Not long ago, 54-year-old Brij Kishore could barely walk without excruciating pain. He had advanced osteoarthritis with deformities in both knees and was relying on family members to move even small distances.
Now, thanks to a knee replacement using a cementless titanium implant, Kishore is back on his feet and looking forward to walking again without pain. His case – reported by India Today: Cementless robotic knee surgery could be a game-changer for arthritis – throws a timely spotlight on cementless knee replacement, a technique that encourages the joint bones to grow into the implant, rather than fixing it in place with cement, the traditional, ‘gold standard’ approach to TKA (total knee replacement).
But how exactly does cementless versus cemented knee replacement actually work? And if you’re thinking about knee replacement yourself, should you consider it?
Is this a new technology?
Actually, no, it’s not. Cementless knee replacements (also called biologic fixation or press-fit implants) have been around for several decades. In fact the implants have long been popular in Australia, where Mr Bailey did his fellowship training in the 2000s. Here in the UK, particularly in the NHS, they’re less common. But that may be set to change. In America, for instance, one study discovered a 240% rise in the proportion of knee replacements using cementless implants between 2015 and 2021. That suggests more surgeons are adopting the technique, and that more patients are considering it as an option.
Cemented vs cementless knee replacement: what’s the difference?
Artificial knees need a strong, stable connection with the bones either side of the implant (the femur and tibia). The traditional way to do this is with a special medical-grade cement, typically polymethyl methacrylate (PMMA). Once applied, it takes about 10 minutes to set and create a firm fixation. In a cementless replacement, there’s no fixing material. Instead, the implant has a porous or textured surface. The idea is that your bone will grow into this textured surface over time, creating a natural fixation.
What are the advantages of cementless knee replacement?
There are several potential benefits:
- Biological integration – because it relies on your own bone to hold the implant in place, a cementless replacement has the potential to create a more natural, “biologic” bond
- Long-term durability – though the traditional cement is well attested and highly effective, it can deteriorate over a long period of time or with high-impact activity; this can lead to loosening of the implant
- Bone preservation – the cementless approach preserves more of your natural bone than the traditional procedure
- Reduced surgery time – studies show cementless procedures need less time in the operating theatre (largely because of the setting time required in cemented surgery)
It’s worth adding that cementless knee replacements require high-precision surgical cuts to ensure optimum fixation for the implant, which is one reason why they’re often performed with robot-assisted surgery (like Kishore’s operation, above).
What are the risks or drawbacks of cementless replacements?
You might be asking: if “press-fit” implants are so good, why doesn’t everyone have them? The main reason is that, to be effective, cementless implants need good existing bone to enable a firm fixation: that is, bone that’s healthy and porous enough to bond with the textured implant. This means they’re not recommended for people with bones that are weaker or have poor density (for instance, through osteoporosis). There’s also the cost factor; cementless replacements are more expensive than the traditional procedure. Finally, there’s the fact that high-quality long-term data for cementless implants is still quite limited. We need more studies (and time) to be certain of the long-term advantages.
Could I be a good candidate for cementless knee replacement?
With all that said, we do recommend cementless implants for certain patients. In fact we use the procedure regularly here at Chris Bailey Orthopaedics when we feel it would most benefit the patient. So who is a good candidate for cementless? Broadly speaking, it’s best for:
- More active patients – people who, being likely to put strain on their new knees, will need a long-lasting fixation
- Good bone density – patients whose joints will provide the strongest anchor for the implant
- Younger patients – in simple terms, younger bones are more metabolically active and better able to grow into the porous surface of the implant, creating a stronger biological bond (the average age for cementless replacements is around 63, versus 68 for cemented).
The final word: cementless or cemented?
There’s no doubt that cementless knee replacements are a good choice for the right patients – and, with the rise in take-up for cementless, the technology that goes into these implants is only going to get better with time. But the key phrase is “the right patients”. The cementless implant isn’t a one-size-fits-all solution. So while it can offer excellent results for some, for others the traditional, “gold-standard” cemented procedure will be the better approach. Talking with your orthopaedic surgeon about your age, history, bone health and activity levels will help them to determine the best route for you. On which note, here are some questions that it may be helpful to ask at your appointment:
Cementless knee replacement checklist: What to ask your surgeon
- Do you perform cementless replacements regularly?
- Does my age make me a better candidate for one approach over the other?
- Would my bone quality support it?
- How would you determine that?
- How long will my recovery take compared to a cemented replacement?
- What activity restrictions will I have during the bone integration period?
- Will I need any special monitoring to ensure the bone is growing into the implant properly?
- What are the cost differences between cementless and cemented replacement?
