Ankle impingement can be classified as anterior, posterior, medial, or lateral.
Anterior Ankle Impingement
Most Common Causes
- Soft tissue impingement – Capsular synovitis blocking dorsiflexion.
- Talar or tibial spurs – Within the capsule (on tibia), impinging in dorsiflexion.
- 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.