Application of Fresh Frozen Structural Allografts in Flatfoot Reconstruction

Submission Type: Other Research Type: Level 4 – Case series Introduction/Purpose: Various bone grafts (freeze-dried, fresh frozen) or substitute inserts (metal wedges) have been proposed to fill the osteotomy sites and provide structural support for the reconstruction of progressive collapsing foot deformity (PCFD). Among them, the fresh frozen structural allograft (FFSA) undergoes a preservation process involving freezing, which helps maintain its biological and structural integrity. FFSA avoids donor site morbidity while providing structural support. The clinical and radiographic outcomes of FFSA application for PCFD reconstruction-such as lateral column lengthening (LCL), Cotton osteotomy, and mid- and hindfoot fusions-have not been thoroughly investigated. We sought to investigate (1) the clinical and radiographic outcomes of FFSA use in LCL, Cotton osteotomy, and mid- and hindfoot joint fusions, and (2) whether additional fixation improved the rate of union in these patients. Methods: This study investigated PCFD patients who underwent surgical reconstruction performed by two fellowship-trained orthopedic foot and ankle specialists at two different academic institutions between April 2021 to October 2023. Patients with minimum follow up of 6 months were included in the study. A total of 40 patients were identified to have received FFSA as part of their reconstructive procedures, including LCL in 26 cases, Cotton osteotomy in 20 cases or subtalar joint fusion in13 cases, among others, such as medializing calcaneal osteotomy (Table 1). Clinical outcome, including pain improvement (VAS), intra- and post-operative complications, time to union, union rate, and changes in radiographic parameters before and after surgery, were assessed for each patient. The union time, union rate, and complications were comparatively analyzed between LCL fixation vs. non-fixation groups. Results: Forty patients who underwent PCFD reconstructive procedure using FFSA, with a mean follow-up of 24 months, were included. Radiographic union was achieved in 39/40 (97.5%) patients with 57/59 (96.6%) osteotomy or fusion sites impacted with FFSA. The average radiographic union time was 8.5±1.67 weeks. The AP T-1MT angle, Meary’s angle and calcaneal pitch angle significantly improved after surgery (Table 2, P< 0.001). There were 12 subjects in the non-fixation group (LCL and/or Cotton), and 28 in the fixation group. All LCL site impacted with FFSA achieved radiographic union, regardless of fixation. Complications occurred in 4 out of 12 cases in the non-fixation group and in 11 out of 24 cases in the additional fixation group (Table 3). Conclusion: FFSA provided satisfactory correction and union rate in patients undertaking reconstruction for AAFD. Our results demonstrated satisfactory union rates at the LCL, Cotton osteotomy and subtalar joint fusion sites. FFSA exhibits excellent natural healing potential, promotes bone regeneration, and possesses biomechanical properties capable of withstanding compressive force at open wedge osteotomy sites, often eliminating the need for additional fixation.