Prevalence and functional implications associated with the presence of the hallux interphalangeal ossicle: pilot study.

Abstract

Objective: The presence of ossicles or accessory bone in the interphalangeal joint of the hallux has been inconsistently reported in the literature, with a high degree of variability depending on the imaging diagnostic method used. The general aim of this preliminary study was to analyze the prevalence, laterality, and size, as well as the biomechanical implications (joint range alterations) associated with the presence of this ossicle. Method: To this end, a case-control study was conducted (individuals with the ossicle vs. those without it) identified by ultrasound, in which the range of motion of the hallux interphalangeal and metatarsophalangeal joints was explored both in open kinetic chain and loaded conditions, using an angle measurement program. The sample consisted of 172 feet from 86 subjects (123 women and 49 men), with an average age of 25.22 ± 4.47 years, who met the inclusion criteria. Results: Forty-one percent of the individuals examined had an ossicle in the interphalangeal joint of the first toe, compared to 59% who had no ossicle. The analysis showed significant differences between the groups in terms of the average range of motion in extension, with a greater range in the case group compared to the control group. Conclusion: The presence of the interphalangeal ossicle appears to influence the biomechanics of the first ray, potentially affecting the propulsive phase of gait. This should be taken into account, as the presence of this accessory bone may be considered an underdiagnosed entity.