Hip and Knee Replacement Together: What Should You Know Before Surgery?

When arthritis or long-term wear affects both your hip and your knee, it can be hard to tell where the discomfort comes from. You might limp to protect one joint and put too much load on the other. Over time, this way of compensating can make both joints wear out faster. It can also leave you unsure which one is causing the most trouble.

It helps to understand how the two joints affect each other, and how they link to your spine, pelvis and leg alignment. This helps you and your surgical team make better decisions about timing, the order of operations and implant position.

What are the signs you might need both a hip and knee replacement?

The most common sign is persistent pain in both joints that limits your daily activities. This includes walking, climbing stairs or getting in and out of a car. You may also notice stiffness that does not ease with rest or medicine.

Should I have hip and knee replacement at the same time or separately?

This depends on your overall health, your surgeon's assessment and how badly both joints are affected. There are two broad approaches. Staged means separate operations weeks or months apart. Simultaneous means both joints are replaced in a single surgical session.

Staged replacement is more common. Your surgeon replaces the worst joint first. You then recover and do your rehabilitation, and the second operation is scheduled after that. This spreads out the physical stress and lets your body heal between operations.

Simultaneous replacement means one anaesthetic, one hospital stay and one rehabilitation period. It can suit people who are otherwise fit and whose joints are equally affected. However, it carries higher surgical risk and is not suitable for everyone.

Either way, the order in which the joints are replaced matters. Surgeons often choose based on which joint is more damaged, but alignment plays a crucial role too. A poorly aligned hip can change the angle at which your knee bears weight. So replacing the knee first without understanding the hip alignment could lead to less-than-ideal outcomes.

Why does whole-body alignment matter before joint replacement?

Whole-body alignment matters because your hip, knee, ankle and spine work as a connected chain. A change in one part shifts how every other part bears load. If your surgeon only sees one joint on its own, they may miss the bigger picture. That bigger picture affects implant position and how well the joint works in the long term.

When you stand, gravity pulls through your body in a specific pattern. If your pelvis tilts, your thigh bone sits at a different angle. This changes the forces through your knee. If your knee is already arthritic and stiff, it pushes extra strain back up to the hip and down to the ankle.

Most standard imaging, such as X-rays, CT or MRI, is done while you lie down. In that position, your muscles relax and your joints settle differently than when you are upright and bearing your own weight. This means lying-down scans can underestimate or miss the misalignment that causes your symptoms during everyday activities like walking and standing.

How does an EOS scan help plan a hip and knee replacement?

An EOS scan captures your entire skeleton from head to feet in a single standing image. This gives your surgeon a true weight-bearing view of how your hip, knee, pelvis, spine and ankles relate to one another under gravity.

Because you stand for the scan, it shows the real alignment your body uses every day. Your surgeon can see whether your pelvis tilts, whether one leg is longer than the other, and how your knee and hip angles affect each other. All of this helps them plan implant size, angle and position more precisely.

EOS also uses about 90% less radiation than a standard X-ray, around ten times less. That lower dose is especially useful when you need several scans during planning, the check-up before surgery and the follow-up after surgery.

To learn more about how EOS standing imaging works and what it involves, visit the EOS scan overview.

Who should consider standing alignment imaging before double joint replacement?

Anyone facing hip and knee replacement on the same side, or even on different sides, can benefit from understanding their full alignment before surgery. It is especially relevant if earlier scans have not fully explained your symptoms, or if your surgeon wants to plan implant position carefully.

For details on knee alignment imaging, including what the scan covers and how it helps surgical planning, see our knee page.

Before you start treatment, or change the one you are on, it is worth getting a detailed diagnosis. Knowing whether the cause sits in your pelvis, your legs or your spine changes what will actually help.

Frequently asked questions