Purpose:​ Treatment options for hallux rigidus include several conservative and surgical measures. The aetiology leading to the disease has not sufficiently been examined so far.

Materials and methods:​ We analysed the anatomical configuration of the first metatarsal head of 120 metatarsal bones of different collectives aiming to find a possible correlation between the geometry of the first metatarsophalangeal joint and manifestation of hallux rigidus. Wet human cadaveric specimens and macerated dry specimens served as material. The relevant parameters used for analysis were an axis running through the metatarsal head, the anatomical longitudinal axis, and the radius of curvature of the first metatarsal bone.

Results:​ A significant difference was found in the radius of curvature of osteoarthritic and healthy subjects. Using the binary logistic regression, we were able to predict the probability of an occurence of hallux rigidus in dependence of the radius of curvature. Furthermore, we were enabled to calculate a correct prediction for the appearance of osteoarthritis in 85 % of the healthy subjects, and 73 % of the osteoarthritic subjects.

Conclusions:​ A consolidated view of the factors indicates that persons with a high risk for the appearance of hallux rigidus should be identified by measuring the radius of curvature in conventional radiographs and preventive measures to postpone the occurrence of clinically relevant hallux rigidus considered.