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

• historical

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
• if posterior comminution

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
• RA, OA or Parkinson’s dx

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
• 40 mg Clexane sc. daily

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
• Tc scan, SPECT scan

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