Topical PDGF (Regranex®) Versus Placebo
Therapy of Diabetic Foot Ulcers Off-Loaded
with Windowed Casts, a Randomized,
Controlled Trial.
METHOD FOR CONSTRUCTING
WINDOWED SHORT LEG CASTS
WINDOW CASTING
The basic design for casts employed in this study was based on the standard padded short leg
walking cast. Our windowed casts had five layers [see next slide] starting with the skin: 1] a
thick hydrocolloid protective layer applied directly to the skin around the wound (Duoderm
CGF® - Convatec); 2] a cotton tubular roll gauze (Stockinette® - Alba Health); 3] water resistant
foam padding (1/8” Delta Terry-Net™ Adhesive Terry Cloth / Foam Padding, Charlotte, NC); 4]
cotton roll cast padding (Webril® -Kendall); 5] 3M™ Scotchcast Plus -4” fiberglass. In most
cases a toe plate type cast was employed allowing toes more freedom of motion and exposure,
but in some instances the forefoot was sealed completely within the cast. In a few instances, for
example with Charcot deformity or transmetatarsal amputation, rubber plantar bars were fixed to
the bottom of the cast, but in most cases only a standard cast shoe was dispensed to protect the
bottom of the cast.
WINDOWED CAST COMPONENTS
TELFA
WEBRIL
FIBERGLASS
CAST PLUG
MOIST GAUZE
STOCKINETTE
DUODERM
WOUND
SKIN
QUICKSTICK
PADDING
Side View of Cast
Nail and padding
For routine application the following steps were followed:
1] Clean the skin to be incorporated in the cast with warm water, dry the skin, and apply
petrolatum from knee to ankle.
2] Apply Duoderm CGF® starting close to the wound perimeter and extending approximately
1.5” away from the wound. The area of the wound is exposed via a cut-out in the Douderm
CGF®. This step is aimed at protecting the surrounding skin from moisture maceration. In
wounds with excessive drainage, application of the Duoderm CGF® several inches away from
the wound may be necessary to sufficiently protect a larger area of skin.
3] Use 3” or 4” Stockinette® to cover the foot, ankle, and leg with 6-8 inches additional on the
distal end. Use extra Stockinette® proximally to allow roll-back of Stockinette® at this end.
Accommodate ankle dorsiflexion with a transverse cut from malleolus to malleolus
andoverlapping of the cut edges. Determine the exact location of the wound under the
Stockinette®.
4] Place the foam padding over boney prominences including but not limited to the heel, the
malleoli, and the anterior aspect of the tibia. This padding protects the skin from shearing and
cast burns over boney prominences.
5]Cut a square piece of foam padding approximately 0.5 x 0.5 inches larger than the wound.
Make a hole in the Stockinette® slightly larger than the wound and place directly over the center
of the wound and attach it to the Duoderm® with the adhesive backing, moving the Stockinette®
away. This step completes a picture frame centered around the wound comprising an inner layer
of Duoderm CGF® and an outer layer of foam padding.
6] A pre-made square of padded foam with a sterilized 1” large head anodized roofing nail
sticking up out of the padded foam is placed in the center of the wound with the nail spike
pointed perpendicular to the wound surface. The nail spike will serve later as a marker buoy to
guide cutting of the fiberglass plug. This step is employed when necessary for small wounds to
accurate determine where to cut out the window (see step 13).
7] Apply three layers of Webril® padding extending from the heel to the dorsum of the foot,
starting a the distal end, wrapping the foot and ankle. Make sure the nail spike is exposed outside
the Webril®. Apply an additional three layers of Webril® from the dorsum of the foot to the
proximal end of the Stockinette ® . Continue to wrap the leg to create generous padding using
50% overlap of the Webril®
8]. Moisten and apply the first roll of fiberglass starting on the lateral aspect of the foot. Apply
two layers around the medial and lateral aspects. Wrap the dorsum of the foot and ankle. Apply
the second roll of fiberglass starting at the distal end of the cast, wrapping the foot again and
advancing to the intended proximal margin at the middle of the leg.
9] Position the ankle and foot in the desired position (usually neutral) by molding the plantar
surface of the foot and all other landmarks of the ankle and leg. Start the third roll of fiberglass
by fan folding four to five layers to create a reinforcing plantar fiberglass splint from heel to toe.
Secure the fiberglass splint with the remainder of the third roll starting at the heel, wrapping the
fiberglass in a spiral fashion all the way to the proximal margin of the cast.
10] Recheck the molds and make adjustments as needed. Check the molding of the leg and fold
excess Stockinette ® and Webril® proximally and distally (if a toe plate type cast is constructed)
over the fiberglass.
11] Take care to keep the marker nail spike exposed outside the Webril® and fiberglass during the
steps 7-10.
12] Trim the fiberglass and Webril® toe plate area so that it is ½ to ¾’’ longer than the hallux.,
and trim the distal end to close to the 5th toe. Fashion an even line to maintain a smooth and well
shaped finish cut. Secure the folded edges of Webril® and Stockinette® with tape to the
fiberglass. Fold the proximal end of the cast down to make a soft circumferential dege. Apply a
final layer of fiberglass to complete the cast.
13] Use a Sharpie® pen to mark the cast material for removal centered around the protruding
nail spike. Cut out a squared window (cast plug) with a cast saw. Carefully pull on the nail to
remove the cast plug. Remove the nail from the cast plug .) Remove or trim excess any excess
Webril ® to expose the wound. It is important that when the cast plug is reinserted after dressing
the wound that it not protrude above the level of the cast, particularly if the wound is over a
weight bearing surface, as this will counteract off-loading . When plantar bars are employed a
cast plug is not necessary, and the window may be sealed with tape between dressing changes.
14. Apply study medication and dress the wound with saline moistened 2x2” or 4x4” gauze
(depending on wound size) and then a piece of Telfa®. The surface of the dressing should be
flush with the surface of the Webril® layer of the cast. Place the cast plug back into the window
and secure with tape.
15. Fit the patient with an appropriate cast shoe.
Stockinette and
Foam padding
applied
All Webriil
applied
Picture framing wound
before Webril®
First layer of fiberglass
Applying Webril®
Molding plantar aspect
of fiberglass
Plantar and medial-layer fiberglass
reinforcement applied (arrows) for
toe plate
Cutting out the toe plate
Cutting out the toe plate
Finished short leg cast
With toe plate
Heel cut out for window
over ulcer
Before treatment
In windowed cast
Healed
In windowed cast
Before
In windowed cast
Healed
During treatment
Initial wound
Healed at week 5
Before