Plaster of Paris has been used for centuries to immobilize fractures. It was first used by Arab physicians in the 9th century and became more widely used in the 19th century. While plaster of Paris remains effective, it can cause complications like skin injuries if not applied properly. Synthetic casting materials have advantages over plaster of Paris like being lighter and more radiotransparent, but plaster of Paris remains a common choice due to its lower cost. Both the application technique and materials used can affect the temperature under the cast and risk of burns.

1. Plaster of Paris
(POP)
Muhammad Abdelghani

2. Historical Perspective
• 9th century AD:
– Arab physicians used
strips of linen soaked in
a mixture of lime and
egg white which would
set “hard as stone” for
treatment of fractures.

3. Historical Perspective
• 1852: Classical plaster bandage.
– Antonius Mathysen, a Dutch army surgeon,
treated battle wounds in the Crimean War with
cotton bandages filled with dry plaster of Paris
(POP).
– POP was so called because it was first
prepared from the gypsum mined in Paris,
France.

4. Historical Perspective
• 1927: Binder ingredients (starches, gums,
and resins) were added to improve the
adherence of the plaster to the gauze.
• Later, other additives were incorporated to
change the physical properties pf POP,
such as setting time, which allowed
standardized production.
• 1970s: Synthetic materials.

5. Current Indications
• Immobilisation of
fractures
• Correction of deformities
• Splinting limbs
• Immobilisation of the
spine.

6. Complications
• Deformity
• Skin injuries
• Rashes
• Compartment syndrome
• Burns

7. What Causes Complications?
Technical Error Resulting Complication
Improper and irregular application
of padding
Pressure sores beneath the cast
Inadequate padding material at the
ends of the cast
Sharp edges and skin irritation
Aggressive cast molding Pressure sores beneath the cast
Inadequate casting material Cast breakdown and loss of control
of the unstable fracture
Tight application of casting material or failure
to allow for underlying injury swelling
Compartment syndrome
Hot dip water Elevated setting temperatures / Skin
burns

8. Exothermic Reaction
• Occurs as the cast hardens.
• Causes the temperature within and
beneath the cast material to rise.
• Temperature may rise to dangerous
levels: Risk of thermal injury.

10. Exothermic Reaction
• Recommendations for safe casting:
– Use luke-warm water with plaster casts
– Use cool water with fiberglass casts
– Pad appropriately to avoid sharp edges or
cast pressure points

11. Exothermic Reaction
• Lavallette et al:
– Risk of burns is directly related to:
• dip water temperature
• length of time the plaster is kept in the dip water
– Dip water temperature can play a key role in
the ultimate temperature beneath the cast.

12. Exothermic Reaction
• Kaplan:
– Temperature elevations can be related to the
plaster being dipped too briefly and the water
being squeezed too aggressively out of the
plaster.
– The water itself helps to release the heat, and
if there is not enough, the plaster gets hotter.

13. Exothermic Reaction
• Selesnick & Griffiths
– With fiberglass cast materials, use only cool
dip water to reduce the chance of burns.

14. Exothermic Reaction
• Hutchinson and Hutchinson (2008):
– There is a direct relationship with increasing
dip water temperature from 32 to 39º C and
the ultimate peak temperature beneath both
plaster and fiberglass casts.

15. Exothermic Reaction
• Dirty dip water and ambient humidity have
also been implicated as contributing to
temperatures beneath maturing casts.
• Lavalette and Ganaway:
– Plaster residue in the dip water might play a
role in elevating cast temperature and
broadening the time-temperature curve; i.e.,
maintaining the peak temperature for a longer
period.

16. Exothermic Reaction
• Ganaway:
– Cast padding plays little role in effecting the
temperature beneath a cast.
• Hutchinson & Hutchinson:
– Increased cast padding:
• little effect on the fiberglass casts.
• significant effect of elevated temperatures with additional
layers of Webril applied beneath 20 layers of extra-fast setting
plaster.
– Explanation: increased insulation traps the heat beneath.
• Cast padding likely plays a greater role to protect the
skin against pressure points than its effect on
temperature.

17. Exothermic Reaction
Conclusion:
• Extra fast setting plaster achieves peak temperatures quicker and
higher than slower setting plasters.
• Increased thickness of casting materials (both plaster and
fiberglass) are related to increased temperatures beneath the cast.
• Dip water temperature is directly related to the peak temperature
beneath the cast.
• Prefabricated splints do not achieve the same temperature levels
when compared to circumferential casts and, therefore, from a
thermal perspective, may be safer.
• Thickness and type of cast padding did not play a significant role
regarding ultimate temperatures beneath the cast in this study.
• At the thicker levels of padding, it may actually serve as an insulator
entrapping additional heat.
• The greatest risk of thermal injury occurs when a thick cast using
warm dip water is allowed to mature while resting on a pillow.

18. Cast Wedging
• When fracture reduction is
incompletely obtained in a cast,
wedging may be a viable
technique to correct deformity
and avoid surgical intervention.

19. Cast Wedging
• Types of wedging:
–Open wedging
–Closed wedging
–Combination of opening and closed
wedging.

20. Cast Wedging
• Open wedging:
– More commonly used
– Avoids the risks that accompany closing
wedges

21. Cast Wedging
• Closed wedging:
– Possible complications:
• Pinching of the skin (may cause skin breakdown)
• Accumulation of cast padding at the wedge site
(may also cause skin breakdown)
• Fracture shortening
• Reduction of the volume of the cast (may result in
compartment syndrome).

22. Cast Wedging
• Predicting the wedge size:
– Bebbington, Lewis, and Savage:
• Trace the angle of displacement onto the cast itself using a
marking pen.
• The line is meant to represent the fracture fragments.
• Wedges are then inserted until the bent line becomes
straight.
– Guastavino and Husted:
• Both introduced formulae that could be used to predict the
amount of wedging.
• Husted’s method even accounted for radiographic
magnification.

23. Synthetic Cast Materials
• Introduced on the market place in the
seventies, but have not superseded
traditional POP.

24. Synthetic Cast Materials
• Advantages:
– Better physical and mechanical properties
than traditional POP
– Lighter
– More resistant to humidity
– More radiotransparent
– Generate less dust when removed

25. Synthetic Cast Materials
• Disadvantages:
– Less malleable
– Cause higher pressure in case of limb edema

26. Synthetic Cast Materials
• POP therefore remains indicated in the
acute posttraumatic or postoperative
period.
• This material is also cheaper, but the
pecuniary benefit is limited for several
reasons, particularly because POP is
associated with a higher rate of cast
replacement.

27. Synthetic Cast Materials
• Thermoplastic Materials:
– More recent
– Used to make splints and orthoses,
particularly at the wrist and hand.

28. References
• Colditz JC: Plaster of Paris: The Forgotten Hand
Splinting Material. J Hand Ther 2002; 15:144-157
• Hutchinson MJ, Hutchinson MR: Factors contributing
to the temperature beneath plaster or fiberglass cast
material. Journal of Orthopaedic Surgery and Research
2008, 3:10
• Schuind F, Moulart F, Liegeois JM, Dejaie Strens LC,
Burny F: La contention orthopédique. Acta Orthopædica
Belgica 2002; 68(5):439-461
• Wells L, Avery AL, Hosalkar HH, Friedman JE,
Davidson RS: Cast Wedging: A “Forgotten” Yet
Predictable Method for Correcting Fracture Deformity.
UPOJ 2010; 20:113-116