Harris-Beath projection

Harris-Beath projection

radiographic projection of the foot, to visualize rearfoot and tarsus; the patient is positioned with the foot flat to the support surface, ankle joint dorsiflexed and knees flexed (as if preparing for a standing jump); the X-ray beam is directed at the posterior aspect of the ankle joint, at an inclination angle of 35-45° (see Table 1)
Table 1: Common radiographic projections of the foot and ankle
ProjectionVisualization
Foot projections
Dorsiplantar (DP) projection or anteroposterior (AP) viewWeight-bearing with the beam directed at 15° to the frontal plane, to eliminate distortion due to the angulation of the metatarsals and centred on the metatarsal shafts
It is used to visualize the phalanges, metatarsophalangeal joints, the metatarsals and the midfoot
Lateromedial oblique projectionWeight-bearing with the beam angled at 45° to the lateral side of the sagittal plane and centred on the forefoot; or non-weight-bearing, with the beam vertical and foot everted so that the plantar surface is at 45° to the ground surface
It is used to visualize the phalanges, metatarsals, metatarsocuneiform joints and sesamoids, but tends to give an elongated image of bony architecture
Mediolateral oblique projectionWeight-bearing with the beam angled between 25 and 45° to the medial side of the sagittal plane and centred on the forefoot
It is used to visualize the first ray and associated structures, but tends to give an elongated image of bony architecture
Lateral projectionWeight-bearing or non-weight-bearing, with the beam angled at 90° to the lateral aspect of the foot and centred on the mid- or hindfoot
It is used to visualize the profile of the whole foot, but obscures the midtarsal joint, due to superimposition of local structures
Digital projectionThe lateromedial oblique projection is useful to visualize subungual exostoses, especially when the hallux (or affected toe) is raised up on a pad
Sesamoid projection or skyline projectionWeight-bearing, with the metatarsophalangeal joints dorsiflexed to 45° and the beam angled to be parallel to the ground surface on the sagittal plane, and centred on the plantar aspect of the forefoot
It is used to visualize the relationship of the sesamoids with the head of the first metatarsal
Tarsal and ankle projections
Anteroposterior viewWeight-bearing with the beam angled at 90° to the frontal plane and the beam centred on the ankle joint
Used to visualize the ankle mortise and the trochlear surface of the talus
Axial calcaneal projectionWeight-bearing with the beam angled at 45° to the posterior aspect of the sagittal plane with the beam centred on the hindfoot
It is used to visualize calcaneal trauma
Harris-Beath projectionSimilar to the axial calcaneal projection, but the patient is positioned as if making a ski-jump, that is, weight-bearing with the foot dorsiflexed at the ankle and the beam angled at 45° to the posterior aspect of the sagittal plane with the beam centred on the ankle
It is used to visualize the subtalar joint where talar fusions are suspected
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