Hallux rigidus is a frequently occurring orthopedic disease that is based on wear and tear (arthrosis) of the metatarsophalangeal joint of the big toe. After hallux valgus, a malpositioning of the big toe with displacement of the metatarsophalangeal joint of the big toe towards the inner edge of the foot, it is the second most common functional disorder of the big toe. Often both diseases occur side by side.
The cause is probably a combination of overloading, unsuitable footwear, pre-existing foot malpositioning and a traumatic injury to the foot. The resulting wear and tear of the articular cartilage between the first metatarsal bone and the base of the big toe causes severe pain at rest and especially when walking. This is accompanied by an increasing and ultimately complete stiffening of the joint (hallux limitans).
Cause of the pain
Real joints (diarthroses), in contrast to fake joints (synarthroses), are characterized by cartilage-covered bone ends, between which the fluid-filled joint space is located. This is surrounded by a joint capsule. The cartilage provides a smooth surface and thus fulfills the function of absorbing the friction generated during the movement of the joint and protecting the underlying bone.
At the same time, it is pressure-elastic and can therefore absorb shocks. Excessive wear and tear of this cartilage due to age or disease results in the clinical picture of arthrosis. In this case, the protective hyaline cartilage layer increasingly thins out and is replaced by inferior fibrous cartilage and granulation tissue.
A regeneration of the hyaline cartilage is not possible. The degradation of the cartilage substance leads to a painful increase in pressure in the underlying bone tissue, resulting in microfractures. The rubbing of damaged cartilage and bone tissue against each other can sometimes even be heard and is called crepitation.
Small pieces of cartilage and bone can become detached from the remaining tissue. If they enter the joint space, this can cause a blockage of the joint. In order to be able to absorb the increased pressure, new bone formations (osteophytes) develop at the edge of the joint, which ultimately cause the joint base to widen and become visible in the X-ray image. All these remodelling processes and the lack of resilience of the replacement tissue cause the development of chronic inflammation and result in joint instability. Especially during movement, this sometimes results in severe pain.
