Anterior Ankle Impingement

Imaging Gallery

Anterior ankle impingement refers to pain and limited dorsiflexion caused by impingement of structures at the anterior ankle, typically bony spurs and/or hypertrophic soft tissue. It is also known as "footballer's ankle" due to its association with kicking sports.

Epidemiology

• Prevalence: 20-40% of ankle injuries in athletes involve impingement syndromes
• Demographics: Peak incidence in athletes aged 20-35 years
• Sports: Soccer, Australian Rules Football, ballet, basketball, and rugby most commonly affected
• Sex distribution: Male predominance (2:1) reflecting sports participation patterns

Classification (Scranton and McDermott)

Mechanism of Injury

Bony Impingement (Primary):

• Repeated forced dorsiflexion (kicking) causes microtrauma to the anterior capsule and periosteal insertion
• Traction osteophytes develop on the anterior distal tibia and dorsal talar neck
• These "kissing spurs" impinge at end-range dorsiflexion, causing mechanical block and pain
• Direct impaction theory: Repeated ball strikes cause direct trauma to anterior ankle

Soft Tissue Impingement (Secondary):

• Hypertrophic synovium or capsule, particularly after ankle sprains
• Bassett's lesion: Accessory fascicle of AITFL (anterior inferior tibiofibular ligament)
• Meniscoid lesions: Hypertrophic synovial folds trapped in joint
• Scar tissue from previous injury or surgery

Anatomical Considerations

Anterior Tibiotalar Recess:

• The anterior joint line is the most common site of pathology
• Space between tibial plafond and talar dome decreases with dorsiflexion
• Normal clearance of 3-5mm reduces to less than 1mm with maximal dorsiflexion

At-Risk Structures:

• Anterior tibial osteophyte (most common)
• Talar neck osteophyte
• Anterior joint capsule
• Extensor retinaculum
• Deep peroneal nerve and dorsalis pedis artery (surgical consideration)

Pathological Sequence

1. Acute phase: Capsular stretch and periosteal reaction from repetitive microtrauma
2. Inflammatory phase: Synovitis and capsular thickening
3. Proliferative phase: Osteophyte formation at capsular insertions
4. Chronic phase: Established osteophytes with secondary soft tissue changes

History

Athletes, particularly footballers (soccer, Australian rules), present with anterior ankle pain. Pain is worse with activities requiring dorsiflexion: squatting, going uphill, climbing stairs, kicking. There may be a history of previous ankle sprains. Patients note limitation of dorsiflexion compared to the other side.

Examination

Inspection:

• Mild anterior swelling may be visible
• Compare to contralateral ankle
• Note any previous surgical scars

Tenderness: At the anterior joint line, over the anterior tibiotalar joint. Palpate in slight plantarflexion to access anterior structures.

Dorsiflexion Limitation: Reduced compared to contralateral side. Measure with goniometer if available. End-range dorsiflexion reproduces pain.

Impingement Test: Passive forced dorsiflexion reproduces anterior pain. A positive test strongly suggests anterior impingement.

Squeeze Test: Assess syndesmosis by compressing fibula against tibia at mid-calf level. Pain suggests syndesmotic injury rather than pure anterior impingement.

Effusion: May have mild effusion. Palpate anterior recesses.

Exclude Instability: Check for lateral ligament laxity if history of sprains using anterior drawer test and talar tilt.

Imaging Protocol

Plain Radiographs (First-line):

• Lateral weight-bearing: Essential view - shows anterior tibial osteophyte and talar neck spur
• AP mortise view: Assess syndesmosis and joint space
• Oblique views: May reveal lateral osteophytes missed on true lateral
• Limitations: May underestimate spur size as lesions often lateral to midline

CT Scan:

• Indications: Surgical planning, quantify osteophyte size and location
• Better 3D assessment of kissing osteophytes
• Identifies lateral and posteromedial spurs missed on X-ray
• Essential for large Grade III-IV lesions

MRI:

• Indications: Suspected soft tissue impingement, associated pathology
• T2-weighted sequences show synovitis, effusion, bone marrow edema
• Identifies Bassett's lesion (accessory AITFL fascicle)
• Detects meniscoid lesions and capsular thickening
• Evaluates for osteochondral lesions (OCL) of talus

Diagnostic Injection

Technique:

• Fluoroscopic or ultrasound-guided injection
• 2-3ml of local anesthetic (lidocaine/bupivacaine) into anterior recess
• Pain relief confirms diagnosis
• Can combine with steroid for therapeutic effect

Interpretation:

• Greater than 50% pain relief = positive diagnostic test
• Complete relief differentiates from other causes (OCD, arthritis)
• Duration of relief guides prognosis

Differential Diagnosis

Complications of Anterior Ankle Impingement

Untreated Complications:

• Progressive loss of dorsiflexion (functional decline)
• Chronic pain affecting athletic performance and daily activities
• Compensatory gait abnormalities leading to proximal symptoms
• Secondary ankle arthritis from altered joint mechanics

Surgical Complications

General Complications:

• Infection (less than 1% for arthroscopic procedures)
• Deep vein thrombosis (rare in young athletic population)
• Wound healing issues (particularly with open approach)

Procedure-Specific Complications:

Portal-Specific Nerve Anatomy

Anteromedial Portal: Risk to saphenous nerve/vein and medial branch of superficial peroneal nerve

Anterolateral Portal: Risk to superficial peroneal nerve (most common injury)

Risk Factors for Poor Outcome

• Grade IV lesions with secondary arthritis
• Cartilage damage (OCD lesions)
• Significant ankle instability
• Worker's compensation claims
• Prolonged symptoms greater than 2 years pre-surgery

Anterior ankle impingement is particularly common in Australian athletes due to high participation in Australian Rules Football and soccer. The AFL has recognized this as a significant injury pattern, with 2-3% of players affected annually across elite competitions.

Arthroscopic ankle surgery is widely available across Australia, with fellowship-trained foot and ankle surgeons in all major metropolitan centers and increasingly in regional areas. Management follows international best practice with emphasis on conservative treatment first, followed by arthroscopic debridement for recalcitrant cases.

Australian sports medicine guidelines emphasize structured return-to-play protocols following ankle surgery. Most AFL and NRL players follow a graduated rehabilitation program with return to full training at 8-12 weeks and match play by 12-16 weeks. Key clearance criteria include full pain-free dorsiflexion, less than 10% strength deficit, and completion of sport-specific functional testing.

Australian researchers have contributed significantly to understanding and treating anterior ankle impingement, particularly regarding surgical outcomes and return-to-sport protocols in elite football codes.