Principles of POP Casting

A complete guise to how to apply POP on limbs to treat different musculoskeletal issues.

1. PRINCIPLES OF USE OF POP Dr. Sohail Razzaq FCPS (ORTH) Associate Professor of Orthopedic Surgery Jinnah Hospital / Allama Iqbal Medical College Lahore.

2. In troduction Definition Statement of importance Historical background Physiochemical characteristics of POP Ideal cast Classification Indications Advantages/disadvantages Patient assessment Rules guiding POP use Technique Materials Application Removal Aftercare Cast care instructions Complications Alternative casting materials Conclusion

3. INTRODUCTION POP – Plaster of Paris First applied in the treatment of fractures over 150 years ago P roven indispensable in the non-operative management of not only musculoskeletal injuries but other ailments requiring immobilization as well. Its use however isn’t without risk S ound knowledge and properly-honed skills in its application and care are necessary to maximize outcome.

4. Casting properties of POP were first observed when a house built on gypsum burnt down in Paris. It was found after rain fall, that the footprints in the mud were caked upon drying. First used in fracture care by Antonius Mathijsen , A Dutch army surgeon in 1852.

5. PHYSIOCHEMICAL PROPERTIES OF POP POP is CaSO4 .½H2O in its anhydrous form impregnated in gauze which has been pre-strengthened with starch or dextrose. Obtained from heating gypsum to 120°C. The hydration of CaSO4. ½H2O converts it from powder form to crystalline form which gives rise to cast. This is the process of setting and is an EXOTHERMIC REACTION, CaSO4 .½H2O + 3 /2H2O → CaSO4 .2H2O + Heat

6. POP incorporates 20% of the water it soaks up, the remaining 80% is lost during drying. Setting time – time taken to convert from powder form to crystalline form • Average time is 3 – 10 mins • Reduced by high temp, salt solution, borax solution, addition of resin • Increased by low temp, sugar solution

7. Setting time is three times longer at 5 °C than at 50°C Movement of the plaster while it is setting will cause gross weakening. Drying time – time taken for POP to convert from crystalline form to anhydrous form • Influenced by ambient temperature and humidity • Arm cast: 24 – 36hrs • Leg cast: 48 – 60hrs • Hip spica : up to 7 days The optimum strength is achieved when it is completely dry

8. AN IDEAL CAST Suitable for direct application Easy to mould Non toxic Unaffected by water Transparent to x-rays Quick setting Able to transmit air Strong but light weight Non-inflammable Non-messy Long shelf life Cheap

9. CLASSIFICATION Based on pattern of application: Slab : POP encloses partial circumference Cast : POP encloses full circumference Spica : B andage that is applied in successive V-shaped crossings, includes trunk and one or more limbs (Hip spica ) Brace : Splintage which can allow motion at adjacent joints

10. CLASSIFICATION Based on interposition of material: Unpadded No material interposed between POP & skin Practiced by Bohler Charnley recommended its use in Rx of Colles , scaphoid and Bennet fractures A practice in antiquity Bologna cast Generous amount of cotton padding is applied to the limb before putting cast Most commonly employed method 3-tier cast Interposed materials are stockinette & wool or cotton padding Best method but expensive

11. Indications Fractures Ligament injuries Reduced dislocations Musculoskeletal infections Deformity correction Severe soft tissue injuries esp. across joints Post tendon repair Post-operatively to augment internal fixation Inflammatory conditions – arthritis, tenosynovitis

12. Advantages Slower setting Infinitely moldable when wet Cheap Easy to remove Durable Heavy Messy Significantly weakened if cast is wet Partially radio-opaque Disadvantages

13. PATIENT ASSESSMENT The surgeon should examine the limb and fracture site, documenting any skin lesions and neurovascular status Radiographs should also be reviewed thoroughly to determine fracture pattern The motions required to adequately reduce the fracture should be rehearsed ahead of commencement of procedure

14. RULES GUIDING POP USE POP should be applied by the surgeon Procedure requires an assistant A guide to appropriate size: • Arm & forearm – 6” • Wrist – 4” • Thumb & fingers – 3” • Thigh & leg – 8” • Ankle & foot – 6”

15. RULES GUIDING POP USE Apply POP one joint above and below Joint should be immobilized in functional position Padding should be adequate esp. over bony prominences e.g. olecranon, ulnar styloid, patella, fibular head, malleoli, heel. POP shouldn’t be too tight or too loose The plaster should be of uniform thickness throughout Check neurovascular status after cast application Do check x-ray for acceptability of reduction

16. TECHNIQUE Materials • POP bandage • Crepe bandage (for slabs) • Casting gloves • Basin of water • Bandage scissors • Padding ( Soffban ®) • Sheets • Stockinette • Adhesive tape

17. TECHNIQUE Prepare injured site • Fracture is reduced and assistant holds limb in position of function, in a manner that is unobtrusive to the application of cast • Stockinette is measured, extending 10cm beyond determined limits of cast, and threaded over limb.

18. TECHNIQUE Wool padding is applied gently and snugly, starting from distal to proximal with 50% overlap between successive turns, extending 2-3cm beyond edges of splint Padding is applied generally in 2 layers, but may be increased where there are bony prominences or if significant swelling is anticipated Padding sizes: hand : 2”, rest of upper limb: 3-4 ” foot : 3”, rest of lower limb: 4-6”

19. POP APPLICATION POP to be used is dipped completely with both hands into tepid or slightly warm water and held there till bubbling stops Prior to this, for slabs, the required length is measured and layered. It is then brought out and lightly squeezed to get rid of excess water If a slab is to be created, the wet plaster is kept on flat surface and the hand is run from one end to another to get rid of air bubbles which may cause slab to be brittle and the layers to separate when dry. 6-10 layers for upper limb and 12-16 layers for lower limb would suffice

20. For slabs POP slab is applied and moulded onto the limb contours Moulding is only with palms Stockinette & padding are rolled over the edge of slab and crepe bandage is applied from distal to proximal Slabs may be used alone or to reinforce casts For cast POP is applied in distal to proximal with 50% overlap POP is applied snugly, compressing padding thickness by 50% The padding is rolled over and the final turns of POP are rolled over it

21. Above Elbow An above elbow plaster cast or slab is applied from knuckles of hand (distal palmar crease anteriorly] and covers lower two thirds of arm Below Elbow While distal extent is same as above, proximally the plaster ends below elbow crease. Above Knee Distal extent is up to metatarsophalangeal joints and proximally it covers lower two thirds of thigh . Below Knee Distal extent is same, proximal extent ends below knee.

22. POP PRECAUTIONS Where swelling is anticipated use a slab instead of cast, if a cast must be used then it should be well-padded POP applied postoperatively may have to be split as swelling may be significant ( e.g post-tourniquet release, inflammatory edema )

23. POP REMOVAL Slabs are removed by cutting the bandage, carefully avoiding nicking the skin For casts – Using shears » Heel of the shears must lie between plaster and skin, avoiding bony prominences » Avoid cutting over concavities » The route of the shears should lie over compressible soft tissue » The lower handle should be parallel to the plaster – Using electric saw » Do not use unless there’s wool padding » Do not use over bony prominences » The cutting mov’t should be up and down not lateral » Do not use blade if bent, broken or blunt

24. Cast cutting shears Electric saw

25. AFTERCARE Following POP application, check neurovascular status and check reduction by x-rays. Counsel the patient on signs of neurovascular compromise – excessive pain, excessive swelling, bluish or whitish discoloration of digits Reinforce all cracks and weak areas with more POP locally Limb elevation reduces swelling, pain and risk of too tight cast Check if the POP is restricting movement Ensure that all joints not immobilized by cast have full range of motion Any area of localized pain should be windowed as it may be a developing pressure sore The patient should be reviewed in 1 – 2 weeks and x-rays done to reaffirm maintenance of reduction

26. CAST CARE INSTRUCTIONS Keep the cast clean & dry Routinely check the cast for cracks or breaks Do not scratch the skin under the cast by inserting objects inside the cast Do not put powder or lotion inside the cast Encourage the patient to move his fingers or toes to promote circulation In case of itching, apply ice packs or place hair dryer (cool air) against one end to draw air in through it Any area of localized pain should be windowed as it may be a developing pressure sore

27. WHEN TO COME BACK TO HOSPITAL Cast is too tight Develops fever Increased pain Increased swelling above or below the cast Complaints of numbness or tingling Drainage or foul odour from the cast Cold fingers/toes Cant move fingers/toes

28. COMPLICATIONS Due to tight cast • Pain • Pressure sores • Edema distal to plaster • Circulatory compromise • Compartment syndrome • Peripheral nerve injury • Loss of functional limb (Gangrene, VIC) • Disuse orteoporosis Due to improper application • Plaster blisters • Joint stiffness and malposition of limb • Loose cast Due to allergy • Allergic dermatitis • Purulent dermatitis Others • Muscle wasting • Skin abrasion/laceration

29. ALTERNATIVES TO POP POP with melamine resin Fiber glass

30. FIBER GLASS CAST A plaster made from reinforced polymer of a plastic matrix reinforced by fine fiber of glass. Also called Glass-reinforced plastic (GRP) or Glass fiber reinforced plastic (GFRP) Fiberglass bandages are usually impregnated with polyurethane Mostly used in those cases where healing process has already begun

31. FIBER GLASS CAST Advantages Disadvantages Lighter Costly Faster setting Less pliable, more difficult to mould 3x stronger than POP Higher risk of pressure and constriction of limb Impervious to water More prone to give rise to allergic reactions Radiolucent Not used in acute conditions

32. CONTRAINDICATIONS Open fractures Impending compartment syndrome Neurovascular compromise Reflex sympathetic dystrophy Skin infection or ulcers Swelling of the limb Allergy to cast material Comminuted fractures

33. PLASTER DISEASE When a limb is put into plaster and the j oints are immobilized for a long period of time, joint stiffness, muscle wasting and osteoporosis are unavoidable. This syndrome can be reduced to a minimum by the early use of functional braces, isometric exercises and early weight bearing, which in turn promote early retrieval of function.

34. CONCLUSION Despite revolutionary advances in management of injury, especially those of the musculosketelal system, POP still remains very useful in carefully selected cases, obviating the need for unnecessary surgery with its attendant risks

35. THANK YOU…