Lag Screw with Plantar Plating for Naviculocuneiform Arthrodesis in Progressive Collapsing Foot Deformity

CATEGORY: Midfoot/Forefoot INTRODUCTION/PURPOSE: Medial column procedures are a common adjunct to progressive collapsing foot deformity (PCFD) correction. In particular, naviculocuneiform (NC) arthrodesis could be performed when degeneration or instability at the NC joint is contributing to arch collapse. Plantar plate fusion resists gapping along the tension side of the joint, potentially reducing risk of non-union and recurrent deformity. Additionally, by placing the hardware in a plantar location there is an increased soft tissue envelope to function in a protective matter and eliminate the possibility of hardware prominence and tendon irritation. The purpose of this study was to analyze short-term clinical and radiographic outcomes of NC fusion using a lag screw with plantar plating technique. METHODS: A single-surgeon retrospective case series was performed on patients with PCFD and medial arch collapse treated with NC arthrodesis using a lag screw plus plantar plating technique between January 2016 and December 2019, with a minimum six month clinical and radiographic follow up. Patients undergoing revision NC joint arthrodesis, patients with incomplete imaging, or an arthrodesis technique that did not utilize NC joint plantar plating were excluded. Demographic data, perioperative data, complications, and reoperations were recorded from electronic medical records. Pre-operative AOFAS midfoot scores were calculated at the initial clinic visit and then again at the patients' most recent follow-up. In the case of most recent follow up occurring prior to six months post-operatively, a telemedicine visit was performed. Anteroposterior (AP) and lateral talo-first metatarsal angles, talonavicular coverage angle, and calcaneal pitch were measured independently by three authors. Fusion was confirmed radiographically and computed topography when union was in question. RESULTS: Nineteen patients (15 female, 4 male; 11 right, 8 left) with a mean age of 56.6 years and a mean follow-up of 21.0 +- 13.4 months were reviewed. A mean 3.4 concomitant procedures were performed at the time of NC fusion. AP talo-first metatarsal angle (18.9° to 5.2°), lateral talo-first metatarsal angel (-18.7° to -4.4°), talonavicular coverage angle (28.1° to 7.4°), and calcaneal pitch (14.6° to 20.1°) all improved significantly (p<0.001). Fusion was confirmed in 15 (79%) patients at a mean 6.1 +- 3.5 months. Mean AOFAS midfoot scores improved from 51.7 +- 13.0 preoperatively to 82.6 +-12.8 (p<0.001) at an average 21.0 +- 13.4 months follow up. Two patients experienced broken hardware, one patient fractured through flexor digitorum longus (FDL) transfer site and experienced non-union requiring revision at 9.5 months, one patient experienced symptomatic lateral column hardware requiring removal, and one patient experienced non-union requiring revision at 13.5 months. CONCLUSION: Lag screw with plantar plating is a technique for NC arthrodesis that is associated with a higher non-union rate (21%) than what is reported in the literature. Nonetheless, at short term (mean 21 months) follow up, the technique proved capable of correcting medial arch collapse through the NC joint when used in conjunction with adjunctive soft tissue and bony procedures. Plantar plating technique resulted in no instances of symptomatic hardware along the medial midfoot. Addressing medial arch collapse with NC arthrodesis resulted in significant improvement of both radiographic outcomes and patient reported clinical outcomes.