Japanese researchers shed light on ankle pain in soccer injuries

The growing worldwide popularity of soccer means that more radiologists are encountering injuries. Understanding the biomechanics of each injury, particularly in the ankle, enables them to make a more accurate diagnosis and recommend the most appropriate treatment, according to an educational exhibit presented at the RSNA meeting.

Soccer is played regularly by over 200 million men and 21 million women, and injuries are common. Between 1993 and 2003, there were 2168 injuries in 2586 professional games in Japan. The most common site of injuries was the lower extremities (65%), followed by the face (18.3%), body trunk (8.9%), and others (7.8%).

"Facial injuries happened frequently during the initial startup of the professional league. This may have been due to overly aggressive contact play, leading to head clashes," said Dr. Yoshikazu Okamoto, a radiologist from the Institute of Clinical Medicine, University of Tsukuba, in Japan.

Contusion, sprain, and muscle strain were the most common kinds of injury. Sprains occurred most often in the ankle joint (66%), while muscle strains were most common in the thigh (79.2%).

Most ankle sprains occur in the lateral ligament, which can be injured by inversion (supination, adduction, and plantar flex). Usually, the anterior talofibular (ATF) ligament gets injured first, and then the calcaneofibular (CF) ligament is injured by forcible inversion. The posterior talofibular (PTF) ligament is rarely injured.

"The key diagnostic task in MRI is to identify ATF and CF ligaments," Okamoto said. "The injured site is swollen and becomes hyperintense on T2-weighted images, reflecting focal edema. A bruised talus can be seen in more complicated cases. Injured ligaments are thickened when the injury is chronic."

Impingement exostosis, or so-called footballer's ankle, is often seen in older players and those competing at a higher level. Repeated marked dorsiflexion of the ankle joint during jumping and sprinting can cause these injuries. Osteochondral injury at the anterior aspect of the ankle joint occurs due to frequent crashes between the antero-lower pole of the tibia and the neck of the talus, producing reactive osteophytosis.

Plain radiographs show osteophytes at the anterior inferior side of the tibia and dorsal aspect of the neck of the tibia, but they can occur at the medial or lateral side of the tibia.

Os trigonum is a supernumerary bone seen in the posterior portion of the foot that is formed from remnants of the epiphyseal nucleus or fragments of the posterior eminence of the talus. Repeated motor stimulation can induce pain, causing os trigonum syndrome. Plain radiographs can clearly demonstrate os trigonum at the posterior inferior side of the talus.

Stress fractures that occur in soccer are mostly in the metatarsal bones, especially from the center to the distal portion of the second or third bone. "Jones' fracture," which is a fracture of the proximal portion of the fifth metatarsal, is also common. Other affected sites include medial malleolus, navicular bone, talus, and calcaneus.

These fractures usually heal in one to two months, provided the player rests. But because Jones' fractures often recur, surgical treatment, including medullary screwing, bone grafting, and plate fixation, may be necessary.

"Usually plain radiographs can reveal stress fractures," Okamoto said. "Findings include a radioluscent area of the cortex, periosteal reaction, and focal osteosclerosis. These features are not always seen in the early stage of the fracture but are sometimes recognized after a week. CT and MRI can also contribute to the early diagnosis and follow-up."