What causes hallux rigidus ?
Most commonly the cause is multifactorial. This means a combination of reasons, partly inherited partly related to previous activities/events. Very occasionally it occurs as a direct result of an injury to the joint (big toe MTP joint )
I have a bunion but my toe is also very stiff and painful.
It is certainly possible to have a bunion and hallux rigidus at the same time. Usually one is more of a problem than the other. The nature of the surgery is generally decided by which the more prevalent problem is. For example if there were only mild arthritic symptoms with a more painful bunion then a debridement of the joint (a small operation, see below) could be combined with a correction of the hallux valgus.
If the arthritic symptoms are more problematic then the main operation should be aimed at this with either a fusion or a modified Kellers/Hamilton operation. These pictures illustrate such a case (in a patient with rheumatoid arthritis as well as lesser toe deformities). The left foot has undergone a fusion of the big toe and correction of the lesser toes.