Soft tissue injuries
The normal ankle has a triangular soft tissue component in the anterior ankle space (Tol + van Dijk 2004). This can sometimes be seen on MR scans of the ankle. When the ankle is dorsiflexed 15 deg, Tol and van Dijk found that the anterior ankle space was diminished, which could account for impingement pain, especially if the anterior soft tissues were hypertrophied after trauma.
The anterior inferior tibiofibular ligament may be torn and its inferior margin impinge in the ankle joint, causing the “meniscoid lesion”. This may be commoner in a group of people who have a particularly low attachment of the inferior leaf of the ligament
Damage to the inferior tibiofibular joint may cause scar tissue or synovitis to prolapse into the ankle. Schaffler et al (2003) described this condition in 70% of patients with ankle impingement compared with 49% of a control group with other proven ankle pathologies, although their selection criteria may have created bias. They also found that MR had a sensitivity of 89% and a specificity of 100% for syndesmotic impingement tissue.
Causes of anterior ankle impingement
Anterolateral synovitis - a common cause of impingement
Bony spurs, on the anterior margin of the distal tibia or the talar neck, may be found in 70% of footballers and are also found in people who play other sports or none. Berberian et al (2001) found that tibial spurs generally occur lateral to the midline of the ankle joint, while talar spurs are medial. Spurs may cause pain by direct pressure on one another or by nipping anterior soft tissue; as the spurs do not usually overlap (Berberian et al 2001) the latter seems more likely. Scranton and McDermott (1992) produced a classification of anterior ankle spurs.
Spurs were thought to arise because of chronic repeated traction from the anterior ankle capsule. However, Tol and van Dijk(2004) showed that the capsule is attached 4-9mm above the ankle joint line and therefore clear of the site of formation of spurs. Indeed, this can be observed at arthroscopy. Tol and van Dijk found that the joint cartilage extended 2-3mm onto the nonweightbearing surface of the tibia and hypothesised that damage to this cartilage sets up a repair mechanism that produces a spur. On the talus, Hayeri (2009) found that medial spurs occured inside the capsule, while lateral spurs appeaeared to grow within the capsule itself. Isolated medial spurs were six times commoner than lateral spurs, while 21% had both medial and lateral spurs.
Anterior ankle spurs. Tibial spurs tend to be lateral, talar spurs medial
Small tibial spur
Large tibial and talar spurs