Minimally Invasive Vs Total Knee Replacement
Total knee replacement is a surgical procedure to replace the ends of the bone forming the knee joint with artificial parts. While the traditional approach to knee replacement surgery has been around for many years, minimally invasive techniques for knee replacement have been introduced recently.
Minimally invasive techniques offer some advantages over the traditional technique but not all patients may be candidates for minimally invasive knee replacement. Besides, over the long term, the outcomes for both the traditional and the minimally invasive techniques have been shown to be similar.
During a traditional knee replacement surgery, the surgeon gives an incision in front of the knee joint. After dissecting the tissues, the surgeon cuts the quadriceps tendon along the side of the kneecap. A tissue along the side of the patellar tendon (an extension of the quadriceps tendon) is also cut.
The quadriceps tendon attached to the four quadriceps muscles present in front of the thigh. The four quadriceps muscles help in the extension of the leg at the knee joint. The integrity of the muscles, quadriceps tendon, patella, knee joint, and patellar tendon is required for straightening the leg.
The kneecap is then usually everted to get a better exposure of the joint. The surgeon then proceeds to surgically cut the bone ends of the thigh bone and the shin bone. The cuts are made to contour the shape so the prosthetic implants fit over the cut ends.
While the bony preparation of the cut ends is an important aspect of the replacement surgery, the most crucial part in stabilizing the knee joint. Stabilizing the artificial joint requires balancing the forces acting around the knee joint. The diseased knee joint is often deformed (knock knees or bow legs). The deformity is also corrected during the surgery.
After the knee is balanced, metal prosthetic parts are fixed using bone cement on the thigh bone and the shin bone. A high-grade plastic is inserted in between the metal parts to smoothen the motion. The incision is closed in layered and the patient is usually able to walk the evening of the surgery or the next day.
Minimally invasive knee replacement technique involves a smaller incision and less cutting of the tissue. The surgeon gives a smaller incision and instead of cutting the quadriceps tendon, the surgeon lifts the vastus medialis muscle. In some techniques, the vastus medialis may be cut instead of the quadriceps tendon.
The surgeon then accesses the knee joint similarly but may not dislocate the tibia to perform the bone cuts. Implants similar to a traditional knee replacement are fixed using bone cement. The incision is then closed in layers. Some advantages of a minimally invasive technique are:
- A small skin incision leads to a smaller scar on the knee which may be aesthetically important for some patients.
- A small incision and less cutting of the tissues leads to less intraoperative blood loss as compared to the traditional approach.
- Patients treated with minimally invasive techniques are able to start the rehabilitation process earlier and may have to stay at the hospital for fewer days as compared to traditional. Although, recent studies have suggested similar postoperative stays for both traditional and minimally invasive.
- As less tissue is cut during a minimally invasive technique, the patients may be expected to experience less postoperative pain.
However, there may be potential disadvantages to a minimally invasive knee replacement surgery.
- The surgeon works with a very small field of surgery using a minimally invasive technique. The small field of surgery may potentially interfere with the correct placement of the implants.
- The narrow field of surgery may also lead to potential stretching of the tissues while using the retractors. The stretching may also lead to rupture of the patellar tendon.
- The minimally invasive technique may not be used in all patients. The technique is generally not indicated in patients who are obese, muscular, or with severe deformities such as bow legs or knock knees.
- The technique also has a difficult learning curve for the surgeon as compared to the traditional approach.
Recent studies have indicated identical outcomes in both the traditional approach and the minimally invasive approach. As discussed earlier, a knee replacement surgery is much more than simply replacing the ends of the bone. The long-term survival of the implants depends a great deal upon the intraoperative balancing of the knee and the stability of the joint in motion.
Knee replacement surgeries have revolutionized the management of knee pain due to arthritis. A vast number of patients benefit from knee replacement surgeries annually. The traditional approach has been in use for many years and has excellent results.
While the minimally invasive approach has a number of potential benefits, the technique may not be suitable for all patients and requires greater surgical expertise. Speak with your orthopedic surgeon, what type of knee replacement technique may be best suited in your case.