Foot Pathology: Arthritis

Osteoarthritis of the foot
The detection of osteoarthritis (OA) of the foot is another indication where CT is superior to conventional radiographs. In the foot, osteoarthritis affects the areas where maximal weight bearing occurs, and can also arise in a joint affected by trauma.

Within the foot, certain joints are predisposed to OA. The first metatarsal-phalangeal joint is one (Figure: OA of the 1st MTP), and osteophytes commonly arise dorsally and laterally. Other manifestations include hallux rigidus (limited 1st toe dorsiflexion) and hallux valgus (pronation of the 1st toe in conjunction with medial 1st metatarsal head osteophytes). The 2nd through 5th metatarsal phalangeal joints are less commonly involved; the first interphalangeal joint may be affected.

The tarsal-metatarsal and intertarsal joints can also be affected by OA. Midfoot osteoarthritis may be the sequela of trauma or surgical fusion and can arise in the setting of tarsal coalition. In the hindfoot, Resnick and Berquist describe involvement of the “talonavicular portion anterior talocalcaneonavicular joint” as classic for OA, generally the sequela of trauma.

Radiographic findings on CT (Figure: OA of the foot) are the same as those detected by conventional radiographs, including subchondral sclerosis, asymmetric or nonuniform joint space narrowing, osteophytes, subchondral cysts, and in some cases osteocartilaginous intrarticular fragments. In addition, plantar and posterior calcaneal spurs are manifestations of degenerative joint disease; although, they are often asymptomatic.

Osteoarthritic changes in the talus can also be seen in degenerative joint disease of the ankle. In addition to the classic findings, a talar beak may be seen (Figure: talar beak in OA). This is distinct from the beak of tarsal coalition in its location (posterior to the talonavicular joint) and in its association with other findings of osteoarthritis.

Osteoarthritis of the ankle.
Degenerative arthritis of the ankle can complicate tarsal coalition. However, ankle OA is not as common as OA of the foot unless the patient has had trauma or other disease processes which predispose to osteoarthritis.

Diagnosis: Osteoarthritis.
Diagnosis: Calcaneal spur.
Diagnosis: Calcaneal spur.
Diagnosis: Calcaneal spur.
Diagnosis:Osteoarthritis of the tarsal bones.
Diagnosis: Osteoarthritis
Diagnosis:Osteoarthritis
Clinical History: 67 year old man with chronic, debilitating pain. CT Findings: Subcondral sclerosis and osteophyte formation of the talocalcaneal joints. Talonavicular osteoarthritic changes were also noted. No fracture. Osteoporosis of the bones of the left foot. Diagnosis: Talonavicular and talocalcaneal osteoarthritis. Outcome: MRI showed degenerative changes of the talo-calcaneal joint with subchondral bone edema, as well as talonavicular osteophytes. In addition, fluid was noted around the posterior tibialis tendon suggesting synovitis, and edema was identified around the os trigonium.
Clinical History: CT demonstrates narrowing of the joint space between talus and calcaneus , with sclerotic changes on both sides of the joint space. Large osteophytes of the tibia and osteoporosis are seen. Patient had severe ankle pain and difficulty walking. CT Findings: CT demonstrated significant degenerative change in the ankle joint with large osteophytes of the tibia and osteoporosis seen. Diagnosis: Narrowing of the joint space between talus and calcaneus was seen with sclerotic changes on both sides of the joint space.
Clinical History: 8 year old boy with pain. CT Findings: Talo-calcaneal subchondral sclerosis with small osteophytes. No fracture. Mild osteoporosis is noted. Diagnosis: Subtalar osteoarthritis and osteoporosis. Comments: The patient has a history cerebral palsy.