Ankle Impingement

Anterior ankle impingement: patients describe anterior ankle pain worse with dorsiflexion (stairs, squatting, running uphill, kicking, lunging), restricted dorsiflexion, a catching or pinching sensation, and anterior ankle swelling after activity. Examination shows anterior joint line tenderness over the tibial margin or talar neck and reduced dorsiflexion compared with the contralateral side. Distinguish a bony block (hard end-feel that stretching will not improve) from soft tissue restriction or calf tightness (stretching may improve it) - this distinction is clinically important. The anterior impingement test (palpate the anterior joint line while passively dorsiflexing) reproduces pain localised to the anterior joint line.

Anterolateral soft tissue impingement: persistent anterolateral pain after a lateral ankle sprain that has otherwise healed. Anterolateral gutter tenderness (between lateral malleolus and talar dome, anterior to the fibula), positive anterior impingement test with anterolateral pain on forced dorsiflexion, and stable ligaments on stress testing (if instability coexists, both should be addressed). X-rays are often normal; MRI demonstrates the soft tissue pathology.

Posterior ankle impingement: posterior ankle pain worse with plantarflexion (going en pointe, shooting, walking downhill, push-off). FHL symptoms (pain with great toe flexion or extension, triggering or catching of the great toe) suggest FHL involvement. Often in dancers, footballers, and cricket fast bowlers. Examination shows posterior ankle tenderness deep to the Achilles at the level of the posterior talar process. The posterior impingement test (passively force maximal plantarflexion) reproduces posterior pain - the most useful manoeuvre. Assess FHL by resisted and passive great toe flexion or extension in slight plantarflexion. Always exclude Achilles tendinopathy or rupture, retrocalcaneal bursitis, and peroneal pathology.

Red flags: acute posterior pain after forced plantarflexion (os trigonum or Stieda process fracture); acute posterior calf or ankle pain with loss of push-off (Achilles rupture - perform Simmonds-Thompson); deep posterior calf or ankle pain with VTE risk factors (consider DVT); progressive dorsiflexion loss with joint space narrowing (suggests ankle OA); night pain, weight loss, systemic features (bone tumour or infection); hot swollen ankle (exclude septic arthritis and crystal arthropathy).

Ankle impingement can often be diagnosed clinically. Initial treatment is usually non-operative before imaging or surgery is considered.

Plain radiographs (AP, lateral, mortise views): the lateral view is most useful for anterior osteophytes; an AMI (Anterior Margin Impingement) view can demonstrate anteromedial osteophytes that the standard lateral may miss. For posterior impingement the lateral view shows an os trigonum or elongated Stieda process. Weight-bearing views assess joint space.

CT provides detailed bony characterisation and pre-operative planning.

MRI is often the most informative test for soft tissue impingement, demonstrating anterolateral gutter soft tissue, FHL tenosynovitis, bone marrow oedema in an os trigonum, osteochondral lesions, and cartilage status. It is particularly important for anterolateral soft tissue impingement where X-rays are typically normal.

USS demonstrates anterior osteophytes, effusion, synovitis, anterolateral gutter soft tissue, and FHL tenosynovitis. Dynamic assessment during dorsiflexion or plantarflexion can visualise impingement in real time. It can guide injection. Operator-dependent.

Diagnostic local anaesthetic injection (often USS-guided) is a useful adjunct - if it completely relieves pain during the provocative movement, this strongly supports the impingement as the pain source and can predict surgical outcome. Combining with corticosteroid provides both diagnostic confirmation and therapeutic relief.

Conservative management is first-line. Surgical management (usually arthroscopic or endoscopic) is considered when conservative measures fail.

Conservative management:

• •Activity modification to reduce the provocative movement
• •Footwear modification: anterior impingement - a small 1 to 2 cm heel raise reduces dorsiflexion demand; rocker-bottom shoes. Posterior impingement - avoid footwear that forces plantarflexion
• •Taping and bracing to limit end-range dorsiflexion or plantarflexion during sport
• •Topical or oral NSAIDs for short-term relief; paracetamol for pain
• •USS-guided corticosteroid injection into the anterior joint, anterolateral gutter, or around the os trigonum provides short-to-medium-term relief and is also diagnostically useful

Surgical management when conservative care fails:

• •Anterior ankle impingement: arthroscopic debridement of osteophytes and excision of hypertrophied soft tissue. Generally good outcomes when joint space is preserved (isolated impingement); if significant OA is present (global joint space narrowing) debridement provides only temporary relief. This distinction is the most important prognostic factor. Complications include superficial peroneal nerve injury from the anterolateral portal, infection, and recurrence
• •Anterolateral soft tissue impingement: arthroscopic excision of scar tissue, hypertrophied synovium, meniscoid lesions, and thickened bands. If chronic instability coexists it must also be addressed (e.g. Brostrom procedure)
• •Posterior ankle impingement: hindfoot endoscopy is the standard. Os trigonum or Stieda process is excised along with inflamed tissue, and FHL release can be performed simultaneously when needed. Good outcomes. Complications include sural nerve injury from the posterolateral portal, infection, and FHL injury

Refer to an orthopaedic foot and ankle specialist if conservative care fails, symptoms significantly limit sport or daily function, diagnostic uncertainty persists, or surgical debridement is being considered.

Conservative rehabilitation:

• •Phase 1 (symptom modification): activity modification, footwear modification (heel raise for anterior impingement), taping, short-course analgesia. Consider USS-guided corticosteroid injection for diagnostic and therapeutic purposes
• •Phase 2 (restore function): maintain ankle range while avoiding the impingement range. Calf stretching may improve dorsiflexion when soft tissue tightness contributes, but it will not overcome a true bony block (hard end-feel from an osteophyte). Strengthen calf, peroneals, tibialis anterior, and intrinsic foot muscles. Proprioception and balance training
• •Phase 3 (return to sport): graduated return to provocative activity with monitoring. Technique modification (kicking, landing). Taping or bracing during sport. Ongoing strengthening and proprioception

Post-arthroscopic anterior debridement: 0 to 2 weeks wound care, compression, weight-bearing as tolerated, early range of motion - the priority is to use the freed dorsiflexion before scar tissue restricts it. 2 to 6 weeks progressive weight-bearing, strengthening, calf stretching, proprioception. 6 to 12 weeks progressive functional activity, jogging, sport-specific training. Key principle: regain dorsiflexion early.

Post-hindfoot endoscopy (posterior os trigonum excision): 0 to 2 weeks wound care, weight-bearing as tolerated, early ankle range of motion (and great toe motion if FHL was released). 2 to 6 weeks progressive strengthening, calf raises, balance. 6 to 12 weeks return to sport. For ballet dancers, progressive return to pointe work. Recovery is generally faster than for anterior debridement.

• •van Dijk et al. (KSSTA 1997) - established the modern classification and posterior endoscopic technique for posterior ankle impingement, particularly in dancers.
• •van Dijk (Foot Ankle Clin 2006) - landmark review of anterior ankle impingement; preserved joint space predicts good arthroscopic debridement outcomes, while global narrowing (OA) predicts only temporary relief.
• •Bassett et al. (JBJS-Am 1990) - described the accessory AITFL fascicle (Bassett ligament) as a contributor to anterolateral soft tissue impingement after lateral ankle sprain.
• •BOFAS UK consensus - hindfoot endoscopy is the established procedure for posterior impingement; arthroscopic debridement is standard for anterior and anterolateral impingement.
• •BJSM consensus on lateral ankle sprain rehabilitation - inadequate rehabilitation after lateral ankle sprain predicts persistent anterolateral impingement and chronic instability.

• •Anterior impingement = pain on DORSIFLEXION (footballer's ankle). Posterior impingement = pain on PLANTARFLEXION (dancer's ankle). Anterolateral soft tissue impingement is the commonest cause of persistent anterolateral pain after a lateral ankle sprain.
• •Os trigonum is a common normal variant (7 to 14 percent). Only clinically relevant when symptoms and examination fit posterior impingement.
• •FHL tenosynovitis commonly coexists with posterior impingement, particularly in dancers; FHL triggering of the great toe is a specific symptom.
• •Anterior osteophytes may indicate early OA or isolated impingement. Preserved joint space predicts good arthroscopic outcomes; global narrowing (OA) predicts only temporary relief.
• •Bassett ligament (accessory AITFL fascicle) is a recognised contributor to anterolateral impingement; X-rays are typically normal, so MRI is required.
• •Superficial peroneal nerve is at risk from anterolateral arthroscopic portals; sural nerve is at risk from posterolateral endoscopic portals. After arthroscopic debridement, regain freed dorsiflexion or plantarflexion early before scar tissue restricts it.