Distal Femoral Shaft Fractures


- See:
      - Femoral and Tibial Traction Pins
      - Supracondylar Femoral Fractures

- Discussion:
    - failure of the nail to fill the canal of either the proximal or distal fragment, may lead to postoperative instability;
    - distal fractures within 10 cm of the joint line often can be treated successfully with standard IM nailing;

- Traction Pins:
    - when treating distal fractures, the knee must be flexed and a distal femoral traction pin must be inserted;
    - flexed knee position releaxes the posterior knee capsule and the gastrocnemius muscle, thereby avoiding a hyperextension
            deformity at the fracture, which can prevent fracture reduction;
    - femoral traction pin is inserted anteriorly just proximal to the adductor tubercle, and is placed from the inframedial to 
            superolateral side to pull the fracture out of valgus angulation;
    - because the distal femoral traction pin needs to be placed very distal and anterior, consider the use of fluoroscopy to
            avoid penetration into the knee joint;
    - note: in the lateral position, the weight of the leg produces a valgus angulation at the fracture site;
    - if the deformity is not corrected during the insertion of the nail, the nail will be driven into the medial femoral condyle, and
            a valgus deformity will result;
    - finite element analysis of interlocking nails, have revealed that if a frx is located w/in 5 cm of this hole, stresses are generated in the
            nail above its endurance limit;

- Reduction:
    - frx of distal third of the shaft pose a special reduction problem;
    - in supine position, the distal fragment angulates posteroirly and must be supported with a crutch;
    - in lateral position, the dstal fragment sags into valgus angulation;

- Reaming:
    - faster union may be achieved in distal femoral shaft fractures which have been reamed vs. those that have not been reamed;
            - in these frxs, reaming allows insertion of a larger nail, which allows more rigid fixation between the implant and the bone;

- IM Nail Technical Considerations:
    - tend to sag into a valgus position;
    - distal purchase of the nail is critical for stability;
    - major loading of this region of femur, along w/ inadequacy of endosteal purchase on distal frag, results also in a higher non union
          rate w/ interlocking nails than is seen in midshaft fractures;
          - thus, the cancellous bone is not reamed;
    - distal third frx especially require minimal 1.0 to 1.5 mm overreaming of proximal fragment to accomodate the variable degree of
          anterior femoral bow that might be present;
    - nail is driven thru old epiphyseal scar to level of intercondylar notch, hence an appropriately sized nail is extremely important;
    - after nail has been driven a few mm across frx, traction may be decr sufficiently to allow impaction of frx as nail is driven distally;
    - frx angulation is also possible intraoperatively if the nail is driven eccentrically out of alignment w/ longitudinal axis of the canal;
    - w/ distal fractures the nail may be driven into the medial or lateral condyles resulting in either a valgus or varus deformity;
    - if full correction of this problem is not achieved before guide pin insertion, the nail may be driven into the medial femoral
              condyle, resulting in a valgus deformity;
    - guide pin should be aimed directly at intercondylar notch on AP view of femur before reaming and nailing of distal fragment;
    - reaming of distal fragment down to anticipated distal tip of nail is unnecessary and may comprimise the purchase of nail on
              cancellous bone of the distal third of the shaft;

- Length of Nail:
    - distal end of medullary nail should be at superior pole of patella in isthmal level fractures &, for more distal fractures, just
              proximal (approx 3 cm) to the intercondylar notch;
    - make allowance for the slight overdistraction at the fracture site;
    - to prevent problems w/ protrussion into gluteal muscles, it should not extend above the greater trochanter;
    - in some cases further impaction occassionally occurs when severly comminuted fractures are later dynamized;
    - this should be considered to prevent later nail migration into the knee or nail protrussion out of the proximal femur

- References:

  Nails or plates for fracture of the distal femur?

  Fatigue fracture of the interlocking nail in the treatment of fractures of the distal part of the femoral shaft.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, July 19, 2016 6:27 am