The hip joint is the second most large and weight-bearing joint in the human, it consists of a fixed part which is the pelvic bone, and the articulating part which is the head of the thigh bone. Doctors at some point in the 19th century figured out that some hip joint pain can’t be relieved by medications only, so they innovated joint replacement surgeries.
What is hip arthroplasty?
Hip replacement surgery which is called hip arthroplasty is one of the most performed surgeries nowadays. There are two major types of hip arthroplasty; partial and total removal of the hip joint and replacing the diseased parts with a prosthesis. Hip arthroplasty took a rising curve of modifications since the 20th century including its technique, equipment, and the material used in the implants.
It is believed that Sir John Charnley pioneered hip arthroplasty in the 1960s as he managed to perform successfully the first total hip arthroplasty which was a breakthrough. Charnley exerted great effort in refining the biomechanics of hip arthroplasty as he developed the principle of low-frictional torque in hip replacement surgery which reduced the possibility of long-term complications of the prosthesis.
Pros and cons
hip arthroplasty is a well-known surgery to the medical community for its remarkable results, it is estimated to be performed for more than 450,000 patients every year in the United States. It is believed that more than 2.5 million people are living with artificial hips in the US. A statical study has shown that hip replacement surgery is one of the most successful surgeries as it has a success rate of more than 95% and rising due to different adjustments and modifications.
Recent studies have revealed that hip arthroplasty not only improves the quality of life but also it extends life span by preventing complications of recumbence. Patients who underwent hip arthroplasty usually don’t report any unexpected results after surgery. however, hip arthroplasty has a mortality rate. Fortunately, the mortality rate of hip replacement is neglectable and documented to be 0.6% within 90 days after surgery.
No doubt that life expectancy and quality of life significantly improve after hip arthroplasty, yet both are subjected to the general health condition, age, and outcome of surgery. Correlation between hip replacement and life expectancy was provided by a ten-year study which revealed that patients aged less than 65 have an 89% survival rate for 10 years after surgery. it is also found that the ten-year survival rate gradually decreases as patients’ age increases.
⇒ Now, let’s discuss hip replacement indications.
Indications of hip replacement surgery
Orthopedic doctors select patients to have hip arthroplasty based on the severity of the condition in addition to radiographic evidence of joint destruction. Patients eligible to have hip replacement surgery usually suffer from joint pain, limitation of movement, stiffness, and deformities. Unfortunately, different diseases involve joint affection, and most of them are associated with joint destruction. We will summarize the most common disorders that may lead to hip arthroplasty.
- Rheumatoid arthritis (RA) is an auto-immune disorder in which patients’ immune cells attack joint synovium (the layer lining joint surfaces) causing inflammation. The inflammatory process subsides by early treatment with anti-inflammatories otherwise joint damage becomes irreversible. RA usually spare large joint first. However, an atypical course of rheumatoid arthritis occurs affecting the hip joint.
- Osteoarthritis is an inflammation of bone and joints. many orthopedic doctors believe that osteoarthritis is a degenerative disorder affecting weight-bearing joints such as knee and hip joints due to aging. Negligence or bad management of osteoarthritis leads to gradual deterioration of joint mobility and severe joint pain that may indicate joint arthroplasty. Osteoarthritis is considered the most common disorder that may eventually lead to hip arthroplasty as it contributes to more than 60% of the performed surgeries.
- Bone or cartilage tumors invading the head of the femur (thigh bone) or acetabulum are an indication for hip replacement surgery. although primary bone tumors aren’t common, secondary tumors developing from circulating metastasis are common.
- Severe trauma causing multiple fractures especially comminuted fracture to pelvic bone or femur may result in an inability for bone fixation, therefore hip arthroplasty is indicated.
- Osteonecrosis is a medical term that means the death of bone tissue. The definitive cause of osteonecrosis is still debatable, but it is most likely due to interrupted blood supply. Patients with osteonecrosis in their hip joint often presented with dull ache pain in the pelvic area. Unlike other bone diseases, osteonecrosis is better diagnosed with MRI.
Late and untreated cases of osteonecrosis result in reducing bone density and finally collapse. Unfortunately, symptomatic treatment is the only non-invasive treatment available for osteonecrosis. The most reliable pain-relieving procedure for patients with osteonecrosis is joint replacement surgery.
Contraindications of hip replacement surgery
Contraindications of hip arthroplasty aren’t much and include:
- Untreated underlying disease that caused hip joint destruction and deformity.
- Ongoing active infection whether it affects the hip joint or not because the injury of blood vessels during surgery may increase the risk of spreading the infection.
- A progressive neurological disorder that may affect the ability of the patient to use his hip joint.
- Terminal malignancies are believed to be better treated with potent analgesics other than surgeries.
Patients’ eligibility
Doctors examine patients carefully and look for any potential foci of infection in the hip or the surrounding structures before hip arthroplasty. patients with active infection must have their surgery postponed till getting cured. patients’ neurological status, as well as their musculoskeletal system, should be evaluated for proper selection of surgery and to avoid complications.
If both hip joints are indicated to get surgically replaced, the more painful side is replaced first then the other joint is replaced after 3 months. The pre-operative assessment report which is usually enclosed with radiographic images is crucially important for predicting the outcome of the surgery and for medico-legal aspects.
Types of hip replacement surgery
What are the types of hip replacement surgeries? Hip replacement surgeries are classified according to how far the joint parts are going to be replaced. Orthopedic surgeons classify hip arthroplasty furthermore according to the technique of the procedure. Partial and total hip arthroplasty which are the most common types of hip replacement surgery will be discussed separately.
1- Total hip replacement (THR) is a surgical procedure in which both the femur head and the socket of pelvic bone are replaced with a prosthesis. THR is major surgery with a high success rate as it restores joint smooth articulation and mobility. An anesthesiologist prepares patients going to have THR by giving them general or regional anesthesia to block sensations from the lower half of their body.
Orthopedic surgeons start by making an 8 – 15 cm incision in the posterior-lateral side of the side. Anterior thigh incision isn’t preferred because it gives the surgeon limited access to the hip joint making the surgery a bit challenging. The surgeon separates the fascia and muscles covering the hip joint then dislocates the femur (thigh bone) from the pelvic bone and excises the femur head with a power saw. Then the acetabulum (the pelvic socket) is removed by a special drill forming a hemispherical cavity in which the artificial pelvic part will be placed.
Finally, the surgeon inserts a femoral stem in the thigh bone which acts as a pillar for which the femoral head will get attached. The acetabular part of the prosthesis is also placed in the pelvic bone to act as a socket for the femoral head. The two components of the prosthesis should perfectly fit each other to provide the full range of motion. The surgery usually takes about 60 – 90 minutes.
2- Partial hip replacement is a surgical procedure in which the femoral head is replaced with an artificial implant with sparing of the pelvic bone, so it is called hemiarthroplasty. Fracture of the thigh bone due to trauma or osteoporosis is the main cause of hemiarthroplasty. Partial hip replacement is less commonly performed than THA. it is believed that prosthetic implants of THA are less stable and more liable for dislocation than those of hemiarthroplasty.
Patients who are going to have hemiarthroplasty should undergo the same pre-operative examination of THA, moreover, the size of the femoral implant should be selected to fit the socket of the pelvic bone. partial hip arthroplasty goes in the same manner as done in total hip arthroplasty except remodeling the pelvic component. Surgeons test the smoothness of motion of the prosthesis with the pelvic bone by the passive articulation of the joint during the operation.
Materials of prosthesis
materials used in the hip prosthetic implant are various and differ in their durability and coefficient of friction. Orthopedic doctors select the most suitable material of the implant for each patient according to their occupation, activity, age, bone condition, and surgeon’s preference. It is important for patients who are going to have hip arthroplasty to discuss their options of the implant material that fits their needs.
Prosthetic implants nowadays are mainly made from ceramic, plastic, polymers, and metals. Although each material has its pros and cons, they are all effective, bearing, and have long-lasting durability. Metal implants are made of corrosion-resistant titanium alloys, and they are less expensive than other materials, yet they contain cobalt, chromium ad nickel that may cause an undesired reaction for some people. It is believed that ceramic on plastic is the most wear-resistant and commonly used material in hip prosthetic implants. The eroded and unstable thigh bone is better to be affixed with the prosthetic implant using cement while healthy bone gets porous implant through which bone grows and adheres.
Complications
Complications of hip arthroplasty aren’t common but like any major surgery, there is a possible risk of them happening during or after the operation. Nerve, visceral and vascular injuries may occur during surgery due to the surgeon’s incompetence or lack of experience. a blood clot is an early complication that may circulate in the bloodstream forming embolisms that spread to other organs. Thrombo-embolic complications are found to be the most common cause of death within 3 months after hip arthroplasty.
Catching Infection during surgery isn’t usually reported due to effective sanitary procedures unless the patient is immune-compromised, or the surgery is done under a low standard of sanitation. Improper selection of the prosthetic implant may cause its loosening, dislocation, leg length inequality, and limited range of motion. Fortunately, most of these complications are avoidable by simple prophylactic measures such as antibiotics and blood thinners.
Fees of hip replacement surgery
Fees of hip arthroplasty vary in a wide range of 10,000 – 100,000 US dollars worldwide. Medical facilities in the United States of America are found to charge higher than anywhere else for hip arthroplasty followed by west Europe. The average cost of hip replacement surgery in the US starts from 35,000 without insurance. Hip arthroplasty may be considered an over-priced surgery. however, a prosthetic implant only may cost 10,000 US dollars.
There are medical facilities in different countries that provide hip arthroplasty with considerably lower fees. Turkey, Mexico, Egypt, and Singapore which provide excellent medical care have average fees of 15,000 US dollars for hip arthroplasty. Indian hospitals cost the least for hip replacement surgeries starting from 6,000 US dollars. Patients who are going to have hip arthroplasty should financially consider their options and how much will their health insurance cover the fees of the surgery.
Recovery and rehabilitation
Patients should stay in the hospital for 1-2 days after their hip replacement surgery to be observed. After getting discharged from the hospital, patients should visit their orthopedic doctor for at least a month to follow up on their progression and recovery process. Orthopedic doctors usually give post-operative instructions that include avoiding exerting much effort or bending their hip joint more than 90 degrees until they make sure it’s fully healed. Patients are also asked to keep their incision area as clean as possible to avoid infections.
Patients get referred to a rehabilitation unit by their orthopedic doctor to regain their muscle strength and mobility. The rehabilitation phase hasn’t a certain duration, but it differs from one person to another according to their progression. Physical therapy is also recommended for these patients as they are asked to do simple exercises with increasing their intensity gradually to strengthen muscles of the lower limb.