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Femoral Neck Fractures

Femoral Neck Fractures. 主讲教师 : 欧阳宏伟 / 蔡友治. 浙江大学医学院. High energy injury. Low energy injury. Case 1. An 81-year-old Female complaining of hip pain and inability to walk after a simple fall. Case 2. A 47-year-old female with a history of schizophrenia and alcoholism

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Femoral Neck Fractures

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  1. Femoral Neck Fractures 主讲教师:欧阳宏伟 / 蔡友治 浙江大学医学院

  2. High energy injury

  3. Low energy injury

  4. Case 1 • An 81-year-old • Female • complaining of hip pain and inability to walk after a simple fall.

  5. Case 2 • A 47-year-old • female • with a history of schizophrenia and alcoholism • complaining of hip pain and inability to walk after a fall. • The affected leg appeared slightly shorter than the contralateral leg, and any attempted movement was painful.

  6. 82-year-old • female • complaining of hip pain after an unwitnessed fall. Case 3

  7. Case report • A girl fall from a high tree • Result: simultaneous bilateral fractures of the femoral neck • process: initially they fall on edge of the roof or on branch of tree fracturing one neck of femur before falling to the ground to fracture the other. How happened?

  8. Physeal closure age 16 Neck-shaft angle 130° ± 7° Anteversion 10° ± 7° Calcar Femorale Posteromedial dense plate of bone Anatomy

  9. Anatomy anteversion

  10. Anatomy calcar femorale

  11. Anatomy

  12. Blood Supply • Intracapsular are at risk of non union and avascular necrosis due to interruption of the blood supply to the femoral head • Via cruicate (med and lat circumflex) and intramedullary.

  13. Muscular balances

  14. Muscular balances

  15. Muscular balances

  16. Muscular balances

  17. Muscular balances in hip

  18. What’s the mechanism?

  19. Bone Load and Response • Stress • force per unit area • Strain • deformation • amount of deformation divided by original length

  20. Types of Forces • Tensile • Compressive • Bending • Shear • Torsion

  21. Compressive Loading(pushing, compressing forces)

  22. Stress, or pressure (s): force per unit area How much force does it take to cause an effect? That depends on how much area the force is spread over.

  23. Localize Force with Pisiform Contact (Greater stress because contact area is smaller)

  24. The concept of strain also applies to compressive loads L - DL- If the original length (L) was 300 mm and the new length was was 291 mm then e = DL / L =(new length – original length) / original length e = (291 mm – 300 mm) / 300 mm = -9 / 300 e = -0.03, or -3% Strain by itself tells you nothing about stress

  25. Compressive load compression fracture Bilateral Compression of Femoral Necks Compression Fracture of C5

  26. Stress-Strain Relationship Generic Plastic Region Elastic Limit Stress (load) Elastic Region Strain (deformation)

  27. Stress-Strain Relationship Bone Plastic Region Stress (load) Fracture Threshold Elastic Region Strain (deformation)

  28. Relative Bone Strength Compression Tension Shear Fractures: with excessive loads, bone tends to fracture on the side loaded in tension.

  29. Bone Response to Stress • Wolff's law (1892) • tissue adapts to level of imposed stress • increased stress • hypertrophy (increase strength) • decreased stress • atrophy (decrease strength) • Shape reflects function • Genetics, Body weight, physical activity, diet, lifestyle (see note clippings)

  30. Protecting our Bones in Sport

  31. The pattern of • Trbecular bone • in the • greater trochanter • neck of the femur • head of the femur • reflects femur’s roles: • muscle attachment • flexibility • weight transfer • support

  32. Atrophy in Bone • Weight & strength decrease • Calcium content diminishes • Reduced BMD • Trabecular integrity is lost

  33. Bone stimulating factors • Rate of loading • Magnitude • Frequency

  34. BMD and walking Quartiles based on miles walked/week Krall et al, 1994, Walking is related to bone density and rates of bone loss. AJSM, 96:20-26

  35. Biomechanics

  36. Biomechanics One mechanism for reducing the resultant load on the femoral head is the use of a walking stick in the opposite hand.

  37. Biomechanics of Cane • Cane in Contralateral hand decreases JRF • Long moment arm makes so effective • 15% BW to cane reduces joint contact forces by 50%

  38. Fracture mechanism

  39. Fracture mechanism

  40. Fracture mechanism

  41. Fracture mechanism

  42. Fracture mechanism

  43. Fracture mechanism

  44. Blood supply insufficiently

  45. Fracture mechanism

  46. Garden Classification • Garden I: incomplete fracture of the femoral neck • Garden II: complete fracture without displacement • Garden III: complete fracture with partial displacement • Garden IV: complete fracture with full displacement

  47. Fracture of femur neck • Geriatric population – simple fall • Younger population – high energy injury

  48. Risk Factors • Age: >65 years • Co-morbid factors: osteoporosis, endocrine disorders (hyperthyroidism, hypogondaism), GIT disorders interfering with calcium/ Vit D absorption, neurological disorders (Parkinsons, MS) • Gender: F • RTA

  49. Risk Factors • Nutrition: lack of calcium and Vit D in diet, eating disorders (anorexia), high caffeine intake • Smoking • Alcohol • Medication: steroids, anticonvulsants, diuretics • Environmental factors: loose rugs, dim lighting, cluttered floors

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