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Musculoskeletal and Sports Medicine

Session: Clarifying the patellofemoral pain narrative: improved patellofemoral kinematics and reduced pain following a selective nerve block to the vastus lateralis

Clarifying the Patellofemoral Pain Narrative: Improved Patellofemoral Kinematics and Reduced Pain Following a Selective Nerve Block to the Vastus Lateralis

Thursday, October 23, 2025
12:45 PM - 2:15 PM MT
Location: Original Research Theater

    Co-Author(s)

  • Paige Lind, Other

    IRTA Research Fellow
    National Institute of Health
    Bethesda, Maryland

  • MD

    Matthew Druckenbrod, MD

    Medical Resident
    Medstar Health/Georgetown-National Rehabilitation Hospital PM&R Program
    Arlington, Virginia

  • AM

    Afreen Mushtaheed, Other (she/her/hers)

    Postbacc IRTA Fellow
    National Institutes of Health - Bethesda, MD
    Bethesda, Maryland

    • Primary Author(s)

  • Andrew Roberts, MD

    Resident Physician
    Medstar Health/Georgetown-National Rehabilitation Hospital PM&R Program
    Washington, District of Columbia

    • Co-Author(s)

  • Katharine E. Alter, MD

    Senior Research Clinician
    National Institute of Health
    University Park, Maryland

    • Poster Presenter(s)

  • FS

    Frances Sheehan, PhD

    Senior Research Engineer
    Rehab Medicine, CC, National Institutes of Health
    Bethesda, Maryland

Disclosure(s):
Paige Lind, Other: No financial relationships to disclose
Afreen Mushtaheed, Other: No financial relationships to disclose
Frances Sheehan, PhD: No financial relationships to disclose
Background and/or Objectives: The widely accepted theory regarding idiopathic patellofemoral (PF) pain etiology is that imbalanced muscle forces precipitate a chain reaction of static PF malalignment, dynamic PF maltracking, increased joint contact stresses, and pain. Although the mechanisms of PF pain are not fully understood, lateral overdominance of a weak vastus medialis (VM) is considered a major factor. This study tests the hypothesis that a temporary iatrogenic loss of vastus lateralis (VL) force normalizes (medializes) aberrant patellar kinematics and reduces pain in patients with PF pain.

Design: Experimental Pre-Post Study

Setting : Outpatient Clinic, Research Hospital

Participants : 14 patients with idiopathic PF pain (duration >6 months)

Interventions: Bupivacaine block of the VL (distal third).

Main Outcome Measures: In vivo PF kinematics pre- and post-injection derived from dynamic MRI images. Isometric knee extension strength pre-injection, post-injection, and post-MRI. Functional pain levels assessed using a visual analog scale after completing functional tasks pre-injection, post-injection, and post-MRI.

Results: The temporary block of the distal VL normalized PF kinematics and reduced pain in our patient cohort. Post-injection, the patella consistently (across subjects and knee angles) shifted medially. Patellar tilt less consistently medialized. Patients reported lower pain during exercise and had reduced maximum extensor isometric force capacity both immediately after injection and then after MRI.

Conclusions: This study advances our clinical understanding of PF pain etiology by providing the first direct in vivo evidence supporting the causal link between force alterations, altered PF kinematics, and pain. This study demonstrates the effect of reducing lateral quadriceps force and reinforces the current interventional focus on VM strengthening and the use of a longer acting muscle block (e.g, botulinum toxin) in the VL to medialize PF kinematics and reduce pain. Future studies are planned to evaluate how medializing the patella alters 3D, dynamic, PF joint contact and stress.