Foot osteoarthritis
Osteoarthritis corresponds to a loss of cartilage substance affecting the two bony segments that make up a joint. The loss of cartilage substance leads to narrowing of the joint space, with bone production called osteophytosis, which corresponds to an increase in the bone surface in an attempt to better distribute joint pressure in the case of cartilage damage. Osteoarthritis does not affect all joints, and notably not all those of the foot.
What is foot osteoarthritis?
Osteoarthritis of the foot can affect:
- The hindfoot, corresponding to the subtalar joint formed by the talus and the calcaneus.
- The midfoot, corresponding to the talonavicular, calcaneocuboid joints, calcaneus, and the tarsometatarsal joints, known as Lisfranc joints.
- The forefoot with the metatarsophalangeal and interphalangeal joints.
What are the symptoms of foot osteoarthritis?
Not all arthritic joints are necessarily painful. In case of pain, it is usually mechanical in nature, meaning it occurs when the joints are moved and subsides at rest. This pain can also have an inflammatory aspect, meaning it persists at rest, especially during osteoarthritis flare-ups. The location of the pain depends on the joint or joints affected.
In cases of osteoarthritis, there is generally associated joint stiffness.
During osteoarthritis flare-ups, there is an increase in the inflammatory level of the joint with an increase in the secretion of joint fluid, which can cause visible joint swelling.
The different types of foot osteoarthritis
Osteoarthritis of the Forefoot
Osteoarthritis of the forefoot joints most frequently involves the metatarsophalangeal and interphalangeal joints. Stiffening of these joints causes a decrease in joint range of motion, which may be associated with pain during the gait cycle.
A significant trauma is often found in the patient's history when they recall it. Trauma generally occurs up to 10 to 15 years before the symptomatic manifestations of osteoarthritis.
Articular fractures of the metatarsal heads and the base of the phalanges are potentially highly arthrogenic, meaning they carry a risk of osteoarthritis, especially in cases of initial articular displacement of the fractures and the extent of this displacement. These displaced articular injuries are all the more at risk for osteoarthritis if the fractures have not been operated on or have been inadequately reduced.
Severe sprains of the toes can lead to chronic articular instabilities responsible for cartilage degradation and secondary osteoarthritis.
Hallux valgus is a joint instability that can cause cartilage degradation due to increased shear stress on the joint; cartilage lesions may appear as the deformity progresses. This condition is then referred to as hallux rigido valgus.
Osteoarthritis of the Midfoot
Osteoarthritis of the joints forming the Lisfranc joint is post-traumatic, usually occurring after high-energy trauma to the bases of the metatarsals. Lisfranc injuries can initially go unnoticed on x-rays. For this reason, a foot CT scan is necessary to look for Lisfranc injuries when there is significant post-traumatic swelling and normal x-rays. There are so-called subtle Lisfranc lesions, which can be clinically suspected by the presence of an abnormally large hematoma on the foot, slight interosseous gaps on x-ray, and minimal bony avulsions at the site of the Lisfranc ligament insertions on CT scan.
Talo-navicular osteoarthritis can be post-traumatic, with navicular fractures being particularly arthrogenic and difficult to repair surgically. Instability of the talo-navicular joint present in flat feet can also lead to osteoarthritic degeneration of this joint. In chronic inflammatory diseases, especially rheumatoid arthritis, it is possible to develop talo-navicular arthritis with spontaneous joint fusion, called fusing tarsitis.
Calcaneo-cuboid osteoarthritis can be associated with talo-navicular osteoarthritis. Calcaneal fractures can cause calcaneo-cuboid osteoarthritis when the fracture lines involve this joint.
Osteoarthritis of the Hindfoot
Osteoarthritis of the hindfoot refers to osteoarthritic involvement of the subtalar joint, formed by the talus and calcaneus. This joint is much less mobile than the ankle, is particularly stressed on uneven ground, and allows adaptation of the foot's position on irregular terrain. Its action is combined with that of the ankle.
Fractures of the talus and calcaneus are particularly arthrogenic for the subtalar joint when they are articular.
Recurrent sprains of the ankle may lead to chronic ankle instability associated with instability of the subtalar joint. This subtalar instability carries a potential risk of osteoarthritis.
Ankle Osteoarthritis
Evaluation of the ankle is important in cases of foot osteoarthritis, particularly in the subtalar joint. Subtalar stiffness causes increased joint stress at the ankle.
Osteoarthritis of the Big Toe or Hallux Rigidus
Metatarsophalangeal osteoarthritis of the first ray, or big toe osteoarthritis, also known as hallux rigidus, is a common condition in the forefoot. Significant trauma to the first ray's metatarsophalangeal joint is a risk factor for hallux rigidus, but the presence of a long first metatarsal and repeated microtraumas are also causes of osteoarthritis.
What are the possible treatments?
Treatment is first and foremost symptomatic. It involves resting the arthritic joint if it is painful, and taking painkillers and anti-inflammatories.
Functional treatment consists of wearing splints to limit joint movement, or using insoles with stiffening or mechanical pressure correction elements to relieve the affected joints.
If medical treatment is insufficient and disability persists, surgical treatment of the arthritic joint may be considered.
What operations are possible?
Surgical interventions that may be proposed depend on the location of the osteoarthritis and the joint involved.
For the joints of the forefoot, prosthetic replacement must be weighed against foot arthrodesis, which consists of the fusion of the affected joints. The advantage of prosthetic replacement is the preservation of residual adaptive mobility, allowing adjustment to uneven terrain and changes in slope. It also increases the options for footwear.
For the midfoot joints, there is no prosthetic replacement for the talonavicular and calcaneocuboid joints. In the case of osteoarthritis affecting these joints, an arthrodesis may be proposed. Regarding the Lisfranc joints, in the case of osteoarthritis of the mobile lateral Lisfranc, it is possible to perform a spherical pyrocarbon arthroplasty, allowing preservation of the articular mobility of the lateral Lisfranc. The medial Lisfranc may be arthritic and treated in various ways, by performing an arthrodesis or a resection arthroplasty. The cuneometatarsal joint of the first ray is fused in case of osteoarthritic lesion.
In the hindfoot, there is no prosthesis for the subtalar joint; in case of joint damage, an arthrodesis may be proposed.
FAQ
Osteoarthritis is known as a degenerative disease, meaning it results from wear and tear. The wearing down of cartilage may be accelerated by traumas such as fractures or sprains. Chronic inflammatory diseases also cause cartilage damage. Therefore, there is no natural way to cure osteoarthritis. The therapeutic goal is to treat lesions that could potentially cause osteoarthritis in order to reduce the risk of its onset or slow its progression.
Symptomatic treatment of osteoarthritis is always considered. It involves resting the joint and taking painkillers and anti-inflammatory medications. Wearing orthotics, splints, or orthopedic insoles can help relieve osteoarthritis of the foot. The methods used depend on the location of the osteoarthritis.
Wearing shoes with rather rigid soles can help limit the range of motion in the joints of the foot. For osteoarthritis of the midfoot and hindfoot, wearing high-top shoes also helps to limit mechanical stress on the joints.