Revealing radiographs: Foot and ankle biomechanics

An illustration of foot/ankle bony abnormalities

Abnormal biomechanics of the foot/ankle can be deceptive. Radiographs frequently reveal patients’ lifestyle, stresses, prior trauma and diseases. Following trauma, X-rays of the foot and ankle are essential. Clinical findings of a rigid foot and ankle with joint restrictions, known or suspected anomalies, deformities and misalignments are justifiable reasons to perform an X-ray examination.

To devise an appropriate treatment plan or referral, doctors of chiropractic must gather the patient’s history, thoroughly evaluate orthopedic and neurological conditions and use relevant imaging such as X-rays. Another source of imaging is computerized foot scans to further assess the foot. 

This article illustrates foot/ankle bony abnormalities. These cases are examples of congenital anomalies, repetitive stress and degenerative changes, which are indicators of altered biomechanics of the foot/ankle. These changes can also influence the biomechanics of the extremities above the foot and ankle, pelvis and spine.  

Case 1

Image A. Image courtesy of radiopaedia.org 

The oblique X-ray consists of pseudoarthrosis or coalition at the calcaneonavicular articulation, which is a congenital anomaly. This finding typically results in a rigid foot/ankle.  

 

Image B. Courtesy of radiopaedia.org 

The lateral X-ray consists of another congenital anomaly with bony bar or coalition at the posterior talocalcaneal articulation. There is associated talar beaking (bony prominence) along the dorsal aspect of the anterior talus, and mild osteoarthritis at the talonavicular joint. Other findings are minimal enthesophyte at the plantar calcaneal attachment of the plantar fascia/aponeurosis. The talocalcaneal coalition also results in a rigid foot/ankle. 

 

Case 2

Image C. Courtesy of physio-pedia.com 

The first metatarsal bone is congenitally shortened, resulting in the appearance of elongated second toe. Morton’s Toe or syndrome can result in hypermobility and instability of the first metatarsal bone, increased pressure and stress on the second metatarsal bone, and may cause overpronation of the foot.  

 

Case 3

Image D. Courtesy of radiopaedia.org 

The dorsoplantar and oblique X-ray consists of callous formation within the mid diaphysis of the second metatarsal bone, consistent with a stress fracture. A stress fracture is not initially detected on an X-ray until callous formation is seen at the fracture site and may take 2-4 weeks to appear. For early and accurate detection, magnetic resonance imaging (MRI) of the foot is recommended. MRI detects stress fractures as high signal bone marrow edema. CT and X-rays are not as sensitive as MRI for early detection of stress fractures.  

 

Image E. Courtesy of radiopaedia.org 

On the lateral radiograph, linear sclerosis perpendicular to the trabecular lines of the posterior calcaneus is an indicator of a stress fracture of the calcaneus. 

Stress fractures are defined as abnormal stress placed on bone with normal bone density and are typically due to repetitive compressive loading. If stress fracture is clinically indicated and not obvious on the X-ray, MRI could be performed to detect the stress fracture with a small area of low signal surrounded by high signal of marrow edema. 

 

Case 4

Image F. Courtesy of istockphoto.com 

The lateral X-ray consists of enthesophyte formation at the posterior calcaneal attachment of the Achilles tendon and at the plantar calcaneus. 

An enthesophyte is abnormal bony outgrowth or osteophyte within the entheses, a connective tissue between bone and tendon or ligament. Enthesophyte formation is due to overuse, abnormal stress and biomechanics, infection and inflammatory conditions and may indicate an unhealthy tendon. Plantar fasciitis or Achilles tendinopathy can be evaluated by MRI.  

 

Case 5

Image G. Courtesy of radiopaedia.org 

On the DP X-ray hallux valgus deformity is apparent at the first metatarsophalangeal joint with lateral deviation of the sesamoid bones and adjacent soft tissue fullness. Mild narrowing, sclerosis and osteophyte formation are also observed. Varus deformity is noted at the fifth metatarsophalangeal joint appearing as a bunion deformity of the first toe and bunionette of the fifth toe. The bunion deformity can be caused by poorly fitting shoes, heredity or inflammatory or neuromuscular conditions.  

Final thoughts

In conclusion, these cases show bony abnormalities associated with or the result of altered biomechanics of the foot/ankle. Chiropractic treatment cannot change the bony abnormalities but can improve, manage or maintain function. A custom orthotic that supports all three arches of the foot can be considered in the event of assessing and treating for stabilization. Radiographs and other imaging such as a computerized foot scanner is informative in assessing and confirming the biomechanics of the foot and ankle. It is also crucial to evaluate the remaining extremities, pelvis and spine for compensation, muscular and neurological imbalances, and joint dysfunction to implement appropriate treatment, referral and advanced imaging.  

JENNIFER PEDLEY, MS, DC, DACBR, graduated from Northwestern Health Sciences University with a doctor of chiropractic degree. Several years after having a private practice, she continued her education at National University of Health Sciences to complete the radiology residency. She has a private radiology reading practice in Redlands, Calif., and enjoys reading X-rays and MRI of the spine and extremities. She also lectures for various continuing education organizations such as Foot Levelers and state associations.