Hip replacement is a surgical operation in which the hip joint is replaced with a prosthetic one. Hip replacement surgery is also known as hip arthroplasty, and it is one of the most performed procedures in orthopedic surgeries with high success rate. In a study by Soderman P et al. to study the long-term outcomes after hip arthroplasty surgery. They founded that hip replacement surgery success rate was more than 90% after more than ten years following the procedure.
Over years, the number of replaced hip joints per year are increasing. One million arthroplasties are done every year, and the numbered were doubled in twenty years. According to centers for diseases control and prevention, there were more than 234,000 total hip arthroplasty surgery in 2004.
Hip replacement surgery means changing the whole joint in a surgery known as total hip replacement surgery, while changing only the femoral head of femur in a procedure known as hemiarthroplasty surgery.
Hip replacement surgery can relieve patient’s pain, improving his mobility, daily activity, and the patient quality of life. Hip arthroplasty surgery have good prognosis for many years following the procedure.
Preoperative preparation of the patient
When patient with severe hip joint arthritis and pain interfere with his daily activity seeks treatment, the American academy of orthopedic surgeons recommends that all patients should be put on medical treatment and physical therapy modalities as first line treatment before shifting to surgery. Non-surgical interventions that can be tried first:
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- Non-steroidal anti-inflammatory medications
- Encouraging the patient to lose weight
- Physical therapy
- Corticosteroid therapy either by local injection or oral steroids under medical supervision
Preoperative patient assessment
For all patients, a full detailed history and a complete physical examination is mandatory for preparation the patient for his surgical procedure.
〉History
A full detailed history about the patient hip condition, and if he undergo any previous surgery in that hip joint. The surgeon may ask about any previous implant in any other joint in the body.
A full medical history of the patient including any chronic conditions such as diabetes mellitus, hypertension, thyroid diseases etc.
〉Physical examination
The surgeon should examine not only the hip joint, but all the patient’s joints. Assess patient’s spine and knee joint conditions before hip arthroplasty surgery. Leg length discrepancy must be excluded before the surgery as it may affect the outcome of the procedure. Range of motion of the affected hip joint must be evaluated before the surgery.
〉Imaging
All patients should have pelvis view with x-ray as these images help to identify the deformity and its extension
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- Standing anteroposterior x-ray pelvic view of the affected hip joint
- Lateral view of the affected hip joint
In some patients MRI images may be needed to assess the condition of the bone and surrounding soft tissues.
Contraindications of hip replacement surgery
The choice of patients that are candidate to the hip arthroplasty is particularly important. Some situations and conditions may interfere with the success of the surgery. so, there are a few contraindications for a patient to undergo a hip arthroplasty surgery such as:
Infection: the infection is one of the most important contraindications for hip arthroplasties, and any patient with ongoing infection is an absolute contraindication to the surgery.
Smoking: heavy smoking results in increasing the risk of post-surgical complications in hip replacement surgery. In a study by Kapedia et al. founded that smoker who underwent total hip arthroplasty surgery have more post-surgical complications than non-smokers. In the same study, they founded that, smokers were more likely to undergo a revisit surgery than non-smokers. All patients that may undergo a hip arthroplasty surgery are advised to stop smoking before the surgery.
Osteoporosis: it is a medical condition that results in fragile and weak bones and raises the patient’s risk to break a bone. In a study by Botti et al. to study the role of bone metabolism effect on patients with osteoporosis who undergo a hip arthroplasty surgery. At the end of the study, they founded that mild cases of osteoporosis can undergo the surgery after proper assessment and evaluation of their condition, while more severe cases may benefit from delaying the procedure and pursuit in osteoporosis medical treatment first. In the same study they founded that, bisphosphonates can improve post-surgical outcome. Patients with osteoporosis have multiple complications in case of undergoing hip arthroplasty surgery, these complications include:
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- A fracture that may happen before the scheduled surgery
- Increase the risk of intra-operative fracture
- Osteoporosis may cause post-operative loosening of the joint
Miscellaneous: other contraindications include chronic alcoholism, severe cases of vascular insufficiency, and patients with poor mental state as in Alzheimer, and dementia.
Preparing for the procedure
Before the surgery, the patient should be examined and the physician should check his vital signs such as blood pressure, random blood sugar. If the patient has any chronic diseases such as chronic heart diseases, or chronic kidney or liver diseases, the surgeon must communicate with the treating physician to make sure that the patient condition is stable, and he is liable to surgery.
The patient medication should be evaluated by his physician to assess which medications should be stopped before the surgery such as aspirin or change the dose such as insulin.
Routine blood tests before the hip arthroplasty surgery include:
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- Complete blood picture
- Random blood sugar
- If diabetic, HBA1C should be obtained before the surgery
- Kidney function tests
- Liver function tests
- Urine analysis
- Coagulation profile
Other routine tests include:
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- Electrocardiogram
- Echocardiogram
- Pelvi Abdominal ultrasound
Surgeons usually encourage the patients to lose weight before hip arthroplasty surgery for better postoperative outcomes.
Home adjustments and installments are used to pave the home for the post-operative recovery phase. For example:
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- Secure safety bars in the bathroom
- Install a handrail in the side of stairs
- Adjustable toilet seat
- Any movable object or carpet that can cause patient to fall should be removed
The procedure
Hip replacement surgery is a common orthopedic solution for a damaged malfunction hip joint. There is different type of hip replacement surgeries.
Total hip replacement surgery
In total hip replacement surgery, the damaged joint components (bones and cartilage) are replaced with prosthetic joint.
Hemiarthroplasty surgery
In hemiarthroplasty surgery, half of the hip joint is removed; the femur head is removed, and suitable prosthesis is implanted in place.
Bipolar hip hemiarthroplasty surgery
In this type, the femur head is replaced with a prosthetic that stabilize the femur head to the acetabulum and help in restoration of hip joint function and mobility.
Approaches of the hip replacement surgery
Hip arthroplasty have different approaches, each has pros and cons. Each surgeons use the most suitable approach for every patient, and what he prefers and experienced at. These approaches or techniques are named according to their relation to Gluteus Medius muscle.
1- Posterior approach
Posterior approach is one of the most common techniques used in hip arthroplasty surgery. In this approach the surgeon access from the back of Gluteus Medius muscle.
Advantages of this approach include:
- Provide good exposure to the joint structure
- This procedure does not cause an injury to the hip abductor muscles, so this may help to decrease post-operative abductor muscles dysfunction
- Recent studies suggests that posterior approach decrease the rate of nerve injury during the procedure
Disadvantage of this approach include:
- Posterior approach carries a higher risk of post-operative dislocation of hip joint
2- Direct anterior approach
In this approach, the surgeon enters the joint between the tensor fascia latta and Sartorius muscle. Dr Joel Matta and Dr Bert Thomas adopted this approach because it showed promising results regarding post-operative hip dislocation, but with modern techniques, and new implant shapes, dislocation rates are now comparable between anterior and posterior approaches.
According to a study by Maratt JD et al., no difference in hip dislocation rates were noted between anterior and posterior approaches in total hip arthroplasty surgery.
Advantages of this approach include:
- Improve the post-operative functional ability of the hip joint
Disadvantages of this approach include:
- Loosening of femoral component of the hip joint
- Early revision surgery in comparison to other approaches
- Increases rate of wound complications
- Femoral exposure is difficult than posterior technique
- Increase the risk of lateral femoral nerve injury (LFCN)
3- lateral approach & Anterolateral approach
it is a common approach in hip arthroplasty surgery, but it is not preferred because the abductors muscles do not heal properly after the surgery, leading to post operative chronic pain and weakness in the hip abductors muscle.
It is one of he least used approaches in hip arthroplasty; this is due to it causes damage to hip joint abductors.
4- Minimally invasive technique
Beside all the previous techniques, a hip arthroplasty by using minimal invasive technique is used frequently by surgeons. In this technique, the surgeon uses the conventional approach e.g., anterior, or posterior approaches, but with small wound incisions.
No definitive data about superiority of any approach to others, and the choice of specific technique relies of the surgeon preferences and experiences.
In a study by Kennon et al. about hip arthroplasty surgery with direct anterior approach, and minimally invasive technique. They founded that after following up with one hundred patients, there were three complications that were reported:
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- One case reported proximal femur fracture
- One case reported acetabular perforation
- One case with deep infection
In Mardones et al. study about minimal skin invasion technique via posterior approach of hip arthroplasty in a cadaveric study. They founded that, the injury of Gluteus Medius, and Gluteus Minimus muscles were less than in hip arthroplasty surgery via posterior approach without minimal invasion technique.
Post-operative care
After the procedure, a good care to the wound is mandatory for appropriate wound healing, and closure. The patient would be advised about how to seat, and how to put him self in and out of a bed, or a chair. Patient would be educated about appropriate hip flexion, and how to proceed in his daily activity slowly and under surgeon instructions.
Post-operative deep venous thrombosis is a quite common post-surgical complication. since the patient’s mobility would be limited following the hip arthroplasty surgery, prophylaxis treatment immediately after the surgery is important.
A study by Raphael et al. about the use of aspirin as a prophylaxis after arthroplasty. They founded that aspirin using after hip arthroplasty has a beneficial effect on prevention post-operative deep venous thrombosis and pulmonary embolism.
Complication of hip replacement surgery
Hip arthroplasty, either total or hemiarthroplasty are major surgeries that carries a risk of post-operative complications.
Hip dislocation
Post-operative hip dislocation is one of the major complications following hip arthroplasty surgery. Hip dislocation could be early-onset, or late-onset dislocation with different etiologies. There are multiple factors that can predispose to post-operative hip joint dislocation. From these factors:
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- Previous hip surgery
- The design of the prosthetic is not suitable or was badly positioned
- Some approaches have a higher risk of developing hip dislocation more than others
Late-onset dislocation usually occurs after five years from the hip arthroplasty, old age is one of the predisposing factors for late onset dislocation. A study by Von Knoch et al. to study late-onset hip dislocation after hip arthroplasty. They founded that 616 hip dislocation cases were reported from 25,465 cases of hip arthroplasty surgery. From these cases 0.6% were late-onset hip dislocation cases. The researchers founded some factors that can be linked to late-onset dislocations such as:
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- Recurrent subluxation
- Hip trauma
- Acetabular malposition
Late- onset dislocation could be prevented by regular follow up for assessment and evaluation of the patient’s condition, and if there are any symptoms of impending dislocation.
Early-onset dislocation is the most common early complication following hip arthroplasty. It usually occurs within three months of the surgery. it is a leading cause for early revisit of total hip replacement. The etiology of early-onset dislocation is usually multifactorial. From these factors:
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- Soft tissue instability
- Malposition of joint component
- Patient position was incorrect
Early-onset dislocation usually does not necessitate any surgical intervention to reposition it. There are multiple risk factors that are linked to early-onset dislocation such as:
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- Old age is a major risk factor
- Females are prone to hip dislocation more than males
- A few conditions are linked to increase risk of early onset dislocation as muscular dystrophy, Parkinson’s disease, and cerebral palsy
Deep venous thrombosis
Venous thrombosis is a common post-operative complication following hip arthroplasty and may pose a life-threatening condition such as pulmonary embolism. Every patient undergo hip arthroplasty would receive a prophylaxis treatment of deep venous thrombosis as a routine precaution following the surgery. There are specific measures that can lower the risk of post-operative DVT, and pulmonary embolism as:
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- Medical treatment with LMWH or aspirin
- Epidural anesthesia
- Physical therapy following the procedure
A study by Valle et al. followed 989 patients who underwent a total hip arthroplasty. Those patients received a single dose of unfractionated heparin intraoperatively, and additional treatment with aspirin in 87% of patients, and warfarin in 13% of patients. In those patients asymptomatic DVT occurs in 7.1% of patients, while symptomatic DVT occurs in 0.88% of patients.
Hip arthroplasty periprosthetic fractures
Recently, the incidence of hip arthroplasty intraoperative fractures is increasing. This is due to increase the rate of hip arthroplasty surgeries in young adults. Intraoperative fractures commonly occur in femur and acetabulum.
Infection
It is one of the common complications of hip arthroplasty. The risk of infection is associated with specific risk factors such as heavy smoking, diabetes mellitus, and immunocompromised patients. Infection is a major risk factor for revision of hip arthroplasty surgery.
Limb length inequality
After total hip arthroplasty, a few patients may feel a discrepancy between the two legs. The leg may falsely seem longer after the surgery. the chronic arthritis in some patients prior to the surgery may lead to hip joint contractures following the surgery. this may appear as discrepancy in leg length. Post-surgical rehabilitation and restoring the joint mobility would lessen the situation gradually. Factors associated with limb-length discrepancy include:
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- Weakness of abductor muscles
- Pelvic inequality
- Hip joint lengthening during operation
Complications of the surgical wound
The surgical wound needs extreme care to prevent its complications such as sutures infection as cellulitis, delayed wound healing, and deep infection at the site of the surgery that may lead to severe skin necrosis.
Other complications may include iliopsoas impingement, nervous and vascular injury, and heterotrophic ossification.
Post-operative rehabilitation
It is important part in the process of healing following hip arthroplasty surgery. it includes managing patient comorbidities, pain, and any other problem that may face the patient in post-operative healing time.
Post-operative nutrition
Postoperative good nutrition and hydration have a profound impact on recovery, healing, and enable the patient to participate in rehabilitation schedules. Old age patients are more prone to be malnourished. This is due to patient immobilization after the surgical procedure, or due to age-related cognitive dysfunction.
Old age populations are at risk of being dehydrated after the surgery. This may cause later renal or metabolic problems.
Managing postoperative pain
In postoperative phase, managing pain is very crucial. Patients following hip arthroplasty surgery may have moderate to severe pain. So, appropriate pain control is necessary. Analgesia should be given on a regular schedule especially in the first days, and in the time of daily exercises. Long-acting narcotics can give a long-term pain free time in specific cases, but side effects should be kept in mind when prescribing narcotic analgesia. Old age patients are more prone to side effects. So, analgesic in this age group should be kept under monitoring.
Managing post-operative constipation
Constipation is one of the most common post-operative complications. post-operative constipation has many causes such as:
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- Due to patient immobility following the surgery
- Due to the possible effect of anesthesia
- As a side effect for long use of analgesia especially narcotic analgesia
Constipation must be treated promptly when the patient is symptomatic, as it may lead to nausea, vomiting, and intestinal obstruction. Treatment of post-operative constipation include stool softeners, laxatives, and in some cases an anal enema may relief the patient’s constipation.
Managing patient comorbidities
Patients with other chronic diseases or co-morbidities should be identified and monitored closely. Some conditions such as obesity and smoking may increase the risk of post operative complications. A study by Pritchard et al. founded that hospital discharge after total hip arthroplasty was delayed in obese patients and smokers.
Precaution for preventing hip dislocation
For all patients in rehabilitation programs following hip replacement surgery, there are some advices to help decrease the rate of hip dislocation. From these advices:
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- The patient would be advised not to cross his legs
- When lying on one side, put a pillow between your legs
- The patient would be advised not to put his legs in inward positions
- The patient is instructed to sit on elevated chairs, and not to bend over from the hip
- Some patients may need to use hip abductors brace for a while after hip arthroplasty surgery
- For some patients, some weight bearing exercises are restricted