**4.4 Implant choice**

Some surgeons consider it inappropriate or almost impossible to preserve the posterior cruciate ligament (PCL) in severe valgus deformities. The use of intramedullary nails and implants with revision concepts is also frequently indicated by some surgeons whenever they are faced with a severe valgus deformity [19]. But what is the logical reasoning that should guide the choice of implant? **Figure 2** shows the algorithm for implant choice in valgus TKAs.

**Figure 2.** *Algorithm for implant choice in valgus TKAs.*

*Total Knee Arthroplasty in Valgus Knee DOI: http://dx.doi.org/10.5772/intechopen.109573*

The choice of implant must be based on the degree of joint instability and the presence of bone defects. Taking into account the Ranawat classification, for Grade I valgus knees (<10° deformity and intact MCL), Cruciate Retaining (CR) implants can be used, with proper bony resections and adequate soft tissue balancing for TKA long-term survival. The advantage of CR implants is the preservation of bone stock and improvement in knee proprioception [5, 6, 20–22].

For grade I or II valgus knees, mild-to-moderate coronal deformity is mild (<20°), and the MCL tension is inadequate, posterior stabilized (PS) implant can be used. In young patients, it is possible to preserve bone stock through the use of ultracongruent polyethylene insert, thus avoiding the resection of a box in the distal femur [7, 23–25].

In the presence of MCL insufficiency or >20° deformity (grade III), a greater constraint implant such as condylar constrained knee (CCK) or hinged implants should be used. CCK implants show good results at 10 years of follow-up, with a survival rate of around 97% [23, 26, 27]. Caution should be taken in younger patients, because it is necessary to remove a larger portion of distal femoral bone to accommodate the femoral box, which decreases the remaining bone stock available for revisions. In the case of elderly patients with severe ligamentous insufficiency and multiplanar instability or major bone defects, a hinged implant should be the choice [19].
