Plate Fixation and Hallux Valgus Deformity Impact on Nonunion Rates in First Metatarsophalangeal Arthrodesis: A Retrospective Cohort Study.

BackgroundThe combined effect of fixation type and preoperative deformity together might influence the union rate after the first metatarsophalangeal (MTP) arthrodesis. This study aimed to compare the nonunion and failure rate of dorsal locking plate versus cross-screws for the first MTP arthrodesis considering the preoperative deformity, including hallux valgus versus rigidus. We secondarily aimed to compare the observed nonunion rate with the rate in the systematic reviews.MethodsThis was a retrospective cohort study including 372 patients and 378 feet. The surgical technique was identical except for the use of a dorsal locking plate in 181 (49%) and cross-screws in 191 (51%) MTP joints. The radiographic union was assessed at 3 months postoperative. Those who did not heal by the 3-month follow-up were categorized as a "symptomatic" versus "asymptomatic" nonunion. Those categorized as nonunion after 3 months were followed until union occurred.ResultsThe results demonstrated that dorsal locking plate fixation (OR = 10.1, 95% CI: 1.3-80) and hallux valgus deformity (OR = 4.7, 95% CI: 1.2-18) were significantly associated with a higher nonunion rate. At 3-month follow-up, a total of 19 (5%) patients showed nonunion. Of the total nonunions, 15 (79%) were fixed by the locking plate, and 4 (21%) were fixed by cross-screws. Of the 15 nonunions with plate fixation, 6 (40%) underwent a second surgery due to device failure, while none of the cross-screws required a second surgery. Out of the 6 secondary surgeries, 5 (83%) demonstrated a nonunion with valgus deformity and 1 required removal of hardware due to prominent hardware.ConclusionOur results support that a dorsal locking plate for the fusion of a hallux valgus deformity is associated with a significantly higher risk of symptomatic nonunion and a secondary surgery compared to cross-screws, possibly due to the failure of the plate in neutralizing the medio-lateral deforming forces.Levels of Evidence:Level IV, Retrospective Cohort.