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http://upload.orthobullets.com/topic/1036/images/pipkin 1.jpg
http://upload.orthobullets.com/topic/1036/images/hip position.jpg
http://upload.orthobullets.com/topic/1036/images/blood supply.jpg
http://upload.orthobullets.com/topic/1036/images/pipkin 2 4.jpg
Introduction
  • A rare fracture pattern that is usually associated with hip dislocations
    • the location and size of the fracture fragment and degree of comminution depend on the position of the hip at the time of dislocation  
  • Epidemiology
    • incidence
      • rare
      • increasing because of more MVA and better resuscitation
  • Mechanism
    • impaction, avulsion or shear forces involved
      • unrestrained passenger MVA (knee against dashboard)
      • falls from height
      • sports injury
      • industrial accidents
    • 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 usually 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
    • the femoral head has 3 sources of arterial supply  
      • extracapsular arterial ring
        • medial circumflex femoral artery (main supply to the head)
          • from profunda femoris
        • lateral circumflex femoral artery
      • ascending cervical branches
      • artery to the ligamentum teres
        • from the obturator artery or MCFA
        • supplies perifoveal area
Classification
 
Pipkin Classification
Type I
Fx below fovea/ligamentum (small)
Does not involve the weightbearing portion of the femoral head
  
Type II Fx above fovea/ ligamentum (larger)
Involves the weightbearing portion of the femoral head 
   
Type III Type I or II with associated femoral neck fx
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
    • neurovascular
      • may have signs of sciatic nerve injury
Imaging
  • Radiographs
    • recommended views
      • AP pelvis, lateral hip and Judet views
        • both pre-reduction and post-reduction
      • inlet and outlet views
        • if acetabular or pelvic ring injury suspected
  • CT scan
    • indications
      • after reduction
      • to evaluate:
        • concentric reduction
        • loose bodies in the joint
        • acetabular fracture
        • femoral head or neck fracture
    • findings
      • 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
      • technique
        • obtain post reduction CT
    • TDWB x 4-6 weeks, restrict adduction and internal rotation
      • indications
        • Pipkin I
        • undisplaced Pipkin II with < 1mm step off
        • no interposed fragments
        • stable hip joint
      • technique
        • perform serial radiographs to document maintained reduction
  • Operative
    • ORIF
      • indications
        • Pipkin II with > 1mm 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)
        • 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
Surgical Techniques
  • ORIF of femoral head (Pipkin I, II, III)
    • approach
      • anterior (Smith-Peterson) approach 
        • the anterior (Smith-Peterson) and anterolateral (Watson-Jones) approaches provide the best visualization of the head compared with the posterior approach
        • utilizes internervous plane between the superior gluteal and femoral nerves
        • no increased risk of AVN
        • shorter surgical time 
        • less blood loss 
        • ease of reduction and fixation
          • because femoral head fragment is commonly anteromedial
        • can use surgical hip dislocation if needed
      • anterolateral (Watson-Jones) 
        • utilizes intermuscular plane between the tensor fascia lata and gluteus medius (both superior gluteal nerve)
    • 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 
        • provides the best visualization of femoral head fracture and acetabular posterior wall fracture
        • preserves the medial circumflex artery supply to the femoral head
        • utilizes plane created by splitting of gluteus maximus (no true internervous plane
        • gluteus maximus is not denervated because it receives nerve supply well medial to the split
      • anterior (Smith-Peterson) approach
        • for fixation of suprafoveal fractures (if posterior wall fragments are small, they can be treated nonsurgically)
  • 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
      • total hip arthroplasty favored if patient physiologically younger or if 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 associated head injury
  • AVN
    • incidence is 0-23%
      • risk is greater with delayed reduction of dislocated hip
      • the impact of anterior incision on AVN is unknown
  • 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
 

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Questions (1)

(OBQ11.123) Assuming the images represent isolated injuries, which of the following Figures demonstrates a Pipkin II femoral head fracture? Review Topic

QID:3546
FIGURES:
1

Figure A

4%

(60/1512)

2

Figure B

21%

(323/1512)

3

Figure C

17%

(258/1512)

4

Figure D

56%

(852/1512)

5

Figure E

1%

(15/1512)

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

Figure D represents a Pipkin II femoral head fracture, which is defined as a fracture which is superior to the fovea. Differentiation between Pipkin I and Pipkin II fractures can be important, as suprafoveal injuries often require surgical fixation. Illustration A demonstrates the Pipkin fracture types.

Droll et al review femoral head fracture evaluation and treatment. They discuss non-operative indications (typically reserved for Pipkin I injuries) which include an anatomic or near anatomic reduction (<2 mm) of the femoral head fragment, a stable hip, and no interposed fragments preventing a congruent hip joint. They also state that an anterior surgical approach is preferred for fixation of Pipkin II type injuries.

Pipkin discusses the evaluation and treatment of hip fracture dislocations as defined by the Stewart and Milford classification scheme. He focuses on Grade IV injuries, which at the time lacked an appropriate treatment algorithm.

Incorrect Answers:
1,2-Figures A and B show Pipkin IV fractures, due to the presence of an associated acetabular fracture.
3-Figure C shows a Pipkin I fracture, as the fracture is infra-foveal
5-Figure E shows an example of a Pipkin III injury due to the presence of an associated femoral neck fracture.

ILLUSTRATIONS:

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