Hindfoot Arthrodesis Screw Position and Trajectory Effect on Talus Subsidence When Performed With Total Ankle Arthroplasty

Background: Total ankle arthroplasty (TAA) is increasingly being recognized as an effective surgical option for end-stage ankle arthritis. Associated hindfoot arthrodesis procedures are at times needed to correct malalignment or to address adjacent joint arthritis. Results following TAA and associated hindfoot arthrodesis have at times been underwhelming and the devascularization of the talar blood supply has been postulated as a potential cause. This study explored the association between hindfoot arthrodesis fixation and talar component subsidence. Methods: The study included 81 consecutive patients who underwent a TAA with either an isolated subtalar arthrodesis or combined subtalar and talonavicular arthrodesis with a minimum of 2 years of follow-up. Radiographic and clinical evaluations including patient-reported outcomes were performed at each postoperative visit. The primary outcome measure was the presence of talar component subsidence while patient-reported outcomes were the secondary outcome measure. Results: 30.9% of patients had evidence of talar component subsidence. Subsidence was seen in 55.5% of patients with dorsal to plantar subtalar fixation compared to 11.1% of patients with plantar to dorsal screws ( P < .001) and in 44.4% of patients with screws violating the sinus tarsi compared to 3.7% of patients without screws in the sinus tarsi ( P < .001). Screws that were placed from dorsal to plantar were more likely to violate the sinus tarsi ( P < .001). Patients with evidence of talar subsidence reported higher pain scores and lower functional scores. There were 8 TAA failures, and the presence of dorsal to plantar screws was associated with failure ( P < .01). Conclusion: Screws that are placed across the subtalar joint from a dorsal to plantar approach are more likely to violate the sinus tarsi, contributing to a significantly higher rate of talar component subsidence when associated with TAA. Level of Evidence: Level II, prospective comparative series.