Knee

Knee Replacement Orthopedic Surgery Overview

Knee Replacement Orthopedic Surgery Overview.

Total knee replacement is one of the most successful surgical procedures. The first knee replacement was performed more than 35 years ago. Today, more than 400,000 procedures are being performed every year in the United States alone. It is a fairly routine procedure. Total knee replacement, also called Total Knee Arthroplasty, involves removing the diseased bone and cartilage and resurfacing it with orthopedic implants.

The word “replacement” gives the impression that your surgeon is removing the entire knee. However, your surgeon will only resurface the damaged bone and cartilage of your joint. During surgery, the joint is exposed by an incision, made down the center or off to the side of the knee. The damaged bone ends are then resurfaced with components designed to re-create the natural contours of the bones in a healthy knee. The metal and polyethylene (plastic) implants allow the bones to smoothly glide against each other, like your natural cartilage.

Total knee replacement is performed while you are under anesthesia. There are various types of anesthesia available and your surgeon will explain the options before your surgery.

The length of surgery may vary from approximately one to two hours. Care before surgery and time spent in the recovery room can add an additional one or two hours to the procedure.

The Gender Issue

Differences in Size and Shape

Design teams take into account the obvious anatomical differences between narrow, smaller—typically female—knees and wider, larger knee dimensions typically seen in men. This is a fact that some other knee system designs are just now addressing.

Some knee implant designs are based simply on an average size of women’s and men’s knees combined. One manufacturer found that the shape of its implant did not successfully meet the needs of many women so they created a new gender-specific implant for women to address this design deficiency. This new “female knee” has yet to demonstrate long-term clinical effectiveness and, based on review of anatomic data, may fail to meet the needs of a majority of female patients.

Some manufactures feature a wide range of specific shapes and sizes to meet the anatomic needs of individual patients, whether male or female. Plus, unlike newer knee systems, the correct choice offers the confidence you can only get from excellent, longstanding clinical results.

Differences in Patellar Tracking

When bending (flexing) a knee, the kneecap naturally “floats”, moving slightly to both the inside and the outside of the knee. Studies have shown that the average person’s kneecap moves slightly to the inside as the knee is extended.

Because women tend to have wider hips, their muscles and ligaments may cause their kneecaps to track at a slightly different angle than men’s. One manufacturer has attempted to address this difference by designing a “female” implant that directs the kneecap to track to the outside at a specific angle, regardless of the individual patient’s unique anatomy, soft tissue or muscle structure. Unnatural patellar tracking can put stress on muscles and ligaments and cause post-operative pain.

By contrast, the specially designed knee replacements, with a wide femoral groove, allows the patient’s kneecap to track naturally (to either the inside or the outside) during normal bending and straightening of the leg.

Preserving Your Bone While Providing For Flexibility

The surgical procedure of knee replacement requires that a small amount of bone be removed to place the implant in position. Several implants and surgical instrumentation are all designed with bone preservation in mind.

To achieve the highest degrees of flexion, some of the new “female” implants require that more of your own, healthy bone be removed to accommodate a thicker, bulkier implant. Streamlined design can achieve high flexion while preserving as much of your natural bone as possible.

The Right Choice for You

Your surgeon will consider a wide variety of variables when selecting the knee implant that’s right for you. Your age, height, weight, lifestyle and your general health are among the most important factors. There are total knee system that are designed to accommodate these and other variations in anatomy to provide you the best possible outcome.