Preoperative Talocalcaneal Distance and Subtalar Fusion are Not Associated with Worse Patient-Reported Outcomes in Progressive Collapsing Foot Deformity
Authors: DiGiovanni Grace , Jones Agnes , Masry Seif El , Deland Jonathan T. , Ellis Scott J. , Conti Matthew S. 
Published: December 2024

Category: Hindfoot; Other Introduction/Purpose: As progressive collapsing foot deformity (PCFD) advances, narrowing between the lateral talar process and calcaneus at the angle of Gissane often occurs. This signifies more advanced peri-talar subluxation and may result in sinus tarsi impingement. However, the clinical significance of narrowing at the angle of Gissane and its effect on patient-reported outcomes following a flatfoot reconstruction is unknown. The primary aim of this study was to investigate if there was a relationship between preoperative talocalcaneal distance between the lateral talar process and calcaneus at the angle of Gissane and two-year postoperative outcomes in patients with flexible PCFD who underwent a reconstruction of their deformity. A secondary aim was to compare this cohort of patients to those who underwent a subtalar arthrodesis. Methods: Seventy-six consecutive patients >18 years old who underwent reconstruction of a flexible PCFD with (fusion cohort, n=40) or without (non-fusion cohort, n=36) a subtalar arthrodesis, had preoperative weightbearing CT (WBCT) scans, and had preoperative and ≥two-year postoperative PROMIS scores were included. Patient were excluded if they underwent a talonavicular fusion. Patients underwent a subtalar fusion if their chief complaint was lateral sinus tarsi pain. The talocalcaneal distance was measured on preoperative WBCT scans as the closest distance between the lateral process of the talus and the superior aspect of the calcaneus (Jeng et al 2018). Spearman correlation coefficients and multivariable regression analyses controlling for subtalar fusion were calculated between preoperative talocalcaneal distance and postoperative PROMIS scores. Due to the small sample sizes, descriptive statistics were reported as median and interquartile range (IQR), and differences between the non-fusion and fusion cohorts were determined using Mann Whitney U tests. Results: The median preoperative talocalcaneal distance for the non-fusion and fusion cohorts were 1.2 mm (IQR 0.75 mm, 1.7 mm) and 0.6 mm (IQR 0.1 mm, 1.1 mm, P=0.007), respectively. For the non-fusion cohort, there was no correlation between preoperative talocalcaneal distance and two-year postoperative PROMIS Physical Function (rho=0.198, P=0.891), Pain Interference (rho=-0.0136, P=0.891), and Pain Intensity (rho=-0.038, P=0.923). Similarly, there was no correlation between preoperative talocalcaneal distance and two-year postoperative PROMIS scores for the fusion cohort (all P>0.80). At two-years postoperatively, there was no difference in PROMIS scores between the non-fusion and fusion cohorts (all P>0.10) (Table 1). When controlling for talocalcaneal distance, there was no difference in postoperative PROMIS scores between the fusion and non-fusion cohorts (all P>0.30) (Figure 1). Conclusion: In PCFD patients undergoing a flatfoot reconstruction, there was no correlation between preoperative talocalcaneal distance and two-year postoperative patient-reported outcomes. Additionally, there was no difference in outcomes between patients who underwent a subtalar arthrodesis compared with patients who underwent a reconstruction even when controlling for talocalcaneal distance. Our results suggest that preoperative talocalcaneal distance is not an indication for subtalar arthrodesis. Additionally, patients indicated for a subtalar fusion for correction of their flexible PCFD deformity do not have worse outcomes than patients who did not undergo a subtalar arthrodesis regardless of preoperative talocalcaneal distance.