Upendra Kumar
- Casting Materials and Orthopedic Casts
- Dressing Materials
- Orthopedic Strappings, Bandages, and Slings
- Orthopedic Tractions and their Equipment
- Patients on External Fixators
- Miscellaneous Equipment
Although casting persisted as an integral part of conservative treatment in orthopedics from 18th century hence, the basic knowledge of materials used in casting is of utmost importance. Side by side principle of reduction and their maintenance are also important.
PLASTER OF PARIS BANDAGE (FIG. 1)
- First used by Mathijsen, a Dutch military surgeon, in the year 1852.
- Characteristics:
- Plaster of Paris (POP) impregnated bandage
- Setting time: 4–5 minutes
- Full strength of cast is achieved in 24–48 hours
- Chemical reaction—POP (calcium sulfate hemihydrate) is obtained by heating gypsum (calcium sulfate dihydrate). And again when POP comes in contact of water, gypsum reappears with release of some heat (exothermic).2(CaSO4.2H2O) + heat → 2(CaSO4.1/2 H2O) + 3H2O2(CaSO4.1/2H2O) + 3H2O → 2(CaSO4.2H2O) + heat
- Water-resistant cast is prepared when melamine resin is mixed with POP.
- Commonly available sizes—4 inch, 6 inch × 2.7 meters.
- Factors affecting setting time:
- Temperature of water
- Manufacturer's setting time
- Impurities in plaster
- Water condition (hard and soft)
- Humidity
- Room temperature.
- Cast index and gap index:
- Cast index: It is defined as inner ratio of a plaster cast in anteroposterior (AP) view and lateral view of limb kept in cast.
- Gap index: It measures the thickness of padding, i.e., gap between inner layer of cast and skin.
- Uses of POP bandage:
- As a slab for immobilization:
- Extent of slab coverage—50–70% circumference (two-thirds) of limb
- For upper limb—6–8 layers and for lower limb—10–12 layers
- Volar surface in upper limb and dorsal surface in lower limb are preferred. Why? Molding is easier against splint and also helps in reduction maintenance.
- As definitive casting:
- Wrapped around whole circumference of limb or part is involved
- The overlapping of bandage is one-third to one-half of previous turn
- Thickness of cast varies according to nature of fracture, limb type (upper or lower), and age of patient
- Functional cast bracing
- Deformity correction serial casting
- Partial weight relieving orthosis
- Spica
- Charley's traction unit
- Pin plaster technique.
- Complications with POP bandage:
- Neurovascular compromise
- Compartment syndrome
- Pressure sore
- Purulent dermatitis
- Reactionary edema
- Fracture disease
- Wasting of limb
- Joint stiffness
- Loss of reduction.
- Care of a limb in plaster:
- Constant movements of finger or toes
- Keep limb elevated
- Do not bring the plaster in contact with water
- Report immediately if any swelling, color changes, numbness, or excess pain.
FIBERGLASS PLASTER (FIG. 2)
- Characteristics:
- Composition: Fiberglass impregnated with polyurethane polymer
- Colorful and sticky
- Setting time: 1–2 minutes
- Full strength of cast is achieved in 2–4 hours
- Activated by water or other agents.
- Caution: Surgical gloves must be worn before using this cast.
- Commonly available sizes 3” and 5” × 3.6 meters.
- Advantages: Lightweight, waterproof, and lesser setting time.
- Disadvantage: Costlier.
STOCKINETTE (FIG. 3)
- Characteristics:
- Extend it about 10 cm beyond each end of intended splint site.
- Commonly available in size 3” (upper limb) and 5” (lower limb) × 20 meters.
- Uses: Before application of slab and cast over limbs.
- Advantages: Prevention from skin complications like allergy, dermatitis, etc.
COTTON ROLL (FIG. 4)
- Properties:
- 100% cotton and bleached to white
- High absorbent property
- Single and uniform lap without joints as thin long continuous layer.
- Available in standard 500 g but 100 g, 200 g, 300 g, and 400 g are also found.
- Various uses like:
- For cleaning and swabbing of wounds
- For padding before applying slab and cast
- For wrapping around splints, etc.
COTTON ROLLER BANDAGE (FIG. 5)
- Properties:
- 100% cotton fabrics with a loose open weave and bleached to white
- Quick absorbent property
- Number of holes per square centimeter of cotton gauze—4 × 4 = 16.
- Cotton roller bandages are commonly available in 4” and 6” × 4 meters.
- Used for:
- For POP slab application
- For wrapping around various splints
- During wound dressing
- The most common fastening article in ward.
- Starch impregnated roller bandages become slimy when soaked in water and it becomes harder when dried. This property is utilized to provide extra strength to POP slabs.
- Why wet roller bandaging is used during POP slab application?
- Dry bandages absorb water from POP and decrease the setting time and side-by-side it does not incorporate well with slab.
PRINCIPLE OF REDUCTION AND CASTING
- For fracture reduction, appropriate amount of traction and countertraction is applied in proper direction.
- Reduction is achieved by manipulation of distal fragment.
- A perfect reduction is said when all cortices are in contact at fracture site or reduction is said to be acceptable when both fragments have at least 50% contact both in AP and lateral views.
- Even minimal rotation at fracture site is hardly accepted.
- Appropriate padding should be done around fractured limb, especially over bony prominence.
- Reduced position of limb should maintain before, during, and after casting.
- Any indentation during molding and wrinkles should be avoided during cast application.
- A reduced fracture is maintained in such a way that one joint above and one joint below is fully immobilized. But exceptions are Colles’ fracture, fracture around ankle, etc.
- The position of limb should be maintained in functional position or position of immobilization. For most of the joint, these two are the same but for wrist and hand, these stand differently.
- Functional position: The position in which limb can be maximally utilized even after its stiffness, e.g., glass-holding position of wrist. This position is used for arthrodesis of a joint.
- Position of immobilization: The position in which the ligaments and tendons around joints remains maximally stretched, so that the contracture of joint could be prevented, e.g., James position of hand (lumbrical plus hand posture).
- The fracture reduction and maintenance under cast also follows the “three-point molding principle of Charley's”. Out of these three points, two points lie proximal and distal to fracture site. The third point lies at the site of fracture site but the direction of molding force working here is opposite to the above two points (Fig. 6).
- Ask the patient to follow the instructions like:
- Keep the limb elevated. Why we ask the patient lying on bed with a cast in his either of the limb to keep over pillow or hang it with some cord or bandage? Just to maintain the limb above the patient heart level to ensure easy venous drainage and this act minimizes the swelling.
- Ask the patient to do finger or toe movement—this improves the circulation in the respective limb and side-by-side keep the muscle active and finally minimize postcast stiffness.
- Removal of cast is done immediately if any sign of cast tightness develops in the limb—like continuous pain, discoloration of finger, etc.
CASTING IN JAMES POSITION (RADIAL GUTTER, ULNAR GUTTER, AND VOLAR SPLINTAGE WITH POP) (FIGS. 7A TO C)
- Position:
- Wrist joint: 30–40° extension
- Metacarpophalangeal joint: 70° flexion
- Proximal interphalangeal joint: 20° flexion
- Distal interphalangeal joint: 10° flexion.
- Extent:
- Proximally: Cover lower two-thirds of forearm
- Distally: Proximal to distal interphalangeal joint.
- Uses:
- Metacarpal fractures
- Proximal phalanx fracture of fingers
- Metacarpophalangeal joint injury
- For preventing clawing
- After tendon repair and tendon transfer.
SCAPHOID CAST AND THUMB SPICA (FIG. 8A)
- Position: Glass holding.
- Extent of cast:
- Proximally: Cover lower two-thirds of forearm
- Distally: Up to proximal palmar crease and proximal to interphalangeal joint of thumb.
- Uses: Fracture of scaphoid.
- Thumb spica (Fig. 8B):
- It maintains the wrist in 10–20° of extension and thumb in slight flexion and palmar abduction.
- It is used for immobilization of thumb in injuries around first carpometacarpal joint, metacarpophalangeal joint, and interphalangeal joint.
COLLES’ CAST (FIG. 9)
- Position:
- Wrist attitude: Approximately 25° ulnar deviation with slight palmar flexion
- Forearm attitude: Full pronation.
- Extent of cast:
- Proximally: Cover lower two-thirds of forearm
- Distally: Proximal to palmar crease in volar aspect and just short of knuckle in dorsal aspect.
- Used:
- For smith fracture:
- Full supinated forearm
- Ulnar deviation and dorsiflexion at wrist
- Extent of cast is above elbow.
- For Barton fracture—volar Barton: Wrist-flexion attitude and in dorsal Barton—wrist-extension attitude.
U-SLAB OR CAST (FIG. 10)
- Position of limb:
- Extent of cast:
- Stretch from inside of arm
- Run around the elbow
- End over the junction of shoulder and neck.
- Uses: For fracture of shaft of humerus.
Note: Secure the upper most part of cast with some strapping or sling extending up to apposite shoulder or chest.
ABOVE ELBOW CAST (FIGS. 11A TO C)
- Position of limb:
- Extent of cast:
- Proximally: Up to mid-arm
- Distally: Just proximal to metacarpophalangeal joint of hand.
- Uses: For fracture of both bones of the forearms.
SHOULDER SPICA (FIG. 12)
- It incorporates trunk with upper limb.
- Position of limb:
- Shoulder abducted: In proximal humeral fractures, shoulder is abducted to such extent that maintain the alignment of distal fragment with proximal fragment.
- Elbow 90° flexed and forearm in mid-prone position.
- Extent of cast:
- Above the waist
- Involve ipsilateral shoulder
- Distal to metacarpophalangeal joint if needed otherwise restrict just proximal to wrist joint.
- There is supporting bar between forearm and trunk.
- Used for:
- Brachial palsy
- Selected cases of proximal humeral fracture dislocation.
BELOW KNEE CAST AND BOOT CAST (FIGS. 13A AND B)
- Position of limb: Ankle slightly plantarflexed.
- Extent of cast:
- Used for:
- Fracture of calcaneum and talus
- Fracture of tarsals and metatarsals
- Sometimes for injury around ankle.
Note: When cast extends below the bulk of calf, it is called boot cast as it looks like the military boot.
CYLINDRICAL CAST (FIG. 14)
- Position of limb: Knee extension
- Extent of cast: High groin to above ankle.
- Uses:
- Acute knee injuries
- Fracture of patella.
ABOVE KNEE CAST (FIG. 15)
- Position of limb:
- Knee: 15° flexion (why?)
- To maintain functional position
- Flexed knee prevent rotation at fracture site.
- Ankle: 10° plantarflexion in upper one-third fracture and 20° plantarflexion in lower two-thirds fracture. Why? It prevents posterior angulation at fracture site.
- Uses:
- For fracture and fracture-dislocation around knee
- For fracture of tibia and fibulae
- For tibial plafond fracture.
CONGENITAL TALIPES EQUINOVARUS CAST: A SPECIAL TYPE OF ABOVE KNEE CAST (FIG. 16)
- Ponseti technique of serial casting for congenital talipes equinovarus (CTEV) correction.
- Position of limb:
- Knee: 90° flexion (why?)
- Prevents slippage of cast
- Relaxes gastrocnemius muscle
- Prevents tibial rotation.
- Ankle and foot: As per sequence of deformity correction in serial casting.
- First midfoot cavus and forefoot pronation
- Then, forefoot adduction and heel varus and equinus
- Finally residual equinus, if any.
- Extent of cast:
- Proximally: Just short of groin
- Distally: Cast is applied in such a way that pulp of toes is covered and dorsum of toes is visible.
PATELLAR TENDON BEARING CAST—A FUNCTIONAL CAST BRACING (SARMIENTO A, 1963) (FIG. 17)
- It is a closed method of fracture treatment, which is complimentary to other methods of fracture management.
- Principle: It is based on the belief that continuing function while a fracture is uniting it does three things:
- Enhances osteosynthesis
- Promotes healing of fracture
- Prevents complication like joint stiffness.
- Mechanism of action of Pascal's law:
- When the limb is loaded, there is generation of intracompartmental pressure around fracture site that exerts pressure on the wall of facial compartment.
- As there is a rigid cast around limb, the similar amount of pressure starts working in opposite direction that maintains the reduction of fracture.
- Prerequisites for patellar tendon bearing (PTB) casting:
- Fracture should be treated first by some conventional methods
- There is no pain at fracture site on minimal movements
- There is no deformity at fracture site
- There should be a reasonable resistance to telescopy
- Shortening should not exceed 0.25” for tibia and 0.5” for femur.
- Used for:
- Fracture of distal femur
- Fracture of proximal tibia
- Fracture of distal tibia
- Fracture of shaft of humerus.
- Contraindications:
- Noncompliant patient
- Neuromuscular disorder
- Altered sensitivity of limb
- Isolated tibia fracture (fibula intact)
- Proximal femur fracture
- Both bones of the forearms fracture
- Monteggia fracture-dislocation
- Galeazzi fracture-dislocation.
WALKING HEEL (RUBBER) (FIG. 18)
- Parts of walking heel:
- Thin peripheral extension
- Two ribbed thickened broad base
- Transverse slot in heel
- Elevated rounded medial ridge for medial arch
- Hole on lateral side to make it lighter.
- Use: In PTB cast. Why? It prevents breakage of plaster cast during weight bearing.
WALKING IRON (FIG. 19)
- Parts of walking iron:
- Metal cross bar
- Metal upright
- Flare (rounded) of side bar
- Terminal part of side bar
- Rubber heel.
- How to apply?
- 2.5 cm below neck of fibulae
- Below knee padding of limb and apply one or two POP bandages over it
- Set the walking iron
- Further wrapping of walking iron with POP bandages.
- Uses: As weight-relieving orthosis.
- Fracture of tarsals and metatarsals
- Fracture of calcaneum and talus.
PIN PLASTER TECHNIQUE (FIG. 20)
- Principle: Stabilization of fracture with cast and Steinmann pin assembly.
- How to apply:
- First pin above fracture and second below fracture, as far as possible
- Achieve reduction
- Cast applied in reduced position
- Minimal joint involvement.
- Advantages of pin plaster technique:
- Prevents joint stiffness
- Early mobilization
- Check rotation.
- Disadvantages of pin plaster technique:
- Loss of reduction
- Pin track infection.
HIP SPICA (FIGS. 21A TO D)
- It encompasses trunk with the lower limb.
- Position of limb:
- Knee: 45° flexion. Why so? Flexion less than 45° may lead to loss of fracture reduction
- Ankle: Neutral position.
- Extent of cast:
- Proximally—extend up to nipple and rest on rib cage. Why? It provides a bony support to the cast and prevents its breakage.
- Distally: On the basis of distal extension of cast, spica can be classified as follows:
- Single hip spica: Involving only one leg and extend up to foot
- One and half spica: Involves one leg up to foot and other leg up to knee
- Double hip spica: Involving both leg up to foot.
- Uses:
- Fracture of femur (shaft and neck) in children
- After closed reduction in developmental dysplasia of the hip
- After pediatric hip surgeries.
- Strengthening of spica:
- By applying POP slabs around hip and thigh
- By wrapping wooden stick with POP bandages between both legs.
- Why we apply soft material between abdomen and cotton padding during spica application?
- Complications:
- Urinary retention
- Plaster cast syndrome (PCS)—a constellation of symptoms—like pernicious vomiting, pain in abdomen, and abdominal distension; developed soon or later after application of spica is called plaster cast syndrome.
The underlying pathology is obstruction of third part of duodenum in between aorta and superior mesenteric artery. Treatments given are:
- Immediate removal of spica
- Stop oral intake
- Intravenous fluid infusion
- Antiemetics
- Antacids
- Gastric decompression by nasogastric tube
- Serum electrolyte monitoring
- Severe cases of laparotomy. PCS was common in the past when scoliosis was corrected with Harrington rod.
- Immediate hip spica application:
- Indication: Fracture of shaft of femur in children <5–6 years of age with shortening less than 2 cm.
- Complications:
- Compartment syndrome
- Loss of reduction
- Angulation
- Shortening.
- To reduce the rate of complication, the 90–90° position of hip and knee is used but it can be applied only for age less than 2–3 years due to fear of neurologic complication.
Note: Normally, hip spica is applied after keeping the pediatric fracture of shaft of femur under 3 weeks of skin traction (<5 years) or skeletal traction (>5 years) because during these period, acceptable reduction is achieved and fracture becomes sticky also. By this way, above complications can also be minimized.
- Hip spica in human position for developmental dysplasia of the hip (DDH):
- Position: 95° flexion at hip joint and 40–45° abduction at hip joint.
- Advantages of human position:
- Stability at hip
- Decreased risk of osteonecrosis of head of femur.
WEDGING OF CAST (FIG. 22)
- How much correction by wedging: Only 10–15° angulation should be corrected by wedging.
- Timing of wedging: Wedging should be done as soon as possible (2–3 days). Once the fracture becomes sticky, it prevents the lateral motion at fracture site.
- How wedging is done: Five steps—
Identification of the site of wedging
↓
Do circumferential slitting of cast just opposite to the site of angulation
↓
At least one-fourth of circumference of cast should be left
↓
Hold the wedging of cast with a block and repair the cast with POP bandage
↓
Final reduction is checked under X-ray
MAKING A WINDOW IN CAST (FIG. 23)
- Timing of making window: When plaster becomes fully dried.
- Indications:
- For frequent inspection of wound
- For stich removal.
- Identification of window making site:
- By overpadding to produce bulging at window site
- By measuring the wound site from fixed bony point.
- How window is made:
Apply plaster cutting saw on marked area
↓
Elevate the window out of the cast
↓
Remove the underlying padding
↓
Inspect the wound
↓
Replace the padding and keep the window in place
↓
Apply cotton bandage over window or repair with POP bandage
BIVALVING OF CAST (FIG. 24)
- A method of cast removal when whole cast is removed in two parts.
- When to do bivalving:
- If there is need of frequent observation of fracture site, e.g., in case of compound fractures
- Where there is risk of compartment syndrome
- For removal of fiberglass cast.
- For example, in case of below knee cast, cut the cast posterior to medial malleoli in medial side and anterior to lateral malleoli in lateral side in vertical plane.
SLITTING OF CAST (FIG. 25)
- Indication of slitting of cast: When a POP cast is applied over a limb, it shows any one of the following features as:
- How to slit a cast:
Make a marking of slitting overt cast
↓
With the help of electric or manual, saw a straight cut is made in long axis of limb
↓
Slit directly up to underlying padding of cast and remove the cotton paddings, so that limb could be directly visible
↓
Now apply a bandage around slitted cast to just keep it in place, i.e., here POP cast is acting as splint only
CHECKLIST FOR CASTING
- Extent of cast
- Position of limb
- Alignment of limb
- Smoothness/irregularity of cast
- Cracks over cast
- Any sign of tight plaster.