Central Strap Gastrocnemius Aponeurosis Turn-Down Flap Reconstruction for Chronic Achilles Tendon Ruptures With Large Defects: A Case Series and Frontal Plane 180-Degree Rotation Technique Guide

Abstract Repair of chronic Achilles tendon ruptures presents a significant surgical challenge due to tendon retraction, fibrosis, and degeneration. While isolated flexor hallucis longus (FHL) tendon transfer may provide adequate strength in low-demand patients, higher-demand individuals frequently require a more robust reconstruction that restores continuity of the gastrocnemius-soleus-Achilles complex. The purpose of this study is to describe clinical outcomes following reconstruction of chronic Achilles tendon ruptures with large defects using a central strap gastrocnemius aponeurosis turn-down flap augmented with FHL tendon transfer. Three consecutive patients who underwent Achilles tendon reconstruction using this technique were included. Patients were followed for a minimum of 12 months with evaluation of functional outcomes, plantarflexion strength, and calf circumference measurements. The mean American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score at final follow-up was 93.3. All patients demonstrated 5/5 plantarflexion strength compared to the contralateral extremity. Calf circumference differences between limbs were minimal and did not exceed 1.0 cm in any patient. No re-ruptures or revision surgeries occurred. The central strap gastrocnemius aponeurosis turn-down flap with FHL augmentation represents a reliable option for reconstruction of chronic Achilles tendon ruptures with large tendon defects in higher-demand patients. This technique allows restoration of the posterior muscle-tendon unit using autologous tissue while preserving plantarflexion strength and functional outcomes.