What is posterior ankle impingement?
Understanding Posterior Ankle Impingement (PAI): What You Need to Know
Posterior Ankle Impingement (PAI) is a condition where bone or soft tissue becomes pinched at the back of the ankle—specifically between the tibia/fibula and the talus. It often worsens with plantar flexion (pointing the toes), whether under load (e.g., standing on tiptoe) or not.
What Causes PAI?
There are two primary causes:
Overuse – Common in athletes and dancers, where repetitive strain leads to irritation and inflammation of soft tissues.
Trauma – Often linked to ankle sprains or blunt force, which may lead to acute or chronic changes in joint mechanics.
Traditionally, PAI was attributed to structural abnormalities like an Os Trigonum (a small extra bone) or overgrowth from the talus (Steida’s process). However, new research shows that these bony abnormalities don’t always correlate with pain—many people have them without symptoms. This shifts the focus toward soft tissue involvement and biomechanical issues.
Who’s at Risk?
Athletes in high-impact or high-flexibility sports are most at risk:
Ballet dancers
Runners
Jumping athletes (e.g., basketball, netball)
Kicking sports (soccer)
A sudden increase in training load or intensity can cause inflammation in the posterior capsule or tendons, especially with repetitive end-range plantar flexion.
Soft Tissue and PAI
Chronic ankle instability from poorly rehabbed sprains can cause abnormal talus movement, impinging on soft tissues. Over time, this leads to tissue thickening and persistent pain. The flexor hallucis longus (FHL) tendon is particularly vulnerable, especially in activities involving toe push-off like ballet.
Recognizing the Symptoms
Patients typically describe:
Deep, hard-to-locate pain in the back of the ankle
Sharp, dull, or radiating discomfort
Pain triggered by going on tiptoe, pointing the foot, jumping, or downhill walking
No associated nerve-related (radicular) symptoms
Common Misdiagnoses
PAI is frequently mistaken for:
Achilles tendinopathy
Peroneal or tibialis posterior injuries
Tarsal tunnel syndrome
Osteoarthritis of the talus
FHL tendinopathy
Sural nerve issues
Lumbar radiculopathy
Treatment
Treatment will commonly include a combination of manual care and active rehab. Each treatment is specific to the individual injury and associated findings. Options may include;
Dry needling the associated impingement tissue
Graston/ Soft tissue therapy
Joint adjustments or mobilisation
Flossing band for fascial release
Rehab including joint opening (banded)
Rehab and strength to posterior chain (avoiding full plantar flexion)
Intrinsic foot balance and stability
Final Thoughts
Accurate diagnosis of PAI is crucial to avoid mistreatment. Understanding its true causes—beyond just bony impingement—allows for better, more targeted rehab strategies. If you experience persistent rear-ankle pain, especially with activities involving plantar flexion, consider PAI as a possible culprit.
