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 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 external fixation 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 retrograde intramedullary nail 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 and distal femoral replacement indications arthroplasty preexisting osteoarthritis with amenable fracture pattern 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 reduced longevity 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