No abstract

The resection of os trigonum or posterior talar process for posterior ankle impingement is a technically easy and frequent operation. So far, the scientific literature has focused only on the surgical approach and perioperative problems. However, the author has encountered unfavorable followup results (professional athletes had to stop their career), which also other surgeons tell to have encountered. This study aims to describe for the first time this complication rate and possible reasons therefore. Methods: From 3/11 to 7/15 29 patients (17male, 12 female, 32+/-14 years) with 30 feet were operated (22 endoscopic, 8 open resections). Average followup was 27+/-13 months. All charts and pre-and postoperative radiographs were retrospectively evaluated. Patients were grouped into "no complications", "minor temporary (< 3 months)", "major follow up (end of athletic career)" complications. The following radiographic parameters were measured referenced on the intersection of the talar radius with the calcaneus (Fig. 1): (1) length of posterior talar process/ os trigonum, (2) length of the calcaneus below the posterior process/os trigonum, (3) length of the uncovered subtalar joint after resection. Results: The major complication rate was 13.3% (4 of 30 feet, 2 os trigonum, 2 posterior talar process): all 4 had symptomatic talar edema and 3 of 4 had symptomatic subtalar osteoarthritis. 1 minor complication (persistent pain for 3 months) was found. The length of the posterior talar process was preoperatively 9.37 +/-2.89mm (os trigonum 8.62+/-2.62mm) postoperatively 0.64+/-1.8mm. The length of the posterior calcaneus preoperatively was 8.35 +/-4.63mm, postoperatively 1.97 +/-3.0mm. The uncovered subtalar joint surface postoperatively was 1.77+/-2.92mm. All patients with major complications showed retrospectively what we call the "deadly configuration": the radius of the talus ends within the subtalar joint. Consequently the free subtalar joint surface was significantly larger (6.4mm +/-3.33) in feet with major complications than in feet without (1.06mm +/-2.15, P < 0.001). Feet without complications but with this deadly configuration (7/26) had a lower free subtalar surface (3.27mm +/-1.81, P=0.09) than feet with major complications. Conclusion: The resection of os trigonum or posterior talar process has a high complication rate of 13.3% with symptomatic talar edema and subtalar osteoarthritis at follow up which can be career-ending in professional athletes. The only risk factor found was what we call the "deadly configuration" characterized by the ending of the talar radius into the subtalar joint. In such cases, the resection has to be made sparingly preferably not anterior into the subtalar joint and patients have to be informed about this possible unfavorable course.