[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Forensic medicine](https://durgical.com/en/forensic-medicine/) › [Mechanical injuries](https://durgical.com/en/forensic-medicine/areas/injuries/) › Patterned injuries: what the mark says about the object

# Patterned injuries: what the mark says about the object

- Finding

A patterned injury copies the shape of the object or surface that caused it, and can link a wound to a weapon, a shoe or a vehicle.

Updated Nov 13, 2026

## Key points

- Rod or stick: two parallel linear bruises with pale skin between («tramline» bruise).
- Shoe: sole pattern from a stamp or kick; the tread may be compared with a specific shoe.
- Grip: round or oval fingertip bruises in groups on arms, neck or thighs; fingernail marks as small curved abrasions.
- Hammer: round or square depressed skull fracture or scalp wound matching the face.
- Patterned mark on the abdomen or chest from a seat belt, handlebar or tyre also shows the force involved.

On this page

- The basics Key points
- What it is
- How to tell it apart
- How to recognise it
- How it forms
- Step by step
- Next step: what to do and document
- Common mistakes
- Elsewhere in DurgiPedia

- Study Test yourself

- Connections Connections

## What it is

A patterned injury is a bruise, abrasion or laceration whose shape reproduces the object that caused it: the two parallel lines of a rod, the sole of a shoe, the weave of fabric, a tyre tread, a grip of fingertips, the face of a hammer. The pattern is evidence: it narrows the type of object and may be compared with a specific one. Bruises and abrasions have their own pages; this page is about reading the pattern. The mark changes with time, swelling and the curve of the body, so it is documented early, with a scale, and compared by the forensic service. A pattern guides the investigation but rarely proves a single object, and some patterns can form in accidents.

## How to tell it apart

- The size of a bruise may be larger than the object because blood spreads; abrasions copy the shape more faithfully.
- The curve of the body distorts the pattern; compare with the object on a similar surface.
- Accidental falls against ribbed or edged surfaces can also produce linear patterns; in adults a tramline bruise is not specific.
- In a child, tramline bruises, loop marks and grip marks raise strong concern for abuse.

## How to recognise it

- Tramline bruise: two parallel bands of bruising with a pale centre.
- Imprint abrasion: the outline of an object pressed into the skin (sole, radiator grille, tyre).
- Grip marks: clusters of round bruises of fingertip size on opposite sides of a limb.
- Weave or clothing pattern: fabric texture printed on the skin by a heavy impact through clothing.

## How it forms

- A rod compresses the skin under it and pushes blood to the edges, where small vessels tear.
- An object pressed or dragged on the skin abrades the epidermis in its shape.
- Gripping squeezes the soft tissue between fingers and bone.
- Heavy impacts through clothing transfer its texture to the skin.

## Step by step

- Photograph the mark early, square to the skin, with a scale, and repeat over days as bruises develop.
- Measure the pattern: widths, spaces between lines, repeat units.
- Note clothing over the mark and keep it.
- Leave the comparison with a suspected object to the forensic service.

## Next step: what to do and document

- Photograph patterned marks with a scale before treatment and before they fade, and repeat if needed.
- Describe the pattern in neutral terms: «two parallel linear bruises 1 centimetre apart», not «stick marks».
- Ask how the injury happened and write the answer in the patient's words; note if the account fits the pattern.
- Keep clothing and any object brought in with chain of custody.
- In a child or a dependent adult with a patterned injury, follow the reporting route.

## Common mistakes

- Naming the weapon in the record instead of describing the pattern.
- Taking a single pattern as proof of one specific object.
- Photographing without a scale, or at an angle.
- Assuming a tramline bruise in an adult must come from a rod.

## Test yourself

Think of the answer, then tap the question to see it.

## What does a «tramline» bruise look like and what does it suggest?

Two parallel linear bruises with pale skin between them; it suggests a blow with a rod-like object.

## Which records a pattern more faithfully: a bruise or an abrasion?

An abrasion, because a bruise spreads beyond the outline of the object.

## Why is a tramline bruise not specific in an adult?

Because accidental falls onto edged surfaces or with fractured ribs can produce similar linear marks.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/forensic-medicine/patterned-injuries-what-the-mark-says-about-the-object/)

## Elsewhere in DurgiPedia

- [Mechanical and electrical injury: abrasion, contusion, laceration, wounds](https://durgical.com/en/general-pathology/mechanical-and-electrical-injury-abrasion-contusion-laceration-wounds/)
- [Mandatory reporting: public health, violence and abuse](https://durgical.com/en/medical-ethics/mandatory-reporting-public-health-violence-and-abuse/)

## Connections

## Related 7

- [Bruises and haematomas: recognising them, and why colour cannot date them](https://durgical.com/en/forensic-medicine/bruises-and-haematomas-recognising-them-and-why-colour-cannot-date-them/)
- [Abrasions](https://durgical.com/en/forensic-medicine/abrasions/)
- [Lacerations: blunt-force tears of the skin](https://durgical.com/en/forensic-medicine/lacerations-blunt-force-tears-of-the-skin/)
- [Skull fractures: linear, depressed, ring and basal](https://durgical.com/en/forensic-medicine/skull-fractures-linear-depressed-ring-and-basal/)
- [Abdominal and pelvic injuries](https://durgical.com/en/forensic-medicine/abdominal-and-pelvic-injuries/)
- [Child maltreatment: signs that should raise concern](https://durgical.com/en/forensic-medicine/child-maltreatment-signs-that-should-raise-concern/)
- [Road traffic injuries: pedestrians, drivers and riders](https://durgical.com/en/forensic-medicine/road-traffic-injuries-pedestrians-drivers-and-riders/)

## Related conditions 3

- [Child maltreatment (physical abuse, abusive head trauma, neglect)](https://durgical.com/en/conditions/child-maltreatment/)
- [Intimate partner and sexual violence (mental-health care)](https://durgical.com/en/conditions/intimate-partner-and-sexual-violence/)
- [Elder abuse and neglect](https://durgical.com/en/conditions/elder-abuse-and-neglect/)

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Educational content on forensic and legal medicine; not legal advice and no substitute for the technical guides of Colombia's National Institute of Legal Medicine and Forensic Sciences. Laws change: each page links the official text and says when it was last checked. For a real case, follow the guide in force and ask the competent authority.

Sources: [Blunt Force Trauma](https://www.ncbi.nlm.nih.gov/books/NBK470338/) (StatPearls Publishing (NCBI Bookshelf), 2023); [Patterned injuries from a modified sickle: Forensic observations and insights-Case report](https://pmc.ncbi.nlm.nih.gov/articles/PMC12332332/) (SAGE Open Medical Case Reports (PMC), 2025); [Accidental tramline bruising and rib fractures](https://pmc.ncbi.nlm.nih.gov/articles/PMC2850986/) (International Journal of Emergency Medicine (PMC), 2010); [Patterned abdominal wall bruise: An indicator of severe intra-abdominal injury](https://pmc.ncbi.nlm.nih.gov/articles/PMC8152392/) (Journal of Indian Association of Pediatric Surgeons (PMC), 2021).

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/forensic-medicine/patterned-injuries-what-the-mark-says-about-the-object/