Knee replacement surgery alignment and balancing techniques

Knee replacement surgery aims to relieve pain and restore function in people with severe knee arthritis. For the best long-term results, accurate alignment and soft tissue balance are essential. Advances in surgical technique and implant design, including the use of medial stabilised inserts, have helped improve the stability and natural movement of the knee following surgery.

Why is alignment important in knee replacement surgery?

The alignment of the knee joint refers to how the bones and components fit together. Poor alignment after surgery can lead to uneven wear of the implant, pain, instability or even early failure of the replacement. Correct alignment ensures:

Even load distribution across the joint
Better function during walking and other activities
Reduced wear on the implant
A more natural feeling knee

Surgeons use various techniques and technologies — such as mechanical guides, computer navigation or robotic systems — to achieve precise alignment during the operation.

What is knee balancing, and why does it matter?

Balancing refers to adjusting the soft tissues (ligaments and tendons) around the knee so that the joint is stable throughout its range of motion. Imbalance can cause stiffness, instability or discomfort after surgery.

The surgeon will assess and adjust:

Flexion and extension gaps (space in the knee when bent and straight)
Tension in the ligaments on either side of the knee
Rotational alignment of the femoral and tibial components

Careful balancing ensures that the knee moves smoothly and feels secure, particularly when walking or climbing stairs.

What are medial stabilised inserts, and when are they used?

Medial stabilised inserts are a type of polyethylene insert used in knee replacement implants. They are designed to replicate the natural movement of the knee more closely than traditional inserts.

These inserts:

Provide a stable pivot point on the inner (medial) side of the knee
Allow controlled movement on the outer (lateral) side, mimicking natural knee kinematics
Improve stability in both flexion and extension
Help reduce reliance on the patient’s own soft tissue structures

Medial stabilised inserts are especially helpful in cases where ligament function may be reduced or when the surgeon wants to ensure greater mid-range stability. They can be used in both total and partial knee replacement procedures.

Key benefits of accurate alignment, balancing, and implant choice

Improved joint function and stability
Reduced risk of postoperative complications like dislocation or loosening
Better long-term outcomes and implant survival
More natural movement of the knee joint
Enhanced patient satisfaction and return to daily activities

Is this approach suitable for all knee replacement patients?

Modern alignment and balancing techniques, along with the option of using medial stabilised inserts, are suitable for most patients undergoing total knee replacement. However, individual anatomy, bone quality and ligament condition will influence the choice of implants and surgical technique.

A consultant orthopaedic surgeon will evaluate your specific needs and recommend the best approach. Accurate alignment, effective soft tissue balancing and appropriate implant design work together to deliver a stable, functional knee joint with lasting results.