8 Cast Modifications
Cast Modification Process
- Gather materials
- Cast
- Measurement sheet
- ML gauge and tape measure
- Utility knife
- Indelible pencil
- Surforms
- Screen
- Plaster bowl
- Plaster knife
- Plaster
- Remove wrap and assess mold
- Cut down the side with a utility knife or cast saw, taking care not to damage the cast. Strip the wrap and re-mark the landmarks that have transferred from the wrap to the mold
- Measure circumferences, length and medio-lateral dimensions on the model and compare them to your recorded measurements.
- Draw trimlines
| Trimlines | |
| Medial / lateral | Finger width proximal to boney edge of epicondyles
Encompass the epicondyle at the level of the P-M-L with enough of a brim to flare out of the soft tissue. Lateral: relief for the humerus in the ROM (“fan relief”) |
| Anterior | Medium length limbs: 10mm distal to cubital fold
• short limbs closer to cubital fold • longer limbs a little further Biceps tendon located at the anterior brim |
| Posterior | 1” proximal to edge of olecranon, capture the triceps bar
Encompass the olecranon Compression on the triceps tendon Relief for bony pressure on the posterior humeral epicondyles |
- Remove plaster
- Remove plaster from area superior to the epicondyles to gain medio-lateral stabilization
- 6mm proximal to the epicondyles, but allow channel for donning/doffing
- 3mm proximal to the olecranon
- Anterior trimline
- Use a surform to shape and smooth the model
- Add plaster
-
Location Add plaster Antecubital bulge Apex of belly is 1.25-2cm distal to trimline Depends on length of limb
Epicondyles 3mm and lateral relief, fan shape Olecranon 3mm Distal end 6mm Fill holes over bony prominences
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- Reassess mold
- Double check for the following:
- a) pressure distribution to secure the socket at necessary locations (i.e., force couples)
- b) ML dimension at epicondyles to ensure donning/doffing ability and
c) Smooth transition, especially between the head of the radius and the lateral epicondyle and the olecranon and medial epicondyle.
- Smooth the model with sanding screen to remove irregularities.
- Draw trimlines again.