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Hip replacements and revisions

Anatomy

The hip joint is a ball and socket joint: head and socket fit together precisely. The hip socket is part of the pelvis. The hip head is the ball of the joint and is part of the femur. Both the socket ('acetabulum') and head are covered with cartilage that acts as the joint's sliding layer. In combination with the joint (lubricating) fluid, this ensures that the hip joint moves almost without friction. At the edge of the hip socket is a cartilage ring ("labrum"), which increases the bearing surface of the hip socket but mainly functions as a sealing ring to keep the synovial fluid in the joint. Around the hip joint is a very strong joint capsule. This ensures that the head remains in the socket. On the inside of the capsule is a thin layer of mucous membrane that produces the synovial fluid and lubricates the joint. Surrounding the hip joint are many muscles.

In addition to moving the leg, these actively contribute to the stability of the joint. The main hip muscle groups are: extensors, abductors and exorotators. Extensors are upper leg extensors. Especially the large gluteus muscle or gluteus maximus. You use the extensors particularly when rising from a seated position such as rising from a chair, car or toilet. The abductors swing the upper leg outward. Especially the middle gluteus muscle or gluteus medius. The abductors stabilize the pelvis when walking. A weakness of these muscles results in a typical and annoying waddling gait pattern (Trendelenburg gait). The exorotators (which turn the upper leg outward) a.o. piriformis muscle. The exorotators also stabilize the hip.

Wear

The function of the hip is to carry and propel the body. Although great forces are placed on the joint and cartilage in this process, the most common cause of hip wear (coxarthrosis) is a shape defect or abnormal fit of the head in the socket, such as hip dysplasia or hip impingement. When the hip wears down, the cartilage becomes thinner and thinner and the typical abnormalities occur, which can often be seen clearly on an X-ray. Patients with a worn-out hip are characterized by increasing pain and loss of range of motion.

Symptoms

Typical symptoms associated with a worn hip are:

  • Pain in the groin and/or buttock region with radiation to the knee
  • Pain when starting movement
  • Stiff feeling especially in the morning
  • Pain in the groin or buttock when going through the legs, getting up from a chair or climbing stairs
  • Nocturnal pain around the hip
  • Less strength in the upper legs or fatigue after exercise

Btreatment

Initially, these symptoms can be treated, often successfully, without surgery. Your family doctor can also advise you on this. Medication in the form of anti-inflammatories (NSAIDs such as Diclofenac) or special exercises prescribed by a physical therapist can help. An injection of corticosteroids into the hip joint can also temporarily suppress the inflammatory reaction that arises in the joint with osteoarthritis. Over time, however, there is a chance that all these conservative remedies will no longer have the desired effect and the patient will be considered for the placement of a hip prosthesis.

Total Hip Prosthesis (THP)

A total hip replacement consists of 3 parts: the head, the socket and the stem.

  • The head is spherical and made of ceramic. The head is attached to the hip stem and rotates in the hip socket. The size and length can be adjusted to fit your own anatomy.
  • The hip socket is placed in the pelvis. It consists of a titanium bowl into which a bearing is placed. This can be made of ceramic or polyethylene. All materials are body friendly.
  • The hip stem is made of titanium and coated with a hydroxyapatite, a special coral-like material that allows ingrowth into the bone.

The final choice made by the surgeon depends on a number of factors such as the quality of your bone and the presence of any congenital defects of the hip joint.

Surgical approaches

Before a hip replacement can be placed in the bone, the orthopedic surgeon must first make an access (approach) through the skin and subcutaneous tissues. There are several ways to do this. The most common approaches are behind the hip bone (posterior approach) or in front of the bone (lateral approach). Both methods require loosening muscles to reach the hip joint. The lateral approach is reliable, gives good results and little chance of luxation (dislocation).

A major disadvantage, however, is that this involves loosening important muscles on the front to back side that are essential for walking. This can lead to a wobbly gait (Trendelenburg gait). Pain at the side of the hip can also occur, which is often difficult to treat. The posterior approach requires loosening of muscles that have an important function in the stability of the hip. Post-operative treatment is restricted in the beginning to prevent luxation and the risk of this happening after the operation is 3-4 %.

Benefits DAA

With the anterior approach, no muscles need to be loosened to reach the hip joint. In particular, the important muscles for a stable gait (without swelling) remain completely unaffected. Damage to important nerves around the hip joint is also much less with this technique. The risk of the hip dislocating is smaller than with other approaches to hip replacement. The wound made with this method is not smaller than with the other surgical techniques although we try to make it as small as possible. The scar is between 10 and 15 cm long. So the benefit of the anterior approach is not so much a smaller scar, but keeping the muscles that are important for walking and for the stability of the hip intact. This leads to less pain, a more stable hip and an easier recovery during the first months after surgery.

Disadvantages DAA

A disadvantage of this approach is the risk of damaging a nerve that provides sensation on the front to back side of the thigh. This occurs in approximately 3-5% of cases. Fortunately, this is often transient and the patients, who are left with an (often small) area of altered or decreased sensation around the scar, do not describe this as bothersome.

Post-treatment DAA

Because the muscles around the hip remain intact, you experience a high degree of stability. This also allows the after-treatment to be less severe. For example, you may:

  • On the day of surgery, get out of bed and walk (with one or without crutches)
  • If you can and want to, go home the same day. (Usually patients go home the day after surgery)
  • Use crutches for as long as you want
  • sleeping on the side
  • exercise bike
  • driving (as soon as walking with one crutch is possible)

Nevertheless, take into account a recovery period of two to three months. That is how long the body needs to regain its flexibility and strength.

Complications

The most common complication of total hip replacement is a post-operative wound infection, this occurs in about 1% of cases and also depends on smoking, diabetes and obesity. Should a wound infection occur, the wound will become red and continue to leak for more than 10-14 days. A re-operation in which the wound is flushed in combination with antibiotics produces a good end result in almost all cases.

More information on:

Knee prosthesis
Knee
Shoulder prosthesis
Shoulder
hand wrist correction
Hand/wrist/elbow
Injections with hyaluronic acid
Injections with hyaluronic acid