Unlike total hip replacement the number of procedures is steady with 38,000 performed in 2006.
Most common reasons for patients needing this revision surgery includes dislocation of the hip prosthesis, loosening of the implant and infections.
Hip bearing surface wear and and osteolysis account for 15% of such procedures.
Joint revision surgery is a complex, and requires extensive preoperative planning, specialized implants and tools.
Results of revision total hip arthroplasty have improved with improved cementing techniques.
Loosening of the joint is a result of friction of the joint surfaces rubbing against each other wearing away the surfaces of the implant, creating tiny particles.
These particles accumulate around the joint, and the bonds of the implant to the bone are destroyed by the body’s attempts to digest the wear particles.
As the prosthesis loosens, the patient may experience pain, deformity, or instability.
The above process is called aseptic, or noninfected, loosening.
Lysis also digests normal bone with weakening or even fracturing the bone, and jeopardize the success of the revision surgery.
Aseptic loosening is the most common mode of failure of hip implants.
Because the large foreign metal and plastic implants can serve as a surface for bacteria to latch onto, infection can cause of implant failure.
Tissues that has been previously operated on have an altered blood supply, which may impair the body’s ability to fight infection.
Infection, even if the implants remain well-fixed, ,ay lead to the, swelling, and drainage making revision necessary.
Risk of infection with current surgical techniques and antibiotic regimens is about 0.5%.
The rate of dislocation after hip replacement ranges from zero to 10%, but averages about 2%.
Some indiviuals may experience multiple dislocations and require revision.
Dislocation may be caused by loosening, inadequate soft tissues, bony or scar tissue impingement, incompatible component position, neurologic factors, or patient noncompliance.
Revisions are more common in younger and more active patients and in the obese.
Primary hip replacements for inflammatory arthritis, avascular necrosis, and patients with a previous hip fracture are at higher risk for loosening.
The natural history of failed implant is an increase in pain, a change in the position of the implant, or a decrease in the function of the implant with limp or dislocation.
The evaluation for assessment of such a symptomatic patient includes a history and physical examination, X-rays, laboratory tests, and possibly aspiration or scintigraphic studies.
Pain of the hip may present as either groin or buttock pain or sometimes as knee pain.
Increased redness and swelling may be present at the hip joint in an infected patient.
A limp or deformity may be identified in infected patients.
X-rays of the joint replacement may yield important clues regarding stability of the implant including aseptic loosening noting that the implant may have moved, compared to previous X-rays, or there may be a lucent line between the component and the cement or bone, signifying that the bond between the bone and implant has degraded.
Plain x-rays may identify areas of bone lysis, mechanical failure with broken implants or severe wear.
Serial x-ray examinations are recommended to diagnose joint failure.
Laboratory tests for possible failed joints include a complete blood count, an erythrocyte sedimentation rate (ESR), and a C-reactive protein test (CRP).
Aspiration of the hip joint may identify patients with infections.
Bone scan studies may indicate the presence of increased activity due to infection, fracture or prosthetic irritation from motion.
Indium scans may help in identifying the presence of infection.
Rates of complications occurring within 90 days of surgery are mortality of 2.6%, 0.8% for pulmonary embolism, 0.95% for wound infection, 10% for hospital readmission and 8.4% for hip dislocation.