The Morning Blend, June 15, 2010

Tucson Citizen           May 17, 2004

COMPUTER-AIDED SURGERY CENTERS KNEE

By Anne T. Denogean

A camera and computer help orthopedic surgeon Dr. David Martin

(left, with nurse Pat Courtier) properly align the new artificial knee

of patient Samuel Collins, 80.

Photo by JEFF STANTON/Tucson Citizen

     Dr. David Martin uses a zirconium oxide artificial knee that is 80 percent harder than steel and should last two decades.

     After Kent Randol, 74, had his left knee replaced nine years ago, he vowed to never again go through such a painful procedure.  But earlier this year when he twisted his degenerating right knee, he faced a second replacement surgery.  The difference this time was that the retired engineer was able to return to the gym and exercise bike 2 1/2 weeks after a "minimally invasive" surgery, compared to hobbling around on crutches for a month after his earlier traditional procedure.  "I think this one is 50 percent easier than the last time, easily," said Randol, who had both surgeries performed by Dr. David Martin.

     With the use of a new surgical cut and a computer system that some call a global positioning system for the human body, orthopedic surgeon Martin is sending knee replacement patients home to a faster, less painful recovery.

     An estimated 250,000 to 300,000 Americans need knee replacement surgery each year, and the numbers can be expected to grow as the baby boomer generation ages.  Most knee replacement surgeries are done on people ages 60 to 80, mostly due to osteoarthritis, according to the UAB Health System website.

     The minimally invasive surgery gaining popularity for more than a year now uses an incision less than half as long as the traditional cut.  "I had a patient come in here yesterday who had full extension and flexion of 125 degrees and asked, 'Can I go golfing?' " Martin said.  "He was only two weeks out (from surgery).  They do dramatically better, no question about it.  "If somebody ! had told me how my patients would react to this, I wouldn't have believed them."  He said he expects the procedure will become the standard within the next two years.

     A surgeon in Chicago even offers the surgery as an outpatient procedure, with patients going home within hours of the operation.  But Martin said that's realistic for only the healthiest of patients.  For example, after Samuel Collins, 80, a retired lawyer and judge, had the new procedure, his knee healed fine, Martin said.  But Collins' overall recovery was somewhat slower because of other medical issues.

     Martin is among the most experienced surgeons in the nation doing minimally invasive knee surgeries with an image-guided surgery computer.  He has performed more than 200 minimally invasive knee replacement surgeries, using the computer program to perfectly align the knee between the hip and ankle.  He believes at least one other Tucson surgeon is doing the minimally invasive procedure and, nationally, about 5 percent of surgeons use the technique.  Other Tucson orthopedic surgeons do various forms of knee replacement surgery and one touts a minimally invasive partial replacement.

Incision Avoids Muscle

     During a knee replacement surgery, the surgeon removes the top portion of the tibia and lower portion of the femur, replacing the bone and cartilage with a metal-and-plastic device that simulates the natural hinge of the human knee.

     The traditional surgical cut for a knee replacement, Martin said, is 8 to 10 inches long - a straight line that goes from 4 to 5 inches above the joint and at least 3 inches below it.  The new incision used by some surgeons in this less invasive procedure is 3 to 5 inches.  It runs about a half-inch below the joint line to about three-quarters of an inch above the kneecap, Martin said.  The new cut also veers to the inside of the knee instead of slicing through the quadriceps.  The cut spares muscles and tendons that are critical to the flexing of the knee, reducing the pain of post-surgical therapy and recovery time, Martin said.

      Doctors have done knee replacements for about 35 years.  They always believed that splitting the vastus medialis muscle, located on the inner thigh and responsible for knee extension, would compromise the function of the knee.  They've learned over time that they can split it, which may happen in the new procedure, without compromising the function of the knee, Martin said.

Knee Perfectly Centered

     The difference between how Martin does the procedure and how most other surgeons do it is that he uses a computer to aid him, he said.  It's critical to center the replacement knee between the centers of the hip and ankle.  The computer "lets you line it up perfectly every time," he said.

      The system uses six reflective balls the size of marbles placed in the femur and tibia.  A camera takes the information from the balls to create an image of the knee's anatomy that helps Martin decide where to make his bone cuts to place the knee correctly.  An improperly aligned knee won't last as long as it should, he said.  The person's weight won't sit right, and the metal component will toggle loose from the bone, or the white polyethylene padding between the femur and tibia will wear out.

      Martin said the most accurate of the traditional ways of lining up the knee uses a rod that goes down the femur and tibia.  But in two-thirds of knee replacement surgeries, people's tibias are bowed, making the rods inaccurate, he said.  "When they use the rods, they can only be about 60 percent accurate with that," Martin said.

      The standard of care without computers is plus or minus 2 degrees off perfect alignment, Martin said. Using the computer has made him accurate to within one degree 95 percent of the time, he said.

Same Risk Of Complications

     Martin said the possible complications from surgery are the same as those in the traditional procedure, the most common being blood clots.  Infections will afflict fewer than 1 percent of patients.  And regardless of how well a surgery is done, there are a small number of people whose bodies will produce so much scar tissue it will restrict their range of motion, he said.

      No studies exist showing that artificial knees implanted with less-invasive techniques are as durable as those implanted traditionally.  Still, Martin said, there's no reason to believe they wouldn't be.  He uses a zirconium oxide artificial knee that is 80 percent harder than steel.  His goal is to have his knee replacements last 20 years or more, compared to 12 to 15 years for a stainless steel knee implanted using traditional methods.

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Record Number: tuc2004051812061217