Could a Cementless Knee Replacement Benefit Patients? Early Results of Our HSS Study

Cementless knee replacement, an alternative to traditional cemented knee replacement surgery, is gaining interest in the field of orthopedic surgery. We launched a study at Hospital for Special Surgery (HSS) to compare outcomes of a modern cementless knee implant to the standard knee implant that requires bone cement for fixation. 

Our study found no difference in hospital length of stay, complications, hospital readmission within 90 days of surgery, or rates of revision surgery at two-year patient follow-up. We presented our research at the American Academy of Orthopaedic Surgeons 2022 Annual Meeting in Chicago. 


With respect to time spent in the operating room (OR), using the cementless implant reduced OR time by 25%, saving an average of 27 minutes. In a cementless total knee replacement, you do not have to wait for the cement to harden and dry like you do in a cemented knee replacement, which saves time. 

Reduced time in the OR under anesthesia is advantageous to patients, but that's not the only potential benefit of the uncemented prosthesis. With the cementless knee replacement, the components are press fit into place for ‘biologic fixation,’ which basically means the bone will grow into the implant. If there is initial biologic fixation, implant loosening over time should be less likely and a total knee replacement could potentially last much longer.

In a traditional knee replacement, implant components are secured in the joint using bone cement. It’s a tried-and-true technique that has worked well for decades. But eventually, over time, the cement starts to loosen from the bone and/or the implant. When it wears out or loosens, patients generally need a second knee replacement, known as a revision surgery. The cemented knee implant used in a traditional joint replacement usually lasts 15 to 20 years. 

A well-designed cementless implant could make loosening over time less likely, enabling a total knee replacement to last much longer. Implant longevity is an important consideration, especially for younger patients with arthritis who opt for joint replacement to maintain their active lifestyle. They generally put more demands on their joint, causing more wear and tear and potential loosening. 

Cementless implants have been used successfully in total hip replacement surgery for many years. It has been much more challenging to develop a cementless prosthesis that would work well in the knee because of the knee’s particular anatomy.

In the past, a number of cementless knee implants were shown to have design flaws, with loosening from the shin bone. In our study, we used a newer cementless prosthesis that not demonstrate this type of loosening in previous published studies. We set out to see how the implant fared in HSS patients.

We reviewed 598 primary unilateral total knee replacements at HSS (170 cementless and 428 cemented) of the same design from 2016 to 2018. Patients undergoing the cementless procedure were younger overall, with a mean age of 63, versus 68 for those having a traditional cemented knee replacement. Good bone quality is important in the success of cementless knee fixation. 

There was no statistically significant difference in hospital length of stay, complications, or hospital readmission for a problem in the first 90 days after surgery. Ninety-six percent of cementless knee replacement patients versus 95% of those with a cemented knee replacement maintained their implant without the need for revision surgery at two-year follow-up. 

More studies are needed to look at longer-term patient outcomes and implant durability. For more information, visit WestrichMD.com

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