Knee replacement surgery is one of the most common orthopaedic procedures performed in the United States. The American Academy of Orthopaedic Surgeons states that approximately 581,000 knee replacement surgeries are performed annually in the United States. The two primary types of knee replacement surgery differ in terms of the extent of joint replacement. Additionally, different surgical approaches have been developed that may be utilized with either procedure.
Total Knee Replacement
Total knee replacement is indicated for people with severe arthritis or other damage involving the majority of the joint surfaces. This surgery involves replacement of the lower end of the thighbone, the upper end of the shinbone and the inner surface of the kneecap. Metal prostheses replace the bone ends. A hard plastic component is sandwiched between the metal surfaces, replacing the natural cartilage cushion. A plastic disk is usually affixed to the inner surface of the kneecap to facilitate smooth movement over the replacement joint.
The University of Washington Department of Orthopaedics and Sports Medicine reports that the average hospital stay for total knee replacement is approximately three days, followed by roughly five days of inpatient rehabilitation. Patients who require a less strenuous rehabilitation program may stay at an extended-care facility to recover sufficiently for discharge home. Walking assistance devices such as a walker, crutches or a cane are typically needed for several weeks to month after surgery.
Partial Knee Replacement
The lower end of the thighbone consists of two bony knobs that interface with cartilage cushions--the medial and lateral meniscus--resting on top of the shinbone. Although most knee damage involves both the medial and lateral regions, or compartments, some people have joint deterioration limited to one compartment. For these patients, a partial knee replacement, also known as a unicompartmental knee replacement, may be an option. The American Academy of Orthopaedic Surgeons notes that approximately seven out of 100 people considering joint replacement because of severe knee arthritis are candidates for partial replacement surgery.
The prosthetic parts for a partial knee replacement are similar to those used in a total knee replacement, but modified for use in one compartment. Hospitalization and recovery time with a unicompartmental procedure are shorter than with a total knee replacement. Rehabilitation remains an important aspect of the recovery process.
Minimally Invasive Knee Replacement
Minimally invasive knee replacement involves use of a smaller incision to perform either a total or partial joint procedure. The American Academy of Orthopaedic Surgeons reports that the average incision for a traditional total knee replacement is approximately eight to 10 inches, compared to four to six inches with a minimally invasive approach.
The American Association of Hip and Knee Surgeons urges careful consideration in choosing a traditional versus a less invasive surgical approach. The Association notes that minimally invasive knee replacement procedures may be more challenging than the traditional approach in highly muscular or obese patients and in people with severe joint deformity.
References
- American Academy of Orthopaedic Surgeons: Total Knee Replacement
- UW Medicine, Department of Orthopaedics and Sports Medicine: Total Knee Replacement, A Patient's Guide
- American Academy of Orthopaedic Surgeons: Unicompartmental Knee Replacement
- American Academy of Orthopaedic Surgeons: Minimally Invasive Total Knee Replacement
- UW Medicine, Department of Orthopaedics and Sports Medicine: A Patient's Guide to Partial Knee Replacement using Minimally-Invasive Surgery (MIS) Techniques
