PHYSICA ZUK SURGICAL TECHNIQUE Step 7 | Performing Trial Reduction
To insert the Tibial Trial Liner on the already placed Tibial Trial Plate, slide the rails on the bottom of the Tibial Trial Liner into the grooves on the Tibial Trial Plate. (Fig. 55) Check the fit of the components. If the bone cuts are not flush, use the rasp to provide minor changes to the bony surfaces. With all trial components in place, check the range of motion and ligament stability. The Tibial Trial Liner should allow for full flexion and full extension.
NOTE. Overstuffing should be avoided, as this will overload the contralateral compartment.
Figure 55
The correct thickness of the final liner is one that provides the desired alignment and dœs not cause excessive stress on the collateral ligaments. As a rule, the correct thickness of the liner should allow the joint space to be opened approximately 2 mm when a stress is applied, with the knee in full extension and without soft tissue release. The knee must also be tested in 90° of flexion to allow a 2 mm flexion gap. Excessive flexion tightness will prevent postoperative flexion and may cause the tibial prosthesis to lift up anteriorly as the femoral component rolls posteriorly on the tibial component. If the joint is too tight in flexion, or extension, review the options described for the extension/ flexion gap (check step 3, p. 16). TECHNIQUE TIP. Use the 2 mm end of the Tension Gauge to check the balance of the knee in both flexion and extension. With the knee flexed 90°, position the 2 mm end of the Tension Gauge between the Femoral Trial and the Flexion/ Extension Gap Spacer. This should be a snug fit but not overly tight. Then perform the same test with the knee in full extension. (Fig. 56) If the 3 mm end of the Tension Gauge can be inserted easily, then the knee may be too loose and a thicker tibial liner may be considered.
Figure 56
28 Surgical Technique PHYSICA ZUK
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