Bone-Block Lapidus Arthrodesis in the Treatment of the Collapsed Foot: Medium-Term Outcomes

Research Type: Level 2 - Prospective comparative study, Meta-analysis of Level 2 studies or Level 1 studies with inconsistent results Introduction/Purpose: Progressive collapsing foot deformity (PCFD), Hallux Valgus (HV), and Midfoot Arthritis (MA) are diseases that benefit from the Lapidus procedure due to its capability to provide a stable medial column while correcting the underlying deformity. However, the technique does not go without complications. First metatarsal shortening or dorsiflexion is common, which could be exacerbated by local anatomy and revision surgery settings. Restoring the first ray's length and sagittal plane position when treating these pathologies is paramount. A primary distraction and plantarflexion fusion with an allograft wedge has been advocated, potentially allowing improved deformity correction but risking increasing non-union. The objective of this study was to report medium-term follow-up results of the Bone-Block Lapidus Arthrodesis in patients with collapsed feet. Methods: This IRB-approved comparative prospective study assessed patients with PCFD, HV, and MA undergoing a Lapidus bone-block fusion between August 2020 and March 2023. Patients were operated on by a single fellowship-trained foot and ankle surgeon after clinical evaluation and a weight-bearing computed tomography (WBCT). After adequate joint preparation and trials, a Lapidus pre-shaped wedge allograft was placed and fixed using available implants. Adjunctive procedures were carried out as needed. Patients were kept non-weight bearing for six weeks and followed clinically, performing a WBCT at three months and subsequent follow-ups. Non-Union and complications were documented. Bone healing was determined by at least 50% of bone trabeculae crossing both graft interfaces at the WBCT. Forefoot arch angle (FFA), Meary’s angle, talonavicular coverage angle (TNCA), middle facet subluxation (MFS), and foot and ankle offset (FAO) were obtained as well as PROs, including PROMIS, PCS, and EFAS scores. Three fellowship-trained readers performed all assessments. Results: Sixty-four patients (67 feet) were included, age 54.0 (18-77), BMI 31.6 (29.6-33.6). Twenty-five PCFD, 23 HV, and 19 MA, average 17.3 months (4-33) follow-up. Cuneiform-post were used in 58.2%, plates/screws in 29.9%, and nails in 11.9%. Median allograft size was 8mm (5-19mm). The clinical non-union rate requiring reoperation was 11.9% (n=8). Minor complications were observed in 2.9% (2 dehisences) and major in 5.9% (3 infections and 1 contracture). Tomographic healing at 3 months occurred in 86.4% and in 66.7% at the most-recent WBCT (mean:10.1 months; 3-29). Improvement (ps < 0.001) in FAA of 6.9° (5.8-7.9), MFS of 22.6% (19.8-25.4), TNCA of 13.5° (12.1-14.3), Meary of 8.1° (6.7-9.5) and FAO of 3.8% (3.1-4.6) were found. Clinical outcomes were improved for VAS, PROMIS-PH, PROMIS-PI, PCS and EFAS (ps < 0.001). Conclusion: Although the Lapidus bone-block arthrodesis restored many of the markers associated with foot collapse and alignment, non-union rated was noted in 11.9%, which is in the top range of non-union rates reported in the literature for Lapidus arthrodesis. The use of allograft wedges in the fusion site probably explains our findings. The heterogeneous sample composed of considerably severe deformities should also be considered. Also, it is essential to highlight that WBCT findings of fusion site healing were initially 86.4% at 3 months and only 66.7% at the most recent follow-up. Additional studies and longer-term follow-up are needed. Study’s flowchart, Radiographic outcomes. Examples of surgeries and complications