Tendon involvement in pedal infection: MR analysis of frequency, distribution, and spread of infection.

OBJECTIVE

The objective of our study was to evaluate the frequency, distribution, and extent of tendon involvement in patients with pedal infections.

MATERIALS AND METHODS

Contrast-enhanced MR imaging examinations of 159 infected feet performed at 1.5 T were reviewed by two musculoskeletal radiologists for the presence and location of tendon infection (peritendinous enhancement contiguous to an adjacent ulcer or cellulitis) and for the spread of infection along tendons, which was defined as peritendinous contrast enhancement extending more than 2 cm beyond surrounding cellulitis. The study group was composed of 156 consecutive patients, 82.7% of whom had diabetes; all patients underwent subsequent surgical treatment. Results of MR evaluations were compared with the patients' charts and surgical reports.

RESULTS

Of the 129 MR examinations showing an infection in the forefoot, MR evidence of tendon involvement in the infection was observed in 56 MR examinations (43%). The sum of involved tendons per ray was as follows: first ray (flexor tendon, n = 19; extensor tendon, n = 13), second (flexor tendon, n = 12; extensor tendon, n = 7), third (flexor tendon, n = 5; extensor tendon, n = 4), fourth (flexor tendon, n = 5; extensor tendon, n = 1), and fifth (flexor tendon, n = 11; extensor tendon, n = 6). Of the 32 MR examinations showing infection in the hindfoot, 14 examinations (44%) showed evidence of tendon involvement, most frequently of the distal Achilles tendon (n = 7). MR evidence of the spread of infection along a tendon was seen in 12 examinations, always with proximal spread of infection; and infection led to the development of an abscess in the central plantar compartment in three patients. Intraoperative evidence of a tendon infection was documented in 11 patients. The surgical procedure was altered because of the tendon infection in six patients.

CONCLUSION

MR evidence of tendon infection is present in approximately half the patients who require surgery for pedal infection. Evidence of spread of the infection along tendons is seen infrequently on MR imaging. Detection of a tendon infection could influence surgical therapy.