Bilateral Chronic Achilles Tendon Rupture Treated With FHL Tendon Transfer: A Case Report

Medical professionals are documenting specialized surgical interventions to treat chronic bilateral Achilles tendon ruptures, a condition described as very rare and particularly difficult to manage due to the physical changes that occur in the tendons over time.

While individual Achilles tendon ruptures are a common injury, the occurrence of ruptures in both legs is uncommon. The challenge increases when these ruptures become chronic, as the tendons often undergo retraction and atrophy, making standard repair techniques less viable.

The Challenge of Chronic Bilateral Ruptures

In chronic cases, the gap between the ruptured ends of the tendon typically increases. According to a case report published in Medicine (Baltimore) on August 28, 2020, the treatment of these injuries is very challenging due tendon retraction and atrophied.

Because the original tendon tissue may no longer be suitable for a direct primary repair, surgeons often turn to tendon transfer procedures. These procedures involve rerouting a functioning nearby tendon to take over the role of the damaged Achilles tendon, thereby restoring the patient’s ability to plantarflex the foot.

Surgical Approaches Using FHL Transfer

One primary method for reconstruction involves the flexor hallucis longus (FHL) tendon. Recent reports highlight different surgical strategies for implementing this transfer depending on whether the ruptures occurred simultaneously or asynchronously.

For patients with bilateral asynchronous ruptures, surgeons have utilized a modified minimally invasive whole FHL tendon transfer to repair the defects. This approach aims to bridge the gap created by the retracted tendon while minimizing the surgical footprint.

In cases of bilateral simultaneous chronic ruptures, other techniques have been employed. A case report from Cureus describes the use of both open and endoscopic FHL tendon transfers to address the simultaneous injuries in both legs.

Alternative Reconstruction with FDL Transfer

Beyond the FHL tendon, the flexor digitorum longus (FDL) tendon provides another option for reconstruction. This represents particularly useful in complex chronic cases where additional structural support is needed.

A case report published on January 23, 2026, in the Journal of Clinical Medicine (J Clin Med) detailed a simultaneous bilateral reconstruction that combined two specific techniques:

• The transfer of the flexor digitorum longus (FDL) tendon.
• The use of turndown flaps to assist in the reconstruction process.

Comparing Tendon Transfer Strategies

The choice between FHL and FDL transfers, as well as the choice between open, endoscopic, or minimally invasive techniques, depends on the specific clinical presentation of the patient. The primary goal across all these methods is to overcome the limitations imposed by the chronic nature of the injury, specifically the retraction of the tendon ends.

The documented cases suggest that both FHL and FDL transfers are viable options for restoring function in patients who have suffered rare bilateral chronic ruptures. By utilizing these donor tendons, surgeons can effectively bypass the atrophied sections of the Achilles tendon and provide the necessary tension to restore mobility to the ankle joint.