Distal Femur Fractures Presentation and Treatment

Distal femur fractures have traditionally been associated with young patients but are increasing in geriatric population. They are commonly found in  young, healthy males and  elderly osteopenic females.  With increased use of prostheses,  periprosthetic fractures becoming more common

These fractures require anatomically stable fixation.

The fractures represent high energy injury in young patients whereas are a low energy injuries in old people.

Anatomy of Distal Femur

The distal femur is the area where the stronger diaphyseal bone meets the thinner and weaker metaphyseal bone.

The  anatomical  axis of  the  knee  joint  does  not coincide with the weight-bearing  axis which crosses  the  center  of  the  femoral  head  and  the center of the knee. The anatomical axis is in valgus and subtends  an angle of 81° with the knee joint.

The distal femur, when viewed in cross-section, is seen to be a trapezoid. Anteriorly, the distance between the medial and lateral wall is less than  the  distance  posteriorly.  The medial  wall has the  greater  slope of the two, and is inclined at 25° to the vertical.

The projected width  of the femur on a radiograph  is the maximum  width and represents  the most posterior  distance between the medial and lateral wall.

Medial condyle extends more distal than lateral condyle. Posterior halves of both condyles are posterior to posterior cortex of femoral shaft.

Different muscles attached to the condylar area cause different deformities of the distal fragment.

• Gastrocnemius: extends distal fragment (apex posterior)
• Hamstring and extensor mechanism: cause shortening by pulling proximally
• Adductor magnus: leads to distal femoral varus

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Classification of Distal Femur Fractures [AO/ASIF]

• A – Extra-articular [Supracondylar Fractures]

  • A1 – Simple
  • A2 – Metaphyseal, wedge
  • A3 – Metaphyseal, complex

• B – Partial articular

  • B1 – Lateral condyle (sagittal fracture line)
  • B2 – Medial condyle (sagittal fracture line)
  • B3 – Frontal (coronal fracture line) {Hoffa’s fracture}

• C – Complete articular

  • C1 – Articular and metaphyseal segments, simple fractures
  • C2 – Articular simple, but metaphyseal multifragmentary fractures
  • C3 – Articular and metaphyseal segments, multifragmentary fractures

Clinical Presentation

Patients present with pain, deformity, weakness, and inability to use the leg. Young patients often sustain high energy trauma and elderly patients usually have a history of a fall.

Patient needs to evaluated for skin integrity, vascular status in the affected limb.

Full trauma evaluation is warranted if the injury is due to a high energy mechanism.

Any fractures in other areas must be identified. High alert is required for identification of compartment syndrome.

Imaging Studies

X-rays

Patients with Distal femur femur fractures require anteroposterior and lateral . Anteroposterior, lateral, and oblique traction views can help characterize injury but are painful

Elderly patients should be evaluated for degenerative joint disease.

Suspected injuries in same limb or other body parts should be evaluated.

CT

CT scan is very useful in intra-articular fractures. It helps to

• Identify intra-articular fractures in both frontal and sagittal reconstructions.
• Establishing intra-articular involvement where x-ray does not clearly tell
• Identification of separate osteochondral fragments in the area of the intercondylar notch
• Identification of Hoffa’s fracture which can be easily missed on xrays.

Angiography

Indicated in suspected arterial injury and associated  knee dislocation.

Treatment of Distal Femur Fractures

Essentially all distal femur fractures require operative intervention because of the severe potential risks of prolonged bed rest.

Patients who are bedridden or nonambulatory with nondisplaced or minimally displaced fractures  may not be candidate for surgery.

Patients with severe life-threatening or other medical problems in which the risks of anesthesia are high may also be treated nonoperatively.

This patients can be treated with plaster immobilization followed by hinged knee brace.

Surgery

If the  fracture  is open  or  if there  is an  associated vascular injury, the patient needs to be operated immediately. The limb  should  be splinted  while the  patient awaits surgery.

Goals in the treatment of all intra-articular fractures are

• Accurate anatomical reduction
• Absolutely stable  fixation
• Atraumatic reduction,
• Stable reduction of the metaphyseal  component
• Early motion

Indications for surgery

Absolute indications

• Unicondylar Fracture
• Fracture in the coronal plane [Hoffa fracture]
• Open Intra-articular Fractures
• Associated Neurovascular Injuries
• Ipsilateral Fracture of the tibial Plateau or patellar Fracture
• Ipsilateral Fracture of the Tibia (The Floating Knee)
• Multiple Injuries
• Pathological Fractures

Different types of fixations

External fixation

• Usually temporary measure until soft tissues permit internal fixation, or until patient is stable
• Pin placement should be avoided in the area of planned plate placement

Open reduction internal fixation

Open reduction and internal fixation is used in displaced, intra-articular fractures and nonunion.

It provides anatomic reduction of joint and  stable fixation of articular component to shaft to permit early motion.

Implant choice may vary with the fracture.

• For extra-articular distal femur fractures (A1, A2, A3) or those with condylar fragmentation (C1, C2) –
  • Dynamic condylar screw
  • Condylar blade plates
• For condylar fractures (B1, B2, B3), a 4.5-mm
  • T buttress plate with or without lag scrw fixation
  • Condylar buttress plate for very distal fractures
• Distal Femoral plates

• • Bridge plating
  • Minimally invasive plating
  • Specially designed periarticular plates
  • Fixed-angle screw plates

Closed/open reduction and Retrograde IM nailing

This is a good option for  good for supracondylar fractures without significant comminution. It is also a preferred implant in osteoporotic bone,

Distal femur nails also necessitate restoration of the condyles before nail placement.

Distal femoral Replacement

This is used in  unreconstructable fracture or fracture with prior total knee arthroplasty with loose component

Postoperative physical therapy is usually required.

Patients need to be monitored until the bone is healed.

Approches to Knee in Distal Femur Fractures

Anterolateral Approch

• Articular fractures
• For minimally invasive plate osteosynthesis

Lateral parapatellar

• Complex articular fractures
• For Hoffa fracture

Medial parapatellar

Complex medial femoral condyle fractures

Posterior

• Very posterior Hoffa fragment fixation
• Midline incision over popliteal fossa

Complications

Complications of Distal femur femur fractures include the following:

• Nonunion
• Hardware irritation
• Malunions
• Infection
• Implant Failure

 Prognosis

With stable fixation and  anatomic alignment leading to intra-articular congruency, most patients do well. Severely comminuted fractures, poor bone quality, poor reduction and poor fixation worsen the prognosis.

Type C3 fractures are expected to develop significant secondary degenerative changes.

Open fractures have worse prognosis.

References

• Yang RS, Liu HC, Liu TK. Distal femur fractures of the femur. J Trauma. 1990 Mar. 30(3):315-9.
• Parvizi J, Jain N, Schmidt AH. Periprosthetic knee fractures. J Orthop Trauma. 2008 Oct. 22(9):663-71.
• Yoo JD, Kim NK. Periprosthetic fractures following total knee arthroplasty. Knee Surg Relat Res. 2015 Mar. 27 (1):1-9.
• Schatzker J. Distal femur fractures of the femur. In: Schatzker J, Tile M, eds. The Rationale of Operative Fracture Care. New York, NY:. Springer-Verlag. 1987:255-273.
• Tscherne H. Extra-articular fractures of the distal femur. In: Miller ME, Allgower M, Schneider R, Willenegger H, eds. Manual of Internal Fixation. 3rd ed. New York, NY:. Springer-Verlag. 1991:548-51.
• Merchan EC, Maestu PR, Blanco RP. Blade-plating of closed displaced Distal femur fractures of the distal femur with the AO system. J Trauma. 1992 Feb. 32(2):174-8.
• Zehntner MK, Ganz R. Internal fixation of Distal femur fractures after condylar total knee arthroplasty. Clin Orthop. 1993 Aug. (293):219-24.
• Wu CC. Retrograde locked intramedullary nailing for aseptic Distal femur femoral nonunion following failed locked plating. J Orthop Surg (Hong Kong). 2015 Aug. 23 (2):155-9.