Are complications the most important reason for the outcome after artificial hip replacement?
Total hip arthroplasty was one of the great advances in the history of medicine in the 20th century and has relieved the pain of many patients. With the improvement of the surgical technique, the improvement of the prosthesis involved and the advancement of materials, this surgery is now quite successful, however, complications can occur that can seriously affect the outcome of the surgery, such as infection, fracture, unequal length of both lower limbs, etc. Moreover, doctors and patients are now demanding ever-increasing surgical results, hoping to obtain the best possible function with minimal pain and precise surgery, and especially hoping for the longest possible life span, so that a single operation will last a lifetime. If late loosening and revision are included in the complications, it can be said that complications are the most important cause of postoperative outcome. If hip replacement complications can be prevented, the surgery is usually largely successful. Therefore, the prevention and treatment of post-operative complications after hip replacement remains a very important task.
What are the complications after total hip replacement?
Some complications after total hip replacement are unique to the procedure, and some are common to any major surgery in the elderly. Complications specific to total hip replacement include neurovascular injury, peripheral organ injury, bleeding and hematoma, limb inequality, postoperative joint instability and dislocation, heterotopic ossification, thromboembolism, fracture, late loosening, infection, osteolysis, and prosthetic stem fracture.Clohisy et al. reviewed the causes of revision in hip revision patients between 1996 and 2003 and found that aseptic loosening accounted for 55 percent, instability 14 percent, infection 7 percent, periprosthetic fracture 5 percent, and prosthetic fracture 1 percent. Among them, aseptic loosening is the most important cause of revision. Some of these complications can seriously affect postoperative function, such as fracture, dislocation, and infection, while others may endanger the patient’s life, such as pulmonary embolism due to thromboembolism. The occurrence of many complications can be prevented, and many of them are related to the technical level of the surgeon, so clinicians should strive to improve their knowledge and technical level to minimize the occurrence of complications.
What systemic complications should I be aware of during the perioperative period of total hip replacement?
Like other major surgeries, total hip arthroplasty can cause systemic complications, which can sometimes endanger the patient’s life. Commonly, such as peptic stress ulcers, postoperative gastric mucosal protective agents, such as omeprazole, should be given, and fecal occult blood tests should be performed if necessary. Myocardial infarction and heart failure are the most common life-threatening complications, and a detailed preoperative assessment of previous cardiac history and current cardiac status should be performed to avoid the occurrence of hypoxia and sudden increases and decreases in blood volume during surgery. Local placement of bone cement usually causes blood pressure fluctuations and occasional reports of arrhythmias and cardiac arrest, so fluid infusion should be accelerated to raise blood pressure while bone cement is being placed. Central venous pressure monitoring is performed if necessary. Fat embolism is not uncommon and is mostly transient, but in severe cases it can cause respiratory failure and lead to patient death. This complication should be considered and the appropriate department consulted if there is a postoperative decrease in oxygen saturation. Pulmonary embolism due to thromboembolism can lead to death within a short period of time and should be prevented. The average mortality rate of total hip replacement is about 1%, mostly due to the above-mentioned systemic complications. Therefore, careful preoperative evaluation is necessary to avoid the above-mentioned complications by comprehensive evaluation of the surgical risk according to the ASA score. Our hospital has a comprehensive preoperative preparation program for these complications, and as a result, there are very few perioperative deaths (no more than 1 in 1,000) for joint replacement each year, and no deaths occurred in the last year.
What are the causes of sciatic nerve injury during hip arthroplasty?
Sciatic nerve injury after total hip replacement is related to the anatomical changes in the nerve and the complexity of the reconstructive surgery. Risk factors include revision surgery, limb lengthening, and obesity. Surgical access is not associated with nerve injury. The sciatic nerve may be wrapped in scar tissue during revision surgery resulting in direct injury, or it may be overstretched due to stiffness of the tissue at the posterior border of the acetabulum. Intraoperative stimulation with an electric knife can also damage the sciatic nerve. Complex revision surgery can be performed by first revealing the sciatic nerve, which is usually found within the normal tissue distal to the scar and is released proximally. The risk of sciatic nerve injury occurring with limb extensions greater than 4 cm is high. If sciatic nerve palsy is found after surgery, the grouped femoral head should be short-necked early and the limb should be placed in the flexed hip and knee position after surgery to avoid the formation of permanent nerve injury.
How to determine the safe area for screw placement when installing acetabular screws?
The risk of injury to the internal and external pelvic vessels and nerves is associated with incorrect placement of transacetabular screws. A continuous line was made from the anterior superior iliac spine to the center of the acetabulum, and a plumb line was made through the center of the acetabulum to divide the acetabulum into four quadrants: anterior superior, anterior inferior, posterior superior, and posterior inferior. The anterior superior quadrant contains the external iliac artery and vein, and the anterior inferior quadrant contains the foramen ovale nerve and blood vessels. The posterior inferior quadrant has the sciatic nerve. The posterior superior quadrant is the safest and has strong bone, therefore the major and long screws should be fixed in the posterior superior quadrant.
How to avoid bilateral lower extremity inequality during hip arthroplasty?
Hip replacement inequality is very common and is of great concern to the patient. The risk of limb lengthening can be avoided by careful preoperative measurements and some intraoperative measurements. Preoperative template measurements to determine the center of rotation of the acetabulum, the type of prosthesis, neck length and offset, and comparison with the normal side of the joint can help avoid inequalities during surgery. There are several methods to determine the length of the limb during the operation: First, the “pull away test” can pull away the hip joint of the lower limb by 2-4 mm in the straight position. If the soft tissue is too lax, it is important to check whether the offset distance is too small in the process of increasing the neck length of the prosthesis, and by adjusting the offset distance, the tension of the hip joint can be maintained without excessively lengthening the limb. Second, choose a fixation point on each of the acetabulum and femur, and measure them before the osteotomy and during the fitting of the trial mold of the prosthesis respectively to determine whether the limb is lengthened. The relationship between the center of the femoral head and the apex of the greater trochanter should be measured. The center of the femoral head is usually slightly higher than the apex of the greater trochanter, but if the center of the acetabulum is displaced upward, the limb may still be shortened. The most reliable method is to use a combination of preoperative template measurements and intraoperative measurements, and it is important not to jeopardize the stability of the hip joint for the sake of equipoise.
What are the common causes of dislocation after hip arthroplasty? How to prevent and treat them.
Risk factors for dislocation after hip arthroplasty include revision surgery, posterior approach, inappropriate prosthesis position, use of a small femoral head, impingement (cement, bone, prosthesis), inadequate soft tissue tone, and failure of abductor function (weak abductor muscle or fracture of the greater trochanter). The rate of dislocation is slightly higher with the posterior approach. The incidence of dislocation can be significantly reduced by reconstruction of the posterior short external rotator muscle group and the joint capsule. Intraoperatively, the acetabular prosthesis should be prevented from tilting 45 degrees externally and 15 to 25 degrees anteriorly, and the femoral prosthesis should be placed at 5 to 10 degrees anteriorly; excessive anterior or posterior tilting may lead to dislocation. Bone cement and bony cavities protruding from the acetabular cup rim should be carefully removed to avoid impingement of the prosthesis with it. The use of a large diameter femoral head can increase the jump distance during dislocation (Jump distance) and reduce the risk of dislocation. Large femoral heads are currently available for metal-to-metal, ceramic-to-ceramic, and ultra-high cross-linked polyethylene matched articular surfaces. The tension of the gluteus medius muscle should be checked after prosthesis installation; inadequate gluteus medius tone can also lead to joint dislocation.
What are the common methods to prevent lower extremity venous embolism after hip arthroplasty?
Thromboembolism is the most common serious complication caused by total hip arthroplasty and is the most common cause of death within 3 months after surgery, accounting for more than 50% of deaths after total hip surgery. The incidence of venous thrombosis after total hip surgery can be 40-70%, with 2% experiencing serious complications, so it is important to prevent venous embolism after total hip replacement. Prevention methods include physical methods and pharmacological treatment. The risk of thrombosis from the choice of lumbar and epidural anesthesia is relatively small. Early activity reduces the incidence of thrombosis, and the patient is instructed to extend and flex the foot and lower leg as soon as the effects of anesthesia wear off after surgery. External continuous pneumatic compression boots and group venous plexus compression devices are less commonly used. I believe that the elastic stockings should not be wrapped too high to reach the knee and should always be applied bilaterally to the lower extremities. It is now generally accepted that every patient after hip arthroplasty should be given medication to prevent venous thrombosis. Commonly used drugs include: chemotherapy, low molecular heparin and aspirin. Low-molecular heparin is the most widely used, easy and safe to use, and can be injected subcutaneously once a day at a dose of 4000-6000 units. A new generation of oral venous thromboprophylaxis has been developed and is undergoing phase III clinical validation, making clinical application easier and more reliable. Aspirin is relatively safe, inexpensive and does not require monitoring of coagulation status, but its effects are controversial and it is basically ineffective when used alone, and the dosage can be 600 mg twice daily.
What steps in hip arthroplasty are prone to fracture? How can they be prevented?
Fractures of the femur and acetabulum can occur at all steps of total hip replacement. If the patient has little hip mobility (stiffness or tonicity) and significant osteoporosis, such as patients with ankylosing spondylitis, rheumatoid arthritis, elderly patients or patients with disuse osteoporosis, forceful abduction or rotation of the lower extremity during disinfection and dislocation can lead to femoral fracture. dislocation. If the patient has acetabular hyperplasia or femoral head entrapment, forced dislocation may lead to acetabular or femoral fracture. For patients who are difficult to dislocate manually, the femoral neck can be truncated by wire and the femoral head can be removed. Femoral fractures can occur when the marrow is expanded or a femoral prosthesis is inserted, mostly split fractures, which should be removed and the marrow cavity overturned and filed if the prosthesis is difficult to insert. A large non-cemented acetabular prosthesis inserted into a smaller acetabulum can result in an acetabular fracture; if the patient has a hard fracture, use the same type of prosthesis as the acetabular file or a +1 mm prosthesis. If the acetabulum is osteoporotic, the force of punching into the acetabular prosthesis will result in a fracture at the base of the socket, which should be replaced with a cemented prosthesis. If there is a perforation or weak area in the femur, a fracture may occur when the lower extremity is rotated during surgery, a plate can be tied to the perforation or weak area and removed after the surgery is completed. In conclusion, the incidence of fracture during total hip replacement is not low. Small fractures may affect the long-term fixation effect of the prosthesis, while serious fractures are difficult to deal with, so clinicians should pay great attention to this in order to avoid it as much as possible.
How is the mechanism of loosening of cemented and uncemented fixed femoral prostheses typified?
Gruen et al. have typed the mechanism of loosening of cemented femoral prostheses as follows.
Type I-piston-like activity, divided into two cases. Type Ia is sinking of the prosthetic stem in the bone cement, caused by incomplete cement wrapping or lack of internal upper support and poor fixation of the lateral middle, with displacement of the stem distally, producing a translucent band and fracture of the distal end of the bone cement; Type Ib is sinking of the stem and bone cement together in the medullary cavity, with a translucent band forming around the entire bone cement, in The translucent zone is often surrounded by reactive sclerotic bone.
Type II – medial stalk pivot role, caused by internal displacement of the proximal segment of the stalk and outward displacement of the distal end of the stalk due to inadequate cement support above and below the medial aspect, resulting in fracture of the cement in the middle and fracture of the sclerotic bone outside the tip of the prosthesis.
Type III – femoral spur pivot role, caused by inward or outward oscillation of the distal end of the shank, inadequate proximal support of the shank for fixation or the neck of the prosthesis overhanging the cortical bone of the femoral neck, lack of support of the distal end of the shank, shank and cement with the proximal end as the pivot point, distal end forming a kind of windshield rubbing-like activity, sclerotic hyperplasia of the cortical bone on the medial and lateral sides of the tip of the shank Type IV -The cantilever bending, caused by the lack of support at the proximal end of the shank while the distal end is firmly fixed, results in inward displacement and deformation of the proximal end of the shank, and at the proximal end, translucent areas appear on the medial and lateral sides of the shank, which can lead to shank fracture when further aggravated.
Engh and Bobyn classified the fixation of non-cemented femoral prostheses into three situations.
1, bone growing-in fixation.
2, stable fibrous fixation.
3, unstable fixation.
The above typing facilitates us both in analyzing the causes of prosthesis loosening and in determining the deficiencies of the procedure.
How to diagnose hip joint prosthesis loosening?
The diagnosis of loosening should be determined by a combination of X-ray manifestations and clinical symptoms. Generally speaking, the diagnosis of loosening can be established when there is a translucent band around the prosthesis greater than 2mm wide, or there is obvious displacement of the prosthesis, and the patient also has pain during weight bearing and activity, and the pain is relieved after rest.
CT scan is important to determine the extent of the bone defect and can be helpful in the diagnosis of loosening. An isotope bone scan is of some help, and if the bone around the prosthetic stalk remains nucleated and concentrated more than 6 months after surgery, it suggests a possible reactive process associated with loosening and possibly infection. Arthrography is of little value in establishing the diagnosis, and it is difficult to distinguish contrast from bone cement. Intra-articular injection of local anesthetic into the hip joint to reduce pain may determine that the patient’s symptoms are related to the hip joint, but does not determine that the symptoms are caused by loosening. The “twisting wrench” test performed during revision surgery is direct evidence of loosening of the prosthesis.
For loosening, it is important to identify whether the loosening is aseptic or infected. Some of the commonly used indications are shown in the table below.
Commonly used indicators to identify aseptic loosening and infected loosening Aseptic loosening Infected loosening occurs usually late postoperatively (more than 5 years) usually early postoperatively (less than 5 years) asymptomatic period with often no pain active pain, starting pain resting pain, nocturnal pain normal elevated ESR and CRP periosteal reaction no lace-like resorption, periosteal thickening translucent areas typical no or partial nuclear scan often no thickening thickening hip arthroplasty How are post-operative infections staged?
Infections after total hip replacement are often catastrophic, and although more than 90% of patients are now cured with good function and long duration of stay, the cost and pain of repeated surgeries can still be a disaster for patients, families and physicians.
The purpose of staging is to guide treatment and prognosis. The most commonly used staging is the one proposed by Tsukayama in 1996. This staging classifies post-operative hip arthroplasty infections into four types.
1. positive intraoperative culture, which refers to an undiagnosed infection before surgery and four culture specimens routinely taken intraoperatively; if two of them are positive and of the same bacteria, they are classified as this type, and treatment can be selected by applying sensitive antibiotics for 6 weeks.
2, early postoperative infection, which is an infection that occurs within 1 month after surgery, usually with clear signs of infection, such as redness, swelling, heat and pain as well as wound discharge, treatment can be chosen to try to preserve the prosthesis debridement.
3.Late postoperative chronic infection, refers to the infection occurring after 1 month postoperatively, usually with insidious onset, treatment may choose to revise.
4.Acute hematogenous infection refers to the infection of the hip prosthesis caused by bacteremia from other parts of the body. The joint functioned well before the onset of the disease, but the acute infection suddenly occurred.
How to diagnose infection after hip arthroplasty?
The diagnosis of artificial hip joint infection is difficult and should be determined based on a combination of clinical symptoms, laboratory tests, imaging, bacterial culture and pathological examination.
Pain is often the main clinical manifestation in most patients with joint infections. If a patient has persistent pain after surgery and pain at rest, the doctor must have a high suspicion that the patient has a joint infection. If fever, elevated blood sedimentation and CRP, and signs of loosening on x-ray are also present, antibiotics should be discontinued for 3 weeks for hip aspiration culture testing.
Sinus tracts are direct evidence of infection in artificial hips, but sinus tract formation is often of medical origin. In summary, the following four causes of sinus tract formation were found.
1, the high number and virulence of germs in the early stages of infection, leading to the formation of local abscesses breaking down.
2. delayed treatment of early infection and recurrent abscesses, which eventually form sinus tracts
3, infection followed by inappropriate debridement with non-healing incisions forming sinus tracts.
4. incomplete removal of the prosthesis and bone cement during revision surgery, formation of residuals, and failure to cure the infection, with subsequent formation of sinus tracts.
The latter three cases are all medical sinus tract formation and are all related to delayed or faulty diagnosis and treatment.
In patients with acute joint infections, temperature and white blood cell count tests are usually elevated; whereas in patients with chronic infections, temperature and blood tests are often normal and have little diagnostic significance. Blood sedimentation and C-reactive protein are more significant for diagnostic and therapeutic monitoring. If both sedimentation and C-reactive protein are elevated, infection should be highly suspected if other factors that cause both are excluded, such as rheumatoid, strong column, stress, etc.
Bacterial culture is the gold standard for determining infection, and if the culture is positive, the diagnosis can be established and treatment can be directed. However, because of the large amount of antibiotics often applied to patients during and after prosthetic arthroplasty and often after symptoms of infection, the rate of positive bacterial cultures is low and the rate of compliance between preoperative and intraoperative bacterial culture results is not very high. If the culture result is negative, the following means can be used to determine the diagnosis: joint fluid smear examination, tissue block culture, anaerobic bacteria culture and pathological examination. If the diagnosis is not confirmed by these means, the tissue may be taken for frozen section examination during debridement and the diagnosis may be confirmed if the average number of white blood cells per high magnification field exceeds 20.
What are the common treatments for post-arthroplasty infection?
The goal of treatment for post-arthroplasty infection is to eliminate the infection and restore the function of the affected limb. Antibiotic treatment and surgical debridement are the basic treatment methods. The main methods of treatment are: antibiotics for long-term infection control, prosthetic debridement, revision (stage I or II), arthroplasty, joint fusion and amputation. Antibiotic therapy is usually used in combination with surgery, but for some patients who are inoperable, such as elderly patients, frail patients or those who refuse surgery, antibiotics can be used for long-term infection control. Clearing the wound and being able to preserve the prosthesis is an attractive treatment for both physicians and patients. However, the success rate of treatment varies widely among reports, ranging from 0 to 100%.
There are several criteria for choosing to retain the prosthesis.
1. short duration of onset of symptoms (no more than 3 to 4 weeks).
2. gram-positive bacteria, sensitive to antibiotics.
3, absence of loosening of the prosthesis.
4, absence of sinus tracts.
5, no extensive local scarring.
Inappropriate retention of the prosthesis for debridement can make subsequent treatment more difficult. Revision is the most common and standard treatment method, including stage I revision and stage II revision. indications for stage I revision are usually: the patient is healthy, there are no sinus tracts, after the initial arthroplasty, the bacteria are sensitive to antibiotics, there are sensitive antibiotics that can be mixed into the bone cement, and it is possible to clear the wound thoroughly without bone grafting. stage II revision is the gold standard for treating post-arthroplasty hip, with a success rate of over 90%. It is suitable for most patients. Excisional arthroplasty and fusion are now rarely used in patients with infected hip replacements. In rare cases, amputation is required to control the infection in order to save life.