- Discussion: Type I Fractures:
- this is the wedge fracture of a lateral plateau;
- it occurs mostly in young people since the dense cancellous bone of lateral plateau resists depression;
- "Minimally Displaced Fractures" (from the Holh Classification)
- frx shows depression or deplacement of < 4 mm;
- note: a frx appearing to be minimally displaced may have been considerably displaced during injury which then became spontaneously reduced;
- Exam:
- knee stability is important in choosing treatment for minimally displaced frx;
- test in full extension and at 20 deg flexion;
- Radiographs:
- if knee is unstable ( > 5 deg instability), stress x-rays are be made to determine whether instability is 2nd to movement at frx site or to ligament injury;
- w/ displaced lateral type I frx, be suspicous of lateral meniscal detachment, and consider ordering MRI;
- Non Operative Management:
- undisplaced frx:
- if undisplaced, these frxs require early motion & protection from wt bearing, because, under stress, displacement may occur;
- cast brace and NWB for 6 to 8 weeks;
- stable displaced frx:
- stability is tested 1st w/ knee extended and then flexed 15 deg
- if such testing shows < 5 deg of instability (compared to nl knee), the knee is considered to be stable;
- if instability is due to frx movement (as seen on x-rays), apply cast brace is to stabilize the leg;
- Indications for Surgery:
- a displace wedge or split frx of lateral plateau, is unstable and is an indication for surgery;
- any degree of condylar widening is an indication for surgery;
- lateral meniscus may become trapped in the frx & will require surgical correction via open arthrotomy;
- Operative Treatment:
- Work Up and PreOp Planning:
- surgical approach:
- consider using a midline incision if ligament repair or if meniscal reattachment is needed along with repair of the fracture;
- if preoperative MRI shows that meniscus is not entraped w/ in frx site, then consider use of percutaneous reduction and screw fixation;
- reduction:
- if the split fragment is depressed, it needs to be brought out to length with use of a femoral distraction;
- the distractor is placed on the same side as the fracture;
- once the fracture fragment has been elevated w/ ligamentotaxis, then medial or lateral displacement can be corrected;
- reduction is achieved w/ percutaneous applied reduction forceps w/ flourscopic assistance;
- consider applying the reduction forceps eccentrically, and then torque the reduction forceps to achieve reduction;
- adequate reduction implies less than 1-2 mm step off;
- depressed fragments:
- make a small window in the metaphyseal cortex and elevate the depressed fragment with a bone tamp;
- fixation:
- percutaneous screws:
- wedge of type I frx of lateral plateau can usually be fixed w/ only cancellous percutaneous lag screws and washers (plates are usually not necessary);
- consider 6.5 mm cancellous screws (over washers) which are placed in a triangular position;
- ref: Combined Arthroscopic Treatment of Tibial Plateau and Intercondylar Eminence Avulsion Fractures
anti-glide screw:
- antiglide screws are typically placed after 1-2 percutaneous lag screws are placed thru the frx fragment;
- antigluide screws (over washers) are placed just distal to the frx edge to prevent distal displacement;
- 4.5 mm cortical screws over washers are typically used;
- butress plate:
- w/ good bone stock, butressing is not required, but in older pts a butress plate is required to prevent redisplacement;
- see: lateral plateau butress plate characteristics:
- typically a 6 hole plate is utilized which will allow three screws to be placed distal to the frx line;
- consider repair collateral ligament damage after fixing fracture;
- see: ligament damage
- Complications of Lateral Type I Plateau Frx:
- type I lateral plataue frx (or "minimally displaced frxs" of lateral plateau are stable (esp if fibula is intact) & require little external support during healing;
- operatively treated frx may fail with inferior toggling of the screws, causing the frx to re-depress
Split Fractures of the Lateral Tibial Plateau: Evaluation of Three Fixation Methods.
The role of arthroscopy in the management of tibial plateau fractures.
Indirect Reduction and Percutaneous Screw Fixation of Displaced Tibial Plateau Fractures.
Tibial Plateau Fractures. A review of operative treatment using AO technique.