Fractures of the Femoral Neck
Importance
- unsolved #
- affect the elderly – preceded by OP
- 250.000 hip #s in USA / yr
- increase as society more geriatric
- socio-economical burden
Anatomy
Intracapsular femoral neck / head
- #-healing different
- no cambium layer in its fibrous covering
- no peripheral callus formation –> healing endosteal union alone
Trabecular system (Ward)
- bone deposition along stress lines
- calcar femorale - dense bone that reinforces femoral neck postero-inferiorly
- trabeculae disappear with OP – Singh index (VI – I)
Blood supply special
- extracapsular arterial ring at base of femoral neck
- posteriorly large branch of MFCA (med. fem. circumflex)
- anteriorly by smaller branches of LFCA
- superior & inf. gluteal artery -> minor contributions
- ascending cervical branches - retinacular arteries
- pass under synovium on the neck
- risk of injury at #
- subsynovial intracapsular ring (Hunter)
- second ring at margin of cartilage
- lateral epiphyseal arteries as penetrate the head
- artery of ligamentum teres
- derived from obturator or MFCA
- medial epiphyseal arteries
- inadequate to supply femoral head with displaced #s
Epiphyseal Blood Supply
- lateral epiphyseal vessels (retinacular vessels) enter head postero-superiorly -> main blood supply
- medial epiphyseal vessels entering thru ligamentum teres -> supply area around fovea
- intraosseous cervical vessels from marrow
NOF
- intraosseous vessels disrupted -> nutrition of head depends on remaining retinacular vessels & vessels in lig.teres
- position at reduction NB in development of AVN
- valgus reduction -> kinking of lat.epiphyseal vessels & tethering of med.epiphyseal vessels in lig.teres
AVN following # NOF
- risk of AVN ~ degree of initial displacement of fracture
- minimally displaced # -> low risk < 10%
- displaced # -> AVN may be > 80%
- most retinacular vessels disrupted -> femoral head nutrition dependent on remaining retinacular vessels & vessels in ligamentum teres
Aseptic necrosis - AVN
- avascular segment early after #NOF, reduction, pinning
- revascularization occurs from
- remaining blood supply
- vascular ingrowth at #-site
X-ray - increased density from
- new bone laid down
- relative increase in density compare to OP around
- calcification in marrow (decreased blood wash out)
- early detection - MRI
Late segmental collapse
- if no repair of necrotic bone or process slow
- x-ray - flattening of head & # of subchondral bone (crescent sign)
Prevention
- position achieved at reduction NB
- valgus & rotatory malposition -> affect blood supply
- screws in superior or lateral position -> interrupt lateral epiphyseal vessels
- early fixation of # -> decrease risk of AVN
- hip joint capsulotomy/aspiration << AVN – controversial
Mechanism of injury
- fall producing a direct blow to GT
- lateral rotation of extremity
- major trauma in young patients
Classification
Anatomic location
- subcapital – beneath articular surface of head
- transcervical - # across neck between head & GT
- base of neck – extracapsular -> not included in NOF#
Pauwels classification
- based on # angle
- Type I – fracture line 30° from horizontal
- Type II - line 50°
- Type III - line > 70° from horizontal
- little difference between nonunion & AVN rates of type II & III #s -> not good prognosticator
Garden classification
- based on degree of displacement
- garden I-II & Garden III-IV treated similarly
Garden I
- incomplete or impacted fracture
- trabeculae of inferior neck still intact
- includes “abducted impaction fracture”
- AVN develops in 10-40% with or without internal fixation
- extreme valgus position -> kinking of vessels
- risk of non-union low
Garden II
- complete frx without displacement
- wt bearing trabeculae interrupted by #line across entire neck
- slight varus -> not impacted -> no bony stability -> displacement occur unless fixed internally
- risk of non-union
- transverse #line heal well
- vertical configuration -> >> nonunion rate
Rx (Garden I & II)
- closed reduction & IF with cannulated screws or pins - emergency
Garden III
- complete fracture with partial displacement
- if it needs a reduction, then its a type III fracture
- femoral & acetabular trabeculae do not align
- retinacular vessels of Weitbrecht remain attached
- risk of non union - >> with vertical #line
Garden IV
- complete fracture with total displacement
- no continuity between proximal and distal fragments
- trabeculae in head line up with acetabular lines
Rx (Garden III & IV)
- cannulated screws in young
- hemiarthroplasty or THR
Signs & Symptoms
Stress & impacted
- Hx of fall
- pain in groin or along medial side of knee
- tenderness over GT
- fair ROM (active – passive)
- may be able to walk
X-rays
- normal initially
- tomograms may help
- bone scan –> uptake after 72 hrs (slow turnover d/t OP)
- MRI – prompt
Displaced
- pain in hip region
- leg in ER, abD & shortened -> traction for pain relief & protect remaining vascular supply
X-ray
- confirms
- true AP & lateral
Radiology of the Hip
AP view
- with foot IR 15° - best views of femoral neck
Lateral view
- patient supine & opposite hip flexed & abD
- shows posterior comminution
Frogleg Lateral View
- do not order in any pt.suspected hip # or dislocation
- patient supine with knees flexed, soles together & thighs abducted
- central beam directed vertically just above symphysis
Radiographic Features
- femoral head & neck produces an S or reversed S curve outline on all projections used to assess reduction
- posterior comminution - most evident on lateral view
- higher prevalence of non-union
Non-displaced
- if plain radiographs N -> MRI- immediate interpretation
- bone scan after 48-72 hrs
- pubic ramus # common - tenderness over symphysis
Garden’s Alignment Index
- angle of compression trabeculae on AP & lateral view
- should be 160° on AP
- 180° on lateral
- to assess reduction
- acceptable reduction within range of 155-180° on both views -> minimizes non-union and AVN
Lowell’s Alignment Theory
- radiographic outline of femoral head & neck junction have a convex outline -> S or reversed S curve
- if outline reveals an unbroken C curve -> # not reduced
Differential Diagnosis
- with hip pain and no apparent
Pubic ramus fracture
- commonly seen in the elderly
- tenderness over the pubic bone
Treatment
Impacted or incomplete fractures – Garden I
- valgus & abD position
- femoral neck cortex impacted into cancellous head -> stability
Non-operative Rx
- spica cast -> risk of disimpaction
- only if # several weeks old & pt.walks without pain
- immobilisation -> fatal pulmonary complications
Operative
- do not disimpact #
- internal fixation with multiple pins
- Knowles pins, cannulated screws, Muller screws
- larger implants (as compression hip screws) may disimpact #
Complete undisplaced – Garden II
- no impaction – likely to displace if not fixed
Non-operative
Operative
- closed reduction & internal fixation
- multiple screws (cannulated, Muller)
- DHS + screw above to prevent rotation
Displaced Fractures – Garden III / IV
Non-operative Rx
- historical
- high rate of deformity, non-union
Operative
- goal – anatomical reduction & stable fixation
- as an emergency in younger patients
- << AVN if # reduced w/in 12 hrs
- skin traction while preparing pt.-> >> blood flow!
- quick resuscitation if necessary (rehydration, basic bloods etc.)
Closed reduction
- on fracture table
- in extension – traction, then IR & abD (Whitman)
- in flexion – hip flexed to 90°, traction in line of femur, IR, then abD & bring down to extension
(Leadbetter)
- assessed with image or x-rays
- garden’s alignement index
- lowell’s alignement curves
- assess infero-medial apposition – calcar line
- assess posterior comminution – risk of loss of reduction later
- acceptable reduction
- neck-shaft angle between 130-150°
- valgus reduction - increase stability
- excessive valgus(>185°) >> rate of AVN (tethering vessels)
- can be reduced by decreasing traction
- varus reduction
- increased non-union rate
- more traction applied, & GT pushed medially
- angulation (anteversion)
- should be between 0-15° of anteversion
- stability of reduction
- evaluate posterior comminution on lateral view
- risk of loss of reduction & non-union
- gentle manipulation max. 2-3x
- if no success -> open reduction or hemiarthroplasty
Open reduction
- if closed reduction unacceptable -> >> risk of AVN or non-union
- difficult procedure
- anterior or anterolateral approach (Watson-Jones, Hardinge’s)
- use posterior approach for pedicle bone grafting
Methods of fixation
Goals
- anatomical reduction
- closed or open if necessary
- open reduction thru’ Watson-Jones approach
- may be difficult on traction table
- rigid fixation & impaction at site
- proper placement of fixation device
Multiple pins & screws
- Knowles pins, Muller screws, cannulated screws etc.
- can be performed under local
- ideal in impacted #s
- 3 or 4 pins inserted parallel
- do not penetrate head
Fixed-angle nails
- Smith-Petersen nail, Jewett nail
- Historical
Sliding compression screw
- Richards screw, DHS
- improved fixation strength
- if danger of rotating head -> accessory pin above screw
Pin placement
- inferior on AP view
- slightly posterior or central on lateral view
- depth - tip within 1cm from subchondral bone
- ideally 135° angle to femoral shaft
Postoperative treatment
- if stable fixation - PWB with walker on D2 for 6-8/52
- gradually FWB as callus formation allows
- if unstable # or unco-operative pt.-> mobilize in bed & sitting
- follow up with serial x-rays until union
- check for possible AVN also
Hemiarthroplasty
Indications
- physiologic age > 75 yrs – life expectancy < 5 yrs
- poor general health would prevent a second operation
- pathologic hip fractures
- Parkinson’s dx, hemiplegia, or other neurological dx
- severe OP with loss of primary trabeclae in femoral head
- inadequate closed reduction in old pt.
- displaced (Garden 3 & 4)
- pre-existing hip dx (DJD, RA, AVN)-> THR rather
Contraindications
- pre-existing sepsis
- young patient (< 75 yr) -> THR
- preexisting dx of the acetabulum -> THR
Advantage
- allows immediate weight bearing – cemented
- eliminates AVN or non-union -> no need for second op
Austin Moore Prosthesis
- only true calcar support prosthesis
- if 1/2 to 3/4 inches of remaining femoral neck above LT
- fenestration in stem ->“self locking” & bony ingrowth
- new design -> solid-stem - interference fit
- surgery shorter – no cementing
Thompson Prosthesis
- for pts with limited femoral neck above LT
- if poor bone stock
- cemented
- can be modular
- should be used rather than A-M
Pre Op Planning
- correctly size prosthesis for the femoral head
- if too large - tight joint with decreased motion & pain
- if too small - erosion, superomedial migration & pain
- neck length also critical
- ideally inserted prostheses should restore anatomical distance between superior aspect of LT & acetabulum -> restore length of abductor mechanism
- inserted into medullary canal in neutral or slight valgus position
Surgical Approaches
- Anterolateral Approach - Watson Jones
- Lateral Approach – Hardinge
- Posterior Approach
Complications
Mortality
- pts. older & more debilitated - 10 to 40%
- small difference from pts. with ORIF
Fracture of femur
- 4.5%
- when surgeon attempts to reduce prosthesis
- consider cement combined with a long stem prosthesis
Dislocation
- less than 10%
- avoid dislocation during bed to bed transfers
- more common with too much anteversion or retroversion
- use abduction pillow
Sepsis
- 2% to 20%
- more common with posterior surgical approach
- may be superficial or deep, acute, subacute or chronic
Pain (loosening or subsidence)
- main late complication
- usually from loosening or migration of prosthesis
- presence of a radiolucent zone around prosthesis
- if clinical signs & symptoms -> revision to THR
- less with cemented prosthesis
Bipolar prosthesis
- femoral stem + double jointed head component ->> acetabular friction
- cost factor
Total hip arthroplasty
Indications
- pre-existing hip dx. – OA, RA, Paget’s, pathological etc.
- active, mobile elderly pt. with displaced #NOF
- failure after ORIF of #NOF
- if hemiarthroplasty indicated, but have dx. of contralateral hip
Results
- inferior to THR in OA & RA
Stress Fractures of Femoral Neck
- relatively uncommon injuries - military recruits & athletes
- normal bone undergoing repeated submaximal stresses or diseased bone undergoing repeated minimal stresses
- classified as either tension or compression
Radiographs
- initial radiographs often normal
- bone scan or MRI
Non-surgical Treatment
- serial radiographs to detect changes in pattern or displacement
- compression occur on the inferior aspect of NOF -> more stable & can be treated without surgery
- initially with bed rest followed by protected wt bearing
Surgical Treatment
- fractures of both cortices -> immediate internal fixation - cannulated screws
Pathologic Hip Fractures
Hyperparathyroidism
- incidence of hip frx is about 10%
- in younger pts with good bone stock - ORIF
- in elderly pts consider primary THR
- renal failure -> high risk of infection
Metastatic Dx
- common – 30-50% around hip
- consider cemented solid stem hemiarthroplasty or THR
- X-Ray - acetabulum & distal femoral shaft involvement
Pagets disease
- NOF << intertrochanteric or subtrochanteric
- non displaced fractures - ORIF
- often do not heal during sclerotic phase
- heal rapidly during the vascular phase
- possibility of excessive bleeding
- displaced fractures -> prosthetic replacement
- x-ray of femoral shaft to determine excessive bowing
Parkinson’s Disease
- 6 month mortality of 60%
- osteoporosis & contractures
- consider primary prosthetic replacement (hemi or THR)
- depends on age, activity, life expectancy
Spastic Hemiplegia/Stroke
- up to 10% have #NOF
- usually on hemiplegic side -> varying degrees of flexion & adduction contracture associated with spasticity
- if ORIF planned -> tenotomy before reduction
- if marked spastic hemiplegia -> hemiarthroplasty
- also consider tenotomy of hip contractures
Complications
Mortality
- 10-40%
- highest in 1st 6 months
- higher in pts.from nursing homes
Thrombo-embolic dx
- leading cause of death
- incidence of DVT ~40% after hip surgery
Prophylaxis
- dextran
- aspirin
- low-dose warfarin
- heparin
- low-molecular-weight heparin
Infection
- 1%
- superficial or deep
- acute, subacute or chronic
Prophylaxis
- iv. AB – Kefzol 1g 8hrly 3 doses
- aseptic technique
Non-union
- improved fixation devices -> < 5%
- pain in groin or buttock
- some varus angulation
- if no evidence of healing by 6-12 months after
- comminution, especially posterior -> >> risk
- posterior muscle pedicle graft (quadratus femoris) enhance # stability & union, >> blood supply femoral head
Rx
- determine viability of femoral head, degree of OP & neck resorption
Salvage femoral head
- refixation with BG & valgus OT
- << sharing force at site
- produce valgus -> shortens lever arm of abDs from GT to femoral head-> >> P°, AVN & early OA of head
- use cane after OT
- McMurray displacement OT
- Schanz angulation OT
- arthrodesis
Arthroplasty (hemi- or THR) if head collapsed
Avascular necrosis
- major long term complication
- early anatomical reduction & stable fixation may prevent
- presents ~ 6 months on X-ray
- MRI – early detection
- disturbed by metallic implants
Rx
- symptomatic - core decompression, osteotomies
- arthroplasty