1. Aim 1: Provide Immediate Support  Basic Design  Fix joint using scaffold  Fill in the bone cavity completely.  Match shape using CT scan  Exact shape discussed later  Need extra support around the edges  Metal Socket and contact with bones.

2. Aim 1: Provide Immediate Support  Extra support comes from BMP in scaffold  Most dense around the critical area  Fastest bone growth in critical area

3. Aim 1: limitations and failures  Forces on joint not always in one direction  For sake of discussion, think 2D first.  Force acting on center of the scaffold in the direction of the femoral neck is risky  May not always be safe for immediate walking for the patient

4. Aim 1: Alternative approach  Redistribute BMP gradient  Extra “pillar” in the affected region.  Supports the weight applied through the ball joint better.

5. Aim 2: provide improved bone growth  Design  BMP must cover all area by matching the patient’s bone shape  Use CT scan  Rapid prototype the scaffold.  BMP must avoid reconstructing bone too quickly  Osteoblasts and Osteoclasts  Rapid Prototyping  Cannot just “print” the scaffold  Using casting method

6. Aim 2: provide improved bone growth  As mentioned before…  BMP gradient  Most dense area used for immediate support  Least dense area used for slower but complete bone growth in inner region  Go slow to reduce risk!

7. Aim 2: Limitations and Failures  Limitation in using BMP  BMP may not be suitable for all patients  Case: patients with extra large amount of bone loss  Proportionally, these patients will lose more osteoblasts  Alternate approach  Attempt reducing amount of BMP used.  No change in gradient  Reduce overall usage of scaffold

8. Aim 2: Limitations and Failures 2  Limitation in application  The scaffold match patient’s bone by shape, but how to match it physically?  There are some case where you cannot physically insert the scaffold

9. Aim 2: Alternate Approach 2  “Simplify” the shape of the cavity using cement  Would require trimming of scaffold  Double CT scan may be necessary

10. Aim 2: Limitations and Failures 3  Limitation in application  Can fail to insert it into patient if correct rotation is not recorded

11. Aim 2: Alternate Approach  Limitation in application  Not so bad.  Would need another device to correctly store the rotation in z-axis for the scaffold  Or make an “indicator” on the scaffold during rapid prototyping process.

12. Aim 3: Reduce Overall Number of Surgeries  1. Successful bone growth would reduce risk of returning to the hospital  2. Removing need to remove any of the component of scaffold reduce risk and need of returning to the hospital  Achieved this by making the scaffold using biodegradable material

13. Aim 3: Reduce Overall Number of Surgeries  Recall  Rate of bone growth = Rate which scaffold bio-degrades  Scaffold completely gone without causing excessive volume of BMP + scaffold in the joint for the patient  Limitations and Failures  Scaffold itself is not in gradient  At one point in time or space, amount of scaffold remaining may too little to hold BMP

14. Aim 3: Alternative Approach  Lower rate of bone growth  Reduce overall density of BMP in scaffold  It is safer if the scaffold remains a little bit longer than necessary