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In addition to the risks associated with any type of surgery, hip replacement, though generally very safe, is not without unique complications. Some complications are minor, while some may require additional surgeries or even a new implant to correct. As hip implant technology improves, many of these problems are becoming less and less common, particularly the more catastrophic side effects that cause implant failure. However, they are all still possible. Some types of prostheses, particularly metal-on-metal hip implants, are more vulnerable than others, and several models of metal-on-metal hip replacement have been recalled as a result.
Debris and Osteolysis
During normal motion of a hip implant’s ball-and-socket joint, friction can cause implant material to wear away, releasing small particles of plastic or metal into the area surrounding the device. The cement used to fix implants to the patient’s bones can do the same. This action, though unavoidable, has serious potential side effects that can ultimately lead to implant failure.
The immune system’s response to the debris is to act to eliminate the foreign matter. The mechanism involves immune cells called macrophages that seek out and bind themselves to harmful particles, then absorb the particles and break them down chemically. This is an entirely normal part of the human body’s immune response, but under certain circumstances it can lead to serious complications.
If the immune response is strong enough, it can break down healthy bone in the area around the implant, a process known as osteolysis. This causes painful inflammation, and the loss of bone can lead to a loosening and failure of the implant, making revision surgery necessary.
There is some evidence that cementless implants may be more prone to osteolysis than cemented or hybrid implants.
The aggressiveness of the body’s immune response is dependent on a number of factors, among them the size, composition, and concentration of the foreign particles as well as implant’s rate of wear. Generally speaking, the smaller, more difficult to break down, more highly concentrated and more quickly released the debris, the more aggressively the immune system attacks. There is some evidence that cementless implants may be more prone to osteolysis than cemented or hybrid implants.
While significant advances have been made in implant materials in recent years, physicians are predicting a wave of osteolysis-related revision surgeries in the near future as older hip implants experience age-related wear and tear. Osteolysis is the most common cause of hip implant failure.
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Metallosis and Metal-on-Metal Implants
Metal-on-Metal Implants and Metallosis
Metal-on-metal hip implants, though marketed as more durable than traditional metal-on-polyethylene implants, are particularly prone to debris-related complications and failure. One major problem with metal-on-metal hip implants is that it is impossible to predict how patients will react to the metal debris released into their body.
Metal debris can cause a condition known as metallosis, a type of localized metal poisoning characterized by muscle pain, inflammation, pseudotumors and osteolysis that can lead to implant failure. The metallic ions, generally chromium or cobalt, have also been associated with cancer and genetic damage.
After surgery, the surgically replaced joint will naturally be stiff as the muscles and tendons around the hip adjust. Patients will need to undergo physical therapy, including stretching and simple exercises, in order to recover the joint’s range of motion. Anti-inflammatory medication can also help with pain after the operation.
Two major nerves running into the leg, the sciatic and femoral nerves, are sometimes affected by hip replacement surgery. Joint manipulation during the procedure or swelling afterward can place pressure on the nerve, causing decreased sensitivity, weakness in the limb, pain, and decreased foot mobility. Often, there is no immediately obvious cause for the nerve problems, and symptoms can arrive without warning. Fortunately, though disconcerting, the condition is usually temporary.
Sources on manufacturers related to Hip Replacement:
Uneven Leg Length
Patients may come out of surgery with the sensation that one leg is longer than the other. This is most often due to altered muscle and tendon tension in the leg with the hip prosthesis; the feeling usually disappears as the body acclimates itself and the tendons adjust. In some cases (more commonly with revision surgery), the surgeon may need to alter the length of the leg to ensure stability of the implant, and to avoid complications related to muscle and tendon tension around the prosthesis. If the imbalance is enough to be noticed, patients can wear elevator shoes to compensate.
Sometimes, a hip implant can cause a squeaking, clicking or other noise. Ceramic-on-ceramic and metal-on-metal implants are particularly prone to this as the implant wears. While annoying, noise doesn’t necessarily mean anything is wrong with the implant. However, you should always consult with your doctor to be certain–squeaking can indicate serious problems, such as ceramic breakage.
Heterotopic ossification, the process by which soft tissue calcifies into bone, is one of the most common complications of hip replacement surgery and can lead to stiffness, pain, and a decreased range of motion. As many as 90 percent of hip replacement recipients experience some level of heterotopic ossification according to some studies; the occurrence of significant ossification is vastly lower, however. The calcified tissue generally appears 3-8 weeks after the procedure. It can usually be treated with nonsteroidal anti-inflammatory drugs or radiation therapy. In extreme cases, heterotopic ossification can cause implant failure and lead to revision surgery.
Dislocation can often be fixed with a noninvasive procedure called a closed reduction
The “ball” of the hip prosthesis may become dislocated from the socket. Dislocation can often be fixed with a noninvasive procedure called a closed reduction, wherein a doctor manipulates the ball back into the socket without an incision, sometimes under anesthesia. Multiple dislocations may lead to revision surgery, and a closed reduction can sometimes cause damage to the socket’s liner.
Over time, normal use may cause an implant to become loosened from the bone to which it’s affixed. This is more common with younger patients, those who lead more active lifestyles, or those who are overweight. This is often a consequence of other complications, such as osteolysis, a breakdown in the cement, or a failure of the bone to adhere properly to a cementless implant. The movement of a loosened implant can cause further bone loss, exacerbating the effects of osteolysis. Loosening usually requires revision surgery to correct.
Patients usually experience this, a fracture around a component of their implant, after a period of normal functionality, though it can occasionally be a complication of the surgery itself. A periprosthetic fracture is usually caused by a fall or other traumatic event, and most often affects the bone around the femoral stem. A loosened femoral stem is a serious risk factor for this injury, as are conditions such as muscle weakness and osteoporosis. This is a very serious, extremely painful complication that usually requires revision surgery to correct.
A pathologic fracture is a spontaneous fracture related to a weakness in the bone rather than to a significant trauma.
A pathologic fracture is a spontaneous fracture related to a weakness in the bone rather than to a significant trauma (e.g. a fall), though mild trauma can contribute. In hip implant recipients, this weakness is usually due to excessive bone loss. Pathologic fractures generally require revision surgery.
While hip replacement is often a solution to this particular problem, a loss of bone due to lack of blood flow, it’s also a potential side effect of hip resurfacing, usually in the femoral head. Avascular necrosis is bone death caused by a lack of blood flow to an area of bony tissue. The metal components used in hip resurfacing may seal the femoral head or other part of the hip joint off from blood flow.
Hip Implant Lifespan
Note that even when a procedure goes well, it may still be necessary in the future to replace the implant. Most implants are designed to function properly for 10-20 years; because recipients of hip implants tend to be older, this is generally long enough that only one implant is needed. Patients who received their implant at a younger age, or who lead active lifestyles, are more likely to need revision surgery at some point in their lifetime.
It is also rare, but possible, that the pain you experienced prior to the surgery may not be relieved by this operation and the pain may possibly become worse. You may experience a reaction to the cement used to keep the socket in place that could potentially be fatal.
Patients who have hip implants should be aware of potential symptoms that may occur after 3 or more months after surgery that may indicate that their device is not functioning properly. Possible symptoms include: pain in the groin, hip or leg, swelling at or near the hip joint, any change in walking ability, and any noise (popping, grinding, clicking or squeaking) from the hip joint. Inform your surgeon if any of these events occur. Depending on the severity, additional surgery may be necessary.
- McKee, J. (2008, February). Can surgeons win the fight against osteolysis and implant wear? AAOS Now, Retrieved January 6, 2014
- American Academy of Orthopedic Surgeons. (2007). Joint revision surgery: When do I need it? Retrieved December 31, 2013
- American Academy of Orthopedic Surgeons. (2013, May). Fracture after total hip replacement Retrieved December 31, 2013
- University Of Missouri School Of Medicine. (n.d.). Review of possible complications: Nerve injury. Retrieved from Total Hip and Knee Replacement website January 6, 2014
- University Of Missouri School Of Medicine. (n.d.). Review of possible complications: Leg length inequality and complications related to malalignment of the leg. Retrieved from Total Hip and Knee Replacement website January 6, 2014
- Leahy, M. (2010, June). Why some hips squeak. AAOS Now, Retrieved December 31, 2013
- Shimmin, A.J., et al. (2005). Complications Associated With Hip Resurfacing Arthroplasty. Orthopedic Clinics of North America (187-193). Retrieved from Surface Hippy January 6, 2014
- Orthopaedic Research Institute. (n.d.). The hip joint: How to recognize a failing hip replacement. Retrieved January 6, 2014
- Purdue, P. E., Koulouvaris, P., Nestor, B. J., & Sculco, T. P. (2006). The central role of wear debris in periprosthetic osteolysis. HSS Journal, 2(2), 102-113. doi:10.1007/s11420-006-9003-6
- Kocic M, Lazovic M, Mitkovic M, Djokic B. (2010). Clinical significance of the heterotopic ossification after total hip arthroplasty. Orthopedics, 33(1). Retrieved from Healio January 8, 2014