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Nonunion

Nonunion. 主讲教师 : 欧阳宏伟 / 蔡友治. 浙江大学医学院. Femoral Neck Nonunion. Definition: not healed by one year 0-5% in Non-displaced fractures 9-35% in Displaced fractures Increased incidence with Posterior comminution Initial displacement Inadequate reduction Non-compressive fixation.

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Nonunion

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  1. Nonunion 主讲教师:欧阳宏伟/蔡友治 浙江大学医学院

  2. Femoral Neck Nonunion • Definition: not healed by one year • 0-5% in Non-displaced fractures • 9-35% in Displaced fractures • Increased incidence with • Posterior comminution • Initial displacement • Inadequate reduction • Non-compressive fixation

  3. Clinical presentation Groin or buttock pain Activity / weight bearing related Symptoms more severe / occur earlier than AVN Imaging Radiographs: lucent zones CT: lack of healing Bone Scan: high uptake MRI: assess femoral head viability Femoral Neck Nonunion

  4. HOW TO HEAL

  5. Mechanism

  6. Mechanism Normal healing

  7. Stages of long bone healing

  8. Time course of fracture healing Caranoa RAD, Filvaroffb EH. Angiogenesis and bone repair. Drug Discovery Today. 2003;8(21): 980–989

  9. Metaphyseal bone healing process Contact healing Gap healing

  10. Inflammation and repair Claes, L. et al. (2012) Fracture healing under healthy and inflammatory conditions Nat. Rev. Rheumatol.

  11. Main factors affecting healing

  12. Biomechanical mechanism

  13. Mechanism

  14. Mechanism Nonunion Lack of fusion Normal healing

  15. Definition • FDA defined nonunion as “established when a minimum of 9 months has elapsed since fracture with no visible progressive signs of healing for 3 months” • Every fracture has its own timetable (ie long bone shaft fracture 6 months, femoral neck fracture 3 months)

  16. Etiology • Do not blame the osteoblasts (Watson Jones). • Fractures have a spontaneous tendency to heal. (Merle D’Aubigne). • Delayed or non-union is often multifactorial in nature. • Disturbed vascularity and instability are the most important factors leading to a non-union. • Biological：Neck of the femur

  17. Nonunion Nonunited fractures form two types of pseudoarthrosis: • Hypervascular or hypertrophic With biological reaction capacity • Avascular or atrophic Without biological reaction capacity

  18. Judet-Weber classification • Hypervascular or hypertrophic non-union • They do not heal because of instability

  19. Judet-Weber classification • Avascular or atrophic non-union • They do not heal because of biological deficit

  20. A. Hypervascular or Hypertrophic nonunion • Elephant foot (hypertophic, rich in callus) • Horse foot (mildly hypertophic, poor in callus) • Oligotrophic (not hypertrophic, no callus)

  21. Elephant foot Horse hoof Oligotrophic A. Hypervascular or Hypertrophic nonunion

  22. Hypertrophic non-union • Hypertrophic non-union is frequently localized in the lower extremities. • Its development largely depends on an impaired mechanical stability.

  23. Pathology

  24. Pathology

  25. Pathology

  26. Bone healing by mechanical stabilization

  27. Calcifying focus Non-union focus Ca. marked fracture site

  28. Ca. marked fracture site Totally calcified focus Fracture healing trabeculae

  29. Stabilized fracture evolution • Mechanical stability allows the fibrous cartilage to calcify and finally ossify after vascular penetration. • Resection of an hypertrophic non-union must be regarded as an error.

  30. Instability (non-union)

  31. 8 m 4 m Stabilization (bone healing)

  32. B. Avascular or Atrophic nonunion • Torsion wedge (intermediate fragment) • Comminuted (necrotic intermediate fragment) • Defect (loss of fragment of the diaphysis) • Atrophic (scar tissue with no osteogenic potential is replacing the missing fragment) • Avascular nonunions. A, Torsion wedge nonunion. B, Comminuted nonunion. C, Defect nonunion. D, Atrophic nonunion (see text). (Redrawn from Weber BG, Cech O, eds: Pseudarthrosis, Bern, Switzerland, 1976, Hans Huber.) A B C D

  33. B. Avascular or Atrophic nonunion • Avascular non-union originates because of the devascularisation of the bone fragments adjacent to the fracture site due to injury and/or surgery.

  34. Devitalized fragments united by callus to the main fragments without evidence of bone healing B. Avascular or Atrophic nonunion

  35. Nonunion Treatment: • Biotherapeutics: PRP • Elecrical • Electromagnatic • Ulrasound • External fixation • Surgical • Hypertrophic: stable fixation of fragments • Atrophic: decortication and bone grafting • According to classification: type A : restoration of alignment, compression type B : cortical osteotomy, bone transport or lengthening

  36. Nonunion Surgical guidelines: • Good reduction • Bone grafting • Firm stabilization

  37. Nonunion Bone Grafting origins: • Autogenous “the golden standard” • Allograft • Synthetic substitute

  38. Treatment

  39. Special Problems Stress Fractures • Patient population: • Females 4–10 times more common • Amenorrhea / eating disorders common • Femoral BMD average 10% less than control subjects • Hormone deficiency • Recent increase in athletic activity • Frequency, intensity, or duration • Distance runners most common

  40. Cause • Change in load • Small number of repetitions with large load • Large number of reps, usual load • Intermediate combination of increased load and repetition

  41. Pathophysiology • Wolff’s Law: change in external stress leads to change in shape and strength of bone • bone re-models in response to stress • ABRUPT Increase in duration, intensity, frequency without adequate rest (re-modeling) • Stress fracture: imbalance between bone resorption and formation • Microfracture -> continued load -> stress fracture

  42. Risk factors • History of prior stress fracture • Low level of physical fitness, non-athlete • Increasing volume and intensity • Female Gender • Menstrual irregularity • Diet poor in calcium • Poor bone health • Poor biomechanics

  43. Risk factors • Prior stress fracture: • 6 x risk in distance runner and military recruits • 60% of track athletes have hx of prior stress fracture • One year recurrence: 13% • Poor Physical Fitness - muscles absorb impact • >1cm decrease in calf girth • Less lean mass in LE • Less than 7 months prior strength training

  44. Intrinsic factors • Extreme arch morphologies: • Pes cavus • Pes planus • Biomechanical factors: • Shorter duration of foot pronation • Sub-talar joint control • Tibial striking torque • Early hindfoot eversion

  45. Extrinsic factors • Activity type and intensity • Footwear • Older shoes • Shock absorbing cushioned inserts • Running Surface • Treadmill • Track

  46. Ballet: Runners: Sprinters: Long dist runner: Baseball, tennis: Gymnasts: Rowers, golfers: Hurdlers: Rowers, Aerobics: Bowling, running: Associations Lumbar, femur, metatarsal Tibia, metatarsal Navicular Femoral neck, pelvis Humerus Spine, foot, pelvis Ribs Patella Sacrum Pelvis

  47. Stress FracturesComplications • Tension sided and Compression sided fx’s (>50%) treated non-operatively • Varus malunion • Displacement • 30-60% complication rate • AVN 42% • Delayed union 9% • Nonunion 9%

  48. 讲者简介 蔡友治 03级临床七年制 浙大附属第一医院骨科运动医学中心 医生 专注于运动创伤微创诊治及创新性医疗手段的研发. 目前在干细胞及纳米组织工程领域有一定深入研究。 发表SCI及中华医学期刊十几篇，负责国家自然科学基金一项（在研），并参与多项科研基金。 Email：caiyouzhi1985@gmail.com TEL： 13588270341 运动让生命更健康 医学让运动更美好

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