femoral neck fracture

Question 1

Epidemiology

Answer 1

• increasingly common due to aging population
• women > men
• whites > blacks
• United states has highest incidence of hip fx rates worldwide
• most expensive fracture to treat on per-person basis

Question 2

Mechanism

Answer 2

• high energy in young patients
• low energy falls in older patients

Question 3

Associated injuries

Answer 3

femoral shaft fractures

• 6-9% associated with femoral neck fractures
• treat femoral neck first followed by shaft

Question 4

mortality

Answer 4

mortality

• ~25-30% at one year (higher than vertebral compression fractures)

Question 5

predictors of mortality

Answer 5

• pre-injury mobility is the most significant determinant for post-operative survival
• in patients with chronic renal failure, rates of mortality at 2 years postoperatively, are close to 45%

Question 6

Blood supply to femoral head

Answer 6

• major contributor is medial femoral circumflex (lateral epiphyseal artery)
• some contribution to anterior and inferior head from lateral femoral circumflex
• some contribution from inferior gluteal artery
• small and insignificant supply from artery of ligamentum teres
• displacement of femoral neck fracture will disrupt the blood supply and cause an intracapsular hematoma (effect is controversial)

Question 7

Classification

Answer 7

Question 8

Imaging

Answer 8

• Radiographs
  
  • Recommended views
    
    • AP
      
      • traction-internal rotation AP hip is best for defining fracture type
    • cross-table lateral
    • full-length femur
  • Optional views
    
    • consider obtaining dedicated imaging of uninjured hip to use as template intraop
• CT
  
  • helpful in determining displacement and degree of comminution in some patients
• MRI
  
  • helpful to rule out occult fracture
  • not helpful in reliably assessing viability of femoral head after fracture
• Bone scan
  
  • helpful to rule out occult fracture
  • not helpful in reliably assessing viability of femoral head after fracture
• Duplex Scanning
  
  • indication
    
    • rule out DVT if delayed presentation to hospital after hip fracture

Question 9

How would you correlate the proximal femur bone qulity with osteoprosis and risk of fracture?

Question 10

Trabecular types in proximal femur

Answer 10

Five trabecular types can be present in the proximal part of the femur:

1. principal compression group
2. secondary compression group
3. primary tensile group
4. secondary tensile group
5. Greater trochanteric group

Question 11

The Five Major Groups of Trabeculae in details?

Answer 11

1. Principal Compressive Group
   
   • Extend from medial cortex of femoral neck to superior part of femoral head
   • Major weight-bearing trabeculae
   • In normal femur are the thickest and most densely packed
   • Appear accentuated in osteoporosis
   • Last to be obliterated
2. Secondary Compressive Group
   
   • Originate at the cortex, near the lesser trochanter
   • Curve upward and laterally toward the greater trochanter and upper femoral neck
   • Characteristically thin and widely separated
3. Principal Tensile Group
   
   • Originate from the lateral cortex, inferior to the greater trochanter
   • Extend in an arch-like configuration medially, terminating in the inferior portion of the femoral head
4. Secondary Tensile Group
   
   • Arise from the lateral cortex below the principal tensile group
   • Extend superiorly and medially to terminate after crossing the middle of the femoral neck
5. Greater Trochanter Group
   
   • Composed of slender and poorly defined tensile trabeculae
   • Arise laterally below the greater trochanter
   • Extend upward to terminate near the greater trochanter’s superior surface

Question 12

Singh index—radiologic grades.

Answer 12

Singh has shown that trabecular loss occurs in a predictable sequence that can be used to grade the severity of osteopenia. He recognized that the compressive trabeculae were more essential than the tensile trabeculae and that the peripherally located trabeculae were more vital than central ones.

Question 13

Displaced intracapsular neck of femur fractures:
dislocation rate after total hip arthroplasty

Question 14

Nonoperative

Answer 14

observation alone

• indications
  
  • may be considered in some patients who are non-ambulators, have minimal pain, and who are at high risk for surgical intervention

Question 15

Operative

Answer 15

1. ORIF
2. cannulated screw fixation
3. sliding hip screw
4. hemiarthroplasty
5. total hip arthoplasty

Question 16

what is the indications for ORIF

Answer 16

indications

• displaced fractures in young or physiologically young patients
  
  • ORIF indicated for most pts <65 years of age

Question 17

cannulated screw fixation indecations

Answer 17

• nondisplaced transcervical fx
• Garden I or II in the physiologically ACTIVE elderly and no osteoarthretic changes
• displaced transcervical fx in young patient
  
  • considered a surgical emergency
  • achieve reduction to limit vascular insult
  • reduction must be anatomic, so open if necessary

Question 18

sliding hip screw indecations

Answer 18

• basicervical fracture
• vertical fracture pattern in a young patient
  
  • biomechanically superior to cannulated screws (may not be clinically superior)
• consider placement of additional cannulated screw above sliding hip screw to prevent rotation

Question 19

hemiarthroplasty ind

Answer 19

1. controversial
2. debilitated elderly patients
3. metabolic bone disease

Question 20

total hip arthoplasty indications

Answer 20

• controversial
• older active patients
• patients with preexisting hip osteoarthritis
  
  • more predictable pain relief and better functional outcome than hemiarthroplasty
• Garden III or IV in patient < 85 years

Question 21

General Surgical Consideration

Answer 21

1. time to surgery
2. treatment approach based
3. fixation with implants that allow sliding
4. open versus closed reduction

Question 22

time to surgery

Answer 22

time to surgery

• controversial
  
  • reduction method and quality has more pronounced effect on healing than surgical timing
• elderly patients with hip fractures should be brought to surgery as soon as medically optimal
  
  • the benefits of early mobilization cannot be overemphasized

Question 23

treatment approach based on

Answer 23

• degree of displacement
• physiologic age of the patient (young is < than 50
• ipsilateral femoral neck and shaft fractures
  
  • priority goes to fixing femoral neck because anatomic reduction is necessary to avoid complications of AVN and nonunion

Question 24

fixation with implants that allow sliding

Answer 24

• permit dynamic compression at fx site during axial loading
• can cause shortening of femoral neck
  
  • prominent implants
  • affects biomechanics of hip joint
  • lower physical function on SF-36
  • decreased quality of life
• anatomic reduction with intraop compression and placement of length stable devices decrease shortening

Question 25

open versus closed reduction

Answer 25

• worse outcomes with displacement > 5 mm (higher rate of osteonecrosis and nonunions)
• no consensus on which reduction approach is superior
• multiple closed reduction attempts are associated with higher risk of osteonecrosis of the femoral head

Question 26

what are the OPERATIVE approach in FN#

Answer 26

1. limited anterior Smith-Peterson
2. Watson-Jones

Question 27

limited anterior Smith-Peterson

Answer 27

• 10cm skin incision made beginning just distal to AIIS
• incise deep fascia
• develop interval between sartorious and TFL
• external rotation of thigh accentuates dissection plane
• LFCN is identified and retracted medially with sartorius
• identify tendinous portion of rectus femoris, elevate off hip capsule
• open capsule to identify femoral neck

Question 28

Watson-Jones

Answer 28

• used to gain improved exposure of lower femoral neck fractures
• skin incision approx 2cm posterior and distal to ASIS, down toward tip of greater trochanter
• incision curved distally and extended 10cm along anterior portion of femur
• incise deep fascia
• develop interval between TFL and gluteus medius
• anterior aspect of gluteus medius and minimus is retracted posteriorly to visualize anterior hip capsule
• capsule sharply incised with Z-shape incision
• capsulotomy must remain anterior to lesser trochanter at all times to avoid injury to medial femoral circumflex artery

Question 29

reduction (method may vary)

Answer 29

• evacuate hematoma
• place A to P k-wires into femoral neck/head proximal to fracture to use as joysticks for reduction
• insert starting k-wire (for either cannulated screw or sliding hip screw) into appropriate position laterally, up to but not across the fracture
• once reduction obtained, drive starting k-wire across fracture
• insert second threaded tipped k-wire if adding additional fixation
• Leadbetter meatouver

Question 30

Cannulated Screw Fixation technique

Answer 30

• three screws if noncomminuted (3 screw inverted triangle shown to be superior to two screws)
• order of screw placement (this varies)
  
  • 1-inferior screw along calcar
  • 2-posterior/superior screw
  • 3-anterior/superior screw
• obtain as much screw spread as possible in femoral neck
• inverted triangle along the calcar (not central in the neck) has stronger fixation and higher load to failure
• four screws considered for posterior comminution
  
  • clear advantage of additional screws not proven in literature
• starting point at or above level of lesser trochanter to avoid fracture
• avoid multiple cortical perforations during guide pin or screw placement to avoid development of lateral stress riser

Question 31

Hemiarthroplasty

Answer 31

• approach
  
  • posterior approach has increased risk of dislocations
  • anterolateral approach has increased abductor weakness
• technique
  
  • cemented superior to uncemented
  • unipolar vs. bipolar

Question 32

Total Hip Replacement

Answer 32

• technique
  
  • should consider using the anterolateral approach and selective use of larger heads in the setting of a femoral neck fracture
• advantages
  
  • improved functional hip scores and lower re-operation rates compared to hemiarthroplasty
• complications
  
  • higher rate of dislocation with THA (~ 10%)
    
    • about five times higher than hemiarthroplasty

Question 33

Complications

Answer 33

1. Osteonecrosis
2. Nonunion
3. Dislocation

Question 34

Osteonecrosis

Answer 34

• incidence of 10-45%
• recent studies fail to demonstrate association between time to fracture reduction and subsequent AVN
• increased risk with
  
  • increase initial displacement
    
    • AVN can still develop in nondisplaced injuries
  • nonanatomical reduction
• treatment
  
  • major symptoms not always present when AVN develops
  • young patient
    
    • > 50% involvement then treat with FVFG vs THA
  • older patient
    
    • prosthetic replacement (hemiarthroplasty vs THA)

Question 35

Nonunion

Answer 35

• incidence of 5 to 30%
  
  • increased incidence in displaced fractures
  • no correlation between age, gender, and rate of nonunion
• varus malreduction most closely correlates with failure of fixation after reduction and cannulated screw fixation.
• treatment
  
  • valgus intertrochanteric osteotomy
    
    • indicated in patients after femoral neck nonunion
      
      • can be done even in presence of AVN, as long as not severely collapsed
      • turns vertical fx line into horizontal fx line and decreases shear forces across fx line
  • free vascularized fibula graft (FVFG)
    
    • indicated in young patients with a nonviable femoral head
  • arthroplasty
    
    • indicated in older patients or when the femoral head is not viable
    • also an option in younger patient with a nonviable femoral head as opposed to FVFG
  • revision ORIF

Question 36

Failure rates

Answer 36

• high early failure rates in fixation group, which stabilizes after 2 years
  
  • 2-year follow-up (elderly population >70 years) with displaced femoral neck fractures
    
    • 46% with fixation techniques
    • 8% with arthroplasty techniques
  • 2-to-10 year follow-up
    
    • failure rate approx. 2-4%, respectively
• overall failure rates still higher in fixation vs. arthoplasty at 10-year follow-up
• sliding hip screw with lower reopeation rates compared to cannulated screws:
  
  • displaced femoral neck fractures
  • basicervical femoral neck fractures
  • current smokers

Question 37

THA postop dislocation rate in letrature

Answer 37

Dislocation is one of the most common orthopaedic complications after primary total hip arthroplasty (THA).

The reported dislocation rate in elective THR is 5–8%. This number increases up to 22% for THA done for neck of femur (NOF)

fractures. Larger femoral head sizes increase the head–neck ratio and range of motion before impingement, therefore reducing

the dislocation rate

However a recent study from Cape town SA SHOWS

outcomes of THA in patients with NOF fractures can be favourable and provide good long-term prosthesis
survival. We report on low dislocation rate post total hip replacement for intra-capsular NOF fractures.

Question 38

Prospective randomized clinical trial comparing hemiarthroplasty to total hip arthroplasty in the treatment of displaced femoral neck fractures

Answer 38

At 24 months, THA patients had significantly less pain on the SF-36 subscale than hemiarthroplasty patients

scored significantly better on the SF-36 mental health subscale

Total hip arthroplasty patients also had superior WOMAC function scores

Significant differences in outcomes, without a significantly greater incidence of complications, suggest THA is a valuable treatment option for the active elderly hip fracture population.

Question 39

Outcomes of total hip arthroplasty are similar for patients with displaced femoral neck fractures and osteoarthritis

by Abboud

Answer 39

• This is a retrospective study of 60 patients who had total hip arthroplasties between 1997 and 2001.
• 30 patients had total hip arthroplasties for displaced femoral neck fractures
• 30 patients were treated with total hip arthroplasties for osteoarthritis.
• This study suggests that the outcomes for total hip arthroplasties in this consecutive series of patients treated for displaced femoral neck fractures and osteoarthritis are comparable

Question 40

more in recent letrature

Answer 40

Primary total hip replacement (THR) is suggested for treatment
of displaced neck of femur (NOF) fractures in patients with preexisting
arthrosis of the hip or if they expect a high level of
activity. Dislocation is one of the most common orthopaedic
complications after primary total hip arthroplasty (THA).1
Dislocation is associated with high morbidity and increased cost
for the patient. Dislocated THRs have worse outcomes
compared to THRs that do not dislocate. The two-year survival
rate for the dislocated THR is slightly over 50%.2
Improved surgical techniques and the evolution of implant
design have lowered the dislocation rate after hip arthroplasty
surgery for treatment of fractured NOF to approximately 1–5%.