Overview of Total Knee Replacement Techniques

Having a total knee replacement surgery, or total knee arthroplasty (TKA), is a proven way to treat severe knee pain caused by a type of arthritis known as osteoarthritis. This surgery comes in handy especially when other less invasive treatments have not worked. Typically, osteoarthritis damages the knee’s cartilage- the cushioning layer on the ends of bones. If a patient has severe damage in multiple areas of their knee and cartilage cannot regenerate itself, a total knee replacement becomes an effective treatment option. TKA has shown to consistently reduce pain and improve one’s quality of life in the long term.

According to recent studies, total knee replacements are on the rise and it’s predicted that about 3.48 million surgeries will happen each year by 2030. Even though this surgery has become routine and quite common, it’s important for doctors to pay careful attention to the patient’s specific needs to reduce the risk of complications or the need for a future replacement. It’s worth noting that even with the most up-to-date techniques and technology, about 1 in 5 people might not be completely satisfied with their knee replacement surgery.

There are several types of total knee replacements, and the doctor will choose the one that’s best for a specific patient’s condition. Most patients receive one of three common types: a partial (or unicompartmental) knee replacement, a type that spares the knee’s stabilizing ligaments (cruciate retaining), or one that provides extra stability (posterior stabilizing). However, for those patients with severe knee deformity, such as extreme bowing, or in cases where a replacement knee has failed, doctors may consider a more specialized type of replacement. These include options like semi-constrained, hinged, or replacements that involve the lower end of the thigh bone (distal femoral).

Anatomy and Physiology of Total Knee Replacement Techniques

The knee is made up of three separate parts. These are called the medial tibiofemoral joint, the lateral tibiofemoral joint, and the patellofemoral joint.

The knee is often described like a door hinge as it mostly opens and closes, but it is a bit more complex. When the knee bends, it also turns in a subtle twisting motion and the thighbone slightly rolls back on the shinbone. There is also a unique rotary movement when the knee completely straightens out; this is known as the “screw home mechanism.” The outer side and inner side of the knee are different; the outer, or lateral, part of the joint is rounder and sits a bit higher while the inner, or medial, part of the knee joint is more concave, or curved inward. The inner femoral bone is larger than the outer one and carries more weight, which makes it denser and more prone to wear out, commonly seen in cases of osteoarthritis.

The knee has its stability thanks to several ligaments or elastic tissues that connect the bones:

  • Anterior Cruciate Ligament (ACL) – helps control the knee’s rotational movement and prevents the shinbone from slipping in front of the thighbone.
  • Posterior Cruciate Ligament (PCL) – keeps the shinbone from sliding backward under the thighbone and help for the thighbone to roll backward.
  • Lateral Collateral Ligament (LCL) – it helps protect against excessive outward bending or bowing and is often weakened when there is a significant outward deformation in the leg.
  • Medial Collateral Ligament (MCL) – prevents excessive inward bending or bowing and is generally weakened when there is a significant inward deformation in the leg.
  • Posterolateral Corner (PLC) – it’s the primary stabilizer for the outward rotation at the shinbone.

The lower thighbone angles outward about 9 degrees relative to the knee joint line, while the upper shinbone angles inward about 3 degrees relative to the knee joint line. This alignment helps the knee support the body’s weight.

The average angle between the thigh bone and kneecap, often called the Q angle, is between 13 and 19 degrees. If this angle increases, the kneecap is more likely to slide to the side and potentially dislocate.

Why do People Need Total Knee Replacement Techniques

The most frequent reason why people undergo a knee replacement surgery, also known as Total Knee Arthroplasty (TKA), is because of severe knee osteoarthritis. Knee osteoarthritis is a condition where the normal cushioning between joints — cartilage — wears away. This affects between 94 to 97% of knee replacements. The affected person would have tried other treatments like medication or physical therapy but their knee pain and function haven’t improved.

There are also other reasons that might make a knee replacement necessary. These include rheumatoid arthritis, which is a chronic inflammatory disorder, fractures around the joint, and malignant tumors. With malignant tumors, bigger knee prosthetics might be needed.

When a Person Should Avoid Total Knee Replacement Techniques

There are certain conditions that may prevent a person from having a knee replacement surgery, also known as Total Knee Arthroplasty (TKA). These factors may increase the risk of complications or hinder the successful outcome of the operation. A major concern would be an active infection in the affected knee or an ongoing bacterial infection elsewhere in the body.

Other concerns include major vascular diseases, which are conditions affecting the blood vessels. These could lead to difficulty in wound healing and a higher chance of getting an infection after the surgery.

Weight plays an important role too. Patients who are overweight or obese, especially those with a Body Mass Index (BMI) over 30, are at a higher risk of complications. Obesity not only increases the risk of infection but also may lead to other medical complications. This risk becomes even greater for patients with a BMI over 40.

Research shows that patients with a BMI over 40 could face higher chances of superficial and deep infections, a longer-surgery duration, deep vein thrombosis (which are blood clots deep within the body), prolonged hospital stay, kidney issues, wound opening after surgery, and the necessity for another operation. So, these factors need to be carefully discussed before planning a knee replacement surgery.

Equipment used for Total Knee Replacement Techniques

Each company that manufactures implants has a custom system equipped with the necessary tools and components needed for the surgery. Some common equipment that is used in every procedure and aids in carrying out the surgery efficiently and safely include:

  • A standard operation table
  • A place to hold the patient’s leg steady during surgery (De Mayo leg holder, paint roller or equivalent)
  • A tourniquet to restrict blood flow – its overall use is debated by medical experts and its usage depends on the surgeon’s preference
  • Devices to hold open incisions (retractors)
  • Tools to cut or reshape bone (osteotomes)
  • A specialized saw for bone cutting (sagittal saw)
  • A hammer-like tool (mallet)
  • Tools to spread open surgical sites (lamina spreaders)
  • Specific equipment for handling bone cement, including a cement mixer system and a pressure gun
  • A device for cleaning the surgical site with a pulsed flow of fluid (pulse lavage irrigation)
  • A device to remove fluid (suction)
  • A device for cutting tissues and stopping bleeding (Bovie electrocautery)

In more complicated operations, extra tools may be needed:

  • Scraping tools (curettes)
  • Drills for hollowing out bone (reamers)
  • Conical devices to reshape bone (cones)
  • Tubular sheaths for supporting bone tissue (sleeves)
  • Options for replacing bone, including grafted bone and fully adjustable stem devices

Going back to the 1950s, knee implants have continued to evolve. Dr. Insall and his team first outlined the various types of knee replacements in the 1970s. There are essentially two types: replacements that keep the knee ligaments intact, and those that remove them. They described four designs of varying complexity:

  1. Replacements for a single joint surface in the knee (Unicondylar)
  2. Replacements for two joint surfaces in the knee (Duocondylar)
  3. Geometric replacements, shaped to mimic the natural shape of the knee
  4. Guepar designs, which are more complex

Today’s knee implants have developed from these four original models and range from basic to very complex. They can be divided into the following categories: single compartment, cruciate retaining, posterior stabilizing, non-hinge constrained, and hinge-constrained prosthetic components.

The ‘Cruciate Retaining’ implant keeps one key ligament (the PCL) but removes the other (the ACL). This implant is suitable for those who have minor alignment issues but should not be used in patients with inflammatory arthritis due to the risk of ligament rupture. This type of implant offers several benefits such as fewer issues related to the kneecap, improved thigh muscle strength and the ability to climb stairs, and reduced stress on certain component parts of the implant. It also has certain disadvantages like post-surgical ligament degeneration or rupture that can lead to instability.

The ‘Posterior Stabilizing’ implant is used for patients with a missing PCL or inflammatory arthritis, or where the kneecap has previously been removed. This type of implant also offers a number of potential benefits such as relative ease of balancing ligaments in the knee and improved range of motion. However, it too has its disadvantages including wear and potential damage to certain parts, and some technical considerations.

There doesn’t seem to be a significant difference in how patients function after surgery, their satisfaction, or how long the implant lasts between these two types of implants.

The ‘Constrained Non-Hinged’ implant is used in cases where major ligaments are deficient, there’s moderate loss of bone, or laxity in the area that flexes and extends. It can offer stability but has disadvantages like bone loss and increased wear and tear.

The ‘Constrained Hinge’ implant is used in complex revision cases or cancer cases involving significant bone loss or ligament laxity. It operates with a rotating mechanism and offers advantages as a versatile option for complex cases but also has several disadvantages, including the requirement for significant bone resection and risk of loosening over time due to the constraint.

Who is needed to perform Total Knee Replacement Techniques?

Knee replacement surgery, also known as total joint arthroplasty, has changed the way it is paid for. Instead of charging for each service provided (fee-for-service), it’s now covered by a bundled payment. This system seeks to encourage quality care over doing higher volumes of surgeries. This change came into effect in 2015 when Medicare and Medicaid Services introduced a new way of organizing care for knee replacements called the Comprehensive Care for Joint Replacement Model or CJR.

Research undertaken in 2014 showed that 70% of the cost of a knee replacement was incurred after the surgery. The CJR is designed to help lower these costs and reduce any complications. Because of this new approach, hospitals have developed standard procedures, and a team of health professionals are now involved in each knee replacement surgery to ensure the best outcome for the patient.

This team can include the following individuals: Your regular doctor (primary care physician) and a joint class instructor might provide initial guidance and education. Nurses who specialize in care before, during, and after surgery (preoperative, intraoperative, and post-anesthesia nurses) assist at various stages. In the operating room, there might also be scrub technician and a circulating RN, who help ensure tools are sterile and the surgery goes smoothly.

Additional support may be provided by a physician assistant or a specialist medical professional in training (resident physician), as well as an orthopedic surgeon who performs the surgery. After the procedure, a case manager coordinates care and treatment while physical and occupational therapists assist with recovery. Home care may be provided by a home health care nurse and outpatient physical therapy may be necessary.

Preparing for Total Knee Replacement Techniques

Before surgery to replace the knee, known as knee arthroplasty, a number of non-surgical treatments are used to try and improve your condition. There are options involving medications as well as treatments that don’t use drugs. These treatments have been researched extensively and the American Academy of Orthopaedic Surgeons (AAOS) has provided guidelines, based on the best available evidence, on how best to use them.

The AAOS advises low-impact aerobic exercises (activities that gently increase your heart rate), training to improve your muscles and nerves, and strength-building. They also suggest the use of non-steroidal anti-inflammatory drugs (NSAIDS) and a medication called tramadol to help with pain.

For those with a body mass index (BMI) over 25, they recommend losing weight. However, methods such as acupuncture and certain supplements (glucosamine/chondroitin) and procedures (viscosupplementation) are advised against. They also mildly discourage the use of special shoe inserts (lateral wedge insoles).

As for certain forms of physical therapy such as chiropractic, specific electrical treatments, steroid injections, and several types of medication, the AAOS does not make a firm recommendation one way or the other.

Before your knee replacement surgery, a thorough evaluation will be carried out. This can vary widely between different medical professionals and hospitals, but typically includes a detailed look into your medical history and a physical examination. If you have risks associated with a number of chronic diseases, or if you smoke or drink alcohol, these factors would be carefully evaluated.

Your primary care provider will usually assess if you are fit enough for surgery, particularly if you have complications with your heart. You might also have to see specialists depending on your other health conditions. This pre-surgery assessment can help identify any potential risk factors, potentially reducing the cost of your hospital stay and even making your stay shorter.

Planning for the surgery itself involves examining previous surgical scars, measuring your limbs, checking for any abnormal shape, assessing your bodily movement, stability, and walking patterns. Also, the blood flow in your leg will be evaluated. You may be referred to a vascular specialist, especially if you have existing issues with your blood vessels.

Images (X-rays) of your legs under your body weight will be taken to check the shape and structure of your knee. Computer software may be used to lay plans for the surgery accurately, and if required, customized implants could be made using various scanning techniques.

Additional lab tests will be done before surgery. These may include tests to measure your blood cells, to monitor sugar control in patients with diabetes, to check your overall nutritional status (which can impact wound healing), and to screen for harmful bacteria. These preparations help doctors to ensure the best possible outcome from your knee replacement surgery.

How is Total Knee Replacement Techniques performed

In a knee replacement procedure, you will lay flat on a surgical bed and you will be given anesthesia for pain relief- this might be either general anesthesia, which puts you to sleep, or spinal anesthesia, which numbs you below the waist. The choice between the two doesn’t have a significant effect on the risk of surgical complications according to various studies.

The surgeon will make an incision down the center of your knee. After doing so, they will carefully protect the blood flow and nearby tissue, ensuring the area around your knee can be properly closed at the end of the surgery. The surgeon will then handle the tissue at the top part of your shinbone. The same is done on the other side of the knee. However, the work will be a bit more intense if your knee bows inward.

Removing the fat pad located under the knee is optional. Things like the knee’s shock absorbers and the knee ligaments may need to be removed, depending on the type of implant used. If your kneecap is severely affected by arthritis or causes significant pain, it may be resurfaced.

The exact steps the surgeon takes will depend on the surgical technique used. One approach is called Measured Resection, where the surgeon will remove the exact amount of bone to achieve a neutral positioning of the knee. They will use an internal guide in the thigh bone and an external guide in the shin bone. They will also make sure the top part of the shinbone is leveled properly. The surgeon makes specific jots to help them place the implant in a neutral rotation. Their goal is to balance the ligaments around the knee in both a straight and bent position.

Another approach is Gap Balancing, the same goal of a balanced knee is kept, but the difference lies in the technique. Here the surgeon will adjust the ligaments around your knee to achieve a balanced position in extension and flexion (straight and bent) before shaping the bones.

Whatever the approach, avoiding a kneecap that doesn’t move smoothly is crucial. The surgeon will take steps to prevent this by correctly positioning the implants and choosing the right size for your kneecap.

At the end of the procedure, the surgeon will carefully close the surgical cut. Various types of stitches can be used depending on individual factors. A special dressing will then be applied to the wound to protect it and help it heal. In some cases, the surgeon might use a device called a wound VAC that applies negative pressure to the wound, promoting healing and decreasing the risk of infection.

Possible Complications of Total Knee Replacement Techniques

Periprosthetic fractures are breaks in the bone that happen around a joint prosthesis, which is pretty much an artificial joint. They can happen in the lower part of your thigh bone, the upper part of your shin bone, or your kneecap. These fractures usually occur above the rounded part of your thigh bone. When doctors classify these fractures, they generally use the Lewis and Rorabeck system. This system breaks down the fractures into three types based on severity and stability of the artificial joint. However, it doesn’t account for fractures that occur during surgery. Risk factors that may increase the likelihood of fractures include:

* Notching (indents) in the thigh bone
* Weakening bone conditions like osteoporosis or osteolysis
* Loosening of the artificial joint
* Rheumatoid arthritis
* Neurologic disorders

Additionally, using corticosteroids, being a woman, and aging may also contribute to risk. Treatments could range from surgery to reset the bone, keeping your knee still in a brace, redoing the joint replacement if the components are loose, or even getting a new thigh bone end if there’s not enough bone left or too many pieces to put back together.

Prosthetic joint infections happen in 1 to 2% of people who get knee replacements. The most common bacteria that cause these are Staphylococcus aureus and Staphylococcus epidermidis. Infections can happen either within the first 6 weeks after surgery (acute) or after 6 weeks (chronic). Diagnosis usually involves blood tests and analyzing joint fluid to check for signs of infection. If other tests can’t confirm anything, doctors might use a bone scan to look for any unusual changes.

Treatment usually involves IV antibiotics for 12 weeks. For acute infections, doctors might swap out the plastic part of your artificial joint and clean the area while removing any damaged tissue. However, this only works about 50 to 55% of the time. If it’s a chronic infection, or if earlier treatments didn’t work, doctors might use a two-stage process: this involves putting in an antibiotic-loaded spacer for about 2 to 3 months to clear the infection before putting in a new joint.

Other complications that might occur after knee replacements include loosening of the artificial joint, abnormal movement of the kneecap, damage to the knee’s extensor mechanism, instability, stiffness, patellar clunk (a clicking noise or sensation from the kneecap), blood vessel injury, damage to the peroneal nerve, wound complications, allergic reactions to the joint’s metal, and excessive bone formation.

What Else Should I Know About Total Knee Replacement Techniques?

Understanding the principles of joint replacement surgery, or arthroplasty, and improving the consistency and quality of care is very crucial. It’s estimated that by 2030, approximately 3.48 million total knee replacement surgeries (also referred to as total knee arthroplasty or TKA) will be performed every year. Today, 20% of patients who undergo a TKA are not completely satisfied due to various reasons. This dissatisfaction puts a high amount of stress and cost on our healthcare system.

Most importantly, healthcare professionals should take utmost care and diligence before performing a TKA on any patient. This is because if the outcome is not positive, it can lead to a series of other negative effects afterward. In addition, as our healthcare systems continue to evolve and adopt new payment models and efficient practices, everyone involved in healthcare – from doctors and nurses to hospitals and healthcare facilities – face increasing pressure. They are expected to provide high-quality healthcare that offers good value for the cost, at all levels and more efficiently than ever.

Frequently asked questions

1. What type of total knee replacement technique do you recommend for my specific condition? 2. What are the potential benefits and risks associated with the chosen technique? 3. How long is the recovery period for this technique? 4. Are there any alternative techniques or treatments that I should consider? 5. How many total knee replacement surgeries have you performed using this technique?

Total Knee Replacement Techniques can have a positive impact on individuals who are experiencing knee problems. By replacing the damaged knee joint with an artificial one, these techniques can help improve mobility, reduce pain, and enhance overall quality of life. However, it is important to consult with a healthcare professional to determine if this procedure is suitable for your specific condition.

You may need Total Knee Replacement Techniques if you have certain conditions or factors that prevent you from having a knee replacement surgery. These factors include active infection in the affected knee or elsewhere in the body, major vascular diseases, and being overweight or obese. These conditions can increase the risk of complications and hinder the successful outcome of the surgery. It is important to carefully discuss these factors with your doctor before planning a knee replacement surgery.

A person should not get Total Knee Replacement Techniques if they have an active infection in the affected knee or elsewhere in the body, major vascular diseases, or if they are overweight or obese, especially with a BMI over 30. These conditions increase the risk of complications and hinder the successful outcome of the surgery.

The text does not provide specific information about the recovery time for Total Knee Replacement Techniques.

To prepare for Total Knee Replacement Techniques, the patient should first try non-surgical treatments such as low-impact aerobic exercises, strength-building exercises, and medications like non-steroidal anti-inflammatory drugs (NSAIDs) and tramadol to manage pain. They should also consider losing weight if they have a BMI over 25. Before the surgery, a thorough evaluation will be done, including a medical history review, physical examination, and lab tests. The patient may also need to see specialists and undergo imaging tests to assess the knee's structure and shape.

The complications of Total Knee Replacement Techniques include periprosthetic fractures, prosthetic joint infections, loosening of the artificial joint, abnormal movement of the kneecap, damage to the knee's extensor mechanism, instability, stiffness, patellar clunk, blood vessel injury, damage to the peroneal nerve, wound complications, allergic reactions to the joint's metal, and excessive bone formation.

Severe knee pain and decreased knee function that have not improved with other treatments like medication or physical therapy are symptoms that would require Total Knee Replacement Techniques. Other reasons that might make a knee replacement necessary include rheumatoid arthritis, fractures around the joint, and malignant tumors.

There is no mention of pregnancy in the provided text, so it is unclear whether total knee replacement techniques are safe in pregnancy. It is recommended to consult with a healthcare professional for personalized advice regarding knee replacement surgery during pregnancy.

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