Mechanical Injuries- Abrasion, Contusion & Bruise | Dr. Shilpa Singh - MD Forensic | Aakash PG Plus

Summary

This video script explores common types of mechanical injuries like abrasions and contusions, highlighting their medical and legal implications. It details different abrasion types (scratch, graze, crush, imprint), the process of healing, and the importance of these injuries in forensic analysis. Contusions, or bruises, are discussed in terms of their formation, healing stages, and the significance of their color changes over time. The script also covers the role of these injuries in road traffic accidents, patterned contusions, and artificial bruises. Ultimately, it emphasizes the importance of understanding these injuries for accurate forensic investigation and legal proceedings.

Takeaways

• 😀 Abrasion is a superficial injury that affects only the skin or mucous membrane, with no depth. It is a two-dimensional injury, characterized by length and breadth.
• 😀 There are different types of abrasions, including scratch or linear abrasions, grace abrasions (often seen in road traffic accidents), and imprint abrasions (such as bite marks or tire tracks).
• 😀 The mechanism of abrasion is influenced by the force applied—tangential forces cause linear or grace abrasions, while compression forces can create imprint abrasions.
• 😀 Timing of abrasions is crucial for medical-legal purposes. Fresh abrasions are red, while scabs change color over time, indicating the duration since the injury occurred.
• 😀 Abrasions heal relatively quickly, usually within a week, and typically don't result in permanent scars, though the timing and scab color can help determine the age of the injury.
• 😀 Medical-legal importance of abrasions includes identifying the direction of injury based on tissue heaping, identifying the causative weapon, and determining the time and place of the injury.
• 😀 Post-mortem abrasions differ from ante-mortem abrasions. Post-mortem abrasions usually occur on bony prominences and lack the signs of healing or vital reactions.
• 😀 A contusion (bruise) is caused by the rupture of capillaries under the skin without breaching the skin's surface. It appears as a discolored area with extravasation of blood into the tissues.
• 😀 Bruise appearance can vary based on factors such as the site of injury, age, skin color, and vascularity. Contusions show a typical color progression from red to blue, green, and yellow as they heal.
• 😀 Patterned bruises, such as those caused by spherical objects or rods, can provide clues to the weapon used and the nature of the injury. Delayed bruising may also occur due to internal bleeding.
• 😀 Migratory bruises, or bruises appearing at a site distant from the impact, occur due to the seepage of blood along facial planes. An example is bruising around the eyes (black eye) after a cranial injury.
• 😀 Post-mortem lividity can sometimes be mistaken for bruising, and artificial bruises caused by toxic substances like marking nuts or calotropis can mimic true bruising, complicating diagnosis.

Q & A

What is an abrasion, and how is it different from other injuries?

An abrasion is a superficial injury to the skin or mucous membrane, characterized by the loss of the outer layers of the skin. It is a two-dimensional injury, meaning it only has length and breadth, not depth. This differs from other injuries like contusions or lacerations, which involve deeper tissue damage.

What are the different types of abrasion discussed in the video?

The different types of abrasion discussed include scratch (linear abrasion), grace abrasion (caused by dragging over a rough surface), crushing or pressure abrasion (due to sustained pressure), and imprint abrasion (caused by rough objects like a radiator grille or bite marks).

What is the significance of tissue heaping in an abrasion?

Tissue heaping at one end of an abrasion indicates the direction of the force applied. This can help in determining the direction from which the injury occurred, which is crucial in medico-legal investigations, especially in road traffic accidents.

What is the typical healing time for an abrasion?

An abrasion typically heals quickly, often within 7 to 10 days, with minimal bleeding and no permanent scarring. Scab formation might indicate the age of the injury, with a reddish scab appearing within 12 to 24 hours, and a dark brown scab appearing after 4 to 5 days.

How can the timing of an abrasion be determined?

The timing of an abrasion can be determined by observing the color of the scab. Fresh abrasions are bright red, while a reddish-brown scab indicates 2 to 3 days since the injury. A dark brown scab corresponds to 4 to 5 days, and after 7 to 10 days, the scab falls off, revealing a denuded or depigmented area.

What are the key medical-legal aspects of abrasions?

Key medical-legal aspects include determining the direction of the injury, identifying the weapon or cause (such as bite marks or radiator grilles), and using the timing of scab formation to estimate when the injury occurred. In road traffic accidents, dirt or glass particles on the abrasion can help identify the location of the injury.

What are post-mortem artifacts, and how can they affect the diagnosis of abrasions?

Post-mortem artifacts occur after death, caused by handling or positioning of the body. These can mimic abrasions and lead to misdiagnosis. For instance, abrasions caused by insects or animals can appear similar to real abrasions but do not have the same healing characteristics.

What is the difference between an abrasion and a contusion?

An abrasion involves the scraping off of skin or mucous membrane, whereas a contusion (bruise) involves the rupture of capillaries beneath the skin, leading to blood leakage without breaking the skin's surface. Abrasions are surface-level injuries, while contusions occur deeper in the tissue.

How does the color progression of a contusion help determine its age?

The color progression of a contusion follows a specific pattern. Initially, it appears red due to fresh blood. Within a day or two, it turns blue due to deoxygenated hemoglobin, followed by green as the hemoglobin breaks down. Later, it turns yellow as bilirubin forms, indicating the bruise is healing.

What is a migratory bruise, and how does it occur?

A migratory bruise occurs when blood seeps from the original injury site to another area due to the arrangement of the fascial planes. For example, a skull fracture might cause bruising around the eyes (black eye), while a pelvic injury might lead to bruising in the thighs or ankles.