is designed to be clinically feasible, with high potential for clinician adoption, which may improve care quality and patient outcomes for Service members with PFP. Long-term, findings from this study have the potential to improve patient care for PFP and other musculoskeletal injury conditions across the MHS by demonstrating the feasibility and positive impact of CPG-adherent care, particularly in terms of improving clinical outcomes and resource utilization and reducing unwanted variability in rehabilitation.

Inclusion Criteria:

• Active-duty Service member
• Aged ≥18 years
• Presence of unilateral or bilateral PFP based on the core criterion of peripatellar and/or retropatellar pain with reproduction of PFP by at least one activity that loads the patellofemoral joint during weight bearing on a flexed knee, such as prolonged sitting, kneeling, squatting, hopping, running, stair climbing, patellar palpation
• Available to participate in physical therapy treatment within 6 weeks of initial enrollment

Exclusion Criteria:

• Presence of tibiofemoral OA based on imaging evidence in the electronic health records in the past year or self-report
• History of patellar or intra-articular knee trauma (e.g., dislocation/fracture) or surgery
• History of neurodegenerative conditions that may affect movement patterns (e.g., Multiple Sclerosis)
• Meniscal or ligamentous pathologies within the past year based on imaging evidence of acute injury in the electronic health record or self-report
• Quadriceps or patellar tendon injuries within the past year based on imaging evidence of acute injury in the electronic health record or self-report
• Known pregnancy (pregnant females may be eligible for participation after end of pregnancy and medical clearance by a qualified and licensed healthcare provider)
• Receipt of physical therapy care for PFP within the three months prior to enrollment
• Known to be pending medical evaluation board, discharge from the military, scheduled deployment, or litigation for an injury at time of enrollment.

The final trial dataset will be made available to the research community upon request to and review by the Leadership Team. Data sharing agreements will be established to document the conditions for research use, privacy and confidentiality standards at the recipient site, and prohibitions for manipulating data for the purposes of identifying individuals. The final trial dataset will include all coded participant data (i.e., data that is de-identified by use of a unique study identification variable, with removal or modification of all identifiers). Individual-level data will include all screening information, baseline measures, intervention information, and primary and secondary outcomes. All SAS datasets will be supplied via secure transfer with the study protocol and data documentation (procedures used to collect the data, details about codes, variable definitions, variable field location, and type of variable).

Datasets will be available no later than the acceptance for publication of the primary and secondary findings from the final data set or one year after database lock.

Given the nature of the CPG-adherent and UC intervention arms, it is not possible to blind treating physical therapists to treatment assignments; however, study participants will be blinded to their group assignments. Research personnel will be trained to endorse clinical equipoise of the two intervention arms during the informed consent process to limit unintentional biases.

Further, all baseline and follow-up assessments will be administered remotely and distributed by a research team member who was not present for the study intervention (i.e., physical therapy treatment), limiting the potential influence of unblinded assessors on the outcomes of the study. Research team members facilitating remote baseline and follow-up assessments will be instructed to not answer or provide any direct guidance regarding completion of patient-reported outcome measures.