Metatarsus Adductus Influence on Fifth Metatarsal Fractures: Radiographic Analysis

Submission Type: Base of the Fifth Metatarsal Fractures Research Type: Level 4 – Case series Introduction/Purpose: Metatarsus adductus is the most prevalent congenital foot disorder and results in soft tissue contractures and foot remodeling. Metatarsus adducutus can regress into numerous pathologies including hallux valgus, skew foot, and recurrent fifth metatarsal fractures. Fifth metatarsal fractures can also result from cavovarus foot deformity. There is no known literature directly comparing the percentage of fifth metatarsal fracture patients with either cavovarus foot deformity or metatarsus adductus. We hypothesize that having an elevated metatarsal adductus angle (MAA) of over 15 degrees predisposes patients to proximal fifth metatarsal fractures more than neutral or cavovarus deformity. Methods: Patients with fifth metatarsal fractures were assessed for the age, sex, fracture side, and fracture type. Fractures were radiographically classified as zone 1 (pseudo-Jones), zone 2 (Jones), or zone 3 (stress fracture). MAA and lateral Meary’s angle (LMA) of the affect foot measured radiographically. These measurements were used to quantitively compare the degree of metatarsus adductus and cavus deformity with the fracture type. Results: A total of 17 patients (4 men, 13 women) were identified with a mean age of 41. The patients who sustained a stress fracture had a mean MAA of 29.2 degrees (20.9 to 36.9) and LMA of 10.5 degrees of planus (-28.8 to +3). The Jones fracture group had a mean MAA of 19.7 degrees (19.1 to 20.7) and LMA of 1.1 degrees of cavus (-3.9 to 3.7). The pseudo-Jones group had a mean MAA 16.8 degrees (9.9 to 19.8) and LMA of 0.1 degrees of planus (-8.4 to 7.5). Conclusion: In conclusion, there is a high MAA in patients with fifth metatarsal Jones, pseudo-Jones, and stress fractures. The patient group with the highest MAA was the stress fracture group. Of note, patients with fractures do not necessarily have cavus deformity, but rather our results show that many patients have neutral to planus arches. There may be a role of custom shoe inserts to prevent future problems in patients with metatarsus adducts in the setting of bilateral pathology or recurrent fractures.