Robotics in Hip Replacement

The Ball and Socket Joint

The hip joint is made up of two major bones: the pelvis (which contains the acetabulum—the socket) and the femur (the thigh bone, with its head forming the ball).

Around these bones are ligaments, capsular attachments, and multiple muscles that cross both joints, giving the hip power and motion. As a ball and socket joint, it can rotate, flex, and extend with nearly 360 degrees of range of motion.

The Labrum & Cartilage

The acetabulum (socket) is lined with hyaline cartilage—a smooth lining—and the femoral head is similarly covered. Around these surfaces is the labrum, which acts like a meniscus in the hip.

The labrum is a bumper of cartilage that helps create a better suction fit of the femoral head and disperses contact pressures between the two bones.

What Is Osteoarthritis?

Osteoarthritis is the degradation of cartilage. Like the Teflon on a pan or tires on a car, cartilage experiences wear and tear over time. It can degrade traumatically or through repeated injections, trauma, or infection.

When cartilage degrades, pits and crevices form where joint fluid gets pushed into the bone. This can lead to cracks and insufficiency fractures, causing the hip to flatten. The joint loses its perfect symmetry, leading to increased contact pressures and more wear—until moving becomes very painful.

What Causes Hip Arthritis?

Anything that increases pressure or decreases motion can predispose you to degenerative changes:

• Dysplasia — Being born with a hip that's not perfectly formed, even a few degrees or millimeters off
• Micro-instability — Repetitive labral tears, hip dislocations that cause wear earlier
• Childhood infections in the hip
• High-impact sports — Squash, hockey, basketball (deep hip flexion, explosive jumping)
• Genetic predisposition — If your mom or sister had hip replacements, you may be more likely to need one

The Clinical Examination

The exam starts by watching how you walk—using a cane, limping, shortened strides. Then how you transfer from seat to exam table, how you lie down.

Hip pain classically presents in the groin, but can also appear as buttock, thigh, or even knee pain. Hip flexion and internal rotation causing exacerbation of symptoms is the classic sign of hip osteoarthritis.

If there's uncertainty, diagnostic injections (freezing injected into the joint under ultrasound) can confirm whether the hip is the pain generator.

Pre-Operative Planning

Most hip surgeons template with X-rays and a calibration ball. Now, CT scans provide more detail for better implant templating.

The execution of that plan traditionally relied on human assessment and crude technique. With robotics, cup positioning, anteversion, inclination—all can be dialed to the degree and millimeter.

The Surgeon Still Drives

All current orthopedic robotics are assistive technologies. The surgeon makes decisions and executes the surgical plan manually with the technology's help.

Some say robotics isn't needed because hip replacement already has excellent outcomes. But anything that makes the surgeon more confident and more accurate shouldn't be dismissed. It's about taking 95%+ good-to-excellent results and pushing even higher.

Adoption Rates

In the US, over 60% of the American Hip and Knee Society use the anterior approach. In Canada, it's about 15%, but demand is pushing more surgeons to change their practice.

The technique was originally described in France over 100 years ago but is perceived as "new" because it's only recently become widely adopted.

Day of Surgery

You'll meet anesthesiologists and nurses, get IVs, and likely receive a spinal anesthetic with possible nerve blocks. You're then brought to the OR and placed on the HANA table—a specialized tool that facilitates anterior hip replacement surgery.

Pins may be placed into the bone to allow for navigation. Bony landmarks are registered and compared to the surgical plan.

The Operation

Through the front, between muscle layers, the surgeon:

• Resects (removes) the femoral head—the ball portion
• Reams the acetabulum (socket) to prepare for a press-fit metal cup that bone grows into
• Places a plastic liner inside the cup—your new cartilage
• Prepares the femur with broaches, then places the femoral stem
• Trials different head sizes and lengths to customize the fit
• Checks robotic calibration and AI feedback on the positioning

Companies offer up to 24 different stem sizes and various offsets and neck angles for customization.

How Long Does It Take?

Originally 3.5-4 hours, modern hip replacement surgery now takes 35-45 minutes. Better instruments, better tools, and better understanding have made the operation smaller, simpler, and with better results.

Changed Expectations

Patients used to be happy just walking without a cane. Now they ask: "When can I go heli-skiing? When can I do Pilates or jiu-jitsu?"

Patients are cycling 100 kilometers on weekends at 4 weeks post-op. Expectations have risen, and every improvement in technique helps meet those expectations.

Myth: "Arthritis is part of aging—you have to live with it"

Partially true, but... While degenerative changes are natural, that doesn't mean you can't treat the consequences. If you're having pain, can't do what you want, and nothing else helps—there are good surgical and non-surgical options.

Myth: "A hip replacement won't feel natural"

False. Most patients can't even tell which side was operated on. Done well, it will 100% feel natural.

Myth: "Severe arthritis means you can't get a hip replacement"

False. If you're fit enough for surgery, you're likely a candidate. Deconditioned patients may take longer to recover, but severe X-ray findings alone don't disqualify you. The decision depends on your overall physiological health.