Treatment of tibial defect

Treatment of tibial defect

Bone defect could be encountered in primary TKA, although which is more common in revision procedure. In most primary TKA cases, bone defect usually occurs on the tibial side, which can be solved by the following ways:

1. Lateral displacement

Use a smaller tibial prosthesis and place it laterally (Fig. 1), meantime the tibial tray should be as large as possible in terms of the intact tibial area, so as to obtain the best contact and stress distribution.

2. Increase tibial osteotomy

When there is an asymmetric defect at the proximal tibial, it is better to perform the osteotomy in the normal level rather than downward too much. (Fig. 2)

3. Cement filling

Small defect less than 5 mm is usually filled with bone cement. In order to increase the contact area and reduce the shear force that cement may bear, it is recommended to use the methods of cement filling after trapezoidal osteotomy introduced by Krackow. (Fig. 3)

4. Bone graft

Bone grafting is more suitable for bone defect between 5 and 10 mm. Insall described the embedded autogenous bone grafting technique, which converted the disc-shaped peripheral bone defect into trapezoidal shape, thus providing close contact conditions for the trimmed bone graft. (Fig. 4) Because of the internal locking mechanism, this technique does not require additional fixation.

5. Wedge-shaped augment and prostheses with stem extension 

For bone defects larger than 10 mm, wedge-shaped augment and prostheses with stem extension can provide the most effective fixation and optimal stress conduction. The advantage of wedge-shaped augment is that it does not need to be integrated onto the host bone, nor does it pose the risk of bone nonunion and collapse. When the strength of the support bone below the prosthesis is insufficient, extension stem should be considered to disperse the stress on the supporting surface below the prosthesis. Brooks et al. have shown that tibial stem extension can bear about 30% of body weight when its length exceeds 70 mm.

SKII PS high flexion total knee system, the same platform design, can be used either for normal primary TKA or primary TKA case with tibial bone defect with stem extension and tibial augment.