Kidner Procedure: Alone or with Subtalar Arthroeresis for Symptomatic Accessory Navicular in Flexible Flatfoot—Is Combined Treatment Essential?

Category: Midfoot/Forefoot; Other Introduction/Purpose: The presence of an accessory navicular (AN) can alter the attachment of the tibialis posterior tendon (TPT), potentially leading to a flattened medial longitudinal arch. The Kidner procedure addresses painful AN by correcting the abnormal TPT insertion, facilitating arch elevation. Subtalar arthroeresis (STA) prevents excessive subtalar joint eversion, preventing arch collapse in flexible flatfoot (FF) deformity. Literature on AN treatment seldom explores options in FF deformity. This study compares outcomes of Kidner alone versus Kidner with STA for symptomatic AN with FF, aiming to offer treatment insights. Methods: During January 2024, the PubMed, Embase, and Cochrane Library databases were systematically reviewed to identify clinical studies examining outcomes following the Kidner procedure alone and the Kidner procedure with STA for the management of symptomatic AN with FF deformity. The level of evidence (LoE) of the included studies was evaluated using the Journal of Bone and Joint Surgery criteria. Data regarding subjective clinical outcomes, radiological outcomes, and complications were extracted and analyzed. Results: This review included 14 studies, comprising one with Level II evidence, ten with Level III, and three with Level IV. Among 362 cases of symptomatic AN, 246 underwent the Kidner procedure, while 116 underwent Kidner + STA. The weighted mean age was 15.7 ± 3.9 years for the Kidner cohort and 12.8 ± 3.0 years for the Kidner + STA cohort, with WM follow-up durations of 67.8 and 31.3 months, respectively. Pre-operative VAS scores were 6.4 for Kidner procedures and 4.4 for Kidner + STA, with post-operative scores of 1.6 and 1.7, respectively. Pre-operative AOFAS scores were 46.0 and 57.7, with post-operative scores of 85.5 and 89.2, respectively. At final follow-up, Meary’s angle improved in the Kidner + STA cohort from 0.8 to 13.1 degrees. Conclusion: In conclusion, this review highlights the efficacy of both the Kidner procedure and its combination with subtalar arthroeresis (STA) in managing symptomatic accessory navicular (AN) with flexible flatfoot (FF) deformity. While the Kidner procedure effectively treats AN with flatfoot deformity, it carries a risk of arch collapse recurrence. Combining it with STA provides a more stable biomechanical construct for the tibialis posterior tendon (TPT), preventing arch collapse. Despite study limitations, personalized treatment approaches are crucial. Further research with larger cohorts and longer follow-ups is necessary to confirm and refine treatment strategies for this complex condition.