2 Cast Modifications

Cast Modification Process

1. Gather tools/materials: surform, utility knife, plaster bowl, regular screwdriver, and measurements of residual limb
2. Remark bony prominences
3. Compare the length and M/L measurements on your mold with the prosthetic measurement form.
4. Draw the trimlines

   • 	Medial Trimline	Lateral Trimline	Posterior Trimline	Anterior Trimline
     Flexible Hinges	Follows a gentle arc to the anterior while allowing maximum supination (ending posterior to the medial epicondyle)	Follows a gentle arc to the anterior while allowing maximum pronation (ending posterior to the lateral epicondyle allowing)	Encompass the olecranon for protection	Cubital fold
     Rigid Hinges	Encompasses the medial humeral epicondyle	Encompasses the lateral humeral epicondyle

5. With surform, slightly flatten and flare the anterior-proximal area of the model to provide total surface contact between the limb and the socket. Remove only enough to conform to the circumference measurements.
6. Buildups: do not make a sharp point on the buildups. Follow the shape of the bones and consider how the bone changes shape through elbow ROM. You may use a tack or a staple to gauge the correct distance for the buildups.
   

   

   1. 3mm over styloids, if present
   2. 6mm distally over the ends of the bony projections.
   3. 6-10mm over olecranon at a 45’ angle. Cover the full medio-lateral width of the olecranon maintaining its natural contour. Notice how the olecranon changes it proximal-distal shape as the elbow flexes and extends. The most proximal-posterior portion of the socket should fit into the triceps tendon (triceps bar) when the elbow is fully extended.
   4. 6mm medial epicondyle
   5. 3mm lateral epicondyle. Consider the prominence of your patient’s supracondylar ridge.
   6. Proximal to epicondyles to allow donning/doffing

7. If a window is needed to accommodate a bulbous end, measure the width of the styloids on the model with calipers. Set the calipers at this width then move them proximally until the same width is reached. The window will extend between the two widest areas of the mold.