Achilles Tendon Injuries

The Achilles tendon is the largest and strongest tendon in the body — and the most frequently injured. While Achilles tendinitis describes the acute inflammatory presentation most common in active adults with overuse, the broader spectrum of Achilles tendon pathology includes chronic tendinosis and acute rupture, each representing a distinct clinical entity requiring different evaluation and management.

Achilles tendinosis is the degenerative form of the condition — where the normal collagen architecture of the tendon has been replaced by disorganized, weaker fibers through a process of failed tendon healing. Unlike tendinitis, tendinosis is not primarily inflammatory. The tendon is intrinsically weakened, often thickened and irregular on imaging, and at increased risk of partial or complete rupture under load. Tendinosis does not respond to anti-inflammatory treatment because inflammation is not its primary pathology — it responds to loading-based rehabilitation designed to stimulate tendon remodeling. A tendon in the degenerative tendinosis state can rupture with less force than a healthy tendon would require.

Achilles tendon rupture — partial or complete — is one of the most serious athletic foot and ankle injuries. Complete rupture typically occurs during a sudden explosive eccentric load: a jump, a sprint start, a forceful push-off. Patients classically describe feeling or hearing a pop at the back of the ankle, followed by sudden severe pain and inability to push off the foot or stand on tiptoe. The injury is frequently mistaken for a severe ankle sprain in the immediate aftermath. The Thompson squeeze test — squeezing the calf produces no foot plantarflexion in a complete rupture — is a reliable bedside diagnostic finding.

Partial Achilles ruptures present with similar but less dramatic symptoms — significant posterior heel pain, often with a palpable defect or thickening in the tendon, without the complete loss of plantarflexion strength seen in complete rupture. MRI is the most reliable imaging modality for distinguishing partial from complete rupture and assessing the extent of tendon involvement.

Dr. Gunter evaluates Achilles injuries clinically and with imaging when indicated, distinguishes between tendinitis, tendinosis, partial rupture, and complete rupture, and develops a management plan appropriate to the specific diagnosis. For complete ruptures, he discusses both surgical and non-surgical management options honestly — the evidence supports both approaches in appropriate patients, and the decision is individualized.