Why I Use the Subvastus Approach for Knee Replacement

Your quadriceps is the engine that gets you out of a chair and up the stairs. When I replace a knee, I go out of my way not to cut into it.

By Dr. Luc Rubinger, MD, MBA, FRCSC · Orthopaedic surgeon, hip & knee replacement · Durham Bone and Joint Specialists, Ajax · Last reviewed November 2026

The short version

  • The subvastus approach reaches the knee by lifting the quadriceps muscle out of the way from underneath, instead of cutting through its tendon.

  • The quadriceps tendon is left completely intact.

  • Many patients get leg control back sooner and have less pain in the early weeks.

  • Long-term results are similar to the standard approach. The advantage is a better start, and not every knee is suited to it.

How most knee replacements are done

To replace a knee, I need to get the kneecap out of the way so I can reach the ends of the thigh bone and shin bone. The most common way to do that, used by most surgeons worldwide, is an incision along the inner edge of the kneecap that continues up through the quadriceps tendon.

It's reliable and gives an excellent view. The tendon is repaired at the end, but like any repair it has to heal, and in the early weeks it can make the front of the knee sore and the leg feel weak.

Under, not through

Just above the inner side of your knee is a teardrop-shaped muscle called the vastus medialis. It's part of the quadriceps and plays a big role in straightening the knee and keeping the kneecap tracking in its groove.

With the subvastus approach, I lift the lower edge of that muscle and slide it aside to reach the joint. The tendon is never cut. Think of lifting the edge of a rug to get underneath it, rather than cutting a slit down the middle.

Why I choose it

  • Your quadriceps stays intact. One of the first milestones after knee replacement is lifting your leg straight off the bed. With the tendon untouched, many patients manage it sooner.

  • Less early pain. There's no tendon repair healing at the front of the knee, which often makes the first weeks more comfortable.

  • Natural kneecap tracking. The muscle that helps guide your kneecap is left alone, so the mechanism that keeps it running smoothly is preserved.

  • It fits my overall philosophy. Together with kinematic alignment and robotic guidance, the goal is the same: disturb as little of your own knee as possible.

The honest trade-offs

  • It's a tighter space to work in. It takes experience to do well. In very stiff knees, severe deformity, or knees that have had previous surgery, I may use the standard approach. Sometimes that decision is made during the operation, and that's a judgement call made in your interest.

  • The long run evens out. By a year or two after surgery, studies generally show similar function between the approaches. The subvastus approach gives you a head start, not a different finish line.

Common questions

Will my scar look different?

Yes. The skin incision on the front of the knee looks much the same but it will be on a diagonal, not straight down the middle of the knee.

Will I recover faster overall?

Early milestones often come sooner, but a knee replacement still takes months to fully settle, and physiotherapy is still essential. The approach can give you a head start; it can't do your exercises for you.

Is this the same as "minimally invasive" knee replacement?

It belongs to the same family of ideas, often called quadriceps-sparing surgery. The focus is on protecting muscle and tendon rather than simply making a smaller incision.

Can every knee be done this way?

Most of the knees I replace can, but not all. We'll talk about it at your consultation, and I'll be upfront if a standard approach is the safer option for you.

Related reading

Seeing Dr. Rubinger

I see patients at Durham Bone and Joint Specialists in Ajax, with surgery at Lakeridge Health Ajax Pickering Hospital and Schroeder Ambulatory Centre. In Ontario, you'll need a referral from your family doctor or nurse practitioner. Referral and contact information · Knee replacement overview.

This article is general information to help you understand your options. It isn't medical advice for your specific situation. Whether a procedure is right for you depends on an assessment by your surgeon.