Posterior ankle impingement and related osseous anomalies

Posterior ankle impingement is an uncommon condition characterized by posterior ankle pain during plantar flexion. Aim of this thesis was to provide more insight in the epidemiologic and geometric characteristics of the os trigonum, the role of conventional radiographs, and surgical treatment of posterior ankle impingement and the long term outcomes. In addition, related osseous pathologies were addressed, as well as new insights on their treatment.
The prevalence of the os trigonum was determined in an asymptomatic population. With a prevalence of 30.3% in patients without posterior ankle complaints, the prevalence is higher than hitherto reported.
To study the differences between symptomatic and asymptomatic ossa trigona, the geometrical characteristics of symptomatic and symptomatic ankles were compared. The symptomatic ossa trigona were larger and calcifications were more often seen in the symptomatic side.
Different projection angles were systematically compared using DRR to find the optimal radiographic views to detect an osseous impediment. Views with the foot in 25-35 degrees of exorotation were found to have the highest sensitivity for detecting an os trigonum or hypertrophic posterior talar process and showed highest interobserver reliability.
In a large retrospective case series endoscopic treatment of posterior ankle impingement showed to yield good long term outcome with a low recurrence rate. Additional flexor hallucis longus tendinopathy showed to result in lower patient satisfaction and higher recurrence rate.
In a meta-analysis no clinical relevant difference in postoperative AOFAS score, patient satisfaction and return to pre-injury level of activity between open and endoscopic techniques were found. Complication rates were lower with endoscopic treatment in the ‘fair’ and ‘good’ methodological quality studies.