Clubfoot is a common congenital birth deformity, with a prevalence of 1 in 1000 live births. If left untreated, clubfoot can cause significant disability. Treatment of clubfoot has evolved over several decades and now favors the method of serial casting pioneered by Ignacio Ponseti. This technique involves weekly stretching followed by application of a long leg cast. In the majority of cases, percutaneous tendoachilles lengthening (TAL) is required to correct the equinus component of the clubfoot deformity. Following TAL, a long leg cast is applied for 3 weeks and then a foot-abduction orthosis is utilized to maintain correction of the deformity.

Percutaneous TAL can be performed in the operating room under general anesthesia or in an outpatient setting utilizing local or topical anesthesia. While studies have shown that in-office percutaneous TAL is safe and efficient, little has been done to investigate the pain management strategies implemented for infants during this procedure. Pain management for infants during procedures is important because it has been shown that repeated painful exposures during early stages of life can lead to alterations in hemodynamic stability, altered stress hormone expression, heightened peripheral sensitivity, altered pain reactivity that persists following the painful stimulus, and somatization. One study identified the infant's ability to become conditioned to painful stimuli, such as heel sticks, at as early as 3 days old. Based on this, providers should be prepared to provide adequate pain management for infants during painful procedures, such as in-office TAL, by utilizing non-pharmaceutical techniques, pharmaceutical techniques, or a combination of both.

Needle injection of local anesthetic is generally avoided prior to an in-office percutaneous TAL due to the needle puncture and the concern that soft tissue swelling may prevent accurate palpation of the heel cord during the procedure. As such, topical local anesthetic creams are commonly used to provide local analgesia for this procedure. The cream is applied to the infant's skin around the heel cord and requires 30-60 minutes to provide adequate analgesia, reaching a depth of up to 5 mm at maximum effect. At our institution, a 5 gram tube of L.M.X.4 cream costs $4.12, while other studies report that a larger 25 gram tube of EMLA cream can cost as much as $56, with the excess being wasted. Alternative to anesthetic cream, the J-tip is a needle-free jet injection system that uses compressed CO2 instead of a needle to push 0.25 ml of lidocaine into the skin, providing local analgesia at the site of administration. This method provides analgesia to the site of application at a depth of 5-8 mm and takes approximately 5 minutes to achieve maximum effect. At our institution, the cost of the J-tip applicator and a 20 mL 1% lidocaine vial is $5.11. Multiple studies have demonstrated the J-Tip to provide greater pain control than other pharmaceutical options, including EMLA cream and vapocoolant ("freezy") spray.

The goal of this study is to determine if the J-Tip Xylocaine MPF injection provides equal or greater pain control in clubfoot patients undergoing an in-office percutaneous TAL when compared to L.M.X.4 cream, without an increase in adverse events. If this is true, use of J-tip Xylocaine MPF injection will decrease the overall time and cost of the visit, while ultimately increasing the quality, safety, and value of in-office TAL for the treatment of clubfoot in infants.