A hip arthroplasty, commonly called a total hip replacement, is performed when the hip joint is functioning poorly and causing the patient considerable pain or decreased range of motion. Osteoarthritis, rheumatoid arthritis, or arthritis following a trauma are likely causes for undergoing the procedure. The surgery is very common, and although there are generally good outcomes, complications are possible.
Deep Venous Thrombosis
A deep venous thrombosis, or DVT, is a common complication following any surgery or prolonged period of bedrest. A DVT is a blood clot that forms usually in the leg. DVTs can lead to a pulmonary embolism when pieces of the blood clot break off and travel to the lungs. Pulmonary embolism can be fatal.
Surgeons will give patients medications and mechanical interventions to reduce the risk of DVTs. Medications that decrease blood clotting or "thin the blood" include coumadin, heparin, or Lovenox. Mechanical interventions that decrease the risk of blood clotting include anti-thromboembolism stockings and pneumatic boots.
Neurovascular Injury
During a hip arthroplasty, nerves or vessels can be injured by either the placement of the hip replacement or by a traction injury. According to the "AAOS Comprehensive Review" edited by Dr. Jay Lieberman of the University of Connecticut Department of Orthopaedics, traction injuries occur when the nerves or vessels are injured from being stretched. Nerve injuries usually occur to the sciatic nerve leading to sensory deficits and weakness in the leg.
Vascular injuries can also occur with the placement of screws to secure the prosthetic cup component into the acetabulum. Vascular injury can lead to large amounts of blood loss or blood pooling in the tissues--a hematoma. Total hip arthroplasty in itself can lead to significant blood loss often requiring a blood transfusion. Some patients will store their own blood in the blood bank to be given back to them during the surgery or during the post-operative period.
Fracture
Placement of the cup or the stem component of the total hip arthroplasty can lead to fracture. According to the "Handbook of Fractures" edited by Dr. Kenneth Koval of Dartmouth Hitchcock Medical Center and Dr. Joseph Zuckerman of New York University-Hospital for Joint Diseases, the stem component being placed into the femoral shaft can result in fracture. Intraoperative fractures are uncommon in primary total hip arthroplasty, however are more common in revision surgeries. Surgeons will usually identify these fractures in the operating room and fix them during the procedure with wires or a different prosthesis. Post-operatively, patients can have periprosthetic fractures that occur through the bone surrounding the hip replacement. These periprosthetic fractures are typically due to trauma.
Dislocation
Dislocation of the stem from the cup usually can occur after surgery. Depending upon the incision site, patients are given a series of precautions on what positions to avoid to reduce the risk of dislocation. According to the American Academy of Orthopaedic surgeons, physicians may advocate that a patient does not cross his/her legs, bend the hip to more than 90 degrees, and turn the feet too far inward or outward. Placing a pillow between the legs can also help reduce the risk of dislocation until the physician states it is no longer necessary to do so. Physical therapy can be helpful to strengthen the soft tissues structures around the hip replacement. Chronic and recurrent dislocations may require placement of a different type of hip replacement.
Infection
Infection is a common cause of post-operative complication with any surgery. To reduce the risk of post-operative infection, sterile operative procedure is critical to prevention. According to the "AAOS Comprehensive Review" edited by Dr. Jay Lieberman of the University of Connecticut, infections that occur six weeks to three months post-operatively usually result from the surgery. Infections after three months can occur from blood borne bacteria. Many surgeons advocate the use of antibiotics before dental procedures to reduce the risk of blood borne bacteria infecting the hip replacement. Infected prosthetic devices may require removal of the hip replacement and other procedures leading up to undergoing a new hip replacement.
Heterotropic Ossification
Heterotopic ossification is calcification of tissues around the hip replacement. Calcification of tissues refers to the process of bone formation outside the skeleton. The "AAOS Comprehensive Orthopaedic Review" edited by Dr. Jay Lieberman of the University of Connecticut states that the prevalence of heterotopic ossification is as high as 80 percent after a total hip arthroplasty. Surgeons may advocate taking oral indomethacin or undergoing radiation therapy within 72 hours of the surgery to help reduce the risk of heterotopic ossification. These are treatments to help decrease the formation of bone outside the skeleton.
Limb Length Discrepancy
Limb lengths are checked in the operative room and there is an attempt to make the legs the same length. Sometimes tension in the muscles and other soft tissue structures makes it impossible to make even leg lengths or there is concern for causing stretch injuries to the neurovascular structures. The American Academy of Orthopaedic Surgeons recommends that surgeons warn patients about the side effect of limb length discrepancy as a possible unavoidable outcome.
Loosening
Although newer hip replacements are less likely to have component loosening, it is still a cause for concern. Loosening can be very painful in the groin or thigh. There can be a new limp as the component loosens. The "AAOS Comprehensive Orthopaedic Review" edited by Dr. Jay Lieberman of the University of Connecticut states that loosening typically requires placement of a new prosthesis. Over time, the components can also wear and lead to complications and need for revision surgery.
References
- "AAOS Comprehensive Orthopaedic Review"; Dr. Jay Lieberman; 2008.
- American Academy of Orthopaedic Surgeons: Total Hip Replacement
- Wheeless' Textbook of Orthopaedics: Total Hip Arthroplasty
- "Handbook of Fractures"; Dr Kenneth Koval, Dr Joseph Zuckerman (editors); 2006.
