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http://upload.orthobullets.com/topic/1041/images/Xray - Lat - Hoffa fragment_moved.jpg
http://upload.orthobullets.com/topic/1041/images/distal femur fracture vascular injury.jpg
http://upload.orthobullets.com/topic/1041/images/hoffa fracture.jpg
http://upload.orthobullets.com/topic/1041/images/radiographs blade plate.jpg
Introduction
  • Epidemiology
    • traditionally young patients but increasing in geriatric population
    • bimodal distribution: young, healthy males, elderly osteopenic females
    • periprosthetic fractures becoming more common
  • Mechanism
    • young patients
      • high energy with significant displacement
    • older patients
      • low energy, often fall from standing, in osteoporotic bone, usually with less displacement
Anatomy
  • Osteology
    • distal femur becomes trapezoidal in cross section towards knee
    • medial condyle extends more distal than lateral
    • posterior halves of both condyles are posterior to posterior cortex of femoral shaft
    • anatomical axis of distal femur is 6-7 degrees of valgus 
    • lateral cortex of femur slopes ~10 degrees, medial cortex slopes ~25 degrees in axial plane 
  • Pathomechanics
    • gastrocnemius: extends distal fragment (apex posterior)
    • hamstring and extensor mechanism: cause shortening
    • adductor magnus: leads to distal femoral varus
Classification
  • Descriptive
    • supracondylar
    • intercondylar
  • OTA: 33 
    • A: extraarticular
    • B: partial articular
      • portion of articular surface remains in continuity with shaft
      • 33B3 is in coronal plane (Hoffa fragment)
    • C: complete articular
      • articular fragment separated from shaft
Presentation
  • Physical exam
    • pain, deformity, swelling localizing to distal thigh/knee
    • evaluate skin integrity
    • vascular evaluation 
      • potential for injury to popliteal artery if significant displacement
      • if no pulse after gross alignment restored then angiography is indicated
  • Full trauma evaluation if high energy mechanism
Imaging
  • Radiographs
    • obtain standard AP and Lateral
    • traction views
      • AP, Lateral, and oblique traction views can help characterize injury but are painful for patient
      • in elderly patients, evaluate for any pre-existing knee DJD
      • consider views of the remainder of the extremity to rule out associated injuries
      • consider views of contralateral femur for pre-operative planning and templating
  • CT
    • obtain with frontal and sagittal reconstructions
    • useful for
      • establishing intra-articular involvement
      • identifying separate osteochondral fragments in the area of the intercondylar notch
      • identifying coronal plane fx (Hoffa fx  post
        • 38% incidence of Hoffa fractures in Type C fractures 
      • preoperative planning
    • if temporizing external fixation required, CT obtained after external fixation
  • Angiography
    • indicated when diminished distal pulses after gross alignment restored
    • consider if associated with knee dislocation
Treatment
  • Nonoperative
    • hinged knee brace with immediate ROM, NWB for 6 weeks
      • indications (rare)
        • nondisplaced fractures
        • nonambulatory patient
        • patient with significant comorbidities presenting unacceptably high degree of surgical/anesthetic risk
  • Operative
    • external fixation
      • temporizing measure until soft tissues permit internal fixation, or until patient is stable
      • avoid pin placement in area of planned plate placement if possible
    • open reduction internal fixation
      • indications
        • displaced fracture
        • intra-articular fracture
        • nonunion
      • goals
        • need anatomic reduction of joint
        • stable fixation of articular component to shaft to permit early motion
        • preserve vascularity
      • technique (see below)
      • postoperative
        • early ROM of knee important
        • non-weight bearing or toe touch weight-bearing for 6-8 weeks, up to 10-12 weeks if comminuted
        • quadriceps and hamstring strength exercises 
    • retrograde IM nail 
      • indications
        • good for supracondylar fx without significant comminution
        • preferred implant in osteoporotic bone
        • traditionally, 4 cm of intact distal femur needed but newer implants with very distal interlocking options may decrease this number, can perform independent screw stabilization of intercondylar component of fracture around nail
    • distal femoral replacement
      • indications
        • unreconstructable fracture
        • fracture around prior total knee arthroplasty with loose component
Surgical Techniques
  • ORIF Approaches
    • anterolateral
      • fractures without articular involvement or with simple articular extension
      • incision from tibial tubercle to anterior 1/3 of distal femoral condyle
      • extend up midlateral femoral shaft as needed
      • minimally invasive plate osteosynthesis: small lateral incision, slide plate proximally, use stab incisions for proximal screw placement
    • lateral parapatellar
      • fractures with complex articular extension
      • extend incision into quad tendon to evert patella
      • can be used for Hoffa fracture
    • medial parapatellar 
      • typical TKA approach
      • used for complex medial femoral condyle fractures
    • medial/lateral posterior
      • used for very posterior Hoffa fragment fixation
      • patient placed in prone position
      • midline incision over popliteal fossa
      • develop plane between medial and lateral gastrocnemius m.
      • capsulotomy to visualize fracture
  • Blade Plate Fixation 
    • indications
      • not commonly used, technically difficult
      • contraindicated in type C3 fractures
    • technique
      • placed 1.5 cm from articular surface
  • Dynamic Condylar Screw Placement 
    • indications
      • identical to 95 degree angled blade plate
    • technique
      • precise sagittal plane alignment is not necessary
      • placed 2.0 cm from articular surface 
    • cons
      • large amount of bone removed with DCS
      • difficult to place
  • Locked Plate Fixation 
    • indications
      • fixed-angle locked screws provide improved fixation in short distal femoral block   
      • supracondylar periprosthetic femur fractures in cruciate retaining TKA 
        • TKA component must be well-fixed to proceed with fracture fixation
    • technique
      • lag screws with locked screws (hybrid construct)
        • useful for intercondylar fractures (usually in conjunction with locked plate) 
        • useful for coronal plane fractures q
        • helps obtain anatomic reduction of joint
        • required in displaced articular fractures q
    • pros
      • percutaneous lateral application can minimize soft tissue stripping and obviate need for medial plate
    • cons
      • potential to create too stiff a construct leading to nonunion or plate failure
  • Non-fixed angle plates
    • indications
      • now largely obsolete due to tendency for varus malalignment
  • Retrograde interlocked IM nail  
    • indications
      • good for supracondylar fractures without significant comminution
      • preferred implant in osteoporotic bone
      • short nail rarely indicated, implant should at least reach lesser trochanter
    • approach
      • medial parapatellar
        • no articular extension present
          • 2.5 cm incision parallel to medial aspect of patellar tendon
          • stay inferior to patella
          • no attempt to visualize articular surface
        • articular extension present
          • continue approach 2-8 cm cephalad
          • incise extensor mechanism 10 mm medial to patella
          • eversion of patella not typically necessary
          • need to stabilize articular segments prior to nail placement
    • pros
      • requires minimal dissection of soft tissue
    • cons
      • less axial and rotational stability
      • postoperative knee pain
Complications
  • Symptomatic hardware
    • lateral plate
      • pain with knee flexion/extension due to IT band contact with plate
    • medial screw irritation
      • excessively long screws can irritate medial soft tissues
      • determine appropriate intercondylar screw length by obtaining an AP radiograph of the knee with the leg internally rotated 30 degrees
  • Malunions 
    • most commonly associated with plating, usually valgus
    • functional results satisfactory if malalignment is within 5 degrees in any plane
  • Nonunions 
    • up to 19%, most commonly in metaphyseal area, with articular portion healed (comminution, bone loss and open fractures more likely in metaphysis)
    • decreasing with less invasive techniques
    • treatment with revision ORIF and autograft indicated 
    • consider changing fixation technique to improve biomechanics
  • Infection
    • treat with debridement, culture-specific antibiotics, hardware removal if fracture stability permits
  • Implant failure
    • up to 9%
    • titanium plates may be superior to stainless steel
    • most likely due to improper bridge plating techniques 
 

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