What Is Posterior Ankle Impingement — The Back-of-Ankle Pain Problem

Posterior ankle impingement is compression of soft tissue or bone at the back of the ankle during forced plantarflexion (pointing the foot downward) — the impingement occurs between the posterior tibia and calcaneus when they are forced together. The condition has two forms: soft tissue impingement (synovitis and fibrosis of the posterior joint capsule, without a bony accessory bone) and os trigonum syndrome (impingement of an os trigonum — a small accessory bone present in approximately 10% of the population as a separate ossification center posterior to the talus). The classic athletic presentations: ballet dancers performing en pointe or demi-pointe who compress the posterior ankle with every relevé; soccer players who repetitively kick with the instep (plantarflexion-loaded kicking); and gymnasts in tumbling and vault dismounts. The pain is sharp, posterior, and specifically provoked by forced plantarflexion — the forced plantarflexion test reproduces it immediately. At Balance Foot & Ankle in Howell and Bloomfield Hills, Michigan, Dr. Tom Biernacki, DPM diagnoses and treats posterior impingement accurately. Call (810) 206-1402.

Os Trigonum — Normal Variant vs. Symptomatic Impingement

The os trigonum is present in approximately 10% of the population bilaterally and is asymptomatic in most individuals — it only becomes a clinical problem when the sport or activity demands forced plantarflexion that compresses the os trigonum between the posterior talus and calcaneus. The distinction: incidental os trigonum (common, found on X-ray, no symptoms) vs. symptomatic os trigonum (same X-ray finding but with posterior ankle pain that is reproduced by the forced plantarflexion test and pressure over the os trigonum itself). MRI confirms symptomatic os trigonum by showing bone marrow edema within the os trigonum, synovitis in the posterior recess, and FHL (flexor hallucis longus) tendon irritation — all signs of active impingement. The os trigonum can also be acutely fractured — an avulsion from sudden forced plantarflexion — producing immediate severe posterior ankle pain identical to a lateral ankle sprain but at the posterior aspect.

Conservative Management — Activity Modification and Injection

Conservative management of posterior ankle impingement: activity modification — elimination of forced plantarflexion activities during the acute phase; for ballet dancers, temporary restriction to flat work without pointe; for soccer players, temporary modification to non-kicking activities; corticosteroid injection into the posterior ankle recess — reduces synovitis and provides 3–6 months of pain reduction in approximately 60% of patients; and FHL tendon stretching — the flexor hallucis longus runs through the posterior ankle and often has adhesions at the posterior impingement site; stretching reduces the FHL contribution to impingement symptoms. Conservative management succeeds in approximately 50–60% of posterior impingement cases — the remaining cases require surgical intervention when the sport demands cannot be accommodated by activity modification.

Surgical Treatment — Os Trigonum Excision

Os trigonum excision — removal of the os trigonum through a posterior ankle arthroscopic or open approach — is the definitive treatment for symptomatic os trigonum that has failed conservative management. Arthroscopic posterior ankle surgery provides direct visualization of the posterior recess, removal of the os trigonum, debridement of the posterior capsule synovitis, and simultaneous FHL tendon release when indicated — through two small posterior portals. Recovery: non-weight-bearing 2–3 weeks, progressive weight-bearing 4–6 weeks, return to dance or sport at 3–4 months. Outcomes for ballet dancers: 80–90% return to pointe work at 3–4 months post-operatively. The os trigonum excision is one of the highest success-rate procedures in sports foot and ankle surgery when patient selection is appropriate.

Posterior Ankle Impingement Treatment in Howell & Bloomfield Hills Michigan

Dr. Tom Biernacki, DPM performs the forced plantarflexion test and posterior ankle palpation for impingement evaluation, coordinates MRI for os trigonum and posterior synovitis assessment, and provides posterior ankle injection and sport-specific activity modification at Balance Foot & Ankle. Ballet dancers, soccer players, and gymnasts with posterior ankle pain should be evaluated before continuing plantarflexion-demand activities. Serving Howell, Brighton, Novi, Bloomfield Hills, and all Southeast Michigan. Book your evaluation or call (810) 206-1402.

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Dr. Tom Biernacki, DPM

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Dr. Tom Biernacki, DPM

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.