Preparation and quality control of plaster
Factory-made or homemade plaster bandages (gauze with rubbed-in calcium sulfate powder) are used for casts. High-quality plaster should be free of grains, lumps, and hydrogen sulfide (rotten egg) odor when mixed with water. When squeezed in the hand, the dry powder should crumble easily.
The setting test is performed by mixing plaster and water in equal proportions: the formed plate must harden within 6–7 minutes and not crumble when fractured. Plaster damaged by moisture can be restored by calcination at 120 °C, and lumpy plaster can be sieved.
Soaking bandages:
- Water temperature should be around 20 °C.
- Bandages are immersed carefully, without crushing, 1–2 at a time.
- Soaking time is 1.5–2 minutes (until air bubbles cease).
- The bandage is retrieved by holding its ends and gently squeezed.
General application rules
Applying a plaster cast requires adherence to a number of strict rules to ensure efficacy and safety:
- The limb is given a functionally advantageous position.
- In fractures, fragment reduction is performed and maintained until the plaster sets completely.
- Fixation of two adjacent joints is mandatory.
- Bony prominences are protected with pads of non-hygroscopic (plain) cotton wool.
- Fingertips are left exposed to monitor blood circulation.
- The cast is meticulously molded, avoiding tissue compression.
- The assistant must hold the slab with the entire palm, not fingers, to prevent indentations and pressure sores.
The date of injury, date of application, and expected removal time must be marked on the wet cast with an indelible pencil.
Types of plaster casts
Depending on shape and purpose, several types of casts are distinguished:
- Slab, circular, and slab-circular casts.
- Unlined casts — considered the most effective (usually slab-circular type). Cotton wool is used only over bony prominences.
- Fenestrated casts — have a cut-out "window" for wound monitoring, dressings, or pus drainage.
- Bridged casts — two separate parts of the cast are connected by plaster or metal bridges. Used over extensive wounds or joints.
There are also special casts for specific localizations, for example, a thoracobrachial cast (for humeral fractures) or a dorsal plaster slab (for radius fractures).
Drying, monitoring, and removal
The patient can only be repositioned 25–30 minutes after application, once the plaster has set, otherwise deformation or displacement of fragments may occur. Complete drying takes 1–3 days on a bed with a rigid wooden board. The process can be accelerated using Sollux lamps or hair dryers.
Purulent complications may develop under the cast. They are indicated by localized throbbing pain, fever, enlargement of regional lymph nodes, and leukocytosis. In such cases, examination and adjustment of the cast are required.
The cast is removed after fracture consolidation using special shears or a saw by cutting it lengthwise. The limb must be extracted extremely carefully to avoid damaging the fragile callus.
Class and exam questions
Plain non-hygroscopic cotton wool is more elastic and does not absorb sweat, which reduces the risk of skin maceration under the cast.
Plain non-hygroscopic cotton wool is more elastic and does not absorb sweat, which reduces the risk of skin maceration under the cast.
The slab must be supported with the entire surface of the palm. If held with the fingertips, indentations will remain in the unset plaster, which can cause pressure sores.
The slab must be supported with the entire surface of the palm. If held with the fingertips, indentations will remain in the unset plaster, which can cause pressure sores.
Symptoms include the onset of localized throbbing pain, elevated body temperature, enlarged lymph nodes, and an increased white blood cell count.
Symptoms include the onset of localized throbbing pain, elevated body temperature, enlarged lymph nodes, and an increased white blood cell count.
What else to study on this topic
- Features of reduction in compression fractures of the spine (wedge-shaped, comminuted, fracture-dislocations).
- Spine reclination method.
- Technique of applying a slab-circular cast to the lower leg.
- Features of applying a plaster bed for the femur and hip joint.
Master the entire topic in the "General Surgery" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on the topic "Plaster Casts" and 3,335 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 70 video lessons on the subject
Other topics in "CHAPTER 10. GENERAL ISSUES IN TRAUMATOLOGY"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.