Terminology
The Lamellar Lucent Zone (LLZ) is the less radiopaque layer visible between the distal phalanx and the more radiopaque outer portion of the hoof wall. Magnetic resonance comparison has associated this radiographic region with lamellar and sublamellar tissues.
“Lamellar Lucent Zone” is the terminology used by Skelton and colleagues in their Equine Veterinary Journal study. DigiHoof uses that name in the clinical interface and reports.
Image technique
LLZ measurement requires appropriate acquisition and post-acquisition review. Confirm:
- Correct lateromedial or dorsopalmar projection
- Appropriate positioning and beam alignment
- Diagnostic exposure and windowing
- Visibility of the dorsal P3 and hoof-capsule margins
- Valid calibration
- Correct laterality and marker placement
Absolute LLZ width is affected by magnification and obliquity. Skelton and colleagues reported that the evaluated LLZ ratios were less affected by those factors in their study.
Lateromedial outputs
DigiHoof can calculate:
- Proximal LLZ width
- Middle LLZ width
- Distal LLZ width
- Palmar cortical length of P3 (PCL)
- LLZmid:PCL
- Level-specific LLZ:DHW-Pd ratios
- Inner and outer hoof wall–P3 angles
- Sole depth
The proximal, middle, and distal LLZ widths are calculated perpendicular to the dorsal P3 reference axis using the final veterinarian-approved landmarks.
Dorsopalmar outputs
The dorsopalmar workflow can report:
- Medial and lateral LLZ width
- Medial and lateral hoof-wall width
- Medial and lateral sole depth
Side-to-side values require careful review of rotation, obliquity, and marker placement.
Evidence and limitations
Skelton and colleagues evaluated 126 radiographs classified as acute, subacute, or control and reported differences in LLZ widths and selected ratios between groups. Magnification and obliquity affected absolute LLZ measurements in the serial technique assessment. The study did not include histologic confirmation of laminitis.
The reported cohort thresholds are literature context, not a substitute for diagnosis. LLZ values must be interpreted with the clinical examination, history, image technique, and other radiographic findings.
DigiHoof proposes landmarks and performs deterministic calculations from the final point geometry. The veterinarian must correct inaccurate landmarks and decide whether each output is valid for the case.
