Hallux rigidus

The hallux rigidus is the degeneration of the joint formed by the phalanx of the first toe with the first metatarsal (metatarsophalangeal joint). These degenerative changes in the joint cause osteoarthritis of the joint , causing pain, loss of joint mobility and even immobilization of it.

The metatarsophalangeal joint of the first toe is made up of the first phalanx of the big toe and the head of the first metatarsal. The first toe together with the first metatarsal form a functional unit of the foot called the first radius. This first radius is a fundamental part in the development of human gait and allows the foot to support the weight of the body during its propulsion phase, which consists of the first toe taking off from the ground.
During the take-off of the first toe from the ground in the march, this toe must support a load equivalent to 2 or 3 times the weight of the person, which means that for a man weighing about 70 kg, at the time of take-off it is joint can support about 200 kg in just a few square centimeters, which suggests the enormous pressure that must withstand at this moment.

The foot is structured to withstand these pressures and especially the first spoke, which is the most robust and the largest. However, when there are diseases such as hallux rigidus, this joint loses its effectiveness, which causes an imbalance in the distribution of loads to the rest of the foot, injuring other areas of the foot that are not adequate to withstand such pressures and initiating the pathological process that surrounds it. to this alteration.

Del causes severe hallux

The cause of hallux rigidus is unknown. However, there are a series of factors that are associated with its appearance and which are the following:

• A longer or elongated first metatarsal, which is known by the technical name Index Plus.
• Structural or acquired dorsiflexion of the first metatarsal. This means that the first metatarsal is elevated relative to the ground plane, limiting the normal range of motion of the metatarsophalangeal joint.
• Congenital structural alterations of the first metatarsal.
• Foot muscle imbalances.
• Hypermobility of the first radius associated with pronation of the subtalar joint.
• Neurological disorders, which can cause spasticity of certain muscle groups in the foot.
• Dissecting osteochondritis secondary to acute trauma. A blow of a certain intensity received at the level of the metatarsophalangeal joint can cause an injury to the articular cartilage which will develop a degenerative change in this joint.
• Repeated microtrauma to the metatarsophalangeal joint.
• Systemic degenerative diseases such as rheumatoid arthritis, osteoarthritis, gout, etc.

Production mechanisms

All the causes of hallux rigidus converge in the same mechanism that initiates the degenerative process in the metatarsophalangeal joint.

The base of the phalanx of the first toe causes an injury to the head of the first metatarsal that erodes the articular cartilage and therefore damages the joint. The organism, in the attempt to repair the damage caused, produces a greater deposit of calcium at this level, with which small bone islets appear in the joint space. This process causes the limitation of the movement of the joint that with the passage of time the cartilage degenerates more and more and will end up fusing the first metatarsal with the phalanx of the first finger, which will cause the total immobilization of the joint due to the bone fusion that it is called synostosis.

One of the main causes that develop this process is the biomechanical alterations of the foot. The pronation of the joint of the posterior part of the foot causes hypermobility of the first metatarsal, developing a muscular imbalance that limits the movement of the phalanx of the first toe on the first metatarsal.

A longer first metatarsal causes it to collide with the phalanx of the first toe and therefore injure the articular cartilage due to increased impacts at this level.

Degenerative processes associated with diseases such as gout or rheumatoid arthritis also end up fusing the bones and preventing their movement, with the consequent functional limitation that this causes.

Symptoms of hallux rigidus

The symptoms of hallux rigidus are those related to the degenerative process of the joint:

• Limitation of joint movement of the metatarsophalangeal joint both in loading and unloading.
• Bony hypertrophy at the level of the joint that is evident on inspection or palpation of the same.
• Pain on palpation of the joint.
• Edema or swelling of the joint.
• Redness around the affected area.
• Appearance of a callus on the big toe in the inner plantar area of ​​the foot, which coincides with the joint formed by the two phalanges of the toe. This callus appears due to the translation of loads at this level due to the difficulty of being supported by the rigid metatarsophalangeal joint.
• Elevation of the big toe as a muscle compensation mechanism.
• Pain in the sole of the foot especially under the head of the second and fifth metatarsals.

Diagnosis of hallux rigidus

To diagnose hallux rigidus, the first thing to do is to take a complete medical history and a physical examination. A radiological study is necessary to observe the bone status of the metatarsophalangeal joint.

In the early stages, when there are still no visible signs by radiography, complementary studies such as nuclear magnetic resonance or bone scintigraphy can be performed.

To rule out basic pathologies such as gout or rheumatoid arthritis, a blood test can be done.

Treatment

Treatment of hallux rigidus depends on the stage of the disease.

In the initial stages, treatment will be aimed at reducing the symptoms caused by joint inflammation, as well as compensating for the biomechanical problems that occur in this type of foot. Pharmacological treatment consists of the administration of non-steroidal anti-inflammatory drugs (NSAIDs) that reduce inflammation and pain. Biomechanical compensation will be done through the establishment of an orthopedic treatment that will consist of an orthopedic insole that helps the foot to function properly and balanced. On occasions, this treatment can be accompanied by external modifications to the footwear that help to achieve a natural gait.

In the most serious cases, surgical treatment is chosen when conservative treatments ( orthotics ) are not successful. The surgery consists of reshaping the first metatarsophalangeal joint, either by carefully cleaning the joint or creating a new one by eliminating the arthritic elements (arthroplasty). In cases in which the bone state does not allow a joint reconstruction, an arthrodesis is chosen, which consists of fixing the joint with a sufficient angle to allow passage during ambulation.

How can I avoid it?

To prevent the appearance of hallux rigidus we will have to follow the following tips:

• Go to the specialist if we notice pain in the big toe joint or limitation of movement. This professional will be in charge of evaluating the condition of our feet and establishing an orthopedic treatment that prevents the progression of the disease.
• Avoid wearing high-heeled shoes that can increase pressure on the first metatarsophalangeal joint.
• Follow an appropriate training plan when playing sports that can damage the foot at this level. For example: soccer, polysalt sports (basketball, volleyball …).
• Checking the feet in case of degenerative joint diseases (rheumatoid arthritis, gout, osteoarthrosis …).