Our hips are comprised of ball and socket joints which means a joint with a round head fits snugly into a cavity, allowing the joint to move more freely. The hips are weight bearing joints and are used all day for standing, walking, running, sitting, and other activities. It should be no surprise that the cartilage (the cushion in between the joints) in our hips wear down quicker than in other joints, mostly due to time, wear and tear, and repetitive motion.
When the cartilage wears down, muscles and tendons can become overused, and the hip pain begins. Hip replacements are becoming common, especially in older patients. In the U.S. alone, there were 332,000 total hip replacements in 2010. Science and medicine have made great strides in hip replacements. What used to be a 9 day hospital stay, 20 years ago, is now a 3-4 day stay. While most replacements occur in those between the ages of 50 and 80, there is no age limit for the surgery.
There are three kinds of hip replacement techniques: cemented, cementless and a hybrid. A total hip replacement requires an artificial hip, or prosthesis, to replace the damaged one. This implant is made with plastic and metal. Orthopedic surgeons use cement to secure the prosthesis into place. Cemented hip replacements are usually reserved for older patients with weaker bones and who do not lead a very active lifestyle.
A cementless hip replacement uses a prosthesis that is porous, and allows the bone that is already there to grow into the microscopic areas. This allows the patient’s own bones to hold the replacement in place. This is usually a better choice for the younger patient who has stronger bones and leads a more active lifestyle. A hybrid replacement is a combination where only a part of the prosthesis is fixed with cement.
These replacements have similar end results, and the new hips can last from 15 to 20 years. Younger patients who move around may find their replacements wear down faster, however, and could be candidates for revision surgery.
Even though cementless hip replacements are usually for those with stronger bones, older patients can be eligible for the surgery. A study in Finland, however, showed that those between the ages of 80-89 have a high early failure rate with this type of surgery. Between 1998 and 2009 there were 4,509 octogenarian patients given a cementless hip replacement. Within one year, a revision was necessary, mostly for women, for more than twice the amount of patients receiving the cementless replacement as opposed to those having a cemented hip replacement. The main cause was a periprosthetic fracture, which is a break around the implant, and is a serious complication.
This study also showed that patient’s with a cementless replacement had a slightly lower 10 year survival rate compared with those that had a cement or hybrid replacement. Time and studies will show if this trend continues.