Ankle Impingement

Ankle impingement can be classified as anterior, posterior, medial, or lateral.

Anterior Ankle Impingement

Most Common Causes

  1. Soft tissue impingement – Capsular synovitis blocking dorsiflexion.
  2. Talar or tibial spurs – Within the capsule (on tibia), impinging in dorsiflexion.
  3. AITFL Inferior Tear – Forms a meniscal-type loose fragment that impinges.

Clinical Features

  • Pain over anterior joint line and on dorsiflexion.
  • Usually a history of injury or impact sports participation.
  • Molloy-Bendall impingement test:
    • Pain on dorsiflexion with thumb pressure over the anterior and anterolateral joint line.
    • Worse pain than dorsiflexion alone.

Investigation

X-Ray (XR)

  • Shows spurs or deformity.

MRI

  • Not usually necessary as the diagnosis is clinical.
  • May confirm synovitis, OCD, or AITFL meniscal-type tear.

Management

Non-Operative (First-line for all cases)

  • Physiotherapy.
  • Steroid injection.

Surgery (For failed non-operative management with debilitating pain)

  • Arthroscopic debridement is the procedure of choice.
  • Includes:
    • Debridement of synovitis (usually anterolateral).
    • Excision of impinging spurs.
    • Treatment of OCDs if found incidentally.

Outcome

  • Spurs often reform, but this is not correlated to progressive OA.
  • Good outcomes are typically achieved.

Posterior Ankle Impingement

Epidemiology

  • 10 times less common than anterior impingement.
  • More common in individuals performing equinus activities (e.g., ballet).

Causes

  • Impingement of posterior structures:
    • PITFL.
    • PTFL.
    • IML.
    • Os Trigonum or hypertrophied posterior talar process.
    • FHL tendon.
    • Posterior synovitis.
    • Subtalar arthritis or synovitis.
    • POMI lesion (Posterior Medial Impingement Lesion):
      • Caused by posteromedial soft tissue impingement.

Clinical Features

  • Posterior pain on equinus activity or ankle plantarflexion.
  • Pain reproducible on examination.
  • Resisted dorsiflexion of the big toe indicates FHL impingement.

Investigation

X-Ray (XR)

  • Lateral view in plantigrade position.
  • May show Os Trigonum or posterior process impingement.

MRI

  • Not usually necessary as diagnosis is clinical.

Management

Non-Operative (Always attempted first)

  • Activity modification.
  • Rest, NSAIDs, physiotherapy.
  • Steroid injection.

Operative (For persistent pain and failed non-operative management)

  • Posterior ankle arthroscopy (patient in prone position).
  • Portals stay lateral to FHL, either side of TA, to protect the tibial neurovascular bundle.
  • Sural nerve also at risk.
  • Debridement of tissues & excision of Os Trigonum can be performed.
  • Open debridement may be preferred as posterior arthroscopy is technically challenging.
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