Abstract
BACKGROUND: Isolated talonavicular arthritis is relatively uncommon and remains understudied. Furthermore, the alterations in plantar pressure distribution (PPD) following isolated talonavicular arthrodesis (TNA) have not been thoroughly investigated. This study aimed to evaluate PPD, clinical outcomes, and radiographic changes in patients undergoing unilateral isolated TNA. METHODS: Fifteen patients (63.2 ± 11.4 years) who underwent isolated unilateral TNA performed by a single surgeon were included. Postoperative PPD was evaluated across five foot regions at a mean follow-up of 33.3 ± 13.0 months, with comparisons made to the contralateral, unaffected foot. Clinical outcomes were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) score and the Foot Function Index (FFI). Radiographic evaluation included measurements of Meary's angle (MA), talonavicular coverage angle (TCA), and talus-first metatarsal angle (T1MA). Preoperative and postoperative data for these variables were compared to analyze surgical outcomes. RESULTS: Compared with the unaffected foot, pressure-time integrals (PTIs) in the forefoot, medial sole, and the entire plantar surface were lower on the affected side, while PTIs in the lateral sole, hindfoot, and midfoot were higher, though none reached statistical significance (P > 0.05). Clinically, AOFAS midfoot scores improved from 27.0 ± 21.3 to 78.9 ± 21.0 (P < 0.001), hindfoot scores from 25.1 ± 23.8 to 77.9 ± 14.9 (P < 0.001), and FFI decreased from 54.0% ± 19.8-16.5% ± 15.9% (P < 0.001). Radiographically, the TCA decreased significantly from 12.3° ± 6.3° to 4.7° ± 5.2° (P = 0.002), while changes in MA and T1MA were not significant (P = 0.078 and P = 0.123, respectively). Pedobarographic results on affected sides showed no significant correlation with either preoperative or postoperative AOFAS scores or FFI. However, these scores showed significant correlations with changes in T1MA between preoperative and postoperative assessments. Preoperative T1MA and postoperative MA were significantly associated with PTIs in specific regions of the plantar surface on the affected side. Additionally, BMI was correlated not only with PTIs in certain plantar areas but also with postoperative FFI. CONCLUSIONS: Isolated TNA was associated with improved functional outcomes and trends toward symmetrical PPD during walking on both sides, though larger studies are needed to confirm these observations. CLINICAL TRIAL NUMBER: Not applicable. LEVEL OF EVIDENCE: Level IV.