Total knee replacement is a common procedure undertaken to correct damaged or worn surfaces of the knee. Replacing the worn surface with an implant reduces pain and increases mobility, allowing you to return to your normal, active lifestyle.
The traditional approach to knee replacement involves making a long, vertical incision in the center of the knee to enable the surgeon to view and access the joint. Minimally invasive total knee replacement is a variation of this approach. In this procedure the surgeon uses a shorter incision and a less-invasive technique to expose the joint with the goal of speeding the patient’s recovery. Unlike traditional total knee replacement, the minimally invasive technique is not suitable for all patients.
Traditional Knee Replacement
In a traditional knee replacement procedure, an 8- to 10-inch vertical incision is made over the front of the knee to expose the joint. The surgeon will then:
- Prepare the bone. The damaged cartilage surfaces at the ends of the femur and tibia are removed along with a small amount of underlying bone.
- Position the metal implants. The removed cartilage and bone is replaced with metal components that recreate the surface of the joint.
- Resurface the patella. The undersurface of the kneecap is cut and resurfaced with a plastic button. (In certain cases, the surgeon will elect not to resurface the patella.)
- Insert a spacer. A plastic spacer is inserted between the metal components to create a smooth gliding surface.
Minimally Invasive Knee Replacement
A minimally invasive knee replacement involves less cutting of the tissue surrounding the knee. The artificial implants used in these procedures are identical to those used in traditional knee replacements, though specially designed surgical instruments are used to prepare the femur and tibia and to place the implants properly.
Minimally invasive knee replacement is performed using a shorter incision: 4 to 6 inches versus 8 to 10 inches for traditional knee replacement. The smaller incision allows for less tissue disturbance. In this procedure the technique used to open the knee is less invasive.
The techniques used in minimally invasive knee replacement are generally considered to be “quadriceps sparing,” meaning they avoid trauma to the quadriceps tendon and muscles in the front of the thigh. Other minimally invasive techniques called “midvastus” and “subvastus” make small incisions in the muscle but are also less invasive than traditional knee replacement. Because the techniques used to expose the joint involve less disruption to the muscle, they often lead to less post-operative pain and a faster recovery time.
Physical rehabilitation is a critical component of recovery. Your surgeon will provide you with specific exercises to help increase your range of motion and restore your strength.
In general, candidates for minimal incision procedures are thinner, younger, healthier and motivated to participate in the rehabilitation process. Minimally invasive surgeries may be less suitable for patients who are overweight or who have undergone previous knee surgeries.
In addition, patients who have a significant deformity of the knee, those who are very muscular, and those with health problems that may slow wound healing may be at a higher risk for problems from minimally invasive total knee replacement.