Imaging Quiz Answer
Forefoot Pain in a Young Girl
Kenneth R. Veenema, MD
THE PHYSICIAN AND SPORTSMEDICINE - VOL 27 - NO. 1 - JANUARY 1999
The following findings on the plain radiograph (figure 2) are consistent with a diagnosis of Freiberg's infraction: flattening of the third metatarsal head with peripheral fragmentation of the articular surface, resulting in a lateral loose body; central subchondral radiolucency, suggesting osteolysis; and preservation of the cylindrical shape of the metatarsal head.
The patient was treated for 4 months with an extended steel shank placed in her shoe to limit metatarsophalangeal joint loading during daily weight bearing. She avoided running and jumping during gym and sports but was allowed to swim and bicycle.
At the 4-month follow-up, she was asymptomatic, and repeat plain radiographs (figure 3) showed interval resolution of the subchondral osteolytic lesion with preservation of the cylindrical shape of the third metatarsal head consistent with healing. She began to wear regular shoes for gradually longer periods and slowly resumed impact activities.
Freiberg's infraction is an uncommon disorder of the forefoot seen predominantly in active adolescent girls. It is an articular osteochondrosis that occurs most commonly in the second metatarsal head, with the third metatarsal head the next most frequent location (1).
Etiology. As with other osteochondroses, the cause of the disorder is controversial. The debate has centered on whether the condition is a result of traumatic injury to the articular surface or of vascular insult to the metatarsal head. More than likely, several factors contribute to the development of the disorder, including excessive pressure on the metatarsal head, repetitive microfractures, loss of blood supply to subchondral bone, synovitis, and limitation of motion. Such a multifactorial etiology has had much support (2).
Signs and symptoms. The symptoms of Freiberg's infraction, like those of metatarsal stress fractures, include vague forefoot pain that worsens with load-bearing impact activities such as running and jumping. Patients may or may not recall a specific traumatic event. They may be relatively asymptomatic for long periods, only to have the pain recur after a stressful event—such as wearing the first pair of high heels—or subsequent reinjury.
Early physical findings include localized tenderness over the involved metatarsophalangeal joint, pain and crepitation with motion of the joint, and mild periarticular soft-tissue swelling. Late physical findings reflect degenerative changes in the joint and include pain, loss of motion, and palpable osteophytes (3).
Radiographic findings. Radiographs taken early in the course of the disorder are often negative. If this is the case, but the lesion is suspected because of the patient's history, age, and sex, an early bone scan or magnetic resonance image (MRI) should be considered to differentiate the condition from the more common metatarsal stress fractures. This would allow treatment for Freiberg's infraction to begin earlier and possibly prevent deformation of the metatarsal head.
Early radiographic evidence of advancing pathology includes flattening of the dorsal aspect of the metatarsal head and subchondral osteolysis. As the process progresses, the dorsal central portion of the articular surface collapses because of osteonecrosis of the underlying bone, and osteophytes form along the medial and lateral margins of the metatarsal head. The osteophytes can fracture and cause loose bodies. End-stage degenerative changes, marked by a severely flattened metatarsal head, subchondral sclerosis, and joint space narrowing, are generally irreversible and make activities such as running and jumping very painful.
The prognosis and the extent of the physical complaints do not necessarily correlate with the extent of the radiographic changes. Multiple classification schemes based on the radiologic changes have been described, but none has been shown to correlate consistently with prognosis or treatment.
Treatment. Preservation of the cylindrical shape of the metatarsal head is a goal of treatment and can be followed radiographically. Early stages of the disease, ie, before collapse of the joint surface and formation of osteophytes, are treated with initial immobilization in a short leg cast and limited weight bearing, followed by progressive weight bearing with shoe modifications such as an extended steel shank insert to protect and limit motion of the involved metatarsophalangeal joint. An alternative to a short leg cast is a removable short leg cast boot, which allows the patient to begin a non-weight-bearing strength-maintenance program during this phase of treatment.
Patients may resume high-impact activities progressively as tolerated. The rate at which they do so will vary and must be based on pain-free exam and ambulation and on radiographic evidence of healing, ie, ossification of the osteolytic lesion and no progression of metatarsal head deformation (4).
If conservative measures fail, surgery is warranted. Various surgical methods have been described, including joint debridement with removal of osteophytes and loose bodies, metatarsal head excision, metatarsal head osteotomy, and joint replacement (5). No single procedure has produced uniformly good results. Recent trends indicate that arthroscopic treatments may have a role in the future (6).
As the cause of Freiberg's infraction remains unclear, there is no evidence to support any specific means of prevention. The goal of diagnosis and treatment is to arrest the condition as early as possible. This requires a high index of clinical suspicion in at-risk individuals and early recognition of the lesion through the use of bone scan or MRI if initial radiographs are negative.
Dr Veenema practices at University Sports Medicine in Rochester, New York, and is an assistant professor of emergency medicine and orthopaedics in the Department of Emergency Medicine and Orthopaedics in the Division of Athletic Medicine at the University of Rochester School of Medicine. Address correspondence to Kenneth R. Veenema, MD, University Sports Medicine, 2180 S Clinton Ave, Rochester, New York 14618.