Advances in

Hip and Knee Replacement

John R. Moreland, M.D.

Over the last 5 to 10 years there have been major advancements in hip and knee replacement surgery. Three areas are particularly important and deserve further discussion. Many patients delay hip and knee replacement because of concern about a long recovery, severe postoperative pain, and problems with the durability of the replacement.Fortunately,there have been dramatic advances on all three issues.

Recovery Duration and Minimally Invasive Hip Replacement

The recent advance that has gotten the most publicity is minimally invasive hip replacement, whichutilizes shorter incisions with less muscle and other soft tissue trauma, allowing and facilitating immediate weight bearing as tolerated with a quicker return to normal daily activities than in the past.While not the first surgeon to adopt the new minimally invasive hip replacement techniques, Dr. Moreland now routinely uses a minimally invasivesurgical approach facilitated by a minimally invasivehip prosthesis.

There are several variations among thenew minimally invasive hip replacement techniques.One major difference is whether the hip is approached anteriorly or posteriorly. Dr. Moreland prefers an anterior approach, since it has a lower dislocation rate than the posterior approach and can be done without cutting any muscles or tendons. The posterior approach always requires cutting some of the posterior muscles which can not be repairedadequately.

Some surgeons using the anterior approach strap the patient’s feet in the boots of a fracture table for operative manipulation and use an image intensifier x-ray machine to help visualize the hip during surgery. Everyone in the operating room,except the patient, wears lead shielding to prevent radiation exposure. The patient can not be shielded and receives radiation in the important area of the gonads. Dr. Moreland’s minimally invasive anterior surgical approach is done with the patient on the side on a regular operating table without the image intensifier and without exposing patients to the radiation it produces.

Minimally Invasive Knee Replacement

With the success of minimally invasive hip replacement surgeons have also tried to duplicate that success with minimally invasive techniques for knee replacement which simply emphasize shorter incisions. It is not clear that this is a significant advance since there have been many reports of increased complication rates with very small knee incisions and the resultant decreased exposure available for the surgeon to do the operation. It has not been shown that patients recover significantly faster with shorter incisions, since the tissues receive additional trauma from the severe retraction necessary to get adequate exposure with very short incisions. Minimally invasive knee replacement today is actually more marketing than an advance. Knee replacement patients have always been allowed to bear weight as tolerated from the first day. Dr. Moreland uses as short an incision as possible consistent with the need for adequate exposure to do the operation correctly. No muscles or tendons are cut. Recovery is relatively quick with patients by one to two weeks after surgery routinely walking with a cane and reporting that they are already better than before surgery.

Durability of Hip Replacements

Wear of a hip replacement was the last major unsolved problem affecting the long term durability of hip replacements. New bearing materials have been developed and are now in common use and the wear of the current generation of hip replacements is dramatically less than was seen with older types of hip replacements. Loosening of the implants was the other main threat to hip replacement durability and was basically solved with the advent of cementless hip replacement of various designs over 20 years ago. Hip replacements today should last a lifetime for most patients and even for those whovigorously and regularly exercise.

Durability of Knee Replacements

Better knee replacement designs along with new materials havealso dramatically increased the durability of knee replacements such that most patients can expect that their knee replacements will last a lifetime. The best fixation technique for the knee, in contrast to the hip, remains cementation.

Postoperative Pain Control for Hip and Knee Replacements

Revolutionary postoperative pain control techniques were introduced about at the same time as minimally invasive replacements and many authorities believe the pain control techniques are more significant. In the past postoperative pain was simply treated with narcotics until the patient was more comfortable. There are many problems with this approach. Patients need widely varying amounts of narcotics for pain control. Since too large a dose of narcotics can cause the patient to stop breathing, physicians must first use lower doses for safety and then gradually increase the dose, if initial doses are not sufficient. Patents thus can be in a lot of pain before an adequate dose of narcotics is determined and delivered. Narcotics have many side effects, including sedation, confusion, hallucinations, respiratory depression, nausea, vomiting and constipation.

If a patient feels a lot of pain, the brain becomes sensitized to pain and perceives subsequent pain more intensely. It is important that this brain sensitivity not be allowed to develop.Today we emphasize treating postoperative pain before it occurs and also utilize severalnonnarcotic pain medications.Narcotic medications are still used but in smaller doses.

The morning of surgery patients are given Celebrex which is very effective for postoperative pain. Acetaminophen (Tylenol) is also given along with a dose of Oxycontin which is long acting, well tolerated, and effective narcotic.A spinal anesthetic is recommended rather than a general anesthetic. With a general anesthetic the brain still knows that an operation is occurring and is being sensitized to postoperative pain. With a spinal the brain receives no pain impulses. Patients are sedated and are completely unaware during the operation. Spinal anesthetics also have the advantage of less bleeding and fewer postoperative problems with blood clots.A small dose of narcotics is injected with the local anesthetic of the spinal anesthetic. This can give pain relief for 12 hours or more. The gastrointestinal tract is not exposed to this narcotic dose and GI side effects are minimized.

At the end of the operation before wound closure the wound is injected with a long acting local anesthetic similar to the Novocain used by the dentist. The pain relieving effects of this may last 12 hours or more.Postoperatively patients receive Celebrex and the long acting narcotic Oxycontin.

Most hip and knee replacement patients with these pain control techniques have dramatically less pain than in the past with fewer medication side effects.

More Information

If you would like more information about hip and knee replacement, please call Dr. Moreland’s office at 310-453-1911 and we can send you copies of his booklets on hip and knee replacement surgery.