Hip arthroplasty

Hip arthroplasty (hip arthroplasty) is a surgical procedure consisting in replacing a damaged hip joint with an artificial implant. The purpose of endoprosthesis implantation is to relieve pain and improve the range of motion, which has a positive effect on the quality of life of people with the last degree of degenerative hip changes. The continuous development of surgical techniques and the improvement of biomaterials used in prostheses mean that hip arthroplasty is not only reserved for the elderly, but is also one of the effective methods of treatment also in younger patients who have irreversible damage to the hip joint.

Indications for hip joint endoprosthesis

Degeneration of the hip joint - coxarthrosis

Degenerative changes in the hip joint involve the gradual destruction of articular cartilage followed by degradation of the underlying subchondral bone layer. The head of the femur loses its round shape over time and cannot move freely relative to the hip socket. In addition, bone outgrowths (osteophytes) form at the edges of the joint that conflict with the surrounding tissues. As a result of local damage, secondary inflammation occurs in the synovium of the joint capsule, ligaments and even the tendon sheaths of adjacent muscles. The capsular-ligamentous apparatus becomes thicker and loses its elasticity, preserving the restriction of movement in the hip joint.

The main symptom of osteoarthritis of the hip is pain in the groin when the leg is loaded with body weight. In advanced stages of degeneration, hip pain also occurs when moving the limb with relief or even at rest. The range of motion is gradually reduced until the hip stiffens. A significant predominance of the degeneration of one of the hip joints can lead to shortened limb length, limp gait, and secondary back problems.

Other indications for hip arthroplasty:
fractures within the femoral head,
femoral head necrosis,
hip fractures,
complicated fractures of the acetabulum with displacement,
tumors involving the hip joint.
The endoprosthesis procedure is designed to reduce pain, increase hip mobility, improve biomechanical conditions of the iliopsoil-lumbar complex and enable a smoother gait. The artificial hip successfully replaces the main functions of the natural joint - the patient is able to move the limb and walk without limping, thanks to which the quality of life is significantly improved.

Types of hip joint endoprostheses

Depending on whether both articular surfaces or one are replaced, we can distinguish endoprostheses:

Hemi- endoprostheses - consist of a shaft embedded in the femur and head. Half prostheses are used in elderly people with low activity, whose aim is to reduce pain and enable moving around the apartment and walking for short distances.
Total - consists of a shaft, head and an artificial acetabulum.

Due to the structure of the head, the hip prosthesis is divided into:

Unipolar - a single head connected to the pin has direct contact with the acetabulum,
Bipolar - the head connected to the pin is additionally connected to the second larger one placed in the hip joint socket. There is movement between the heads so that the frictional forces acting on the hip socket are reduced.

Types of articulation

The head of the prosthesis can be made of metal, polyethylene or ceramics. The metal cup of the prosthesis has an internal polyethylene or ceramic insert that cooperates with the head of the prosthesis. The connection of the prosthesis elements (articulation) can take the following versions: ceramics-polyethylene or ceramics-ceramics. The bearing type determines the survival rate of the endoprosthesis and also affects the price of the hip implant.

Cementless, cement and hybrid endoprostheses
Cementless endoprostheses have a porous surface which fuses with the patient's bone. The stem is placed in the medullary canal of the femur by the impaction method, and the acetabulum is placed on the press-fit or screwed into the bone. The surfaces of some models of endoprostheses may be coated with hydroxyapatite or titanium, which facilitate integration with the bone bed.

When the acetabulum is secured with bone cement and the stem is wedged without bone glue (or vice versa), this is called hybrid endoprosthesis.

Hip prostheses with a modular neck
In some of the newer models of prostheses, it is possible to adjust the femoral neck anthroat angle and the cervical-molar angle intraoperatively. As a result, the neck is optimally positioned in relation to the acetabulum, which reduces the risk of endoprosthesis dislocation.

Hip joint capoplasty

Capoplasty is a procedure that conserves the head and neck of the femur. The surgeon removes only the damaged articular cartilage and the subcartilage layer of the bone. An oval overlay is placed over the rest of the head in contact with the hip socket. The advantage of capoplasty is the possibility of later replacement with a classic endoprosthesis, less interference with the natural biomechanics of the hip and the possibility of early loading. Therefore, capoplasty of the hip joint can be successfully used in middle-aged patients with good quality bone tissue and who have not yet developed large deformities of the femoral head.

Short-term endoprostheses

Another option for younger patients is a short stem hip replacement that penetrates less into the femoral canal - mainly the spongy bone of the epiphysis. The advantages of this type of endoprosthesis include more favorable biomechanics, including obtaining a more physiological stress distribution within the proximal femur, which promotes osseointegration of the prosthesis with bone tissue and reduces the risk of loosening. Short-term endoprostheses allow, among others, to reduce the risk of the phenomenon of "stress-shielding" in the proximal part of the femoral shaft, which is the reduction of bone density due to inadequate stimulation with load.

Revision endoprostheses

Sometimes a hip prosthesis has to be replaced with a new one - this procedure is called realloplasty. It is necessary to replace it with a revision prosthesis in the case of:

Periprosthetic inflammation as a result of infection - this is the so-called septic loosening of a hip implant, An example is endoprostheses with an antibiotic of the Spacer type used to heal the infection.
Aseptic loosening of the implant (without infection),
Mechanical damage to the hip prosthesis.

Revision endoprostheses may have additional stabilizing and strengthening elements, e.g. a cup with an anti-protrusion system, preventing further damage to the pelvic bone base by the prosthesis head.

Eligibility for surgery

When qualifying for endoprosthesis implantation, the orthopedist takes into account not only the structural changes in the hip joint, but most of all the functional aspect of the procedure, the patient's age, level of activity and readiness to undertake rehabilitation after surgery. It is very important for the patient to understand the essence of arthroplasty - it is a highly intrusive procedure with an increased perioperative risk due to significant blood loss, and also with a risk of postoperative complications in the event of non-compliance with the recommendations of the doctor and physiotherapist.

Endoprosthesis implantation is considered when the methods of conservative treatment are ineffective, other methods of surgical treatment do not repair the damage (e.g. arthroscopy of the hip joint or anastomosis with DHS screw), and the degree of deformation, pain and restriction of mobility significantly reduce the patient's quality of life.

The doctor analyzes the X-ray image of the hip joints, on which he assesses the extent of the destruction of the articular surfaces and bone deformities. In the case of post-traumatic conditions, it may be necessary to perform a CT scan or MRI of the hip.

In each case, contraindications to hip arthroplasty should be considered, which include:

chronic failure of the cardiovascular and / or respiratory systems,
thromboembolism,
severe osteoporosis,
severe obesity,
a history of stroke or other neurological diseases that significantly affect the tone of the hip muscles,
dementia and other mental illnesses that make it impossible to follow the instructions after the procedure.
Preparation for hip replacement surgery
Properly conducted physiotherapy before surgery allows for a much faster recovery after hip replacement surgery. The management includes techniques to reduce the contracture of soft tissues, which helps surgeons to correctly implant the endoprosthesis. The aim of the exercises should be to increase the muscle strength of the hip girdle, with particular emphasis on strengthening the middle gluteus muscle, which acts as a dynamic hip stabilizer during walking. This muscle is usually cut during surgery, so the greater the initial strength you gain before the procedure, the easier it will be to rebuild it during postoperative rehabilitation. An important element of physiotherapy is also educating the patient on how to adapt the apartment to the needs of a person with hip arthroplasty.

Before the operation, you should visit the dentist and heal the sick teeth. Other conditions, such as sinusitis or urinary tract inflammation, also need to be completely healed before surgery. This is very important due to the fact that active infection foci can cause blood-borne infection of the hip prosthesis and its secondary septic loosening.

The course of arthroplasty of the hip joint

The surgical procedure is performed under epidural or, less frequently, general anesthesia. Surgical access can be broadly divided into anterior, anterior-lateral, and posterolateral access. The advantage of surgical accesses located more in front of the hip joint is less traumatization of the muscles of the hip girdle, which positively affects the upright position and quality of gait after the procedure.

The surgeon cuts off a specific part of the proximal femur - the size of the excision depends on the type of endoprosthesis, it may be a part of the head (capoplasty) or removal of the head and neck of the femur (classic stem endoprostheses). Within the acetabulum, the debris of damaged cartilage is removed and the bone matrix is ​​prepared for the installation of an artificial acetabulum (total endoprostheses).

Complications of arthroplasty

Prevention of early complications (thrombophlebitis or pneumonia) consists in administering drugs (heparin), performing anticoagulant and respiratory exercises, and early upright positioning of the patient after the procedure. The complications directly related to the operated hip include: infections and loosening of the implant (related to infection or wear of the implant), as well as endoprosthesis fractures and dislocations (most often post-traumatic due to a fall).

Infections of the operated joint (infection)

The cause of infection in the operated area is usually untreated infections in the patient's body (sinusitis, urinary tract inflammation) or active tooth decay. In addition to proper preparation before the surgery, as part of additional prophylaxis, the patient undergoes antibiotic therapy, which begins the day before the surgery and lasts up to several days after the surgery. Moreover, the operating room should meet the requirement of special sterility.

If you notice any symptoms of infection (fever above 38.5 °, pain and heat in the hip area, and swelling in the wound area and / or exudate), consult your doctor immediately.

When the tissues around the artificial hip become infected, the endoprosthesis is removed, the hip area is thoroughly rinsed and a transient endoprosthesis with an antibiotic is placed for a specified period of time. Only after the infection has fully healed, a new hip replacement is placed.

Aseptic loosening of the implant

Aseptic loosening of the implant (without infection) can occur after prolonged use, when the hip prosthesis is embedded in the soft bone of a person suffering from osteoporosis. The problem of loosening is more common in the case of cement prostheses, usually several years after the operation, when the properties of the cement deteriorate. The risk of loosening of the hip replacement is greater when the implant is overloaded (obesity, playing sports) and if comorbidities are not treated (diabetes, liver diseases).

A big problem is the loss of bone tissue around the prosthesis, because the contact surface of the implant with the bone is reduced, which creates a risk of instability of the newly put on prosthesis and re-loosening. To prevent such a situation, the surgeon, during realloplasty, can reconstruct bone defects using bone grafts.

Rehabilitation after hip joint endoprosthesis

Immediately after the surgery, the operated limb should be placed in a safe position that protects it from excessive addiction and rotations. At the same time, the patient performs active flexion and extension exercises in the ankle joint to stimulate the muscle pump and prevent thrombophlebitis. The first movements of the artificial hip joint are carried out passively and to a limited extent on a special splint. Then the patient under the control of a physiotherapist performs isometric tension of the muscles and gradually turns on the active movements of the knee and hip. On the second day after the procedure, the patient should be able to safely sit down, get up and walk with the help of a walking frame. The patient's stay in the hospital usually lasts several days - during this time the patient adapts to the upright position, starts to use elbow crutches instead of a walking frame, learns to climb and descend stairs by himself. The degree of limb loading depends on the type of endoprosthesis (cemented / cementless / spacer) and the presence of possible complications.

The main goal of rehabilitation after hip endoprosthesis is to restore the maximum possible efficiency taking into account all the circumstances depending on the course of the procedure and the type of endoprosthesis. The exercises are designed to strengthen the muscles of the hip girdle, especially those that were cut during the procedure. When it is possible to fully load the operated limb, an important task of rehabilitation is learning to walk with the correct positioning of the pelvis and symmetrical work of both legs. It is very important to include exercises to improve body stability and balance exercises, thanks to which we reduce the risk of falls and possible mechanical damage to the prosthesis as well as sprains and periprosthetic fractures. After completion of individual therapy with a physiotherapist, the set of exercises after hip replacement should be continued by the patient at home.
Living with a hip replacement
After hip replacement surgery, remember to exclude movements and positions that are not advisable due to the increased risk of implant dislocation. Avoid excessively twisting a limb in or out, folding one leg over one leg, doing squats, sitting on too low armchairs or on a bed (when the knees are higher than the hips) and taking a crouched position with the legs against the chest. In any position, the position of the thigh in relation to the torso should not exceed 90 °.

It is worth adjusting the apartment to facilitate the safe performance of everyday activities:

seat and anti-slip mat in the bathtub, additional handles in the bathroom,
toilet seat cover,
pillows for too low armchairs or chairs,
non-collapsible mattress on the bed.
The recommended activities after hip arthroplasty are walking, cycling and swimming on the back or crawl (the classic style, the so-called "frog" style, is contraindicated due to the large range of hip rotation). It is better to refrain from practicing contact sports and sports with a high risk of falling (skis, roller skates), as the treatment of periprosthetic fractures can be difficult and long-lasting.

Important information

Frequently asked questions about the hip replacement procedure: