Forensic Medicine · Supplementary · from Forensic Medicine

Case 3: Pattern Injury Analysis in Assault

Patient Presentation

Demographics: 28-year-old female elementary school teacher

Chief Complaint: "I was attacked by someone" — presented to the emergency department by ambulance with facial injuries and altered consciousness.

History of Present Illness: The patient was brought to the emergency department by paramedics after being found by a neighbor on the sidewalk outside her apartment building at approximately 23:30 on a Friday night. The neighbor heard screaming and found the patient lying on the ground, semiconscious and bleeding from facial injuries. The patient was initially confused but became more alert during transport. She reports that she was walking home from a nearby restaurant when she was grabbed from behind, struck multiple times in the face and head, thrown to the ground, and kicked. She describes the attacker as a male known to her — her ex-partner, from whom she had obtained a restraining order two weeks ago.

She reports being struck with what she believes was a closed fist to the left side of her face and an object (possibly a belt or strap) to her back and arms. She was kicked in the ribs and abdomen while on the ground. She briefly lost consciousness but is unsure for how long. She denies sexual assault. She reports one episode of vomiting after the attack.

Law enforcement officers accompanied the patient to the ED and have secured the scene. Forensic documentation is requested.

Past Medical History:

• History of prior domestic violence by the same perpetrator (two ED visits in the past 18 months with injuries attributed to "falls" at the time)
• Anxiety disorder
• No surgical history
• No allergies

Medications:

• Sertraline 100 mg daily
• No anticoagulants

Social History:

• Non-smoker, occasional social alcohol use
• Elementary school teacher
• Previously cohabited with the alleged perpetrator; separated 3 months ago
• Restraining order obtained 2 weeks ago
• No children
• Strong support network (friends, family)

Family History:

• Non-contributory

Physical Examination

• Vital Signs: BP 142/88 mmHg (likely pain/stress-related), HR 102 bpm, RR 20/min, Temp 36.9°C, SpO2 99% on room air, GCS 14 (E4 V4 M6 — confused verbal responses initially)
• General: Alert, tearful, anxious young woman in moderate distress; clothing torn at the right shoulder
• Head and Face:
• Left periorbital ecchymosis ("black eye") with edema, approximately 6 cm x 4 cm, dark purple
• 2.5 cm laceration of the left eyebrow with active bleeding, irregular (split) edges — consistent with blunt force impact against an underlying bony prominence
• Left zygomatic arch tenderness and swelling with crepitus on palpation
• Abrasion on the right forehead (3 cm x 2 cm), with embedded gravel — consistent with ground impact
• No palpable step-off of the orbital rims
• Tenderness over the left mandible; dental examination reveals a loose left upper lateral incisor
• Neck: No ligature marks, no petechiae above the level of compression, no tenderness of the cervical spine; thyroid cartilage intact
• Upper Extremities:
• Pattern injuries on the dorsal aspect of the left forearm (defense injuries): Three parallel linear contusions, each approximately 1.5 cm wide and 12-15 cm long, with a characteristic "tram-track" or "railroad track" pattern (two parallel lines of bruising with central clearing) — consistent with impact from a strap-like or belt-like weapon
• Fingernail avulsion of the left ring finger
• Abrasions on both palms — consistent with bracing against the ground during a fall
• Torso:
• Right lateral chest wall: two discrete shoe-print pattern contusions, approximately 10 cm x 8 cm each, showing a partial tread pattern with a wavy sole design — consistent with being kicked by a shod foot
• Tenderness on palpation of the right 8th and 9th ribs laterally with crepitus
• Left flank: 8 cm x 3 cm linear contusion consistent with belt/strap impact
• Abdomen: Mild diffuse tenderness, more prominent in the left upper quadrant; no guarding or rebound tenderness; no distension
• Lower Extremities: Bilateral knee abrasions consistent with falling to the ground
• Neurological: GCS improved to 15 during examination; cranial nerves intact; no focal deficits; pupils equal and reactive

Workup and Results

Laboratory Studies:

Imaging/Additional Studies:

• CT head without contrast: No intracranial hemorrhage, no skull fracture, no midline shift; mild soft tissue swelling over the left temporal region
• CT facial bones: Non-displaced fracture of the left zygomatic arch; no orbital floor fracture; no Le Fort fracture pattern; intact mandible
• Chest X-ray: Fractures of the right 8th and 9th ribs laterally; no pneumothorax; no hemothorax; no pulmonary contusion
• CT abdomen/pelvis with IV contrast: Small perisplenic fluid collection without active extravasation; no solid organ laceration; no free air; grade I splenic contusion suspected
• Forensic photography: Detailed photographic documentation of all injuries with color scale, ruler for measurements, and multiple angles; performed by trained forensic nurse examiner
• Evidence collection: Fingernail scrapings collected from both hands; torn clothing bagged; trace evidence (fibers) collected from pattern injuries

Clinical Image

Educational diagram illustrating common pattern injuries encountered in assault cases, including tram-track bruising from strap-like weapons, shoe-print contusions from kicks, and defense injuries on the forearms. Source: Educational illustration.

Diagnosis

Multiple Pattern Injuries Consistent with Assault: Blunt Force Trauma by Fist, Shod Foot, and Strap-Like Weapon

• Left zygomatic arch fracture (non-displaced)
• Right 8th and 9th rib fractures
• Grade I splenic contusion
• Mild concussion (GCS 14, improving)
• Multiple contusions, lacerations, and abrasions in a distribution consistent with the reported mechanism

Key Diagnostic Criteria:

• Tram-track (railroad track) contusions on forearms: Two parallel lines of bruising with central clearing, pathognomonic for impact with a strap-like or rod-like object; location on the dorsal forearm is classic for "defense injuries" (arms raised to protect the head)
• Shoe-print pattern contusions on the chest: Patterned bruising replicating a shoe sole tread pattern, confirming a kick with a shod foot and potentially identifiable to a specific shoe
• Split laceration of the eyebrow: Irregular wound edges with bridging tissue strands in the wound depth, distinguishing it from an incised wound; located over a bony prominence, consistent with blunt force impact
• Defense injuries: Forearm contusions + palm abrasions + fingernail avulsion collectively indicate the victim attempted to defend herself
• Injury distribution pattern: Injuries to the face, arms (defensive), and torso (kicks while grounded) are consistent with the described sequence of assault events

Treatment Plan

1. Medical management:

• Laceration repair of the left eyebrow (5 interrupted sutures with 6-0 nylon after irrigation and exploration to rule out foreign body)
• Pain management: acetaminophen/oxycodone with rib binder for rib fractures
• Neurological observation for concussion: neuro checks every 2 hours for 24 hours
• Serial abdominal examinations and repeat hemoglobin in 6 hours for splenic contusion monitoring
• Tetanus prophylaxis (Tdap booster)
• Dental consultation for the loose incisor
• Ophthalmology consultation to rule out occult globe injury given periorbital trauma
• Oral and maxillofacial surgery consultation for zygomatic arch fracture management

1. Forensic documentation (critical):

• Comprehensive photographic documentation of all injuries with measurement scales, completed by forensic nurse examiner (SANE/SAFE trained)
• Body diagram mapping of all injuries with detailed written descriptions including size, shape, color, pattern, and anatomical location
• Collection and preservation of trace evidence: fingernail scrapings, clothing, trace fibers
• Documentation of the patient's own account of the assault in her own words
• Documentation of injury age estimation based on color and characteristics

1. Safety planning and resources:

• Social work consultation for safety assessment and discharge planning
• Domestic violence advocacy service referral
• Emergency shelter arranged if needed for safe discharge
• Review and reinforce restraining order; law enforcement coordination
• Provide the National Domestic Violence Hotline number (1-800-799-7233)

1. Legal coordination:

• Provide medical records and forensic documentation to law enforcement upon appropriate legal request
• Forensic examiner available as expert witness if prosecution proceeds
• Chain of custody maintained for all evidence collected

Key Learning Points

• Pattern injuries reproduce the shape, pattern, or characteristics of the weapon or object that caused them and are critically important in forensic medicine for linking injuries to specific weapons or mechanisms. Common examples include tram-track bruising (rods/belts), bite marks, ligature marks, and shoe-print contusions.
• Defense injuries (bruises and abrasions on the dorsal forearms, hands, and fingers) indicate that the victim was conscious and actively attempting to protect themselves during the assault; their presence or absence is a key forensic finding.
• Split lacerations caused by blunt force over bony prominences can be distinguished from incised (sharp force) wounds by their irregular edges, bridging tissue strands within the wound, and intact hair follicles crossing the wound — this distinction has significant medicolegal implications.
• Forensic documentation in assault cases must include scaled photography, precise measurements, anatomical location, and wound characteristic descriptions; this documentation may be the only permanent record if injuries heal before trial, which can occur months or years later.
• Healthcare providers are mandated reporters of suspected domestic violence in many jurisdictions; all emergency departments should have protocols for forensic evidence collection, photographic documentation, safety planning, and domestic violence advocacy referral.

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