Nonunion

主讲教师 : 欧阳宏伟 / 蔡友治

浙江大学医学院

Definition: not healed by one year0-5% in Non-displaced fractures9-35% in Displaced fractures Increased incidence with

– Posterior comminution– Initial displacement– Inadequate reduction– Non-compressive fixation

Femoral Neck Nonunion

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

HOW TO HEAL

Mechanism

Mechanism Normal healing

Stages of long bone healing

Time course of fracture healing

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

Metaphyseal bone healing process

Contact healing

Gap healing

Inflammation and repair

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

Main factors affecting healing

Biomechanical mechanism

Mechanism

Mechanism

Lack of fusion

Normal healing

Nonunion

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)

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

Nonunion

Nonunited fractures form two types of pseudoarthrosis:

• Hypervascular or hypertrophic

With biological reaction capacity

• Avascular or atrophic Without biological reaction capacity

A. Hypervascular or hypertrophic non-union– They do not heal because of instability

Judet-Weber classification

B. Avascular or atrophic non-union– They do not heal because of biological deficit

Judet-Weber classification

A. Hypervascular or Hypertrophic nonunion

1. Elephant foot (hypertophic, rich in callus)

2. Horse foot (mildly hypertophic, poor in callus)

3. Oligotrophic (not hypertrophic, no callus)

Elephant foot Horse hoof Oligotrophic

A. Hypervascular or Hypertrophic nonunion

Hypertrophic non-union

• Hypertrophic non-union is frequently localized in the lower extremities.

• Its development largely depends on an impaired mechanical stability.

Pathology

Pathology

Pathology

Bone healing by mechanical stabilization

Ca. marked fracture site

Non-union focus Calcifying focus

Totally calcified focus

Fracture healing trabeculae

Ca. marked fracture site

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.

Instability (non-union)

Stabilization (bone healing)

4 m 8 m

• 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.)

B. Avascular or Atrophic nonunion

A B C D

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.

Devitalized fragments united by callus to the main fragments without evidence of bone healing

B. Avascular or Atrophic nonunion

Treatment:1. Biotherapeutics: PRP2. Elecrical3. Electromagnatic4. Ulrasound5. External fixation 6. 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 le

ngthening

Nonunion

Surgical guidelines:

• Good reduction

• Bone grafting

• Firm stabilization

Nonunion

Nonunion

Bone Grafting origins:

• Autogenous “the golden standard”

• Allograft

• Synthetic substitute

Treatment

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

Special Problems

CauseCauseChange in load

– Small number of repetitions with large load

– Large number of reps, usual load

– Intermediate combination of increased load and repetition

PathophysiologyPathophysiology

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

Risk factorsRisk factorsHistory of prior stress fractureLow level of physical fitness, non-athlete Increasing volume and intensityFemale GenderMenstrual irregularityDiet poor in calciumPoor bone healthPoor biomechanics

Prior stress fracture: – 6 x risk in distance runner and military recruits– 60% of track athletes have hx of prior stress fractu

re– 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

Risk factorsRisk factors

Intrinsic factorsIntrinsic 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

Extrinsic factorsExtrinsic factorsActivity type and intensity

Footwear– Older shoes

– Shock absorbing cushioned inserts

Running Surface– Treadmill

– Track

AssociationsAssociationsBallet:Runners:Sprinters: Long dist runner:Baseball, tennis: Gymnasts: Rowers, golfers:Hurdlers:Rowers, Aerobics:Bowling, running:

Lumbar, femur, metatarsalTibia, metatarsalNavicular Femoral neck, pelvisHumerusSpine, foot, pelvisRibsPatellaSacrumPelvis

Tension sided and Compression sided fx’s (>50%) treated non-operatively

• Varus malunionDisplacement

– 30-60% complication rate• AVN 42%• Delayed union 9%• Nonunion 9%

Stress Fractures Complications

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