Osteoarthritis of the Subtalar Joint

Osteoarthritis of the subtalar joint is a degenerative condition affecting the joint between the talus and calcaneus, located just below the ankle. The subtalar joint allows the foot to move from side to side and helps the foot adapt to uneven surfaces while walking. When the cartilage within this joint becomes damaged or wears away, the bones can rub against each other, causing pain, stiffness, swelling, and reduced mobility.

Subtalar arthritis is frequently associated with previous injuries, particularly fractures involving the heel bone. Although it is less common than arthritis of the knee or hip, it can significantly affect walking, standing, exercise, and other daily activities.

Causes

Subtalar osteoarthritis most commonly develops after an injury to the joint. This is known as post-traumatic osteoarthritis and can occur following a calcaneal fracture, talus fracture, severe ankle or foot sprain, or another injury that damages the joint surface or changes normal alignment.

Trauma can directly injure the cartilage and alter the way forces are distributed through the subtalar joint. Over time, abnormal loading contributes to progressive cartilage loss, narrowing of the joint space, bone spur formation, and stiffness.

Subtalar arthritis can also develop without a specific injury. Age-related degeneration, chronic abnormal foot mechanics, deformity, inflammatory arthritis, and repetitive stress may contribute to cartilage deterioration. Athletes, laborers, military personnel, and others who regularly participate in high-impact activities may place additional stress on the joint.

Anatomy

The subtalar joint connects the talus, which sits beneath the ankle joint, with the calcaneus, which forms the heel. Unlike the ankle joint, which primarily allows the foot to move up and down, the subtalar joint is responsible for much of the foot’s inversion and eversion.

These side-to-side movements allow the foot to adapt to uneven terrain and absorb forces during walking and running. Strong ligaments and surrounding muscles help stabilize the joint, while smooth cartilage allows the joint surfaces to move with minimal friction.

When cartilage is damaged, normal joint motion becomes painful and progressively restricted. Advanced arthritis can cause substantial loss of subtalar motion and alter the mechanics of the entire foot.

Symptoms

Symptoms often develop gradually and may become more noticeable with prolonged walking or standing. Patients commonly experience deep, aching pain in the heel or outer portion of the rearfoot. Pain may be particularly pronounced when walking on uneven ground, going up or down slopes, or turning the foot from side to side.

Common symptoms include:

·   Pain below or behind the ankle

·   Stiffness of the rearfoot

·   Swelling or tenderness around the subtalar joint

·   Difficulty walking on uneven surfaces

·   Reduced ability to move the foot from side to side

·   Pain with prolonged standing or walking

·   A feeling of instability or weakness

·   Progressive difficulty participating in recreational or athletic activities

As arthritis progresses, patients may compensate for restricted subtalar motion by changing the way they walk. This can increase stress on other areas of the foot and ankle and contribute to additional pain.

Diagnosis and Imaging

Diagnosis begins with a medical history and physical examination. We assess the location of pain, foot alignment, swelling, stability, and range of motion. Particular attention is given to subtalar motion because restriction or pain with inversion and eversion can help identify the joint as the source of symptoms.

Weight-bearing X-rays are generally the first imaging study used to evaluate subtalar arthritis. They can demonstrate narrowing of the joint space, bone spurs, sclerosis, deformity, and changes in alignment.

A weight-bearing CT may provide a more detailed assessment of the joint surfaces and is particularly useful in patients with previous fractures or complex deformities. MRI may be recommended when cartilage damage, bone marrow changes, tendon problems, or other soft-tissue conditions need to be evaluated.

Nonsurgical Treatment

Treatment initially focuses on controlling pain, reducing stress on the joint, and maintaining as much function as possible. The appropriate treatment depends on the severity of arthritis and the patient’s activity level.

Nonsurgical options may include:

·   Activity modification: Reducing high-impact activities such as running and jumping can decrease stress on the subtalar joint. Low-impact activities such as swimming or cycling are often better tolerated.

·   Supportive footwear: Shoes with a stable sole can reduce painful motion and improve overall foot mechanics.

·   Orthotics: Custom or prefabricated orthotics may help control alignment and redistribute pressure through the foot.

·   Physical therapy: Exercises can improve strength, flexibility, balance, and gait mechanics while maintaining mobility in surrounding joints.

·   Medications: Anti-inflammatory medications may help control pain and inflammation when medically appropriate.

·   Injections: A corticosteroid injection into the subtalar joint may provide temporary pain relief and can also help confirm that the subtalar joint is the primary source of symptoms.

Nonsurgical treatment can often control symptoms in mild to moderate arthritis, although it does not reverse established cartilage loss.

Surgical Treatment

Surgery may be considered when persistent pain and functional limitations remain despite appropriate nonsurgical treatment or when there is advanced joint destruction.

Subtalar arthrodesis, or fusion, is the most established surgical treatment for severe isolated subtalar arthritis. During fusion, the damaged cartilage is removed and the talus and calcaneus are stabilized together so that the bones heal as one. Eliminating motion at the arthritic joint reduces the mechanical source of pain. Patients lose subtalar motion, but many can walk comfortably after healing.

Other procedures may be appropriate in selected patients. Arthroscopic debridement can remove loose cartilage, inflamed tissue, or bone spurs in carefully selected cases with less advanced disease. Corrective osteotomy may be performed when abnormal alignment is contributing to uneven joint loading. Subtalar joint replacement is less commonly used and remains a specialized option for select patients.

The surgical approach is determined by the degree of arthritis, alignment, previous injuries, bone quality, and functional goals.

Recovery and Rehab

Recovery depends on the treatment performed. Patients treated nonsurgically may notice improvement over several weeks with consistent use of supportive footwear, orthotics, activity modification, and physical therapy.

Recovery after subtalar fusion generally involves a period of restricted or non-weight-bearing activity while the bones heal. Patients are typically transitioned from a cast to a walking boot and gradually progress weight-bearing based on clinical and imaging findings. Physical therapy may be used to restore strength, balance, and gait mechanics.

Recovery after fusion can take several months, with continued improvement as swelling decreases and strength returns. Because the subtalar joint no longer moves after fusion, some patients notice difficulty adapting to uneven terrain, although many return to comfortable daily walking.

Potential Complications

Potential complications of subtalar arthritis and its treatment include persistent pain, stiffness, infection, nerve irritation, nonunion after fusion, and continued symptoms from arthritis in neighboring joints.

Because fusion eliminates subtalar motion, increased stress may be transferred to other joints of the foot over time. Patients with replacement procedures may also experience implant loosening, wear, or failure. The risk of complications varies according to the procedure, underlying condition, bone quality, smoking status, and other individual factors.

Long-Term Outlook

The long-term outlook depends on the severity of arthritis and the underlying cause. Early management can reduce symptoms and help maintain function, although damaged cartilage does not regenerate. Patients with advanced arthritis who undergo subtalar fusion generally experience substantial and lasting pain relief when the joint successfully heals.

Maintaining a healthy weight, using appropriate footwear, managing activity levels, and addressing foot alignment can help reduce stress on the subtalar joint. Prompt treatment of significant foot and ankle injuries may also reduce the risk of developing post-traumatic arthritis.

When to See a Specialist

Persistent pain below the ankle, particularly pain that worsens on uneven surfaces or limits walking and exercise, should be evaluated by a foot and ankle specialist. Early assessment can identify subtalar arthritis and distinguish it from other causes of rearfoot pain, including sinus tarsi syndrome, peroneal tendon disorders, tarsal coalition, posterior tibial tendon dysfunction, and other forms of foot arthritis.

At Complete Orthopedics, our foot and ankle specialists evaluate subtalar arthritis using a combination of clinical examination and appropriate imaging. Treatment is tailored to the severity of disease and each patient’s functional needs, with an emphasis on controlling pain and preserving mobility whenever possible.