Hip replacement devices functions like the anatomic hip joint after it is implanted in the human body. The device comes in various designs and materials depending on its manufacturer. A new line of hip implants, with all metal materials was introduced by DePuy Orthopedics in 2003 but due to high failure rate, a recall was made in 2010. According to reports, Australian Orthopedics expert testifies the evidence that DePuy hip failure existed 3 years before recall. More evidences on metal-on-metal implants causing tissue damage were provided by the New York Times.
The hip or acetabulofemoral joint is found between the femur and the acetabulum of the pelvis which supports the weight of the body. It is a ball-and-socket joint where the head of the femur articulates with the cuplike acetabulum. The ball fits snugly into the concave socket. With strong surrounding ligaments and tight fitting of the bones, the hip joint is a sturdy joint.
In order to duplicate the hip joint’s function, implants have mainly two parts: the ball which takes the place of the femoral head, and the cup which assumes the socket role. In 2003, Johnson & Johnson’s DePuy Orthopedics released an all-metal hip implant. Included in the ASR hip replacement system are the ASR XL Acetabular System and the ASR Hip Resurfacing System. However, the company had to recall the devices after reports show a high failure rate. Faulty design is one of the said causes of failure.
The acetabular cup component of the device is the 1st problem. Reports say that compared to other implants, DePuy ASR’s cup is shallower. It is particularly vulnerable to shedding debris because of its shallow design. Also, when compared to the socket, the femoral head appears to be larger. The femoral head is more exposed because ball and socket components do not perfectly fit. Corrosion at the head of the device has reportedly resulted to flaking off of metal particles which may eventually cause metal toxicity.
The reason for failure of the DePuy hip replacement, as believed by orthopedic specialists, is the design of its cup.Dr. Harlan C. Amstutz, an orthopedic surgeon in LA believed that the design was prone to problems. DePuy Orthopedics knew, according to the creator of the device, Dr. Thomas P. Schmalzreid, that the ASR hip system is more difficult to embed when compared to hip implants of the same kind.
A DePuy hip replacement recall has started a year ago and is still happening right now. An additional surgery may be advised for those patients who have received the faulty device. With this, patients, together with their orthopedic surgeons are advised to carefully consider their options as to what hip device they will use.