Total hip replacement

Total hip replacement is a surgical procedure in which the damaged surfaces that form the hip joint (HJ) are replaced with prostheses. This operation was first carried out in the 60s of the last century and is currently considered one of the most successful operations of recent decades. A 2007 article published in The Lancet called it "the operation of the century" due to its excellent results. According to guidelines for hip replacements in tertiary care hospitals in South Africa, 90–95% of all hip replacements will be usable after 10–15 years of use. In the process of prosthetics, the head of the femur is replaced with an artificial head equipped with a pin, and then inserted into the acetabulum. Partial replacement is also possible in the case of femoral neck fractures (mostly displaced), in which the entire femur, with the exception of the head, is replaced. Over the past decades, significant advances have been made in studying the characteristics of the hip joint, however, when considering the possibility of performing such operations, it is necessary to take into account the patient's age, his disease, possible dysfunction of the hip joint, level of physical activity and characteristics of fractures.

X-ray of total hip arthroplasty

Clinically Relevant Anatomy

The hip joint is a ball-in-socket joint. This means that the head of the femur, which is the “ball,” is located inside the acetabulum, the “socket.” This connection of the femur and pelvis allows for multi-axis movements of the hip. The acetabulum has the shape of a cup, inside which the head of the bone rotates with a fairly large degree of freedom. The head is enclosed by the acetabulum beyond its maximum diameter. The head and the inner surface of the cavity are covered with a thin layer of cartilaginous tissue. Once this layer is completely worn out or damaged (usually occurring with arthritis), the surfaces of the bones become highly sensitive to friction, leading to pain, decreased mobility, and possible shortening of the affected leg. Replacing these surfaces is aimed at eliminating pain and immobility, as well as returning the patient to the ability to lead an active life without physical discomfort.

Hip endoprostheses

All total models are standardly presented with a leg with a head and a cup with a polymer liner. The only distinguishing feature is the materials that were used in the friction pair. The following combinations of kinematic units exist:

metal-to-metal – an inexpensive friction pair with the lowest durability characteristics;
ceramics-polyethylene is an ideal combination that is most often used, since this model has amazing wear resistance, bioinertness, mobility, and its price is average;
ceramics-ceramics - leads in terms of abrasion resistance, and, therefore, is recognized as the most durable.

A completely ceramic friction pair is considered to be the most durable.

From left to right: metal-polyethylene, metal-polyethylene, ceramics-polyethylene, ceramics-ceramics.

Regardless of the models used for implantation, it is important to know that each of them can last quite a long time (20-25 years). However, how can you quickly fail if you were operated on by an inexperienced surgeon, or if errors were made in rehabilitation and lifestyle. Ceramic products are no exception. Remember, an operation performed at an exemplary level, high-quality rehabilitation, and strict adherence to a physical activity regime are the key to a long and excellent service for your new joint.

Epidemiology/Etiology

Total hip replacement is a frequently performed operation. Although it is performed in selected cases, it is also used for hip fractures (most often displaced fractures of the neck) caused by trauma (for example, a fall) or other pathological processes. Osteoporosis and osteomalacia are often the causes of hip fractures in older people. Arthritis, in its most common form, osteoarthritis, is also a common degenerative process among this population group. Because of the great success achieved in restoring function and mobility to those suffering from osteoarthritis, the total hip replacement procedure has become a common treatment for hip injuries. It is also used to treat juvenile rheumatoid arthritis, but only if other methods are unsuccessful.

Minimally invasive and classical techniques

Orthopedists use classical or minimally invasive access techniques. Minimally invasive technology is based on making a small incision through a posterolateral or anterolateral approach. The length of the incision does not exceed 8 cm. The advantages include minimal trauma, which allows for shorter rehabilitation times and less painful recovery. However, minimally invasive technology is not widespread today due to the fact that it complicates the operating process due to insufficient visualization of the working field.

The size of surgical incisions with classical and minimally invasive techniques.

Suture after minimally invasive hip surgery.

In order to perfectly process and prepare the bones, and then flawlessly place the prosthesis, it is necessary to sufficiently expose the hip region. This is facilitated by a large incision of about 15 cm.

Clinical picture

Hip fracture: The patient often cannot walk, complains of aching pain in the knee, hip, groin, back or buttock, and has difficulty carrying heavy objects. The damaged femur is shown in the x-ray below.

Femoral neck fracture

Osteoarthritis: Felt or audible crunching when moving, inability to assume an anatomically neutral position. Often accompanied by pain and/or limited movement. X-ray studies usually indicate a decrease in joint space, subchondral sclerosis, cyst formation and the appearance of osteophytes.

Osteoarthritis of the hip joint

Rheumatoid arthritis: Movement of the hip joint is difficult and associated with pain; after rest, stiffness in movements and pain reappear.

Avascular necrosis: Symptoms are similar to those of osteoarthritis, and knee pain is also felt.

Avascular necrosis

Where to get hip replacement in Moscow

Extensive experience in hip replacement in Moscow has been accumulated in the following medical institutions:

Central Research Institute of Traumatology and Orthopedics named after. N.N. Priorova;
Central Clinical Hospital of the Russian Academy of Sciences;
City Clinical Hospital named after S.P. Botkin;
Road Clinical Hospital named after. N.A. Semashko;
City Clinical Hospital No. 67 named after L.A. Vorokhobova.

Endoprosthetics are also carried out in other medical centers of the city, including a number of private clinics that provide the service.

Indications for surgery

Pain and loss of mobility are the most common complaints of patients requiring total hip replacement. In severe cases, despite conservative treatment, persistent pain, limited range of motion and night pain still occur. Previous problems with the hip joint are a significant sign of the need for total hip replacement. Complete replacement of the hip joint will be a good solution if difficulties arise with fixation of a femoral neck fracture, in particular when the articular cartilage of the acetabulum is completely worn out.

Femoral neck fractures caused by underlying pathologies such as Paget's disease in elderly patients are usually treated with total hip replacement. If the patient suffers from rapidly progressing severe hip disease, x-rays will show significant destruction of the femoral head or pubic ramus, indicating that the only possible solution here is a complete replacement of the hip joint.

Before prescribing a total hip replacement, it is important to take into account the patient's age, physical activity, expectations from the operation, and the diagnosis determined based on the X-ray examination. It is the surgeon, together with the patient, who decides whether hip replacement is the best solution. Various procedure prioritization rankings (eg New Zealand National Clinical Priority Score) can be used to assess the need for hip replacement. This method is often used to determine the urgency and expected results of a procedure in those medical centers where, due to limited resources, patients are forced to wait on a waiting list for surgery.

Common indications for surgery:

Osteoarthritis.
Post-traumatic arthritis.
Rheumatoid arthritis (including juvenile rheumatoid arthritis).
Avascular necrosis.
Failure to fix hip fractures.
Congenital hip dislocation and dysplasia.

Contraindications for surgery

Absolute contraindications

Progressive infection in the joint unless repeated surgery is performed as an immediate replacement or interval procedure.
Systemic infection or sepsis.
Neurogenic arthropathy.
Malignant tumors that prevent reliable fixation of components.

Relative contraindications

Localized infections, particularly in the chest and bladder, skin infections.
Absence or relative insufficiency of abductor muscles.
Progressive neurological disorders.
Any pathological processes that quickly destroy bone.
Dental or urological procedures required by the patient, in particular transurethral resection, must be performed before complete replacement of the hip joint.

Possible complications

The main ones include:

external, internal infectious pathogenesis (local);
painful syndrome (in the early period this is the norm);
pulmonary embolism (for prevention, anticoagulant drugs and early exercise therapy are prescribed);
damage, breakdown of the endoprosthesis (usually a consequence of injury);
dislocation, subluxation of the implant head (mainly due to incorrect motor mode or initially poor-quality installation of the prosthesis).

Dislocation of the femoral component.

The highest percentage of all known complications is infection. It develops with poor care of the surgical wound, the presence of any active infection in the body, or due to non-compliance with aseptic and antiseptic standards in the operating room.

Discharge from a wound? See a doctor immediately.

To prevent the development of an infectious focus, patients are prescribed a course of antibiotic therapy. If pathogenesis does occur, long-term and intensive anti-infective treatment will be required, and in advanced situations, repeated surgery.

The implant can break, but this happens very rarely.

Dislocations and subluxations are treated, depending on the severity of the clinical picture, by conservative or surgical reduction of the head into the acetabular element.

Diagnostics

Diagnosis of patients requiring total hip replacement is carried out mainly on the basis of existing symptoms. Pain, decreased range of motion, and dysfunction are the most common. For patients complaining of hip pain, it is also necessary to carry out a comprehensive differential diagnosis, because often it can indicate diseases of the spine and pelvis, but have no connection with the hip joint. The surgeon must lead the diagnostic process and its organization.

Read about examination of patients with hip joint problems here.

The consultation with the surgeon should include the following elements:

Observation.
Patient interview:
Complaints of pain, deformity, stiffness and/or lameness.
Previous diseases associated with hip pain (congenital or childhood diseases, past injuries).
Physical examination:
In a standing position.
Trendelenburg test.
While walking.
Lying on your back (including measuring leg length).
Objective observation (posture, deformities, muscle atrophy).
Assessment of range of motion.

Special research methods

X-ray examination. This method is used primarily, and in most cases only X-ray examination is necessary, since it is this that makes it possible to make a large number of diagnoses when there is a need to replace the hip joint. Its results will determine the need for further research.
Other methods: computed tomography, magnetic resonance imaging.

Anesthesia

General anesthesia causes reversible depression of the central nervous system with temporary loss of consciousness and suppression of pain sensitivity, which will allow you to feel absolutely nothing during the procedure. This type of pain relief is used in rare situations, for example, if the mental state is unbalanced. Of 100% of interventions performed, only 8%-10% are performed under full anesthesia.

Approximately 90% of operations are performed under regional anesthesia. The person is conscious, but he does not feel the lower part of the body at all. This type of anesthesia can be epidural or spinal.

An anesthetic is injected through a catheter system into the epidural space of the spine. Spinal anesthesia involves performing an injection through a thin needle into the spinal fluid located in the subarachnoid space of the spine. Both types of regional anesthesia completely “turn off” pain sensitivity in the lower extremities.

Surgery

Surgical approaches

Anterior approach (Smith-Petersen).
Antero-external approach (Watson-Jones).
Direct lateral approach (Hardinge/Transgluteal).
Lateral transtrochanteric access.
Lateral access.
Posterolateral approach.
Posterior access (Moore/Southern).
Minimally invasive approaches (eg direct anterior approach).

A large number of surgical approaches for hip replacement have been described, but we will focus on the anterior, lateral and posterior approaches. These options allow you to determine the extent of soft tissue damage and the basic precautions required when performing total hip replacement. The posterior approach is the most popular for hip arthroplasty. This method provides a good view of the femur and acetabulum and also avoids damage to the hip abductor muscle groups. The anterior approach is less invasive and causes less damage to muscles, capsules, ligaments and nerves. Research also demonstrates faster rehabilitation and greater restoration of functionality. Due to the lower risk of dislocation compared to the posterior approach, early mobilization and weight-bearing exercises with proper weight bearing can be performed within the first few days after surgery. The use of minimally invasive surgery is gaining popularity around the world due to the high rate of recovery of the body and significantly fewer complications. However, long-term consistent and comparative studies are still needed in this area.

Hip prostheses

Hip prosthesis

Joint prostheses used by surgeons are made in the concepts of “metal on polyethylene (PE)”, “ceramics on PE”, “metal on metal” and “ceramics on ceramics”. Important characteristics of prostheses are the coefficient of friction, durability, resistance to dislocation and the degree of fixation in bone tissue. In some cases, osteonecrosis may develop due to erosion of the prosthesis components caused by their friction against each other. Recent research shows that PE containing vitamin E wears 95% less than other materials used to make an artificial acetabular cup.

Complications

From 2 to 10 percent of patients develop complications during and after a total hip replacement. The following cases are most often described in the literature and observed in clinical practice:

Dislocation: The anterior approach reduces the risk of dislocation compared with the direct posterior approach.
Abductor insufficiency: Most common after direct lateral approach.
Intraoperative fractures.
Nerve damage (depending on access).
Direct lateral approach – superior gluteal and femoral nerves.
Direct anterior approach – femoral cutaneous nerve.
Posterior approach – sciatic nerve.
Wound infection and/or sepsis.
Deep vein thrombosis or pulmonary embolism.
Metallosis. This complication occurs when the metal corrodes and its particles spread. It leads to a large local release of cytokines followed by inflammation. Systematic exposure to metallosis can lead to many negative consequences. The only possible treatment is re-prosthetics.
Atelectasis.
Lower respiratory tract infection.
Relative change in leg length.
Loss of prosthesis fixation and implant wear.

Fixation of the endoprosthesis

How is the endoprosthesis fixed? Parts are secured using one of three methods of fixation:

Cement - used more often in old age, if the patient has some degree of osteoporosis in all prosthetic areas. Medical cement, which hardens in 10 minutes, strengthens fragile structures and firmly connects the non-native hip joint to them.
Cementless – involves tightly hammering the femoral and acetabular element into the bone structures using the “press-fit” technology.
Combined – the feasibility of this method arises when one of the bones has signs of osteoporosis, and the other is in good condition. The corresponding part of the endoprosthesis is fixed to the problematic bone using bone cement. Fixation with healthy bone is done using the “press-fit” method.

The surface of the implants is rough; over time, bone structures will grow into it.

The part of the prosthesis that will be attached to the bone differs in texture for cemented and cementless models. For implants that are seated on medical cement, it is perfectly smooth. In cementless ones, it is grooved, due to which such a surface is densely overgrown with natural bone after a certain period of time.

Fiction scheme.

Physical therapy

Friends, this and other questions will be discussed in detail at the seminar “Physical rehabilitation after hip and knee joint replacement.” Find out more...

Precautions and contraindications

Patients are at risk for hip dislocation after hip replacement if the joint stabilizers (capsules, ligaments, and muscles) have been injured or due to different sizes of the prosthesis and bones. The smaller size of the artificial femoral head in comparison with the human femoral head facilitates easier dislocation of the former until the stabilizing tissues are completely restored and adapt to the smaller dimensions of the head. This recovery usually takes 6 weeks.

Rear access

The following movements of the hip on the operated side are prohibited:
Flexion greater than 90 degrees.
Internal rotation beyond neutral position.
Adduction of the hip beyond the midline.
Limitations on the load on the leg as directed by the surgeon (gradual transition to full load on the leg within 6 weeks after surgery).

Anterior approach

Replacement of the hip joint with this approach proceeds more smoothly. There are no specific prohibited movement limits for this approach, as they are determined largely by surgeon preference.

Patients are advised to avoid a) excessive amplitudes and b) combinations of the following movements of the hip on the operated side:

Extension.
Lead.
External rotation.

Weight-bearing restrictions as directed by the surgeon (usually less stringent than with the posterior approach; patients can/are allowed to ambulate much earlier).

Preoperative preparation

Prescribing preoperative exercise after prosthetics has been prescribed can play an important role in improving the patient's condition before surgery, because the wait for it to be carried out can drag on for many months and lead to further deterioration of health. Level 2B evidence suggests that physical and educational therapies may be effective for advanced osteoarthritis. A study of a six-week education and training program reported significant, sustained success in relieving pain and dysfunction in patients waiting for joint arthroplasty surgery. Further positive results also include progress in functional, educational and psychosocial aspects.

Rehabilitation after hip replacement

Rehabilitation should be inseparable from surgery. The entire recovery process is divided into three periods:

from the end of the operation to discharge from the hospital – 15-20 days;
up to 2-3 months after the intervention;
up to 1 year after endoprosthetics.

Each of the time periods has its own goals, the implementation of which, at least at first, should be carried out by the patient under the strict guidance of medical personnel. The main objectives of rehabilitation are as follows:

prevention of postoperative complications;
normalization of the condition of the uneven muscular system of the leg;
achieving the maximum possible range of motion in the joint;
general strengthening of the musculoskeletal system;
formation of the correct approach, balance and stability during movement and static loads;
adaptation of the patient to everyday life.

A routine examination by an orthopedist is required at 3, 6 and 12 months after the intervention. If alarming symptoms occur, the patient should immediately contact the doctor who performed the operation.