Cementless Surgery

Modern total hip replacement was developed in England in the 1950’s by Sir John Charnley. He is credited with two ideas that made hip replacement a successful procedure. One was the use of a “low friction” bearing surface of polyethylene against which the metal ball could articulate, and the other was the use of acrylic cement (polymethylmethacrylate) to anchor the implants to bone. Although he didn’t know why at the time, he always warned about doing this surgery in younger active adults because they would fail earlier as compared those in older inactive patients.

In 1968 the first total hip replacement was done in the US using Charnley’s method and materials. The initial results were very successful, but with time in the late 1970’s some implants were failing, especially in younger more active patients (just as Charnley had predicted). After careful analysis several researchers determined that cement was the “weak link”. It was subject to fatigue cracking and that was felt to be the reason for failure in the more active patients. Some called the destruction of bone around the implants “cement disease”. In the 1980’s the concept of “cementless” fixation of implants to bone was perfected and by the 1990’s they were commonly used in the younger more active patients.

In the late 1990’s we were all surprised that these new cementless implants were also failing early in younger active patients …just as the cemented ones had, It turns out that the main reason for failure was that the small wear particles of the polyethylene bearing surface were causing a reaction around the implants, resulting in the destruction of bone (now termed by some as “particulate disease”) which is termed “osteolysis”. It is now felt that the cracking of the cement was secondary to this destructive process, causing the cement to no longer having the support of the surrounding bone.

Today we have better polyethylene (“highly cross-linked”) as well as alternative bearings of metal–on-metal and ceramic-on-ceramic, that have significantly reduced the wear particles generated. Therefore, with the new bearings (which began clinical use in the US in ~2000), whether a hip implant is put in with or without cement most likely will not affect the longevity of the implant. We usually make the decision of whether to use cement or not based on the patient’s bone quality as reflected by how much osteoporosis the patient has, rather than based on age or activity.