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Posterior-Stabilized Design
One of the most commonly used type of implant in total knee replacement is a posterior-stabilized component. In this design, the cruciate ligaments are removed and parts of the implant substitute for the posterior cruciate ligament (PCL).

The tibial component has a raised surface with an internal post that fits into a special bar (called a cam) in the femoral component. These components work together to do what the PCL does: prevent the thighbone from sliding forward too far on the shinbone when you bend your knee.

• Slightly more constrained prosthesis that requires sacrifice of PCL
• Resection of PCL increases the flexion gap in relationship to extension gap so posterior must be matched to avoid flexion-extension mismatch
• Femoral component contains a cam that engages the tibial polyethylene post during flexion
• Polyethylene inserts are more congruent, or deeply “dished”

Indications
• Previous patellectomy
• Reduces risk of potential anteroposterior instability in setting of a weak extensor mechanism
• Inflammatory arthritis
• Inflammatory arthritis may lead to late PCL rupture
• Deficient or absent PCL

Radiographs
Lateral radiograph will show the outline of the cam, or box, in the femoral component

Advantages
• Easier to balance a knee with absent PCL
• Arguably more range of motion
• Easier surgical exposure

Disadvantages
• Cam jump mechanism with loose flexion gap, or in hyperextension, the cam can rotate over the post and dislocate treatment initial closed reduction by performing an anterior drawer maneuver final revision to address loose flexion gap
• Tibial post polyethylene wear
• Patellar “clunk” syndrome mechanism scar tissue gets caught in box as knee moves into extension treatment arthroscopic versus open resection of scar tissue
• Additional bone is cut from distal femur to balance extension gap