Arthroscopic os trigonum en-bloc removal outcomes at 6-month follow-up are better compared to Stieda's process resection in patients with posterior ankle impingement syndrome: a prospective comparative study.

OBJECTIVE: To evaluate the potential differences in American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score and Foot Function Index (FFI) at 6-month and 12-month postoperative follow-up of arthroscopic treatment for posterior ankle impingement (PAIS) between os trigonum (OT) and Stieda's process (SP) patients.
METHODS: Thirty consecutive patients (32 ankles) treated in our Institution for PAIS with posterior arthroscopy were prospectively enrolled in the study from December 2012 to July 2019. Indications were patients with PAIS with persistent symptoms following conservative management. Exclusion criteria were the coexistence of concomitant pathologies and patients who underwent additional surgical procedures. An independent investigator interviewed and evaluated the patients according to the AOFAS hindfoot score and FFI preoperatively, at 6-month and 12-month follow-up.
RESULTS: Except for AOFAS scores in the SP group (MD (mean difference) 11.28, p=0.08), patients undergoing arthroscopic treatment for bony PAIS had an overall significant improvement in AOFAS score (OT MD 22.29, p<0.05) and FFI (OT MD -70.07, p<0.05; SP MD -50.96, p<0.05) from their preoperative scores at 6-month follow-up. Similarly, a significant improvement in AOFAS score (OT MD 5.78, p=0.01; SP MD 12.14, p<0.05) and FFI (OT MD -9.36, p=0.04; SP MD -26.43, p<0.05) was observed from the 6-month to 12-month follow-up in all groups. At 6-month follow-up, the OT group had significantly better FFI outcomes (MD -33.57, p=0.04) compared with the SP group. No differences were found by group when comparing AOFAS score and FFI score at 12-month follow-up.
CONCLUSIONS: When comparing patients undergoing OT excision or SP resection, better FFI outcomes were observed in the OT group at 6-month follow-up. LEVEL OF EVIDENCE: Prospective comparative study. Level II. © International Society of Arthroscopy, Knee Surgery and Orthopaedic Sports Medicine 2021. No commercial re-use. See rights and permissions. Published by BMJ.