Determining X-ray Plate Position on Lateral Foot Radiographs
On a properly positioned lateral foot radiograph, you can determine plate placement by evaluating metatarsal head overlap: when the plate is under the 5th toe (medial-side-down positioning), the 5th metatarsal head appears most plantar with progressive dorsal stacking of the other metatarsal heads, whereas plate-under-great-toe positioning (lateral-side-down) shows the 1st metatarsal head most plantar.
Key Radiographic Indicators
Metatarsal Head Alignment Pattern
5th toe down (medial-side-down): The 5th metatarsal head projects most inferiorly/plantarly on the image, with the 4th, 3rd, 2nd, and 1st metatarsal heads progressively stacking dorsally in that order 1, 2
Great toe down (lateral-side-down): The 1st metatarsal head appears most inferior/plantar, with the 2nd through 5th metatarsal heads progressively stacking dorsally 1, 2
Additional Confirmatory Features
Sesamoid visualization: When the great toe is down (lateral-side-down), the hallux sesamoids are typically better visualized and more clearly separated on the lateral projection 3
Tibiotalar relationship: Standard lateral foot radiographs should demonstrate proper tibiotalar alignment regardless of positioning, but the overall foot architecture helps confirm orientation 3
Clinical Context and Standard Positioning
Conventional Technique
Standard lateral foot radiographs are typically obtained with the medial side down (5th toe against the plate), which is the most common positioning for routine foot imaging 3
This positioning allows for consistent evaluation of standard lateral measurements including the talocalcaneal angle, talus-first metatarsal angle, and talohorizontal angle 1, 2, 4
Why This Matters
Measurement accuracy: Many standard radiographic angles and reference points depend on consistent positioning for reliable interpretation 1, 2
Comparison studies: Serial radiographs should use identical positioning to allow accurate assessment of progression or treatment response 2
Weight-bearing views: When weight-bearing lateral radiographs are obtained (particularly for Lisfranc injuries or hallux MTP joint evaluation), consistent positioning is essential for detecting subtle malalignment 3
Common Pitfalls to Avoid
Assuming positioning without verification: Always verify metatarsal head stacking pattern before making measurements or clinical decisions based on lateral foot radiographs 1
Inconsistent positioning for serial studies: Ensure follow-up radiographs use the same positioning as baseline studies to allow meaningful comparison 2
Overlooking rotation: True lateral positioning requires all five metatarsal heads to be superimposed or minimally separated; excessive separation indicates obliquity rather than true lateral positioning 1, 2