Conservative hip surgery
What is hip dysplasia ?
The hip is the joint between the pelvis and the femur. The top of the femur is composed of a head and a neck which pivots in a socket in the pelvis called the acetabulum. The sliding surfaces are lined with cartilage and numerous muscles and tendons surrounding the capsule ensure the mobility of the hip and a balanced gait (figures 1).
Dysplasia is an abnormal shape of the hip that can lead to its premature wear.
Most often, the acetabulum is too shallow (figure 2), the angle of the femoral neck is too excessive (figure 3), or it is a combination of the two (figure 4).
The weight-bearing zone is thus reduced, increasing the pressure on the cartilage and leading to its progressive deterioration.
These modifications cause pain in the hip as well as limping and require the use of anti-inflammatories, painkillers and sometimes a walking stick.
Why an operation ?
The shape of the hip does not correct itself spontaneously and so the natural progression is the complete wear of the cartilage, with increased discomfort and difficulty in walking. We thus talk of advanced hip osteoarthritis requiring replacement.
The anti-inflammatories and painkillers that were enough to start with are no longer effective, and so the question of surgery is raised.
The objective of the operation is to relieve the part of the hip under excessive pressure, and slow wear in young subjects. This will relieve the pain and slow the progression of the osteoarthritis.
What is conservative hip surgery ?
Conservative hip surgery aims to distribute the pressure on the acetabular cartilage and the femoral head better. According to the deformity, the surgery consists in increasing the depth of the acetabulum, decreasing the angle of the femoral neck, or combining the two procedures.
In the case of an excessive angle of the femoral neck, a femoral varising osteotomy is indicated:
An incision is made on the side of the hip. The top part of the femur is exposed and the femur bone is cut just below the neck using a saw (figure 5). The correction of the angle of the femoral neck is achieved by opening up the cut (figure 6). The size of the opening is calculated according to the initial deformation and controlled by a perioperative x-ray. A plate is then fixed with screws to maintain the correction (figure 7).
In the case of a shallow acetabulum, acetabular augmentation is indicated :
An incision is made in the top part of the hip and the external part of the acetabulum is exposed. A bone graft is taken from the pelvis and fixed with one or two screws to the external part of the acetabulum, just above the femoral head (figures 8 and 9).
In the case of an excessive angle of the femoral neck and an insufficient covering of the acetabulum,
the two procedures are performed at the same time through a longer incision (figure 10).
After the operation, the incisions are covered with a sterile dressing, which is left in place for 10 days. The pain will be managed and monitored very closely during the post-operative period, and the treatment will be adjusted accordingly.
Post-operative rehabilitation and return to activities
The day after the operation, the physiotherapist will get you up and help you to walk. In the case of an augmentation, you will have crutches to help you move around for 6 weeks so as not to put too much weight on the hip, and for two and a half months in the case of a femoral osteotomy.
The rehabilitation is carried out with your physiotherapist or in a rehabilitation centre. The objective is firstly to reduce the initial pain and maintain flexibility and mobility, then to recover muscle strength and sensations in the hip.
Driving can be envisaged after the 2nd month following an augmentation and after the 3rd month following a femoral osteotomy. You can generally return to work after the 3rd month, depending on your profession; office work can be sooner. A progressive return to gentle sports activities can generally be envisaged after the 6th month
What are the risks and complications ?
In addition to the risks associated with any surgery and the anaesthetic, there are some risks specific to this surgery :
- Joint stiffness can develop if the post-operative rehabilitation is not carried out properly.
- A haematoma may appear around the area operated on due to bleeding. According to the degree of bleeding, drainage may be necessary.
- The occurrence of an infection, although rare (risk below 1 % in our establishment), is a serious complication and may require surgical revision and a course of antibiotics.
- Small blood clots can form and block the veins in the legs resulting in phlebitis, which will require an anti-coagulant treatment for several weeks.
- The nerves around the hip may be injured accidently. This rare complication may cause pain and a loss of feeling in certain parts of the thigh.
- The cut bone may not heal. An unwanted fracture of the joint can occur as well as an insufficient or excessive realignment. These complications, although rare, may require surgical revision.
This list of risks is not exhaustive. Your surgeon can provide you with any additional explanations and will be available to discuss the advantages, disadvantages and risks of each specific case with you.
What is the expected outcome of the operation ?
The results of this technique are well known as the procedure is over 40 years old. An improvement in pain is observed in over 90 % of cases. Normal walking without limping is generally recovered in the 3rd month post-op in the case of an augmentation and in the 6th month post-op in the case of a femoral osteotomy. The resumption of activities is often unrestricted.
Contrary to replacements, the hip remains totally natural and all types of sports activities are possible. Nevertheless, certain demanding activities involving extreme movements of the hip or running can promote the deterioration of the cartilage and comprise the long-term result.
The beneficial effect of conservative hip surgery is on average about fifteen years, thus delaying hip replacement by as many years.