Local Compression Frx: (Type III frx) : Wheeless' Textbook of Orthopaedics

- Discussion:
    - involves central or peripheral depression of frx of lateral plateau w/o associated lateral wedge fracture;
    - it usually occurs from minimal impact on weak osteoporotic bone;
- commonly affects older age groups (55-60 yrs) w/ marked osteoporosis;
- stability of joint is rarely affected & excellent function is expected if there is minimal joint incongruity;
    - look for a localized depression in the articular surface;
    - flexion angle of the knee at injury determines depth of depression
- if knee is extended, depression is limited to about 6 mm.
- if knee is flexed > 30 deg, depression may be as much as 30 mm;
    - usually central depression frx are stable due to intact peripheral ligaments;

- Radiographs:
- location & depth of depression should be determined by CT (as either anterior, middle, or posterior);
- degree of joint involvement may vary, from small central plateau depression to fracture depression involving the whole plateau;

- Non Operative Management:
- most low energy type III frx in elderly pts w/ poor bone stock should be treated non-operatively;
- if no valgus instability is found, it is safe to treat such a frx, w/ early motion but no wt bearing;
- need to restore knee movement & strength early and disregarding articular depressions;
- local compression fractures of the lateral plateau with depression of up to 8-10 mm do well with non operative treatment;
- usually mild valgus deformity and a few degrees of instability will develop;
- wt bearing is not allowed for 8 weeks;
- duing its application the cast brace is stressed into varus to prevent femoral condylar pressure on the elevated plateau;

- Operative Management:
- PreOp Planning
- indications:
            - w/ valgus instability, ORIF is considered;
          - > 8 mm of depression, esp. if knee is unstable;
    - if depression is severe, articular fragments should be elevated bone grafted, and the lateral cortex supported with a butress plate;
- w/ central depression frx, lateral cortex is intact circumferentially, & theoretically, there is no need for butress plate;
    - arthroscopic assisted reduction is most useful w/ depressions of <12 mm;
      - elevate fragments, pack bone grafts under articular surface;
      - tibial tunnel ACL guide can be useful for creating a cortical window and allowing accurate elevation of bone fragments;
    - internal fixation:
            - references:
                  - Percutaneous Screw Fixation of Tibial Plateau Fractures.
                  - Closed reduction and percutaneous screw fixation for tibial plateau fractures
                  - Indirect reduction and percutaneous screw fixation of displaced tibial plateau fractures.

    - post op:
            - protect the knee in a cast brace, & begin ROM during first 8 weeks;
      - then light wt bearing is used until 12 weeks;
    - note: possibility of fluid extravasation and compartment syndrome;
     - w/ > 12 mm depression, consider need for open reduction, elevation of frx depression and bone grafting to support the surface;
            - 6.5 cancellous screws can be inserted below the bone graft to provide support and prevent subsidence;
   - consider use of an interference screw thru the anteromedial window, which allows a slow driving force to raise the depression; (see milagro)

- Post Operative Care and Compications:
- elevated articular surface must be protected against pressure from femoral condyle to prevent redepression;
    - Loss of Reduction:
- loss of reduction of more than 4 mm occurs in 14% of pts;
              - results from inadequate support under elevated fragments;
    - AVN

- Misc:
    - Cast Bracing:
- reliable external support is required in the post op period to counteract femoral condylar pressure;
- redepression will frequently occurr w/ long leg cast;
- instead pt's require well fitted varus cast brace;
- cast bracing minimizes pressure against elevated articular surface;
- to be effective, brace is placed in genu varus stress as hinges are affixed;
- this is maintained for 8-10 weeks, at which time, elevated fragments will have revascularized & will have developed bony healing;
    - wt bearing is delayed until bony healing is advanced;
          - watch for redepression, AVN of frx fragments, & valgus instability;
   - most frequent of these problems is redepression;
      - occurs from inadequate postoperative protection of elevated articular surface from the femoral condylar pressure;
    - more than 3 mm of redepression usually results in noticeable valgus deformity and instability