Osteoporotic Fracture and Lidocaine Plaster 5% for Neuropathic Pain preventioN

Preventive Effect of 5% Lidocaine Plaster on the Development of Neuropathic Pain Following Osteoporotic Vertebral Fracture: A Proof-of-concept, Controlled, Randomized Trial

Osteoporotic vertebral fractures may lead to chronic pain with a neuropathic component, which is often underdiagnosed and undertreated in older adults. This proof-of-concept randomized controlled trial aims to evaluate whether early application of a 5% lidocaine plaster can prevent the development of neuropathic pain following an osteoporotic vertebral fracture. Participants will be randomized in a 2:1 ratio to receive either a daily 5% lidocaine plaster plus standard care or standard care alone for 2 months. The primary outcome is the proportion of participants who develop neuropathic pain at 2 months, assessed using the PainDETECT questionnaire.

Osteoporosis is associated with an increased risk of vertebral fractures that may result in persistent pain and impaired quality of life. Beyond nociceptive pain, a substantial proportion of patients develop neuropathic pain after osteoporotic vertebral fractures, which is associated with greater pain severity, sleep disturbances, and functional impairment. Current management often identifies neuropathic pain only after it has become chronic, while systemic treatments may increase the risk of adverse events in older adults.

The FLYNN study is a prospective, randomized, controlled, open-label, proof-of-concept Phase 2 clinical trial designed to evaluate whether early treatment with a 5% lidocaine plaster can prevent the development of neuropathic pain following an osteoporotic vertebral fracture. Participants aged 50 years or older with a vertebral osteoporotic fracture diagnosed within the previous month and pain intensity ≥3 on a numerical rating scale will be randomized in a 2:1 ratio to receive either daily treatment with a 5% lidocaine plaster (12 hours on/12 hours off) plus standard care or standard care alone for 2 months.

The primary endpoint is the occurrence of neuropathic pain 2 months after enrollment, defined by a PainDETECT score ≥19. Secondary outcomes include neuropathic pain assessed by DN4, pain intensity, treatment compliance, adverse events, concomitant medications, sleep quality (PSQI), health-related quality of life (SF-36), and psychophysical pain characterization in participants who develop neuropathic pain.

Inclusion Criteria:

• Male or female participant aged 50 years or older.
• Diagnosis of osteoporosis established by the treating rheumatologist.
• Osteoporotic vertebral fracture diagnosed within the previous month.
• Pain intensity of ≥3 on a numerical rating scale at the fracture site.
• Able and willing to provide written informed consent.
• Affiliated with a French health insurance system.

Exclusion Criteria:

• Medical or surgical condition considered by the investigator to be incompatible with study participation.
• Known hypersensitivity to lidocaine, any excipient of the study treatment, or other amide-type local anesthetics.
• Current treatment with Class I antiarrhythmic agents (e.g., tocainide, mexiletine) or other local anesthetics.
• Inflamed or damaged skin at the intended application site (e.g., active herpes zoster lesions, dermatitis, or wounds).
• Pregnant or breastfeeding women.
• Women of childbearing potential not using an effective contraceptive method.
• Positive urine pregnancy test for women whose menopausal status cannot be confirmed.
• Participation in another clinical research study.
• Individuals under legal protection or deprived of liberty.
• Refusal to participate.