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Closing Wedge HTO: Intermedics Plate Fixation

   



- Positioning:
    - sterile tourniquet;
    - supine position, hip bump;
    - foot bump to hold the knee in hyperflexion;

- Incision:
    - inverted L shaped incision;
           - transverse limb:
                 - is made at the level of the joint line (or just below it);
                 - posteriorly the incision extends just past the fibular head;
                 - anteriorly the incision extends to the patellar tendon;
           - verticle limb:
                 - extends inferiorly along the lateral crest of the tibia for 10 cm;
    - superiorly, taken care not to injure the patellar tendon;
           - incise thru the patellar paratenon and bluntly spread beneath the tendon;
           - during the osteotomy cuts, a spade retractor can be placed just underneath the patellar tendon for protection;
    - incision is carried down to periosteum, and anterior compartment musculature is elevated off the cortical surface;

- Management of the Fibula:
    - the tibio-fibular joint is disrupted w/ a curved 3/4 inch osteotome;
    - the medial one third of the fibular head may be resected both with the osteotome and and rounguer, which provides better exposure;
    - if the tibiofibular joint has not be disrupted, then exposure of the lateral tibial surface will be suboptimal and closing down the 
           osteotomy will be difficult;
    - once there has been adequate disruption of the tibio-fibular joint, the fibula may be displaced posteriorly which allows a "spade 
          retractor" to pass directly posterior to the tibia which protects the posterior musculature and the neurovascular structures;

- Transverse Osteotomy:
    - guide placed parallel to the joint line:
           - two Kieth needles are inserted at the proximal tibial joint line, front and back, on both the medial and lateral sides;
                  - it is important that the two lateral needles be placed over the central portion of the tibial diaphysis (avoid
                         placing them too anteriorly);
           - transverse osteotomy guide is placed with its top portion touching the needles;
                  - this will position the jig 2 cm below the joint line, note that the jig is positioned correctly when the single 
                         central hole is positioned distally;
           - the jig is tightened down, w/ the medial portion of the jig stabilized w/ soft tissue;
           - drill and then insert one smooth pin into the posterior jig hole, and apply the plate over this construct, and then flex and extend both 
                  the jig and the plate to ensure that they are both parallel to the joint line (matching the patient's own posterior slope);
           - insert a second pin to stabilize the jig;
    - measure the tibial width:
           - drill thru central hole in jig, and measure w/ depth gauge;
    - perform transverse osteotomy:
           - apply curved retractors behind the posterior tibia and just in front of the patellar tendon for protection;
           - saw thru the tibia, from lateral to medial, sparing 10 mm of the medial tibia, ensure that the posterolateral corner is included in the cut;
           - the transverse osteotomy cut should be 2 cm below the joint line;
           - remove the transverse cutting jig;
           - there should be a "green stick" loosness between the proximal and distal fragments, otherwise not enough bone has been cut 
                  (usually the posterolateral corner of the cortex);
    - alternative:
           - some surgeons prefer to make the osteotomy oblique to the joint line so that there is not a significant step off between the 
                   proximal and distal osteotomy segments;
           - consider terminating the osteotomy in a 5-mm diameter hole, drilled in an AP direction, with its center positioned 10 mm from the 
                   medial cortex and 2 cm below the articular surface;
           - ref: Avoidance of medial cortical fracture in high tibial osteotomy: improved technique.

- Perform Oblique Osteotomy:
    - apply the oblique osteotomy jig over the guide pins;
    - the thin tongue of the jig is inserted into the transverse ostetomy site;
    - selected the appropriate osteotomy angle, and make the cut so that the saw blade intersects the previous cut;
    - the wedge of bone is removed;

- Close Down the Osteotomy:
    - apply the L shaped plate over the smooth pins;
    - replace the pins (one at a time w/ 6.5 mm screws), but do not tighten them down all the way;
    - apply the drill aligner into the two distal holes, and make a single cortex 3.2 mm hole in line 
          w/ the distal plate;
    - place the compression clamp thru the single cortical hole and around the plate;
    - using the compression clamp apply slow constant compression across the osteotomy;
           - note: if the original transverse osteotomy cut spared too much bone, then closing down of 
                   osteotomy risks creating a tibial plateau frx;

- Secure the Plate:
    - apply and tighten down the cortical screws;
    - revisit the proximal cancellous screws;

- Radiographic Confirmation of Correction:
    - recognize that in the supine position, that the leg may lie in more valgus than it would in the 
           standing position (due to ligamentous laxity);
    - consider obtaining an intraoperative varus stress view;
           - if the valgus position is maintained, then an adequate osteotomy has be performed



High tibial osteotomy. Use of an osteotomy jig, rigid fixation, and early motion versus conventional surgical technique and cast immobilization.

Avoidance of medial cortical fracture in high tibial osteotomy: improved technique