Thank you, Dr. Bikos. Good afternoon, everyone. My name is Alan Shamrock. I'm a second-year resident at the University of Iowa. Truly a pleasure to be here. Today I'll be discussing patient positioning and arthroscopic portal placement for subtalar fusion. I would be remiss if I did not take the time to thank my co-authors for their contributions to this study for which we have no disclosures. Subtalar arthrodesis is performed for patients with arthritis, coalition, and inflammatory joint disease affecting the subtalar joint without a large hindfoot deformity. It was traditionally done via an open approach utilizing a lateral incision over the sinus tarsae. Arthroscopic subtalar arthrodesis was first described in 1992. It was billed as a minimally invasive option that was less threatening to neurovascular structures in the soft tissues. Subsequent studies went on to report great patient satisfaction, fusion rates, and low morbidity. The procedure was originally performed with the patient in the lateral decubitus or the supine position using anterior lateral and posterior lateral portals based around the fibula. More recently, several authors have described a posterior technique in which patients are positioned prone with posterior medial and posterior lateral portals with or without an accessory lateral portal. To date, studies comparing these techniques are lacking. The purpose of the current study was to investigate how patient positioning and portal placement affects outcomes in morbidity following arthroscopic subtalar fusion. We originally hypothesized that supine or lateral positioning with lateral portals would demonstrate a higher rate of neurovascular injury given the proximity of the serral nerve. To answer our study question, a systematic review was performed according to PRISMA guidelines. All original studies with reported complication rates and a description of operative technique for arthroscopic subtalar fusion were included. Two independent reviewers collected patient demographics, operative positioning, portal placement, complications, and outcomes including time diffusion and AOFAS scores. Complications of interest included nonunion, painful hardware, reoperation, and neurovascular tendon injury. Patients from included studies were placed into one of three groups, the lateral group if they were positioned lateral or supine with lateral-based portals. The prone two-portal group if they were positioned prone with posterior medial and posterior lateral portals. And finally, the prone three-portal group if posterior medial, posterior lateral, and accessory lateral portals were utilized in the prone position. This figure illustrates our search strategy results and review process. We were ultimately left with 20 articles that satisfied our inclusion criteria looking at 484 feet and 468 patients with a mean follow-up of 36 months. In reporting studies, mean AOFAS scores improved from 46.3 to 81.6 following surgery. Successful fusion was seen in 95.8% of cases in a mean of 10.9 weeks. Shown here is a table breaking down our adverse events of interest. The total complication rate was similar between the three study groups at around 18%. Furthermore, there was also no significant difference in neurovascular injury, symptomatic calcaneal screws, or repeat surgery between the three groups. A difference was seen regarding the rate of nonunion. The two portal prone groups sustained nine nonunions which is significantly more than the two found in the lateral group. However, the nonunion rate within the three portal prone group in the lateral group trended toward but did not reach statistical significance. The current study is limited by its systematic review design with inherent publication bias. Additionally, we were unable to assess certain patient demographics such as BMI or smoking that have been shown to affect outcomes. Furthermore, we were unable to account for surgeon experience in their comfort level without arthroscopic subtalar arthrodesis. Lastly, there was a wide variability in the reporting of metrics including the definition of fusion, use of bone graft, and the type and number of screws used for fixation. In conclusion, arthroscopic subtalar arthrodesis is an effective option for subtalar joint pathology. Contrary to our initial hypothesis, there was no difference in neurovascular complications between the study groups. We identified a higher rate of nonunion when the patient is position prone and posterior medial and posterior lateral portals without an accessory lateral portal are utilized. All this finding has not been previously described and may relate to incomplete visualization and preparation of the entire posterior facet. Based on these findings for their large scale, prospective studies are warranted. Thank you.

Alan Shamrock

patient positioning

arthroscopic portal placement

subtalar fusion

subtalar arthrodesis