SUMMARY

• Femoral head fractures are rare traumatic injuries that are usually associated with hip dislocations.

• Diagnosis can be made by pelvis/hip radiographs but frequently require CT scan for surgical planning. 

• Treatment may be nonoperative or operative depending on the location of the fracture and degree of fracture displacement.

EPIDEMIOLOGY

• Incidence

  • rare

    • seen in 12% of patients with hip dislocations

      • increased incidence due to higher MVAs and better resuscitation

ETIOLOGY

• Pathophysiology

  • mechanism of injury

    • impaction, avulsion or shear forces involved

      • unrestrained passenger MVA (knee against dashboard)

      • falls from height

      • sports injury

      • industrial accidents

  • pathoanatomy

    • the location and size of the fracture fragment and degree of comminution depend on the position of the hip at the time of dislocation 

      • 5-15% of posterior hip dislocations are associated with a femoral head fracture because of contact between femoral head and posterior rim of acetabulum

      • anterior hip dislocations are associated with impaction/indentation fractures of the femoral head

• Associated conditions

  • femoral neck fracture (see Pipkin Classification below)

  • acetabular fracture (see Pipkin Classification below)

  • sciatic nerve neuropraxia

  • femoral head AVN

  • ipsilateral knee ligamentous instability (knee vs dashboard)

ANATOMY

• Blood supply

  • medial femoral circumflex artery (MFCA) 

    • main blood supply to the weightbearing portion of the femoral head

    • MFCA originates from the profunda femoris

  • artery to the ligamentum teres

    • lesser blood supply (10-15%)

    • from the obturator artery or MFCA

    • supplies perifoveal area

CLASSIFICATION

• Pipkin Classification
  Type I	Fracture below fovea/ ligamentum (small) Does not involve the weight-bearing portion of the femoral head
  Type II	Fracture above fovea/ ligamentum (larger) Involves the weight-bearing portion of the femoral head
  Type III	Type I or II with an associated femoral neck fracture High incidence of AVN
  Type IV	Type I or II with associated acetabular fx (usually posterior wall fracture)

PRESENTATION

• History

  • frontal impact MVA with knee striking dashboard

  • fall from height

• Symptoms

  • localized hip pain

  • unable to bear weight

  • other symptoms associated with impact

• Physical exam

  • inspection

    • shortened lower limb

      • with large acetabular wall fractures, little to no rotational asymmetry is seen

    • posterior dislocation

      • limb is flexed, adducted, internally rotated

    • anterior dislocation

      • limb is flexed, abducted, externally rotated

    • ipsilateral knee

      • ligamentous stability

  • neurovascular

    • may have signs of sciatic nerve injury

IMAGING

• Radiographs

  • recommended views

    • AP pelvis, hip series

      • both pre-reduction and post-reduction

    • judet views

      • associated acetabular fracture

    • inlet and outlet views

      • associated pelvic ring injury

• CT scan

  • indications

    • post reduction to evalute for loose bodies and presence/size of fracture fragments

  • findings

    • femoral head fracture (size, location, comminution)

    • plane of femoral head fracture

    • intra-articular fragments

    • posterior pelvic ring injury

    • impaction

    • acetabular fracture

TREATMENT

• Nonoperative

  • hip reduction

    • indications

      • acute dislocations

        • reduce hip dislocation within 6 hours

    • outcomes

      • 5-40% incidence of femoral head osteonecrosis

      • increased risk with increased time to reduction

  • TDWB x 4-6 weeks, restrict adduction and internal rotation

    • indications

      • Pipkin I 

         

      • nondisplaced Pipkin II with < 1 mm step off

      • no interposed fragments

      • stable hip joint

    • outcomes

      • satisfactory results if <1mm step off

        • serial radiographs required

      • development of post-traumatic arthritis based on joint incongruity and initial cartilage damage

• Operative

  • ORIF

    • indications

      • Pipkin II with > 1 mm step off

      • if performing removal of loose bodies in the joint

      • associated neck or acetabular fx (Pipkin type III and IV)

      • polytrauma

      • irreducible fracture-dislocation

      • Pipkin IV

        • treatment dictated by characteristics of acetabular fracture

        • small posterior wall fragments can be treated nonsurgically and suprafoveal fractures can then be treated through an anterior approach

    • outcomes

      • outcomes mimic those of their associated injuries (hip dislocations and femoral neck fractures)

        • high rate of AVN and catastrophic failure following ORIF of Pipkin III injuries  

           

      • poorer outcomes associated with

        • use of posterior (Kocher-Langenbeck) approach

        • use of 3.0mm cannulated screws with washers

  • arthroplasty

    • indications

      • Pipkin I, II (displaced), III, and IV in older patients

      • fractures that are significantly displaced, osteoporotic or comminuted

    • outcomes

      • best resereved for older patients

      • higher dislocation risk than THA performed for OA

  • arthroscopy

    • indications

      • removal of loose bodies

    • outcomes

      • dependent on ability to remove incarcerated fragments and initial cartilage damage

TECHNIQUES

• hip reduction

  • technique

    • adequate sedation and muscular relaxation are vital

    • traction in-line with the thigh, extremity slightly adducted, counterforce on pelvis

    • forceful reduction should be avoided

    • obtain post reduction CT

• TDWB x 4-6 weeks, restrict adduction and internal rotation

  • technique

    • perform serial radiographs to document maintained reduction

• ORIF of femoral head (Pipkin I, II, III)

  • approach

    • anterior (Smith-Peterson) approach 

        

      • utilizes internervous plane between the superior gluteal and femoral nerves

      • improved visualization

      • reduced surgical time

      • improved fracture reduction

        • femoral head fracture is commonly anteromedial

      • lower incidence of AVN

      • less blood loss

      • higher rate of functionally significant HO compared to posterior approach

    • anterolateral (Watson-Jones) 

      • utilizes intermuscular plane between the tensor fascia lata and gluteus medius (both superior gluteal nerve)

    • surgical hip dislocation with trochanteric flip osteotomy 

       

      • allows for complete exposure of femoral head and acetabulum

      • similar functional outcomes to other approaches

      • higher rates of HO compared to non-osteotomy-based approaches

      • lower rates of subsequent AVN and post-traumatic osteoarthritis compared to alternative approaches

  • exposure

    • periacetabular capsulotomy to preserve blood supply to femoral head

  • fixation

    • two or more 2.7mm or 3.5mm lag screws 

       

      • countersink the heads of the screws to avoid screw head prominence

    • headless compression screws

    • bioabsorbable screws

  • postop

    • rehabilitation

      • mobilization

        • immediate early range of motion

      • weightbearing

        • delay weight bearing for 6-8 weeks

      • stress strengthening of the quadriceps and abductors

    • radiographs

      • radiographs after 6 months to evaluate for AVN and osteoarthritis

• ORIF of femoral head and acetabulum (Pipkin IV)

  • approach

    • posterior (Kocher-Langenbeck) approach with digastric osteotomy 

        

      • trochanteric osteotomy allows access to both the femoral head fracture and posterior wall acetabular fracture

      • preserves the medial circumflex artery supply to the femoral head

      • utilizes plane created by splitting of gluteus maximus (no true internervous plane)

    • anterior (Smith-Peterson) approach

      • for fixation of suprafoveal fractures

        • small posterior wall fractures may not need to be addressed surgically

• Arthroplasty

  • approach

    • can use any hip approach for arthroplasty

      • posterior (Kocher-Langenbeck) approach provides the best visualization of acetabular posterior wall fracture

  • pros & cons

    • allows immediate postoperative mobilization and weightbearing

    • hemiarthroplasty can be utilized if no acetabular fracture present

COMPLICATIONS

• Heterotopic ossification 

  • overall incidence is 6-64%

    • anterior approach has increased heterotopic ossification compared with posterior approach

  • treatment

    • administer radiation therapy if there is concern for HO

      • especially if there is an associated head injury

• AVN

  • incidence is 0-23%

    • risk is greater with delayed reduction of dislocated hip

    • anterior approach not associated with increased AVN risk

• Sciatic nerve neuropraxia

  • incidence is 10-23%

    • usually peroneal division of sciatic nerve

    • spontaneous recovery of function in 60-70%

• DJD

  • incidence 8-75%

  • due to joint incongruity or initial cartilage damage

• Decreased internal rotation

  • may not be clinically problematic or cause disability