1. Orthopedic Biomechanics 沈文哲 台灣 高雄市 博正醫院

2. Course Objectives Why are we studying this? Terminology Understanding the condition Management of fractures Design and application of implants

3. Stress Strain Curve Strain

4. Load Deformation Curve

5. Creep

6. Tension band Converts tension forces into compression forces

7. Which is Strongest? How many twists are needed?

8. Which hand do you hold the cane? 1) Rt side 2) Left side 3) No difference 4) Depends on the lumbar spine status Osteonecrosis Rt hip is painful

9. The Non-Painful Side

10. Which leg goes first when climbing stairs? Rt knee is painful

11. 好腳上天堂, 壞腳下地獄 Painful knee kept straight.

12. Which brace to order?

13. Think of the Forces 3-point fixation

14. Where to place the knot? Submandibular position “long drop” 83kg – 173 cm 51kg – 244 cm hyperextension distraction

15. Deforming Forces

16. Fracture Patterns AO classification (Muller)

17. Different Forces

18. Classification Based on Mechanism of Injury Allen classification of cervical spine injuries

19. Plate Fixation 6 wks3 mo1 yr

20. A Load Bearing Construct 1 mo12 mo

21. How long a plate? What kind of screw? Lag screw

22. What angle? Where to put the plate?

23. Placement of Implant

24. How long? How thick? Titanium? Solid? Cross section? Fluted? Tapered? Bowing? Reaming? Interlocking? Cost!

25. Stress risers Removal?

26. Load Sharing and Stress Shielding Re-fracture

27. Wolff’s Law Bone deposits along lines of stress transmission

28. External Fixators Rubber band

29. Fixator Design

30. Hip Screws Gamma nail

31. Choice of Implant

33. Hip Prosthesis

34. Choices of Stem

35. Modularity

36. Knee Prosthesis

39. “ 軟骨凸出壓迫神經 ”

40. Rank the intradiscal pressures Bending forward at waist Squatting Sitting Standing Supine

42. Herniated Disc

43. How big can you make the hole? 1) 75% of lamina 2) 50% of lamina 3) 75% of facet 4) 50% of facet 5) 25% of facet

44. Spondylolisthesis Reduction flexion

45. Missing Anterior Strut

46. Fatigue Failure of the Screw

47. Fusion Cage 椎籠 “ 子彈 ” Anterior Strut Only

48. Does Not Resist Extension Forces

49. 40% Failure Rate Biomechanically, an anterior strut requires posterior support. “Supported on two rollers”

50. Combined Ant/Post Fusion

51. Stress Transfer 6 wks post-op 2 yrs post-op

52. 13+2 ♀ Menarche: 6 mo Risser II

53. 13+2 ♀ 7

55. 3-D Vector Analysis Instrumentation design Translate or Rotate?

57. 13+2 ♀

58. Thank You!