Why I use the curved lateral incision for knee replacement surgery

A small decision that matters more than it looks

When most people think about knee replacement surgery, they think about the implant — the metal and plastic components that replace a worn joint. What they rarely think about is the skin incision: the cut that gives the surgeon access in the first place. It seems like a minor detail. In practice, it is anything but.

Since 2024 I have been using a curved lateral skin incision for knee replacement surgery — both total and partial knee replacements — rather than the traditional straight midline incision. This article explains what that means, why I made the change, and what it means for patients.

The traditional approach: a straight midline incision

For decades, the standard skin incision for knee replacement has been a straight vertical cut directly down the middle of the front of the knee. It is a reliable approach that surgeons have used for generations, and it works well. Most knee replacements worldwide are still performed through a midline incision, and there is nothing wrong with that.

The midline incision runs directly over the patella (kneecap) and the tibial tuberosity — the bony prominence just below the knee. Because the scar sits over these bony landmarks, it is exposed to pressure whenever the patient kneels. Over time, many patients describe discomfort or numbness directly over the scar, particularly when kneeling on a hard surface.

What is the curved lateral incision?

The curved lateral incision is an alternative that sweeps slightly to the outside (lateral side) of the knee, curving away from the midline rather than running straight down it. The internal approach to the joint remains the same — the implant is prepared and inserted in exactly the same way. What changes is only the path the skin incision takes.

By moving the scar away from the midline bony prominences, the incision avoids sitting directly over the tibial tuberosity and the central portion of the patella. The practical result is that the healed scar is less likely to be directly in the firing line when a patient kneels.

The implant is the same. The internal approach is the same. What changes is where the scar ends up — and for patients who want to kneel comfortably again, that matters.

Why I made the change in 2024

The decision came down to a straightforward observation from patient feedback over time. Knee replacement works extremely well at relieving pain and restoring function for walking, stairs, and everyday activity. But kneeling — whether for gardening, getting in and out of a low car, playing with grandchildren, or prayer — remained a common source of discomfort even in otherwise successful cases. A significant part of that discomfort was scar-related rather than joint-related.

The curved lateral incision is not a new idea. It has been described in the orthopaedic literature and used by various surgeons for some years. What took time was accumulating enough confidence in the exposure it provides and its reliability in a range of patient anatomies before adopting it as my standard approach. By 2024 I was satisfied it offered a genuine benefit without any meaningful trade-off in surgical access or outcomes.

It is also worth noting that this incision works well alongside the MAKO robotic system. Because the robotic approach is highly precise and planned in advance from a CT scan, the bone cuts and implant positioning are not dependent on a particular skin entry point. The robotic arm works within a pre-planned boundary regardless of where the skin incision sits, which means the two approaches are fully compatible.

What it means for patients

For the vast majority of patients, the surgical experience and recovery are the same as a standard knee replacement. The operation takes the same amount of time, the rehabilitation is identical, and the implant being used is unchanged.

The potential benefit is in the long term: a scar that sits off the bony midline is less likely to cause discomfort when kneeling. For patients who are younger and active, or whose lifestyle or work involves kneeling, this is a meaningful consideration. For patients who are older and less likely to kneel regularly, it is a smaller advantage — but still not a disadvantage.

It is important to be clear that no incision technique eliminates all scar-related symptoms. Some patients will still experience numbness or sensitivity around the scar regardless of its position — this is a normal part of healing after any knee surgery. The goal of the curved lateral approach is to reduce the likelihood of the scar being a source of ongoing discomfort, not to guarantee it will not be.

Not for every case

There are situations where the curved lateral incision is not the right choice. Patients with pre-existing scars from previous knee surgery may require a different approach — crossing or cutting across an old scar carries a risk of wound healing problems, so the incision often needs to follow the original scar line. In revision surgery, where previous incisions must be respected and tissue planes may be altered, the standard approach may be necessary.

Each case is assessed individually at consultation. The choice of incision is one part of the overall surgical plan, and the right choice depends on the patient’s anatomy, history, and goals.

The bigger picture

Knee replacement is one of the most effective operations in medicine. The core goal — relieving pain and restoring function — is well established. What continues to evolve is the fine detail of how the operation is done: the tools used, the precision achieved, and the smaller decisions that add up to a better experience for the patient.

Switching to the curved lateral incision is one of those smaller decisions. It does not change what the operation is. It changes where the scar ends up — and for patients who want to kneel comfortably again, that is worth doing.

If you have questions about knee replacement surgery and what approach would be most appropriate for you, I am happy to discuss this at your consultation.