No Association Between Cavovarus Alignment and Risk of Non-Union or Delayed Union in Jones Fractures

Abstract

Category: Midfoot/Forefoot; Other Introduction/Purpose: It has been well documented in the literature that fractures of the base of the fifth metatarsal are often associated with varus hindfoot alignment. Zone two fractures at the metaphyseal-diaphyseal junction, commonly referred to as Jones fractures, have specifically been noted to have a higher incidence of delayed union and nonunion. This has historically been attributed to the tenuous blood supply in this region. Although it is known that hindfoot varus may predispose to these fractures, there is little information on whether a cavovarus alignment may also contribute to the increased risk of nonunion. The purpose of this study is to determine whether cavovarus foot alignment is associated with delayed union or nonunion in Jones fractures. Methods: We identified patients who sustained a proximal fifth metatarsal fracture between the years 2016-2021 at a single academic institution. Weightbearing foot radiographs were then reviewed to identify zone 2 fractures. Talo-first metatarsal, talonavicular coverage, and talocalcaneal angles were then measured on the AP view and calcaneal pitch, talocalcaneal, and talo- first metatarsal angles were measured on the lateral view to assess foot alignment. The primary outcome measure was the presence of a nonunion or delayed union. T-tests, Mann Whitney U tests, and ANOVA analyses were conducted to assess for differences. Results: We identified a total of 117 patients with 118 zone 2 proximal fifth metatarsal fractures. Of those fractures, there were 23 of which were considered either delayed union (n=8) or nonunion (n=15). Similar rates of nonunion and delayed union were observed between patients undergoing nonoperative and operative management of their Jones fractures (p=0.514, p=0.200, respectively). For all patients with a nonunion or delayed union, no differences in anteroposterior (AP) talo-first metatarsal angle, AP talonavicular coverage angle, AP talocalcaneal angle, lateral calcaneal pitch, lateral talo-first metatarsal angle, or lateral talocalcaneal angle from those with expected healing were observed (p = 0.773, p = 0.084, p = 0.874, p = 0.751, p = 0.471, and p = 0.386 - respectively). Conclusion: Overall, no measured foot alignment values (talo-first metatarsal angle, talonavicular coverage, talocalcaneal angle, or calcaneal pitch) were statistically associated with increased risk of delayed union or non-union among patients with Jones fractures undergoing either operative or non-operative treatment. Furthermore, there was no measured difference in these foot alignment parameters between those patients undergoing operative treatment and those undergoing non-operative treatment. In conclusion, cavovarus alignment is not associated with an increased risk of non-union or delayed union in the operative or non-operative treatment of Jones fractures.