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Total knee arthroplasty and total hip arthroplasty are commonly performed surgeries for damaged arthritic joints. This type of surgery is highly successful. Recovery can be difficult and requires extensive physical therapy.
Types of conditions treated with Joint Replacement Surgery:
| Figure 1 Below shows the X-Ray of a normal Hip & and Arthritic Hip. Click on each image to see a larger version. | |
 Normal Hip X-Ray |
 Arthritic Hip X-Ray |
| Figure 2 Below shows the X-Ray of a normal Knee & and Arthritic Knee. Click on each image to see a larger version. | |
 Normal Knee X-Ray |
 Arthritic Knee X-Ray |
Minimally invasive surgery of the knee and hip is a type of operation that is accomplished through smaller incisions. This is a joint replacement surgery in which the typical incision lengths are four inches for shorter people and five inches for tall people.
 Fig 3: Model of Knee replacement surgery Standard Incision = Green Line; MIS Incision = Black line |
This approach avoids cutting of tendons and ligaments. The tools are downsized and reshaped to work through smaller incisions. The exposure of the tissues is decreased. There is less pain, and there is an improvement in the early rehabilitation parameters. Less tissue exposed allows for an easier healing process. At the knee, a quadriceps sparing approach is performed in which the patella is tilted and shifted, but not everted (there is less tension on the quadriceps). This allows for an easier recovery.
There are certain conditions were this procedure might have limitations.
This may not be the proper approach for people with large deformities or malalignment of the leg due to long-standing arthritic destruction.
This type of surgery is performed under a nerve block and/or general anesthesia. At the knee, a quadriceps sparing approach is performed. Specifically, this is an incision where the muscle of the quadriceps is lifted, and the patella is tilted. During standard knee replacement surgery, the patella is turned and everted, causing excessive tension on the quadriceps. This everting maneuver of the patella is avoided during MIS surgery.
Frequent shifting of the retractors increases the field of vision for the surgeon, and this maneuvering creates a “mobile window”. The total knee arthroplasty components consist of a bearing surface of chrome cobalt metal alloy and high-density polyethylene (highly crosslinked – high molecular weight polymer) that resists wear. Component surfaces that are in touch with the native bone are made of titanium or tantalum.
| Figure 4 Below Shows Knee Replacement Components. Click on each image to see a larger version. | |
 Posterior View |
 Anterior View |
These metals can be textured to allow bone ingrowth. This is a process of healing that is called porous ingrowth. Cement (methylmethacrylate) is used when there is concern of bone density loss, and there is need for additional support to create a secure structure. Jigs and alignment devices are used to ensure the proper bone cuts are made with a battery operated saw. The components are shaped and sized to simulate or reproduce the original knee or hip structure. In doing this, there is a simulation of the normal knee or hip anatomy.
At the hip a posterior four-inch incision is used that is at the level of the greater trochanter. The joint is entered by splitting the gluteal and piriformis musculature. Retractors are used for preparation of the acetabulum. We use retractors with fiberoptic lighting. Curved and angled instruments are used for preparation of the socket (acetabulum).
Total hip arthroplasty components: We commonly use metal on metal (forged chrome-cobalt alloy) components.
 Fig 5: Hip Replacement COmponents |
This allows for the use of a larger head and helps reproduce the normal anatomy of the hip. With this, there is a decreased chance of dislocation. The standard bearing is that of a chrome cobalt and polyethylene structure. Ceramic surfaces can be placed in selected circumstances. The femoral component consists of a ball or head and a stem that fits inside the top part of the femur bone. The surgical time is approximately two hours.
Antibiotics are used for 24 hours after a surgery. Analgesics consist of intravenous and oral medication. Physical therapy starts the afternoon of the day of surgery or the following morning. Typical hospitalization is two days. Crutches or a walker, with partial weightbearing, are used for two weeks. The usual patient is homebound for approximately ten days. Some patients use home visiting physical therapy three times a week for three weeks. We use coumadin (warfarin) as an anticoagulant. This is to prevent deep vein thrombosis, blood clots, and pulmonary emboli (clots that travel to the lung). The usual total hip arthroplasty patient will use coumadin for 28 days after surgery. Patients that have total knee arthroplasty will use anticoagulant for approximately ten to 28 days depending on their medical condition. The pro-time INR blood test is performed approximately twice weekly as a guide for the correct dosage of coumadin. Outpatient physical therapy is started at four weeks and continues for four to eight weeks. Oral analgesics are used for the first three to four weeks. Common analgesics are propoxyphene, hydrocodone, and oxycodone.
A patient may be able to drive with the right leg at three to four weeks postsurgery. A walking program is begun at three weeks. A person may perform shopping activities at three to four weeks. Pool exercise is encouraged at two to three weeks after surgery. A person may resume golf at six weeks. Lifting and heavy work may begin at eight weeks. Walking for exercise may start at six weeks postsurgery. Bicycling for exercise may begin at four weeks postsurgery. Tennis may begin at eight to 12 weeks postsurgery.
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