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

• An 81-year-old • Female• complaining of hip

pain and inability to walk after a simple fall.

Case 1

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.

Case 2

Case 3 82-year-old

female

complaining of hip pain after an unwitnessed fall.

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?

Anatomy

Physeal closure age 16 Neck-shaft angle 130° ± 7° Anteversion 10° ± 7° Calcar Femorale

– Posteromedial– dense plate of bone

Anatomy

anteversion

Anatomy

calcar femorale

Anatomy

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.

Muscular balances

Muscular balances

Muscular balances

Muscular balances

Muscular balances in hip

What’s the mechanism?

Bone Load and Response

•Stress– force per unit area

•Strain– deformation

• amount of deformation divided by original length

Types of Forces

TensileCompressiveBendingShearTorsion

Compressive Loading(pushing, compressing forces)

Stress, or pressure (): force per unit areaHow much force does it take to cause an effect?

That depends on how much area the force is spread over.

Localize Force with Pisiform Contact

(Greater stress because contact area is smaller)

The concept of strain also applies to compressive loads

LL

If the original length (L) was 300 mm and

the new length was was 291 mm then

= L / L = (new length – original length) / original length

= (291 mm – 300 mm) / 300 mm = -9 / 300

= -0.03, or -3%

Strain by itself tells you nothing about stress

Compressive load compression fracture

Compression Fracture of C5 Bilateral Compression of Femoral Necks

Stress-Strain Relationship

Strain (deformation)

Str

ess

(loa

d)El

astic

Reg

ion

Elastic Limit

Plastic Region

GenericGeneric

Stress-Strain Relationship

Strain (deformation)

Str

ess

(loa

d)E

last

ic R

egio

n FractureThreshold

Plastic Region

BoneBone

Relative Bone StrengthS

tres

s to

Fra

ctu

re

Load Type

Com

pres

sion

Ten

sion

She

arFractures: with excessive loads, bone tends to fracture on the side loaded in tension.

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)

Protecting our Bones in Sport

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

Atrophy in Bone

Weight & strength decreaseWeight & strength decrease– Calcium content diminishesCalcium content diminishes

• Reduced BMDReduced BMD– Trabecular integrity is lostTrabecular integrity is lost

Bone stimulating factors

Rate of loadingMagnitudeFrequency

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

Biomechanics

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

Biomechanics

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%

Fracture mechanism

Fracture mechanism

Fracture mechanism

Fracture mechanism

Fracture mechanism

Fracture mechanism

Blood supply insufficiently

Fracture mechanism

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

 

 

Fracture of femur neck

• Geriatric population – simple fall

• Younger population – high energy injury

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

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

TreatmentOptions

– Non-operative• very limited role• Activity modification• Skeletal traction

– Operative• ORIF• Hemiarthroplasty• Total Hip Replacement

biological therapy

Management

Conservative: analgesia, bed rest, traction–if pt not willing to consent for surgery or if

not expected to survive surgery

Surgical: Manninger et al showed significant reduction in osteonecrosis and segmental collapse if performed within 6 hr–Head sparing: screws, DHS–Head sacrificing: hemi, THR

Young Patients

Non-displaced fractures• At risk for secondary displacement• Urgent ORIF recommended

Displaced fractures• Patients native femoral head best• AVN related to duration and degree of

displacement• Irreversible cell death after 6-12 hours• Emergent ORIF recommended

Elderly PatientsOperative vs. Non-operative

–Displaced fractures • Unacceptable rates of mortality, morbidity, and

poor outcome with non-operative treatment

–Non-displaced fractures • Unpredictable risk of secondary displacement

– AVN rate 2X

–Standard of care is operative for all femoral neck fractures• Non-operative tx may have developing role in

select patients with impacted/ non-displaced fractures

Acceptable Reduction

Lowell’s Alignment theory– outline of femoral head

& neck junction will have convex outline of femoral head meeting concave outline of femoral neck regardless on all views

– Image should produce an S or reverse S

– If image is a C fracture is not reduced

Garden Alignment Index

Treatment choices:

1: Cannulated Hip screws.

2: Dynamic Hip Screw.

3: Cephalo-medullary device.

4: Hemiarthroplasty Hip.

5: Total Hip Replacement.

operations

ORIF

Hemi

THR

Cannulated Screws

Cannulated Screws

Good Bad

Dynamic Hip Screw

Good for fracture with more vertical fracture line

Problem w this is that cannulated screw will prevent fracture impaction non union

Sacrifices large amount of boneAnti-rotation screw often needed

Hemi Vs. THR• Dislocation rates:

– Hemi 2-3% vs. THR 11% (short term)• 2.5% THR recurrent dislocation (Cabanela1999)

• Reoperation:– THR 4% vs. Hemi 6-18%

• DVT / PE / Mortality – No difference

• Pain / Function / Survivorship / Cost-effectiveness• THR better than Hemi (Iorio 2001)

Complications

Failure of Fixation• Inadequate / unstable reduction• Poor bone quality• Poor choice of implant

Treatment–Elderly: Arthroplasty–Young: Repeat ORIF

Valgus-producing osteotomy Arthroplasty

讲者简介

• 蔡友治 03 级浙大临床七年制• 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

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