The right time to plan a hip replacement surgery is when the pain is so severe that it hinders your daily life tasks. This is an option to consider when medical treatment is ineffective, whether it is medication, physical therapy measures or the use of a cane or walker for walking.
Other possible signs may include: joint pain accompanied by periods of relative relief, pain after exercise, loss of mobility, loss of sleep, joint stiffness after periods of inactivity or rest and/or pain that increases with wet weather.
Generally, traumatologists delay the intervention of the hip prosthesis prioritizing the initial medical treatment, but if the joint damage is advanced, the intervention will offer the possibility of returning to the previous activities.
Types of hip prosthesis
It is necessary to differentiate between two types of hip prosthesis:
- Total hip prostheses; they replace both the femoral head and the cup. The part that is anchored in the femur is called stem, and a hemisphere or head is added to it, which will be the articular part. The stem is anchored to the bone by roughening its surface or by coating it with hydroxyapatite. If the bone is of poor quality, the anchorage is made by means of a special cement layer, which is placed between the stem and the bone. The prosthetic cup has a part that is anchored to the pelvis and a polyethylene piece that contacts the prosthetic head. The anchorage to the bone can be pressure, screwed, threaded or cemented.
- Partial hip prostheses; they replace only the femoral head, leaving the pelvis intact. The prosthetic head can form a single block with the stem, as in Thompson type prostheses, or be removable in isolation, forming part of a mobile dome (bipolar prostheses) that will allow it to be converted into a total prosthesis in the future. The pelvic cup alone is never replaced.
There are also rescue prostheses, which are used when the first prosthesis has worn out the bone and is loose (loosening or mobilization). They have a different design to adapt to the areas of bone loss, but the greater the number of pieces that compose it, the more friction there will be between them and the more debris will be detached, which will damage the bone even more.
Operation of hip prosthesis
Prior to hip replacement surgery, a preoperative study is performed, including a blood test, a chest X-ray and an electrocardiogram; however, additional tests may be required (pulmonary ventilation tests, echocardiogram or allergy tests).
General anesthesia or spinal anesthesia (from the back down) is used for the operation. In prosthesis replacements, general anesthesia is preferred, since they are usually longer and more laborious operations.
The skin incisions will depend on the surgeon’s preference for the approach; the patient will see a scar either on the lateral aspect of the hip, or forming a curve towards the buttocks (if it is a posterior approach).
Postoperative period after hip replacement surgery
After the operation, prophylaxis is performed with heparin for one month or with oral anticoagulants to prevent postoperative venous thrombosis (intravenous antibiotics will be administered during the operation).
On the second postoperative day the drainage tubes are removed, whose mission is to evacuate the residual bleeding that occurs after the operation.
At 24 hours a postoperative analysis or control hemogram is requested, which evaluates the possible anemia due to blood loss after the operation (generally around half a liter in partial operations, about one liter in total operations and between half a liter and two liters in replacement operations). If the losses are large, a blood transfusion may be required.
Pain is controlled with intravenous antibiotics for the first few days, and then taken by mouth for several weeks.
If the pain allows it, the patient sits the next day and the ambulation will be resumed as soon as possible, unless the surgeon determines a period without support (unloading) in some cases (for example, bone breaks around the implant during its insertion that need more rest without load for the consolidation of the process or in some types of dislocations).
In about five days with the serums removed, the patient is walking with two crutches or a walker; regardless of whether or not the limb is supported and if there are no complications, the patient can be discharged from the hospital.
The stitches are usually removed after 15-20 days at the orthopedic surgeon’s office.
Risks of the hip prosthesis operation
Among the risks or complications is infection; when it occurs in the first days or weeks it is usually due to some germ that penetrates through the wound from the air or the skin (it is impossible to sterilize them completely despite the aseptic conditions of the operating room).
When it appears later, it is due to a distant source of infection. The most frequent is from the urinary system or from caries.
The most usual treatment of the infected prosthesis consists of its extraction, a treatment for months with antibiotics (part of the time will be administered intravenously in the neck to avoid phlebitis in the arms) and, when the infection is considered eliminated, a rescue prosthesis is implanted. Until that moment the patient can walk with crutches, and in many cases can support the leg with relative strength, although he/she does not have a hip.
In some cases it may be recommended a cleaning operation only, leaving the prosthesis for the time being in case the antibiotic manages to eliminate the infection.
Another possible complication is postoperative hematoma, which is the accumulation of residual blood. It can become superinfected and sometimes it is necessary to perform a surgical cleaning intervention to drain it or the seroma, due to liquid exuded from the tissues (lymph, etc.).
If the prosthesis dislocates, the femoral part separates from the pelvic part. It occurs in about 5% of cases, and is more often associated with the posteroexternal approach (although this has other advantages), an inadequately positioned prosthetic cup, a short prosthetic neck and insufficient scar or muscle tension. In other cases it is due to a blow or torsion that dislodges it.
The first episode requires anesthetizing the patient and repositioning without the need to open the prosthesis (with some exceptions). If the prosthesis continues to dislocate, some or all of its components will have to be replaced.
When perforating the bone to implant the prosthesis, small fat emboli can form from the bone marrow (the marrow of the bone), which will go to the lung causing a fat embolism. In cemented prostheses the cement enters under pressure and can also cause cement embolism.
Each approach route can injure a nerve by proximity. The most common is injury to the sciatic or gluteus medius nerve. It is usually more frequent in prosthesis replacements due to the fact that the previous scar does not allow the structures to be seen well.
The same occurs with arteries. In replacements, an arterial branch neighboring the cup may be injured.
Fracture of the femur in the area of the stem due to trauma is favored when the bone has osteoporosis. It usually requires at least one osteosynthesis operation (fixation of the fracture fragments). Sometimes the prosthesis has to be replaced.
The calcifications around the prosthesis are sometimes very voluminous and impede the mobility of the hip, which indicates surgical removal when its growth has stopped (inactive phase calcification). They can be prevented by taking certain anti-inflammatory drugs for months, provided that digestive lesions do not appear due to their use.
Recovery of the operation of hip prosthesis
Normally, there is no need for subsequent rehabilitation in a specific center, because the patient gradually picks up the strength and mobility necessary for walking. The hip is a very grateful joint when it comes to rehabilitation.
Immediately after the operation for the implantation of a hip prosthesis, the patient will remain bedridden, so to promote their comfort and prevent complications after the operation, it is important to place a cushion or pillow between the legs to prevent them from making sudden movements as far as possible.
Once 24 hours have passed after the hip prosthesis operation, the patient will be able to stand up. To reduce to the maximum the impact and the direct support of the prosthesis the most advisable thing is that the patient uses a walker or crutches.
In most cases, while the patient remains in the hospital, the physiotherapist will help him/her with a series of postoperative exercises to recover strength in the muscles adjacent to the hip.
The first exercises will be of an isometric nature and will consist of the contraction of the abdominal muscles and the quadriceps of the affected leg. Exercises of displacement of the operated limb on the bed will also be performed to achieve mobility of the joint. Another common exercise is to perform flexion and extension movements to strengthen the legs and ankles.
Mobility after the operation of hip prosthesis
In most cases patients should resume normal activity within three to six weeks after surgery. Exercise during this period is critical as it is the best way to begin to regain mobility lost due to the disease that will be similar to pre-operative mobility.
The orthopedic surgeon will help you create an exercise program to begin functioning with the new hip prosthesis. This program will include: light walking around the house progressively increasing to longer walks outside the home, basic exercises such as rising from sitting to standing or climbing stairs.
In addition, you may be put with the help of the physical therapist to do specific exercises to restore mobility and strengthen the hip.