This study aims to assess the distance between the Achilles tendon and nearby neurovascular bundles bilaterally in infants with unilateral clubfoot deformity using ultrasound (US)- Doppler at 1 cm and 2 cm above the calcaneal tuberosity.

Idiopathic clubfoot is a congenital deformity affecting the musculoskeletal structure of the foot .The Ponseti method remains the gold standard for its correction, culminating with a percutaneous Achilles tenotomy (1). Treatment of clubfoot with the Ponseti method has improved anatomical and functional results and reduced the number of surgical interventions required (4,7). In 80-90% of cases, a percutaneous tenotomy of the Achilles tendon is needed at 3-4 months of age, if the equinus position of the foot persists after corrective casts, and if the dorsiflexion of the ankle is less than 10º (7). The surgery is often performed as an outpatient procedure under local anesthesia and seems to be low risk. However, a complication rate of up to 4 % has been recorded , and the complications include pseudoaneurysm, necrosis, or gangrene of the foot that underwent intervention (7). The safety of this procedure critically depends on the spatial relationship between the Achilles tendon and adjacent neurovascular structures (6). Our objective is to study the use of ultrasound (US)- Doppler before Achilles tendon tenotomy bilaterally to determine the distance between the tendon and the posterior tibial neurovascular bundle in infants with unilateral clubfoot .

Inclusion Criteria:

• Infants aged 1-6 months
• Unilateral clubfoot deformity and a normal opposite foot

Exclusion Criteria:

• Non-idiopathic or syndromic clubfoot
• Previous foot surgery , contralateral foot deformity

Thestudy population will consist of infants aged 1 to 12 months diagnosed with unilateral idiopathic clubfoot who present to the Orthopedic and Trauma Surgery Department at Assiut University Hospitals. Each participant will have one affected (clubfoot) limb and one normal contralateral foot, allowing for within-subject comparative measurements.

Only infants with idiopathic, non-syndromic clubfoot deformity will be included to ensure homogeneity of the study group. Participants must have no history of previous foot surgery, no contralateral deformities, and no contraindications to ultrasound assessment.

Parents or legal guardians of eligible infants will receive a full explanation of the study purpose and procedures prior to enrollment. Participation will be voluntary and based on written informed consent.

A total sample of 40 infants (40 affected feet and 40 contralateral normal feet) will be recruited as a pilot population for measurement and comparison of Achilles tendon-neurovascula