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Updated: Feb 14 2024

Distal Femur Fractures

Images
https://upload.orthobullets.com/topic/1041/images/Xray - Lat - Hoffa fragment_moved.jpg
https://upload.orthobullets.com/topic/1041/images/distal femur fracture vascular injury.jpg
https://upload.orthobullets.com/topic/1041/images/hoffa fracture.jpg
https://upload.orthobullets.com/topic/1041/images/radiographs blade plate.jpg
  • Summary
    • Distal femur fractures are traumatic injuries involving the region extending from the distal metaphyseal-diaphyseal junction to the articular surface of the femoral condyles.
    • Diagnosis is made radiographically with CT studies often required to assess for intra-articular extension.
    • Treatment is generally operative with ORIF, intramedullary nail, or distal femur replacement depending on available bone stock, age of patient, and patient activity demands.
  • Epidemiology
    • Incidence
      • common
        • 3-6% of femur fractures
          • <1% of all fractures
    • Demographics
      • bimodal distribution
        • young healthy males
        • elderly osteopenic females
  • Pathophysiology
    • Mechanism
      • young patients
        • high energy with significant displacement
      • older patients
        • low energy, often fall from standing, in osteoporotic bone, usually with lesser degree of displacement
  • Anatomy
    • Osteology
      • anatomical axis of the distal femur is 6-11 degrees of valgus
        • medial condyle extends more distal than lateral
      • distal femur becomes trapezoidal in cross-section towards the knee
        • lateral cortex of femur slopes ~10 degrees, medial cortex slopes ~25 degrees in the axial plane
      • posterior halves of both condyles are posterior to the posterior cortex of femoral shaft
    • Muscles
      • key deforming forces
        • quadriceps
        • hamstrings
        • adductor magnus
        • gastrocnemius
    • Ligaments
      • anterior cruciate ligament (ACL)
      • posterior cruciate ligament (PCL)
      • medial collateral ligament (MCL)
      • lateral collateral ligament (LCL)
    • Biomechanics
      • hamstring and quadriceps
        • cause the femur to shorten
      • adductor magnus
        • leads to distal femoral varus or valgus
          • direction of deformity is dependent on the location of comminution and the relation of fracture lines to the adductor tubercle
      • gastrocnemius
        • extension at the fracture site (apex posterior)
        • rotation of condyles when an intercondylar split is present
  • Classification
    • Descriptive
      • supracondylar
      • intercondylar
    • OTA: 33
      • A: extraarticular
      • B: partial articular
        • portion of the articular surface remains in continuity with shaft
        • 33B3 is in the coronal plane (Hoffa fragment)
      • C: complete articular
        • articular fragment separated from the shaft
  • Presentation
    • History
      • patients commonly present after fall or traumatic event
    • Symptoms
      • common symptoms
        • pain of distal femur that is made worse with knee movement
        • inability to weight-bear
    • Physical exam
      • inspection
        • tenderness, swelling, ecchymosis of the distal thigh and knee
        • varus or valgus deformity
        • knee effusion may be present with intraarticular involvement
        • evaluate for wounds concerning for an open fracture
          • 5-10% of supracondylar fractures
      • neurovascular exam
        • vascular evaluation
          • potential for injury to popliteal artery if significant displacement
          • Ankle-brachial index (ABI) should be performed if there is a concern for vascular injury
            • angiography is indicated if <0.9
            • >0.9 = 99% negative predictive value
            • <0.9 = 97% specific and 95% sensitive for major arterial injury
  • Imaging
    • Radiographs
      • recommended views
        • AP
        • lateral
      • additional views
        • traction views
          • AP, lateral, and oblique traction views can help characterize injury but are painful for the patient
        • adjacent joints
          • obtain imaging of entire femur to rule out associated injuries
        • contralateral femur
          • consider views of the contralateral femur for pre-operative planning and templating
      • findings
        • can be difficult to visualize intraarticular extension
        • condyles are malrotated in sagittal plane with respects to each other
        • sagittal intra-articular splut is most common
        • Hoffa fracture
          • intra-articular distal femoral fracture in the coronal plane
          • 38% incidence
          • seen on the lateral view
          • missed in up to 31% of cases
          • lateral condyle fractures
            • 80% incidence
        • in elderly patients, evaluate for any pre-existing knee DJD
    • CT scan
      • indications
        • preoperative planning
        • evaluating intra-articular involvement
        • after external fixation to assess pattern, comminution, and intraarticular extension
      • findings
        • separate osteochondral fragments in the area of the intercondylar notch
        • coronal plane fracture (Hoffa fracture) in 40%
        • lateral femoral condyle fractures in 80%
    • Angiography
      • indications
        • ankle-brachial index (ABI) <0.9
        • obvious signs of vascular injury
          • i.e., hard and soft signs (pulselessness, rapidly expanding hematoma, massive bleeding, etc.)
      • findings
        • identifies vascular segments with diminished flow
        • vascular injury
          • displaced distal femur fractures may result in injury to the popliteal artery
  • Treatment
    • Nonoperative
      • immobilization with hinged knee brace
        • indications (rare)
          • stable, nondisplaced fractures
          • nonambulatory patient
          • patient with significant comorbidities presenting an unacceptably high degree of surgical/anesthetic risk
        • outcomes
          • variable and dependent on multiple factors including patient characteristics and fracture pattern
    • Operative
      • closed reduction and external fixation (ExFix)
        • indications
          • temporizing measure to restore length, alignment, and stability
            • unstable, polytrauma
            • soft tissues not amenable to surgical incisions and internal fixation, or until the patient is stable
            • contamination requiring multiple debridements
          • definitive treatment
            • severe open and/or comminuted fractures
            • patients unstable for surgery
        • outcomes
          • variable and dependent on multiple factors including patient characteristics, fracture pattern, and degree of soft tissue injury
          • 92-100% union rates reported at an average of 4-6 months when used as definitive treatment
      • open reduction internal fixation (ORIF)
        • indications
          • displaced fracture
          • intra-articular fracture
            • traditional 95 degree devices contraindicated in Hoffa fractures
          • periprosthetic fracture with osteoporotic bone
          • nonunion
          • fixed-angle plates required for metaphyseal comminution
            • non-fixed angle plates are prone to varus collapse
        • outcomes
          • variable and dependent on multiple factors including patient characteristics and fracture pattern
          • dual plating (lateral + medial plate) offers greatest degree of axial and torsional stiffness
          • nonunion rates up to 18%
          • no difference in fixation failure, reoperation rates, or nonunion with early weightbearing as tolerated and protected weightbearing in extra-articular distal femur fractures 
      • closed reduction and intramedullary fixation (IMN)
        • indications
          • extraarticular fractures
          • simple intraarticular fractures
          • periprosthetic fractures with implants with an "open-box" design
            • distal femoral replacements do not allow retrograde nail fixation
          • traditionally, 4 cm of intact distal femur needed but newer implants with very distal interlocking options may decrease this number
            • independent screw stabilization of intraarticular components placed around nail
        • outcomes
          • variable and dependent on multiple factors including patient characteristics and fracture pattern
          • high union rates reported, more symmetric callus formation compared to plates
          • reduced rates of malunion and higher patient satisfaction compared to ORIF has been reported
      • arthroplasty
        • indications
          • preexisting osteoarthritis with amenable fracture pattern
          • techniques
            • total knee arthroplasty
            • distal femoral replacement
              • low demand patients
                • un-reconstructable fracture
                • fracture around prior total knee arthroplasty with loose component
                • osteoarthritis
        • outcomes
          • variable and dependent on multiple factors including patient characteristics and fracture pattern
          • may have improved ambulatory status and decreased nonunion compared to other methods of fixation
            • up to 20% of patients are wheelchair bound at one-year following internal fixation
          • reduced longevity compared with internal fixation
          • similar surgical complication rates compared with internal fixation
          • similar reoperation rates compared with internal fixation
          • allows immediate weight bearing
  • Techniques
    • Hinged knee brace
      • technique
        • full time bracing for 6-8 weeks
        • closed-chain ROM exercises at 3-4 weeks
        • restricted weight-bearing until evidence of fracture union
        • serial radiographs to assess for displacement
      • complications
        • wounds from immobilization and bracing
        • knee stiffness
    • External Fixation
      • technique
        • avoid pin placement in the area of planned plate placement, if possible
      • complications
        • pin tract infections
    • Open Reduction Internal Fixation (ORIF)
      • approach
        • lateral
          • suitable for all fracture types
          • arthrotomy for direct reduction of articular components
        • minimally invasive lateral modified anterior (swashbuckler)
          • best when used for extraarticular fractures
          • distal incision large enough to insert plate sub-muscularly
          • screws placed through smaller proximal incisions
          • midline anterior incision that angles slightly lateral
          • lateral parapatellar arthrotomy
          • facilitates articular and lateral distal femur exposure
        • lateral parapatellar
          • fractures with complex articular extension
          • extend incision into quadriceps tendon to evert patella
          • can be used for Hoffa fracture
        • medial parapatellar
          • used for complex medial femoral condyle fractures
        • medial
          • most often used for type B2 and B3 patterns
          • can be used to augment fixation with medial plate in type C3 patterns
        • medial/lateral posterior
          • used for very posterior Hoffa fragment fixation
          • patient placed in the prone position
          • midline incision over the popliteal fossa
          • develop a plane between medial and lateral gastrocnemius
          • capsulotomy to visualize fracture
      • technique
        • goals
          • anatomic joint reduction with rigid fixation
            • restore articular surface before fixation of extraarticular component
          • stable fixation of articular component to diaphysis for early ROM
          • preservation of vascularity
        • direct visualization of the joint allows perfect reduction of intraarticular fractures with lag screw fixation before attaching the articular block to the proximal fragment
          • Hoffa fragments can be captured with an anterior to posterior screw
        • locking plates
          • allows better control of coronal plate compared to 95º angled blate plate and dynamic condylar screw
          • multi-plane screw trajectory allows fixation of coronal (Hoffa) fragments
          • lag screws with locked screws (hybrid construct)
            • intercondylar fractures (usually in conjunction with locked plate)
            • coronal plane fractures
          • locking screw constructs don't rely on bone-plate contact for stability
            • helpful when pre-contoured plates do not precisely match patient anatomy
          • potential to create too stiff of construct leading to nonunion or plate failure
          • NOT an appropriate construct for isolated medial femoral condyle fractures
        • non-fixed angle plate
          • risk of varus malalignment
            • high risk with metaphyseal comminution
        • blade plate fixation
          • requires precise initial implantation of the blade into the distal fragment
          • contraindicated in type C3 fractures
          • may provide poor fixation osteoporotic bone
        • dynamic condylar screw
          • precise sagittal plane alignment is not necessary as plate rotates around the barrel
          • large amount of bone removed, may provide poor fixation in osteoporotic bone
      • complications
        • nonunion
        • knee stiffness
    • Retrograde intramedullary nail
      • approach
        • transtendon approach
          • mid substance longitudinal patellar tendon split
        • medial parapatellar
          • no articular extension
            • 2.5 cm incision parallel to medial aspect of patellar tendon
            • no attempt to visualize articular surface
          • articular extension present
            • continue approach 2-8 cm cephalad
            • incise extensor mechanism 10 mm medial to the patella
            • eversion of patella not typically necessary
            • need to stabilize articular segments before nail placement
      • technique
        • insertion requires ≥70º knee flexion
        • articular reduction and fixation before nail placement
          • lag screws placed out of the intended IMN path
        • starting point at the superior margin of Blumensaat line (lateral) and center of intercondylar notch (AP)
        • blocking screws facilitate reduction and strengthen the construct
        • short nails are rarely indicated
          • implant should reach lesser trochanter to reduce risk of vascular injury
      • complications
        • postoperative knee pain
        • IMN for periprosthetic fractures may result in recurvatum deformity
          • box design requires a posterior starting point
    • Arthroplasty and distal femoral replacement
      • approach
        • extensile anterior, lateral, or medial
          • use previous scar if possible
      • technique
        • resect fracture to allow full weight-bearing
      • complications
        • mechanical failure
          • endoprosthetic metal or polyethylene component fracture
          • aseptic loosening
          • modular component disassociation
          • polyethylene wear synovitis
  • Complications
    • Knee pain/stiffness
      • treatment
        • early ROM
        • physical therapy
    • Symptomatic hardware
      • risk factors
        • lateral plate
          • pain with knee flexion/extension due to IT band contact with the plate
        • medial screw placement
          • 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
      • treatment
        • hardware removal
    • Malunions
      • risk factors
        • common deformities after plating include rotation, hyperextension (recurvatum), and coronal malalignment
          • "golf-club" deformity arises from medial translation of the articular block when the plate is placed too posterior distally
        • percutaneous submuscular fixation with pre-contoured locking plate
          • often rotational malalignment
        • malalignment is more common with IM nails
      • treatment
        • revision internal fixation with osteotomy
        • functional results satisfactory if malalignment is within 5 degrees in any plane
    • Nonunions
      • incidence
        • up to 19%, most commonly in metaphyseal area with articular portion healed (comminution, bone loss and open fractures more likely in metaphysis)
      • risk factors
        • associated with soft tissue stripping in metaphyseal region
      • treatment
        • revision ORIF and autograft indicated
        • consider changing fixation technique to improve biomechanics
    • Infection
      • risk factors
        • diabetics with foot ulcers
      • treatment
        • debridement
        • culture-specific antibiotics
        • hardware removal if fracture stability permits
    • Implant failure
      • incidence
        • up to 9%
      • risk factors
        • improper bridge plating techniques
        • short working length construct
        • stainless steel implants may be inferior to titanium
    • Loss of fixation
      • varus collapse (most common)
        • plate fixation associated with toggling of distal non-fixed-angle screws used for comminuted metaphyseal fractures
        • IM nail fixation
      • Proximal (diaphyseal) screw failure
        • associated with short plates and nonlocked diaphyseal fixation
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