SLR - August 2013 - Deena Horn
Reference : Jae Hoon Ahn MD, Yoon-Chung Kim, and Ha-Yong Kim. Arthroscopic Versus Posterior Endoscopic Excision of a Symptomatic Os Trigonum: A retrospective Cohort Study. American Journal of Sports Medicine 2013 41: 1082-89.
Scientific Literature ReviewReviewed by: Deena Horn, DPM
Residency Program: Inova Fairfax Hospital, Falls Church, VA
Podiatric Relevance: Posterior ankle impingement syndrome, or posterior talar impingement, is often associated with pain during forced plantarflexion of the foot commonly secondary to an os trigonum. An os trigonum is reported to be present in 2.5 to 14 percent of the population and can result in inflammation of posterior ankle soft tissues, osseous injuries or combination of both. After failed conservative treatment, removal of the accessory bone has been reported to be a successful treatment measure. Classically, the bone was removed through a lateral approach; however, with current technology, both endoscopic and arthroscopic techniques have been used.
Methods: The authors performed a retrospective review of all patients that underwent excision of symptomatic os trigonum either by arthroscopic or posterior endoscopic technique between January 2004 and November 2010. The exclusion criteria were combined lateral ankle instability, OCD of the talus, FHL tendonitis, arthritis or inflammation of the ankle or subtalar joint. Subjective patient measures were recorded using the Visual Analog Scale (VAS), American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale, and Maryland Foot Score (MFS). Preoperative MRI were performed on all patients with the size of the accessory bone measured as the product of the short and long axis diameter on T1 weighted imaging.
Arthroscopic excision was performed with patient supine using an Acufex ankle distracter and a 2.7mm, 30 degree arthroscope through the anterior and posterolateral portals. The posterior endoscopic procedure was performed with the patient in prone position with a 4.0mm, 30 degrees arthroscope through posteromedial and posterolateral working portals.
Results: Twenty-eight patients were included in the study; 16 patients with arthroscopic excision and 12 with posterior endoscopic excision. There was a mean follow-up of 30 months. In the arthroscopic group, the mean VAS score improved from 6.3 to 1.2, the mean AOFAS score improved from 64.8 to 89.9, and the mean MFS improved from 61 to 89.6. In the posterior endoscopic group, the VAS score improved from 6.7 to 1.2, the mean AOFAS score improved from 63.8 to 89.9, and the mean MFS improved from 62.5 to 88.3. There was no significance between the two groups with respect to preoperative or postoperative VAS, AOFAS score and MFS. The mean surgery time was 39.4 minutes for arthroscopic group and 34.8 minutes for the posterior endoscopic group. All patients were able to return to the same level of sporting activity within three months after surgery. Two patients underwent both arthroscopic and endoscopic procedures because it was too technically difficult during the initial arthroscopic procedure. Two cases had temporary sural nerve dysesthesia -- one in each group -- and no other postoperative complications occurred.
Conclusions: The results of this study demonstrate that both arthroscopic and endoscopic approaches for excision of an os trigonum are safe and effective ways to treat posterior ankle impingment syndrome. Both techniques require a highly skilled physician, with the arthroscopic procedure being more technically demanding, especially with larger os trigonums.