Unstable Intertrochanteric Fractures


 - See:
        - Radiographic Findings 
        - Sliding Hip Screw w/ Unstable Frx

- Discussion:
    - it is important prior to reduction to distinguish between unstable and stable frx intertroch fractures;
    - w/ cortical instability on one side of frx owing to cortical overlap or destruction, frx tends to collapse in direction of instability;
          - truly stable intertrochanteric frx, therefore, is one that, when reduced, has cortical contact w/o a gap medially & posteriorly;
          - this contact prevents frx displacement into varus or retroversion;
    - in some cases, an unstable frx pattern may be missed due to an inadequate lateral radiograph, which interferes w/ assessment of size postero-medial comminution and presence of coronal split in the greater trochanteric 4 part frx;
    - the dreaded complication of unstable intertrochanteric fractures is migration of the femoral head into varus and retroversion;
    - internal fixation of frx in varus position: 
          - frx stability exists exits in the displaced position because of medial contact between the two major fragments;
          - this type of fixation is the least satisfactory type of nonanatomical reduction because of the limp and shortening that result from union in the displaced varus position;
    - hazards:
          - avoid treating unstable fractures like stable ones (ie. avoid the following);
                - in this case, there was unacceptable frx opposition;
          - frx shortening of 6-7 mm does not affect ambulation but shortening of 13-18 mm of shortening will affect ambulation; 
                - frx shortening or collapse will affect the abductor lever arm and will lead to abductor weakness;


- Types of Unstable Frx
      - lesser trochanter frx
           - stability is lost when the less troch contains a portion of the calcar;
      - greater trochanter:
           - comminution of greater trochanter & adjacent posterolateral shaft predispose to medial shaft migration;
           - there is no contact between proximal & distal frag owing to comminution and displacement of frx frag medially and posteriorly;
      - type IV frx (see classification)
           - when using a 150 deg plate, the head and neck segments often must be placed in valgus inorder for the guide wire to reach the center of the femoral head;
           - this valgus positioning tends to open up the postero-medial gap, in which case a modified Sarmiento osteotomy is needed inorder to re-establish frx opposition;
           - using a 135 deg plate, a lesser amount of valgus positioning was required and therefore a smaller posteromedial gap was created;
      - 4 part frx:
           - as noted by Den Hartog BD, et al. (1991), mean load to failure was increased in unstable intertrochanteric fractures by re-establishment of medial contact (using an osteotomy, use of a high angle plate, and placement of the lag screw in center of the femoral head;
           - w/ a severely comminuted 4 part frx (in which case, it is not possible to convert the unstable frx to a stable one), one can consider a type of modified Dimon and Hughston's Osteotomy;
      - reversed obliquity:
           - tendency toward medial displacement of shaft 2nd to hip adductors; 
           - ref: Treatment of the unstable intertrochanteric fracture. Effect of the placement of the screw, its angle of insertion, and osteotomy 

                 



- IM Hip Screw 
   

- Treatment of Unstable Frx with Sliding Hip Screw and Plate:
    - compared to a medial displacement osteotomy, an anatomic reduction is more able to load the medial cortex in patients w/ an unstable intertrochanteric fracture;
          - often there will be posterior displacement of the distal fragment, which requires a strong assistant to lift the fragment upwards with a bone hook;
          - references:
                 Biomechanical evaluation of anatomic reduction verus medial displacement osteotomy in unstable intertrochanteric fractures
    - stability may be restored by osteotomy or medial displacement;
          - Sarmento's osteotomy
          - Dimon and Hughston's technique
          - Wayne County Reduction
    - strength of the fragment implant assembly is determined by:
          - bone quality
          - fragment geometry
          - reduction
          - implant placement
          - implant design
                - trochanteric stabilization plate is designed to fit onto the 135 deg DHS plate and helps prevent excessive lateral sliding of the proximal frx fragments (and excessive shortening);
                - frx shortening of 6-7 mm does not affect ambulation but shortening of 13-18 mm of shortening will affect ambulation;
                      - frx shortening or collapse will affect the abductor lever arm and will lead to abductor weakness;
                - references:
                      - Dynamic hip screw with trochanteric stabilizing plate in the treatment of unstable proximal femoral fractures: A comparitive study with Gamma Nail and Compression hip screw
                      - Clinical results using the trochanter stabilizing plate (TSP): The modular extension of the dynamic hip screw (DHS) for internal fixation of selected unstable intertrochanteric fractures



      case examples:
           
           

              



Axial loading studies of unstable intertrochanteric fractures of the femur.

Unstable intertrochanteric/subtrochanteric fractures of the femur.

Medial displacement osteotomy for unstable intertrochanteric fractures. Twenty years later.

Biomechanical evaluation of anatomic reduction versus medial displacement osteotomy in unstable intertrochanteric fractures.

Treatment of unstable intertrochanteric and subtrochanteric fractures in elderly patients. Primary bipolar arthroplasty compared with internal fixation.

Unstable intertrochanteric fractures of the hip. Treatment with Ender pins compared with a compression hip-screw.

Bipolar prosthetic replacement for the management of unstable intertrochanteric hip fractures in the elderly.

Treatment of the unstable intertrochanteric fracture. Effect of the placement of the screw, its angle of insertion, and osteotomy 

How effective are osteotomies for unstable intertrochanteric fractures?

Dynamic hip screw with trochanteric stabilizing plate in the treatment of unstable proximal femoral fractures: A comparitive study with Gamma Nail and Compression hip screw

Integrity of the Lateral Femoral Wall in Intertrochanteric Hip Fractures: An Important Predictor of a Reoperation. 

Femoral shortening in intertrochanteric fractures. A comparison between the Medoff sliding plate and the compression hip screw



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

Last updated by Data Trace Staff on Tuesday, September 18, 2012 3:32 pm