- See:
-
Post Operative Care and Compications:
- Discussion:
- a common lateral plateau frx;
- 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);
- Non Operative Management:
- 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:
- > 8 mm of depression, esp. if knee is unstable;
-
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;
- 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;
- Complications of Surgically Rx'ed Fractures;
-
AVN
-
Loss of Reduction:
-
Loss of Reduction of more than 4 mm occurs in 14% of pts;
- results from inadequate support under elevated fragments;
- Post Operative Care and Compications:
- elevated articular surface must be protected against pressure from
femoral condyle to prevent redepression;
- 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;
- 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;
- Radiographs:
- degree of joint involvement may vary, from small central plateau depression to
fracture depression involving the whole plateau;
- Non Operative Rx:
- 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;
- Operative Rx:
-
PreOp Planning
- if surgery is planned, consider properative MRI;
- w/ valgus instability, ORIF is considered;
- 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;
- consider arthroscopic visualization of frx, use of the ACL guide to assist
with the creation of a bone window below the depression;
- the ACL guide, can then assist with elevation of the depressed fragment;
- bone graft is inserted from below, and following this a
6.5 mm cancellous
screw is inserted below the graft to provide support;
- Post Op Care
