Infants undergoing Ponseti treatment for idiopathic clubfoot often require percutaneous tendoachilles lengthening (TAL) after serial casting. This procedure is frequently performed in the office with a local anesthetic to avoid exposure to general anesthesia in the operating room. Topical anesthetic creams are commonly used to provide local analgesia for this procedure. The cream is applied to the infant's skin around the achilles tendon and requires 30 minutes to provide adequate analgesia, reaching a depth of up to 5 mm at maximum effect. An alternative is a needle-free jet injection system that uses compressed CO2 to push 0.25 ml of lidocaine into the skin, providing local analgesia at the site of administration. This method likewise provides analgesia to the site of application at a depth of 5-8 mm, yet only takes approximately 1-2 minutes to achieve maximum effect.

Aim 1: Determine which pain management method, topical anesthetic cream (4% liposomal lidocaine) vs. jet infection of local anesthesia (1% lidocaine), provides the greatest pain relief to infants with clubfoot undergoing an in-office percutaneous TAL.

Hypothesis: Jet injection will provide equal or greater pain control when compared topical anesthetic cream.

Aim 2: Determine if there is a difference in the rate of adverse events between the two pain management methods, topical anesthetic cream (4% liposomal lidocaine) vs. jet infection of local anesthesia (1% lidocaine).

Hypothesis: Jet injection of local anesthesia will not be associated with an increased rate of adverse events in comparison to topical anesthetic cream.

If jet injection of local anesthesia is shown to provide comparable or better pain control without an increase in adverse events, use of this needle-free injection system will decrease the overall length of the procedure visit, thus increasing quality, safety, and value.

Clubfoot is a common congenital birth deformity, with a prevalence of approximately 1 in 1000 live births. Without treatment, clubfoot can cause significant disability. Percutaneous tendoachilles lengthening (TAL) is commonly required to correct residual equinus deformity during the Ponseti method. TAL may be performed in the operating room under general anesthesia or in outpatient settings using local anesthesia, but evidence guiding optimal anesthetic strategies for in office procedures remains limited.

Effective pain control in infancy is critical. Experimental and clinical studies demonstrate that repeated early life painful stimuli lead to hyperinnervation, heightened sensitivity, altered stress responses, and lower pain thresholds later in life. Cumulative procedural pain is associated with poorer cognitive and developmental outcomes and early interventions to reduce pain lessen cortisol exposure and improve neurobehavioral trajectories. Poorly controlled pain during neonatal or early childhood procedures has also been linked to altered pain behaviors during later procedures, emphasizing the long lasting impact of early nociceptive experiences.

Existing approaches for in office TAL include needle infiltration of local anesthetic or application of topical anesthetic cream. Needle infiltration may create soft tissue swelling that obscures the tenotomy site and increases procedural difficulty, and both techniques have been associated with substantial infant distress despite adequate application.

Needle free jet injection offers a potential alternative. Prior studies demonstrate that jet injection produces less pain than conventional needle infiltration and provides superior analgesia to topical anesthetics for procedures such as venipuncture, intravenous catheter placement, and lumbar puncture.

The Clubfoot Tenotomy Trial (ClubTT) was designed to evaluate whether jet injected local anesthesia provides equivalent analgesic efficacy without increasing adverse events compared with topical anesthesia for infants with idiopathic clubfoot undergoing in office TAL.

Inclusion Criteria

• Clubfoot patients less than 6 weeks of age at start of casting
• Patients requiring in-office percutaneous achilles lengthening (TAL) following serial casting

Exclusion Criteria

• Clubfoot patients greater than 6 weeks of age at the start of casting
• Previous clubfoot treatment
• Patients with a neuromuscular condition (spina bifida, caudal regression syndrome, arthrogryposis, etc.)
• In-office TAL is not recommended by treating physician

There is not currently a plan to share IPD with other researchers.

Adverse event data was collected starting at enrollment and continued up to the final study visit, up to 3 weeks.

A principal limitation is that infants cannot directly report pain during the tenotomy, requiring reliance on surrogate markers-such as heart rate, oxygen saturation, and FLACC behavioral scores-to estimate pain severity. Additionally, individual variability in responses to painful stimuli may not be fully captured by temperament assessments or baseline surrogate measures.

On the day of or after the final casting visit, the participant will be randomized in equal proportion (1:1) to either the control group (4% liposomal lidocaine cream with saline jet injection) or the intervention group (placebo cream with 1% lidocaine jet injection). Participants, care providers, investigators, and outcome assessors will be blinded to the randomization groups.

An outside pharmacy, the Health & Wellness Compounding Pharmacy, will provide and blind the 4% liposomal lidocaine and placebo creams. The Vanderbilt Investigational Drug Service will provide the blinded 1% lidocaine and saline vials for jet injection. The Investigational Drug Service will store the creams provided by the outside pharmacy and the jet injection vials. They will assist in dispensing the creams/vials to the outpatient clinic.