COMPLEX AND REVISION KNEE REPLACEMENT

Replacement

Complex and Revision Knee Replacement

Total knee replacement stands as one of the most successful medical procedures known. In the majority of instances, it grants individuals a life devoid of persistent knee pain, facilitating a more fulfilling and active lifestyle. In this procedure, termed primary total knee replacement, the original knee joint is substituted with a prosthetic made of metal and plastic elements. While the success rate of total knee replacements is high, there may arise issues such as implant wear and loosening over time, necessitating a revision surgery to replace the initial components.

Revision surgeries encompass various approaches. Sometimes, only one component of the implant requires modification, while in other cases, all three components—the femoral, tibial, and patellar—mandate removal or replacement, alongside rebuilding the surrounding bone with augmentations (metal pieces that serve as substitutes for absent bone) or bone grafts. Damages to the bone might complicate the utilization of standard total knee implants for revision knee replacement. Typically, specialized implants featuring longer and thicker stems, providing deeper insertion into the bone for enhanced support, are utilized in such scenarios by the surgeon.

Implant Loosening and Wear

Osteolysis has resulted in the loosening of the tibial component from the bone in the context of total knee replacement. The success of such a replacement hinges on the firm attachment of the implant to the bone. Initially, during surgery, the implant is securely fixed either by cementing it in place or by relying on bone ingrowth into its surface. However, over time, the implant may lose its grip on the bone, resulting in discomfort in the knee. The exact cause of this loosening is often uncertain, but it can be exacerbated by high-impact activities, excessive body weight, and wear and tear of the plastic spacer between the metal components of the implant. Furthermore, younger patients who undergo knee replacement surgery may outlast the expected lifespan of their artificial knee, increasing the likelihood of needing revision surgery due to loosening or deterioration. In some instances, minuscule particles from the worn plastic spacer can gather around the joint and trigger an immune response in the body. This immune reaction not only targets these particles but also attacks the healthy bone surrounding the implant, leading to osteolysis. This condition entails the deterioration of bone around the implant, resulting in its instability or looseness.

Infection

Infection poses a potential risk in any surgical procedure, including total knee replacement, whether during your hospital stay or after returning home, and sometimes even years later. If an artificial joint becomes infected, it can result in stiffness, pain, and the implant may start to detach from the bone. Even if the implant remains firmly attached, the presence of infection can lead to pain, swelling, and drainage, potentially necessitating further surgery.

During the initial stages of treatment for joint replacement infection, an antibiotic spacer may be placed in the knee.

Revision surgery for infection can be approached in two ways, depending on factors such as the type of bacteria, the duration and severity of the infection, as well as patient preferences.

Debridement: In certain cases, the infection can be cleared by washing out the bacteria, exchanging the plastic spacer, and retaining the metal implants.

Staged surgery: In other instances, complete removal of the implant may be necessary. If this is the case, the revision is typically conducted in two separate surgeries. Initially, the implant is removed, and a temporary cement spacer containing antibiotics is placed in the knee. This spacer helps combat the infection and remains in the knee for several weeks, during which intravenous antibiotics are administered. Once the infection is eradicated, a second surgery is performed to remove the antibiotic spacer and insert a new prosthesis. While removing the implant offers a higher likelihood of curing the infection, it also entails a longer recovery period.

Instability

If the ligaments surrounding your knee suffer damage or are not properly balanced, it can lead to instability in your knee. Since most implants are crafted to function alongside the patient's natural ligaments, any alterations in these ligaments might hinder the proper functioning of the implant. You may notice recurring swelling and a feeling that your knee is unstable or "giving way." If non-surgical methods like bracing and physical therapy fail to address knee instability, revision surgery may be necessary.

Stiffness

Occasionally, a total knee replacement might not provide the necessary range of motion for everyday tasks due to excessive scar tissue formation around the knee joint. If this occurs, your physician may recommend a procedure known as "manipulation under anesthesia." During this procedure, you'll receive anesthesia to alleviate pain, allowing the doctor to forcefully flex your knee to break down scar tissue. Typically, this approach successfully enhances range of motion, but in some cases, stiffness may persist. If extensive scar tissue or component positioning continues to restrict movement, revision surgery may be necessary.

Fracture

A periprosthetic fracture refers to a bone break happening in the vicinity of components used in a total knee replacement. Typically caused by a fall, these fractures commonly necessitate further surgical intervention. Your doctor will evaluate various factors to determine the necessary extent of revision. These factors include the condition of the remaining bone, the specific type and location of the fracture, and whether the implant has become loose. In cases where the bone is extensively fractured or weakened due to osteoporosis, the damaged section may require complete replacement with a larger revision component.

Complex Knee Replacement

Complex knee replacement refers to cases where patients present with a painful arthritic knee accompanied by additional complications in or around the knee joint. These complications may include old fractures of the lower femur or upper tibia that have healed in a misaligned manner, prior surgeries involving internal fixation devices such as plates and screws, pronounced deformities due to significant bone loss, or instability caused by ligament stretching or tearing. In such instances, a standard primary knee replacement may prove insufficient, necessitating a larger and more intricate procedure known as a complex primary knee replacement.

This advanced procedure often requires a range of supplementary techniques, such as the use of specialized implants with longer stems, metallic augments to replace lost bone, bone grafting, and larger plastic liners. These measures are employed to restore proper limb length and alignment, replace missing bone, and ensure the adequate tensioning of ligaments and surrounding soft tissues. In cases where deformities are severe or previous trauma has compromised ligament integrity, temporary balancing with a tightly fitting plastic liner may be appropriate.

When substantial bone loss is present, typically due to trauma or previous surgeries, a larger "endoprosthesis" may be necessary to replace significant bone segments. These implants allow for the reattachment of soft tissues like ligaments and tendons, requiring meticulous preoperative planning and intraoperative attention to detail to ensure proper limb alignment and functioning.

In scenarios where both bony and soft tissue deficits exist and stability cannot be achieved through standard means, a "rotating hinge" type knee replacement may be considered. These implants feature a mechanical hinge that flexes, extends, and rotates, albeit requiring a more extensive surgical approach and longer recovery times.

In cases necessitating these complex procedures, achieving optimal function and range of motion may be challenging, with a shift in surgical goals towards pain management, improved mobility, and equalization of limb length. While careful patient selection and preoperative planning aim to identify those likely to require such procedures, unexpected findings during surgery may prompt a deviation from standard implants to more specialized options.

Despite the complexity involved, satisfactory outcomes in terms of alignment, motion, and pain relief are typically achievable with these advanced knee replacement techniques.