Modified Posterior 2-Portal Technique of Arthroscopic Subtalar Joint Arthrodesis: Improved Pain and Functional Outcome at Mean 15Months Follow-up-A Case Series.

Abstract

Posterior arthroscopic subtalar joint arthrodesis (PASTA) via a posterior 2-portal technique has been described. We modified the surgical technique of creating the portals in the plane of the posterior facet (under fluoroscopy guidance) to enhance the ease of access to the joint, easier and complete removal of articular cartilage along with maintaining the heel height. Patients of post-traumatic subtalar joint arthritis, treated by PASTA during 2016 till 2019 were included in the study. Exclusion criteria: significant height collapse of calcaneum, lateral blow out or heel widening. The confirmation of subtalar joint as the source of pain was done by injection of local anaesthetic inside the joint under the image intensifier, bringing immediate pain relief. The primary outcome variables assessed were the pain and functional scores, assessed using visual analogue scale and AOFAS (American Orthopaedic Foot and Ankle Society) score, respectively. The total of 16 patients (7 males, 9 females) was included. The average age was 40.68years (23-58years). The underlying pathology in all patients was post-traumatic subtalar arthritis secondary to calcaneus fracture malunion in 8 patients (50%), talus fracture malunion in 4 (25%) and ligament injury in 2 patients (12.5%). No bone grafting was done. The mean duration of follow-up was 15.6months (9-24months). There was a statistically significant improvement (p < 0.001) in mean VAS score at follow up (2; range 0-4) as compared to the mean preoperative score (7; range 6-9). The AOFAS score also improved significantly (p < 0.001) at the follow up (mean 79; range 68-89) as compared to the preoperative score (mean 18; range 10-25). The posterior arthroscopic fusion of subtalar joint gives good results in terms of pain relief and functional scores when done for carefully selected patients of subtalar joint arthritis. Our slight modification of the original technique improves the ease of removing cartilage from subtalar joint with minimal height loss; thus, precluding any need for bone graft. It also makes the instrument movement easier inside the joint.