A number of chronic diseases are associated with cartilage or bone degradation: Arthritis is caused by the wearing away of cartilage from either overuse injuries or immune attacks on the joints, leaving the bones to rub against one another and cause pain and stiffness while other conditions, like Marfan syndrome, are associated with lower bone density, which can make skeletal injuries more likely to occur. With this degradation there is often increased daily pain and decreased mobility, which can serve to make other symptoms worse by discouraging exercise or affecting sleep.

Degenerative diseases can cause the breakdown of skeletal tissue, decreasing mobility and causing pain

While older implants and replacements have generally used metals for their great strength and durability, these carry unique risks like toxicity due to corrosion of the implant releasing debris into the bloodstream. Local adverse reactions are not uncommon, and some people are even allergic to metals, although this is very rare. With these issues, and a desire to prevent degradation of surrounding bone that is associated with high molecular weight plastic alternatives, new implants are increasingly based in ceramics.

While old ceramics implants faced significant failure rates due to design issues, new ceramics have shown great promise and wide applications. Ceramics are currently readily used for joint replacements because of their great durability, which is ideal for allowing patients to return to activity and for long-lasting solutions for younger patients, as for those suffering from chronic conditions, rather than elderly populations dealing with age-related bone and cartilage degradation. With ceramic-on-ceramic hip replacements, nearly all patients in one study reported being able to participate in daily physical activities, and every patient in the study demonstrated osseointegration with no complications like implant loosening or implant-related bone loss in follow-up appointments. Perhaps surprisingly, ceramic-on-ceramic joint replacements were shown to have significantly lower wear rates than metal-on-plastic or metal-on-metal replacements, showing that durability is no issue for these new implants either.

Ceramics have miniscule levels of surface erosion and debris release

One major issue with ceramics for joint replacements, however, is squeaking of the joint, which can make patients uncomfortable and in some cases lead them to get additional surgeries to correct the problem. This happens when edge-loading causes increased friction and wear, leading the implant to lose its seal on the corresponding socket. In some cases, the ceramic liner itself fractures, causing both squeaking and sharp pain for patients. Revision surgery is much more complicated and likely to lead to complications, so it should be avoided if at all possible to preserve mobility and prevent ongoing pain issues. To solve this, some researchers have suggested making this socket liner thicker to prevent seal loss or in some causes, altering the material or shape of the implant to reduce the resonance of the sound coming from the joint.

Various causes of joint replacement squeaking

While the material itself is ideal, with little degradation and great biocompatibility and integration, the design behind ceramic-on-ceramic implants needs ongoing development to maintain its integrity to provide an increasingly successful long-term implant for younger and more active patients.

Sources:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5247519/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4976577/