Is soft-tissue inflammation in pedal infection contained by fascial planes? MR analysis of compartmental involvement in 115 feet.

OBJECTIVE

The purpose of this study was to analyze compartmental involvement and patterns of spread of soft-tissue inflammation in pedal infection.

MATERIALS AND METHODS

We reviewed 115 contrast-enhanced 1.5-T MR examinations of the foot in 41 women and 74 men with a mean age of 58.4 years who had undergone bone biopsy or surgery for suspected osteomyelitis. Presence of inflammation (contrast enhancement, fat signal intensity loss on T1-weighted images, and high signal intensity on T2-weighted images) was noted by two musculoskeletal radiologists in the following foot compartments: toes, medial, central, lateral, interosseous, dorsal, hindfoot, malleoli, and lower leg. Proximal and distal extension of soft-tissue inflammation was analyzed. The compartment closest to the ulcer that showed MR signs of direct contiguous infection was designated the primarily infected compartment.

RESULTS

Spread of inflammation across fascial planes into neighboring compartments originated from the following primary compartments: medial (3/10, 30%), central (7/16, 44%), and lateral (16/20, 80%). Spread from the hindfoot and malleoli into adjacent compartments was seen in only 7% of such cases (2/24). Inflammation from toe infections spread in 34% of cases to forefoot compartments (15/44). Inflammation from forefoot or toe infections spread in 4.5% of cases to the midfoot and in 2% of cases to the hindfoot; ascension into the calf was rare (1% of cases). Spread of inflammation into neighboring compartments was not correlated with the presence of diabetes (p = 0.81) or with osteomyelitis (p = 0.34).

CONCLUSION

Soft-tissue inflammation of the forefoot tends to spread into neighboring compartments, with little respect for fascial planes. Hindfoot inflammation tends to stay confined. Spread from the foot to the lower leg is rare.